{"id":36444,"date":"2026-04-03T14:50:12","date_gmt":"2026-04-03T09:20:12","guid":{"rendered":"https:\/\/atsixty.com\/?p=36444"},"modified":"2026-04-03T14:52:41","modified_gmt":"2026-04-03T09:22:41","slug":"pacemaker-mcq","status":"publish","type":"post","link":"https:\/\/atsixty.com\/index.php\/2026\/04\/03\/pacemaker-mcq\/","title":{"rendered":"Pacemaker MCQ"},"content":{"rendered":"\n<!-- ============================================================\n     PACEMAKER PATHOLOGY & CLINICAL MANAGEMENT \u2014 MCQ SET\n     For atsixty.com | NEET-PG \/ Cardiology revision\n     Author : Avin | Built with AvinQuiz shell\n\n     STRUCTURE OVERVIEW\n     \u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\n     1. <div #atsixty-pm-quiz>   \u2014 outer wrapper (scoped CSS namespace)\n     2. <style>                  \u2014 all CSS scoped to #atsixty-pm-quiz\n     3. .quiz-shell              \u2014 card container, no overflow:hidden\n     4. .quiz-sentinel           \u2014 1 px div; triggers IntersectionObserver\n     5. .status-bar              \u2014 fixed top bar (progress + live stats)\n     6. .quiz-main               \u2014 scrollable question area\n     7. <script> IIFE            \u2014 all JS in an immediately-invoked fn\n          \u2514\u2500 BANK[]              \u2014 question objects (edit content here)\n          \u2514\u2500 shuffle()           \u2014 Fisher-Yates shuffle\n          \u2514\u2500 prepareSession()    \u2014 shuffles BANK + options each load\n          \u2514\u2500 buildQuiz()         \u2014 renders cards from session[]\n          \u2514\u2500 answer()            \u2014 handles click, scores, shows exp.\n          \u2514\u2500 updateStats()       \u2014 updates live counters in status bar\n          \u2514\u2500 showScore()         \u2014 renders final score panel\n          \u2514\u2500 retryQuiz()         \u2014 reshuffles and restarts\n\n     COLOUR PALETTE  (CSS custom properties)\n     \u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\n     --terra      : #C0603A   (terracotta \u2014 primary accent)\n     --teal       : #2A7A6F   (teal \u2014 secondary, explanations)\n     --ink        : #1e1e1e   (body text)\n     --muted      : #6b6b6b   (secondary text, stat labels)\n     --correct-bg : #e8f5e9 \/ --correct-border : #43a047\n     --wrong-bg   : #fdecea  \/ --wrong-border  : #e53935\n\n     TYPOGRAPHY\n     \u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\n     Georgia \/ Times New Roman (serif stack \u2014 matches site theme)\n\n     SCORING (NEET-PG pattern)\n     \u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\n     Correct : +4   Wrong : \u22121   Skipped : 0\n     Net score formula rendered as: c \u00d7 4 \u2212 w   (no brackets)\n\n     HOW TO ADD \/ EDIT QUESTIONS\n     \u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\n     Each object in BANK[] has these keys:\n       q             : question stem (string; <em> for italics)\n       correctAnswer : exact string matching one of the opts[]\n       opts[]        : array of exactly 4 option strings\n       exp           : explanation HTML (<strong> \/ <em> allowed)\n       difficulty    : \"easy\" | \"medium\" | \"hard\"\n       concept       : short tag label (shown as blue badge)\n\n     ANSWER BALANCE (pre-shuffle positions in BANK[])\n     \u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\n     Q1  \u2192 opt[0] (A)   Q2  \u2192 opt[1] (B)   Q3  \u2192 opt[2] (C)\n     Q4  \u2192 opt[3] (D)   Q5  \u2192 opt[0] (A)   Q6  \u2192 opt[1] (B)\n     Q7  \u2192 opt[2] (C)   Q8  \u2192 opt[3] (D)   Q9  \u2192 opt[0] (A)\n     Q10 \u2192 opt[1] (B)   Q11 \u2192 opt[2] (C)   Q12 \u2192 opt[3] (D)\n     Q13 \u2192 opt[0] (A)   Q14 \u2192 opt[1] (B)   Q15 \u2192 opt[3] (D)\n     Distribution : A\u00d74, B\u00d74, C\u00d74, D\u00d73  (Fisher-Yates reshuffles on load)\n\n     ID NAMESPACE  \u2014 all element IDs prefixed \"pm-\" (not \"rp-\")\n     to allow safe co-embedding with other quiz sets on the same page.\n     ============================================================ -->\n\n<div id=\"atsixty-pm-quiz\">\n<style>\n\/* \u2500\u2500 Scoped CSS root \u2014 all rules prefixed #atsixty-pm-quiz \u2500\u2500\u2500\u2500\u2500\u2500\u2500 *\/\n#atsixty-pm-quiz {\n  --terra: #C0603A;\n  --terra-light: #d4795a;\n  --terra-pale: #fdf3ef;\n  --teal: #2A7A6F;\n  --teal-light: #3a9688;\n  --teal-pale: #eef6f5;\n  --ink: #1e1e1e;\n  --muted: #6b6b6b;\n  --rule: #e2d8d4;\n  --correct-bg: #e8f5e9;\n  --correct-border: #43a047;\n  --wrong-bg: #fdecea;\n  --wrong-border: #e53935;\n  --white: #fff;\n  --shadow: 0 2px 16px rgba(192,96,58,0.08);\n  font-family: Georgia, 'Times New Roman', serif;\n  color: var(--ink);\n  margin: 1rem 0 2rem;\n}\n#atsixty-pm-quiz * { box-sizing: border-box; margin: 0; padding: 0; }\n\n\/* \u2500\u2500 Outer shell \u2014 NO overflow:hidden so sentinel reaches observer \u2500 *\/\n#atsixty-pm-quiz .quiz-shell {\n  background: #f7f2ee;\n  border: 1px solid #eee3dd;\n  border-radius: 12px;\n}\n\n\/* \u2500\u2500 1 px sentinel div \u2014 IntersectionObserver watches this \u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500 *\/\n#atsixty-pm-quiz .quiz-sentinel { height: 1px; }\n\n\/* \u2500\u2500 Fixed status bar \u2014 slides down when sentinel leaves viewport \u2500\u2500 *\/\n#atsixty-pm-quiz .status-bar {\n  position: fixed;\n  top: 0; left: 0; right: 0;\n  z-index: 99999;\n  background: var(--white);\n  border-bottom: 2px solid var(--rule);\n  border-left: 4px solid var(--terra);\n  box-shadow: 0 2px 12px rgba(0,0,0,0.11);\n  opacity: 0;\n  pointer-events: none;\n  transform: translateY(-110%);\n  transition: opacity 0.22s ease, transform 0.22s ease;\n}\n#atsixty-pm-quiz .status-bar.visible {\n  opacity: 1;\n  pointer-events: auto;\n  transform: translateY(0);\n}\n\n\/* \u2500\u2500 Progress bar inside status bar \u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500 *\/\n#atsixty-pm-quiz .progress-wrap { background: #e0d8d4; height: 5px; }\n#atsixty-pm-quiz .progress-bar {\n  height: 100%;\n  background: linear-gradient(90deg, var(--terra), var(--teal));\n  width: 0%;\n  transition: width 0.4s ease;\n}\n\n\/* \u2500\u2500 Stat items row inside status bar \u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500 *\/\n#atsixty-pm-quiz .stats {\n  display: flex;\n  align-items: center;\n  padding: 0.4rem 0.85rem;\n  font-size: 0.72rem;\n  color: var(--muted);\n  flex-wrap: nowrap;\n  overflow-x: auto;\n}\n#atsixty-pm-quiz .stat-item {\n  display: flex;\n  align-items: center;\n  gap: 0.22rem;\n  padding: 0.1rem 0.55rem;\n  border-right: 1px solid var(--rule);\n  white-space: nowrap;\n  line-height: 1;\n}\n#atsixty-pm-quiz .stat-item:last-child { border-right: none; }\n#atsixty-pm-quiz .dot {\n  width: 7px; height: 7px;\n  border-radius: 50%;\n  display: inline-block;\n  flex-shrink: 0;\n}\n#atsixty-pm-quiz .dot-correct { background: var(--correct-border); }\n#atsixty-pm-quiz .dot-wrong   { background: var(--wrong-border); }\n#atsixty-pm-quiz .dot-rem     { background: #aaa; }\n#atsixty-pm-quiz .dot-net     { background: var(--terra); }\n#atsixty-pm-quiz .stats strong { color: var(--ink); font-size: 0.82rem; font-weight: 700; }\n#atsixty-pm-quiz .sep { flex: 1; min-width: 0.3rem; }\n\n\/* \u2500\u2500 Main quiz body \u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500 *\/\n#atsixty-pm-quiz .quiz-main {\n  padding: 0.75rem 0.65rem 2.5rem;\n  max-width: 700px;\n  margin: 0 auto;\n}\n\n\/* \u2500\u2500 Question cards \u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500 *\/\n#atsixty-pm-quiz .q-card {\n  background: var(--white);\n  border-radius: 8px;\n  box-shadow: var(--shadow);\n  margin-bottom: 0.95rem;\n  overflow: hidden;\n  border: 1px solid var(--rule);\n  transition: box-shadow 0.2s;\n}\n#atsixty-pm-quiz .q-card:hover { box-shadow: 0 4px 24px rgba(192,96,58,0.13); }\n#atsixty-pm-quiz .q-head {\n  display: flex;\n  align-items: flex-start;\n  gap: 0.55rem;\n  padding: 0.72rem 0.75rem 0.6rem;\n  border-bottom: 1px solid var(--rule);\n}\n\n\/* \u2500\u2500 Question number bubble \u2014 turns green\/red after answer \u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500 *\/\n#atsixty-pm-quiz .q-num {\n  flex-shrink: 0;\n  width: 24px; height: 24px;\n  border-radius: 50%;\n  background: var(--terra);\n  color: #fff;\n  font-size: 0.72rem;\n  font-weight: 700;\n  display: flex;\n  align-items: center;\n  justify-content: center;\n}\n#atsixty-pm-quiz .q-num.answered-c { background: var(--correct-border); }\n#atsixty-pm-quiz .q-num.answered-w { background: var(--wrong-border); }\n#atsixty-pm-quiz .q-text { font-size: 0.89rem; line-height: 1.58; color: var(--ink); }\n#atsixty-pm-quiz .q-text em { font-style: italic; color: var(--teal); }\n\n\/* \u2500\u2500 Answer options \u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500 *\/\n#atsixty-pm-quiz .options { padding: 0.35rem 0.6rem 0.6rem; }\n#atsixty-pm-quiz .opt {\n  display: flex;\n  align-items: flex-start;\n  gap: 0.5rem;\n  padding: 0.46rem 0.6rem;\n  margin: 0.28rem 0;\n  border-radius: 6px;\n  border: 1.5px solid var(--rule);\n  cursor: pointer;\n  font-size: 0.84rem;\n  line-height: 1.42;\n  color: var(--ink);\n  background: #fdfdfd;\n  transition: border-color 0.15s, background 0.15s;\n  -webkit-tap-highlight-color: transparent;\n}\n#atsixty-pm-quiz .opt:hover { border-color: var(--terra-light); background: var(--terra-pale); }\n#atsixty-pm-quiz .opt-letter {\n  flex-shrink: 0;\n  width: 20px; height: 20px;\n  border-radius: 50%;\n  border: 1.5px solid var(--rule);\n  display: flex;\n  align-items: center;\n  justify-content: center;\n  font-size: 0.65rem;\n  font-weight: 700;\n  color: var(--muted);\n  transition: all 0.15s;\n  margin-top: 1px;\n}\n\/* Correct option \u2014 green fill *\/\n#atsixty-pm-quiz .opt.correct { background: var(--correct-bg); border-color: var(--correct-border); cursor: default; }\n#atsixty-pm-quiz .opt.correct .opt-letter { background: var(--correct-border); border-color: var(--correct-border); color: #fff; }\n\/* Wrong option \u2014 red fill *\/\n#atsixty-pm-quiz .opt.wrong   { background: var(--wrong-bg);   border-color: var(--wrong-border);   cursor: default; }\n#atsixty-pm-quiz .opt.wrong .opt-letter   { background: var(--wrong-border);   border-color: var(--wrong-border);   color: #fff; }\n\/* Unchosen options after answer \u2014 dimmed *\/\n#atsixty-pm-quiz .opt.dimmed  { opacity: 0.45; cursor: default; }\n\n\/* \u2500\u2500 Explanation panel \u2014 hidden until answered \u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500 *\/\n#atsixty-pm-quiz .explanation {\n  display: none;\n  background: var(--teal-pale);\n  border-top: 1px solid #b2d8d3;\n  padding: 0.65rem 0.75rem;\n  font-size: 0.8rem;\n  line-height: 1.6;\n  color: #1a4f49;\n}\n#atsixty-pm-quiz .explanation.show { display: block; animation: pmFadeIn 0.25s ease; }\n#atsixty-pm-quiz .exp-label {\n  display: flex;\n  align-items: center;\n  gap: 0.45rem;\n  font-size: 0.72rem;\n  font-weight: 700;\n  letter-spacing: 0.08em;\n  text-transform: uppercase;\n  color: var(--teal);\n  margin-bottom: 0.3rem;\n}\n\n\/* \u2500\u2500 Difficulty badge \u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500 *\/\n#atsixty-pm-quiz .diff {\n  font-size: 0.6rem;\n  font-weight: 700;\n  letter-spacing: 0.07em;\n  text-transform: uppercase;\n  padding: 0.1rem 0.4rem;\n  border-radius: 3px;\n  line-height: 1.5;\n}\n#atsixty-pm-quiz .diff-easy   { background: #e8f5e9; color: #2e7d32; }\n#atsixty-pm-quiz .diff-medium { background: #fff8e1; color: #e65100; }\n#atsixty-pm-quiz .diff-hard   { background: #fdecea; color: #c62828; }\n\n\/* \u2500\u2500 Concept tag (blue pill) \u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500 *\/\n#atsixty-pm-quiz .tag-concept {\n  font-size: 0.6rem;\n  font-weight: 700;\n  letter-spacing: 0.07em;\n  text-transform: uppercase;\n  padding: 0.1rem 0.4rem;\n  border-radius: 3px;\n  line-height: 1.5;\n  background: #e8eaf6;\n  color: #3949ab;\n}\n#atsixty-pm-quiz .explanation strong { color: var(--teal); }\n#atsixty-pm-quiz .explanation em { font-style: italic; }\n\n\/* \u2500\u2500 Final score panel \u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500 *\/\n#atsixty-pm-quiz .score-panel {\n  display: none;\n  background: var(--white);\n  border-radius: 10px;\n  border: 2px solid var(--terra);\n  box-shadow: var(--shadow);\n  padding: 1.5rem 1.2rem;\n  margin: 1rem 0 1.2rem;\n  text-align: center;\n}\n#atsixty-pm-quiz .score-panel h2 { font-size: 1.4rem; color: var(--ink); margin-bottom: 0.3rem; }\n#atsixty-pm-quiz .score-num  { font-size: 3rem; font-weight: 700; color: var(--terra); line-height: 1.1; }\n#atsixty-pm-quiz .score-denom { font-size: 1.05rem; color: var(--muted); margin-bottom: 0.4rem; }\n#atsixty-pm-quiz .grade-bar  { height: 8px; border-radius: 4px; background: #eee; overflow: hidden; margin: 0.5rem auto 1rem; max-width: 260px; }\n#atsixty-pm-quiz .grade-fill { height: 100%; border-radius: 4px; background: linear-gradient(90deg, var(--terra), var(--teal)); transition: width 0.8s ease; }\n#atsixty-pm-quiz .score-breakdown { display: flex; justify-content: center; gap: 1rem; margin-bottom: 0.6rem; font-size: 0.78rem; color: var(--muted); text-align: center; flex-wrap: wrap; }\n#atsixty-pm-quiz .score-breakdown span { line-height: 1.5; }\n#atsixty-pm-quiz .score-breakdown span strong { display: block; font-size: 1.1rem; color: var(--ink); }\n#atsixty-pm-quiz .score-breakdown small { font-size: 0.7rem; color: var(--terra); }\n#atsixty-pm-quiz .score-formula { font-size: 0.78rem; color: var(--muted); background: #fdf3ef; border-radius: 6px; padding: 0.45rem 0.8rem; margin: 0.5rem auto 0.8rem; display: inline-block; line-height: 1.6; }\n#atsixty-pm-quiz .score-formula strong { color: var(--terra); }\n#atsixty-pm-quiz .score-msg { font-size: 0.9rem; color: var(--muted); margin-bottom: 1rem; font-style: italic; line-height: 1.6; }\n#atsixty-pm-quiz .btn-retry { background: var(--terra); color: #fff; border: none; padding: 0.6rem 1.6rem; border-radius: 6px; font-size: 0.9rem; cursor: pointer; transition: background 0.2s; }\n#atsixty-pm-quiz .btn-retry:hover { background: var(--terra-light); }\n\n\/* \u2500\u2500 Floating \"View Score\" button \u2014 appears when all answered \u2500\u2500\u2500\u2500\u2500\u2500\u2500 *\/\n#atsixty-pm-quiz .submit-btn {\n  position: fixed;\n  bottom: 1.2rem; left: 50%;\n  transform: translateX(-50%);\n  background: var(--teal);\n  color: #fff;\n  border: none;\n  padding: 0.75rem 2.2rem;\n  border-radius: 50px;\n  font-size: 0.95rem;\n  font-weight: 700;\n  cursor: pointer;\n  box-shadow: 0 4px 20px rgba(42,122,111,0.35);\n  display: none;\n  z-index: 200;\n  transition: background 0.2s;\n}\n#atsixty-pm-quiz .submit-btn:hover { background: var(--teal-light); }\n#atsixty-pm-quiz .submit-btn.visible { display: block; animation: pmSlideUp 0.3s ease; }\n\n\/* \u2500\u2500 Keyframe animations \u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500 *\/\n@keyframes pmFadeIn  { from { opacity:0; transform:translateY(-4px); } to { opacity:1; transform:translateY(0); } }\n@keyframes pmSlideUp { from { opacity:0; transform:translateX(-50%) translateY(12px); } to { opacity:1; transform:translateX(-50%) translateY(0); } }\n<\/style>\n\n<!-- \u2500\u2500 HTML STRUCTURE \u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500 -->\n<div class=\"quiz-shell\">\n\n  <!-- Sentinel: 1px div at the top; when it scrolls out, status bar appears -->\n  <div class=\"quiz-sentinel\" id=\"pm-sentinel\"><\/div>\n\n  <!-- Fixed status bar: progress strip + live score counters -->\n  <div class=\"status-bar\" id=\"pm-status-bar\">\n    <div class=\"progress-wrap\"><div class=\"progress-bar\" id=\"pm-progress\"><\/div><\/div>\n    <div class=\"stats\">\n      <div class=\"stat-item\"><span class=\"dot dot-correct\"><\/span> \u2713 <strong id=\"pm-sc\">0<\/strong><\/div>\n      <div class=\"stat-item\"><span class=\"dot dot-wrong\"><\/span> \u2717 <strong id=\"pm-sw\">0<\/strong><\/div>\n      <div class=\"stat-item\"><span class=\"dot dot-rem\"><\/span> Left <strong id=\"pm-sr\">15<\/strong><\/div>\n      <div class=\"sep\"><\/div>\n      <div class=\"stat-item\"><span class=\"dot dot-net\"><\/span> Net <strong id=\"pm-sn\">0<\/strong><\/div>\n      <div class=\"stat-item\">Max <strong id=\"pm-sm\">60<\/strong><\/div>\n    <\/div>\n  <\/div>\n\n  <!-- Quiz main area: cards injected here by buildQuiz() -->\n  <div class=\"quiz-main\">\n    <div id=\"pm-container\"><\/div>\n    <!-- Floating submit button \u2014 hidden until all questions answered -->\n    <button class=\"submit-btn\" id=\"pm-submit\">View Score \u2192<\/button>\n    <!-- Score panel \u2014 hidden until submit clicked -->\n    <div class=\"score-panel\" id=\"pm-score\"><\/div>\n  <\/div>\n\n<\/div><!-- \/.quiz-shell -->\n\n<!-- \u2500\u2500 JAVASCRIPT \u2014 all logic in a self-contained IIFE \u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500 -->\n<script>\n(function () {\n\n  \/* \u2500\u2500 DOM reference object \u2014 collected once at startup \u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500 *\/\n  const Q = {\n    container : document.getElementById('pm-container'),\n    submit    : document.getElementById('pm-submit'),\n    score     : document.getElementById('pm-score'),\n    progress  : document.getElementById('pm-progress'),\n    sc: document.getElementById('pm-sc'),   \/\/ correct count\n    sw: document.getElementById('pm-sw'),   \/\/ wrong count\n    sr: document.getElementById('pm-sr'),   \/\/ remaining count\n    sn: document.getElementById('pm-sn'),   \/\/ net score\n    sm: document.getElementById('pm-sm')    \/\/ max score\n  };\n\n  \/* \u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\n     QUESTION BANK\n     \u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\n     Edit questions here. Each object:\n       q             \u2014 stem text (HTML allowed; use <em> for italics)\n       correctAnswer \u2014 must match one opts[] string exactly\n       opts[]        \u2014 exactly 4 options\n       exp           \u2014 explanation (HTML; <strong> \/ <em> ok)\n       difficulty    \u2014 \"easy\" | \"medium\" | \"hard\"\n       concept       \u2014 short label for the blue concept tag\n     \u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550 *\/\n  const BANK = [\n\n    \/* Q1 \u2014 correct: opts[0] = A ---------------------------------- *\/\n    {\n      q: \"A 68-year-old man has a resting heart rate of 36 bpm, fatigue, and exertional dyspnoea. ECG shows P waves at 70\/min with no fixed relationship to QRS complexes; QRS complexes occur at 36\/min and are wide (120 ms). Blood pressure is 90\/60 mmHg. The most appropriate immediate management is:\",\n      correctAnswer: \"Temporary transvenous pacing followed by permanent pacemaker implantation\",\n      opts: [\n        \"Temporary transvenous pacing followed by permanent pacemaker implantation\",\n        \"IV atropine 0.5 mg and observe for 24 hours before deciding on pacing\",\n        \"Transcutaneous (external) pacing as definitive long-term therapy\",\n        \"Oral theophylline for rate enhancement; no pacing required if asymptomatic\"\n      ],\n      exp: \"<strong>Complete (third-degree) AV block<\/strong>: total dissociation of atrial and ventricular activity. Ventricular escape rhythm \u2014 wide QRS (below His bundle), rate 20\u201340 bpm. Haemodynamically compromised (hypotension, presyncope\/syncope \u2014 <em>Stokes-Adams attacks<\/em>). Management: <strong>temporary transvenous pacing<\/strong> as a bridge \u2192 <strong>permanent pacemaker<\/strong> (Class I indication). Atropine has limited effect on infranodal block and is not definitive. Transcutaneous pacing: emergency bridge only, painful, unreliable long-term. Theophylline: no role in complete heart block.\",\n      difficulty: \"easy\",\n      concept: \"Complete AV Block\"\n    },\n\n    \/* Q2 \u2014 correct: opts[1] = B ---------------------------------- *\/\n    {\n      q: \"A 72-year-old woman with a newly implanted dual-chamber pacemaker (DDD mode) undergoes a pre-discharge chest X-ray. The attending physician notices the ventricular lead tip is projecting over the right ventricular apex and the atrial lead tip is in the right atrial appendage. Twenty-four hours later, the patient develops pleuritic chest pain, hypotension, and raised JVP. ECG shows loss of capture with each pacing spike. The most likely complication is:\",\n      correctAnswer: \"Cardiac tamponade from ventricular lead perforation\",\n      opts: [\n        \"Pneumothorax from subclavian vein puncture during lead insertion\",\n        \"Cardiac tamponade from ventricular lead perforation\",\n        \"Lead displacement into the right ventricular outflow tract causing non-capture\",\n        \"Pacemaker-mediated tachycardia from retrograde VA conduction\"\n      ],\n      exp: \"<strong>Cardiac tamponade<\/strong>: early complication of pacemaker implantation (incidence ~0.1\u20130.8%). Ventricular lead tip perforates thin RV apex (especially in elderly women with thin walls) \u2192 haemopericardium \u2192 tamponade. Beck's triad: <strong>hypotension + raised JVP + muffled heart sounds<\/strong>. ECG: loss of capture (lead no longer in myocardium). CXR may show widened mediastinum. Confirm with echocardiography. Treatment: <strong>urgent pericardiocentesis<\/strong> \u00b1 surgical repair. Pneumothorax: occurs at time of venous access, presents earlier. Lead displacement: loss of capture without haemodynamic compromise.\",\n      difficulty: \"medium\",\n      concept: \"Pacemaker Perforation\"\n    },\n\n    \/* Q3 \u2014 correct: opts[2] = C ---------------------------------- *\/\n    {\n      q: \"A pacemaker is programmed in VVI mode. The patient's underlying rhythm is sinus tachycardia at 110 bpm. The pacemaker lower rate limit is set at 60 bpm. Which of the following best describes the pacemaker's behaviour?\",\n      correctAnswer: \"The pacemaker senses the intrinsic ventricular activity and is inhibited \u2014 no pacing spikes are delivered\",\n      opts: [\n        \"The pacemaker paces the ventricle at 60 bpm, overriding the sinus tachycardia\",\n        \"The pacemaker paces both atrium and ventricle at 110 bpm to track the sinus rate\",\n        \"The pacemaker senses the intrinsic ventricular activity and is inhibited \u2014 no pacing spikes are delivered\",\n        \"The pacemaker switches to asynchronous VOO mode when the intrinsic rate exceeds the programmed rate\"\n      ],\n      exp: \"<strong>VVI pacemaker (NBD\/NASPE code)<\/strong>: V = paces Ventricle, V = senses Ventricle, I = Inhibited by sensed activity. When intrinsic ventricular rate > programmed lower rate limit \u2192 pacemaker is <strong>inhibited<\/strong> \u2014 no spikes delivered. It only paces when the native rate drops below the set rate. Key limitation: <em>no AV synchrony<\/em> (no atrial sensing\/pacing) \u2014 may cause 'pacemaker syndrome' (retrograde VA conduction \u2192 cannon A waves, hypotension). DDD paces and senses both chambers. VVI is appropriate for persistent AF with slow ventricular rate.\",\n      difficulty: \"easy\",\n      concept: \"VVI Mode \u2014 Inhibition\"\n    },\n\n    \/* Q4 \u2014 correct: opts[3] = D ---------------------------------- *\/\n    {\n      q: \"A patient with a DDD pacemaker develops palpitations and a regular tachycardia at exactly the programmed upper rate limit (110 bpm). ECG shows a pacing spike before each QRS with a P wave in the ST segment of the preceding beat. The arrhythmia is initiated after a ventricular ectopic. The most likely diagnosis and mechanism are:\",\n      correctAnswer: \"Pacemaker-mediated tachycardia (PMT) \u2014 retrograde VA conduction sensed by atrial lead triggers ventricular pacing in a re-entry loop\",\n      opts: [\n        \"Runaway pacemaker \u2014 battery depletion causing uncontrolled rapid pacing at >200 bpm\",\n        \"Atrial flutter with 2:1 block tracked by the DDD pacemaker up to the upper rate limit\",\n        \"Pacemaker oversensing \u2014 T-wave sensing by ventricular lead triggers atrial pacing artefact\",\n        \"Pacemaker-mediated tachycardia (PMT) \u2014 retrograde VA conduction sensed by atrial lead triggers ventricular pacing in a re-entry loop\"\n      ],\n      exp: \"<strong>Pacemaker-mediated tachycardia (PMT)<\/strong>: a re-entrant loop using the DDD pacemaker as the antegrade limb. Trigger: usually a <strong>ventricular ectopic<\/strong> \u2014 conducted retrogradely through the AV node \u2192 atrial depolarisation (P wave in ST segment) \u2192 sensed by atrial lead \u2192 pacemaker triggers ventricular pacing \u2192 retrograde conduction again \u2192 perpetuates tachycardia. Rate = upper rate limit. Treatment: <strong>magnet application<\/strong> (converts to asynchronous DOO, breaks loop); reprogram PVARP (post-ventricular atrial refractory period) to longer value. Runaway pacemaker: >200 bpm, end-of-life battery.\",\n      difficulty: \"hard\",\n      concept: \"PMT \u2014 Re-entry\"\n    },\n\n    \/* Q5 \u2014 correct: opts[0] = A ---------------------------------- *\/\n    {\n      q: \"A 65-year-old man presents 4 weeks after pacemaker implantation with fever (38.8\u00b0C), rigors, and a warm, fluctuant swelling over the pacemaker pocket. Blood cultures grow <em>Staphylococcus aureus<\/em>. Transoesophageal echocardiography shows a vegetation on the tricuspid valve leaflet. The most appropriate management is:\",\n      correctAnswer: \"Complete system extraction (generator + all leads) plus prolonged IV antibiotics\",\n      opts: [\n        \"Complete system extraction (generator + all leads) plus prolonged IV antibiotics\",\n        \"Prolonged IV antibiotics alone for 6 weeks with device retention\",\n        \"Pocket debridement and generator replacement with lead preservation\",\n        \"Oral antibiotics for 4 weeks with close outpatient follow-up\"\n      ],\n      exp: \"<strong>CIED (Cardiac Implantable Electronic Device) infection with lead endocarditis<\/strong>: the most serious infectious complication. Bacteraemia + lead vegetation = Class I indication for <strong>complete device and lead extraction<\/strong>. Antibiotics alone cannot sterilise an infected lead (biofilm). Pocket-only infection without lead involvement may occasionally be managed with pocket debridement and generator replacement \u2014 but with lead vegetation\/bacteraemia, full extraction is mandatory. Lead extraction is performed percutaneously using laser or mechanical sheaths or open surgery. IV antibiotics (anti-staphylococcal) for \u22654\u20136 weeks. Re-implantation on the contralateral side after bacteraemia clears.\",\n      difficulty: \"medium\",\n      concept: \"CIED Infection\"\n    },\n\n    \/* Q6 \u2014 correct: opts[1] = B ---------------------------------- *\/\n    {\n      q: \"A 60-year-old woman with a VVI pacemaker for sick sinus syndrome undergoes a routine ECG. The trace shows pacing spikes followed by wide QRS complexes (LBBB morphology) at 70 bpm, interspersed with intrinsic narrow QRS complexes at 65 bpm. Each spike is followed by a QRS without fail. Which pacemaker malfunction pattern does this represent?\",\n      correctAnswer: \"Normal pacemaker function \u2014 appropriate demand pacing with intact capture and sensing\",\n      opts: [\n        \"Failure to capture \u2014 pacing spikes present but no QRS follows consistently\",\n        \"Normal pacemaker function \u2014 appropriate demand pacing with intact capture and sensing\",\n        \"Failure to sense \u2014 pacemaker fires despite adequate intrinsic rhythm (competitive pacing)\",\n        \"Oversensing \u2014 inappropriate inhibition of pacing output by non-cardiac signals\"\n      ],\n      exp: \"<strong>Normal VVI pacemaker behaviour<\/strong>: (1) <strong>Capture<\/strong> \u2014 every spike is followed by a QRS \u2713. (2) <strong>Sensing<\/strong> \u2014 intrinsic beats at 65 bpm (above lower rate limit 70 \u2014 wait, here intrinsic is 65 < 70, so pacemaker fires) \u2192 actually consistent with demand pacing kicking in. Paced QRS: LBBB morphology (expected \u2014 RV apex pacing). Key patterns: <em>failure to capture<\/em> = spike without QRS; <em>failure to sense<\/em> = spike fires into T wave or after native QRS (competing); <em>oversensing<\/em> = inhibition of output despite native rate falling below set rate. This ECG shows none of those \u2014 function is intact.\",\n      difficulty: \"medium\",\n      concept: \"Pacemaker ECG \u2014 Normal\"\n    },\n\n    \/* Q7 \u2014 correct: opts[2] = C ---------------------------------- *\/\n    {\n      q: \"A 70-year-old man with a permanent pacemaker requires an elective inguinal hernia repair under general anaesthesia. The surgical team plans to use monopolar diathermy. Which of the following is the most important precaution regarding pacemaker management intraoperatively?\",\n      correctAnswer: \"Place the diathermy return pad as far from the pacemaker as possible and use short bursts; have a magnet available to convert to asynchronous mode if inhibition occurs\",\n      opts: [\n        \"Pacemaker must be explanted before any surgical procedure involving diathermy\",\n        \"Use only bipolar diathermy below the umbilicus \u2014 monopolar is absolutely contraindicated\",\n        \"Place the diathermy return pad as far from the pacemaker as possible and use short bursts; have a magnet available to convert to asynchronous mode if inhibition occurs\",\n        \"Programme the pacemaker to VOO (asynchronous) mode preoperatively in all cases regardless of pacemaker dependency\"\n      ],\n      exp: \"<strong>Pacemaker + diathermy<\/strong>: EMI (electromagnetic interference) from monopolar diathermy can be sensed as cardiac activity \u2192 pacemaker <strong>inhibition<\/strong> (dangerous if pacemaker-dependent). Key precautions: (1) place return pad <strong>away from the device<\/strong> (current path should not cross generator); (2) use <strong>bipolar diathermy<\/strong> where possible; (3) use <strong>short, intermittent bursts<\/strong>; (4) have a <strong>magnet available<\/strong> \u2014 application converts DDD\/VVI to asynchronous (DOO\/VOO), guaranteeing pacing. Reprogramming to asynchronous is indicated only in pacemaker-<em>dependent<\/em> patients; not universally required. Explantation is never necessary.\",\n      difficulty: \"medium\",\n      concept: \"Pacemaker + Diathermy\"\n    },\n\n    \/* Q8 \u2014 correct: opts[3] = D ---------------------------------- *\/\n    {\n      q: \"A 55-year-old woman with dilated cardiomyopathy, NYHA Class III symptoms, LVEF 28%, sinus rhythm, and a QRS duration of 158 ms (LBBB morphology) is on optimised medical therapy (ACE inhibitor, beta-blocker, aldosterone antagonist). Which device therapy is most appropriate?\",\n      correctAnswer: \"Cardiac resynchronisation therapy (CRT-P or CRT-D) \u2014 biventricular pacing to correct mechanical dyssynchrony\",\n      opts: [\n        \"Conventional dual-chamber pacemaker (DDD) for rate support only\",\n        \"Implantable cardioverter-defibrillator (ICD) alone \u2014 no pacing indication\",\n        \"VVI pacemaker \u2014 rate support with minimal haemodynamic impact\",\n        \"Cardiac resynchronisation therapy (CRT-P or CRT-D) \u2014 biventricular pacing to correct mechanical dyssynchrony\"\n      ],\n      exp: \"<strong>Cardiac resynchronisation therapy (CRT)<\/strong>: indicated when all three criteria are met: (1) symptomatic HF (NYHA II\u2013IV) on OMT, (2) LVEF \u226435%, (3) QRS \u2265130 ms with LBBB morphology (strongest evidence \u2265150 ms). Biventricular pacing (RV + LV via coronary sinus lead) corrects interventricular and intraventricular dyssynchrony \u2192 improves LVEF, reduces hospitalisation, reduces mortality. <strong>CRT-D<\/strong> (with ICD) preferred if LVEF \u226435% and life expectancy >1 year (SCD prevention). CRT-P: when ICD not indicated. LBBB + QRS 158 ms is the ideal substrate. Conventional pacemaker does not resynchronise.\",\n      difficulty: \"medium\",\n      concept: \"CRT \u2014 Biventricular Pacing\"\n    },\n\n    \/* Q9 \u2014 correct: opts[0] = A ---------------------------------- *\/\n    {\n      q: \"A 78-year-old man presents with recurrent syncope on exertion. ECG shows alternating RBBB and LBBB (bifascicular block with intermittent complete heart block). 24-hour Holter confirms 8-second asystolic pause during an episode. His baseline PR interval is 240 ms. The most appropriate action is:\",\n      correctAnswer: \"Permanent pacemaker implantation \u2014 symptomatic high-degree AV block with documented pause is a Class I indication\",\n      opts: [\n        \"Permanent pacemaker implantation \u2014 symptomatic high-degree AV block with documented pause is a Class I indication\",\n        \"Electrophysiology study (EPS) to measure HV interval before deciding on pacing\",\n        \"Implantable loop recorder for further rhythm documentation before any intervention\",\n        \"Oral isoproterenol infusion as long-term therapy for chronotropic incompetence\"\n      ],\n      exp: \"<strong>Symptomatic complete (or high-degree) AV block with documented pause<\/strong>: Class I ACC\/AHA indication for permanent pacemaker. An 8-second pause during syncope is definitively diagnostic \u2014 EPS or loop recorder are unnecessary when the event-ECG correlation is already established. Alternating BBB indicates diffuse His-Purkinje disease (trifascicular block) \u2192 high risk of progression to complete heart block. EPS (HV >100 ms) is useful when block is <em>suspected but not documented<\/em>. Isoproterenol: emergency bridge only, no long-term role. Mode choice: typically DDD (dual-chamber), preserving AV synchrony.\",\n      difficulty: \"easy\",\n      concept: \"Pacing Indications \u2014 Class I\"\n    },\n\n    \/* Q10 \u2014 correct: opts[1] = B --------------------------------- *\/\n    {\n      q: \"Three months after pacemaker implantation via the left subclavian vein, a 63-year-old man develops progressive swelling of the left arm, dilated superficial veins over the chest, and discomfort. Doppler ultrasound of the left subclavian and axillary veins is non-diagnostic due to poor acoustic window. The most appropriate next investigation is:\",\n      correctAnswer: \"CT venography (or contrast venography) of the subclavian and superior vena cava\",\n      opts: [\n        \"Chest X-ray to check lead position and identify any fracture\",\n        \"CT venography (or contrast venography) of the subclavian and superior vena cava\",\n        \"Transthoracic echocardiography to assess right atrial pressure and tricuspid regurgitation\",\n        \"V\/Q scan to exclude pulmonary embolism as the cause of arm swelling\"\n      ],\n      exp: \"<strong>Pacemaker lead\u2013related venous thrombosis \/ subclavian vein occlusion<\/strong>: occurs in 15\u201330% of patients (often asymptomatic). Symptomatic cases: arm oedema, collateral chest veins, pain \u2014 suggesting subclavian or SVC occlusion. Doppler: limited by lead artefact and body habitus. Gold standard: <strong>contrast venography<\/strong> (or CT venography) \u2014 delineates extent of occlusion from subclavian to SVC. Management: anticoagulation; balloon venoplasty \u00b1 stenting if symptomatic. SVC syndrome (bilateral): rare, may require stenting. CXR: assesses lead integrity but not venous patency. TTE: screens for thrombus on lead, not venous occlusion.\",\n      difficulty: \"medium\",\n      concept: \"Lead Venous Thrombosis\"\n    },\n\n    \/* Q11 \u2014 correct: opts[2] = C --------------------------------- *\/\n    {\n      q: \"A pacemaker ECG shows pacing spikes occurring at regular intervals with no relationship to any QRS complex \u2014 spikes fall within QRS complexes, on T waves, and on spontaneous P waves without any consistent capture. The pacemaker's lower rate limit is 70 bpm; the intrinsic heart rate is 80 bpm. Which malfunction does this represent and what is the principal danger?\",\n      correctAnswer: \"Failure to sense (undersensing) \u2014 competitive pacing during vulnerable period risks R-on-T phenomenon and ventricular fibrillation\",\n      opts: [\n        \"Failure to capture \u2014 pacing spikes with no subsequent depolarisation due to lead displacement\",\n        \"Oversensing \u2014 inappropriate inhibition due to sensing non-cardiac signals such as myopotentials\",\n        \"Failure to sense (undersensing) \u2014 competitive pacing during vulnerable period risks R-on-T phenomenon and ventricular fibrillation\",\n        \"End-of-life battery \u2014 irregular spike rate with gradual rate slowing indicates ERI (elective replacement indicator)\"\n      ],\n      exp: \"<strong>Failure to sense (undersensing)<\/strong>: pacemaker does not detect intrinsic cardiac activity \u2192 fires regardless of native beats \u2192 <strong>competitive pacing<\/strong>. Critical danger: a spike landing on the T wave (<em>R-on-T phenomenon<\/em>) during the ventricular vulnerable period \u2192 <strong>ventricular fibrillation<\/strong>. Causes: lead displacement, lead maturation (increased sensing threshold), programming error (sensitivity too low), lead fracture, generator failure. Correction: increase pacemaker sensitivity (lower mV threshold), reposition lead. Compare: <em>oversensing<\/em> = pacemaker sees non-cardiac signals \u2192 inhibition \u2192 pauses.\",\n      difficulty: \"hard\",\n      concept: \"Undersensing \u2014 R-on-T\"\n    },\n\n    \/* Q12 \u2014 correct: opts[3] = D --------------------------------- *\/\n    {\n      q: \"A 66-year-old woman with a DDDR pacemaker reports increasing breathlessness and a sensation of pulsations in her neck at rest. BP drops from 130\/80 to 95\/60 mmHg when pacing is active. Echocardiography shows vigorous atrial contraction against a closed mitral valve. The mechanism of her symptoms is best explained by:\",\n      correctAnswer: \"Pacemaker syndrome \u2014 loss of AV synchrony (ventricular pacing without preceding atrial contraction) causing haemodynamic compromise\",\n      opts: [\n        \"Battery depletion causing rate drop to ERI rate with inadequate cardiac output\",\n        \"CRT-induced dyssynchrony from inadvertent biventricular pacing mode switch\",\n        \"Phrenic nerve stimulation from LV lead causing diaphragmatic pacing and dyspnoea\",\n        \"Pacemaker syndrome \u2014 loss of AV synchrony (ventricular pacing without preceding atrial contraction) causing haemodynamic compromise\"\n      ],\n      exp: \"<strong>Pacemaker syndrome<\/strong>: haemodynamic and symptomatic consequence of <strong>AV dyssynchrony<\/strong>. Most classic with VVI pacing (ventricle paced, no atrial tracking) \u2014 atrium contracts against closed AV valve \u2192 cannon A waves in JVP, neck pulsations, hypotension, dyspnoea, fatigue. Can also occur with DDD if AV interval is too short or too long (atrium fires at wrong phase). Mechanism: loss of the 'atrial kick' contribution to CO (15\u201330%) + retrograde VA conduction elevating atrial pressure. Treatment: reprogram AV delay (optimise) or upgrade to AV-synchronous pacing. Phrenic nerve stimulation: hiccups\/diaphragm twitch, not haemodynamic collapse.\",\n      difficulty: \"hard\",\n      concept: \"Pacemaker Syndrome\"\n    },\n\n    \/* Q13 \u2014 correct: opts[0] = A --------------------------------- *\/\n    {\n      q: \"A 74-year-old man with a permanent pacemaker is admitted for an MRI of the lumbar spine. The cardiologist reviews the device: it is labelled 'MRI-conditional' (1.5 T). Which statement correctly describes the main risk that MRI poses to a conventional (non-conditional) pacemaker and the specific physical mechanism?\",\n      correctAnswer: \"Radiofrequency pulses can induce current in the pacemaker lead, causing tip heating, cardiac stimulation, or inhibition of pacing output\",\n      opts: [\n        \"Radiofrequency pulses can induce current in the pacemaker lead, causing tip heating, cardiac stimulation, or inhibition of pacing output\",\n        \"The static magnetic field permanently demagnetises the generator battery, causing immediate power failure\",\n        \"Gradient magnetic fields cause mechanical displacement of the generator but do not affect lead function\",\n        \"MRI contrast agents (gadolinium) are nephrotoxic and indirectly worsen pacemaker battery longevity\"\n      ],\n      exp: \"<strong>MRI and pacemakers \u2014 risks<\/strong>: three mechanisms from three MRI components: (1) <strong>Static field (B0)<\/strong>: activates reed switch \u2192 asynchronous mode; torque\/force on ferromagnetic components. (2) <strong>Radiofrequency (RF) pulses<\/strong>: induce current in lead \u2192 <strong>lead tip heating<\/strong> (thermal injury to myocardium), inappropriate sensing\/inhibition, or unintended pacing. (3) <strong>Gradient fields<\/strong>: can cause vibration of device components. RF-induced lead tip heating is the most clinically dangerous mechanism. <strong>MRI-conditional<\/strong> devices: leads have modified design (fewer loops, filters) reducing induced current. Conventional pacemakers: MRI conditionally possible under strict protocols in experienced centres.\",\n      difficulty: \"hard\",\n      concept: \"MRI and Pacemakers\"\n    },\n\n    \/* Q14 \u2014 correct: opts[1] = B --------------------------------- *\/\n    {\n      q: \"A 58-year-old man, 6 weeks post-pacemaker implant, notes intermittent hiccupping synchronous with his pacing rate and twitching of his left chest wall. His pacemaker is a dual-chamber device (DDD) with ventricular lead at the RV apex. Chest X-ray shows the ventricular lead tip projecting beyond the cardiac silhouette into the left hemithorax. The most likely cause is:\",\n      correctAnswer: \"Ventricular lead perforation with phrenic nerve or diaphragmatic pacing\",\n      opts: [\n        \"Pacemaker pocket haematoma compressing the phrenic nerve causing referred hiccups\",\n        \"Ventricular lead perforation with phrenic nerve or diaphragmatic pacing\",\n        \"Twiddler's syndrome \u2014 patient manipulation of generator causing lead retraction and extracardiac pacing\",\n        \"High pacing output (voltage) stimulating intercostal muscles at normal lead position\"\n      ],\n      exp: \"<strong>Ventricular lead perforation<\/strong>: lead tip perforates the RV free wall and stimulates adjacent structures. Left hemithorax projection on CXR = lead through RV into pericardial space or beyond. <strong>Phrenic nerve pacing<\/strong>: hiccups synchronous with pacing rate (pathognomonic). <strong>Diaphragmatic pacing<\/strong>: epigastric twitching at pacing rate. Confirmed by CXR + echocardiography (effusion). Management: lead repositioning (percutaneous if acute) or surgical. <em>Twiddler's syndrome<\/em>: patient rotates generator \u2192 lead winds around itself \u2192 retraction\/dislodgement \u2014 CXR shows coiled lead, not extracardiac position. High output alone does not cause perforation.\",\n      difficulty: \"medium\",\n      concept: \"Lead Perforation \u2014 Phrenic\"\n    },\n\n    \/* Q15 \u2014 correct: opts[3] = D --------------------------------- *\/\n    {\n      q: \"A 44-year-old woman presents with recurrent syncope, a structurally normal heart, and QTc of 520 ms on ECG. She has had a cardiac arrest resuscitated with DC cardioversion showing torsades de pointes. Family history is positive for sudden cardiac death in a young sibling. Genetic testing reveals a <em>KCNQ1<\/em> loss-of-function mutation. Besides drug avoidance (QT-prolonging drugs), which device-based therapy has the strongest evidence in her case?\",\n      correctAnswer: \"Implantable cardioverter-defibrillator (ICD) \u2014 secondary prevention after cardiac arrest in long QT syndrome type 1\",\n      opts: [\n        \"Permanent pacemaker at 80 bpm to shorten the QT interval by increasing heart rate\",\n        \"Biventricular pacemaker (CRT) to resynchronise ventricular repolarisation and reduce QT dispersion\",\n        \"Left cardiac sympathetic denervation (LCSD) alone \u2014 stellate ganglionectomy as first-line device-equivalent therapy\",\n        \"Implantable cardioverter-defibrillator (ICD) \u2014 secondary prevention after cardiac arrest in long QT syndrome type 1\"\n      ],\n      exp: \"<strong>Long QT syndrome type 1 (LQT1)<\/strong>: <em>KCNQ1<\/em> mutation \u2192 loss of IKs (slow delayed rectifier K\u207a current) \u2192 prolonged repolarisation \u2192 torsades de pointes \u2192 syncope\/SCA. Triggers: exercise, swimming. <strong>ICD<\/strong>: Class I indication for <strong>secondary prevention<\/strong> (survived cardiac arrest or sustained VT). Also indicated as primary prevention if high-risk (QTc >500 ms, symptoms despite beta-blockers). <em>Beta-blockers<\/em>: first-line pharmacotherapy (especially in LQT1 and LQT2). <em>Pacemaker<\/em>: prevents pause-dependent TdP (more relevant in LQT2\/3, pause-triggered). <em>LCSD<\/em>: adjunctive therapy when ICD shocks persist despite beta-blockers, or when ICD is declined. ICD alone is the definitive secondary prevention device here.\",\n      difficulty: \"hard\",\n      concept: \"ICD \u2014 LQT1 Secondary Prevention\"\n    }\n\n  ]; \/* \u2500\u2500 end BANK[] \u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500 *\/\n\n\n  \/* \u2500\u2500 Fisher-Yates shuffle \u2014 returns a new shuffled array \u2500\u2500\u2500\u2500\u2500\u2500\u2500 *\/\n  function shuffle(arr) {\n    const a = [...arr];\n    for (let i = a.length - 1; i > 0; i--) {\n      const j = Math.floor(Math.random() * (i + 1));\n      [a[i], a[j]] = [a[j], a[i]];\n    }\n    return a;\n  }\n\n  \/* \u2500\u2500 Session state \u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500 *\/\n  let session = [],   \/\/ shuffled question objects (options also shuffled)\n      answered = [],  \/\/ null | 'correct' | 'wrong'\n      total    = 0;   \/\/ count of answered questions\n\n  \/* \u2500\u2500 prepareSession \u2014 shuffles bank and options, resets state \u2500\u2500 *\/\n  function prepareSession() {\n    session = shuffle(BANK).map(q => {\n      const opts = shuffle(q.opts);\n      return { ...q, opts, ansIdx: opts.indexOf(q.correctAnswer) };\n    });\n    answered = new Array(session.length).fill(null);\n    total = 0;\n    Q.sn.textContent = '0';\n    Q.sm.textContent = session.length * 4;\n  }\n\n  \/* \u2500\u2500 Badge helpers \u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500 *\/\n  function diffBadge(d) {\n    return d ? `<span class=\"diff diff-${d}\">${d}<\/span>` : '';\n  }\n  function conceptBadge(c) {\n    return c ? `<span class=\"tag-concept\">${c}<\/span>` : '';\n  }\n\n  \/* \u2500\u2500 buildQuiz \u2014 renders all question cards into #pm-container \u2500 *\/\n  function buildQuiz() {\n    Q.container.innerHTML = '';\n    Q.sr.textContent = session.length;\n\n    session.forEach((q, i) => {\n      const card = document.createElement('div');\n      card.className = 'q-card';\n\n      const letters = ['A','B','C','D'];\n      const optsHTML = q.opts.map((opt, j) => `\n        <div class=\"opt\" id=\"pm-o-${i}-${j}\">\n          <span class=\"opt-letter\">${letters[j]}<\/span>\n          <span>${opt}<\/span>\n        <\/div>`).join('');\n\n      card.innerHTML = `\n        <div class=\"q-head\">\n          <div class=\"q-num\" id=\"pm-n-${i}\">${i + 1}<\/div>\n          <div class=\"q-text\">${q.q}<\/div>\n        <\/div>\n        <div class=\"options\">${optsHTML}<\/div>\n        <div class=\"explanation\" id=\"pm-e-${i}\">\n          <div class=\"exp-label\">Explanation ${diffBadge(q.difficulty)}${conceptBadge(q.concept)}<\/div>\n          ${q.exp}\n        <\/div>`;\n\n      Q.container.appendChild(card);\n\n      \/* Attach click listener to each option *\/\n      q.opts.forEach((_, j) => {\n        document.getElementById(`pm-o-${i}-${j}`)\n          .addEventListener('click', () => answer(i, j));\n      });\n    });\n\n    Q.submit.classList.remove('visible');\n  }\n\n  \/* \u2500\u2500 answer \u2014 called on option click; scores and reveals exp \u2500\u2500 *\/\n  function answer(qi, oi) {\n    if (answered[qi] !== null) return; \/\/ already answered \u2014 ignore\n    const q  = session[qi];\n    const ok = oi === q.ansIdx;\n    answered[qi] = ok ? 'correct' : 'wrong';\n    total++;\n\n    \/* Style options: correct=green, chosen wrong=red, rest=dimmed *\/\n    q.opts.forEach((_, j) => {\n      const el = document.getElementById(`pm-o-${qi}-${j}`);\n      if (j === q.ansIdx)       el.classList.add('correct');\n      else if (j === oi && !ok) el.classList.add('wrong');\n      else                      el.classList.add('dimmed');\n    });\n\n    \/* Show explanation and update question number bubble colour *\/\n    document.getElementById(`pm-e-${qi}`).classList.add('show');\n    document.getElementById(`pm-n-${qi}`).classList.add(ok ? 'answered-c' : 'answered-w');\n\n    updateStats();\n    updateProgress();\n\n    \/* Show floating submit button when all questions are answered *\/\n    if (total === session.length) Q.submit.classList.add('visible');\n  }\n\n  \/* \u2500\u2500 updateStats \u2014 refreshes all counters in the status bar \u2500\u2500\u2500 *\/\n  function updateStats() {\n    const c = answered.filter(a => a === 'correct').length;\n    const w = answered.filter(a => a === 'wrong').length;\n    const r = answered.filter(a => a === null).length;\n    const n = c * 4 - w;   \/\/ NEET-PG scoring: +4 correct, \u22121 wrong\n    Q.sc.textContent = c;\n    Q.sw.textContent = w;\n    Q.sr.textContent = r;\n    Q.sn.textContent = n >= 0 ? '+' + n : n;\n    Q.sm.textContent = session.length * 4;\n  }\n\n  \/* \u2500\u2500 updateProgress \u2014 fills the progress bar proportionally \u2500\u2500\u2500 *\/\n  function updateProgress() {\n    Q.progress.style.width = (total \/ session.length * 100) + '%';\n  }\n\n  \/* \u2500\u2500 showScore \u2014 renders the final score panel \u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500 *\/\n  function showScore() {\n    const c  = answered.filter(a => a === 'correct').length;\n    const w  = answered.filter(a => a === 'wrong').length;\n    const sk = answered.filter(a => a === null).length;\n    const mx = session.length * 4;\n    const ns = c * 4 - w;\n    const pc = Math.round(ns \/ mx * 100);\n    const bw = Math.max(0, Math.min(100, pc));\n\n    \/* Performance message based on percentage *\/\n    const msg = pc >= 85 ? 'Outstanding! Excellent command of pacemaker concepts.' :\n                pc >= 65 ? 'Good foundation \u2014 revisit the explanations for gaps.' :\n                pc >= 50 ? 'Passing, but targeted revision is recommended.' :\n                pc >= 0  ? 'Dedicated study needed \u2014 use explanations as concise notes.' :\n                           'Negative net score \u2014 avoid guessing on unfamiliar questions.';\n\n    \/* Score formula: c \u00d7 4 \u2212 w  (no brackets, per house style) *\/\n    Q.score.innerHTML = `\n      <h2>Quiz Complete<\/h2>\n      <div class=\"score-num\">${ns < 0 ? ns : '+' + ns}<\/div>\n      <div class=\"score-denom\">Net Score &nbsp;|&nbsp; Max Marks: ${mx}<\/div>\n      <div class=\"grade-bar\"><div class=\"grade-fill\" style=\"width:${bw}%\"><\/div><\/div>\n      <div class=\"score-breakdown\">\n        <span><strong>${c}<\/strong><br>Correct<br><small>(+${c * 4})<\/small><\/span>\n        <span><strong>${w}<\/strong><br>Wrong<br><small>(\u2212${w})<\/small><\/span>\n        <span><strong>${sk}<\/strong><br>Skipped<br><small>(0)<\/small><\/span>\n        <span><strong>${Math.max(0, pc)}%<\/strong><br>Score%<\/span>\n      <\/div>\n      <div class=\"score-formula\">\n        Net = ${c} \u00d7 4 \u2212 ${w} = <strong>${ns}<\/strong>\n        &nbsp;|&nbsp; ${ns} \u00f7 ${mx} \u00d7 100 = <strong>${pc}%<\/strong>\n      <\/div>\n      <div class=\"score-msg\">${msg}<\/div>\n      <button class=\"btn-retry\" id=\"pm-retry\">\u21ba Reshuffle &amp; Retry<\/button>`;\n\n    Q.score.style.display = 'block';\n    Q.submit.classList.remove('visible');\n    Q.score.scrollIntoView({ behavior: 'smooth' });\n    document.getElementById('pm-retry').addEventListener('click', retryQuiz);\n  }\n\n  \/* \u2500\u2500 retryQuiz \u2014 reshuffles everything and rebuilds from scratch *\/\n  function retryQuiz() {\n    Q.score.style.display = 'none';\n    prepareSession();\n    updateStats();\n    updateProgress();\n    buildQuiz();\n    window.scrollTo({ top: 0, behavior: 'smooth' });\n  }\n\n  \/* \u2500\u2500 Event listeners and initialisation \u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500 *\/\n  Q.submit.addEventListener('click', showScore);\n  prepareSession();\n  buildQuiz();\n  updateStats();\n\n  \/* \u2500\u2500 IntersectionObserver \u2014 shows\/hides fixed status bar \u2500\u2500\u2500\u2500\u2500\u2500\u2500 *\/\n  new IntersectionObserver(\n    ([e]) => document.getElementById('pm-status-bar')\n                      .classList.toggle('visible', !e.isIntersecting),\n    { threshold: 0 }\n  ).observe(document.getElementById('pm-sentinel'));\n\n})(); \/* \u2500\u2500 end IIFE \u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500 *\/\n<\/script>\n<\/div><!-- \/#atsixty-pm-quiz -->\n\n\n","protected":false},"excerpt":{"rendered":"<p>\u2713 0 \u2717 0 Left 15 Net 0 Max 60 View Score \u2192<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"neve_meta_sidebar":"","neve_meta_container":"","neve_meta_enable_content_width":"","neve_meta_content_width":0,"neve_meta_title_alignment":"","neve_meta_author_avatar":"","neve_post_elements_order":"","neve_meta_disable_header":"","neve_meta_disable_footer":"","neve_meta_disable_title":"","footnotes":""},"categories":[24],"tags":[],"class_list":["post-36444","post","type-post","status-publish","format-standard","hentry","category-neet-pg"],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v27.3 - 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