ACS -Advanced: Mechanical Complications & Shock — 40 Interactive MCQs
ACS -Advanced: Mechanical Complications & Shock — 40 Interactive MCQs
1. A 62-year-old man 3 days after an extensive anterior MI develops sudden hypotension, muffled heart sounds, and jugular venous distension. What is the most likely diagnosis?
Free wall rupture leads to hemopericardium and tamponade—acute hypotension, muffled heart sounds, JVD (Beck’s triad) are classic.
2. A patient day 5 post-MI develops a new harsh holosystolic murmur, acute pulmonary edema and a left-to-right shunt on echo. Which complication is most likely?
VSR produces a new harsh pansystolic murmur and acute left-to-right shunt causing pulmonary edema; commonly occurs days after transmural MI.
3. On bedside echo of a suspected mechanical complication, which finding indicates tamponade physiology?
Diastolic collapse of the right-sided chambers with effusion indicates tamponade physiology and is an indication for urgent drainage.
4. A 70-year-old woman post-inferior MI has acute hypotension and clear lung fields. On exam, there is elevated JVP and Kussmaul sign. What is the likely cause?
Inferior MI can involve the RV—RV infarction causes hypotension with clear lungs, JVD, and Kussmaul sign due to poor RV filling.
5. A patient in the cath lab develops sudden profound hypotension and pulseless electrical activity immediately after reperfusion. Which mechanical catastrophe should you suspect?
Free wall rupture classically causes sudden tamponade and PEA arrest; immediate bedside echo/ pericardiocentesis may be life-saving if reversible.
6. A hemodynamically unstable patient with VSR after MI—what is the definitive management?
VSR requires urgent mechanical correction—surgical repair is definitive; percutaneous closure may be considered in select patients as bridge or alternative.
7. Which hemodynamic profile is typical of cardiogenic shock due to pump failure?
Cardiogenic shock shows low cardiac output, elevated SVR (compensatory), and increased filling pressures (high PCWP/LVEDP).
8. A patient with acute MR due to papillary muscle rupture has severe pulmonary edema and hypotension. Which immediate step is most appropriate before definitive surgery?
Acute severe MR often requires hemodynamic stabilization (afterload reduction, support) and urgent surgical correction of the ruptured papillary muscle.
9. Which echo feature best differentiates papillary muscle rupture (acute MR) from VSR?
Flail leaflet or visible pap muscle rupture and eccentric MR jet on echo indicates papillary muscle rupture; VSR shows a septal defect with shunt flow.
10. A 58-year-old post-MI in cardiogenic shock: pulmonary capillary wedge pressure (PCWP) is high, cardiac index is low. Which therapy improves cardiac output with less increase in afterload?
Dobutamine increases inotropy and cardiac output with modest effect on afterload; vasopressors primarily raise SVR and may worsen afterload.
11. Which mechanical support device directly unloads the left ventricle and can reduce PCWP?
Devices like IABP (modestly) and Impella actively unload the LV and can decrease PCWP; peripheral VA-ECMO may increase afterload unless LV vented.
12. A patient with cardiogenic shock on high-dose inotropes has worsening pulmonary edema. Which next step should be considered to improve oxygenation and cardiac unloading?
In worsening shock with pulmonary edema despite inotropes, MCS and ventilatory support may be required; increasing inotropes may raise myocardial O₂ demand and be harmful.
13. After reperfusion, a patient develops recurrent chest pain, hypotension, and new ST-elevation — what should be suspected?
Recurrent ischemia and ST-elevation after PCI suggests re-occlusion or acute stent thrombosis and requires immediate angiographic assessment.
14. Which lab trend helps distinguish reinfarction from persistent troponin elevation after a recent MI?
Reinfarction is suggested by a new upward trend in cardiac biomarkers (troponin) after stabilization or decline.
15. In VSR, what hemodynamic finding is expected on right heart catheterization?
VSR causes left-to-right shunt producing an oxygen saturation ‘step-up’ in the RV compared to RA on catheterization.
16. A patient with acute tamponade from free wall rupture—what is the best immediate bedside procedure?
Pericardiocentesis relieves tamponade and can stabilize the patient temporarily before definitive surgical repair.
17. Which clinical sign differentiates papillary muscle rupture (acute MR) from chronic MR?
Acute pap muscle rupture causes abrupt severe MR with pulmonary edema and hypotension, unlike chronic MR which progresses gradually.
18. In cardiogenic shock due to LV failure, which monitoring is most helpful to titrate therapy?
Invasive hemodynamics help guide inotrope/vasopressor selection, MCS timing, and fluid management in complex shock patients.
19. Which of the following increases left ventricular afterload and may worsen pulmonary edema when used alone in cardiogenic shock?
Pure alpha agonists like phenylephrine raise SVR/afterload and can worsen pulmonary edema in LV failure; choose agents that increase contractility or reduce afterload carefully.
20. A patient with multi-organ hypoperfusion and refractory shock despite inotropes—what is the role of VA-ECMO?
VA-ECMO provides systemic perfusion and oxygenation in refractory shock as bridge therapy but does not replace the need for definitive revascularization or repair.
21. Which parameter defines cardiogenic shock most directly?
Cardiogenic shock is hypotension with end-organ hypoperfusion due to primary cardiac dysfunction and reduced cardiac output.
22. A 65-year-old with acute anterior MI shows new VSR on echo. He is hemodynamically stable. What is recommended timing for surgery?
Surgical repair is generally indicated—timing depends on hemodynamics; unstable patients need urgent repair; some stable patients may be bridged to optimal timing.
23. In cardiogenic shock, which combination is preferred to maintain coronary perfusion pressure while supporting BP?
Norepinephrine maintains MAP with less tachyarrhythmia; add inotrope to improve cardiac output when required.
24. A patient with post-MI mechanical complication is too unstable for immediate surgery. What temporizing measures may be used?
MCS devices can stabilize circulation and oxygenation to allow transfer or optimization before definitive surgical repair.
25. Which of the following is the classic time-window for occurrence of papillary muscle rupture after MI?
Pap muscle rupture commonly occurs in the subacute period (2–7 days) when necrotic tissue weakens the papillary muscle or its insertion.
26. Which complication is more likely after inferior MI than anterior MI?
Inferior MI frequently involves the RV and conduction system, predisposing to RV failure and high-degree AV block.
27. A 59-year-old with post-MI shock has high PCWP and low CI. After initiating IABP, what hemodynamic improvement is expected?
IABP provides modest hemodynamic support (afterload reduction and better coronary perfusion) but not large increases in cardiac output.
28. Which clinical scenario is most consistent with development of ventricular aneurysm post-MI?
Ventricular aneurysms develop over weeks–months after transmural infarct and present with progressive heart failure and dyskinetic LV wall motion.
29. In an unstable patient with suspected post-MI mechanical complication, which imaging is fastest at the bedside?
Bedside transthoracic echo is rapid, non-invasive, and essential to evaluate mechanical complications and tamponade.
30. A patient who had RCA occlusion presents with hypotension and clear lungs; echo confirms RV dilation and dysfunction. What is the initial management?
RV infarction causes preload dependence—careful IV fluids to optimize preload and prompt revascularization are indicated; diuretics can worsen hypotension.
31. Which of the following best predicts survival in cardiogenic shock after reperfusion?
Timely revascularization and rapid escalation to mechanical support when necessary are key determinants of survival in post-MI shock.
32. A patient has acute severe MR with hypotension; vasodilators would:
Vasodilators reduce afterload and can transiently improve forward flow in acute MR if the patient is not severely hypotensive; definitive surgery is usually required.
33. A patient with large anterior MI develops progressively worsening oliguria and metabolic acidosis despite fluids—what is the likely mechanism?
Low cardiac output leads to renal hypoperfusion and cardiorenal syndrome—improving cardiac output is central to treatment.
34. Which characteristic of a VSR on physical exam helps differentiate it from papillary muscle rupture?
VSR often produces a loud, harsh pansystolic murmur with a palpable thrill at the left sternal border; MR murmur radiates to the axilla.
35. After initiating VA-ECMO for refractory cardiogenic shock, the patient develops rising LVEDP and pulmonary edema. Why does this occur and what is the remedy?
Peripheral VA-ECMO can increase LV afterload causing distension and pulmonary edema; LV unloading strategies are required (IABP, Impella, or surgical venting).
36. A patient with suspected mechanical complication has hypotension and new murmur; which immediate test will best guide urgent management?
Bedside TTE rapidly identifies tamponade, VSR, pap muscle rupture, and severe MR and is essential for immediate decision-making.
37. Which of the following best describes management priorities for a patient with mechanical complication and multi-organ failure?
Critical patients require urgent multidisciplinary care including MCS to stabilize end-organ perfusion prior to definitive surgical management when possible.
38. Which antibiotic prophylaxis consideration is relevant before urgent repair of mechanical complication in a post-MI patient?
Urgent cardiac surgery requires standard perioperative antibiotic prophylaxis to reduce surgical-site and mediastinal infections.
39. Which factor most strongly influences candidacy for heart transplantation in a patient who had mechanical complications and persistent severe LV dysfunction?
Transplant candidacy requires assessment of multi-organ function, control of infection, psychosocial factors, and potential for rehabilitation, not any single factor.
40. Which best describes the overall approach to a patient with post-MI mechanical complication presenting with shock?
Time-sensitive approach: confirm the lesion, stabilize hemodynamics (MCS if required), and proceed to definitive repair promptly—this maximizes survival.
50 Advanced FAQs — Mechanical Complications of MI & Shock (DM Cardiology Level)
1. What are the earliest warning signals for an impending LV free wall rupture?
- Persistent or recurrent chest pain after PCI or thrombolysis.
- Sudden hypotension with electromechanical dissociation.
- New pericardial effusion with echogenic clot.
- Rapidly rising JVP with pulseless electrical activity.
- ST elevation recurrence after initial resolution.
2. How does papillary muscle rupture typically present?
- Sudden severe pulmonary edema.
- Flash cardiogenic shock despite preserved EF.
- Harsh holosystolic murmur radiating to axilla or back.
- Hyperdynamic LV on echo with flail leaflet.
- Large V-waves and rapid y-descent on PCWP tracing.
3. What distinguishes papillary muscle rupture from functional ischemic MR?
- Acute rupture: abrupt hemodynamic collapse; functional MR: gradual.
- Acute rupture: flail leaflet on echo; functional MR: tethered leaflets.
- Acute rupture: chordal discontinuity; functional MR: annular dilatation.
- LV function preserved in rupture; depressed in functional MR.
- Severe eccentric jet in rupture; central jet in functional MR.
4. Key differentiators between ventricular septal rupture (VSR) and acute MR in shock?
- VSR: biventricular failure; MR: predominantly pulmonary congestion.
- VSR: harsh systolic murmur with thrill; MR: softer apical murmur.
- VSR: O2 step-up in RV; MR: large V-waves in PCWP.
- VSR: equalization of RV/LV pressures; MR: normal RV pressure gradients.
- VSR: hyperdynamic LV; MR: variable LV function.
5. What are echo hallmarks of acute VSR?
- Color Doppler jet crossing septum.
- High-velocity left-to-right shunt.
- Hyperkinetic non-infarcted LV walls.
- RV shock morphology: dilation + dysfunction.
- Incomplete septal necrosis in early imaging.
6. What conditions mimic post-MI VSR?
- Congenital VSD unmasked during MI.
- Post-infarct pseudoaneurysm with ruptured neck.
- Acute MR with eccentric jet.
- High-flow MR causing RV volume overload.
- Ruptured right-ventricular infarcted wall creating false VSD.
7. When should PCI be used before surgery in mechanical complications?
- Ongoing ischemia in non-infarct borders.
- Cardiogenic shock with culprit lesion treatable rapidly.
- To stabilize before surgical correction.
- When MCS cannot be deployed without revascularization.
- PCI only if it will not delay surgery.
8. Hemodynamic profile of cardiogenic shock due to RV infarction?
- Elevated JVP with clear lungs.
- Hypotension with low LV filling pressures.
- Kussmaul sign.
- RV dilation on echo with McConnell pattern sometimes.
- High sensitivity to preload and rhythm disturbances.
9. What is the role of right-sided ECG leads in shock evaluation?
- Detect RV infarction missed by standard ECG.
- Guide volume management decisions.
- Predict need for temporary pacing.
- Identify proximal RCA occlusions.
- Prevent inappropriate nitrates/diuretics.
10. Why does LV free wall rupture peak on day 3–5 after MI?
- Macrophage-mediated structural digestion.
- Loss of tensile strength in infarct zone.
- Mechanical stretching by intact myocardium.
- Absence of robust scar formation.
- Higher wall stress due to elevated BP or tachycardia.
11. How is pseudoaneurysm different from true aneurysm?
- Narrow neck vs wide neck.
- High rupture risk vs low rupture risk.
- Rupture contained by pericardium vs myocardium.
- Turbulent flow on Doppler vs laminar.
- URGENT surgical repair vs elective.
12. Indications for urgent surgery in post-MI VSR?
- Persistent shock despite IABP.
- Large defect (>15 mm) with high shunt fraction.
- Rapidly increasing lactate.
- Worsening RV dysfunction.
- Recurrent arrhythmias from hemodynamic collapse.
13. How does Impella support post-MI MR or VSR?
- Reduces LV afterload.
- Decreases regurgitant volume.
- Improves forward cardiac output.
- Lowers LVEDP reducing pulmonary edema.
- Stabilizes for definitive surgery.
14. When is ECMO superior to IABP in mechanical complications?
- Profound biventricular failure.
- Refractory hypoxemia with pulmonary edema.
- Cardiac arrest/post-resuscitation.
- Severe lactic acidosis.
- Inadequate perfusion despite dual inotropes.
15. Why is early VSR surgery associated with high mortality?
- Friable septal tissue.
- Failure of sutures to hold necrotic myocardium.
- Persistent shunt post-surgery.
- Multi-organ dysfunction before repair.
- Need for extensive patch reconstruction.
16. Role of Sgarbossa criteria in diagnosing post-MI mechanical complications?
- Differentiate new LBBB vs infarct complications.
- Helps detect early transmural ischemia leading to rupture.
- Predicts risk of larger infarct size.
- Correlates with deeper wall injury.
- Guides urgency of reperfusion.
17. Factors predicting LV free wall rupture?
- First MI, especially anterior.
- Late reperfusion.
- Persistent hypertension.
- Thrombolysis without PCI.
- Older age and female sex.
18. Which mechanical complication presents with sudden electromechanical dissociation?
- LV free wall rupture.
- Tamponade from hemopericardium.
- Catastrophic RV rupture.
- Papillary muscle rupture with acute severe MR.
- Massive pulmonary embolism differential.
19. Why does papillary muscle rupture more often affect the posteromedial head?
- Single blood supply (PDA).
- Higher ischemic vulnerability.
- No collateral flow.
- Inferior MI predominance.
- Anterolateral has dual supply; less rupture.
20. How do you differentiate pseudoaneurysm from contained LV rupture on echo?
- Pseudoaneurysm: narrow neck <50% diameter.
- Absence of myocardium in walls.
- To-and-fro flow.
- Pericardial tethering.
- High wall stress and rupture risk.
21. When should fibrinolysis be avoided in suspected mechanical complications?
- Free wall rupture suspicion.
- Large VSR murmur with instability.
- Suspected hemopericardium.
- Acute severe MR with shock.
- Extreme frailty or delayed presentation.
22. CT findings of post-MI LV rupture?
- Pericardial hematoma.
- Discontinuity of LV myocardium.
- Active extravasation of contrast.
- Pseudoaneurysm neck visualization.
- Compression of RV from tamponade.
23. Predictors of VSR severity?
- Anterior MI.
- Delay to reperfusion.
- Complete LAD occlusion.
- Extensive septal necrosis.
- High systolic pulmonary pressures.
24. Hemodynamic clues to post-MI VSR on catheterization?
- RV oxygen step-up >8%.
- Equalization of RV and LV systolic pressures.
- Large left-to-right shunt (Qp/Qs > 1.5).
- Elevated RVEDP.
- Hyperdynamic LV pressure tracing.
25. What is the pathophysiology of acute MR causing shock?
- Abrupt regurgitant volume → ↑LA pressure.
- Flash pulmonary edema.
- Reduced forward stroke volume.
- Reflex tachycardia increasing oxygen demand.
- Secondary RV dysfunction.
26. Use of IABP in VSR?
- Reduces afterload.
- Decreases shunt fraction.
- Improves forward flow.
- Stabilizes for surgery.
- Mandatory in most cases pre-op.
27. When is Impella contraindicated?
- LV thrombus.
- Mechanical aortic valve.
- Severe aortic stenosis.
- VSR with hemodynamically unstable RV.
- Severe PAD preventing large-bore access.
28. What echo finding suggests basal VSR?
- Posterior septal defect.
- Dilated RV with apical sparing.
- Eccentric jet directed anteriorly.
- Harder to visualize; may need TEE.
- Often associated with inferior MI.
29. Clues to diagnose acute severe MR without murmur?
- Low cardiac output state reducing jet.
- Rapid equalization of LA/LV pressures.
- Minimal turbulence.
- Soft or absent murmur.
- Flash pulmonary edema disproportionate to murmur.
30. Why is bedside echo essential in cardiogenic shock?
- Identifies mechanical lesions immediately.
- Guides MCS choice.
- Detects RV failure vs LV failure.
- Assesses volume responsiveness.
- Rules out tamponade, PE.
31. What are the five major mechanical complications of MI?
- LV free wall rupture.
- Ventricular septal rupture.
- Papillary muscle rupture.
- True aneurysm.
- Pseudoaneurysm.
32. When does pseudoaneurysm require surgery?
- Always unless prohibitive risk.
- High rupture risk.
- Symptomatic.
- Expanding on imaging.
- Hemodynamic compromise.
33. What is the typical timing of mechanical complications after MI?
- Papillary muscle rupture: 2–7 days.
- Free wall rupture: 3–5 days.
- VSR: 3–7 days.
- True aneurysm: weeks to months.
- Pseudoaneurysm: anytime post-MI.
34. What is the shock index and its value in ACS?
- HR/SBP ratio.
- 0.9 predicts shock.
- Useful in prehospital triage.
- Correlates with infarct size.
- Helps early MCS decisions.
35. Unique signs of RV infarction–induced shock?
- Clear lungs.
- Hypotension with bradycardia.
- ST elevation in V4R.
- Worsening with nitrates.
- Marked preload sensitivity.
36. What factors predict poor outcome in cardiogenic shock?
- Lactate >5 mmol/L.
- pH <7.2.
- Multi-organ failure.
- Prolonged ischemia before reperfusion.
- Refractory arrhythmias.
37. How to differentiate pericardial effusion vs tamponade in post-MI?
- Effusion: stable vitals.
- Tamponade: hypotension + pulsus paradoxus.
- RV diastolic collapse.
- Equalized diastolic pressures.
- Dilated IVC without collapse.
38. When to suspect contained rupture after PCI?
- Sudden severe pain during dilation.
- Rapid pericardial effusion.
- Hypotension disproportionate to procedure.
- Angiographic dye outside lumen.
- DROP in LVEDP abruptly.
39. Mechanism of shock in VSR?
- Massive left-to-right shunt.
- RV overload → RV failure.
- Reduced LV output.
- Hypotension and lactic acidosis.
- Worsened by tachycardia.
40. What is the mortality difference between early vs delayed VSR repair?
- Early (<24h): highest mortality.
- Delayed (3–7 days): lower.
- Delay allows infarct healing.
- But risk of deterioration is high.
- MCS bridges allow delayed repair.
41. Management of acute MR with refractory shock?
- Emergent surgical repair.
- IABP or Impella.
- Avoid afterload-increasing drugs.
- Diuretics cautiously.
- Secure airway early.
42. What is the “triad of free wall rupture”?
- Sudden hypotension.
- Pulseless electrical activity.
- Rapid pericardial tamponade.
Often preceded by: persistent chest pain.
43. Best imaging modality for early detection of pseudoaneurysm?
- TEE superior to TTE.
- CT when echo suboptimal.
- MRI for wall characterization.
- Angiography for neck clarity.
- Echo contrast enhances definition.
44. Role of serial lactate monitoring in shock?
- Marker of perfusion.
- Guides resuscitation success.
- Poor prognostic indicator if rising.
- Helps decide escalation to ECMO.
- Clearance correlates with survival.
45. Why is dobutamine risky in mechanical complications?
- Increases myocardial oxygen demand.
- Aggravates MR/VSR flow.
- Precipitates arrhythmias.
- May worsen hypotension.
- Should be used only as bridge.
46. Indications for placing IABP before PCI in shock?
- Mechanical complications expected.
- Severe MR or VSR causing hypotension.
- High LVEDP.
- Low cardiac index <1.8 L/min/m².
- Anticipated difficulty in PCI.
47. What is “double rupture syndrome”?
- Coexistence of free wall rupture + VSR.
- Often sequential events.
- High mortality.
- Requires emergent surgery.
- Often diagnosed late.
48. How to optimize RV preload in RV shock?
- Give small fluid boluses (250–500 mL).
- Maintain sinus rhythm.
- Avoid nitrates and diuretics.
- Use norepinephrine for MAP.
- Consider inhaled nitric oxide.
49. Why does inferior MI lead to bradyarrhythmias in shock?
- Vagal stimulation.
- SA node ischemia.
- AV nodal ischemia.
- RCA dominance in conduction system.
- Reperfusion arrhythmias.
50. What is the hierarchy of MCS escalation in cardiogenic shock?
- IABP for afterload reduction.
- Impella for LV unloading.
- ProtekDuo for RV support.
- TandemHeart for left atrial bypass.
- VA-ECMO for full cardiopulmonary support.
