A patient had an acute coronary syndrome 5 days ago and now presents with hypotension, tachycardia, and a new holosystolic murmur radiating to the right sternal border. Which mechanical complication is most likely: free‑wall rupture, ventricular septal rupture, or pseudoaneurysm?

Ventricular Septal Rupture (VSR)

The patient most likely has ventricular septal rupture (option B), based on the timing (day 5 post-ACS), new pansystolic murmur radiating to the right sternal border, and acute hemodynamic deterioration with hypotension and tachycardia. 1, 2

Clinical Reasoning

Timing of Mechanical Complications

• VSR typically occurs 3–7 days post-MI, with day 5 falling squarely in this high-risk window 1, 2
• Free-wall rupture predominantly occurs within the first 24 hours after MI, especially in patients receiving fibrinolytic therapy 2
• Pseudoaneurysm represents a contained rupture that develops over days to weeks and presents with a more subacute, stable course rather than acute hemodynamic collapse 3, 4

Murmur Characteristics Are Diagnostic

• VSR produces a harsh holosystolic murmur that radiates along the sternal border (particularly the right sternal border) due to turbulent left-to-right shunt flow across the ventricular septum 1, 2
• This radiation pattern is pathognomonic for VSR because the defect is typically located in the interventricular septum, directing flow toward the right ventricle and right sternal border 2
• Up to 50% of VSR patients may have a soft or absent murmur due to severe hemodynamic compromise, but when present, the sternal border radiation is highly specific 2

Hemodynamic Presentation

• Sudden hemodynamic deterioration with hypotension, tachycardia, and pulmonary congestion is the hallmark of VSR 1, 2
• The left-to-right shunt reduces effective cardiac output while increasing pulmonary blood flow, causing cardiogenic shock 1
• Patients often mimic reinfarction with recurrent chest pain and ST-segment re-elevation 1, 2

Why Not the Other Options?

Free-Wall Rupture (Option A)

• Acute free-wall rupture is characterized by cardiovascular collapse with electromechanical dissociation (continuing electrical activity but no pulse) and is usually fatal within minutes 1
• Subacute free-wall rupture (25% of cases) presents with cardiac tamponade—jugular venous distension, muffled heart sounds, pulsus paradoxus—rather than a new murmur 1
• The presence of a pansystolic murmur radiating to the sternal border excludes free-wall rupture, which does not produce a murmur 1, 2

Pseudoaneurysm (Option C)

• Pseudoaneurysm represents a contained rupture with thrombus or pericardial adhesions sealing the defect 3, 4
• These patients are typically hemodynamically stable or only mildly symptomatic, not presenting with acute shock 3, 4
• Pseudoaneurysm may go unrecognized and be diagnosed incidentally on imaging weeks to months later 3
• The acute presentation with new murmur and shock on day 5 is inconsistent with pseudoaneurysm 3

Immediate Diagnostic Approach

• Urgent transthoracic echocardiography to visualize the ventricular septal defect and assess shunt severity 1, 2
• Look for color Doppler evidence of left-to-right flow across the interventricular septum 2
• Right-heart catheterization demonstrating an oxygen step-up at the right-ventricular level confirms the diagnosis 1, 2
• Consider transesophageal echocardiography if transthoracic windows are inadequate 2

Immediate Management

Hemodynamic Stabilization

• Insert an intra-aortic balloon pump (IABP) immediately to reduce left-to-right shunt fraction and stabilize hemodynamics as a bridge to surgery 1, 2, 5
• Initiate dobutamine infusion at 5–10 µg·kg⁻¹·min⁻¹ for inotropic support 1, 2
• Target pulmonary wedge pressure ≥15 mm Hg and cardiac index >2 L·min⁻¹·m⁻² 1, 2
• Add vasodilators (nitroglycerin) if blood pressure permits to reduce afterload and shunt fraction 2

Definitive Treatment

• Urgent surgical repair is mandatory even in hemodynamically stable patients because the defect can enlarge abruptly, precipitating sudden collapse 1, 2, 5
• Surgical repair should be combined with coronary artery bypass grafting when feasible 1, 2
• Without surgical intervention, mortality reaches 54% within the first week and 92% within one year 1, 2
• Operative mortality ranges from 20% to 87%, varying with patient condition and defect location 2, 5

Critical Pitfalls

• Do not delay echocardiography when mechanical complications are suspected 2
• Do not rely on medical therapy alone—it results in near-100% mortality for VSR 1, 2, 5
• Transfer immediately to a high-volume cardiac surgical center with multidisciplinary expertise, as higher surgical volume correlates with lower mortality 2, 5
• Hemodynamic deterioration can be abrupt and unpredictable—even stable-appearing patients require urgent surgical consultation 1, 2