What is the diagnosis for a patient with hypotension, bradycardia, and jugular venous distension presenting with substernal chest pain?

Diagnosis: Inferior Myocardial Infarction with Right Ventricular Involvement

The correct diagnosis is A: Inferior myocardial infarction with evidence of right ventricular involvement. This patient presents with the classic clinical triad of right ventricular (RV) infarction: hypotension (BP 90/70 mmHg), clear lung fields, and elevated jugular venous distension (10 cm JVD), combined with bradycardia (pulse 50 bpm) in the setting of acute chest pain 1.

Clinical Recognition of RV Infarction

The clinical triad of hypotension, clear lung fields, and raised jugular venous pressure in a patient with inferior STEMI is highly specific for RV infarction, though it has sensitivity less than 25%. 1, 2 This patient demonstrates all three cardinal features:

• Hypotension (90/70 mmHg) results from reduced RV output leading to decreased left ventricular preload 3
• Clear lung fields distinguish this from left ventricular pump failure, which would cause pulmonary congestion 1
• Elevated JVD (10 cm) reflects elevated right-sided filling pressures and pericardial restraint from acute RV dilation 2, 3

The presence of bradycardia (50 bpm) is characteristic, as sinus bradycardia and AV block commonly accompany inferior MI, particularly with RV involvement 1, 2.

Why Other Options Are Incorrect

Anterior MI (options B and C) would present with tachycardia, not bradycardia, and would show pulmonary congestion with rales if causing hemodynamic compromise. 1 The hemodynamic profile of cardiogenic shock from left ventricular failure includes tachycardia, tachypnea, pulmonary edema, and small pulse pressure—none of which match this presentation 1.

Posterior MI with lateral extension (option D) would not explain the specific triad of hypotension, clear lungs, and elevated JVD. 1 This hemodynamic pattern is pathognomonic for RV involvement in the context of inferior MI 2, 3.

Diagnostic Confirmation

ST-segment elevation ≥1 mm in right precordial lead V4R is the single most predictive ECG finding for RV infarction, with 88% sensitivity and 78% specificity. 2, 3 This lead should be recorded immediately in all cases of inferior STEMI with shock, as ST elevation may resolve within 10 hours of symptom onset 2, 3.

Additional ECG findings supporting RV infarction include Q-waves and ST-segment elevation in V1-V3 1. Kussmaul's sign (paradoxical rise in JVP with inspiration) may be present and is predictive of RV involvement in 81% of cases 2, 4.

Prognostic Implications

RV infarction occurs in up to 50% of inferior MIs, with 10-15% showing classical hemodynamic abnormalities, and significantly increases in-hospital mortality to 25-30% compared to 6% in uncomplicated inferior MI. 2 This identifies a high-risk subgroup requiring priority reperfusion therapy 2, 3.

Critical Management Principles

The treatment strategy for RV infarction differs fundamentally from left ventricular pump failure and requires maintaining RV preload while strictly avoiding vasodilators. 1, 2, 3

Immediate Management Steps:

• Volume resuscitation with IV normal saline (500-2500 mL bolus, then 500 mL/hour) to maintain elevated right-sided filling pressures 2, 3
• Avoid nitrates, diuretics, and ACE inhibitors which reduce preload and can precipitate catastrophic hypotension 1, 2, 3
• Atropine 0.3-0.5 mg IV (up to 1.5-2.0 mg total) for symptomatic bradycardia with hypotension 1, 2
• AV sequential pacing if high-degree heart block is unresponsive to atropine, as atrial contraction is critical for RV filling 2, 3
• Emergency reperfusion with primary PCI as soon as possible, which reduces mortality from >85% to approximately 60% in shock patients 2, 3

If Hypotension Persists After Volume Loading:

• Dobutamine is the preferred inotropic agent when cardiac output fails to increase after adequate volume loading 2, 3
• Dopamine 5-15 µg/kg/min if systolic BP remains <80 mmHg despite fluids 3
• Intra-aortic balloon pump for refractory hypotension despite optimal medical therapy 2, 3

Common Pitfalls

The most dangerous error is administering nitrates to a patient with RV infarction, which causes profound hypotension by reducing preload. 2, 3 The clear lung fields should immediately alert clinicians that this is NOT left ventricular failure requiring diuretics or vasodilators 1.

Hemodynamic monitoring with pulmonary artery catheter is generally required to optimize volume administration, targeting right atrial pressure ≥10 mmHg and >80% of pulmonary wedge pressure. 2, 3 Optimal left ventricular diastolic filling pressure should be maintained at 14-18 mmHg 3.