What is the best course of action for an elderly female patient with a 15-day history of inferior wall myocardial infarction (MI) with right ventricular myocardial infarction (RVMI) who now presents with vomiting and hypotension, but remains asymptomatic?

Management of Delayed Inferior Wall MI with RVMI Presenting with Hypotension and Vomiting

This patient requires immediate aggressive IV fluid resuscitation with normal saline as first-line therapy, followed by inotropic support with dobutamine (not dopamine) if hypotension persists after adequate volume loading, while strictly avoiding nitrates, diuretics, and morphine which can precipitate cardiovascular collapse in right ventricular infarction. 1

Immediate Diagnostic Confirmation

• Obtain right-sided ECG leads (V3R and V4R) immediately to confirm ongoing RV involvement, though ST elevation may have resolved given the 15-day timeline (50% resolve within 10 hours) 1
• Perform bedside echocardiography to assess RV function, size, and exclude mechanical complications (ventricular septal defect, papillary muscle rupture, free wall rupture) that could explain delayed decompensation 1, 2
• Examine jugular venous pressure - the clinical triad of hypotension, clear lung fields, and elevated JVP is specific (though only 25% sensitive) for RV infarction 1

Critical Pathophysiology Understanding

The vomiting likely represents vagal stimulation or volume depletion that has unmasked the preload-dependent hemodynamics of RV infarction 1. The ischemic right ventricle cannot generate adequate output without optimal preload, and any reduction in venous return (from vomiting, volume depletion, or medications) causes profound hypotension despite the patient appearing "asymptomatic" 1. This represents a high-risk situation with 25-30% mortality risk compared to 6% in uncomplicated inferior MI 1, 3.

Immediate Management Algorithm

Step 1: Aggressive Volume Resuscitation

• Administer IV normal saline boluses rapidly (500-1000 mL over 15-30 minutes initially) to optimize RV preload 1, 3
• Target right atrial pressure ≥10 mmHg and systolic blood pressure >90 mmHg 1, 3
• Continue fluid administration until blood pressure stabilizes or signs of volume overload appear (rising JVP, pulmonary congestion) 1

Step 2: Inotropic Support if Volume Loading Fails

• Start dobutamine 2.5-5 mcg/kg/min (NOT dopamine) if cardiac output remains inadequate after volume loading 1, 3
• Titrate up to 20 mcg/kg/min as needed to maintain systolic BP >90 mmHg 1, 3
• Avoid dopamine as first-line agent - dobutamine is specifically recommended for RV infarction with persistent low output 1, 3

Step 3: Address Conduction Abnormalities

• Administer atropine 0.5 mg IV (up to 2.0 mg total) if bradycardia is present and contributing to hypotension 1, 3
• Maintain AV synchrony - consider temporary AV sequential pacing if high-degree heart block develops and is unresponsive to atropine 1

Step 4: Consider Mechanical Support

• Place intra-aortic balloon pump if hypotension persists despite volume loading and inotropic support 1
• Consider right ventricular assist device or percutaneous cardiopulmonary support for refractory cardiogenic shock 2, 4

Critical Medications to AVOID

• Absolutely avoid nitrates (including sublingual nitroglycerin) - can cause catastrophic hypotension by reducing preload 1, 3
• Avoid diuretics - will worsen hypotension by depleting preload 1
• Avoid morphine - can reduce preload and worsen hypotension 5
• Avoid ACE inhibitors acutely - reserved for afterload reduction only if concomitant LV dysfunction is present and patient is stabilized 1

Antiemetic Management

• Administer ondansetron 4-8 mg IV for vomiting control (avoid metoclopramide which can cause hypotension)
• Correct electrolyte abnormalities that may have resulted from vomiting

Monitoring Requirements

• Place pulmonary artery catheter to guide hemodynamic management - right atrial pressure should be ≥10 mmHg and >80% of pulmonary wedge pressure in RV infarction 1
• Continuous cardiac monitoring for arrhythmias (bradycardia, heart block, atrial fibrillation) 1
• Serial echocardiography to assess RV recovery and detect mechanical complications 2, 4

Delayed Presentation Considerations

At 15 days post-MI, this delayed decompensation suggests either:

• Progressive RV dysfunction from ongoing ischemia or stunning 1, 2
• Mechanical complication (late VSD, papillary muscle rupture) - requires urgent echocardiography 1
• Volume depletion from vomiting unmasking marginal RV function 1

Consider coronary angiography if not previously performed, as late revascularization may still benefit patients with viable but stunned myocardium 1, 2, 4

Prognosis and Recovery

• Most patients demonstrate return of normal RV function over weeks to months, suggesting RV stunning rather than irreversible necrosis 1
• Clinical and hemodynamic recovery occurs even in patients with severe initial RV dysfunction 1, 2
• However, in-hospital mortality remains significantly elevated at 25-30% 1, 3, 6

Common Pitfalls

• Treating hypotension with nitrates reflexively - this is the most dangerous error and can cause cardiovascular collapse 1, 3
• Assuming "asymptomatic" means stable - unrecordable blood pressure is a medical emergency regardless of symptoms 1
• Using dopamine instead of dobutamine for inotropic support in RV infarction 1, 3
• Delaying fluid resuscitation while waiting for diagnostic tests 1