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KEY FEATURES

ESSENTIALS OF DIAGNOSIS

  • Symptoms consistent with acute myocardial infarction (MI)

  • ECG changes of acute inferior or posterior ST-segment elevation MI with ≥ 1 mm ST-segment elevation in V3R or V4R

  • Elevated cardiac biomarkers

  • Echocardiographic evidence of right ventricular wall motion abnormalities

  • Hypotension and jugular venous distention with clear lung fields commonly observed

  • In acute inferoposterior MI, a mean right atrial to pulmonary wedge pressure ratio of ≥ 0.8

GENERAL CONSIDERATIONS

  • Right ventricular (RV) involvement in acute inferior MI is common

  • Hemodynamically significant RV dysfunction is uncommon

  • Of patients with acute inferoposterior MI, 20% may have hemodynamically significant RV involvement

  • RV becomes noncontractile

  • Cardiac output may be maintained in the initial phases by passive flow through the RV

  • Right-sided heart pressures are elevated

  • Left heart pressures are normal or minimally increased

CLINICAL PRESENTATION

SYMPTOMS AND SIGNS

  • Chest pain and symptoms of MI

PHYSICAL EXAM FINDINGS

  • Elevated jugular venous distention

  • Hypotension

  • Cold and clammy extremities

  • Cardiogenic shock

  • Steep jugular venous y descent

  • Kussmaul sign

DIFFERENTIAL DIAGNOSIS

  • Hypotension from other causes with inferoposterior MI

  • Pericarditis

  • Pulmonary embolus

  • Aortic dissection

DIAGNOSTIC EVALUATION

LABORATORY TESTS

  • CBC

  • Metabolic panel

  • Arterial blood gases

  • Chest x-ray: usually shows clear lung fields

  • Cardiac troponins I or T

  • Brain natriuretic peptide levels

ELECTROCARDIOGRAPHY

  • Evidence of acute inferior or posterior MI with ST elevation

  • Shows ST elevation with right-sided chest leads V3R and V4R

IMAGING STUDIES

  • Echocardiogram:

    • – Shows RV regional wall motion abnormalities

    • – May show depressed RV systolic function

DIAGNOSTIC PROCEDURES

  • Right heart catheterization shows characteristic hemodynamic findings: steep y descent of right atrial pressure and ratio of mean right atrial to pulmonary capillary wedge pressure of > 0.8

  • Coronary angiogram usually shows occlusion of the right coronary artery or a dominant circumflex coronary artery

TREATMENT

CARDIOLOGY REFERRAL

  • Patients with acute MI should be managed in consultation with a cardiologist

  • Once hypotension occurs, the care should be transferred to a cardiologist

HOSPITALIZATION CRITERIA

  • All acute MI patients have to be hospitalized

  • Patients must be managed in a cardiac intensive care unit

MEDICATIONS

  • Immediate coronary reperfusion

  • IV fluids if left or right atrial pressure is low

  • IV positive inotropic agents such as dobutamine to maintain blood pressure

  • Avoid diuretics and vasodilators

  • Other treatment similar to that for acute ST-segment elevation MI

THERAPEUTIC PROCEDURES

  • Percutaneous coronary intervention

  • Atrioventricular sequential pacing if a pacemaker required

  • Intra-aortic balloon pump for persistent shock

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