Right ventricular myocardial infarction resident survival guide

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Mitra Chitsazan, M.D.[2] Mandana Chitsazan, M.D. [3]

Overview

RV infarction is a form of ST elevation myocardial infarction (STEMI) and is characterized by the presence of symptoms of myocardial ischemia associated with persistent ST elevation on electrocardiogram in right-sided lead V4 (V4R), and elevated cardiac enzymes, hypotension, signs of elevated right heart filling pressures (elevated jugular venous pressure) in the absence of signs of elevated left heart filling pressures (clear lung fields). Nitrates, diuretics and beta-blockers should not be administered to the patient with an RV MI.

Causes

Life Threatening Causes

STEMI is a life-threatening condition and must be treated as such irrespective of the underlying cause.

Common Causes

• Plaque rupture
• Aortic dissection with propagation to the right coronary artery
• Cocaine

Diagnosis

Shown below is an algorithm summarizing the diagnosis of Right ventricular myocardial infarction(RV MI) according to the American College of Cardiology and European Society of Cardiology guidelines.

All patients with acute inferior wall myocardial infarction (ST elevation in leads II, III, aVF)

Obtain right-sided precordial leads

>= 1mm ST elevation in lead V4R

Highly suggestive of RVMI

Physical examination

Echocardiography

Coronary Angiography

Hemodynamic study

❑ Classic triad of: ❑ Hypotension ❑ Elevated JVP ❑ Clear Lungs ❑ Kussmaul sign ❑ Pulsus paradoxus ❑ Tricuspid regurgitation murmur ❑ Atrioventrcicular dissociation ❑ Vagal symptoms: Bradycardia ❑ Nausea ❑ Vomiting ❑ Diaphoresis ❑ Pallor

❑ RV dilatation ❑ Depressed RV systolic function ❑ RV wall akinesia or dyskinesia ❑ RA enlargement ❑ Elevated pulmonary pressures ❑ Pulmonary regurgitation ❑ Tricuspid regurgitation ❑ Increased right atrial pressure

Gold standard diagnostic modality ❑ In the majority of RVMI: ❑ The culprit artery: Proximal Right Coronary Artery ❑ Occasionally: ❑ The culprit artery: Left circumflex artery or left anterior descending artery

❑ Hemodynamically significant RVMI: ❑ Increased RAP>10 mmHg ❑ RAP to PCWP ratio >0.8 (normal<0.6) ❑ RAP within 5 mmHg of the PCWP ❑ Reduced cardiac index ❑ Disproportionate elevation of right-sided filling pressures: Hallmark of RVMI ❑ In concomitant LV dysfunction: ❑ RAP to PCWP ratio can change ❑ Additional hemodynamic changes: ❑ Prominent Y-descend of the RAP ❑ Drop of the systemic arterial pressure >10 mmHg with inspiration ❑ "Dip and plateau" morphology and equalization of the diastolic filling pressures

Treatment

Shown below is an algorithm summarizing the treatment of Right ventricular myocardial infarction according to the American College of Cardiology and European Society of Cardiology guidelines.

Therapuetic Considerations in Right Ventriculay Myocardial Infarction (RV MI)

Reperfusion

Maintenance of RV preload

Decreasing RV afterload

Restoring Rate/Rhythm and AV synchrony

Inotropic support

Mechanical Circulatory Support

❑Thrmobolytics ❑Percutaneous coronary intervention (PCI)

❑ Avoidance of preload-reducing agents, such as: ❑ Nitrates ❑ Diuretics ❑ Morphin ❑ In patients with hypotension (without pulmonary congestion): ❑ Intravenous administration of Fluids (N/S 0.9% at 40mL/min for up to 2L, to maintain CVP <15 mmHg and PCWP between 18-24 mmHg)

❑ Systemic or pulmonary vasodilators: ❑ Nitrosrusside ❑ Inhaled nitric oxide

❑ In patients with bradyarrhthmias: ❑ Atropine ❑ Pacemaker ❑ In patients with atrioventricular block: ❑ Temporary dual-chamber pacemaker

In patients with refractory hypotension: ❑ Dobutamine (along with fluids) ❑ Other inotropes: ❑ Milrinone ❑ Norepinephrine

❑ May be needed in patients with cardiogenic shock secondary to RV MI: ❑ Direct RV support ❑ Indirect RV support ❑ Biventricular support

Do's

• Right ventricular myocardial infarction (RV MI) should be ruled out in all patients presenting with acute inferior wall myocardial infarction, in particular in patients with hypotension.

• In patients presenting with chest pain and clinical findings of hypotension, elevated JVP and clear lung fields, consider the differential diagnoses of RV MI. These include:
  • Pulmonary embolism
  • Pericarditis with pericardial tamponade

• Systemic or pulmonary vasodilators may be considered in selected patients to reduce RV afterload, thereby improving cardiac output.

• In patients with severe tricuspid regurgitation due to RVMI, replacement of tricuspid valve or repair of the valve with annuloplasty rings may be considered.

• In patients with RVMI who have unexplained hypoxemia despite administration of 100% oxygen, right-to-left shunting -through a patent foramen ovale or atrial septal defect-, caused by the disproportionate elevation in right-sided filling pressures compared to the normal or slightly increased left-sided filling pressures should be considered.

• Patients with extensive necrosis due to RV MI may be at higher risk of right ventricular perforation during interventional procedures. Right ventricular catheterization or pacemaker insertion should be performed with great care in these patients.

Don'ts

• In patients with RV MI, avoid preload-reducing agents such as nitrates, diuretics, morphine, beta-blockers, and calcium channel blockers.

References

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