Isolated Tricuspid Regurgitation Alternans in Acute Myocardial Infarction: A Rare Entity.

Pulsus alternans is characterized by alternating strong and weak beats, and occurs with failing hearts. Left ventricular pulsus alternans is known to occur with ischemic heart disease, valvular heart disease, and outflow tract obstructions. Isolated right ventricular (RV) pulsus alternans is a rare entity. We report the case of a 51-year-old male patient who presented with inferior wall myocardial infarction and cardiogenic shock. He was diagnosed to have an isolated tricuspid regurgitation alternans signifying severe RV dysfunction. The patient was resuscitated and treated with primary percutaneous intervention to the right coronary artery. We also review the literature associated with RV pulsus alternans and its mechanisms. Copyright:

INTRODUCTION

Pulsus alternans is an enigmatic entity that is known to occur with failing hearts. It is usually appreciated clinically with palpation of the radial pulses and signifies a reduced left ventricular systolic function. However, rarely an isolated right ventricular (RV) pulsus alternans may occur in the setting of RV dysfunction. Such discordant RV alternans can be associated with significant hemodynamic compromise. We describe a case of tricuspid regurgitation alternans detected on echocardiographic examination in the setting of RV myocardial infarction and review the literature associated with this condition in brief.

CASE REPORT

A 51-year-old male patient presented to the cardiology emergency room with chest heaviness and diaphoresis for 3 h. He was a known diabetic on long-acting insulin therapy and a smoker. The patient was pale with severe hemodynamic compromise. His blood pressure was 70/20 mmHg. An urgent ECG was obtained which revealed an acute inferior wall myocardial infarction [Figure 1]. An urgent echocardiography was performed which revealed hypokinetic inferior and inferior septal walls of the left ventricle. There was associated RV myocardial infarction with tricuspid annular plane systolic excursion of 10 mm. The patient had a moderate tricuspid regurgitation. However, the tricuspid regurgitation velocity showed marked beat-to-beat variation, alternating with every alternate beat suggestive of tricuspid regurgitation alternans [Figure 2].

Figure 1

Electrocardiography of the patient showing inferior wall myocardial infarction

Figure 2

Echocardiography image depicting right ventricular alternans

The patient was rapidly infused with intravenous fluids. Inotropic support was started and the patient was immediately taken up for revascularization as a primary percutaneous coronary intervention case. Coronary angiography revealed an occluded right coronary artery which was stented using a drug-eluting stent. His hemodynamics improved with subsequent disappearance of the pulsus alternans. The postoperative period of the patient was uneventful, and he was discharged 2 days later.

The patient provided written consent for this manuscript.

DISCUSSION

As many as 30%–50% of patients with inferior wall infarct can have associated RV infarctions.[1] In these cases, the culprit artery is most often an occluded right coronary artery, as seen in our case.

Pulsus alternans, first described by Traube in 1872, secondary to left ventricular systolic dysfunction is a widely known entity. Other causes of left ventricular alternans include coronary artery disease, mitral stenosis, prosthetic valve dysfunction, transient ischemia, dobutamine infusion, and outflow tract obstruction (aortic stenosis and hypertrophic cardiomyopathy).[2]

Biventricular alternans has uncommonly been described in the literature where RV alternans accompanies left ventricular alternans. Most of these patients are known to have severe left ventricular systolic dysfunction with accompanying RV involvement. It is known as synchronous or concordant in these cases.[12]

Pulsus alternans is known as discordant mechanical alternans when it occurs isolated in the pulmonary or the systemic circulation. Isolated RV alternans is a rare entity and has been reported to occur in mitral stenosis, chronic obstructive pulmonary disease, primary pulmonary hypertension, and pulmonary embolism.[34]

Isolated RV infarction is known to occur in <3% autopsies revealing infarction.[34] In our case, the patient had tricuspid regurgitation alternans which was consistent with severe RV myocardial infarction and RV systolic dysfunction.

Two mechanisms have been proposed to explain the occurrence of pulsus alternans. The first theory assumes that a reduced stroke volume secondary to impaired contraction of a dysfunctional ventricle leads to elevated end-diastolic volumes in the next beat. This leads to a stronger contraction as per Frank–Starling mechanism. The second theory explains pulsus alternans on the basis of delayed uptake and release of calcium from the sarcoplasmic reticulum. This change in calcium cycling leads to development of pulsus alternans.[5]

RV function has traditionally been difficult to assess with echocardiography. Annular indices such as tricuspid annular excursion or S' velocity are unreliable and insensitive. Imaging the RV along its major axis is a challenge, and RV contractility does not necessarily equate with ventricular dysfunction. Furthermore, tricuspid regurgitation depends on volumetric metrics and can overestimate RV function.[6] The presence of RV alternans can signify a significant damage to RV myocardium and should be taken into account when evaluating RV function.

Pulsus alternans is an enigmatic entity that occurs with failing ventricles. However, isolated RV alternans has been rarely reported in the literature. Our case demonstrates objectively by means of echocardiography a clear case of tricuspid alternans in the setting of RV myocardial infarction.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient has given his consent for his images and other clinical information to be reported in the journal. The patient understands that name and initials will not be published and due efforts will be made to conceal his identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.