Discussion: Although thrombus in the left ventricular apex is not an uncommon occurrence its presence in the right ventricle is rare1. There are reports of thrombus in transit, i.e. thrombus originating from deep vein thrombosis detected on its way to the pulmonary tree in the setting of pulmonary embolism2. It is noteworthy that the patient had severe pulmonary hypertension which could partly be explained by the left heart failure and mitral regurgitation, but additional pulmonary embolism must be considered given that the estimated pulmonary artery pressure was more than 80 mm Hg.
Acute myocardial infarction (MI) involving only the right ventricle is an uncommon event. More often, right ventricular infarction (RVMI) is associated with acute ST-elevation myocardial infarction of the inferior wall of the left ventricle since the right coronary artery supplies most of the RV. It occurs in 30 to 50 percent of such cases but is rarely of clinical significance. Involvement of the right ventricle is also recognized in anterior myocardial infarction in pathologic studies. The anterior wall of the RV is supplied by branches of the left anterior descending coronary artery and autopsy studies demonstrated that acute LAD occlusion could also provoke a small RV infarction3. Boukantar et al. reported a patient with anterior myocardial infarction with involvement of the right ventricular apex associated with a thrombus diagnosed by magnetic resonance imaging and evidence of pulmonary embolism4.
Any patient with symptoms of an acute coronary syndrome and electrocardiographic evidence of inferior wall ischemia or infarction, as evidenced by abnormalities of the ST segment or T wave in leads II, III, and aVF, should have right-sided leads V4R, V5R, and V6R obtained to assess for a possible right ventricular infarct. ST-elevation >1mm in lead V4R has sensitivity and specificity >90 percent for scintigraphic evidence of RV infarction, and approximately 80 percent for echocardiographic evidence of RV dysfunction. The right-sided ST elevation is often transient. The extent to which RVMI impacts the clinical presentation depends on its size and the relative degree of left ventricular dysfunction
The most reliable echocardiographic signs of hemodynamically important right ventricular infarction are:
§ Right ventricular cavity dilatation.
§ Impaired right ventricular free wall motion (hypokinesis, akinesis, or dyskinesis). The extent of right ventricular wall motion abnormality can vary from affecting only a small region adjacent to the inferior septum and left ventricular inferior segment to affecting a large portion of the right ventricular free wall. Patients with RVMI and hemodynamic compromise are likely to have wall motion abnormalities in a high percent of the right ventricle.
§ Diastolic reversed inter-ventricular septal curvature, systolic paradoxic septal motion or bulging of the inter-atrial septum towards the left atrium.
§ Decreased tricuspid annular plane systolic excursion (TAPSE) and/or reduced right ventricular ejection fraction.
§ Plethora of the inferior vena cava.
§ Impairment of tissue Doppler measures of right ventricular systolic function.
Cardiac magnetic resonance imaging (CMR) is considered the standard imaging technique for detailed evaluation of right ventricular structure and function. Contrast-enhanced cardiovascular magnetic resonance is more sensitive for the detection of right ventricular involvement than physical examination, electrocardiography, and echocardiography in patients with an inferior MI. In addition MRI evidence of substantial RV injury (substantial mass of the RV manifesting microvascular obstruction and/or delayed contrast enhancement) may predict adverse outcome. Tsang et al. report a patient with inferior myocardial infarction and failed revascularization found to have two large thrombi in the right ventricle on cine-magnetic resonance imaging that had not been detected by transthoracic echocardiography. They were later seen with contrast echocardiography5.
1. Stowers SA, Leiboff RH, Wasserman AG, Katz RJ, Bren GB, Hsu I. Right ventricular thrombus formation in association with acute myocardial infarction: diagnosis by 2-dimensional echocardiography. Am J Cardiol 1983; 52(October (7)): 912–3.
2. Chapoutot L, Nazeyrollas P, Metz D, et al. Floating right heart thrombi and pulmonary embolism: diagnosis, outcome and therapeutic management. Cardiology 1996; 87:169–74.
3. Cabin HS, Clubb KS, Wackers FJ, Zaret BL. Right ventricular myocardial infarction with anterior wall left ventricular infarction: an autopsy study. Am Heart J 1987; 113:16 – 23.
4. Boukantar et al. Right ventricular thrombus and pulmonary embolism in patient with anterior myocardial infarction European heart journal 2010; p. 2870
5. Benjamin K.T. Tsang, David G. Platts, George Javorsky, Martin Brown: Right Ventricular Thrombus Detection and Multimodality Imaging Using Contrast Echocardiography and Cardiac Magnetic Resonance Imaging. Heart, Lung and Circulation. 2012; 21:185–188