A 15-year-old asymptomatic, physically active man, who had a history of syncope at the age of 12 and a family history of arrhythmogenic right ventricular dysplasia (father), presented for evaluation. Physical examination revealed no abnormal findings. The ECG demonstrated sinus rhythm, Ϫ20°QRS, incomplete right bundle-branch block, and left ventricular hypertrophy; the 24-hour Holter monitoring excluded ventricular arrhythmias. Normal exercise capacity (15 metabolic equivalent) without arrhythmias was confirmed by treadmill exercise testing. The echocardiogram showed apical hypertrophy of the left ventricle and an interatrial pseudo-aneurysm without shunt ( Figure 1). To rule out right ventricular dysplasia, an ECG-gated cardiac MRI was performed. Surprisingly, the "black-blood" cardiac MRI examination demonstrated thickened apical segments of the myocardium and areas suspicious for deep intertrabecular recesses that were not observed at echocardiography (Figure 2). The diagnosis of isolated left ventricular noncompaction was confirmed through the use of a high-resolution cine gradient echo sequence that is particularly sensitive to slow flow (Figure 3). The presence of deep recesses filled with blood and trabeculations of the myocardium were evident during diastole, whereas during systole, the recesses collapsed and the myocardium appeared compacted. The right ventricle was normal.Noncompaction of the ventricular myocardium is a rare congenital cardiomyopathy characterized by an altered structure of the myocardial wall resulting from intrauterine arrest in normal endomyocardial embryogenesis and compaction of the myocardial fibers in absence of any coexisting congenital lesions. The morpho-pathological findings consist of multiple, prominent myocardial trabeculations and deep intertrabecular recesses communicating with the left ventricular cavity. The clinical manifestations are not specific for this cardiomyopathy and include heart failure, tachyarrhythmias (which predispose to sudden death), and cardioembolic events.This case provides evidence of the potential of cardiac MR imaging in the evaluation of the right ventricle and of cardiac anomalies such as noncompaction.

Inversion of the normal interatrial septum convexity has been described in patients with right atrial pressure or volume overload, but there is no reference to this abnormality in acute myocardial infarction. A group of 576 consecutive patients with acute infarction and serial echocardiographic studies were prospectively evaluated during a mean follow-up period of 406 days. Inverted interatrial septum convexity was found in 30 patients (5.2%); 29 of the 30 presented with inferior infarction with right ventricular involvement (29 [24.4%] of 119) and the remaining presented with cardiac tamponade secondary to heart rupture. The incidence of inverted interatrial septum convexity rapidly decreased, and after 3 months it was present in only five patients. All patients with inverted interatrial septum convexity had a right atrial pressure greater than or equal to pulmonary capillary pressure, a relation found in only 2 of 43 patients with right ventricular involvement and normal septal convexity. In patients with right ventricular infarction, right atrial pressure was higher in the presence of inverted septal convexity (15.9 +/- 4.1 versus 10.5 +/- 4.1 mm Hg, p less than 0.0001) and the incidence of hypotension (10 [34.4%] of 29 versus 15 [17.4%] of 90, p = 0.04) and third degree atrioventricular block (10 [34.4%] of 29 versus 11 [12.2%] of 90, p = 0.006) as well as the mortality rate after 3 months (9 [31%] of 29 versus 11 [12.2%] of 90, p = 0.04) were higher in the presence of inverted convexity than in patients with normal septal convexity.(ABSTRACT TRUNCATED AT 250 WORDS)

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