Right Ventricular False Aneurysm After Unrecognized Myocardial Infarction 28 Years Previously
A 74-year-old woman underwent an abdominal computed tomography scan for work-up of unclear recurring abdominal discomfort because abdominal ultrasound had not been diagnostic on account of a poor acoustic window and obesity (body mass index 31). Computed tomography did not detect any abdominal pathology but revealed an unclear mass located at a left anterior position on the cranial side of the diaphragm, most likely related to the apical portions of the heart (Figure 1). Thus, the patient was referred to our hospital for further cardiological work-up.
Interestingly, the patient had been hospitalized twice at intervals of 4 months because of 2 episodes of severe chest pain 28 years previously, but no diagnosis could be made at that time. Routine ECG on admission revealed an abnormal electrical axis as well as high R-wave amplitudes in V2 and V3 (Figure 2). Consequently, additional right ventricular leads were obtained, demonstrating discrete ST-segment elevations (rV1 to rV4) and negative T waves (rV2 to rV6) (Figure 3), indicating possible right ventricular pathology. Because transthoracic echocardiography could not reveal any right ventricular abnormality (Figure 4 and online-only Data Supplement), the patient was referred to cardiovascular magnetic resonance (CMR) imaging (1.5 Tesla “Sonata”, Siemens Medical Systems, Erlangen, Germany).
Cine images were acquired using fast gradient echo steady-state free precession sequences demonstrating normal global left and right ventricular function (left ventricular ejection fraction 64%, end-diastolic volume 100 mL, right ventricular ejection fraction 67%, and right ventricular end-diastolic volume 99 mL). However, the mass previously seen on computed tomography was also present on CMR images (37×27 mm), originating from the apical region of the right ventricle (Figure 5 and online-only Data Supplement). Time-resolved gadolinium contrast bolus tracking revealed contrast passage from the right ventricle into the mass (Figure 6 and online-only Data Supplement), which was connected directly to the right ventricular cavity by a thin mouth (5 mm in diameter). Ten minutes after injection of 0.2 mmol/kg gadodiamide, contrast images were obtained using an inversion recovery gradient echo technique (inversion-recovery fast low-angle shot), constantly adjusting inversion time to null normal myocardium. Contrast images showed late gadolinium enhancement in large portions of the mass (Figure 5). Thus, the diagnosis of apical right ventricular aneurysm was made.
Invasive angiography revealed only minor coronary plaque formation without significant stenosis. However, 1 prominent plaque located in the dominant left circumflex artery supplying the infero-apical myocardium might have been the culprit lesion for an apical right ventricular myocardial infarction, explaining the occurrence of the aneurysm as well as the 2 episodes of severe chest pain 28 years previously (Figure 7 and online-only Data Supplement).
For further patient management it is important to differentiate false from true ventricular aneurysm because false aneurysms have a significantly higher propensity for potentially fatal rupture,1 even in the chronic state. Thus, pathoanatomic hallmarks for differentiation of false from true aneurysm, so far only described from left ventricular necropsy studies,2 were applied in this case to the right ventricle on the basis of CMR findings.3 Because the aneurysm mouth was small (5 mm) and the ratio of its internal orifice width to the diameter of the aneurysm cavity was 0.1 (cut off <1.0), the mass was ruled to be a false aneurysm and the patient was referred to surgery. Importantly, CMR was used in this case because echocardiography was not diagnostic on account of poor acoustics and the infero-apical location of the aneurysm.
Surgical aneurysm resection was followed by histopathological work-up comprising trichrome staining for delineation of general histological characteristics, as well as desmin immunostaining for detection of myocardial fibers, which is the gold-standard for histological differentiation of false from true aneurysm.2 On the basis of histopathology, the noninvasive diagnosis of false right ventricular aneurysm was confirmed (Figure 8).
Aneurysms of the right ventricle are extremely rare, and only a few cases have so far been described.4 To our knowledge, this is the first report demonstrating the noninvasive in vivo diagnosis of a right ventricular false aneurysm applying left ventricular post mortem criteria in accordance with subsequent histopathological confirmation.
The online-only Data Supplement is available with this article at http://circ.ahajournals.org/cgi/content/full/118/20/2111/DC1.