Absi, Tarek

Background Left ventricular aneurysm (LVA) is a significant complication of myocardial infarction that may lead to global left ventricular (LV) dysfunction. However, the exact mechanism underlying the abnormal function has not been elucidated. In this study we tested the hypothesis that changes in LV geometry cause both an increase in wall stress and a change in the temporal distribution of stress in the LVA border zone (BZ) during systole. Methods Transmural anteroapical infarcts were created in adult Dorsett sheep (n=8) and were allowed to mature into LVAs for 10 weeks. Animals were imaged subsequently using MRI with simultaneous recording of intraventricular pressures. Cardiac models were constructed from the MRI images at end-diastole, isovolumic systole, peak-systole and end-systole. Two short-axis slices, 1 basal and 1 apical were analyzed. The apical slice included the septal and anterior component of the aneurysm as well as the corresponding BZs and normal myocardium. Regional wall stresses were calculated using finite element analysis and compared with stresses in corresponding regions from normal control sheep (n=7). Results In the LVA group, stress was significantly increased in the BZ at the end-diastolic, isovolumic, peak-systolic, and end-systolic instants ( P <0.001 for all). In addition the temporal distribution of stress was significantly altered with maximum stress occurring at peak instead of isovolumic systole. Conclusions Geometric changes in the LVA hearts increased wall stress and altered its temporal distribution in the BZ region. Correlation of this finding with the corresponding regional blood flow, oxygen consumption, and mechanical systolic performance may help elucidate the mechanism underlying the observed global LV dysfunction.

The natural history of penetrating atherosclerotic ulcers (PAUs) of the descending thoracic aorta remains unclear. Between January 1996 and June 2000, PAU was diagnosed in 36 patients (16 men, 20 women; mean age 74.9 ± 1.5 years) at Washington University. Imaging studies and hospital records were reviewed. Late follow-up was by search of the Social Security Death Index and telephone interview. None of 16 asymptomatic patients underwent operation. At follow-up (median 457 days), 6 patients had died of unrelated and 2 of unknown causes. Among 20 symptomatic patients, 10 had associated intramural hematoma (5) or dissection (5), of whom 3 underwent operation. At median follow-up (448 days), the 7 unoperated patients remained alive without an aortic operation. Among the remaining 10 symptomatic patients, 3 had an aortic operation and 2 died of unknown causes during follow-up (median 586 days). These data suggest that, in selected cases, PAU may be managed expectantly with careful observation.