A nonpeptide angiotensin II type 2 receptor agonist does not attenuate postmyocardial infarction left ventricular remodeling in mice.

Cardiac overexpression of the angiotensin II type 2 receptor (AT2 R) attenuates left ventricular (LV) remodeling after myocardial infarction (MI) in transgenic mice. We hypothesized that a novel nonpeptide AT2 R agonist, compound 21 (C21), would attenuate post-MI LV remodeling. Fifty-nine mice were studied for 28 days after 1-hour surgical occlusion-reperfusion of the left anterior descending coronary artery. Immediately thereafter, 23 mice received 0.3 mg·kg·d of C21 via Alzet osmotic minipump, 16 received 10 mg·kg·d of the AT1 R antagonist candesartan in drinking water, and 20 were untreated controls. Cardiac magnetic resonance imaging measured ejection fraction (EF), LV end-systolic, and end-diastolic volumes (ESVI and EDVI) indexed to weight serially post MI. Infarct size was measured on day 1 by late gadolinium-enhanced cardiac magnetic resonance imaging. At baseline, heart rate, blood pressure, EDVI, ESVI, and EF were similar between groups. Mean infarct size (42%-45% of LV mass) was similar between groups. C21-treated animals demonstrated adverse LV remodeling (increased EDVI and ESVI at all post-MI time points) compared with control. Candesartan therapy preserved left ventricular EF at day 28 compared with the C21-treated group. Thus, direct stimulation of the AT2 R by C21 at 0.3 mg·kg·d does not attenuate post-MI LV remodeling in reperfused MI in mice.

Pre-procedural planning for percutaneous atrial septal defect closure: transesophageal echocardiography compared with cardiac computed tomographic angiography.

BACKGROUND: The safety and efficacy of percutaneous closure of atrial septal defects (ASDs) is determined by several variables, including defect size, presence of adequate rim tissue, relationship to other cardiac structures, and associated congenital anomalies. OBJECTIVE: We sought to determine the accuracy of computed tomographic angiography (CTA) in predicting a defect's size compared with pre-procedural transesophageal echocardiography (TEE) and to the current "gold standard" balloon sizing by intracardiac echocardiography (ICE). METHODS: Thirty-five consecutive patients referred for possible percutaneous closure of suspected secundum ASD were evaluated with gated multislice CTA after initial TEE screening. Axial and sagittal image planes of the ASD from the CTA multiplanar reformation (MPR) images were used to measure the defect size and surface area. RESULTS: Of the 35 patients with secundum-type ASDs, 5 subjects had disqualifying anatomy by CTA and 2 had an unsuccessful closure, resulting in a procedural success rate of 93%. Measurement of defect area by gated MPR images provided the strongest correlate to ICE balloon size. In large ASDs, TEE was less well correlated to the maximum defect size and identification of the inferior/inferoposterior rims than CTA. CONCLUSIONS: Cardiac CTA is an accurate and useful technique for pre-procedural assessment of ASDs and may be superior to conventional TEE in large defects that have deficient inferior rims.