Carvedilol Improves Myocardial Contractility Compared With Metoprolol in Patients With Chronic Hibernating Myocardium After Revascularization

Synthesis and biological evaluation of [131I]iodocarvedilol as a potential radiopharmaceutical for heart imaging

The optimization of the radiolabeling yield of carvedilol with iodine-131 was described. Dependence of the labeling yield of [¹³¹I]iodocarvedilol on the concentration of carvedilol, chloramine-T content, pH of the reaction mixture and reaction time was studied in details. Carvedilol was labeled with iodine-131 at pH 6 with a labeling yield of 92.6 ± 2.77% by using 100 µg carvedilol, 200 µg chloramin-T (CAT) and 30 min reaction time. The formed [¹³¹I]iodocarvedilol was nearly stable for a time up to one day. Biodistribution of [¹³¹I]iodocarvedilol was investigated in experimental animals. [^131/123I]iodocarvedilol was located in the heart with a concentration of 19.6 ± 0.41% of the injected dose at 60 min post injection. It has a high heart uptake and heart to liver ratio, both of which are beneficial for high-quality SPECT (single-photon emission computerized tomography) myocardial imaging. [^131/123I]iodocarvedilol solve most the drawbacks of the FDA (Food and Drug Administration) approved ^99mTc-sestamibi.

Clinical Review: Is the Perioperative Use of β-Blockers Still Recommended? A Critical Review of Recent Controversies

The optimal role of β-adrenergic receptor blockade in the perioperative period remains unclear in patients at risk for cardiovascular events. Cardiovascular complications continue to be the most common cause of perioperative morbidity and mortality, and cardioprotective properties of β-blockers are widely recognized, yet the results of the clinical trials investigating the use of different β-blockers in the perioperative period are controversial. The discrepancy might be related to differences in the design of studies, use of different agents, administration by different routes, and continuation for different time intervals. Evidently, perioperative mortality and morbidity seem to be related to heart rate, and the majority of complications are related to β-blockers’ side effects. Based on the observations from different studies, we propose an algorithm for perioperative β blockade.

Application of zinc-bis-(DL-hydrogensaspartate) does not reduce apoptotic cell death in myocardial infarction in the rat heart

BACKGROUND

Early studies in different stress models have shown potential beneficial effects of exogenous zinc application with reduction in the rate of apoptotic cell death. This has not been shown in models of myocardial infarction.

METHODS

Rats were exposed to either brief episodes of acute ischemia followed by reperfusion (phase 1) or chronic coronary occlusion (phase 2). Animals were either treated with zinc or vehicle. Groups 1 and 3 received zinc-bis-(DL-hydrogenaspartate) 10 mg/kg body weight as a single 5-mL bolus administered intraperitoneally 24 hours prior to coronary occlusion, groups 2 and 4 received saline. The infarct sizes were determined by triphenyltetrazolium chloride staining and expressed at relative areas to areas of ischemia. Histological slices of the rat's myocardium at the border zones of the infarcts were stained with the TUNEL method to assess for apoptosis. Animals in groups 5, 7, and 9 received zinc, given once before and then repeated every 4 days after coronary occlusion, whereas groups 6, 8, and 10 received saline. Animals were observed for observation periods of 13 (groups 9 and 10), 16 (groups 7 and 8), or 19 weeks (groups 5 and 6), respectively. Two-dimensional echocardiography was performed to measure ejection fraction (EF) at baseline and at the end of the observation periods. TUNEL staining was used to detect and quantify apoptosis rate in the border zones of infarcts after the hearts were excised.

RESULTS

Infarct sizes were 49% + 22% in group 1 (zinc + 30 minutes ischemia + 30 minutes reperfusion); 48% + 10% in group 2 (vehicle + 30 minutes ischemia + 30 minutes reperfusion); 42% + 11% in group 3 (zinc + 60 minutes ischemia + 30 minutes reperfusion); and 41% + 23% in group 4 (vehicle + 60 minutes ischemia + 60 minutes reperfusion). In group 1, 11% + 6% of cells were apoptotic compared to 12% + 4% in group 2, 16% + 9% in group 3, and 17% + 7% in group 4 (P > .05). In phase 2, echocardiography revealed a significant reduction in EF in all groups after coronary occlusion. There were no significant differences in EF between the 5 groups at baseline and at follow-up. TUNEL staining did not reveal any significant apoptosis after 13 to 19 weeks.

CONCLUSION

Application of zinc failed to result in reduction of infarct size after temporary coronary occlusion followed by reperfusion and did not demonstrate any reduction in apoptotic cell death. In chronic coronary occlusion, zinc also did not improve EF compared to controls in the presented model in rats. The mechanisms involved in antiapoptotic effects seem to be more complex and might not be inducible by simple zinc injections.