Biomedical subjects

B Shareef

Publications and source records attributed to B Shareef.

3 recordsLinked to original sources

PubMed1999

Functional assessment with electrocardiographic gated single-photon emission computed tomography improves the ability of technetium-99m sestamibi myocardial perfusion imaging to predict myocardial viability in patients undergoing revascularization.

This study evaluates the use of electrocardiographic (ECG) gated single-photon emission computed tomographic (SPECT) myocardial perfusion imaging for the prediction of viability in patients undergoing revascularization, who have coronary disease and left ventricular dysfunction. Fifty patients underwent technectium-99m (Tc-99m) sestamibi ECG gated SPECT imaging preoperatively at rest and 1 week after revascularization, whereas 36 (72%) also underwent imaging 6 weeks after revascularization. Images were interpreted by the consensus of 3 experienced readers without knowledge of patient identity or time of imaging (pre- or postrevascularization) for perfusion and wall motion using a 17-segment model. Results of perfusion alone were compared with perfusion and wall motion combined. One hundred five coronary artery territories were revascularized, 96 of which were viable and 9 nonviable. Perfusion alone predicted 87 to be viable and 18 nonviable (sensitivity 86%, specificity 55%, positive predictive value 95%, negative predictive value 28%, and overall accuracy 85%). Perfusion and wall motion combined identified 95 territories to be viable (sensitivity 95%; p <0.025; specificity 55%, positive predictive value 96%, negative predictive value 50%, and overall accuracy 91%; p <0.05). Thus, Tc-99m sestamibi ECG gated SPECT myocardial perfusion imaging at rest allows assessment of both perfusion and wall motion, which significantly improves the sensitivity and overall accuracy for determination of viability in comparison with perfusion alone.

Aged↗

PubMed1995

Serotonin and serotonin antagonism in cardiovascular and non-cardiovascular disease.

Serotonin, or 5-hydroxytryptamine, is a naturally-occurring vasoactive substance found primarily in the brain, enterochromaffin tissue, and blood platelets. It has diffuse cardiophysiologic effects. The multiple effects of serotonin on blood vessels can be explained by the existence of 2 serotonergic receptor subtypes (the S1 receptor mediates vasodilation, and the S2 receptor vasoconstriction). Serotonin via the S2 receptor also augments the actions of several other vasoconstricting substances. Serotonin may be responsible for causing, or at least perpetuating, some forms of systemic hypertension through peripheral and central nervous system (CNS) actions. Ketanserin is a highly selective S2-serotonergic antagonist with additional alpha-adrenergic blocking activity, which has been proposed as a therapy for various cardiovascular diseases including hypertension. It has been shown to be more effective than placebo in treating hypertension and comparable in effectiveness to other antihypertensive drugs. Its major side effects relate to the CNS, and prolongation of the electrocardiogram QT interval has been described. Caution must be used when using ketanserin in patients receiving potassium- and magnesium-losing agents, because of the risk of torsades de pointes. Ketanserin has potential utility in the treatment of eclampsia, peripheral vascular disease, carcinoid syndrome, and "shock lung." The drug is not yet approved for clinical use in the United States.

Animals↗

PubMed1994

Relation between myocardial infarct location and stroke.

OBJECTIVES: We sought to compare the likelihood of stroke in patients with anterior versus nonanterior myocardial infarction. BACKGROUND: The association between anterior infarction and left ventricular thrombus has led to the assumption that embolization from thrombi is an important cause of stroke in patients with anterior infarction. We hypothesized that if anterior infarction is a cause of left ventricular thrombi, the number of strokes should be disproportionately higher in patients with anterior than nonanterior infarction. METHODS: We performed a retrospective analysis of 2,466 patients randomized from day 3 to day 15 after infarction as part of a multicenter placebo-controlled study of diltiazem to prevent cardiac death or myocardial infarction. Any acute focal cerebral disorder resulting in localizing findings characterized as a stroke or transient ischemic attack was considered an event. RESULTS: Of 91 events during a follow-up period of 12 to 52 months, 23 (3.2%) occurred in 724 patients with an anterior and 68 (3.9%) in 1,742 patients with a nonanterior myocardial infarction (relative risk 0.81; 95% confidence interval 0.51 to 1.30). Power analysis revealed that the negativity of the study was not the result of inadequate sample size. Life table analysis showed no difference in cumulative event rate (p = 0.42) according to site of infarction. Cox regression analysis showed that of 10 clinical covariates, only systolic blood pressure was predictive of stroke (p < 0.001). The use of warfarin did not contribute to the model. Finally, the addition of site of infarction (anterior vs. nonanterior) did not contribute significantly to the Cox model. CONCLUSIONS: Although there is a significant incidence of stroke after acute myocardial infarction, there is no relation between the occurrence of stroke and site of infarction. These data do not support the presumed causal relation between anterior myocardial infarction, thrombus and stroke.

Adult↗