Recent animal studies suggest that cardiac hypertrophy compromises the coronary circulation. Although flow per gram of ventricle in most animal models of hypertrophy is normal, coronary vasodilator responses to pharmacological or physiological stimuli are mildly impaired. Studies of regional perfusion indicate that the limitation of coronary vasodilator capacity in hypertrophied ventricles primarily affects the endocardium. In contrast to studies in animals, measurements of coronary reactive hyperemia in man suggest that coronary dilator responses are profoundly depressed in patients with severe left ventricular hypertrophy secondary to aortic stenosis. These studies in man demonstrate that alterations in the coronary circulation secondary to cardiac hypertrophy are of sufficient magnitude to contribute to the development of angina and heart failure (secondary to endocardial fibrosis) in patients with aortic stenosis.

Animals↗

PubMedDate not supplied

Revascularization of myocardial infarction complicated by cardiogenic shock: an update. Abstracts & commentary.

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Journal Article↗

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Peripheral vascular effects of a new dopamine analog: 5-6-dihydroxy-2-methylaminotetralin (M-8).

It has been reported that the cyclic dopamine analog 5,6-dihydroxy-2-methylaminotetralin (M-8) in an adrenergic agonist in the dog. In this study, the effects of M-8 on hindlimb vascular responses was determined in the dog. In group I (n = 10), hindlimb vascular responses to ipsilateral femoral artery injections of M-8 before and after adrenergic blockade were determined. Mean femoral artery and peripheral venous pressures and heart rate responses to intra-arterial injections of M-8 were recorded. Mean femoral artery flows were measured by an electromagnetic flowmeter. Low doses of M-8 (0.0001-01 micrograms/kg) elicited transient dilatory responses, while higher doses (1-10 micrograms/kg) produced a biphasic response consisting of a dilation followed by constriction. The dilatory responses were attenuated following pretreatment with propranolol and were augmented by pretreatment with phenoxybenzamine. The constrictor responses were attenuated by pretreatment with phenoxybenzamine. The constrictor responses were attenuated by pretreatment with pehnoxybenzamine and augmented by pretreatment with propranolol. These responses were not reflex-mediated, since the hemodynamic parameters in the contralateral limb were not altered during the depressor or pressor phases. In group II (n = 5), the effects of intra-arterially infused M-8 (0.01 micrograms/kg/min) on plethysmographically determined hindlimb venous capacitance were determined. Intra-arterial infusion increased venous capacitance through beta-adrenergic mechanisms without altering mean arterial pressure and heart rate or contralateral limb mean femoral artery flows. M-8 is a potent peripherally acting adrenergic agent.

Animals↗

PubMedDate not supplied

Evaluation of cerebrovascular Doppler examination and oculopneumoplethysmography in a clinical perspective.

The cerebrovascular Doppler examination (CDE) and oculopneumoplethysmography (OPG-Gee) were compared in a single population group with no statistically significant difference found between the 2 studies. There appeared to be an advantage to combinant testing, for when the results of the 2 studies were concordant there was an accuracy of 94% and a false negative rate of 8%. Clinical correlation was available in 96% of the patients, providing adequate evidence to support the adjuvant role of non-invasive screening in the evaluation of symptomatic individuals. The percentage of false negative studies and the incidence of ulcerative disease make a diagnostic role impractical at present. For the asymptomatic individual, the diagnostic role of non-invasive screening seems justified. The false negative studies in the present series were confined to those vessels with 50-70% stenoses, which are difficult to assess angiographically and may be better characterized by hemodynamic evaluations.

Cerebral Angiography↗