Retinal fluorescein angiography: A sensitive and specific tool to predict coronary slow flow

Background

Obstructive coronary artery disease (OCAD) and coronary slow flow (CSF) are frequent angiographic findings for patients that have chest pain and require frequent hospital admission. The retina provides a window for detecting changes in microvasculature relating to the development of cardiovascular diseases such as arterial hypertension or coronary heart disease.

Changes in blood-flow distribution during acute emotional stress in dogs

Summary The changes in mesenteric, renal and hindlimb circulations during natural emotional stress have been investigated in dogs. Arterial pressure showed a moderate and generally byphasic rise. Heart rate rose markedly in most experiments, but tended to return towards control values more rapidly than blood pressure. Both mesenteric and renal vascular resistance were increased. In the kidney, however, the vasoconstriction was less constant and in most instances less pronounced than in splanchnic viscera. This suggested a relatively high threshold of the central neuron pools controlling the renal vessels. Also, the reduction of blood flow was less sustained in the renal than in meseteric vessels, probably because of the action of autoregulatory mechanisms in the kidney. In hindlimb skeletal muscles, emotional stress produced a vasodilatation which appeared to be independent of the blood pressure rise and, at least to a large extent, of muscle activity. Most likely, the effect was due to sympathetic vasodilator fiber activation, though there was some indication that vasoconstrictor fibers to skeletal muscles were also activated. The observation that muscle vasodilatation invariably occurred in response to very different emotional stimuli suggests that it is a component of most, if not all, emotional reaction patterns in dogs. Muscle vasodilatation was the primary vascular reaction to changes from resting condition to alertness, the mesenteric and renal vessels being only slightly constricted or unaffected.Supported by a grant from the Consiglio Nazionale delle Ricerche, Roma.     

Beta adrenergic receptor activity in peripheral vascular beds of the unanesthetized dog

Summary The effects of blockade and stimulation of beta adrenergic receptors on mesenteric, renal and hindlimb circulations have been investigated in unanesthetized resting dogs. Propranolol and isoproterenol have been used for beta blockade and stimulation, respectively. The changes in oxygen consumption in the hindlimb following beta receptor stimulation have also been studied in some experiments performed under anesthesia.Beta receptor blockade was followed by an increase in vascular resistance which was very slight in the kidney, quite marked in the mesenteric bed and still greater in the hindlimb. This effect was accompanied by moderate bradycardia and moderate arterial hypertension.Beta receptor stimulation caused, besides tachycardia and hypotension, a drop in vascular resistance in mesenteric and hindlimb circulations. In the latter, the effect was greater, it peaked considerably later and was paralleled by an increase in local oxygen consumption.The data suggest that beta adrenergic receptors mediate a tonic vasodilator influence on the mesenteric and skeletal muscle circulations, in which these receptors abound. The different magnitude and pattern of the vasodilator effect of iso-proterenol in these circulations seem more consistent with a different local metabolic response than with an uneven density of beta receptors. The tonic vasodilator action is practically nil in the kidney, where beta receptors appear to be sparse or absent.Supported by a grant from the Consiglio Nazionale delle Ricerche, Roma