Pheochromocytoma and myocardial infarction.

Pheochromocytomas are rare chromaffin cell tumors, 90% of which arise from the adrenal glands. Pheochromocytomas presenting with true myocardial infarction are even more rare. We report a 76-year-old man who had a previously undiagnosed pheochromocytoma, and presented with the uncommon complication of myocardial infarction.

Activation of ATP-sensitive potassium channels contributes to reactive hyperemia in humans.

Activation of ATP-sensitive potassium (KATP) channels present on vascular smooth muscle cells causes membrane hyperpolarization and vasodilation. The purpose of this study was to determine whether KATP channels contribute to reactive hyperemia in humans. Accordingly, we studied the effect of tolbutamide, a KATP channel inhibitor, on reactive hyperemic forearm blood flow.

Endothelial release of nitric oxide contributes to the vasodilator effect of adenosine in humans.

Background: The endogenous nucleoside adenosine plays an important role in the regulation of vascular tone, especially during ischemia. Experimental data derived from animal models suggest that nitric oxide (NO) contributes to the vasodilator effect of adenosine. The primary purpose of this investigation was to determine whether the endothelial release of NO contributes to adenosine-induced vasodilation in humans.

Myogenic and agonist induced responses of coronary venules after cold hyperkalaemic cardioplegia.

Objective: The aim was to examine agonist induced and myogenic venular responses after crystalloid cardioplegia in conditions simulating cardiopulmonary bypass.

Methods: Hearts of pigs were arrested with cold hyperkalaemic ([K+] = 25 mM) crystalloid cardioplegic solution for 1 h under conditions of cardiopulmonary bypass. In another group, hearts were arrested and then reperfused with warm blood for 1 h while being separated from cardiopulmonary bypass.

Coronary microvascular responses after exposure to iodinated contrast media.

Rationale And Objectives: Iodinated contrast media can cause a number of well-described acute hemodynamic and vascular effects including vascular spasm, hypotension, and arrhythmias. Coronary microvessels were studied in vitro after high-dose exposure to an ionic, high-osmolar contrast agent diatrizoate meglumine in vivo. The aim of this study was to examine the endothelium-dependent and endothelium-independent vasodilator responses of the microvessels after previous contrast media administration in a clinically relevant setting.

Blood and albumin cardioplegia preserve endothelium-dependent microvascular responses.

Alterations of vascular reactivity may be a cause of reduced myocardial perfusion after cardioplegic arrest. The effects of blood and albumin cardioplegia on endothelium-dependent coronary microvascular function and ultrastructure were examined after cardiopulmonary bypass, ischemic arrest, and reperfusion. During cardiopulmonary bypass, porcine hearts were arrested with either blood, albumin-crystalloid, or crystalloid cardioplegia for 1 hour, followed with reperfusion for 1 hour.

Relaxation responses of the coronary microcirculation after cardiopulmonary bypass and ischemic arrest with cardioplegia: implications for the treatment of postoperative coronary spasm.

Coronary arteriolar spasm may occur following cardiopulmonary bypass and ischemic arrest, resulting in impaired cardiac function. Because myocardial perfusion is principally regulated by the microcirculation, the in vitro effects of various clinically used vasodilating drugs on porcine coronary microvessels less than 200 microns in diameter were examined following cardioplegic arrest and reperfusion. After 1 hour of ischemic arrest using either crystalloid or blood cardioplegia solutions followed by 1 hour of reperfusion, microvessels were studied in a pressurized (40 mmHg), no-flow state, and imaged with a video tracking device.

The effect of norepinephrine on the coronary microcirculation.

The role of the sympathetic nervous system in the regulation of large coronary artery tone has been well defined. Studies of adrenergic regulation of coronary-resistance vessels have largely been limited to indirect inferences based on flow measurement obtained in vivo. The purpose of the present study was to determine the effects of norepinephrine (NE) on the coronary microcirculation using direct in vitro approaches.

Role of the endothelium in modulation of the acetylcholine vasoconstrictor response in porcine coronary microvessels.

Study Objective: The aim was to investigate the role of the endothelium in modulating the acetylcholine response in porcine coronary microvessels and compare the results with simultaneously studied large coronary arteries.

Design: Coronary microvessels [104 (SEM 3.3) microns; range 38-150] were removed from fresh porcine hearts and studied in vitro during no flow constant pressure conditions.

Characteristics of canine coronary resistance arteries: importance of endothelium.

Canine coronary resistance vessels were studied in vitro to examine the role of the endothelium in modulating responses to acetylcholine, vasopressin, and thrombin and to compare these responses to those found in large epicardial vessels. Acetylcholine had no effect on passively distended microvessels; however, after preconstriction with the thromboxane analogue, U 46619 caused dose-dependent vasodilation [50% effective concentration (EC50), 0.05 microM; maximum response, 97.

Isolated dissecting aneurysm of the renal artery.

A 40-year-old man with a history of renal stone formation was evaluated for left flank pain. An excretory urogram failed to show any renal calculi. However, renal arteriography and computerized tomography studies demonstrated a primary dissection of the left renal artery with resulting decreased perfusion to the lower pole of the left kidney.