Journal of cardiovascular pharmacology
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J. Cardiovasc. Pharmacol. · Nov 1999
Clinical TrialLeft ventricular chamber function during inhaled nitric oxide in patients with dilated cardiomyopathy.
Inhaled nitric oxide is a potent and selective pulmonary vasodilator. However, when used in patients with congestive cardiac failure, the decrease in pulmonary vascular resistance is associated with an increase in pulmonary capillary wedge pressure (PCWP). This study examined load-independent indexes of left ventricular chamber function during inhaled nitric oxide in 10 patients with dilated cardiomyopathy (mean ejection fraction, 30.2+/-7.8%, mean +/- SD). ⋯ Right heart filling pressures did not change. We therefore conclude that 20 ppm inhaled nitric oxide does not affect left ventricular chamber function in patients with controlled heart failure. Previously described elevations in PCWP during inhaled nitric oxide are most likely due to altered left ventricular loading conditions related to secondary pulmonary hypertension in severe heart failure.
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J. Cardiovasc. Pharmacol. · Nov 1999
Comparative StudyBeta-estradiol acutely potentiates the depression of cardiac excitability by lidocaine and bupivacaine.
Pregnancy is known to increase myocardial susceptibility to bupivacaine-induced cardiovascular collapse, and prolonged pretreatment of rabbits with high doses of progesterone potentiates bupivacaine's depression of the maximal rate of increase (Vmax) of the cardiac action potential. Short-term effects of progesterone are not detected in vitro, but other steroids elevated during pregnancy might be acutely active in this model. These experiments tested whether acute exposure to beta-estradiol potentiates local anesthetic/antiarrhythmic depression of Vmax and conduction velocity in rabbit cardiac tissue in vitro. ⋯ Nor is the potentiation due to a general decrease in membrane excitability because the comparable inhibition by TTX is insensitive to estradiol. Because beta-estradiol potentiates the inhibition of myocardial excitability, but alleviates the slowing of impulse conduction between the Purkinje fiber and ventricular muscle produced by local anesthetics, the hormone must produce changes in more than one ionic conductance. Both pregnancy and conditions that abnormally alter levels of steroid hormones have ramifications for local anesthetic-induced cardiotoxicity and antiarrhythmic pharmacotherapeutics.