Effects of nifedipine on systemic and pulmonary vascular impedance in subjects undergoing cardiac catheterization.

Nifedipine 10 mg, administered sublingually to 12 patients following diagnostic cardiac catheterization, caused reduction in systemic resistance, and change of impedance together with alteration in contour of the ascending aortic and left ventricular pressure waves. The substantial reduction in ascending aortic and left ventricular systolic pressure with nifedipine occurred despite an increase in stroke volume and cardiac output, and was associated with similar reductions in mean pressure and indices of wave reflection. In the same patients, there were no significant changes in pulmonary vascular resistance or impedance, nor in pulmonary artery or right ventricular pressure pulse contour. For the systemic circulation, as with nitroglycerin and nitroprusside, reduction in wave reflection appears to be an important factor in the drug's action and for its beneficial effects on cardiac load in the treatment of angina pectoris, systemic hypertension and left ventricular failure. Thus the observed effects of nifedipine were attributed to vasodilatation of the systemic arteries and arterioles.