Hemodynamic effects of nitroglycerin.

The authors have studied the hemodynamic effects of sublingually administered nitroglycerin (NG). Obtained data indicate that the response to NG is time-dependent. A first phase, lasting about 2 minutes, is characterized by a reduction of total systemic resistance (TSR) and an increase of cardiac output (CO), without significant variations of left ventricular filling pressure (FP) and blood pressure (BP). A modest increase of heart rate (HR) is observed. The second phase is characterized by a reduced FP and later, after 5 minutes, of BP. Subsequently HR increases to a greater degree, CO decreases and TRS presents a variation toward control values.