Nitroprusside and Nitroglycerin in Acute Myocardial Infarction

Abstract

In 16 patients, within 24 h of the beginning of an acute myocardial infarction the hemodynamic effects of intravenous infusion of nitroglycerin (NTG) and nitroprusside (NP) were compared in the same patients (Table 1). To provide a common basis for comparison, the mean arterial pressure was lowered to the same level. Left ventricular filling pressure (LVFP) was decreased to the same extent. Cardiac index (CI) and stroke volume index (SVI) declined significantly during NTG and did not change during NP. The differences in CI and SVI during NTG- and NP-infusion were significant (p > 0.05). These data confirm results reported in the literature that NP has a relatively balanced effect on the arterial and venous circulation whereas NTG has less effect on systemic vascular resistance compared to its effect on capacitance vessels and LVFP accordingly [10]. Thus, NTG more likely decreased CI and SVI, occasionally to a critical level. During NP infusion, even with a fall in LVFP to a range of 5–10 mmHg, CI and SVI did not decline significantly and never to a critical point. Furthermore, the half-life of NP is short, and unintentional overtreatment with NP can quickly be reversed by stopping or slowing the infusion rate, whereas NTG has a somewhat longer-lasting effect. Thus, in the commonly encountered clinical situation NP is expected to have the more favorably balanced beneficial hemodynamic effects.