[Sinus node inhibitors in coronary surgery]

Abstract

In patients with coronary artery disease, rapid ventricular rates require adequate treatment since disturbed oxygen balance and ischemia may be incurred. By virtue of their isolated action on the sinus node, "specific bradycardic substances" have only negligible hemodynamic side effects and, accordingly, represent an alternative to other available rate-slowing drugs. The clonidine derivative, alinidine (N-allyl-clonidine) was used primarily as the specific bradycardic substance in our studies in patients at the time of aortocoronary bypass surgery. In addition to its rate-slowing properties, this substance also elicits an analgetic and anti-ischemic effect and, in a small percentage, it is metabolized to clonidine. The purpose of this study was to assess the effectiveness and hemodynamic actions of alinidine in the treatment of intraoperative heart rate acceleration and, in combination with the calcium channel blocker nifedipine, to evaluate its use for postoperative hypertension. The first study was performed in nine patients in whom, during aortocoronary bypass surgery, there was a heart rate increase in excess of 20% above the preoperative control value. Patients were excluded with impaired ventricular function, absence of sinus rhythm, concomitant increase in arterial mean pressure greater than 30%, hypovolemia, pulmonary capillary wedge pressure in excess of 15 mmHg as well as those with ECG changes precluding exact assessment of myocardial ischemia. In addition to the ECG, the following parameters were registered: heart rate, arterial pressure, central venous pressure and, with a semi-floating balloon-tipped catheter, pulmonary artery pressure as well as pulmonary wedge pressure. Cardiac output was determined with thermodilution.(ABSTRACT TRUNCATED AT 250 WORDS)