[Value of intravenous nitroglycerin in hypertension after extracorporeal circulation].

Abstract

The authors compare the haemodynamic effects of intravenous nitroglycerin (IV TNT) in 14 patients developing hypertension (mean blood pressure greater than 90 mmHg) and in seven normotensive patients (70 less than mean blood pressure less than 90 mmHg) after cardiac surgery with extracorporeal circulation (ECC). TNT was administered at doses of 0.5, 1, 2 microgram.kg-1.min-1 then 2 microgram.kg-1.min-1 with the association of vascular filling in order to restore right and left arterial pressures to their initial values. Various haemodynamic parameters were measured or calculated. The results obtained: in the hypertensive patients, at the low dose (0.5 microgram.kg-1.min-1) a prevalent venodilatory action was noted: RAP: 7.64 +/- 2.76 p less than 0.05; LAP: 9.07 +/- 3.19 p less than 0.05; at the middle dose (1 microgram.mg-1.min-1) venodilation continued resulting in a fall in BP 95.28 +/- 26.11 p less than 0.01 and above all in Cl: 2.28 +/- 0.36 p less than 0.01; at the maximum dose used, the action of TNT affected both the venous and arteriolar sector causing a major fall in BP: 89.64 +/- 23.88 p less than 0.001, in Cl: 2.29 +/- 0.33 p less than 0.01 and above all RVSI: 19.94 +/- 6.24 p less than 0.05. The association of vascular filling led to an increase in RAP and LAP (p = NS), Cl (p = NS) whilst BP remained low: 92.78 +/- 17.56 p less than 0.001 and also RVSI: 18.12 +/- 4.44 p less than 0.01. In the normotensive patients the administration of TNT, whatever the dose used, did not cause any significant changes (p = NS). In conclusion, the authors emphasise the value of the use of TNT in postoperative hypertensive states, in particular when associated with myocardial ischaemia.