RESUMEN
Opioids are widely used as analgesics to supplement general anaesthesia or as adjunct to anaesthetic agents and for long term analgesia and sedation in intensive care patients. Some clinical studies have suggested that opioids may have different and deleterious haemodynamic effects that remain incompletely examined. We compared the direct cardiac effects of fentanyl and remifentanil in isolated Wistar rat hearts. Twenty rats were randomly assigned to two groups. Hearts were perfused with modified Krebs Henseleit solution and were exposed to 1x10-6moles(M)/L fentanyl (n=10) in Group I and 1x10-6 M/L remifentanil (n=10) in Group II. Heart rates, contractile force and coronary perfusion were recorded continuously during the study. There was a significant decrease in heart rate and increase in contractility and coronary perfusion in two groups (p<0.001). Fentanyl had less depressant effects on heart rate than remifentanil. We conclude that in isolated rat heart, fentanyl and remifentanil cause direct negative chronotropic and positive inotropic effect. Remifentanil had more depressant effects on heart rate than fentanyl in isolated rat heart.