Is Continuous Normothermic Blood Cardioplegia Really a Practical Way of Myocardial Preservation? Comparison with Intermittent Cold Crystalloid Cardioplegia

Summary

Commencing in September 1991, 30 consecutive patients who underwent coronary artery bypass grafting were operated on employing continuous normothermic blood cardioplegia (Group 1). 2.83 ± 0.81 distal anastomoses per patient were performed. The next 30 consecutive patients were operated on employing intermittent cold crystalloid cardioplegia (Group 2). 2.72 ± 0.95 distal anastomoses per patient were performed in this group. Cross clamping and cardiopulmonary bypass times were similar in both groups. Electromechanical activity beginning time (69.00 ± 94.04 sec. versus 101.50 ± 78.26 sec, p < 0.001) and QRS recovery time (10.92 ± 8.35 min.verus 19.60 ± 33.65 min., p < 0.05) were significantly shorter in Group 1 than in Group 2. Maximal potassium levels during cardiopulmonary bypass and in the postoperative period did not significantly differ between the groups. Postoperative serum CPKMB values were similar. Three patients in Group 1 and four in Group 2 needed IABP support in the early postoperative period. In Group 1, one and in Group 2 three patients suffered perioperative myocardial infarction (difference not significant). Postoperative cardiac index augmentation was significantly higher in Group 1 than in Group 2 (from 2.40 ± 0.57 L/min/m² to 3.04 ± 0.60 L/min/m² in Gr I, from 2.39 ± 0.64 L/min/m² to 2.86 ± 0.49 L/min/m² in Gr II, p < 0.01). Coronary sinus oxygen saturations during aortic cross-clamping were significantly higher in Group 1 (53.32 ± 12.18 % versus 17.82 ± 2.75 %, p < 0.001). There were no rhythm disturbances in Group 1 (0 %) but atrial fibrillation occurred in 5 (16.66 %) cases of the hypothermic group in the postoperative period. In Group 1, two patients, and in Group 2, three patients (difference is not significant) were lost in the early postoperative period.

We can say that continuous normothermic blood cardioplegia is a safe alternative way of myocardial protection with good clinical results despite its discomfortable and complicated delivery technique.

Zusammenfassung

Dreißig Koronarpatienten wurden mittels normothermer Blutkardioplegie (Gruppe I) und weitere 30 Patienten mittels kalter kristalloider Kardioplegie (Gruppe II) operiert. In Gruppe I wurden 300 ml/min einer normothermen Lösung von hochkonzentriertem Kalium und oxygeniertem Blut über 5 min antegrad appliziert und nach dem elektromechanischen Herzstillstand wurde dann eine entsprechende Lösung mit niedriger K-Konzentration in einer Dosis von 50 - 150 ml/min gegeben. In Gruppe II wurden anfangs ein Liter kalter kristalloider Lösung appliziert und später jeweils 100 ml via Venentransplantate. In Gruppe I betrug die Herztemperatur 35 - 37 °C, in Gruppe II 15 °C. Die Aortenabklemmzeit war mit rund 51 min in beiden Gruppen gleich. Die postoperativen CPK-MB-Werte waren in beiden Gruppen gleich. Der postoperative Schlagvolumenindex war in Gruppe I geringer als in Gruppe II, der Schlagvolumenindex des rechten Ventrikels war jedoch in Gruppe I höher, ebenso der Herzindex. In Gruppe II trat in 5 Fällen postoperatives Vorhofflimmern auf. Insgesamt betrachten die Autoren die normotherme Blutkardioplegie als eine sichere Methode der Myokardprotektion trotz der unbequemen und komplizierten Anwendungstechnik.

Key words

Cardioplegia - Normothermia - Hypothermia - Myocardial preservation