"Initial, continuous and intermittent bolus" administration of minimally-diluted blood cardioplegia supplemented with potassium and magnesium for hypertrophied hearts.

BACKGROUND: Hypertrophied hearts are subject to the deleterious effects of intraoperative ischemia-reperfusion, and stable maintenance of myocardial cardioplegic arrest is essential. Continuous cardioplegia infusion appears an ideal modification to overcome this issue, except for a large amount of crystalloid solution infused into the myocardium. We previously introduced "initial, continuous and intermittent bolus" administration of minimally-diluted blood cardioplegia (mini-BCP) supplemented with potassium and magnesium, and this study was designed to elucidate its efficacy in patients with hypertrophied hearts. METHODS: Thirty patients (M:F=17:13, 69.2+/-7.8 years) with left ventricular mass index greater than 150 g/m(2) who underwent aortic valve replacement between 1996 and 2002 were enrolled, and were allocated to one of the two groups. The same infusion protocol was used for both groups as follows: initial and intermittent (every 20 min) BCP was antegradely infused for 2 min at the rate of 200 mL/min, and continuous retrograde BCP flow rate was set at 60-100mL/min. Group C (n=15) received 4:1-diluted BCP modified with Buckberg solution, and Group M (n=15) were given mini-BCP supplemented with potassium (initial/others: 15.4/9.8 mEq/L) and magnesium (initial/others: 6.5/4.0 mEq/L). RESULTS: Stable cardioplegic arrest was maintained in all study patients, and total amount of crystalloid solution as cardioplegia was lesser in Group M (79.4+/-27.5 mL) than in Group C (937.3+/-372. 1mL, p<0.01). Group M showed a higher incidence of spontaneous heartbeat recovery after aortic unclamping (13 versus 6, p<0.05) and a lower incidence of postoperative atrial fibrillation (0 versus 5, p<0.05). Postoperatively, maximum dopamine dose (3.35+/-2.27 microg/kg/min versus 5.49+/-2.30 microg/kg/min, p<0.05) and peak plasma creatine kinase-myocardial band (CK-MB) (21.7+/-7.2 IU/L versus 28.8+/-8.4 IU/L, p<0.05) were lower in Group M. Early postoperative echocardiography revealed a lower incidence of paradoxical ventricular septal motion (M versus C; 3 versus 10, p<0.05) and greater left ventricular ejection fraction (M versus C; 70.7+/-4.0% versus 67.0+/-5.3%, p<0.05) in Group M. CONCLUSIONS: These results suggest that "initial, continuous and intermittent bolus" administration of mini-BCP, supplemented with potassium and magnesium, is a novel modification for patients with hypertrophied hearts in terms of simplifying the maintenance of cardioplegic arrest with beneficial myocardial protective effects.

Minimally-diluted blood cardioplegia supplemented with potassium and magnesium for combination of 'initial, continuous and intermittent bolus' administration.

BACKGROUND: The present study was designed to examine the hypothesis that minimally-diluted blood cardioplegia (BCP) supplemented with potassium and magnesium provides superior myocardial protection in comparison with the standard-diluted BCP for a combination of 'initial, continuous, and intermittent bolus' BCP administration. METHODS AND RESULTS: Seventy patients undergoing elective coronary revascularization between 1997 and 2001 (M : F =55:15, mean age 67.6+/-7.5 years) were randomly divided into 2 groups: Group C (n=35) was given the standard 4:1-diluted blood-crystalloid BCP, and Group M (n=35) was given minimally-diluted BCP supplemented with potassium-chloride and magnesium-sulfate. The BCP temperature was maintained at 30 degrees C. Cardioplegic arrest was induced with 2 min of initial antegrade BCP infusion, followed by continuous retrograde BCP infusion. Intermittent antegrade BCP was infused every 30 min for 2 min. The time required for achieving cardioplegic arrest was significantly shorter in Group M (47.5+/-16.3 vs 62.5+/-17.6 s, p<0.0001). The number of patients showing spontaneous heart beat recovery after reperfusion was significantly larger in Group M (28 vs 15, p=0.0029), and the number of patients suffering from atrial fibrillation during the postoperative period was significantly smaller in Group M (n=3 vs 11, p=0.034). Both the postoperative maximum dopamine dose (3.57+/-2.46 vs 5.44+/-2.23 microg/kg per min, p=0.0014) and peak creatine kinase-MB (19.5+/-8.5 vs 25.8+/-11.9 IU/L, p=0.0128) were significantly less in Group M. The number of patients showing paradoxical movement of the ventricular septum in the early postoperative echocardiography was significantly smaller in Group M (9 vs 24, p=0.0007). CONCLUSIONS: These results suggest that 'initial, continuous and intermittent bolus' administration of minimally-diluted BCP supplemented with potassium and magnesium is a reliable and effective technique for intraoperative myocardial protection.