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Detrimental effects of interrupting warm blood cardioplegia during coronary revascularization
H Matsuura1, H L Lazar, X M Yang
1Department of Cardiothoracic Surgery, Boston University Medical Center, Mass.
Insights
Interrupting warm blood cardioplegia during coronary revascularization increases myocardial damage. This method is less effective than continuous warm blood cardioplegia or cold blood cardioplegia, leading to greater ischemic injury.
Area of Science:
- Cardiovascular Surgery
- Cardiac Anesthesia
- Myocardial Protection
Background:
- Warm blood cardioplegia is an alternative to cold blood cardioplegia for myocardial protection.
- Continuous infusion in warm blood cardioplegia can obscure the surgical field, necessitating interruptions.
Purpose of the Study:
- To investigate the impact of interrupting warm blood cardioplegia on myocardial damage during coronary revascularization.
Main Methods:
- An experimental study in 30 adult pigs undergoing cardiopulmonary bypass and cardioplegic arrest.
- Three groups received different cardioplegia strategies: intermittent cold blood, continuous warm blood, and interrupted warm blood.
- Myocardial damage was assessed via tissue acidosis, echocardiographic wall-motion scores, and histological analysis of necrosis.
Main Results:
- Interrupting warm blood cardioplegia led to increased tissue acidosis compared to continuous warm or intermittent cold cardioplegia.
- Echocardiographic wall-motion scores were significantly worse in the interrupted warm blood group.
- Histological analysis revealed a greater area of necrosis in the interrupted warm blood cardioplegia group.
Conclusions:
- Interrupting warm blood cardioplegia during coronary revascularization compromises its protective effect.
- Interruption results in increased ischemic myocardial damage and should be avoided.
Abstract:
Warm blood cardioplegia has emerged as a substitute for cold blood cardioplegia as a method of myocardial protection. However, the continuous infusion of blood in this technique may obscure the operative field and necessitate interruption of warm blood cardioplegia. This experimental study was therefore undertaken to determine whether interrupting warm blood cardioplegia during coronary revascularization would increase myocardial damage. In 30 adult pigs, the second and third diagonal vessels were occluded with snares for 90 minutes. All animals underwent cardiopulmonary bypass and 45 minutes of cardioplegic arrest. During the period of cardioplegic arrest, 10 pigs received intermittent antegrade/retrograde infusion of cold blood cardioplegic solution (4 degrees C) 10 pigs received continuous retrograde infusion of warm blood cardioplegic solution (37 degrees C) at 100 ml/min, and 10 pigs received retrograde infusion of warm blood cardioplegic solution that was interrupted for three 7-minute periods. After aortic unclamping, the coronary snares were released and all hearts were reperfused for 180 minutes. Interrupting retrograde warm blood cardioplegia resulted in more tissue acidosis during cardioplegic arrest (6.20 +/- 0.16 interrupted retrograde warm blood cardioplegia and 6.45 +/- 0.12 continuous retrograde warm blood cardioplegia, both p < 0.05 compared with 6.98 +/- 0.17 intermittent antegrade and retrograde cold blood cardioplegia), decreased echocardiographic wall-motion scores (4 [normal] to -1 [dyskinesis]; 2.06 +/- 0.30 interrupted retrograde warm blood cardioplegia, p < 0.05 compared with 3.30 +/- 0.40 intermittent antegrade and retrograde cold blood cardioplegia, 2.80 +/- 0.40 continuous retrograde warm blood cardioplegia), and increased tissue necrosis as measured by the area of necrosis/area at risk (38% +/- 5% interrupted retrograde warm blood cardioplegia, p < 0.05 compared with 21% +/- 2% intermittent antegrade and retrograde cold blood cardioplegia; 25% +/- 2% continuous retrograde warm blood cardioplegia). We concluded that interrupting warm blood cardioplegia during coronary revascularization diminishes the effectiveness of warm blood cardioplegia and results in increased ischemic damage.