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MMCTS
(August 9, 2005). doi:10.1510/mmcts.2004.000711 Copyright © 2005 European Association for Cardio-thoracic Surgery Procedure Retrograde administrationDepartment of Cardiovascular Surgery, University Hospital Freiburg, Hugstetter Strasse 55, D-79106 Freiburg, Germany * Corresponding author: * Tel.: +49-761-270-2818; fax: +49-761-270-2550. E-mail: bothe{at}ch11.ukl.uni-freiburg.de
The use of retrograde cardioplegia is a safe, effective and widespread method for myocardial protection in a broad range of cardiac procedures. Retrograde cardioplegia may be delivered retrograde alone or, most frequently, in combination with an antegrade way of delivery. However, the degree of myocardial protection provided by retrograde cardioplegia may vary due to anatomic differences or for other reasons.
Key Words: Cardiac surgery • Myocardial protection • Retrograde cardioplegia
Retrograde cardioplegia (RCP) has gained wide acceptance as a method of myocardial protection in a broad range of cardiac procedures. RCP may be delivered retrograde alone or, most frequently, in combination with antegrade delivery. Table 1 illustrates the advantages provided by retrograde application of cardioplegia.
However, the efficacy and safety of using RCP alone for myocardial protection remains controversial. RCP has been shown to effectively cool the left ventricle. However, distribution of RCP to the free wall of the right ventricle may be poor because there is no direct communication between the coronary sinus (CS) and anterior cardiac veins. This may be problematic in patients with inadequate venous collaterals or right ventricular dysfunction if the RCP-catheter is placed too far to the left or if aortic occlusion time is expected to be long [1]. The degree of myocardial protection provided by retrograde cardioplegia may also vary for anatomic and other reasons (Table 2).
In addition, cardiac arrest achieved by retrograde administration of cardioplegia usually takes longer as compared to the arrest achieved by antegrade delivery. Different catheters for instituting retrograde cardioplegia can be used. Differences in catheters used for instituting retrograde cardioplegia are listed below:
We use a catheter with flexible stylet and self-inflating balloon (Photo 1).
A purse-string is placed in the anterior caudal right atrium prior to venous drainage catheter insertion. The catheter is introduced through the purse-string and atriotomy. The catheter should be held in the left hand and the tip introduced across the atrial wall. The right index finger is placed just medial to the right atriocaval junction, which is near the sinus orifice. The catheter tip is then directed towards the left atrial appendage as the right index finger deflects the catheter into the sinus orifice (Schematic 1 and Video 1).
After correct intubation, the catheter can be felt passing posteriorly along the atrioventricular groove in the CS. The catheter should be maintained within 3 cm of the orifice and the stylet carefully removed to avoid dislodgement. Retrograde catheter placement can be performed with or without cardiopulmonary bypass support (CPB). Some surgeons consider it easier to intubate the sinus before the venous return cannula has been placed and cardiopulmonary bypass begun. The retrograde catheter can then be placed with direct palpation of the CS via the venous cannula purse-string of the right atrial appendage. Dislodgement of the CS catheter is rare with the introduction of the venous return cannula. Another, even simpler method for retrograde catheter placement is direct CS cannulation via a small atriotomy in the mid-right atrial wall during CPB. This method may be preferred when a tricuspid valve operation is performed or other right atrial approaches are necessary. To prevent dislodgement of the CS catheter which is advanced not too far into the CS, it is sometimes helpful that the perfusionist starts delivery of the blood cardioplegic solution slowly. The first dose of blood-based cardioplegia (cold induction) should be given in antegrade and retrograde directions sequentially. RCP should be delivered with a pressure-limiting system to prevent damage to the CS and pressure should be maintained at less than 50 mmHg. Either intermittent or continuous infusions of RCP may be administered, with flow rates of 100–150 ml/min being optimal. We recommend venting of the aortic root during RCP. For the standard composition and application of blood cardioplegia please refer to the chapter on blood cardioplegia and Video 1 (doi:10.1510/mmcts.2004.000745).
RCP has become a safe, widespread and effective method for myocardial protection in addition to antegrade cardioplegia alone. RCP is especially recommended in certain cases such as redo CABG [2] or in patients with severe coronary artery disease involving the left main and right coronary arteries [3]. In redo CABG retrograde cardioplegia diminishes the likelihood of embolization via patent but atherosclerotic vein grafts by antegrade cardioplegia. A recent review showed failure to use RCP as the largest independent predictor of mortality in coronary reoperations [4]. We recommend the sole delivery of RCP in the case of significant aortic regurgitation or in acute aortic dissection Stanford type A. However, the efficacy and safety of using RCP alone for myocardial protection has certain limitations, especially regarding right ventricle protection [1]. Distribution of RCP to the right ventricle may be limited in patients with inadequate venous collaterals if the RCP-catheter is placed too far to the left or if aortic occlusion time is expected to be long. If possible, antegrade cardioplegia should then be given additionally, as antegrade cardioplegia is relatively well distributed to both ventricles in the absence of coronary artery disease. However, the final dose of cardioplegia should be given retrogradely in order to remove air from the coronary arteries. Our policy is to give blood-based cardioplegia in antegrade and retrograde directions sequentially. This procedure requires a pressure control to prevent rupture of the CS. We prefer to use antegrade and retrograde cardioplegia simultaneously in coronary bypass surgery. After completion of the first distal anastomosis, we apply blood cardioplegia via the grafts and CS simultaneously. This procedure allows higher flow rates due to less increase in pressure. However, there is evidence that a continuous way of RCP delivery may result in improved ventricular performance and reduces myocardial ischemia in comparison with intermittent administration in the case of prolonged aortic cross-clamping [5]. Also, venting of the aortic root during RCP may be discussed. Some surgeons consider venting unnecessary or even deleterious, as it may prevent deep penetration of cardioplegia [6]. Our group, however, routinely vents the aortic root to prevent distention of the left ventricle and to limit the amount of blood in the coronary arteries, especially for CABG. The retrograde catheter can be positioned several centimeters into the sinus or proximal to the first venous branch. We prefer placing it several centimeters into the sinus to prevent intraoperative dislodgement. In experienced hands, the use of RCP is associated very rarely with complications, such as perforation of the CS by the catheter tip during catheter insertion, ruptures of the CS during infusion of cardioplegia due to overpressurization of the CS or overinflation of the CS catheter balloon. Meticulous repair of an empty, well-protected and arrested heart is recommended in such cases to achieve secure hemostasis and CS patency. The CS defect can be directly closed with prolene sutures or, in more complicated cases, pericardial or vein patches can be used for closure. CS catheter-related injuries are frequently difficult to repair and potentially lethal due to inadequate myocardial protection, inadvertent coronary artery injuries and possibly post-repair CS thrombosis [7]. However, reports of complications are rare. RCP is a safe, widespread and effective method for myocardial protection in addition to antegrade cardioplegia alone.
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