A Simple System to Deliver Blood Cardioplegia Sylvio C. Provenzano, Jr, MD, MS, Robert Stacey, CCP, David C. Newman, FRACS, MBBS, Hugh Wolfenden, FRACS, MBBS, Con Manganas, FRACS, MBBS, and Peter W. Grant, FRACS, MBBS Department of Cardiothoracic Surgery, Sydney Children’s Hospital, and Departments of Clinical Perfusion and Cardiothoracic Surgery, Prince of Wales Hospital, Sydney, New South Wales, Australia
We describe a simple and inexpensive system designed to deliver blood cardioplegia either diluted or at the patient’s hematocrit, with controlled temperature and additive concentration. This system can be applied to any pump set, and suits any strategy for clinical myocardial preservation. (Ann Thorac Surg 2005;80:1946 –7) © 2005 by The Society of Thoracic Surgeons FEATURE ARTICLES
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mproved myocardial protection is one of the reasons for the tremendous progress in cardiac surgery during the last 3 decades. Blood cardioplegia is the most common form of clinical myocardial preservation in the United States, according to the STS database [1]. The purpose of this report is to present a simple, economic, and reliable way of applying this technique, which has been in use at our institution for the past 25 years. This system was designed to deliver blood cardioplegia either diluted or at the patient’s hematocrit. Temperature control can be suited to cold, tepid, or warm cardioplegia delivery. Furthermore, it also allows addition of different substrates at known concentration, dispensing with the purchase of expensive brand cardioplegia solutions and extra devices.
Technique The system consists of a circuit utilizing an empty 1-liter Plasma-lyte solution bag (Baxter Health Care, Old Toongabbie, NSW, Australia), tubing connections with a coil for heat exchange (CardioResearch, Castle Hill, NSW, Australia), and a roller pump (Fig 1). Most of the tubing is 3/16 inches thick polyvinylchloride. The coil is a 3/16 inches thick polyurethane pipe, disposed in 20 loops. It fits into two stainless steel containers for heat exchange: one containing ice and the other containing water, which is thermostatically controlled and heated with heater elements. So, to cool or heat the blood cardioplegia, the coil is simply moved from one container to another. Silicone replacement tubing is used in the roller pump. The 1-liter Plasma-lyte solution plastic bag is used as Accepted for publication May 4, 2004. Address correspondence to Dr Grant, Department of Cardiothoracic Surgery, Prince of Wales Hospital, Barker St, Randwick 2031, Sydney, Australia; e-mail:
[email protected].
© 2005 by The Society of Thoracic Surgeons Published by Elsevier Inc
the cardioplegia reservoir. The total prime volume of the cardioplegia circuit is 300 mL, allocated as 200 mL in the bag and 100 mL in the tubing. The excess 700 mL of solution is directed to the oxygenator, constituting the prime. Once cardiopulmonary bypass (CPB) is stabilized and the patient’s temperature is 28°C, blood is derived from the arterial (aortic) line by removing clamp B and applying clamp A (see Fig 1). When the volume in the cardioplegia reservoir reaches 900 mL, clamp B is reapplied to isolate the cardioplegia from the main circuit. Substrates are added through the pressure port three-way tap, and the final cardioplegia solution is circulated to the desired temperature. Delivery is achieved by applying clamps B and C, and releasing clamp A (Fig 1). For a typical cardioplegia induction at our institution, we use the set described as above and a total volume of 900 mL at 10°C. The substrates used are potassium chloride (KCl) and sodium bicarbonate (Na HCO3). We add 20 mmol KCl to the cardioplegia blood; thus, its final concentration will be around 23 mEq/L. We also add 10 mmol Na HCO3 to keep pH around 7.45. For warm induction, cardioplegia is heated to 36°C, and the substrates are the same as for cold induction. Repeated doses are administered at 15- to 20-minute intervals, with 500 mL of pure pump blood at 10°C. If there is mechanical or electrical activity, 5 mmol KCl is added to the cardioplegia blood. Immediately before aortic unclamping, a last dose of warm (36°C) cardioplegia (“warm shot”) is administered (5 mmol KCl is added to 1 L blood). Cardioplegia delivery is based mainly on pressure: flow is adjusted to keep the cardioplegia line pressure of 150 mm Hg, which corresponds to approximately 80 mm Hg in the aortic root. For myocardial revascularization, we normally do the distal anastomoses first and the proximals with a side clamp. We use the Multiple Delivery Cardioplegia Set (Medtronic, Minneapolis, MN), which allows for vein grafts to be perfused either with cardioplegia (as soon as the distal anastomose is performed), or warm blood (when the aortic clamp is released). When retrograde cardioplegia is applied, the pressure is measured directly from the cannula, and kept between 30 mm Hg and 40 mm Hg, so that flow varies accordingly. The system configuration for pediatric cases is the same, but it differs in size: the tubing is 3/16 inches thick with a prime volume of 100 mL; the cardioplegia reser0003-4975/05/$30.00 doi:10.1016/j.athoracsur.2004.05.005
Ann Thorac Surg 2005;80:1946 –7
HOW TO DO IT PROVENZANO ET AL BLOOD CARDIOPLEGIA SYSTEM
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voir is a 500-mL Plasma-lyte solution plastic bag; and there is a one-way valve at the end of the cardioplegia line (just before connection to the cardioplegia cannula) to avoid air entering the system. The KCl concentration is the same as for adults. The cardioplegia doses for children less than 30 kg are 20 mL/kg and 10 mL/kg for induction and repeated doses, respectively.
Comment The concept and initial experience with blood cardioplegia were highlighted by the Buckberg group [2] in the late 1970s. The system described above was adapted by one of us (R.S.) 25 years ago and has been in use ever since in adult and pediatric cases, for any operation, regardless of complexity. From January 1996 to December 2003, 5,828 adults with median age of 67.75 years (range, 18 to 92) were operated on with the use of cardiopulmonary bypass (coronary artery disease or valve disease, or both, comprising 5,479 cases [94.1%], and others, 349 [5.9%]). Reoperations accounted for 9.1% (521) of the procedures. Overall mortality was 2.26% and the use of intraoperative and postoperative intraaortic balloon counterpulsation for lowoutput syndrome was 1.3%. Median cross-clamp and CPB times were 52 and 87 minutes, respectively. Seventysix percent of the hearts resumed spontaneous sinus rhythm after aortic cross-clamp removal. This cardioplegia circuit proved to be reliable, with good and reproducible results. It is quite simple to handle: it needs only one roller set from the main pump and two tubing clamps to operate. This system also suits any perfusion technique and surgical preference: the way of delivery can be antegrade or retrograde, including perfusion of vein grafts and coronary ostia; temperature
is easily set to warm, cold, or tepid. It allows continuous or intermittent delivery with controlled perfusion pressure. The cardioplegia hematocrit can be high (patient’s hematocrit) or low (diluted). In relation to cardioplegia additives, we solely use potassium chloride and sodium bicarbonate, but it is possible to add any other substrate such as magnesium sulfate, glutamate, aspartate, citrate, Tham, and so forth, with known concentrations. Regarding expenses, this system costs only 25% of other brand cardioplegia systems in our market (Au$ 50, against Au$ 200 for the most expensive; cardioplegia solution and additives not included). Total savings per year are significant, even in a moderately busy unit. If commercially available cardioplegia solutions or special perfusion pumps and their maintenance were to be included, the difference in cost would be even greater. In conclusion, this system to deliver blood cardioplegia is suitable for any clinical myocardial protection strategy. Moreover, it is cost effective, simple, and has proved to be reliable for more than 25 years.
The authors acknowledge the expertise of Mr Andrew Lahanas for editing the illustration and Mr Daminda Weerasinghe for data review.
References 1. STS U.S. cardiac surgery database. 1997 CAB only patients— univariate analysis: intraoperative variables. Available at: http://www.sts.org/doc/4722. Accessed March 31, 2003. 2. Follete DM, Mulder DG, Maloney JV, Buckberg GD. Advantages of blood cardioplegia over continuous coronary perfusion or intermittent ischemia: experimental and clinical study. J Thorac Cardiovasc Surg 1978;76:604 –19.
FEATURE ARTICLES
Fig 1. The system to deliver blood cardioplegia is depicted as recirculation mode. A, B, and C indicate where clamps are applied to operate the system. Arrows indicate flow direction.
