T delivery to the myocardium through the coronary

Transcription

1 Facile Retrograde Cardioplegia: Transatrial Cannulation of the Coronary Sinus Steven R. Gundry, MD, Alexandro Sequiera, MD, Anees M. Razzouk, MD, Joseph S. McLaughlin, MD, and Leonard L. Bailey, MD Divisions of Cardiothoracic Surgery, Departments of Surgery, Loma Linda University Medical Center, Lorna Linda, California, and University of Maryland Hospital, Baltimore, Maryland The benefits of coronary sinus (CS) cardioplegia are well known, yet CS cardioplegia is not used widely owing to the need for bicaval cannulation, snares, and an atriotomy. We designed and used in 225 consecutive patients a catheter containing a flexible removable stylet that, when shaped into a hockey-stick configuration, enabled blind intubation of the CS through a small pursestring in the right atrium, guided easily into the CS using a finger on the atrioventricular groove at the inferior vena cava. The CS was intubated in all patients; a pressure-limited balloon at the catheter tip was inflated after crossclamping. An integral distal pressure line measured CS pressure. Catheters were placed distally within the great cardiac vein beyond the posterior interventricular vein; the position did not alter cooling: right ventricular free wall, septum, and left ventricular free wall temperatures were 7" * 2", 8" & 2", and 7" 2 2"C, respectively, after an initial 10 ml/kg of blood cardioplegia. Transatrial CS cardioplegia was used in 45 aortic valve replacements, 22 mitral valve replacements, 4 triple-valve replacements, 6 congenital lesions, and 148 coronary revascularizations, including 40 redo operations. Atheromatous material was routinely flushed retrogradely from cut old vein grafts during revascularization; 70 revascularizations (47%) were performed urgently for acute infarction or jeopardized myocardium. No heart block or CS injury occurred, and inotrope use dropped to 10% of patients (from 38% in the previous 256 patients with antegrade blood cardioplegia). We conclude that the CS can be cannulated transatrially and that CS cardioplegia is more facile than antegrade cardioplegia. Transatrial CS cardioplegia appears to be the cardioplegic method of choice. (Ann Thorac Surg ) he concept of providing nutrient flow or cardioplegic T delivery to the myocardium through the coronary veins is not new [l-61. Indeed, Lillehei and associates [7] successfully treated calcific aortic stenosis by means of a pump oxygenator and retrograde coronary sinus perfusion as early as The techniques of retrograde coronary sinus perfusion or cardioplegia delivery have changed little since that time. Heretofore, it has been necessary to provide two caval cannulas, snares around each cava during bypass, and an atriotomy and visual localization of the coronary sinus to deliver retrograde cardioplegia. Thus, despite any real or perceived advantages that retrograde cardioplegia might have over antegrade cardioplegia in terms of myocardial protection, difficulty in administering retrograde cardioplegia precludes its widespread use. Beginning in February 1988, we began applying our laboratory-derived concept of transatrial cannulation of the coronary sinus [8, 91 to our clinical practice in an effort to make retrograde cardioplegia as facile as antegrade cardioplegia. This report details the first 225 patients treated with transatrial coronary sinus cardioplegia (TACSC). Presented at the Thirty-sixth Annual Meeting of the Southern Thoracic Surgical Association, Scottsdale, AZ, Nov 9-1 1, Address reprint requests to Dr Gundry, Department of Surgery, Lorna Linda University Medical Center, Lorna Linda, CA Material and Methods Put ien ts All patients receiving cardioplegic arrest on the service of the primary author (S.R.G.) from February 1988 to January 1989 at the University of Maryland Hospital, Baltimore, MD, and from February 1989 to May 1989 at Loma Linda University Medical Center, Loma Linda, CA, had transatrial cannulation of the coronary sinus as the sole form of cardioplegia delivery. Additionally, from March 1988 to May 1989, patients undergoing initially aortic valve replacement and progressing to redo coronary artery bypass operations and patients undergoing high-risk or emergent coronary artery bypass operations at the University of Maryland Hospital had TACSC as the sole method of cardioplegia delivery. In all, a total of 225 patients ranging in age from 2 years to 89 years were treated with TACSC. Operations performed included 45 aortic valve replacements, 6 combined with coronary bypass, and 22 mitral valve replacements or repairs, 8 combined with coronary bypass; 6 of these operations were combined aortic and mitral valve procedures. Four patients underwent triple-valve repair and/or replacement. Six congenital lesions consisting of atrial or ventricular septa1 defects were treated. There were 148 coronary artery revascularizations, of which 40 were reoperations. Seventy patients were operated on emergently (within 6 hours of diagnosis) or urgently (within by The Society of Thoracic Surgeons /90/$3.50

2 Ann Thorac Surg CUNDRY ET AL 883 Fig 1. Assistant s-side insertion of G u n d y RCSP catheter through pursestring high in right atrium. Catheter is shaped in hockey-stick configuration or gentle curve and passed into great cardiac vein, beyond the posterior interventricular vein. Note surgeon s left hand on diaphragmatic surface of the heart with index and long fingers at junction of inferior vena cava and atrioventricular groove, to guide catheter into coronary sinus. hours) for unstable angina or acute infarction. On the primary author s service, where technically feasible, at least one internal mammary artery was used in the revascularizations. Technique Cannulation sutures are routinely placed in the aorta, atrium, and/or cavae for appropriate arterial and venous cannulation. An additional pursestring is placed just inferior to the junction of the right atrial appendage and right atrium (Figs 1, 2) for TACSC. After adequate heparinization, the aorta is cannulated for arterial inflow. A 180-cm (6-ft) arterial pressure line is passed over the ether screen to the anesthesiologist, who connects it to the pulmonary artery pressure transducer and flushes it with heparinized saline solution. This line will subsequently be connected to the distal pressure line incorporated into the TACSC catheter. Fig 2. Surgeon s-side insertion of Gundry RCSP cathether through pursestring high in right atrium. Note insert showing balloon inflated to seal coronary vein during cardioplegia delivery. Balloon remains inflated until cross-clamp is removed. Distal pressure lumen is connected to transducer above ether screen.

3 884 GUNDRY ET AL Ann Thorac Surg The Gundry RCSP catheter (DLP, Inc, Grand Rapids, MI) with its flexible stylet is shaped into a hockey-stick configuration with a gentle curve on its end (see Figs 1,2). If patient stability permits, a stab wound is placed inside the TACSC pursestring, the RCSP catheter is placed into the right atrium, and the snare is gently snugged. The catheter can be introduced from either the operator s or first assistant s side of the table. We and others have fouod that when first learning the technique, insertion from the assistant s side is inherently easier (see Fig l), and it is explained first. The catheter is held in the right hand, and the left hand index and long fingers are placed on the diaphragmatic surface of the heart at the junction of the inferior vena cava and atrioventricular groove. The tip of the catheter is located with these fingers by feeling through the atrial wall. A gently pushing motion with the right hand is used to guide the tip of the catheter into the coronary sinus and advance it beyond the posterior interventricular vein upward toward the left shoulder. The catheter s advancement is confirmed by palpation with the fingers of the left hand. Intubation from the surgeon s side is somewhat more difficult at first, as the angles used for both hands limit motion. The catheter is grasped with the left hand while the right hand is placed along the diaphragmatic surface of the heart (see Fig 2). Either the index and long fingers or the little and fourth fingers at the inferior vena cava and atrioventricular groove junction are used to locate the catheter tip transatrially and guide it into the coronary sinus and into the great cardiac vein. From the surgeon s side, the cannula is more likely to either enter the right ventricle or get caught in the posterior interventricular vein but these are easily recognized and corrected. Confirmation of placement is obtained by manually palpating the catheter in the atrioventricular groove posteriorly. If not felt, it is most likely in the right ventricle. We have not seen arrhythmias once the catheter is in the great cardiac vein. Arrhythmias usually imply that the catheter is within the right ventricle. Further confirmation of placement is done by withdrawing the stylet and observing black pulsatile blood in the cannula. The cannula is secured by snaring down the snugger and securing with a free tie around the movable ring on the cannula. The previously flushed 180-cm (6-ft) pressure line is connected to the clear pressure port on the RCSP cannula and a coronary sinus waveform tracing is observed on the monitor. Once in place, venous cannulas are inserted per the surgeon s preference. eemarkably, there have been no catheter dislodgements by the venous cannulas. Bypass is commenced in standard fashion. If patient instability warrants placement on bypass before insertion of the RCSP cannula, the cannula can be placed during bypass. Usually, it is easier to intubate the coronary sinus by passing the RCSP cannula over the venous cannula, but accasionally intubation is only possible behind and under the venous cannula. Administration of Cardioplegia In this series, all patients were cooled to a core temperature of 26 to 28 C. A cardiac insulator pad was placed behind the heart. Cold blood cardioplegia was used as the only cardioplegia in all patients. During cooling, the blood cardioplegia line from the perfusionists was flushed and connected to the central RCSP catheter port. A 3-mL syringe was attached to the blue balloon port. Initially, a left ventricular vent was placed through the right superior pulmonary vein in all patients, but in the last 100 patients, only an aortic needle vent has been used for revascularizations. When the patient was systemically cool, or when fibrillation occurred, iced saline solution or Ringer s lactate slush was applied to the heart, an aortic cross-clamp applied, and retrograde cardioplegia started at a flow of 100 ml/min. Three milliliters of air was put into the balloon of the RCSP catheter and the anterior heart inspected. The veins were noted to be full and red and the arteries blue! Initial suction on the aortic needle vent also revealed blue, deoxygenated blood. Simultaneously, the coronary sinus pressure was observed on the monitor. The pressure usually rose to 30 to 50 mm Hg as the perfusionist increased flow to 250 to 300 ml/min. If the pressure did not rise, either the balloon would be inflated further, or the catheter had dislodged. We have used up to 5 ml of air without problems. Cardiac arrest usually occurred within 20 to 30 seconds. Occasionally, fine fibrillation was seen in the most superior aspect of the right ventricular outflow tract. This ceased quickly. A total dose of 10 ml/kg was given as an initial bolus. Repeat 5-mL/kg doses were given every 30 minutes or whenever myocardial temperatures exceeded 20 C. All distal vein graft anastomoses were completed first. Redo operations were performed by cutting old patent grafts in half before starting retrograde cardioplegia. In most cases, proximal anastomoses were performed during rewarming, using a partial occluding aortic clamp. Once the aortic cross-clamp was released, the balloon on the RCSP catheter was deflated, but the catheter was left in place until all anastomoses were complete. Results The coronary sinus was intubated in all cases. There were 6 cases Qf catheter dislodgement, all but 1 case occurring during a single week when perfusionists used up to 500 ml/min flow through the catheter, causing a garden hose effect. All catheters were easily replaced by reinserting the stylet. There was no coronary sinus or cardiac vein damage or disruption. There was no evidence of atrioventricular groove hemorrhage or myocardial hemorrhage. Coronary sinus pressures never exceeded 60 mm Hg, although when manipulating the heart, the pressure monitoring port could be compressed intermittently, simulating higher pressures. Myocardial temperatures were recorded in the right ventricular free wall, septum, and left ventricular free wall

4 Ann Thorac Surg 1990:50:882-7 GUNDRY ET AL 885 in the first 100 patients. Temperatures after the initial dose of 10 mukg of cardioplegia were as follows: right ventricle, 7" f 2 C; septum, 8"? 2 C; left ventricle, 7" f 2 C. No temperature differences were found between patients with patent or acutely occluded arteries. Due to this uniformity of cooling, temperature monitoring is not a routine part of our current practice. Inotropes were used in 23 of 225 patients, usually low doses (2 to 5 pg. kg-'. min-') of dopamine or dobutamine. This compares with 97 of 256 (38%) patients receiving antegrade blood cardioplegia in the same practice during 1987 [lo]. There were two deaths at Loma Linda, one occurring in a balloon pumpdependent patient with an ejection fraction of less than 0.20 arriving in shock, the second occurring in a bedridden 79-year-old woman who survived a redo double-valve replacement and triple coronary artery bypass but died of hospitalacquired pneumonia 2 weeks postoperatively. Intraoperative echocardiography of prebypass and postbypass function was obtained using transesophageal probes in valve and valve/revascularization procedures. All 40 patients studied had preserved or improved right ventricular function before chest closure. Comment Retrograde cardioplegic protection of the myocardium has entered a period of rapidly increasing interest by researchers and clinicians. Its appeal stems from the known limitations of antegrade delivery of cardioplegia, namely, inadequate distribution of cardioplegia distal to coronary artery lesions [ll], damage to coronary ostia, difficulty in ostial cannulation, and distal emboli frotn previous vein grafts. In contrast, retrograde cardioplegia provides uniform distribution of cooling throughout both ventricles [8, 91 despite coronary lesions (Table 1). Coronary ostia are neither sought nor injured with retrograde methods. Old vein grafts can be cut and any distal embolic material flushed retrogradely out of the coronary arteries and old grafts. Moreover, reoperations with patent internal mammary arteries are possible as all parts of the heart receive adequate myocardial protection. Mitral and aortic valve operations are accomplished more expeditiously; the operation can proceed without the interruption of cannulating coronary arteries or putting retractors down to restore aortic valve competence before more antegrade cardioplegia. Finally, myocardial protection in acute aortic dissection is equally enhanced. Despite these obvious benefits, the principal limitation of retrograde cardioplegia has heretofore been the complicated steps required to cannulate the coronary sinus, ie, bicaval cannulation, caval snares, and an atriotomy. Not only are these time consuming, but valuable crossclamp time can be expended while searching for and then cannulating the coronary sinus through a small atriotomy. These drawbacks notwithstanding, Menaschh and associates [12] have reported on 500 consecutive aortic valve replacements using retrograde coronary sinus cardioplegia with results at least equal to those of antegrade cardioplegia. Table 1. Observed Benefits of Transatrial Corona y Sinus Retrograde Cardioplegia Operation Aortic valve replacement Mitral valve replacement Coronary revascularization Redo revascularization IMA = internal mammary artery Benefits No searching for coronary ostia Exploration and excision of aortic valve while giving dose Working on valve while giving initial and repeat cardioplegia Flushing calcific debris from coronary ostia Final dose can "clean" coronary arteries and root Exploration and retraction of atrium while giving initial dose Continuing the operation in the atrium while giving subsequent doses Even cooling of entire heart Elevation of the heart and dissection of coronary arteries while giving cardioplegia Protection of myocardium in areas destined for IMA graft(s) Cooling protection of myocardium distal to acute occlusions Prevention of distal vein graft atheromatous emboli Flushing atheromatous emboli out of coronary arteries Protection and cooling of heart with intact IMA grafts It is our belief that retrograde cardioplegia must be as facile to administer as antegrade cardioplegia for it to become more widely used. To that end, we have now demonstrated that the coronary sinus can be easily consecutively intubated transatrially by a variety of surgeons and used with good results on a variety of Cardiac lesions. In doing so, we have become convinced that in certain lesions, transatrial coronary sinus cardioplegia is more facile than antegrade cardioplegia. These lesions include all valve replacements, valve and coronary combination operations, redo operations, and revascularizations for acute myocardial ischemia. With practice, intubating the coronary sinus is as easy as putting a cardioplegia needle into the ascending aorta.

5 886 GUNDRY ET AL Ann Thorac Surg We have further demonstrated that good clinical results can be obtained without combining retrograde with prior doses of antegrade cardioplegia. This "antegrade retrograde" method unnecessarily complicates a simple procedure. Moreover, this practice may prove harmful if valuable time is lost searching for coronary ostia, if coronary ostia are damaged, or if vein graft atheromatous material is flushed down into coronary arteries antegradely. Two additional findings require comment. First, we have used pressures as great as to 60 mm Hg within the coronary sinus without damage. Indeed, research on the beating, working heart with an arterialized, occluded coronary sinus found that pressures as great as 60 mm Hg could be tolerated without hemorrhage or edema [13]. By decompressing the nonworking heart, as in this study, high pressures may be tolerated even further. Finally, a key to facile retrograde cardioplegia is the placement of the balloon and catheter well into the great cardiac vein, usually past the posterior interventricular vein. Experimental results of such placement have previously confirmed the excellent cooling of the entire heart by this method [8, 91. Clinical temperature data in this report further support the more distal placement of the catheter to avoid dislodgement during cardiac manipulation. Based on our experience with 225 patients, we conclude that the coronary sinus can be easily intubated transatrially using a catheter with a flexible stylet. The use of surgeon-controlled balloon inflation and distal pressure monitoring have ensured adequate delivery of cardioplegia without coronary sinus or myocardial injury. Transatrial coronary sinus cardioplegia may be the cardioplegia method of choice for all operations, but at the very least it offers a superb alternative method of cardioplegia delivery for valve operations, aortic root reconstructions, revascularizations, and acute myocardial ischemia. References 1. Roberts JT, Browne RS, Roberts G. Nourishment of the myocardium by way of the coronary veins. Fed Proc 1943;2: Blanco G, Adam A, Fernandez N. A direct experimental approach to the aortic valve, acute retroperfusion of the coronary sinus. J Thorac Surg 1955;32: Davies AL, Hammond GL, Austen WG. Direct left coronary artery surgery employing retrograde perfusion of the coronary sinus. J Thorac Cardiovasc Surg 1967;54: Lolley DM, Hewitt RL, Drapanas T. Retroperfusion of the heart with a solution of glucose, insulin and potassium during anoxic arrest. J Thorac Cardiovasc Surg 1974;63: Menasche P, Kural S, Fauchet M, Lavergne A. Retrograde coronary sinus perfusion: a safe alternative for ensuring cardioplegic delivery in aortic valve surgery. Ann Thorac Surg 1982;34: Solorzano J, Taitelbaum G, Chiu RC-J. Retrograde coronary sinus perfusion for myocardial protection during cardiopulmonary bypass. Ann Thorac Surg 1978;25: Lillehei CW, Deverall RA, Gott VL, Varco RL. A direct vision correction of calcific aortic stenosis by means of a pump oxygenator and retrograde coronary sinus perfusion. Dis Chest 1956;30: Gundry SR, Kirsh MM. A comparison of retrograde cardioplegia versus antegrade cardioplegia in the presence of coronary artery obstruction. Ann Thorac Surg 1984;38: Gundry SR, Kirsh MM, Long RW. Right atrial, coronary sinus, or aortic root cardioplegia: comparison of delivery techniques in the presence of coronary artery obstructions. Chest 1984;86:313. Gundry SR, Sequier A, Coughlin TR, McLaughlin JS. Postoperative conduction disturbances: a comparison of blood and crystalloid cardioplegia. Ann Thorac Surg 1989; Fisk RL, Ghaswalla D, Guilbeau EJ. Asymmetrical myocardial hypothermia during hypothermic cardioplegia. Ann Thorac Surg 1981;34: Menasche P, Subayi J-8, Piwnica A. Retrograde coronary sinus cardioplegia for aortic valve operations: a clinical report on 500 patients. Ann Thorac Surg 1990;49:55M. Hammond GL, Davies AL, Austen WG. Retrograde coronary sinus perfusion: a method of myocardial protection in the dog with left coronary artery occlusion. Ann Surg 1967;166: DISCUSSION DR RICHARD E. CLARK (Bethesda, MD): I have had the privilege of hearing some of Dr Gundry's work before when he was a visitor at the National Institutes of Health. I think this work is important. I have a couple of questions for you with regard to it. Why have you abandoned use of stopping the heart immediately with an antegrade dose to give you additional time to put in the retrograde? Second, you noted that there was a difference in inotrope use and you have disclaimed any efficacy there. For your patient population, particularly in those undergoing redo operations, have you found any difference in mortality, which you carefully avoided mentioning? DR JOSEPH M. CRAVER (Atlanta, GA): I just have two technical questions. One relates to the particular benefit of retrograde cardioplegia in those patients who have chronic total occlusion of the proximal right coronary artery in protecting the right ventricle. In this circumstance antegrade cardioplegia administration may leave this area, which is also subject to surface warming, unprotected and in jeopardy of further dysfunction. With regard to that, how do you prevent an insertion of the catheter too deeply into the coronary sinus whereby the retrograde flow may not perfuse the inferior vein and the other right-sided structures? Second, how do you carefully administer the amount of fluid into the balloon of the catheter to avoid any local trauma to the area of the coronary sinus where the balloon might be located? DR KIT V. AROM (Minneapolis, MN): I have one brief question. I may have misunderstood. Do you run cardioplegia for 300 ml/min continuously? DR GUNDRY: Thank you very much for those very pertinent remarks. First of all, one of the reasons we chose to do this study is to perhaps demonstrate to ourselves and to a large number of people that there is no need, at least in our hands, for any

6 Ann Thorac Surg GUNDRY ET AL 887 combination of antegrade and retrograde delivery of cardioplegia. We believe that the initial use of antegrade cardioplegia just complicates an extremely simple technique, and have always been taught that the simpler, the better. Antegrade cardioplegia would not be efficacious in those patients who have aortic insufficiency, and particularly in redo operations where our main fear is delivering atheromatous material down vein grafts. The antegrade cardioplegia is not needed in our hands. We get immediate cessation of function in the heart using retrograde cardioplegia, and I believe many reports about retrograde cardioplegia being very slow to stop the heart have been a result of a fear of, in a beating heart, going above the magic pressure of 60 mm Hg. I may just say that the coronary veins have no capillaries, so that when you blow up the coronary sinus balloon you, in a sense, have a capillary wedge pressure effect. And if the ventricle is not completely decompressed, you will actually view the left ventricular pressure through the coronary veins. The coronary veins during systole are frequently exposed to left ventricular pressure, and as long as you have egress of blood through some vent somewhere, you can exceed this pressure. So we have not found any need for antegrade cardioplegia. If people want to use that, that is just fine. There are plenty of systems on the market. I just feel it is a little too complex. In regard to our mortality statistics, there were a total of six deaths in this group. All of those deaths except one occurred in patients on intraaortic balloon pumps directly from the catheterization laboratory, two of them subsequently needing left and right ventricular assist device support. Surprisingly, the rest of the patients undergoing emergent revascularization emerged from the operating room usually not requiring any inotropes, which, again, has been a pleasant surprise to all of us using this technique. With regard to the question about putting the cannula too far, I believe this is an unfortunate misconception that has been perpetrated through the years. Because of the dense venous network and venous arterial connections within the heart, you do not have to worry about the right ventricular posterior branches with your coronary sinus cannula. We have always put this cannula beyond the posterior interventricular veins so that it will not come out, and we are delighted see our cardioplegia moving through these veins, even using the veins as an egress of the heart. And as you can see from our temperature mapping, the right ventricle is extremely well cooled. With regard to pushing the catheter too far and making the balloon too big, the beauty of this catheter design is that if the balloon encounters any resistance to its inflation, the additional air pressure will pop off into the pressure pop-off device built into the catheter. And I am pleased to report that there has yet to be a perforation of a coronary sinus using this particular catheter. Even my residents can put this in and not do any harm. Finally, as to the amount of cardioplegia, we use a bolus technique of cardioplegia, not continuous. We find the bolus technique much easier to use. We have tried continuous retrograde cardioplegia but, unfortunately, you have to use snares around the coronary arteries because the coronary arteries, of course, are the egress for some of this cardioplegia, and you have a constant little drip bothering you. So this report details intermittent doses of cardioplegia.