Assessment of Right Ventricular Function Postretrograde Cardioplegia by Transesophageal Echocardiography

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Assessment of Right Ventricular Funct-ionPostretrograde Cardioplegia by Transesophageal Echocardiography

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Ghassan M. Baslaim, M.D., Thao T. Huynh, M.D., Jim A. Stewart, M.D., Chantal Benny, R.T., Danielle Cusson, R.T., and Jean-Francois Morin, M.D. Division of Cardiothoracic Surgery and Cardiology, The Montreal General Hospital/McGill University, Montreal, Quebec, Canada ABSTRACTThe impact of continuous retrograde cardioplegia (RCP) on right ventricular (RV)function was evaluated prospectively with intraoperative transesophageal echocardiography (TEE) in 36 patients (23 males, 13 females) with a mean age of 60.4 years (ages 24-82). Operative procedures included 12 aortic valve replacements, 16 mitral valve repair/replacements, both with or without an associated cardiac operation, and 8 Ross procedures. Mean cardiopulmonary bypass (CPB)time was 123.3 minutes (66-280 minutes) with an average cross-clamp time of 88.9 minutes (43-199 minutes). The amount of cold blood RCP ranged from 3160-18.500 mL (mean = 7382.51, and the average pulmonary artery pressure was 35/18 mmHg. The coronary sinus was distally snared in 11 patients. TEE documented biventricular global dysfunction in t w o patients and postCPB with preservation of the left ventricular function in all other patients. Localized akinesis of the RV apex and outflow tract were noted in three patients, and isolated worsening tricuspid insufficiency of moderate t o severe intensity in six patients. Two of the six patients with worsening tricuspid insufficiency belonged t o the snared coronary sinus group (11 patients). All of the documented RV dysfunctions were new and showed no correlation with the perfusion data. In conclusion: (1) RV apex, RV outflow tract and tricuspid valve were particularly subject t o important dysfunction post-RCP; (2) RCP did not protect RV adequately in 11 patients (31%); and (3) TEE is a convenient intraoperative technique in evaluating RV dysfunction. (J Card Surg 1998;13:32-36) Retrograde cardioplegia was described earlier in 1956 by Lillehei and colleagues for an aortic valve operation, and since that time it has been extensively studied for it’s safety and effectiveness. In 1990, Drinkwater and associates1reported the use of a coronary sinus catheter with a self-inflating balloon that can be inserted into the coronary sinus without the need for direct visualization. It is

Presented as a poster at the 49fh annual meeting of the Canadian Cardiovascular Society, Montreal, Quebec, October 29 to November 2, 1996. Address for correspondence: J.F. Morin, M.D., The Montreal General Hospital, 1650 Cedar Avenue, Room #L9-112, Montreal, Quebec, Canada H3G 1A4. Fax: (514) 934-8210.

an approach based largely on an understanding of the coronary venous system and arterial anatomy where approximately 75% of venous drainage in the heart occurs. However, in a number of patients, the right ventricular (RV) venous drainage is by Thebesian veins and right coronary veins that drain directly into the ventricular cavity.*t3 The advantages of retrograde cardioplegia are well described in many cardiovascular surgical conditions such as redo-aortocoronary bypass, high-grade stenosis of the main coronary arteries, aortic valve replacement, and surgery of the ascending aorta where adequate cardioplegia delivery is accomplished without interfering with the operation 3 5

BASLAIM, ET AL. RIGHT VENTRICULAR DYSFUNCTION

J. CARD SURG 1998;13:32-36

Most of the clinical studies have focused on the effectiveness of retrograde cardioplegia delivery to the left ventricle, and the question of adequate RV perfusion remains unanswered.2.6 Although metabolic analysis and contrast echocardiography have shown that retrograde cardioplegia provides inadequate protection of RV myocardium, the impact of this inadequacy leading to postoperative RV dysfunction on clinical outcome is still controversial.7 Although transesophageal echocardiography (TEE) has emerged as a powerful intraoperative monitoring tool for left ventricular function, its use in monitoring RV function, particularly with retrograde cardioplegia, has not been adequately studied.8 In this prospective study, w e used TEE to evaluate the RV function postretrograde cold blood cardioplegia and to document the incidence and the quality of the RV dysfunction. MATERIALS AND METHODS Patient population

Thirty-six patients (23 males, 13 females) were enrolled in the study with a mean age of 60.4 years (range = 24-82 years). Twelve patients from this group underwent aortic valve replacement, 16 had mitral valve repairheplacement, both with or without an associated cardiac operation, and 8 underwent Ross procedures. The type of operations are listed in Table 1.

TABLE 1 Operations Performed (36 Patients) Procedure

No. ~

AVR AVR + root enlargement AVR ascending aortic replacement AVR + ascending aortic replacement + ACBP AVR + MVr MVR MVr MVR + TVr MVr + ACBP MVr + l V r Ross

+

8 1 1 1 1

6 4 1 4 1 8

AVR = aortic valve replacement; ACBP = aortocoronary bypass; MVr = mitral valve repair; MVR = mitral valve replacement; TVr = tricuspid valve repair.

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Operative technique

After median sternotomy and systemic heparinization, standard cannulation through the ascending aorta (6.5 mm, Stockert), and right atrium (52/36-French Polystan AJS) or bicaval (26-32French 3M, Sarns Inc., Ann Arbor, MI, USA) cannulation was done. An aortic antegrade cardioplegia cannula (12 gauge, Medtronic Inc.,Minneapolis, MN, USA) was placed in all patients, and a retrograde cardioplegia cannula (15-French, Medtronic Inc.) was positioned using the closed transatrial technique. The coronary sinus, in 11 randomly selected patients, was snared distally from outside after positioning the retrograde cardioplegia cannula using 2/0 prolene. Patients were put on full cardiopulmonary bypass (CPB) and the heart was arrested with cold blood cardioplegia (8-15°C a t 300 mL/min) given through the antegrade cannula. When the heart arrested, the cardioplegia line was switched to the fluid-filled retrograde cardioplegia cannula and cold blood cardioplegia (8-15°C at 100-150 mU min with a pressure of 20-40 mmHg) then was infused continuously. At the end of the procedure the retrograde cardioplegia was stopped, the aortic cross-clamp was removed, and the heart was vented using the aortic antegrade cardioplegia cannula. Total CPB time ranged from 66 to 280 minutes (mean = 123.31, and the average cross-clamp time was 88.9 minutes (range = 43-199 minutes). The amount of the retrograde cardioplegia given ranged from 3160-18,500 mL, with a mean of 7382.5 mL.

Echocardiographicassessment

Omniplane TEE probe (Hewlett-Packard 1000, Andover, MA, USA) was inserted after anesthesia induction and intubation. The echocardiographic assessment (TEE)was performed prior to cannulation and repeated after weaning of CPB. Thorough echocardiographic examination was performed with scanning of both ventricles from 0" to 180". All examinations were recorded on VHS tape and analyzed first online, then offline by two independent echocardiographers blinded to the patients' clinical outcomes. The following views were obtained in all patients: four chamber at 0", .transgastric at 0", and short axis at 120". These views were selected because they pro-

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BASLAIM, ET AL. RIGHT VENTRICULAR DYSFUNCTION

J. CARD SURG

1998;13:32-36

vided complete visualization of the whole RV (inflow, outflow, and apex). The quality of all the echos were satisfactory for analysis in all patients. The RV was divided into three segments: inflow, outflow, and apex. Regional wall scoring was performed: normal contraction, hyperkinesis, hypokinesis, akinesis, dyskinesis, or aneurysmal motion. The left ventricular regional wall motion also was scored using the same system. Valvular evaluation was performed, in particular, the tricuspid valve function was assessed in the four-chamber view. In this view, because the ultrasonic beam was parallel to the tricuspid annulus (angle of incidence: 0") the severity of the tricuspid regurgitation would be the most accurately assessed. Quantitative assessment of the tricuspid regurgitation was done by color flow jet area mapping. The echocardiographic findings related to the RV function observed postretrograde cardioplegia are the following: (1) preserved function; (2) new significant tricuspid regurgitation (moderate to severe); (3)new RVapical and outflow tract akinesia; and (4) new biventricular dysfunction. Although the assessment of RV function was mainly qualitative and by visual estimate, the interpretations were consistent between two independent echocardiographers blinded to the patients' clinical outcome. RESULTS

The pulmonary artery pressure range was 31/ 20-63/35 mmHg for the RV dysfunction group

and 2311 5-77/33 mmHg for non-RV dysfunction group. The average aortic cross-clamp time and CPB time were 84.2 minutes and 119.5 minutes versus 91 minutes and 125 minutes for the RV dysfunction group versus the non-RV dysfunction group, respectively. Five patients had a concomitant coronary artery bypass graft (CABG) procedure with two of them belonging to the RV dysfunction group. The other 31 patients had normal coronary anatomy (Tables l and 21. The data was analyzed according to the echographic findings where the TEE assessment showed an isolated worsening of tricuspid valve regurgitation (moderate to severe) in six patients, biventricular dysfunction in two patients, and akinesia of the right ventricular apex and/ or outflow tract in three patients. The left ventricular function was preserved in 34 patients (Table 2). The incidence and the severity of RV dysfunction in the 11 patients had no correlation with the recorded preoperative pulmonary artery pressure. Only two patients belonging to the snared coronary sinus group suffered from RV dysfunction as moderate to severe tricuspid regurgitation. Because there was no hemodynamic compromise postoperatively, no immediate follow-up echocardiographic assessment was required regarding the documented RV dysfunction, and w e have considered doing this assessment in our further study.

TABLE 2 Echographic Findings of RV Dysfunction (11 Patients) Age 33 79 71 77 49 58 58 54 61 72 32

Sex

F F F M M M M F M M M

Procedure

MVR AVR AVR + RE AVR MVr Ross procedure MVr AVR + ACBP + As.AoR MVR + W r MVr + Wr MVr + ACBP MVr

+

RV dysfunction

PASiPAD (ipob

rn-s TR rn-s TR rn-s TR rn-s TR rn-s TR rn-s TR RVOT + APEX AK. RVOT + APEX AK. RVOT + APEX AK. BIV. DYSFX. BIV. DYSFX.

54/27 34119 25110 33/22 26113 36113 3 1/20 49/25 33115 63/35 41/26

MVR. MVr. AVR, Wr, ACBP = see Table 1. RE = root enlargement; As.AoR = ascending aortic replacement: m-sTR = moderate-severe tricuspid regurgitation: RVOT + APEX AK. = right ventricular outflow tract & apical akinesia: BIV. DYSFX. = biventricular dysfunction; RV = right ventricle; = snared coronary sinus: PAS = pulmonary artery systolic; PAD = pulmonary artery diastolic; ipo = immediate postoperative.

BASLAIM, ET AL. RIGHT VENTRICULAR DYSFUNCTION

J. CARD SURG

1998;13:32-36

CONCLUSIONS The advantages of retrograde cardioplegia include obviation of operation interruptions, reduced risk of flushing air or debris from coronary arteries, and more even distribution of cooling, particularly in the presence of coronary artery disease. The use of retrograde coronary sinus perfusion during aortic valve surgery avoids injury to the coronary ostia and thus eliminates the risk of intraoperative dissection or late ostial stenosis.9 In redo-CABG, retrograde cardioplegia may avoid distal embolization of atheromatous material. It is also a convenient and effective method of myocardial preservation in replacement of ascending aorta or aortic valve or b ~ t h . ~ , ’ ~ - ~ ’ In spite of its usefulness, there is controversy regarding the RV protection during retrograde delivery of cardioplegia. A few studies have demonstrated the adequacy of myocardial perfusion when using retrograde cardioplegia and reported normal RV function in aortic valve and myocardial revascularization Others found that retroplegia alone is a suboptimal technique of myocardial p r ~ t e c t i o n .LeBoutillier ~ Ill and colleagues’s reported the negative effect of retrograde warm continuous cardioplegia on RV function in their studies. Christakis et a1.16 attributed the early transient RV dysfunction following elective CABG to inadequate protection using antegrade cold crystalloid cardioplegia. In this study, 11 patients suffered from RV dysfunction postoperatively. We found no correlation between the type of operative procedure, CPB time, the amount of cold blood cardioplegia or the pulmonary artery pressure, and the occurrence of the RV dysfunction. Ventricular dysfunction can occur in the form of a left, right, or biventricular failure. Left ventricular dysfunction causing low output syndrome is a well-known clinical entity and can be due to ischemia, increased afterload, decreased preload, coronary artery embolism, inadequate myocardial protection, or reperfusion injury. Isolated or concomitant RV dysfunction can lead to low output postoperatively as a result of ischemia, increased pulmonary artery pressure, inadequate protection, or air embolism. We found that TEE is very useful in evaluating RV function intraoperatively where the findings enable understanding of the hemodynamics and help in management. At the present time, there are no valid quantitative for-

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mulae for assessment of RV function by TEE. We propose the following echocardiographic criteria to quantitate the RV function: (11 normal or preserved function; (2) new moderate to severe tricuspid regurgitation; (3)new RV apical and outflow tract akinesia; and (4) new biventricular dysfunction. In this study we demonstrated that the RV apical and outflow tract areas are the most vulnerable regions. There are three major venous drainage pathways of the RV. The Thebesian system shunts directly into the RV cavity and leads to endocardial cooling. The anterior cardiac vein drains the anterior wall of the RV. The posterior interventricular vein drains the posterior two-thirds af the ventricular septum. The latter two systems empty directly into the terminal segment of the coronary sinus close to its entry into the right atrium.g.14To optimize RV protection, the balloon catheter should be positioned close to the orifice of coronary sinus. Using angiographic and electronbeam computed tomography studies17 the previously described findings were confirmed where the RV free wall was not retrogradely perfused because of the thebesian venous drainage system that empties directly into the RV cavity and the posterior descending vein was only perfused in the group that had external coronary sinus occlusion. In 11 of our patients, w e modified the retrograde cardioplegia delivery technique by snaring the coronary sinus, aiming for better perfusion of the RV venous system, and hoping to minimize the incidence of RV dysfunction. This could be explained by the fact that the posterior descending vein, which originates proximal to the balloon, was better perfused with this technique and maximized the septa1 p e r f ~ s i o n .Two ’ ~ patients in this group had RV dysfunction in the form of moderate to severe tricuspid regurgitation not affecting the apex or the outflow tract of the RV, which could be seen as better retrograde venous perfusion. We conclude that TEE is a convenient tool that can be used to assess myocardial function postretrograde cardioplegia perfusion. Because of the RV dysfunction that w e detected, with no major detrimental effect on clinical outcome, retrograde cardioplegia can still be considered a safe technique for the majority of patients undergoing complex heart operations. However, many of our patients demonstrated RV dysfunction by TEE early postoperatively, despite of the fact that

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BASLAIM, ET AL. RIGHT VENTRICULAR DYSFUNCTION

none had preoperative RV dysfunction. In our series, we found no correlation b e t w e e n the incidence of RV dysfunction and t h e recorded pulmonary artery pressure. However, in patients with high pulmonary vascular resistance, such postoperative RV dysfunction m a y adversely affect clinical outcome.

REFERENCES 1. Drinkwater DC, Laks H, Buckberg GD: A new simplified method of optimizing cardioplegic delivery without right heart isolation. J Thorac Cardiovasc Surg 1990;100:56-64. 2. Partington MT, Acar C, Buckberg GD, et al: Studies of retrograde cardioplegia. I. Capillary blood flow distribution to myocardium supplied by open and occluded arteries. J Thorac Cardiovasc Surg 1989;97:605-612. 3. Gates RN, Laks H, Drinkwater DC, et al: The microvascular distribution of cardioplegic solution in the piglet heart. Retrograde versus antegrade delivery. J Thorac Cardiovasc Surg 1993;105:845-53. 4. Partington MT, Acar C, Buckberg GD, et al: Studies of retrograde cardioplegia. (I. Advantages of antegradehetrograde cardioplegia to optimize distribution in jeopardized myocardium. J Thorac Cardiovasc Surg 1989;97:613-622. 5. Chitwood WR, Wixon CL, Norton TO, et al: Complex valve operations: Antegrade versus retrograde cardioplegia?. Ann Thorac Surg 1995:60: 815-818. 6. Noyez L, van Son JAM, van der Werf T, et al: Retrograde versus antegrade delivery of cardioplegic solution in myocardial revascularization. J Thorac Cardiovasc Surg 1993; 105:854-863. 7 . Allen BS, Winkelmann JW, Hanafy H, et al: Retrograde cardioplegia does not adequately perfuse the right ventricle. J Thorac Cardiovasc Surg 1995; 109:1116-1 126.

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8. Davila-Roman VG, Waggoner AD, Hopkins WE, et al: Right ventricular dysfunction in low output syndrome after cardiac operations: Assessment by transesophageal echocardiography. Ann Thorac Surg 1995;60:1081-1086. 9. Fiore AC, Naunheim KS, McBride LR, et al: Aortic valve replacement: Aortic root versus coronary sinus perfusion with blood cardioplegic solution. J Thorac Cardiovasc Surg 1992;104:130-138. 10. Snyder HE, Smithwick W 111, Wingard JT, et al: Retrograde coronary sinus perfusion. Ann Thorac Surg 1988;46:389-390. 11. Bhayana JN, Kalmbach T, Booth FVM, et al: Combined antegradehetrograde cardioplegia or myocardial protection: A clinical trial. J Thorac Cardiovasc Surg 1989;98:956-960. 12. Menasche P, Fleury JP, Dorce L, et al: Metabolic and functional evidence that retrograde warm blood cardioplegia does not injure the right ventricle in human beings. Circulation 1994;90(Part 2):ll310-11-315. 13. Douville EC, Kratz JM, Spinale FG, et al: Retrograde versus antegrade cardioplegia: Impact on right ventricular function. Ann Thorac Surg 1992; 54:56-61. 14. Menasche P, Kucharski K, Mundler 0, et al: Adequate preservation of right ventricular function after coronary sinus cardioplegia: A clinical study. Circulation 1989;8O(Suppl111):111-19-111-24. 15. LeBoutillier Ill M, Grossi EA, Steinberg BM, et al: Effect of retrograde warm continuous cardioplegia on right ventricular function. Circulation 1994; 9O(Part 2):11-306-11-309. 16. Christakis GT, Fremes SE. Weisel RD, et al: Right ventricular dysfunction following cold potassium cardioplegia. J Thorac Cardiovasc Surg 1985;90: 243-250. 17. Farge A, Mousseaux E, Acar C, et al: Angiographic and electron-beam computed tomography studies of retrograde cardioplegia via the coronary sinus. J Thorac Cardiovasc Surg 1996;112:1046-I053.

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