Protection of the right ventricle: comparison of retrograde with antegrade cardioplegia

Protection Of The Right Ventricle: Comparison Retrograde With Antegrade Cardioplegia D.A.C.Sharpe*,

FRCS, S.Jeya+, FRCA, M.V.Shah+,

FRCA, J.Berridge+,

FRCA, C.M. Munsch*,

Of FRCS

Department of Cardiothoracic Surgery* and Department of Anaesthesia” The General Infirmary at Leeds, Great George Street, Leeds, United Kingdom

T he

adequacy of right ventricular (RV) preservation and cooling with retrograde cardiopjegiahas been questioned. We compared the effects of retrograde with antegrade cardioplegia on the recovery of right ventricular function in patients undergoing coronary artery surgery. Two groups of similar age, left ventricular function and extent of disease received either retrograde (RC) or antegrade (AC) multidose cold-blood cardioplegia. A right ventricular rapid-response catheter measured right ventricular haemodynamics before and after bypass. Needle thermistors recorded intramyocardial temperatures in the right ventricular free wail, the left ventricular free wall and the septum. There were no differences in bypass times, ischaemic times, inotrope requirements or arrhythmia frequency between the 2 groups. RV haemodynamics were similar in both groups before bypass. Immediately after bypass the RV end diastolic volume index was lower in the retrograde group than in the antegrade group, and RV ejection fraction was higher. This indicates better RV preservation with retrograde cardioplegia early after bypass. By 30 min after bypass all haemodynamic variables had returned to baseline values in both groups. Retrograde cardioplegia provided effective cooling in all areas of the heart. The mean time to achieve electromechanical quiescence was longer with retrograde cardioplegia, and a larger total volume of cardioplegia was required. Except for a minor advantage for RC soon after bypass, this study suggests that RV protection during coronary artery surgery is the same whether retrograde or antegrade cardioplegia is used. The time taken to achieve diastolic arrest with retrograde cardioplegia may persuade surgeons that a combination of antegrade and retrograde cardioplegia remains the most satisfactory technique. (Asia Pacific J Thorac Cardiovasc Surg 1996;5(1):9-13)

Introduction The advantages of retrograde cardioplegia delivery to the left ventricle have been well documented in clinical and experimental studies, providing improved protection to vulnerable areas of the left ventricular myocardium supplied by high grade coronary stenoses.‘,2,3 There remains doubt about the efficacy of right ventricular protection with retrograde cardioplegia. Although relatively little attention has been paid to the right ventricle in the past, it has been shown that it is just as susceptible to ischaemic injury as the left ventricle in terms of function and metabolic recovery.4 Several experimental studies have shown poor distribution of cardioplegia to the right ventricle leading to suboptimal protection, particularly in the absence of topical cooling.-- 5 I2 This has not been a consistent finding. I3 A further problem of retrograde cardioplegia noted in the laboratory was the increased length of time taken to induce complete diastolic arrest.14 To overcome these potential limitations of retrograde cardioplegia, it has been suggested that a combination of retrograde and

antegrade cardioplegia be used.15 This increases the complexity and the expense of the procedure, and in the view of Grundy it is unnecessary, provided retrograde cardioplegia is delivered at the appropriate flow rate.16 Partly as a result of these concerns there has been a slow adoption of retrograde cardioplegia into clinical practice despite its proven advantages. In an attempt to resolve this question, we carried out a randomised clinical study comparing the effects of retrograde delivery of cardioplegia with antegrade delivery on RV preservation. Patients and Methods Eighteen patients (12 male, 6 female) undergoing elective coronary artery bypass grafting for triple coronary artery disease were prospectively randomised, by random selection of treatment protocol sealed envelopes, to receive either antegrade cardioplegia (AC, n = 9) or retrograde cardioplegia (RC, n = 9) for myocardial protection. No attempt was made to blind the single observer to the route of cardioplegia delivery

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Table 1. Preoperative deviation) demonstrating between the 2 groups.

Age Sex (M:F) Left ventricular ejection fraction

Sharpe,

data (mean f standard no significant differences

Retrograde n=9

Antegrade n=9

57.1k7.1 years 8:l

61.1k4.9 years 8:l

39.2f16.7%

51.7+23.3%

Jeya, Shah, Berridge, Munsch Protection of the right ventricle

Table 2. Operative data (mean zks.d.) demonstrating no significant differences between the 2 groups. Retrograde Ischaemic time

49.6k7.87 min

43.4k8.68 min

Cardiopulmonary bypass time

87.917.3 min

72.9k15.4 min

Number of coronary artery bypass grafts

because of the obvious methods involved in theatre during the data collection. Local ethics committee approval was obtained prior to initiation of the study, and all patients gave informed consent. Following the induction of general anaesthesia, central venous and radial arterial catheters were introduced. In addition a right ventricular thermodilution ejection fraction catheter (REF-1, Baxter Health Care Corp., Irvine, CA.) was introduced. The REF-1 catheter is a recent modification of the Swan Ganz catheter with 2 intracardiac electrodes and a rapid response thermistor able to detect changes on a beat-to-beat basis. The catheter is interfaced with a computer which calculates, from the temperature decay profile between 2 successive RV contractions, the end systolic and diastolic volumes and subsequently the ejection fraction and cardiac output. This technique has been shown to correlate well with established techniques for assessing right ventricular function.r7.r8

Antegrade

3.75kO.43

3.44+0.68

induced with 10 mL/kg cold blood cardioplegia (PC!) at a flow rate of 250 mL/min. If arrest had not been achieved by completion of the calculated induction dose, cardioplegia infusion was continued until electromechanical quiescence was achieved; the time to achieve arrest was noted. After the completion of each distal anastomosis, or if any electrical activity was noted, a further dose of 250 mL of cardioplegia was given. The volumes and timing of doses of cardioplegia were noted. Topical cooling of the heart was not employed in this study because of its variable effects. All patients received warm blood cardioplegia reperfusion at a flow rate of 1.50 mL/min for 3 min immediately prior to removal of the cross clamp. The time taken to revert to sinus rhythm was noted. Needle thermistors were placed into the anterior surface of the right ventricular free wall, centrally in the septum from the anterior surface and in the left ventricular free wall. Temperatures were recorded prior to cardioplegia, every minute during the initial cooling phase, every 5 minutes during distal anastomosis construction, following any additional doses of cardioplegia, and every minute during the warm-blood cardioplegic reperfusion.

The following haemodynamic data were collected at each sampling interval: right atria1 pressure, systemic arterial pressure, right ventricular ejection fraction (RVEF), right ventricular end diastolic volume index (EDVI), right ventricular end systolic volume index (ESVI), cardiac index, pulmonary artery pressure and pulmonary capillary wedge pressure. Calculations were performed using a Baxter right ventricular ejection fraction computer. An average of 3 injections at end expiration was always taken for all derived numbers. The sampling intervals were: prior to cardiopulmonary bypass; at the end of cardiopulmonary bypass; after the administration of the protamine sulphate; at 15 min, 30 min, 1 hour, 4 hours, 12 hours and 24 hours after the cessation of cardiopulmonary bypass.

Data were analysed using the Mann-Whitney method for non-parametric data and one-way analysis of variance. All results were expressed as mean + standard deviation, and a p value of less than 0.05 was considered statistically significant. Results The 2 groups were similar in age and sex distribution. The RC group tended to have poorer left ventricular function although this did not reach significance (Table 1). Both groups received similar operations (Table 2). Most patients required no inotropic support (RC group, n =-S; AC, group n = 7). In the AC group 2 patients required inotropic support with adrenaline (maximum dose, 0.22 pg kg-’ min.‘) for the first 24 hours. In the RC group a single patient received inotropic support with dobutamine (maximum dose, 8.9 ug kg-’ min.‘) for 12 hours. All patients left intensive care on the first postoperative day with no inotropic

Aorto-atria1 cardiopulmonary bypass was instituted in a standard manner, using a 2-stage atria1 cannula for venous drainage. Moderate systemic hypothermia (28°C) was employed. In the RC group the coronary sinus was cannulated transatrially using a retrograde coronary sinus perfusion catheter (Research Medical Inc., Salt Lake City, UT). In the AC group an aortic cardioplegia cannula (Research Medical Inc.) was used. After cross clamping of the aorta, diastolic arrest was

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Sharpe, Jeya, Shah, Berridge, Munsch

Asia Pacific .I Thorac Cardiovasc Surg 1996;5(1)

Protection

of the right

ventricle

RVEF %

EDVI mlslminlm2 I

60

120 50 100 40 80 30 60 20 40

- - - antegrade retrograde

20

__------

10

antegrade retrograde

0 0

/

1

I

30 minutes 4 hours 24 hours Pre Bypass Post protamine Post bypass 15 minutes I hour 12 Hours

,

Pre Bypass Post protamine 30 minutes Post Bypass 15 minutes 1 hour

4 hours

24 hours 12 Hours

Fig. 3. Right ventricular ejection fraction (RVEF) for antegrade and retrograde cardioplegia.

Fig. 1. Right ventricular end diastolic volume index (EDVI) for antegrade and retrograde cardioplegia (p
Table 3. Cardioplegia

;

and arrest data (mean + s.d.). Retrograde

Cardioplegia to induce arrest 60

Cardioplegia to maintain arrest

40

Time to arrest

0

L

Time to return to sinus rhythm

antegrade retrograde

__------

20

, 30 minutes Pre Bypass Post protamine Post Bypass 15 minutes I hour

4 hours

1025k259 mL*

Antegrade 688+242 mL

mL

789228.2 mL

3.58k1.58 min*

1.6150.91 min

781f195

12fll.9

min*

32.9+22 min

*Between group difference p
24 hours 12 Hours

Fig. 2. Right ventricular end systolic volume index (ESVI) for antegrade and retrograde cardioplegia (p
After this initial period there were no significant differences in right ventricular function between the 2 groups. There was no significant difference at any time in the right ventricular function within either group.

or in any

The RC group required significantly more cardioplegia to induce arrest but not to maintain it. Arrest was induced significantly more rapidly in the AC group (Table 3). All patients returned to sinus rhythm, although the RC group returned to sinus rhythm significantly more rapidly compared to the AC group. No arrhythmia required therapeutic intervention in the postoperative period. All areas of the heart cooled evenly over 4.1kO.77 min to a mean temperature of 16.1+6.56”C in the AC group and over 4.57&l min to 17.1+5.63”C in the RC group. Myocardial temperature area was maintained at 21.5+4”C in the AC group and 20.3f4.29”C in the RC group. All areas of the heart warmed evenly during the “hot shot” to 34+2.61”C in the AC group and to 29.8f3.03”C in the RC group. There was no significant difference between the cooling and rewarming times, or at any time between any area of the heart within each group or between the 2 groups. Figs. 4, 5 and 6, demonstrate the cooling profile of the 3 areas measured.

There was no significant difference within either group or between the 2 groups at any time for the following haemodynamic parameters: right atria1 pressure (RC, 7.9k3.2 mmHg; AC, 7.7k3.5 mmHg), systemic arterial pressure (RC 76.5fll mmHg; AC, 72.8fllmmHg; cardiac index (RC, 3.3kO.7 L min.‘m-2 AC, 3.2kO.S L min-‘mW2),pulmonary artery pressure (RC, 18.5f4.1 mmHg; AC, 16.5k4.2 mmHg), and pulmonary capillary wedge pressure (RC, 9.7k3.8 mmHg; AC, 9.3k3.2 mmHg). The preoperative and postoperative right ventricular function is demonstrated in Figs. 1, 2 and 3. In the 15 minute period immediately after cardiopulmonary bypass there was a significant difference in EDVI (103k25.9 vs 71.X+20.8 mL rnm2)and ESVI (64.8k25.1 vs 39.8f15 mL mm2)between the 2 groups. There was not a statistically significant difference in RVEF (38k8 vs 45&9%).

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Asia Pacific J Thorac Cardiovasc Surg 1996;5(1)

Sharpe, Jeya, Shah, Benidge, Munsch Protection

Right ventricular free wall 4oc

40 c

of the right

ltum

__-----30 c

ventricle

antegra

3oc

20 c

1

IOC

1

IOC

i

oco

1 minute

oc 2 minutes

3 minutes

4minutes

Fig. 4. Cooling profile of right ventricular antegrade and retrograde cardioplegia.

Sminutes

free wall

Fig. 6. Cooling cardioplegia.

with

- - - antegrade retrograde 3oc

20 c

IOC

oc

Fig. 5. Cooling

2 minutes

3 minutes

4minutes

profile of left ventricular antegrade and retrograde cardioplegia.

3 minutes

4minutes

Sminutes

profile of the septum antegrade and retrograde

When retrograde cardioplegia is given a large proportion of the cardioplegic solution will shunt via the Thebesian sinusoidal system directly to the right ventricular cavity. This may provide intracavity cooling, protecting the right ventricular free wall and the right side of the interventricular septum. With careful coronary sinus catheter placement the remainder of the venous drainage system of the right ventricle, the posterior inter-ventricular vein and the anterior coronary vein will be perfused directly or by collateral flo~.‘,~

5minutes

free wall

2 minutes

cardioplegia and its exposed position during surgery are considered to be important elements in postoperative right ventricular dysfunction. It is suggested that cooling with the cardioplegic solution alone is inadequate in the presence of high grade stenoses. Some authors consider topical hypothermia to be an essential factor for right ventricular myocardial protection6,10 In this study we found that this was not the case. Right ventricular free wall and septal cooling was equally good with both techniques in the absence of topical hypothermia. We could identify no differences in cooling between the right and left ventricles with either technique.

Left ventricular free wall 4oc

I minute

1

1 minute

with

Discussion Right ventricular injury is often perceived as being less frequent and less serious than left ventricular injury. However right and left ventricles appear to be equally susceptible to ischaemic injury during cardiac surgery.4 With improving mechanical and pharmacological support for the left ventricle, the role of right ventricular injury as a major determinant of outcome will become more apparent. Studies directed at right ventricular dysfunction following cardiac surgery have been handicapped due to inadequate and cumbersome investigation techniques. Effective techniques for quantifying right ventricular performance in the clinical setting have recently been developed and now allow this question to be addressed. In this study we found little difference in right ventricular performance postoperatively between the 2 groups. There was marginally superior right ventricular function in the RC group as compared to the AC group (but not when compared to preoperative baseline values). The advantage was short lasting, and after 15 minutes there was no discernible difference between the groups on any of the measured haemodynamic variables. Warming of the right ventricle due to poor flow of

In animal studies Partington found that during RC little nutritive flow was supplied to the right ventricle, particularly the free wall. 6,7They concluded that RC may not be adequate to meet the metabolic demands of the right ventricle if it is the only method of cardioplegia protection. In Partington’s study the coronary sinus catheter was placed far into the coronary sinus, occluding early tributaries.

Canine

coronary

venous

anatomy

is

significantly different from human venous anatomy, the right ventricular free wall being better perfused in humans. These 2 factors may account for the difference in findings between our study and the Partington study. In summary our data suggests that RC provides adequate right ventricular cooling to reduce metabolic demands and sufficient nutritive flow to meet these metabolic demands during cardioplegic arrest. The RC

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5.

group took a significantly longer time and a higher volume of cardioplegia to achieve cardiac arrest than the AC group. The larger dose of cardioplegia may be a factor in the slightly superior right ventricular function in the RC group in the period immediately following cardiopulmonary bypass. Rapid diastolic arrest is a fundamental principle of cardioplegia, minimising depletion of energy reserves by useless work, after the cross clamp has been applied.

6.

7.

8.

Grundy showed that the time to arrest was not significantly different between the 2 routes of cardioplegia administration.16 The longer period of mechanical activity prior to diastolic arrest is a concern that has been identified in other studies but appears to have no impact on preservation. Concern over longer times to achieve arrest is likely to make a combination technique of AC followed by RC the method of choice for most surgeons.

9.

10.

11

Conclusion We conclude that multidose cold-blood retrograde cardioplegia alone provided adequate right ventricular protection in this group of patients with short ischaemic times. Little difference was found in the preservation of right ventricular function with either antegrade or retrograde cardioplegia. It is likely that a combined antegrade/retrograde approach will remain the method of choice for most surgeons.

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14.

15.

References 1.

2.

3. 4.

Menasche P, Subayi JP, VeyssieL, Le Dref 0, Chevret S, Piwnca A. Efficacy of coronary sinus cardioplegia in patients with complete coronary artery occlusions. Ann Thorac Surg 1991;51:418-23. Haan C, Lazar HL, Bernard S, Rivers S, Zallnick J, Shemin RJ. Superiority of retrograde cardioplegia after acute coronary artery occlusion. Ann Thorac Surg 1991;51:408-12. Eng J, Munsch CM. Retrograde cardioplegia. Perfusion 1992;7:712. Moris JJ III, Hamm DP, Pellom MS, Abd-Elfattah A, Weschler AS. Right ventricular sensitivity to metabolic injury during cardiopulmonary bypass. Arch Surg 1986;121:338-44.

“Marlboro

16.

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Jeya, Shah, Berridge, Protection of the right

Munsch ventricle

Salter DR, Goldstein JP, Abd-Elfattah A, Murphy CE, Brunsting LA, Weschler AS. Ventricular function after atria1 cardioplegia. Circulation 1978;76(supplV);V129-40. Partington MT, Acer C, Buckberg GD, Julia PL. Studies of retrograde cardioplegia: II. Advantages of antegradelretrograde cardioplegia. Surg 1989;97:613-22. Partington MT, Acer C, Buckberg GD, Julia P, Kofsky ER, Bugyi HI. Studies of retrograde cardioplegia: I. Capillary blood flow distribution to myocardium supplied by open and occluded arteries J Thorac Cardiovasc Surg 1989;97:605-12. Eichhorn EJ, Diehl JT, Konstam MA, Payne DD, Salem DM, Cleveland RJ. Protective effects of retrograde compared with antegrade cardioplegia on right ventricular systolic and diastolic function during coronary artery bypass graft surgery. Circulation 1989;79:1271-81. Solorzano J, Taitelbaum G, Chiu RCJ. Retrograde sinus perfusion for myocardial protection during cardiopulmonary bypass. Ann Thorac Surg 1978;25:201-8. Rabinovitch MA, Elstien J, Chu-Jeng Chiu R, Rose CP, Arzoumanian A, Burgess JH. Selective right ventricular dysfunction after coronary artery bypass grafting. J Thorac Cardiovasc Surg 1983;86:444-5. Douville EC, Kratz JM, Spinale FG, Crawford FA Jnr, Alpert CC, Pearce A. Retrograde vs antegrade cardioplegia: impact on right ventricular function. Ann Thorac Surg 1992;54:56-61. Menasche P, Kucharski K, Mundler 0, Veyssie L, Subayi JB, Le Pimpel CF, Fauchet M, Piwnica A. Adequate preservation of right ventricular function after coronary sinus cardioplegia: a clinical study. Circulation 1989;80(supp1111):11119-24. Goldstein JP, Salter DR, Murphy CE, Abd-Elfattah A, Moris JJ, Weschler AS. The efficacy of blood versus crystalloid coronary sinus cardioplegia during global myocardial ischaemia. Circulation 1986;74(supplIII):III99-104. Buckberg GD. Antegrade/retrograde cardioplegia to ensure cardioplegic distribution: operative techniques and objectives. J Cardiac Surg 1989;4:216-38. Grundy SR, Kirsh MM. A comparison of retrograde versus antegrade cardioplegia in the presence of coronary artery obstruction. Ann Thorac Surg 1984;38: 124-7. Vincent JL, Thirion M, Brimioulle S, Lejeune P, Kahn RJ. Thermodilution measurement of right ventricular performance with a modified pulmonary artery catheter. Int Care Med 1986;12:33-8. Dhainaut JF, Brunet F, Monsallier JF, Villemant D, Devaux JY, Konno M. Bedside evaluation of right ventricular performance using a rapid computerised thermodilution method. Crit Care Med 1987;15:148-52. Spinale FG, Smith AC, Carabello BA, Crawford FA. Comparison of thermodilution and ventriculographic methods for the determination of right ventricular function. J Thorac Cardiovasc Surg 1990;99:141-52.

Man” dies of cancer

David McLean, a rugged actor who, for many years, portrayed the Marlboro Man in television cigarette commercials, has died at the age of 73 from lung cancer. A spokesperson said McLean, who also appeared in movies and in television Westerns, died on October 12 at the University of California, Los Angeles, Medical Center. He was the second “Marlboro Man” to die of lung cancer in recent years. Wayne McLaren, who appeared as

the cowboy in print and billboard advertisements for Philip Morris, Inc, the makers of Marlboro, died in 1992 at the age of 51. McLean appeared in small roles in a series of television Westerns including Gunsmoke, Bonanza, High Chaparral and The Virginian. His movie credits include The Andromeda Strain in 1971 and Nevada Smith in 1975. He is survived by his wife, Lilo, and son, Mark. Reuter

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