Ann Thorac Surg 2001;72:1572-1575
© 2001 The Society of Thoracic Surgeons
Original article: cardiovascular
Does warm blood retrograde cardioplegia preserve right ventricular function?
Pankaj Kulshrestha, MDa,
John A. Rousou, MD*a,
Richard M. Engelman, MDa,
Joseph E. Flack, III, MDa,
David W. Deaton, MDa,
Richard B. Wait, MDa,
Heather M. Hampf, BSa
a Division of Cardiac Surgery, Department of Surgery, The Baystate Medical Center, Springfield, Massachusetts, USA
Accepted for publication July 31, 2001.
* Address reprint requests to Dr Rousou, Division of Cardiac Surgery, Baystate Medical Center, 759 Chestnut St, Springfield, MA 01199, USA
e-mail: cardiac51{at}worldnet.att.net
 |
Abstract
|
|---|
Background. Efficacy of warm blood retrograde cardioplegia in preserving right heart function remains controversial. The current study was conducted to gauge the preservation of right ventricular function after warm blood retrograde cardioplegia.
Methods. We studied 75 consecutive patients undergoing isolated heart valve procedures with warm blood retrograde cardioplegia as the exclusive mode of preservation. Right ventricular radionuclide ejection fraction and hemodynamic measurements using a pulmonary artery catheter were calculated before and within 3 days after operation.
Results. Postoperative radionuclide right ventricular ejection fraction was well preserved at 0.4686 ± 0.0122 compared with 0.4327 ± 0.0255 preoperatively (p = 0.7064). Right ventricular systolic work index improved from 5.82 ± 0.52 to 8.97 ± 0.60 g-m/m2 (p < 0.0001) and cardiac index increased from 2.40 ± 0.09 to 2.92 ± 0.11 L/m2 (p < 0.0001). When right ventricular systolic work index was correlated with preload, 30 patients moved up and down on the same ventricular function curve and 42 moved to a higher inotropic curve postoperatively. Only 3 patients demonstrated decreased inotropy.
Conclusions. In the clinical setting warm blood retrograde cardioplegia used as the exclusive mode of myocardial preservation provides adequate protection of the right heart.
|
Introduction
|
|---|
Retrograde warm blood cardioplegia (WBRC) has recently been increasingly used for myocardial preservation. The procedure avoids the side effects of hypothermia, and provides a more effective supply of oxygen and better distribution of a less viscous solution [1, 2]. However, efficacy of WBRC in preserving right ventricular (RV) function remains controversial. Contrast echocardiographic studies have shown inadequate retrograde delivery of cardioplegic solution to RV free wall [3, 4]. The effect on RV function of WBRC used as the exclusive mode of myocardial preservation has not been studied adequately [5, 6]. To determine the impact of WBRC, we prospectively compared preoperative and postoperative RV function in 75 patients undergoing isolated valve replacement or repair using WBRC exclusively.
|
Material and methods
|
|---|
Seventy-five consecutive patients undergoing isolated valve replacement or repair at Baystate Medical Center over a 12-month period were studied. Patients requiring concomitant coronary artery bypass procedures were excluded. Mortality, morbidity, use of inotropic agents, and electrocardiograms were recorded prospectively.
Operative technique
Cardiopulmonary bypass was established using an aortic cannula and a two stage venous cannula for aortic valve replacement and two separate venous cannulas for mitral valve replacement (MVR), mitral valve repair, or double valve replacement. A retrograde coronary sinus cardioplegic catheter (DLP Inc, Grand Rapids, MI) was introduced through a pursestring suture in the right atrium and guided into the coronary sinus bimanually. The perfusate was kept at 32°C while cardioplegia was kept at normothermia (37°C). The initial arrest was achieved with an antegrade bolus of warm blood cardioplegia except in patients with severe aortic insufficiency, in whom retrograde induction was used exclusively (n = 13). A single dose of 300 to 500 mL of antegrade cardioplegia was given over a period of 2 minutes only once at the beginning of the cross-clamp and was not repeated during the rest of the procedure. Cardiac arrest was maintained using continuous WBRC at the rate of 200 to 350 mL per minute. The pressure in the coronary sinus was maintained between 20 and 80 mm Hg. Cardioplegia was interrupted for variable periods of up to 10 minutes to obtain a bloodless field during valve excision or implantation whenever necessary. Patients were rewarmed to 37°C before being weaned off extracorporeal circulation. Hematocrit was maintained above 20% during cardiopulmonary bypass.
Radionuclide study
All studies were conducted within 72 hours before and after the operation. Radionuclide studies were performed on postoperative day 2 in 69 patients and day 3 in 6 patients. We assessed global and segmental RV function by first pass and gated blood pool radionuclide angiocardiography using technetium T-99m-labeled red blood cells (MUGA). These postoperative studies were conducted after all inotropic agents were discontinued. Preoperative and postoperative right ventricular ejection fraction (RVEF) were calculated in all cases.
Hemodynamic monitoring
The hemodynamic monitoring was performed using a multilumen thermodilution catheter (Baxter Healthcare Corp, Irvine, CA) inserted into the pulmonary artery before induction of anesthesia. Hemodynamic measurements recorded include heart rate, mean arterial pressure (MAP), right atrial pressure (RAP), pulmonary artery pressures (PAP), pulmonary capillary wedge pressure, and cardiac output. The calculated measurements included cardiac index (CI), pulmonary vascular resistance index, and right ventricular systolic work index (RVSWI), left ventricular systolic work index, and systemic vascular resistance index. The RV functions were assessed immediately before induction of the anesthesia and before removal of the pulmonary artery catheter postoperatively after inotropic agents (if used) had been discontinued. Postoperative measurements were made on postoperative day 2 in 58 patients and day 3 in 17 patients. The change in preoperative to postoperative RVSWI was correlated with the corresponding change in RAP. Based on this correlation the patients were classified into various groups I to VI (Table 3). The direction of movement of RAP-RVSWI relation from preoperative to postoperative period for 75 patients is diagrammatically depicted in relation to a set of 3 hypothetical ventricular function curves as described by Sarnoff and Berglund [7] (Fig 1). An attempt was made to determine whether a particular patient moved up and down along the same ventricular function curve as preoperatively or moved to an entirely different curve of higher or lower inotropic state (Fig 1).
View larger version (15K):
[in this window]
[in a new window]
|
Fig 1. Direction of movement of RAP-RVSWI relation (arrows) from preoperative to postoperative period for 75 patients depicted in relation to a set of three hypothetical ventricular function curves (A, B, C). Point O represents the preoperative position of RAP-RVSWI relation. Groups II and III move toward curve C to the left, indicating improved RV function; groups V and VI move toward curve B to the right, indicating decreased contractility; and groups I and IV move up and down along the same curve A, indicating unchanged inotropic state. Only 3 patients in group VI had decreased contractility. (GP = group; RAP = right atrial pressure; RVSWI = right ventricular systolic work index.) (Data adapted from Sarnoff and Berglund [7].)
|
|
Statistical analysis
Comparisons between preoperative and postoperative data were made by a paired t test. A p value of less than 0.05 was considered statistically significant. All results are reported as the mean ± standard error of the mean.
|
Results
|
|---|
Clinical and hemodynamic data
There were 41 men and 34 women in the study. The mean age was 65.43 ± 1.42 years (range 28 to 85 years). The New York Heart Association functional class distribution was as follows: Class II, n = 25; Class III, n = 46; and Class IV, n = 4. The mean preoperative systolic PAP as calculated by Doppler echocardiogram was 54.66 ± 6.96. Forty-two of 75 patients had some degree of pulmonary artery hypertension as indicated by mean PAP of more than 20 mm Hg. The degree of mitral regurgitation was graded on preoperative echocardiogram as severe in 15 patients, moderate in 13 patients, mild in 23 patients, and absent in 24 patients. All aortic valve replacement patients (n = 46) had left ventricular hypertrophy, whereas 13 of 19 MVR patients had pulmonary hypertension (mean PAP higher than 20 mm Hg). The operations performed are shown in Table 1. The average aortic clamp time and cardiopulmonary bypass time were 87 ± 3 minutes (range 46 to 201 minutes) and 116 ± 4 minutes (range 57 to 244 minutes), respectively. There were no deaths. One patient developed RV failure postoperatively and 17 required inotropic support for CI less than 2.2 or mean blood pressure less than 55 mm Hg. Inotropic support was discontinued in all patients within 48 hours. No patient was noted to have evidence of significant myocardial infarction on electrocardiogram. The average intensive care stay was 34 ± 2 hours and mean length of hospital stay was 8 ± 1 days. The average RAP remained unchanged from the preoperative value (Table 2). Mean RVSWI and CI were significantly improved postoperatively (Table 2).
Radionuclide studies
The postoperative MUGA RVEF did not change significantly (p = 0.70) from preoperative value (Table 2). No new segmental wall motion abnormalities were noted.
Stroke work—preload correlation
The change in RVSWI was correlated with corresponding change in RAP in individual patients. Based on this correlation the patients were divided into six categories (Table 3). Patients with increased RVSWI in association with increased, unchanged, or decreased RAP (groups I to III) were considered to have unchanged or improved RV functions. Similarly, those with a decrease in both RAP and RVSWI (group IV) had unchanged RV functions. Patients with unchanged or increased RAP (groups V and VI) in association with diminished RVSWI characterized the group with postoperative deterioration of RV function. Figure 1 shows the direction of movement of RAP-RVSWI relation from preoperative to postoperative period for 75 patients with respect to a set of three hypothetical ventricular function curves as described by Sarnoff and Berglund [7]. Deterioration of RV function was noted in 3 patients (Fig 1, group VI).
|
Comment
|
|---|
The advantages of retrograde cardioplegia include delivery beyond coronary stenosis and freedom from air and atheroembolism. Retrograde cardioplegia also obviates the need to cannulate the coronary ostia and allows manipulation of the heart during cardioplegia delivery. Warm blood cardioplegia avoids the harmful effects of hypothermia and allows better distribution and utilization of oxygen during cardiac arrest [1, 2]. However, controversy persists regarding the ability of retrograde cardioplegia to protect RV function adequately, particularly when used as the exclusive mode of delivery for the hypertrophied heart at normothermia [8–10]. Studies on dogs have documented poor distribution of cardioplegia to the RV [8]. Clinically we have not encountered increased RV dysfunction with the use of WBRC in all operations during the last 9 years. The current study was conducted to test the validity of this clinical impression.
Patients undergoing isolated valvular procedures were studied to avoid the confounding effect of cardioplegia delivered through coronary grafts, as is usually the case in coronary bypass operations. A one-time dose of antegrade cardioplegia was used initially to obtain a rapid induction of cardiac arrest. The diastolic arrest was maintained exclusively by warm blood cardioplegia given retrogradely. Contrary to previous reports [9], no attempt was made to position the tip of the coronary sinus catheter in the terminal portion of the coronary sinus. A high volume of cardioplegic solution ranging from 200 to 350 mL per minute was administered (especially in hypertrophied hearts) while accepting coronary sinus pressure as high as 80 mm Hg. It should be noted that a flow of 200 to 300 mL per minute in a well-placed coronary sinus catheter does not generate a pressure of 80 mm of Hg with the heart in a neutral position. During the retraction of heart for MVR the coronary sinus pressure may be allowed to increase to 80 mm Hg. Some of this elevation may be artifact; however, we do not stop or decrease the flow of the cardioplegia until the pressure reads 80 mm Hg. This must be distinguished from the situation in which cardioplegia pressure tends to rise steeply with even a small amount of flow. Clinical judgment must be used and the adequacy of cardiac venous filling must be assessed constantly. During the course of the operation, cardioplegia was interrupted several times for intervals of up to 10 minutes as long as these periods were followed by a period of uninterrupted retrograde delivery for at least 3 to 5 minutes. We believe that attention to such details is crucial to achieving adequate myocardial preservation with WBRC.
Our clinical results indicate absence of mortality and low morbidity in the entire group. Seventeen patients required inotropic or pressor support. Most of these patients had low MAP along with normal or high CI requiring inotropic agents to maintain adequate MAP. This finding is consistent with the well-known vasodilatory effect of warm heart surgical procedures [10–12]. The overall radionuclide RVEF was well preserved. Hemodynamically the group showed a significantly improved RVSWI and CI in the face of unchanged preload or RAP. It is possible that our study missed transient RV dysfunction in the early postoperative period; however, such dysfunction did not reach clinical significance.
To assess RV function in an individual patient the RVSWI must be correlated with mean RAP. Thus, the change in RVSWI from the preoperative to postoperative period must be viewed in light of the corresponding change in RAP. This is done by assessing the relative position on ventricular function curves, which plot the relation between RAP (or RV end-diastolic pressure) and RVSWI as described by Sarnoff and Berglund [7]. At least 2 values of RAP and RVSWI are needed to draw a curve. We were not able to plot these curves because we had only one set of values both preoperatively and postoperatively. Using ventricular function curve concept, and having only two points of information about heart function, often it is possible to infer whether or not an intervention has caused a change in inotropic state [13]. Therefore we depicted the direction of movement of RAP-RVSWI relation from the preoperative to postoperative period on a set of three hypothetical ventricular function curves (Fig 1). The point O on hypothetical curve A represents the preoperative position of RAP-RVSWI relation. The arrows in Figure 1 indicate the postoperative direction of movement of RAP-RVSWI relation and the number of patients moving in each direction. Postoperatively the RAP-RVSWI relation may move to the left toward the hypothetical curve C indicating increased inotropy, to the right toward the hypothetical curve B indicating decreased contractility, or up and down along the hypothetical curve A denoting an unchanged inotropic state (Fig 1). When the relative position of our patients was assessed on the Sarnoff family of curves (Fig 1) it was clear that 72 patients (group I to IV) had enhanced or unchanged RV functions postoperatively. Three patients (group VI) with diminished RV function postoperatively had an uneventful postoperative course.
In conclusion, the findings of this prospective study have shown that in the clinical setting the use of WBRC as the exclusive mode of myocardial protection provides an excellent preservation of the right heart function even among patients with hypertrophied RV and pulmonary hypertension.
|
References
|
|---|
-
Lichtenstein S.V., Ashe K.A., Haysam E.D., Cusimano R.J., Panos A., Slutsky A.S. Warm heart surgery. J Thorac Cardiovasc Surg 1990;101:269-274.[Abstract]
-
Salerno T.A., Houck J.P., Barrozo C.A.M., et al. Retrograde continuous warm blood cardioplegia: a new concept in myocardial protection. Ann Thorac Surg 1991;51:245-247.[Abstract]
-
Aronson S., Lee B.K., Jaroff J.G., et al. Myocardial distribution of cardioplegia solution after retrograde delivery in patients undergoing cardiac surgical procedures. J Thorac Cardiovasc Surg 1993;105:214-221.[Abstract]
-
Winkelmann J., Aronson S., Young C.J., Fernandez A., Lee B.K. Retrograde delivered cardioplegia is not distributed equally to the right ventricular free wall and septum. J Cardiothorac Vasc Anest 1995;9:135-139.[Medline]
-
Christakis G.T., Buth K.J., Weisel R.D., et al. Randomized study of right-ventricular function with intermittent warm or cold cardioplegia. Ann Thorac Surg 1996;61:128-134.[Abstract/Free Full Text]
-
Hayashida N., Ikonomidis J.S., Weisel R.D., et al. The optimal cardioplegic temperature. Ann Thorac Surg 1994;58:961-971.[Abstract]
-
Sarnoff S.J., Berglund E. Starling law of heart studied by means of simultaneous right and left ventricular function curves in dogs. Circulation 1954;9:706-711.[Medline]
-
Shiki K., Masuda M., Yonenaga K., Asou T., Tokunaga K. Myocardial distribution of retrograde flow through the coronary sinus of the excised normal canine heart. Ann Thorac Surg 1986;1:265-271.
-
Menasche P., Kucharski K., Mundler O., et al. Adequate preservation of right ventricular function after coronary sinus cardioplegia. A clinical study. Circulation 1989;80(Suppl III):19-24.
-
Guyton R.A. Warm blood cardioplegia: benefits and risks. Ann Thorac Surg 1993;55:1071-1072.[Medline]
-
Christakis G.T., Koch J.P., Deemar K.A., et al. A randomized study of systemic effects of warm heart surgery. Ann Thorac Surg 1992;54:449-459.[Abstract]
-
Kulshrestha P., Rao L., Garb J.L., Rousou J.A., Engelman R.M., Wait R.B. Use of extrafascially harvested radial artery for coronary artery revascularization: technical considerations. J Card Surg 1999;14:26-31.[Medline]
-
Ross J., Jr Framework for analysis of ventricular function and overall circulatory performance. In: West J.B., ed. Best and Taylor’s physiological basis of medical practice. Baltimore: William & Wilkins, 1985:284-297.
This article has been cited by other articles:
|
|
|
|
 
S. Osaki, N. M. Edwards, M. R. Johnson, and T. Kohmoto
A novel use of the implantable ventricular assist device for isolated right heart failure
Interactive CardioVascular and Thoracic Surgery,
August 1, 2008;
7(4):
651 - 653.
[Abstract]
[Full Text]
[PDF]
|
|
|
|
|
|
|
T. Vahasilta, A. Saraste, V. Kyto, M. Malmberg, J. Kiss, E. Kentala, M. Kallajoki, and T. Savunen
Cardiomyocyte Apoptosis After Antegrade and Retrograde Cardioplegia
Ann. Thorac. Surg.,
December 1, 2005;
80(6):
2229 - 2234.
[Abstract]
[Full Text]
[PDF]
|
|
|
|
|
|
|
H.-Y. Yu, N.-H. Chi, J.-M. Lee, S.-C. Huang, W.-J. Ko, J.-K. Wang, Y.-C. Lee, S.-S. Wang, F.-Y. Lin, and Y.-S. Chen
Rescue of a case of ventricular septal defect with Eisenmenger syndrome using an extracorporeal membrane oxygenator
J. Thorac. Cardiovasc. Surg.,
February 1, 2004;
127(2):
582 - 583.
[Full Text]
[PDF]
|
|
|
Top
Abstract
Introduction
