Antegrade Crystalloid Cardioplegia vs Antegrade/ Retrograde Cold ...

Antegrade Crystalloid Cardioplegia vs Antegrade/ Retrograde Cold and Tepid Blood Cardioplegia in CABG Ahmed M.F. Elwatidy, FRCS, Mohsen A. Fadalah, MD, Emad A. Bukhari, FRCS, Khalid A. Aljubair, FRCS, Aitizazuddin Syed, FRCS, Abullah K. Ashmeg, FRCS, and Mohamed R. Alfagih, FRCS Prince Sultan Cardiac Center, Riyadh, Saudi Arabia

Background. This study evaluated the myocardial protective strategies in isolated coronary bypass surgeries. Methods. One hundred and twenty-eight patients were prospectively randomized to 3 techniques of myocardial protection; group I (n ⴝ 47) antegrade/retrograde tepid blood cardioplegia, group II (n ⴝ 40) antegrade/ retrograde cold blood cardioplegia with topical cooling, group III (n ⴝ 41) antegrade crystalloid cardioplegia with topical cooling. Results. The incidence of spontaneous defibrillation was significantly higher in group I (p < 0.001) while the incidence of low cardiac output was not different between the 3 groups. The incidence of ventricular arrhythmia was higher in group III (p < 0.016 group III vs I). There was no significant statistical difference in hemodynamic recovery between the 3 groups. CK-MB levels

were significantly lower in group I versus the other 2 groups, (p ⴝ 0.0013, 0.04). Acid release and oxygen extraction were higher in group II than in group I (p ⴝ 0.06) during cardioplegia and reperfusion. Lactate release was less in group I at the release of aortic cross-clamp, and reperfusion. There was no significant difference between the 3 groups in ICU stay, ventilation time, or hospital complications. Conclusions. Tepid blood cardioplegia showed superiority in metabolic and functional recovery, whereas crystalloid cardioplegia had the highest incidence of postoperative arrhythmias. There was no significant statistical difference between the 3 groups in hospital mortality and morbidity. (Ann Thorac Surg 1999;68:447–53) © 1999 by The Society of Thoracic Surgeons

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the myocardium, have slowed its adoption in many centers. A proposed solution to overcome the limitations of antegrade and retrograde cardioplegia was the use of a combined antegrade and retrograde infusions, which was suggested by Weisel and associates in 1994 [7]. Tepid “lukewarm” (28 –32°C) cardioplegia was introduced after that to avoid the potential hazards associated with normothermic “warm” or hypothermic cardioplegic temperatures.

he multiplicity of cardioplegic solutions available, their method of delivery, patient selection, and the methods used to determine myocardial injury have made it difficult to accurately determine which form of cardioplegia is best [1]. There is some clinical evidence, however, that blood cardioplegia provides better myocardial protection in certain subsets of high-risk patients [2]. The concept of warm cardioplegic induction was introduced in 1983, based on the realization that induction of cardioplegia in the ischemically damaged, energy and substrate-depleted heart is really the first phase of reperfusion [3]. This approach attempts to maximize the kinetics of repair, and minimize O2 demands by maintaining arrest. Experimental and subsequent clinical data showed that warm induction could actively resuscitate the heart and improve its tolerance to the subsequent interval of cold ischemia imposed for technical reasons [4, 5]. Using the retrograde technique, Panos and colleagues [6] in Toronto began experimenting with warm continuous cardioplegia in 1989, and reported their results in 1990. Potential technical problems with the technique, along with lack of safe metabolic monitoring for Accepted for publication Feb 24, 1999 Address reprint requests to Dr Elwatidy, Medical College of Virginia, Virginia Commonwealth University, Richmond, VA 23298-0532; e-mail: [email protected].

© 1999 by The Society of Thoracic Surgeons Published by Elsevier Science Inc

Material and Methods An institutional review committee approved the study and informed consent was obtained prior to enrolling patients in the study. One hundred and twenty-eight patients underwent coronary artery bypass grafting (CABG) with the same surgical technique and were prospectively randomized to receive 1 of 3 different strategies of myocardial preservation; group I: antegrade/retrograde tepid blood cardioplegia (n ⫽ 47); group II: antegrade/retrograde cold blood cardioplegia with topical cooling (n ⫽ 40); group III: antegrade crystalloid cardioplegia with topical cooling (n ⫽ 41). Redo CABG and CABG with other procedures were excluded from the study. Preoperative demographic data and risk factors are shown in Tables 1 and 2. 0003-4975/99/$20.00 PII S0003-4975(99)00359-8

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ELWATIDY ET AL MYOCARDIAL MANAGEMENT IN CABG

Ann Thorac Surg 1999;68:447–53

Table 1. Demographic Data of the Study Groups Group I (n ⫽ 47)

Group II (n ⫽ 40)

Demographic Data

n

%

Age (years) Sex (% of female) Weight (kg) Preoperative cardiovascular intervention Preoperative MI (old/recent) Past history of CHF Hypertension Diabetes Smoking Family history of CAD Dyslipidemia Renal impairment Cerebrovascular accident

57.4 ⫾ 9.2 10.60 73.4 ⫾ 1.6 11 23.40

n

29/2 3 20 19 22 9 22 3 0

61.7/4.25 6.30 42.6 40.42 46.8 19.4 46.8 6.38 0

%

57.9 ⫾ 9.2 8 20 70.6 ⫾ 1.4 7 17.5

5

Group III (n ⫽ 41) n

Total (n ⫽ 128)

%

n

57.04 ⫾ 10 9.8 75.6 ⫾ 2 11 20

%

p Value

57.4 ⫾ 9.4 13.3 73.2 ⫾ 1.6 29 22.6

4

NS NS NS NS

17

31/0

77.5/0

23/2

56.1/4.88

83/4

64.8/3.1

NS

0 24 18 15 7 15 1 0

0 53.7 45 37.5 17.5 37.5 2.5 0

1 22 19 21 10 16 3 2

2.44 60 46.3 51.22 23.4 39.02 7.3 4.87

4 66 56 58 26 53 7 2

3.1 51.6 44 45 20 41 5 1.6

NS NS NS NS NS NS NS NS

CAD ⫽ coronary artery disease; CHF ⫽ congestive heart failure; Group I ⫽ antegrade/retrograde tepid blood cardioplegia; Group II ⫽ antegrade/retrograde cold blood cardioplegia; Group III ⫽ antegrade crystalloid cardioplegia with topical cooling; MI ⫽ myocardial infarction; NS ⫽ statistically non-significant.

Operative Technique

on cross-clamp, and the top-end anastomoses were fashioned to the aorta on a side-biting aortic clamp.

Swan Ganz catheter was inserted routinely for all patients. Standard median sternotomy, full heparinization, aortic and two-stage venous cannula were inserted. Antegrade cardioplegia and venting were accomplished through another aortic cannula. A retrograde coronary sinus cannula (DLP with self-inflatable balloon; Grand Rapids, MI) was inserted routinely in group I & II using blind insertion technique. Standard cardiopulmonary bypass (CPB) and moderate systemic hypothermia (25– 28°C) were instituted for all patients. All the distal-end anastomoses were fashioned with continuous 7/0 proline

Preparation of Cardioplegic Solution Modified Roe’s solution was the crystalloid cardioplegic solution used at 4°C, in the following composition (per 500 mL dextrose 5%); sodium Chloride 13.5 mEq, potassium Chloride10 mEq, magnesium sulfate 1.5 mEq, sodium bicarbonate (8.4% solution) 1.1 mEq, methyl prednisilon 125 mg. The solution is delivered, keeping an average aortic root pressure around 60 –90 mm Hg and a flow rate at

CRYSTALLOID CARDIOPLEGIA.

Table 2. Demographic Data of the Study Groups Group I (n ⫽ 47) Demographic Data Average CCS class Unstable angina NYHA class Preoperative arrhythmia Poor LVF (EF ⱕ 30%) Mean EF1 No. of preoperative medication Elective Emergency LMS (⬎ 40%) Number of diseased vessels Mild/moderate/severe CAD Proximal/distal anastomosis LIMA/BIMA/endarterectomy

n

%

3.34 ⫾ 0.52 18 38.3 2.1 ⫾ 0.6 2 4.2 4 8.5 45.85 ⫾ 8.62 3.78 ⫾ 1.4 31 66 6 12.6 18 38.3 2.72 ⫾ 0.54 7/28/12 15/60/25 1.91/3.0 45/6/2 96/13/4

Group II (n ⫽ 40) n

%

3.2 ⫾ 0.56 11 27.5 1.9 ⫾ 0.54 2/40 5 1 2.5 46.5 ⫾ 7.78 4.55 ⫾ 1.2 27 67.5 1 2.5 5 12.5 2.85 ⫾ 0.43 4/29/7 10/72/18 2.21/3.02 36/1/0 90/2.5/0

Group III (n ⫽ 41) n

%

3.2 ⫾ 0.47 10 24.4 2.07 ⫾ 0.56 3 7.2 2 4.9 49.23 ⫾ 9.43 3.85 ⫾ 1.6 32 78.1 7 17.1 16 39 2.82 ⫾ 0.44 2/27/12 5/66/29 1.93/2.78 35/1/1 85/2.4/2.4

Total (n ⫽ 128) n

%

3.25 ⫾ 0.51 39 29.7 2.02 ⫾ 0.56 7 5.5 7 5.5 47.2 ⫾ 8.6 4.06 ⫾ 1.4 90 70.3 14 11 39 30.5 2.8 ⫾ 0.5 13/84/31 10/66/24 2.01/2.93 116/8/3 91/6/2

p Value NS NS NS NS NS NS 0.01a NS NS 0.01a NS NS NS NS

statistically significant (p ⬍ 0.5). BIMA ⫽ bilateral internal mammary artery; CAD ⫽ coronary artery disease; CCS ⫽ canadian cardiovascular LIMA ⫽ left internal mammary artery; LMS ⫽ left main stem stenosis; NS classification of angina; EF1 ⫽ preoperative ejection fraction; ⫽ not significant; NYHA ⫽ New York Heart Association functional classification. Group I ⫽ antegrade/retrograde tepid blood cardioplegia; Group II ⫽ antegrade/retrograde cold blood cardioplegia; Group III ⫽ antegrade cystalloid cardioplegia with topical cooling. a


175–200 mL/min. One liter of crystalloid cardioplegic solution was given initially and a booster injection (250 –350 cc) was delivered after each distal-end anastomosis. Topical cold saline was applied repeatedly around the heart. BLOOD CARDIOPLEGIA. Blood cardioplegia was delivered (via a ratio of 4:1) by an Avecor Myotherm Cardioplegia System (Model 41, 41-B). One liter of warm blood cardioplegia (37°C) with high potassium (16 mEq/L) was initially given antegrade (warm induction-high K⫹) then shifted to the retrograde route while the distal-end anastomosis was fashioned, at a rate of 250 –300 mL/min, keeping the coronary sinus pressure around 40 mm Hg. This method, interrupted only if the surgical exposure is difficult, is called semicontinuous tepid (28 –30°C) cardioplegia with low-K⫹ (8mEq/L). One liter of warm (37°C) cardioplegia was given retrograde before declamping the aorta (hotshot). Cold blood cardioplegia technique (at 8°C) is started with 1 L high-K⫹ (no warm induction) after cross-clamping followed by intermittent (every 15–20 minutes) retrograde (low-K⫹) cold blood cardioplegia (500 –750 mLs). A hot shot was also given.

Coronary Sinus Sampling Coronary sinus sampling was done in groups I and II (blood cardioplegia) to measure lactate extraction, acid release and oxygen extraction. This was done before cross-clamping, just prior to the hot shot, immediately and 10 min after the cross-clamp release, and 10 min after fashioning all top-end anastomoses. Samples were taken simultaneously from the arterial or cardioplegia line. Blood samples were analyzed for PO2, PCO2, O2 saturation, O2 content, pH, Serum Base Excess (SBE), and Hb. The temperature difference was taken into consideration and corrected during calculation. The following formulas were used to calculate O2 extraction, lactate and acid release [8]: O2 content ⫽ 1.39 Hb x O2 saturation ⫹ 0.0031 PO2; myocardial O2 extraction ⫽ O2 content of blood cardioplegia or arterial blood ⫺ O2 content of coronary sinus (CS) blood; myocardial lactate extraction ⫽ blood cardioplegia lactate content ⫺ CS lactate content; acid production ⫽ coronary venous [H⫹] ⫺ cardioplegia [H⫹] or arterial [H⫹]; total myocardial O2 extraction, acid release, or lactate release ⫽ cardioplegia flow (mL/min) x difference in content; acid concentration [H⫹] ⫽ antilog. (⫺pH).

Observation in the OR and ICU The incidence of spontaneous defibrillation, incidence of low cardiac output (CP) (defined as: unusual need of inotropic (⬎ 6U dopamine) or mechanical (IABP or VAD) support to maintain the normal CO of the patient (normal CO 4 – 8 L/min and CI 2.54 L/min/m2). Incidence of significant postoperative arrhythmia (any new arrhythmia required treatment), and the need for temporary pacing were also recorded.

Hemodynamic Assessment Hemodynamic parameters included heart rate (HR), mean arterial blood pressure (MAP), mean central ve-


449

nous pressure (CVP), mean pulmonary artery pressure (mPAP), mean pulmonary capillary wedge pressure (PCWP), cardiac output, cardiac index (CI), stroke index (SI), Right and left ventricular stroke work indices (RVSWI, LVSWI). These parameters were recorded before CPB, and 1, 6, 12, and 24 hours after CPB. CO was measured in triplicate by using the thermodilution technique. A computerized calculation of the other parameters was automatically provided, based on body weight, height, surface area and filling pressures. A standard protocol was followed for volume replacement before hemodynamic measurements were taken.

Creatine Kinase Blood samples were taken for total creatine kinase (CK) and its myocardial band, CKCK-MB (MB) at 1, 6, 12, 24, and 48 hours after arrival to the ICU.

Statistical Analysis All data were entered on the SPSS statistical analysis program (Release 6.1.3, August 24, 1995) for Windows. One way and multiple analysis of variation (ANOVA) F-tests were used to compare the 3 groups. When ANOVA indicated a significant difference between the groups of cardioplegia (p ⬍ 0.05), post-hoc multiple comparison tests were applied. (eg, Bonferroni, Ducan’s, Student-Newman Keul’s test).

Results Analysis of preoperative demographic data and risk factors showed some statistical differences between the 3 groups in the incidence of significant left main stenosis (LMS ⱖ 40%), and in the number of preoperative medications. The average bypass time was 110.7⫾28 minutes, with no statistical difference between the 3 groups. The average cross-clamp time was longer in group I (74.9⫾17.9 minutes), than in groups III (69.1⫾22.8 minutes) and II (62.9⫾17.1 minutes) respectively (p ⫽ 0.002 and 0.02). Univariate and multivariate analysis showed no change in the results of response to a higher incidence of LMS or the longer cross-clamp time shown above groups. There was no significant statistical difference between the 3 groups in the average number of proximal or distal anastomoses, use of left internal mammary artery (LIMA), bilateral internal mammary artery (BIMA), or endarterectomy. The incidence of spontaneous defibrillation was significantly higher in group I than in group II or III (p ⬍ 0.001). The overall incidence of low CO in this study was 9.4% and was higher in group II (15%) and group III (7.2%) than in group I (6.3%). The average postoperative ejection fraction (EF) was 47.8⫾9 with no significant difference between the 3 groups. The total incidence of postoperative arrhythmias, as well as the use of antiarrhythmic drugs, was higher in group III compared to groups I and II, but was statistically insignificant (p ⫽ 0.08). There was a statistical difference between groups I and III in ventricular arrhythmia (p ⫽ 0.016) (Table 3). Perioperative myocardial infarction (first 48 hours post-

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Table 3. Operative and Postoperative Data Group I (n ⫽ 47) n

Bypass time Cross-clamp time

112.26 ⫾ 24.2 74.96 ⫾ 17.9

114.5 ⫾ 30.3 62.96 ⫾ 17.1

105.41 ⫾ 29.6 69.17 ⫾ 22.8

Spontaneous defibrillation

45

95.7

1

2.5

6

14.6

52

40.6

4

8.4

9

22.5

5

12.2

18

14

4.2/2.1 0 6.3 14.7

1/2 0 6 5

2 1 4 1/0 0

4.2 2.1 8.4 2.1/0 0

1 3 1 0/0 0

2.5/5 0 15 12.5 2.5 7.5 2.5 0/0 0

n

%

Total (n ⫽ 128)

n

2/1 0 3 7

%

Group III (n ⫽ 41)

Variable

Use of significant inotropic support IABP preop/postop Use of VAD Incidence of low CO Postop arrhythmia (total incidence) Atrial (A) Ventricular (V) A⫹V MI (periop/postop) Postoperative angina

%

Group II (n ⫽ 40)

n

% 110.7 ⫾ 28 69.03 ⫾ 19.2

p Value NS Group II vs III, p ⫽ 0.02 Group I vs II, p ⫽ 0.002 Group I vs II, p ⬍ 0.001 Group I vs III, p ⬍ 0.001 Group II vs III, p ⬍ 0.001 NS

1/1 0 3 12

2.4/2.4 0 7.2 29.3

4/4 0 12 24

3.1/3.1 0 9.4 18.7

NS NS NS NS

1 6 5 1/0 1

2.4 14.6 12.2 2.4/0 2.4

4 10 10 2/0 1

3.13 7.8 7.8 1.6/0 0.8

NS Group I vs III, p ⫽ 0.016 NS NS NS

Group I ⫽ antegrade/cetrograde tepid blood cardioplegia; Group II ⫽ antegrade/retrograde cold blood cardioplegia; Group III ⫽ antegrade crystalloid cardioplegia with topical cooling; IABP ⫽ intraaortic balloon pump; low CO ⫽ low cardiac output; MI ⫽ myocardial infarction; NS ⫽ not statistically significant; VAD ⫽ ventricular assist device.

operatively) was defined in this study as the appearance of new Q wave in more than one pericordial lead or ischemic ST segment changes associated with concomitant rise of CKCK-MB (MB) levels. There were 2 patients who had perioperative MI; 1 patient in group I and another in group III. One patient had postoperative MI (following the first postoperative 48 hours) and another had postoperative angina. No significant statistical differences were found in the above factors. The average hospital stay was11.13⫾6.9 days, ICU stay 37.8⫾21 hours, and ventilation time 13.8⫾10.4 hours. There was no statistical difference between the 3 groups. There was no statistical difference between the 3 groups in postoperative medications, hospital complications and mortality. Serum enzyme levels were significantly higher in group III than in the other 2 groups (Fig 1). Generally there was no significant statistical difference in the hemodynamic performance between the 3 groups. The heart rate generally increased from an average of 74⫾14 beats/min to 92⫾9 beats/mint (p ⬍ 0.001). The average RVSWI before surgery was 13.5⫾4.2 g m/m2 compared to 14.8⫾3.1 g m/m2 after surgery. The corresponding filling pressures before and after surgery were respectively (CVP 6.2⫾2.3 mm Hg compared to 9.2⫾1.5 mm Hg after surgery (p ⬍ 0.03) and mPAP 15.1⫾9.3 mm Hg compared to 17.1⫾2.1 mm Hg after surgery (p ⫽ 0.8). The average LVSWI before surgery was 54.5⫾24.6 g m/m2 compared to 54.64⫾12.4 g m/m2 after surgery (p ⬍ 0.02). The corresponding filling pressures before and after surgery were respectively; PCWP 8.5⫾2.1 mm Hg compared to 10.8⫾1.7 mm Hg after

surgery (p ⬍ 0.001) and mABP 77.6⫾6.8 mm Hg compared to 82.6⫾9.4 mm Hg after surgery (Fig 2). The oxygen extraction was less with tepid than cold blood cardioplegia on cross-clamp before giving the warm shot (p ⫽ 0.08) which was associated with less acid release (p ⫽ 0.05) and a slight increase in lactate production. During reperfusion, the lactate and acid washouts were much less in group I than in group II. Myocardial oxygen extraction was less after 10 minutes of reperfusion in group I versus group II. However, oxygen extraction tends to be similar in both groups after top-end anastomoses (Fig 3).

Fig 1. Postoperative CKCK-MB (MB) levels.



451

Fig 2. Postoperative stroke index (SI), right ventricular stroke work index (RVSWI), and left ventricular stroke work index (LVSWI).

Comment Spontaneous resumption of rhythm has been used by many surgeons as an indicator of myocardial recovery after a period of cross-clamping which could reflect to some extent the state of myocardial protection [9 –13]. Lichtenstein and associates [11, 12, 14] reported a 99% rate of spontaneous defibrillation in continuous warm blood cardioplegia compared with 10% in antegrade cold blood cardioplegia with topical cooling. Molina and coworkers [13] reported a 96% incidence of spontaneous defibrillation, a figure considerably greater than the 60% reported by Lolly and colleagues [15] using anaerobic substrate enhancement using glucose solutions containing insulin and potassium (GIK). Both results correlate with ours. The incidence of low CO in our study was lower in group I than in the other two groups, although statistically insignificant. Lichtenstein and associates [11, 12] reported a lower incidence of low CO (6.3%) in continuous warm antegrade blood cardioplegia in primary isolated CABG, than intermittent cold antegrade blood cardioplegia (14%); and the need for IABP support was zero in the warm groups versus 12.5% in the cold group. Yau and associates [16] compared 5 different techniques of myocardial protection in primary isolated CABG. They found that the incidence of low CO tended to be higher after warm retrograde or intermittent cold cardioplegia, but this difference was not statistically significant. The requirement for postoperative IABP support was also higher in warm retrograde cardioplegia. Warm retrograde cardioplegia proved to be an insufficient technique, if used alone for myocardial protection, due to the proven defective perfusion. Its important value was proven clear when used as a complementary technique to the antegrade route. Hayashida and colleagues [17] compared 3 groups of patients (42 patients); antegrade/ retrograde cold (9°C), warm (37°C), and tepid (29°C) blood cardioplegia. None of the patients had low output syndrome or required an intraaortic balloon pump postoperatively. Many surgeons have studied the incidence of postoperative arrhythmias in relation to the myocardial protection technique. Chen and associates [18] have

Fig 3. (A) O2 Extraction, (B) Acid Release, and (C) Lactate Extraction.

proven the superiority of antegrade cold blood cardioplegia with topical cooling over the antegrade crystalloid cardioplegia in prevention of supraventricular arrhythmias and conduction disturbances (5.8% compared with 21.4%; (p ⫽ 0.013). Louagie and associates [19] reported a higher incidence of supraventricular arrhythmias in the retrograde continuous cold blood cardioplegia group (19.6%). When the temperature was raised from 8°C to 18°C in this group particularly, the incidence rose from 19.6% to 34.2% (p ⫽ 0.009). Ventricular arrhythmias were higher in the continuous retrograde (3.6%) and lower (1.1%) in the intermittent retrograde. These results suggested that cardioplegia temperature, rather than administration rate (continuous or intermittent), could influence the occurrence of supraventricular arrhythmias. Beyersdorf and associates [20] reported a lower incidence of rhythm disturbances in multidose antegrade cold blood cardioplegia (17%). Our results correlate with both Chen’s and Beyersdorf’s results, that cold cardioplegia groups (crystalloid and blood) were having an overall lower incidence of atrial arrhythmias and that can ex-

452


plain Louagie’s results which suggested that temperature of the cardioplegic solution was a determinant factor for supraventricular arrhythmia. Perioperative MI occurred in 2 patients (1.6%) in the study. Louagie and associates [19] reported higher incidence of perioperative MI in continuous retrograde cold blood cardioplegia (6.3%), than intermittent cold retrograde blood (2.3%) and intermittent antegrade cold blood cardioplegia (1%); though there was no significant statistical difference between the 3 groups. Hayashida and associates [17] reported 2.3% incidence of perioperative MI in the cold antegrade/ retrograde blood cardioplegia group compared to both warm and tepid antegrade/retrograde blood cardioplegia. Again, there was no significant statistical difference between the 3 groups. In a series of 107 patients undergoing isolated CABG, Yau and associates [16] reported 3 patients with perioperative MI (2.8%), with no statistical significance between 5 techniques of blood cardioplegia. Ventilation time, ICU stay, and hospital stay have been causing more concern during the last few years when used as a trial to reduce hospital cost and improve patients recovery at the same time [21]. There was no significant statistical difference between the 3 groups in any of the 3 factors. In this study, there was a general trend toward better myocardial recovery in group I versus the other 2 groups, though statistically insignificant. Hayashida and colleagues [17] reported that LVSWI were greater after tepid cardioplegia (36⫾2 g m/m2) versus cold (25⫾2 g m/m2) or warm cardioplegia (26⫾2g m/m2), 4 hours after off bypass despite similar filling pressures (PAP & PCWP). Tepid cardioplegia had greater myocardial performance by an analysis of covariance (p ⫽ 0.0001). There was no difference in the RVSWI or right atrial pressure between the 3 groups. Louagie and associates [19] showed that both LVSWI and RVSWI were markedly higher in the continuos retrograde cold (8°C) blood cardioplegia, compared with intermittent antegrade or retrograde cold blood cardioplegia groups. The activity of CKCK-MB (MB) is the most widely used isoenzyme marker for myocardial infarction and ischemic injury because of its greater cardio-specificity [9]. The average CKCK-MB (MB) levels were significantly lower in group I, especially at 1, 6, and 24 hours after arrival to the ICU. In this study, it is worth mentioning that there was a positive correlation between the higher levels of CKCK-MB (MB) and the higher incidence of postoperative arrhythmias (r ⫽ 0.25, p ⫽ 0.03) in group III, which may explain a transient or recoverable insult to the myocardium. Yau’s and Louagie’s studies [17, 19] demonstrate that the intermittent cold retrograde blood cardioplegia alone has the highest CKCK-MB (MB) levels, which could also be explained on the basis of defective myocardial perfusion and protection by this technique alone. In our study, the retrograde route was used as complementary to the antegrade in both cold and tepid blood groups, and the superiority of tepid group was well demonstrated. Studying the myocardial metabolic activity during cardioplegia and reperfusion has gained much interest since the introduction of cardioplegia. Our results prove that tepid blood cardioplegia has superior myocardial meta-


bolic protection and recovery compared the intermittent cold blood group. It is also clear that the terminal hot shot is not as effective in the cold group as it is in the tepid blood group. Hayashida and colleagues [17] demonstrated that tepid cardioplegia produced similar myocardial oxygen consumption to warm cardioplegia during cardioplegic arrest suggesting preservation of mitochondrial function. He mentioned that tepid cardioplegia reduced anaerobic lactate release compared with warm cardioplegia. Though myocardial oxygen consumption was greater with warm or tepid than cold, anaerobic lactate and acid washout were less with tepid or cold than warm blood cardioplegia. Lactate and acid washout were least after tepid and greatest after warm at the time of cross-clamp release. Their findings suggested that the combination of intermittent antegrade and continuous retrograde tepid cardioplegia provided superior myocardial protection when coronary obstruction or interruptions limited cardioplegia delivery. Postoperative hospital complications included sternal exploration for bleeding, large pericardial effusion or tamponade (6.25%), wound problems (4.7%), neurological (3.9%), pulmonary (5.5%), vascular (0%) especially with IABP, renal (0.8%), and gastrointestinal tract (GIT) complications (1.6%). Hayashida and associates [17] reported no significant difference between the 3 groups in postoperative complications. Yau and associates [16] reported no significant difference in hospital complications between 5 groups of blood cardioplegia. Lichtenstein and associates [11, 12] reported a decreased operative mortality rate from 2.2% to 0.9% when antegrade normothermic blood cardioplegia was compared with antegrade cold blood cardioplegia. This decrease in mortality was not significant between the 2 groups. In conclusion, our study showed that: (1) Tepid blood cardioplegia showed superiority in both metabolic and functional recovery. (2) Intermittent antegrade crystalloid cardioplegia with topical cooling had a high incidence of postoperative arrhythmia especially ventricular arrhythmias. (3) There was no significant statistical difference between the three groups in hospital mortality and morbidity. The authors express their gratitude to all the members of the anaesthesia department, perfusion team, and to the great help of Mohamed Yousef and Catherine McGeoch, at Prince Sultan Cardiac Center, for their support in this study.

References 1. Ebert PA. Aspects of myocardial protection [Editorial]. Ann Thorac Surg 1978;26:495– 6. 2. Follette DM, Mulder DG, Maloney JV Jr, 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 3. Rosenkranz ER, Okamoto F, Buckberg GD, Robertson JM, Vinten-Johansen J, Bugyi H. Safety of prolonged aortic clamping with blood cardioplegia. III. Aspartate enrichment of glutamate-blood cardioplegia in energy-depleted hearts after ischemic and reperfusion injury. J Thorac Cardiovasc Surg 1986;91:428–35.


4. Rosenkranz ER, Buckberg GD. Myocardial protection during surgical coronary reperfusion. J Am Coll Cardiol 1983;1: 1235– 46. 5. Buckberg GD. Update on current techniques of myocardial protection. Ann Thorac Surg 1995;60:805–14. 6. Panos A, Abel J, Slutsky AS, Salerno TA, Lichtenstein SV. Warm aerobic arrest: a new approach to myocardial protection [Abstract]. J Mol Cell Cardiol 1990;22(Suppl 5):531. 7. Weisel RD, John SI, Rao V, et al. Myocardial protection for coronary bypass grafting: the Toronto Hospital perspective. Ann Thorac Surg 1995;60:824–32. 8. Hayashida N, Ivanov JRN, Carson SM, et al. Tepid antegrade and retrograde cardioplegia. Ann Thorac Surg 1995;59:723–9. 9. Hearse DJ. Assessment of myocardial protection. In: Hearse DJ, Brinbridge MV, eds. Protection of the ischemic myocardium. New York: Raven Press, 1981:312–35. 10. Michael C, Mauney MC, Kron IL. The physiologic basis of warm cardioplegia. Ann Thorac Surg 1995;60:819–23. 11. Lichtenstein SV, El Dalati H, Panos A, Slutsky AS. Long cross-clamp times with warm heart surgery [Letter]. Lancet 1989;1:1443. 12. Lichtenstein SV, Ashe KA, El Dalati H, Cusimao RJ, Slutsky AS. Warm heart surgery. J Thorac Cardiovasc Surg 1991;101: 269–74. 13. Molina JE, Feiber W, Sisk A, Polen T, Collins B. Cardioplegia without fibrillation or defibrillation in cardiac surgery. Surgery 1977;81:619–26. 14. Craver JM, Sams AB, Hatcher CR. Potassium-induced car-


15.

16. 17. 18.

19. 20.

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dioplegia: additive protection against ischemic myocardial injury during coronary revascularization. J Thorac Cardiovasc Surg 1978;76:24–7. Lolley DM, Ray JF, Myers WO, Sheldon G, Sautter RD. Reduction of intraoperative myocardial infarction by means of anaerobic substrate enhancement: Prospective randomized study. Ann Thorac Surg 1978;26:515–23. Yau TM, John SI, Weisel RD, et al. Which techniques of cardioplegia prevent ischemia? Ann Thorac Surg 1993;56: 1020– 8. Hayashida N, Ivanov JN, Carson SM, et al. Tepid antegrade and retrograde cardioplegia. Ann Thorac Surg 1995;59:723–9. Chen YF, Kao HK, Lin YT, et al. The superiority of blood over electrolyte cardioplegia in prevention of supraventricular arrhythmias and conduction disturbances following openheart surgery. Kao Hsiung I Hsueh Ko Hsueh Tsa Chih 1989;5:548 –55. Louagie YA, Gonzalez E, Jmart J, et al. Assessment of continuous cold cardioplegia in coronary artery bypass grafting. Ann Thorac Surg 1997;63:689–96. Beyersdorf F, Krause E, Sarai K, et al. Clinical evaluation of hypothermic ventricular fibrillation: multi-dose blood cardioplegia, and single-dose Bretschneider cardiopleplegia in coronary surgery. Thorac Cardiovasc Surg 1990;38:20 –9 Loop FD, Higgins TL, Panda R, et al. Myocardial protection during cardiac operations. J Thorac Cardiovasc Surg 1992; 104:608–18.

Discussion Groups on the Internet The following three articles will be published in the September 1999 issue of The Annals of Thoracic Surgery, and have been selected for discussion topics on the Internet. These discussion groups can be accessed by going to the Society of Thoracic Surgeons Home Page (http://www.sts.org) and clicking on “Discussion Forums.” We encourage everyone to participate, as our goal is to make the discussion as interactive as possible.

Initial Experience With the Radial Incision Approach for Atrial Fibrillation Takashi Nitta, MD, Yosuke Ishii, MD, Hidetsugu Ogasawara, MD, Shunichiro Sakamoto, MD, Yasuto Miyagi, MD, Kenichi Yamada, MD, Shigeto Kanno, MD, and Shigeo Tanaka, MD, PhD Tracheal Allograft Reconstruction: The Total North American and Worldwide Pediatric Experiences

Sleeve Resection and Prosthetic Reconstruction of the Pulmonary Artery for Lung Cancer

Jeffrey P. Jacobs, MD, James A. Quintessenza, MD, Tom Andrews, MD, Redmond P. Burke, MD, Zorik Spektor, MD, Ralph E. Delius, MD, Richard J.H. Smith, MD, Martin J. Elliott, MD, FRCS, and Claus Herberhold, MD

Enrico A. Rendina, MD, Federico Venuta, MD, Tiziano De Giacomo, MD, Anna Maria Ciccone, MD, Marco Moretti, MD, Giovanni Ruvolo, MD, and Giorgio Furio Coloni, MD

Tom R. Karl, MD Internet Annals Editor Melbourne, Australia e-mail: [email protected].

© 1999 by The Society of Thoracic Surgeons Published by Elsevier Science Inc

Ann Thorac Surg 1999;68:453 • 0003-4975/99/$20.00 PII S0003-4975(99)00359-8