Intermittent Aortic Cross-clamping Research Articles

Does Intermittent Aortic Cross Clamping Decrease the Incidence of Atrial Fibrillation after Coronary Bypass Surgery?

Atrial fibrillation (AF) is the most common arrhythmia after coronary artery bypass grafting (CABG). AF is a vexing problem that causes morbidity, prolongs hospital stay, and increases costs. Numerous factors have been suggested to play a role in the development of AF. The aim of this study was to evaluate the effect of intermittent aortic cross clamping (IACC) compared with hypothermic cardioplegic solution (HCS) in the development of postoperative AF. We evaluated data obtained from 345 patients undergoing CABG with HCS (HCS group, n = 212) and IACC (IACC group, n = 173) between April 2004 and August 2005. Diabetes mellitus was observed more often in the HCS group (P < .05), otherwise both groups had similar preoperative characteristics including sex, age, the number of distal anastomoses, left ventricle ejection fraction, history of myocardial infarction, and use of beta-blocker medication. The only statistically significant difference between the groups was higher postoperative Ca-antagonist use in the HCS group. Rates of postoperative AF, however, were significantly lower in the IACC group (21.52%) than that in the HCS group (11.05%; P < .01). Postoperative Ca-antagonist use in the HCS group and smoking in the IACC group were independent predictors of AF after CABG. The incidence of postoperative AF after CABG with IACC was reduced compared with HCS. IACC with ventricular fibrillation may exert a counteractive effect against AF.

Intermittent aortic cross-clamping for isolated CABG can save lives and money: experience with 15307 patients.

The ideal myocardial protection during isolated CABG is still a matter of debate. Cardioplegia versus intermittent aortic cross-clamping (IACC) are the main opponents; the following article shows that IACC can be safe, efficient and might be cheaper than cardioplegia. Demographics and co-morbidities of 15307 CABG only patients consecutively operated on between January 1993 and October 2001 in the Heart Center in Bad Oeynhausen were assessed by the German Quality Assurance data set and risk-stratified using the EuroSCORE. Outcome (30-day or in-hospital mortality) was compared to the expected EuroSCORE estimation. Expected mortality was 3.25 %, observed mortality was 1.3 %, being significantly lower in the low, medium as well as high risk patients subgroup. Complication rates increased steadily with expected mortality rates. Stroke and myocardial infarction rates for patients with peripheral vessel disease were not higher than in comparable studies. More than 1000000 EUR were saved by lower cardioplegia bills. Myocardial protection with intermittent aortic cross-clamping for isolated CABG can be safe, effective, and economically advantageous when compared to cardioplegic solutions.

Myocardial protection for repeat coronary artery operations: Comparison of cold crystalloid cardioplegic arrest vs. intermittent aortic cross-clamping

Myocardial protection for repeat coronary artery operations: Comparison of cold crystalloid cardioplegic arrest vs. intermittent aortic cross-clamping

Abstracts

Abstracts

Noncardioplegic surgery for ischemic mitral regurgitation.

Twenty-seven consecutive patients underwent surgery for ischemic mitral regurgitation (MR): papillary muscle rupture (1), papillary muscle dysfunction (11) and annular dilatation (15). The grade of MR was moderate or severe, and the ejection fraction (EF) was less than 30% in 8 patients (mean, 43%). Three cases were reoperation and 3 were emergencies. Under ventricular fibrillation (VF) and intermittent aortic cross-clamping at moderate hypothermia, coronary artery bypass grafting (CABG) was performed first, followed by the mitral procedure through a right-sided left atriotomy (repair 21, replacement 6) performed under VF with the heart perfused through the native coronary arteries and CABG grafts. Concomitant procedures were CABG (23), Dor's procedure (5), and tricuspid annuloplasty (3). In one reoperative case with cardiogenic shock, CABG was impossible because of dense adhesions and the patient died just after surgery (hospital mortality, 3.7%). Five patients required intra-aortic balloon pump (IABP) support intraoperatively, but none required prolonged (> or =7 days) inotropic support or IABP use, although the serum concentrations of creatine kinase and its myocardial fraction were elevated remarkably. Other morbid events were refractory ventricular arrhythmia in one case and stroke in another. Median duration of mechanical ventilation and intensive care unit stay was 8 h and 3 days, respectively. Mean EF at hospital discharge was 48%. The extended period of VF was not associated with unfavorable clinical outcomes. Noncardioplegic surgery for ischemic MR was carried out with acceptable mortality and morbidity, and can be a good alternative, especially when clamping the aorta is undesirable.

Isolated myocardial revascularization with intermittent aortic cross-clamping: experience with 800 cases

Background. We investigated the clinical outcome of elective and nonelective myocardial revascularization performed with intermittent aortic cross-clamping. Methods. Prospective data on 800 consecutive patients (from May 1996 to July 2000), who underwent isolated myocardial revascularization with intermittent aortic cross-clamping, were analyzed. A subgroup analysis was performed on the elective (n = 520), urgent (n = 226), and emergency (n = 54) procedures. Results. The elective group of patients had a mean age of 61.5 ± 9.46 years, mean Parsonnet score of 5.23 ± 5.1, and mean number of distal anastomoses of 3.22 ± 1.04. The hospital mortality was 0.57%. The urgent group of patients had a mean age of 63.06 ± 10.43 years, mean Parsonnet score of 6.73 ± 6.22, and mean number of distal anastomoses of 3.21 ± 1.04. The hospital mortality was 3.09%. The emergency group of patients had a mean age of 63.75 ± 9.63 years, mean Parsonnet score of 11.24 ± 11, and mean number of distal anastomoses of 2.87 ± 0.86. Hospital mortality was 5.55%. Postoperative hospital stay was 7.11 ± 5.47 days for the elective group, 7.59 ± 5.07 days for the urgent group, and 7.40 ± 4.01 days for the emergency group. Conclusions. Intermittent aortic cross-clamping is a safe technique both in elective and nonelective patients. The mortality and morbidity in the three subgroups analyzed reflects patients’ distribution against Parsonnet score.

Noncardioplegic myocardial protection in high-risk coronary artery bypass grafting

This study was undertaken to determine whether intermittent aortic cross-clamping in the fibrillating heart can be used successfully in high-risk coronary artery bypass grafting.

Atrial natriuretic peptide as an indicator of mild postoperative cardiac dysfunction after uncomplicated bypass surgery

Plasma levels of ANP (pg/ml; radioimmunoassay) as a parameter for postischemic dysfunction and levels of Troponin T (TnT) (ng/ml; ELISA test) as a parameter for postischemic cellular damage were determined in 15 patients with coronary artery disease (CAD) (mean age: 58 +/- 6.1 years; 13 m, 2 w; with no history of myocardial infarction and no signs for congestive heart failure) prior to, during and after extracorporal circulation (ECC). Under standardized conditions during the ECC basic parameters concerning the cardial hemodynamic (heart rate (HR); systolic (RRsys, mmHg), diastolic pressure (RR dia, mmHg) central venous pressure (CVP, mmHg); left atrial pressure (LAP, mmHg); left ventricular enddiastolic pressure (LVEDP, mmHg)) and ECG monitoring blood samples were performed: 1) prior to operation (op); 2) prior to CPB; 3) 1 h CPB; 4) 5 min after CPB; 5) 1 h after CPB; 6) 6 h postoperative (postop); 7) 24 h postop; 8) 48 h postop; 9) 10 days postop. Also the left atrial diameter (LAD, mm) and the left ventricular enddiastolic diameter at Q (LVEDD, mm) pre- and postop were documented with m-mode echocardiography (Echo) and ejection fraction (EF, %) was calculated. The bypass operations were performed with intermittent aortic cross-clamping with open venae cavae (CVP: 0-5 mmHg) and moderate hypothermia. For the determination of ANP levels and TnT levels in arterial and venous blood, a double-antibody (AB) radioimmunoassay and an ELISA test were used. Concerning the patients with CAD there was a maximal increase of ANP from preoperative 90 +/- 10 (M +/- SEM) pg/ml (p < 0.05) up to intraoperative 380 +/- 38 pg/ml. Ten days postop, the ANP level was with 262 +/- 33 pg/ml still increased threefold in comparison to the preoperative level. TnT showed an increase from preoperative 0.02 +/- 0.01 ng/ml up to intraoperative 3.44 +/- 0.47 ng/ml. Ten days postop the TnT concentration was at the preoperative level with 0.13 +/- 0.11 ng/ml. Five minutes after bypass up to 48 h postop, ANP and TnT levels were correlated (p < 0.05, r = 3.4). There was an increase of the LAD from preoperative 42.2 +/- 1.1 mm up to 46.8 +/- 1.2 mm (p < 0.05) 10 days postop as determined by m-mode echo. LVEDD and EF changed from preoperative 51.1 +/- 0.9 mm and 73 +/- 2% to 54.5 +/- 1.2 mm and 65 +/- 4% 10 days postop. The significant increase of TnT (172-fold) indicates the cellular, myocardial injury, caused by the operation without signs in ECG recordings and no signs of congestive heart failure. The significantly increased ANP level up to the 10th day postop indicate sa very sensitive prolonged, postischemic dysfunction, which is not compensated 10 days postop.

On "Ischemic Preconditioning in Myocardial Revascularization with Intermittent Aortic Cross-Clamping"

On "Ischemic Preconditioning in Myocardial Revascularization with Intermittent Aortic Cross-Clamping"

Left ventricular diastolic function after coronary artery bypass grafting: A correlative study with three different myocardial protection techniques

Background: This study was designed to examine the effect of myocardial protection on diastolic function after cardiac operations. Methods: Subjects were patients with normal preoperative diastolic function who were scheduled for coronary artery bypass grafting. Group I received anterograde cardioplegia; group II received anterograde and retrograde cardioplegia; and group III was protected with ventricular fibrillation and intermittent aortic crossclamping. Operations were performed with mild hypothermia and ventricular venting through the left superior pulmonary vein in all cases. Left ventricular diastolic function was evaluated with pulsed-wave Doppler transesophageal echocardiography (samples at the mitral valve leaflet; four-chamber view) and left superior pulmonary vein flow velocity. The flow patterns were stored on videotape and sent to an independent investigator for analysis. Left ventricular ejection fraction was calculated with transesophageal echocardiography (short-axis view, two-dimensional and M-mode). Results: Left ventricular diastolic function, as measured by the ratio between the peak velocities during early filling and atrial contraction and by systolic diastolic superior pulmonary venous flow ratio, was significantly impaired in all three groups 5 minutes after discontinuation of cardiopulmonary bypass. At 1 hour after operation, these values had returned to control levels only in group III. There was an increased incidence of supraventricular arrhythmias in group III. There were no significant hemodynamic differences among the three groups. Conclusions: Left ventricular diastolic function was severely impaired after cardiopulmonary bypass. The degree of impairment depended on the myocardial protection used. The impairment in diastolic function was less when ventricular fibrillation and intermittent aortic crossclamping were used, and greater when anterograde and retrograde cardioplegia were used. (J Thorac Cardiovasc Surg 1997;114:254-60)

Intermittent aortic cross-clamping and cold crystalloid cardioplegia for low-risk coronary patients

Blood cardioplegic strategies have been shown to increase myocardial oxygen uptake, replenish depleted energy stores, and improve myocardial function and survival in the high-risk subset of patients. However, the superiority of these techniques over intermittent aortic cross-clamping and crystalloid cardioplegia in low-risk patients is still controversial. This study consisted of two parts. In the first part, we assessed the results of a recent cohort of 399 consecutive low-risk patients undergoing their first coronary artery bypass grafting between 1993 and 1995 using cold crystalloid cardioplegia (n = 128) and intermittent aortic cross-clamping (n = 271). In the second part of the study, 40 consecutive low-risk patients undergoing elective first time coronary artery bypass grafting were randomly divided into two equal groups. One group received cold crystalloid cardioplegia and the other group had myocardial management with intermittent aortic cross-clamping. The two groups were compared with respect to hemodynamic, biochemical and ultrastructural changes. The overall mortality rate, the perioperative myocardial in the need for intraaortic balloon pumps, and the need for inotropic agents were 0.25%, 1.5%, 1%, and 5.8%, respectively. No significant differences were observed between the groups with respect to these clinically defined end points. Both intermittent aortic cross-clamping and cold crystalloid cardioplegia techniques may be used safely in low-risk patients undergoing first-time coronary artery bypass grafting.

Myocardial protection for cardiac surgery.

The vast majority of cardiac surgical procedures are carried out using aortic cross-clamping and cardioplegie arrest [1]. Although alternate approaches such as operating on the normothermic empty beating heart, intermittent aortic cross-clamping or hypothermic ventricular fibrillation can be successfully utilized, the ability to carry out a meticulous and complete surgical procedure is generally best accomplished with the heart bloodless and still. Protective strategies in cardiac surgery are directed at both minimizing and reversing myocardial injury, which may occur not only secondary to ischemia induced with aortic cross-clamping, but also at the time of reperfusion. The ability to protect and resuscitate the heart from ischemic/reperfusion injury is of particular importance in patients with severe or complex disease, acute ischemia and/or compromised ventricular function.

Closure of muscular ventricular septal defects through a left ventriculotomy

To evaluate the results of closure of muscular ventricular septal defects through a left thoracotomy. Records of 23 children operated consecutively between 1972 and 1990 were studied. Age of patients was 2.8 +/- 3 years (2 months-10 years), weight 8.9 +/- 5.7 kg (2.6-22 kg). Ten patients (43%) had undergone one and 4 patients (17%) two previous cardiac operations. Late follow-up was obtained from direct examination of patients or from reports of their referring physicians. Bypass time was 89 +/- 28 min (66-167 min). The aorta was cross-clamped for 44 +/- 15 min (21-66 min). Until 1977 operations were performed with moderate hypothermia and intermittent aortic cross-clamping. After 1978 deep hypothermia (20-25 degrees C) and cold crystalloid cardioplegia was used. Ventricular septal defects not accessible from other approaches were closed through a small fish-mouth incision in the apex of the left ventricle. Patients' data were sampled and stored in a computerised database. Risk factors were evaluated by stepwise logistic regression. Four patients died in the hospital (17%); two died later. Two required reoperation for residual/recurrent defects. All patients, except two from abroad, were available for follow-up, which ranged from 36 months to 18 years (mean 11.3 years). All were in NYHA class I. Only two risk factors were identified: the number of ventricular septal defects (P < 0.05) and associated atrial septal defect (P < 0.02). Early echocardiographic evaluation showed good LV size and function in all except one patient, who had a perioperative septal infarction. Late echocardiography performed in six patients demonstrated normal LV shortening without evidence of regional wall abnormality. Left ventriculotomy is a useful approach for closure of low muscular ventricular septal defects in selected patients.

Intermittent warm aortic cross-clamping prevents cumulative ATP depletion, ventricular dysfunction and arrhythmias: Is it preconditioning?

Intermittent warm aortic cross-clamping prevents cumulative ATP depletion, ventricular dysfunction and arrhythmias: Is it preconditioning?

Intermittent aortic crossclamping prevents cumulative adenosine triphosphate depletion, ventricular fibrillation, and dysfunction (stunning): Is it preconditioning?

This study was designed to determine whether intermittent warm aortic crossclamping induces cumulative myocardial stunning or if the myocardium becomes preconditioned after the first episode of ischemia in canine models in vivo. The role of adenosine triphosphate catabolism and subsequent release of purines on reperfusion-mediated postischemic ventricular dysfunction and arrhythmias was assessed with the use of selective inhibitors of nucleoside transport, p-nitrobenzylthioinosine (NBMPR), and a specific adenosine deaminase inhibitor, erythro-9-[2-hydroxy-3-nonyl] adenine (EHNA). Thirty-two anesthetized dogs were instrumented to monitor left ventricular contractility, off bypass, by sonomicrometry. During cardiopulmonary bypass dogs were treated before ischemia with either saline solution (control group, n = 8) or EHNA (100 μmol/L) and NBMPR (25 μmol/L) (EHNA/NBMPR group, n = 8). Hearts were subjected to either 60 minutes of global ischemia and 120 minutes of reperfusion ( n = 16) or 6 episodes of 10 minutes of global ischemia and 10 minutes of reperfusion, followed by 60 minutes of reperfusion ( n = 16). Sixty minutes of sustained ischemia resulted in 80% loss of adenosine triphosphate and induced reperfusion-mediated ventricular fibrillation and severe left ventricular dysfunction in the control group. EHNA/NBMPR treatment augmented myocardial adenosine trapping during ischemia, attenuated ventricular fibrillation, and enhanced left ventricular functional recovery, despite similar depletion of adenosine triphosphate (80% loss). In the intermittent ischemia experiment, the first episode of 10 minutes of ischemia and reperfusion caused significant adenosine triphosphate depletion, ventricular fibrillation, and left ventricular stunning in both control and drug-treated groups. The prevalence of ventricular fibrillation was greater in the control group than in the drug-treated group after the first episode of ischemia ( p < 0.05). Adenosine was the major nucleoside accumulated in the myocardium at the end of 10 minutes of ischemia in the EHNA/NBMPR-treated group ( p < 0.05 versus control). Subsequent episodes of ischemia prevented ventricular fibrillation and did not cause cumulative left ventricular stunning in either group. Left ventricular function fully recovered in the EHNA/NBMPR-treated group after intermittent ischemia, but remained stunned in the control group. Unlike sustained ischemia, intermittent ischemia and reperfusion preserved myocardial adenosine triphosphate, limited purine release, and prevented ventricular fibrillation and cumulative stunning. These results suggest that intermittent ischemia and reperfusion augmented the endogenous protective mechanism or mechanisms of "preconditioning." Nucleoside trapping improved functional recovery after sustained or repetitive ischemia. It is concluded that adenosine triphosphate preservation or blockade of nucleoside transport may play an important role in the activation of endogenous myocardial protective mechanisms that "precondition" against subsequent ischemic stress. (J T HORAC C ARDIOVASC S URG 1995;110:328-39)

The effects of cardiopulmonary bypass on systemic and coronary levels of von Willebrand factor.

Von Willebrand factor antigen (vWF Ag) is a marker of endothelial injury which has been shown to rise during surgical procedures, including cardiopulmonary bypass (CPB). The aim of this study was to determine whether intermittent aortic cross-clamping during CPB causes the release of vWF Ag from the coronary vascular bed, which would suggest coronary vascular endothelial cell perturbation. Fifteen consecutive patients undergoing CPB with aortic cross-clamping during coronary artery bypass surgery and/or valve replacement by the same surgeon were studied. Paired venous and coronary sinus samples were taken pre- and post-thoracotomy, prior to cross-clamping on CPB, and 1, 5 and 10 minutes after release of the aortic cross-clamp. Plasma vWF Ag (IU/ml) was measured by ELISA. Venous vWF Ag measured prior to skin incision was 0.75 +/- 0.11 IU/ml (mean +/- SEM) and fell to 0.53 +/- 0.07 IU/ml after institution of CPB but prior to aortic cross-clamping (P < 0.01 vs pre-incision sample). Coronary sinus vWF Ag measured prior to aortic cross-clamping was 0.54 +/- 0.06 IU/ml (P = NS vs paired venous sample). At 1, 5 and 10 min after release of the aortic cross-clamp there was a progressive rise in vWF Ag in both venous and coronary sinus samples (1 min: 0.67 +/- 0.05 IU/ml vs 0.75 +/- 0.10 IU/ml, 5 min: 0.73 +/- 0.07 IU/ml vs 0.76 +/- 0.09 IU/ml, 10 min: 0.74 +/- 0.08 IU/ml vs 0.79 +/- 0.09 IU/ml; P = NS venous vs coronary sinus, respectively). Levels of vWF Ag were highest immediately prior to the termination of CPB (venous: 0.95 +/- 0.12 IU/ml; coronary sinus: 0.91 +/- 0.14 IU/ml). We conclude that cardiac surgery using CPB with aortic cross-clamping is associated with a progressive rise in coronary sinus and venous levels of vWF Ag.(ABSTRACT TRUNCATED AT 250 WORDS)

Coronary artery bypass surgery: current practice in the United Kingdom.

To assess current clinical practice in coronary artery bypass surgery and compare it with a previous survey conducted five years ago. United Kingdom. Postal questionnaires were sent in March 1993 to 120 consultant cardiac surgeons currently performing coronary artery bypass surgery. 104 (87%) were returned by May 1993. The 104 surgeons who returned the questionnaire performed an estimated total of 25,234 coronary artery bypass operations in 1992 with an average case load per surgeon similar to that in 1987 (243 v 214, NS). The internal mammary artery was regarded as the conduit of choice by 101 surgeons (97%) and was used in 93% of bypass grafts to the left anterior descending coronary artery compared with 73% in 1987 (p < 0.001) but only in 7% of grafts to the circumflex and right coronary systems. There was also a significant increase in the number of surgeons using both internal mammary arteries (88% v 59%, p < 0.01) but only a small increase in those using the internal mammary artery as a sequential graft (55% v 44%, NS). The age of the patient remains one of the main contraindications to the use of the internal mammary artery (40%), together with insufficient mammary flow (42%), endarterectomy (22%), and unstable angina (17%). The right gastroepiploic and inferior epigastric arteries were used only occasionally (3%) when the internal mammary artery or the saphenous vein were not available. Most surgeons (96%) still advocate the use of aspirin to enhance graft patency, with 87% of surgeons continuing treatment indefinitely, compared with 50% in the previous survey (p < 0.001). As for methods of myocardial protection, 72% of surgeons used cardioplegic arrest whereas 28% preferred intermittent aortic cross clamping and fibrillation. It is the consensus among British cardiac surgeons that the internal mammary artery is the graft conduit of choice. Its use has been significantly extended over the past five years (1987 to 1992) suggesting a quick response to advancing scientific knowledge. The use of alternative arterial conduits is still limited, perhaps as a reflection of the relative lack of information on their long-term performance. The recently advocated technique of retrograde cardioplegia and continuous warm cardioplegia is not yet popular.

Preconditioning the human heart during aorto-coronary bypass surgery

Ischaemic preconditioning, with brief periods of ischaemia separated by reperfusion, increases myocardial resistance to infarction. In addition, preconditioning leads to preservation of myocardial adenosine triphosphate (ATP) during ischaemia. We propose that ischaemic preconditioning may share fundamental similarities with intermittent aortic cross-clamping utilised during aorto-coronary bypass surgery. The aim of this study was to test the hypothesis that controlled aortic cross-clamping is a form of preconditioning using conservation of ATP as the end point. Patients randomised to the preconditioned group (preconditioned, n = 10 patients), received a preconditioning stimulus of two 3-min periods of cross-clamping separated by 2 min of reperfusion prior to an ischaemic insult of 10 min ischaemia and ventricular fibrillation. In the control group (control, n = 10 patients) hearts received 10 min cross-clamping with fibrillation without prior preconditioning. Myocardial ATP, creatine phosphate (CP), and lactate were determined from biopsy specimens taken at the onset of cardiopulmonary bypass (A), at the end of preconditioning (B), and at the end of 10 min of ischaemic insult (C). expressed as mean +/- SE (mumol/g dry weight). Preconditioning resulted in a significant depletion of the myocardial ATP content (preconditioned, B: 11.7 +/- 0.9 vs A: 19.8 +/- 1.4; P < 0.01). Furthermore 10 min of ischaemia resulted in a significant depletion of ATP in the control patients (control, C: 7.2 +/- 0.3 vs B: 19.5 +/- 1.2; P < 0.005).(ABSTRACT TRUNCATED AT 250 WORDS)

Blood cardioplegia with warm reperfusion versus intermittent aortic crossclamping in myocardial revascularization: Randomized controlled trial

To compare the efficiency of two methods of myocardial protection--blood cardioplegia and warm reperfusion with aspartate-glutamate enrichment of the solution versus intermittent aortic crossclamping--we randomized 60 patients for coronary artery bypass grafting. Hemodynamic parameters and hospital mortality were the end points. Pathologic antecedents and preoperative clinical conditions were similar in both group I (blood cardioplegia, 30 patients) and group II (aortic crossclamping, 30 patients). An average of 2.9 grafts per patient were performed in group I and 3.1 in group II. Duration of extracorporeal circulation was 100 +/- 28 minutes in group I and 85 +/- 23 minutes in group II (p < 0.05). The total time of aortic crossclamping was 62.8 +/- 24.5 minutes in group I and 44.3 +/- 14.9 minutes in group II (p < 0.05). There were comparable increases in cardiac index in group I and group II from the preoperative period to the first postoperative day, but none of these changes reached statistical significance. There were two deaths, one in the cardioplegia group (3.3%) and another in the intermittent aortic crossclamping group (3.3%). In conclusion, in myocardial revascularization, intermittent aortic crossclamping and blood cardioplegia with warm reperfusion enriched with aspartate-glutamate solution are methods of similar efficiency.

Atrial fibrillation after coronary artery bypass grafting: a comparison of cardioplegia versus intermittent aortic cross-clamping

Supraventricular tachyarrhythmias following coronary artery bypass grafting are a common cause of postoperative morbidity, with a reported incidence of 10-40%. Two techniques of myocardial protection were assessed to determine their influence on the occurrence of postoperative supraventricular tachyarrhythmias. Group I (n = 82) received cold potassium cardioplegia combined with topical hypothermia and systemic cooling to 28 degrees C. Group II (n = 88) were protected by intermittent aortic cross-clamping with a systemic temperature of 32 degrees C. The overall incidence of atrial fibrillation/flutter was 22.3%. No significant difference was detected in the incidence of clinically important atrial fibrillation/flutter between the two groups [21/82 (25.6%) in group I versus 17/88 (19.3%) in group II, P > 0.25]. There was a positive association with age: in patients over 60 years the incidence of arrhythmias (31.8%) was significantly greater than in those less than 60 years (12.9%), P < 0.01. Sex, cardiopulmonary bypass times, aortic cross-clamp times, number of coronary grafts, end-operative creatine kinase myocardial band isoenzyme, right coronary endarterectomy and perioperative myocardial infarction had no association with the occurrence of postoperative atrial tachyarrhythmias.