Intermittent Antegrade Warm Blood Cardioplegia Research Articles

The effect of cold crystalloid versus warm blood cardioplegia on the myocardium during coronary artery bypass grafting

Background: The optimal cardioplegic solution is still debated. The objective of this study was to compare the effect of cold crystalloid versus warm blood cardioplegia on the myocardial injury during coronary artery bypass grafting.
 Methods: The study included 34 consecutive patients who underwent elective primary on-pump isolated coronary artery bypass grafting from 2016 to 2019. We randomly assigned the patients into two groups. Group (ICCC) (n= 17) received intermittent antegrade cold crystalloid cardioplegia and Group (IWBC) (n= 17) received intermittent antegrade warm blood cardioplegia.
 Results: There was no difference in the preoperative and operative variables between groups. The time taken by the heart to regain normal sinus rhythm was significantly longer in the cold crystalloid group (7.06 ± 1.8 vs. 2.17 ± 0.8 minutes, p<0.001) with a higher rate of reperfusion ventricular arrhythmia (35% versus 6%; p=0.03) compared to the warm blood cardioplegia group. Both coronary sinus acid production and lactate level were significantly higher in the warm blood group than in the cold crystalloid group (p< 0.001 and 0.043, respectively). The ischemic ECG changes and the severity of new segmental wall motion abnormalities were non-significantly different between both groups (p= 0.68 and 0.67, respectively). Postoperative CK-MB and cTnI levels in all-time points were not significantly different between groups (p= 0.46 and 0.37, respectively). ICU (2.29 ± 0.77 vs. 2.41 ± 0.87 days, p= 0.68) and hospital stay (9.28 ± 0.76 vs. 9.42 ± 0.88 days, p= 0.62) were non-significantly different between both groups.
 Conclusion: Intermittent antegrade cold crystalloid cardioplegia was associated with attenuated myocardial metabolism. However, it was associated with a longer time to regain normal sinus rhythm and more reperfusion ventricular arrhythmias. We did not find differences in the clinical and echocardiographic outcomes and cardiac enzymes between cold crystalloid and warm blood cardioplegia.

Warm blood cardioplegia versus cold crystalloid cardioplegia for coronary artery bypass grafting (CABG) in patients with low ejection fraction

BackgroundPatients with reduced ejection fraction (EF) undergoing CABG are more likely to develop postoperative morbidity and mortality. It is controversial about which cardioplegia solution, temperature, and method of administration ensure optimal cardiac muscle preservation during CABG surgery.Aim of the studyThe aim of the study was to compare intermittent antegrade warm blood cardioplegia with cold crystalloid cardioplegia during CABG in patients with low EF (30–40%).MethodsPatients (n = 100) undergoing elective isolated on-pump CABG were prospectively randomized into group I (n = 50) which received antegrade cold crystalloid cardioplegia and group II (n = 50) which received antegrade warm blood cardioplegia. Blood samples were collected immediately and 12 and 24 h postoperatively. CK-MB and cardiac troponin I were measured and compared between the two groups. Other indicators such as use of inotropic support and use of intra-aortic balloon counter pulsation (IABC) were also documented.ResultsPreoperative demographic and clinical variables were matched in both groups. However, postoperative CK-MB and troponin I were higher in group I compared to group II. There was less need for inotropic support and IABC with better postoperative course in group II than in group I.ConclusionThere was a significant reduction in the release of cardiac enzymes and less need for inotropic support with better postoperative outcome in patients who received antegrade warm blood cardioplegia versus cold crystalloid cardioplegia.

Intermittent Antegrade Warm Blood Cardioplegia: What Is Next?

The introduction of warm heart surgery was a radical change in the concept of myocardial protection. In 1992, we applied a protocol for intermittent antegrade warm blood cardioplegia (CPL), which acquired some popularity for its simplicity and effectiveness. The possibility to deliver the warm blood CPL intermittently using the antegrade route attracted the attention of the scientific world, as the surgical procedure was less complicated. In this report, our aim is to focus on the changes that the protocol underwent over time and the reasons why these changes were made.

MYOCARDIAL DAMAGEq

Background: Intermittent antegrade warm blood cardioplegia is routinely usedas a mean of myocardial protection since its introduction. There is a considerable debate onthe longest time off cardioplegia interval during aortic cross clamping. Objective: To see thefrequency and extent of myocardial damage in patients undergoing CABG receiving intermittentantegrade warm blood Cardioplegia at LTOC (longest time off cardioplegia) 11-15 minutes(Group I) and 16-20 minutes (Group II). Patients and Methods: A randomized prospectivestudy involving 94 patients was arranged to see the safe periods of intermittency. There weretwo groups of patients having LTOC of 11-15 minutes (Group I) and 16-20 minutes (GroupII). 20 minutes was the upper limit. The duration of study was from 1-09-2013 to 10-02-2014.Data was analyzed using SPSS Version 16. Independent sample t-test and chi-square wereapplied to see the significance. Results: Mean age was 54.1±9.36 years. There were moremales as compared to females. More than 50% of the patients had Hypertension and Diabetes.There was no urgent surgery. Triple vessel disease (TVD) was present in 48.9% patients and40.4% had Double vessel disease (DVD). Average blood flow during CPB was 2.4±0.14 (L/min.m-2). Average body temperatures were 31.7±2.30C. Cardioplegia temperature was 36-370C.According to Left Ventricular Function Classification, 43.6% of the patients were of LV grade IIand 10.6% of LV grade III. There was no significant increase in the levels of CK-MB in two groups.77.8% patient in Group I and 66.7% in Group II gained spontaneous rhythm (p-value 0.16). IABPwas inserted in 5.4% patients in group I and 5.6% in group II (p-value 0.97). There was no failureto wean off from bypass and no peri-operative mortality. The levels of inotropes viz dopamineand epinephrine on weaning were also almost the same. Perioperative MI occurred only in 7patients (ruled out by biochemical evidence). Conclusions: A reasonable margin of safetyexists with intermittent antegrade warm blood cardioplegia in these two groups. So the LTOC(longest time off cardioplegia) up to 20 minutes is unlikely to lead to adverse clinical outcomesand is clinically acceptable.

Warm-blood cardioplegia with low or high magnesium for coronary bypass surgery: a randomised controlled trial

Objective: Magnesium (Mg2+) is cardioprotective and has been routinely used to supplement cardioplegic solutions during coronary artery bypass graft (CABG) surgery. However, there is no consensus about the Mg2+ concentration that should be used. The aim of this study was to compare the effects of intermittent antegrade warm-blood cardioplegia supplemented with either low- or high-concentration Mg2+. Methods: This study was a randomised controlled trial carried out in two cardiac surgery centres, Bristol, UK and Cuneo, Italy. Patients undergoing isolated CABG with cardiopulmonary bypass were eligible. Patients were randomised to receive warm-blood cardioplegia supplemented with 5 or 16 mmol l−1 Mg2+. The primary outcome was postoperative atrial fibrillation. Secondary outcomes were serum biochemical markers (troponin I, Mg2+, potassium, lactate and creatinine) and time-to-plegia arrest. Intra-operative and postoperative clinical outcomes were also recorded. Results: Data from two centres for 691 patients (342 low and 349 high Mg2+) were analysed. Baseline characteristics were similar for both groups. There was no significant difference in the frequency of postoperative atrial fibrillation in the high (32.8%) and low (32.0%) groups (risk ratio 1.03, 95% confidence interval, CI, 0.82–1.28). However, compared with the low group, troponin I release was 28% less (95% CI 55–94%, p = 0.02) in the high-Mg2+ group. The 30-day mortality was 0.72% (n = 5); all deaths occurred in the high-Mg2+ group but there was no significant difference between the groups (p = 0.06). Frequencies of other major complications were similar in the two groups. Conclusions: Warm-blood cardioplegia supplemented with 16 mmol l−1 Mg2+, compared with 5 mmol l−1 Mg2+, does not reduce the frequency of postoperative atrial fibrillation in patients undergoing CABG but may reduce cardiac injury. (This trial was registered as ISRCTN95530505.)

The Efficacy and Safety of Extending the Ischemic Time with a Modified Cardioplegic Technique for Coronary Artery Surgery

The need to intermittently discontinue the administration of cardioplegia in order to complete the surgical procedure is a major drawback of antegrade warm blood cardioplegia. An ischemic time of 15 minutes is generally considered safe based on empirical observation. The aim of this study was the evaluation of the efficacy and safety of an intermittent warm blood cardioplegia with intervals between administrations prolonged to 25 minutes. Ninety-seven patients undergoing primary elective coronary artery revascularization were prospectively randomized into two groups. The first, Intermittent Antegrade Warm Blood Cardioplegia (IAWBC) group, comprising 49 patients, received standard intermittent antegrade warm blood cardioplegia repeated every 15 minutes. The second, Modified Intermittent Antegrade Warm Blood Cardioplegia (M-IAWBC) group, comprising 48 patients, received intermittent antegrade warm blood cardioplegia supplemented with magnesium sulfate (MgSO(4)), delivered in volumes proportional to the ventricular mass and repeated every 25 minutes. The clinical outcomes were evaluated. The levels of creatine kinase-MB (CK-MB) isoenzyme, in addition to the echocardiographic assessment of septal dyskinesia and tricuspid annulus plane systolic excursion (TAPSE), have been used as markers of myocardial damage. There were no statistically significant differences in clinical outcomes, need for inotropes and vasodilators, length of stay in the intensive care unit, and postoperative levels of CK-MB between the two groups. Likewise, postoperative echocardiographic assessment showed no relevant differences. Administration of warm antegrade cardioplegic solution supplemented with MgSO(4), delivered in volumes proportional to ventricular mass every 25 minutes, provides adequate myocardial protection for coronary artery surgery.

Evaluation of myocardial metabolism with microdialysis during bypass surgery with cold blood- or Calafiore cardioplegia

For the first time, microdialysis was used to investigate in vivo and online the myocardial metabolism during and after cardiac surgery in patients treated with two different methods of myocardial protection. Thirty patients underwent standard CABG with one of two different methods of myocardial protection. The patients were randomised to receive either cold blood (COLD group) or warm modified Calafiore cardioplegia (WARM group). Microdialysis probes were implanted into the myocardium of left ventricular apical region of the heart. Cardioplegia was given antegrade only. Microdialysis measurements were performed at time intervals before, during and 24 h after cardiopulmonary bypass and analysed for glucose, lactate, pyruvate and glycerol. Myocardial lactate concentrations were significantly higher in the WARM group compared with that of the COLD group, while serum lactate was comparable. Glycerol was significantly higher at the end of the clamping time in the WARM group. At the same time the glucose-lactate ratio as a marker of nutritional disorder had significantly lower levels in the WARM group. The cumulative CK-MB release over 24 h was significantly higher in those hearts protected with warm blood. The oxidative stress measured was significantly higher in patients undergoing CABG using modified Calafiore cardioplegia, whereas the cold cardioplegia minimised the effects of aortic clamping. The results indicate that cold cardioplegia offers superior protection of the heart, in terms of more rapid normalisation of myocardial metabolism. In elective myocardial revascularisation, intermittent antegrade warm blood cardioplegia is a comparable safe method of myocardial protection. However, in patients referring to a long clamping time, advantages of cold cardioplegia for myocardial revascularisation may be magnified.

Left ventricular function and chronotropic responses after normothermic cardiopulmonary bypass with intermittent antegrade warm blood cardioplegia in patients undergoing coronary artery bypass grafting

Recent studies indicate that normothermic cardiopulmonary bypass (CPB) with intermittent antegrade warm blood cardioplegia (IAWBC) may have metabolic and clinical advantages, but limited data exist on its effects on myocardial function. Therefore, we investigated the acute effects of this approach on systolic and diastolic left ventricular function and on chronotropic responses. In 10 patients undergoing isolated CABG we obtained on-line left ventricular pressure-volume loops using the conductance catheter before and after normothermic CPB with IAWBC. Steady state and load-independent indices of left ventricular function derived from pressure-volume relations were obtained during right atrial pacing (80-100-120 beats/min) to determine baseline systolic and diastolic function and chronotropic responses. The mean time of CPB was 105+/-36 min (median 103, range 60-167 min) with a mean aortic cross-clamp time of 75+/-27 min (median 69, range 43-129 min). Baseline (80 beats/min) end-systolic elastance (E(ES)) did not change after CPB (1.22+/-0.53 to 1.12+/-0.28 mm Hg/ml, P>0.2), while the diastolic chamber stiffness constant (k(ED)) significantly increased (0.014+/-0.005 to 0.040+/-0.007 ml-1, P=0.018) and relaxation time constant (tau) significantly decreased (61+/-3 to 49+/-2 ms, P=0.004). Before CPB, incremental atrial pacing had no significant effects on E(ES) and tau but significant negative effects on kED (0.014+/-0.005 to 0.045+/-0.012 ml-1, P=0.013). After CPB, atrial pacing had significant positive effects on E(ES), tau and kED (E(ES): 1.12+/-0.28 to 2.60+/-1.54 mm Hg/ml, P=0.021; tau: 49+/-2 to 45+/-2 ms, P=0.009; kED: 0.040+/-0.007 to 0.026+/-0.005 mm Hg, P=0.010), indicating improved systolic and diastolic chronotropic responses. On-pump normothermic CABG with IAWBC preserved systolic function, increased diastolic stiffness, and improved systolic and diastolic chronotropic responses. Normalization of the chronotropic responses post-CPB is likely due to effects of successful revascularization and subsequent relief of ischemia.

Four Years’ Experience With a Miniaturized Extracorporeal Circulation System and Its Influence on Clinical Outcome

It has been suggested that the morbidity associated with cardiopulmonary bypass can be attributed in part to the blood-material and blood-air interactions in the extracorporeal circulation (ECC). A recently introduced minimized ECC-system (MECC System) should be able to reduce these negative effects associated with ECC. A retrospective analysis was performed comprising 485 patients who were operated on for elective coronary artery bypass grafting (CABG) using the MECC System with intermittent antegrade warm blood cardioplegia (group 1) from January 2000 to February 2004. A control group consisted of 485 patients (group 2) undergoing elective CABG in the same period using a conventional ECC and cold crystalloid cardioplegia. There were no significant differences between the two groups in terms of the duration of intubation following surgery, the length of intensive care unit-stay and the total hospital stay. Although the 30-day mortality was similar between the two groups, the incidence of postoperative complications and the perioperative use of blood products were significantly higher in the control group compared to the MECC group. The MECC System may serve as an alternative and less invasive approach to conventional ECC.

812 Systolic and diastolic ventricular performance after normothermic CPB with intermittent antegrade warm blood cardioplegia

812 Systolic and diastolic ventricular performance after normothermic CPB with intermittent antegrade warm blood cardioplegia

Cardiac function after intermittent antegrade warm blood cardioplegia: contribution of the double-indicator dilution technique

To evaluate cardiac performance following coronary artery surgery using two different techniques of cardioplegia. Randomized prospective study. Adult cardiothoracic intensive care unit in a university hospital. Thirty patients undergoing isolated coronary surgery. Patients were randomized to receive either intermittent antegrade warm blood cardioplegia with normothermic bypass (group 1) or combined antegrade and retrograde cold crystalloid cardioplegia with hypothermic bypass (group 2). Hemodynamic evaluation included conventional measurements from a pulmonary artery catheter and data obtained by thermal dye dilution utilizing an arterial thermistor-tipped fiberoptic catheter. The only major difference between groups was a significantly higher right atrial pressure in group 2, from 4 h to 24 h after surgery (8.8 +/- 2.6 vs. 11.8 +/- 3.2 mmHg at 4 h and 11 +/- 3.1 vs. 8.5 +/- 1.8 mmHg at 24 h, P = 0.04). After cold cardioplegia a significant increase in right atrial pressure was observed (7.5 +/- 3.1 before surgery vs. 11.4 +/- 3 mmHg at 8 h, P = 0.003) whereas right ventricular end diastolic volume index did not increase significantly, suggesting impaired right ventricular diastolic compliance in this group. Until 24 h after surgery cold cardioplegia is associated with impaired right ventricular filling, which seems better preserved by intermittent antegrade warm blood cardioplegia. End-diastolic volume measurement with the double-indicator technique allows differentiation between systolic and diastolic dysfunction.

Intermittent antegrade warm blood cardioplegia for CABG: extended interval of cardioplegia

Background. Intermittent delivery of warm cardioplegia provides a bloodless surgical field, but it is clinically important to evaluate the periods of normothermic ischemia. The aims of this study are to compare intermittent antegrade warm blood cardioplegia (IAWBC) with intermittent antegrade cold blood cardioplegia (IACBC) groups in terms of myocardial protection, and also to evaluate whether the length of ischemic time in the IAWBC group has an effect on myocardial dysfunction.Methods. This study is based on a retrospective review of patients who underwent elective coronary artery bypass surgery: 162 consecutive patients with IAWBC and 107 consecutive patients with IACBC.Results. The creatinine kinase peak was smaller in the IAWBC group compared with the IACBC group (p < 0.0001). The cardiac index after cardiopulmonary bypass was higher in the IAWBC group (p < 0.02), and the amount of inotropic support required to wean from cardiopulmonary bypass was less in the IAWBC group compared with the IACBC group (p < 0.0001).Conclusions. IAWBC with 30 minutes of ischemia provides to be clinically acceptable myocardial protection for coronary bypass surgery.

Serum S-100 protein release and neuropsychologic outcome during coronary revascularization on the beating heart: A prospective randomized study

Objectives: Our purpose was to establish whether coronary revascularization on the beating heart without cardiopulmonary bypass is less harmful to the brain than conventional surgery with cardiopulmonary bypass as indicated by measures of cognitive function or by changes in serum concentrations of S-100 protein, a recognized biochemical marker of cerebral injury. Methods: We conducted a prospective randomized trial in which the assessors of the outcome measures were blind to the treatment received. Sixty patients without known neurologic abnormality, undergoing coronary revascularization, were prospectively randomized to 1 of 2 groups: (1) cardiopulmonary bypass (32°C-34°C) and cardioplegic arrest (on pump) with intermittent antegrade warm blood cardioplegia or (2) surgery on the beating heart (off pump). Neuropsychologic performance was assessed before and 12 weeks after the operation. Serum S-100 protein concentration was measured at intervals up to 24 hours after the operation. Results: The groups had similar preoperative characteristics. There were no deaths or major neurologic complications in either group, nor was there any difference between groups in the chosen index of neurologic deterioration. Serum S-100 protein concentrations were higher in the on-pump group at 30 minutes, but any such difference between groups had disappeared 4 hours later. The extent of the changes in S-100 protein was unrelated to the index of neuropsychologic deterioration. Conclusions: The changes in S-100 protein concentration suggest that the brain and/or blood-brain barrier may be more adversely affected during coronary artery surgery with cardiopulmonary bypass than during surgery on the beating heart, but that this may not be reflected in detectable neuropsychologic deterioration at 12 weeks. (J Thorac Cardiovasc Surg 2000;119:148-54)

Assessment of the myocardial protective effect of antegrade warm blood cardioplegia by measuring the release of biochemical markers.

Intermittent warm blood cardioplegia has been reported as a valuable alternative for myocardial protection in cardiac surgery; however, conflicting experimental data have been published. To assess the clinical effectiveness of intermittent warm cardioplegia, we measured the release of troponin-T (Tn-T), a highly sensitive and specific marker of myocardial damage, and creatine kinase MB isoenzyme (CK-MB), in 12 patients who underwent elective coronary artery bypass grafting (CABG) with antegrade intermittent warm blood cardioplegia (37 degrees C) being the warm group, in comparison with 16 patients who underwent CABG with antegrade intermittent cold blood cardioplegia (4 degrees C) being the cold group. Blood samples were taken to determine the serum concentrations of CK-MB and Tn-T, at the induction of anesthesia, then 3, 6, 12, and 24h after the termination of cardiopulmonary bypass (CPB). The peak increase in serum CK-MB levels, 3h after CPB, was significantly lower in the warm group than in the cold group, at 27.8+/-7.8 IU/l vs. 40.8+/-12.6 IU/l, respectively (P = 0.0042). The serum Tn-T 12 h after CPB was significantly lower in the warm group than in the cold group, at 1.40+/-0.71 ng/ml vs. 2.06+/-0.95 ng/ml, respectively (P = 0.049). In conclusion, intermittent antegrade warm blood cardioplegia showed effective myocardial protection in elective CABG.

Randomized trial of intermittent antegrade warm blood versus cold crystalloid cardioplegia

Background. We performed a prospective randomized trial to compare intermittent antegrade warm blood cardioplegia with intermittent antegrade and retrograde cold crystalloid cardioplegia. Methods. Two hundred consecutive patients scheduled for isolated coronary bypass surgical procedures were randomized into two groups: Group 1 (n = 92) received cold crystalloid cardioplegia with moderate systemic hypothermia, group 2 (n = 108) received intermittent antegrade warm blood cardioplegia with systemic normothermia. Preoperative, intraoperative, and postoperative data were prospectively collected. Results. For the same median number of distal anastomoses, cardiopulmonary bypass duration and total ischemic arrest duration (57.3 ± 20.5 versus 75 ± 22.1 minutes, p < 0.001) were shorter in group 2 than in group 1. Apart from a higher right atrial pressure in the cold cardioplegia group, no hemodynamic difference was observed. Aspartate aminotransferase, creatine kinase-MB fraction, and cardiac troponin I levels were significantly lower in group 2 than in group 1. Outcome variables were not significantly different. Conclusions. Intermittent antegrade warm blood cardioplegia results in less myocardial cell damage than cold crystalloid cardioplegia, as assessed by the release of cardiac-specific markers. This beneficial effect has only marginal clinical consequences. Normothermic bypass has no deleterious effect on end-organ function.

Ultrastructural assessment of the myocardium receiving intermittent antegrade warm blood cardioplegia

Ultrastructural changes in the myocardium during intermittent warm blood cardioplegia were studied in 12 dogs. During cardiopulmonary bypass, dogs received three 5-minute periods of warm blood cardioplegia, interrupted by three 10-minute episodes of ischemia in group A or three 20-minute episodes of ischemia in group B. Biopsy specimens were taken from the right ventricle before each cardioplegic infusion and at the end of the aortic cross-clamp period to analyze ultrastructural changes. Functional recovery was measured after cardiopulmonary bypass. Mild and principally reversible ultrastructural changes were observed in group A. In group B, moderate ultrastructural changes were observed, and these changes suggested cumulative ischemic injury. Functional recovery was good in group A, but significantly deteriorated in group B. We concluded that three 10-minute interruptions of warm blood cardioplegia cause mild ultrastructural changes and seem to be safe, but three 20-minute interruptions cause cumulative ischemic injury in normal dog hearts.

Time Dependence of Endothelium-Mediated Vasodilation by Intermittent Antegrade Warm Blood Cardioplegia

The technique of intermittent antegrade warm blood cardioplegia (IAWBC) exposes the heart to brief periods of normothermic ischemia. This may impair endothelial function in coronary arteries. Three cardioplegic technique were tested in porcine hearts arrested for 32 to 36 minutes and reperfused for 30 minutes: IAWBC, antegrade cold blood cardioplegia (ACBC), and antegrade cold crystalloid cardioplegia (ACCC). In the hearts arrested with IAWBC, three different intervals of ischemia were used: three 10-minute intervals (IAWBC1), two 15-minute intervals (IAWBC2), and one 30-minute interval (IAWBC3). Rings from the coronary arteries were used to evaluate in vitro the contractile responses to U46619 and the relaxant responses to bradykinin, A23187, and sodium nitroprusside. All six groups (treatment groups and control group) displayed similar responses to U46619 (30 nmol/L) and nitroprusside. In the IAWBC1, IAWBC2, AND ACBC groups, endothelium-dependent relaxations to bradykinin and A23187 were preserved compared with controls, whereas those of the ACCC and IAWBC3 groups were significantly impaired (bradykinin: control, 8.72 +/- 0.07; IAWBC1, 8.73 +/- 0.03; IAWBC2, 8.65 +/- 0.05; IAWBC3, 8.30 +/- 0.07 [p < 0.05]; ACBC, 8.50 +/- 0.03; ACCC, 8.25 +/- 0.09 [p < 0.05]; A23187: control, 7.07 +/- 0.08; IAWBC1, 7.07 +/- 0.06; IAWBC2, 7.04 +/- 0.03; IAWBC3, 6.64 +/- 0.01 [p < 0.05]; ACBC, 6.80 +/- 0.05; ACCC, 6.60 +/- 0.08 [p < 0.05]; nitroprusside: control, 6.19 +/- 0.1; IAWBC1, 6.19 +/- 0.07; IAWBC2, 6.03 +/- 0.03; IAWBC3, 6.08 +/- 0.05; ACBC, 6.04 +/- 0.2; ACCC, 6.05 +/- 0.03; all values are expressed as the negative logarithm of the concentration producing 50% of the maximal response). Myocardial preservation with IAWBC with ischemic intervals of 15 minutes or shorter does not alter the endothelium-dependent relaxation to bradykinin or A23187 in porcine coronary arteries, but these responses are significantly impaired by ACCC and IAWBC with an ischemic interval of 30 minutes.

Case 5—1996 thrombosis after the use of a heparin-coated cardiopulmonary bypass circuit in a patient with heparin-induced thrombocytopenia

A 64-year-old, 165-cm, 58-kg woman was admitted to the hospital with an inferior myocardial infarction. She underwent an emergent percutaneous transluminal coronary angioplasty (PTCA) complicated by an early reocclusion necessitating a second PTCA. The second PTCA complicated itself by the dissection of the right coronary artery (RCA), necessitating the placement of four stents in the RCA. The patient was then treated with porcine heparin (H) for 7 days. Warfarin was progressively titrated to a prothrombin time of 23% (international normalized ratio = 3.8), and heparin was then stopped. After 3 days of effectwe warfarin treatment, she suddenly developed cardiogenic shock with third-degree atrioventricular block, necessitating resuscitation maneuvers, intubation, placement of an intra-aortic balloon pump, and a pacemaker. After this resuscitation, she recovered well except for a right hemiparesis that was attributed to a prolonged hypotensive state. Coronary angiography disclosed a reocclusion of the RCA. Fibrinolytic therapy was then administered, and a continuous infusion of heparin was reintroduced. Forty-eight hours after her ischemic event, a cerebral computed tomography (CT) scan was normal, and she had no neurologic sequelae. Nine days later, despite receiving a continuous infusion of heparin, she became ischemic in the right coronary artery territory, and an emergent coronary revascularization was planned. While evaluating the patient's files, the attending anesthesiologist found that the platelet level was below 35,000/mm 3 from the beginning of the second heparin administration 10 days earlier (Fig 1), and he suspected a syndrome of heparin-induced thrombocytopenia (HIT). Because of the presence of four stents in the patient's RCA and owing to her history of the repetitive coronary occlusions, the cardiologists refused to stop the heparin infusion. This infusion was therefore stopped in the operating room. A central venous catheter was already in place, a radial arterial catheter was then placed under local anesthesia, and both were flushed with 0.9% saline without heparin. Anesthesia was induced with etomidate and sufentanil, and muscle paralysis achieved with pancuronium. Anesthesia was maintained with midazolam, and a continuous infusion of sufentanil, 2 Ixg/kg/hr. Iloprost is not available in Belgium; neither are the heparin substitutes proposed in the literature. The anesthesiologist had no experience with the use of low-molecularweight heparin (LMWH) during bypass. Therefore, he elected to use a heparin-coated cardiopulmonary bypass (CPB) circuit (HC-CPB) (Durafio II; Bentley [Englewood, CO], because of its theoretical advantages of biocompatibility and protection of platelets against activation caused by contact with the artificial surfaces. Only 50 IU/kg of porcine heparin were administered in place of the usual 300 IU/kg. Two saphenous grafts were sutured on the RCA. The procedure was performed under normothermia and intermittent antegrade warm blood cardioplegia. Aortic crossclamp time was 34 minutes, and CPB lasted 55 minutes. No pharmacologic support was needed to come off bypass. The platelet level was 34,000/mm 3 before surgery and 39,000/mm 3 after 50 IU/kg of H. It decreased to 22,000/ mm 3 after 7 minutes of CPB, possibly because of hemodilution, and returned to 39,000/mm 3 after discontinuation of CPB. Activated coagulation times with kaolin (ACT) (Hemotec; Medtronic [Uden, The Netherlands]) were 151 seconds before heparin administration, 231 seconds after 50 IU/kg of H, 445 and 443 seconds during CPB, and 295 seconds after CPB. Only 10 mg (2,000 IU) of protamine were then administered, and ACT returned to 148 seconds (Fig 2). After administration of another 1,000 IU of protamine, the ACT was 82 seconds. Despite this, the patient was still bleeding actwely. It was then judged that no more heparin was circulating at that time, and it was decided that it would

Effect of intermittent warm blood cardioplegia on functional recovery after prolonged cardiac arrest

There is some evidence that continuous warm blood cardioplegia offers good myocardial protection; however, the effects of interrupting cardioplegia remain controversial. To study this, we compared the effects of continuous and intermittent antegrade warm (37 degrees C) blood cardioplegia on functional recovery after prolonged cardiac arrest (180 minutes). Twenty-four juvenile pigs were randomly assigned into four groups. Group 1 received continuous cardioplegia, group 2 underwent several periods of 15 minutes of cardioplegia interrupted by 5 minutes of normothermic ischemia, and group 3 underwent several periods of 10 minutes of cardioplegia interrupted by episodes of 10 minutes. The hearts of group 4 received no cardioplegia. Left ventricular systolic function was assessed from fractional left ventricular shortening and percentage left ventricular wall thickening, and left ventricular diastolic function was determined from the time constant of relaxation and the constant of myocardial stiffness. Systolic and diastolic functions were slightly depressed 1 and 2 hours after cross-clamp removal in all four groups, without significant differences among the groups. These data suggest that antegrade warm blood cardioplegia can be interrupted for up to 10 minutes without obvious negative effects on left ventricular function in the normal myocardium, provided that the intermittent doses of cardioplegia are sufficient to restore the metabolic demands of the arrested myocardium.

Intermittent antegrade warm blood cardioplegia in aortic valve replacement.

Intermittent antegrade warm blood cardioplegia (IAWBC) is a well established technique of myocardial protection for coronary artery surgery, with metabolic and experimental basis. To evaluate its effectiveness in aortic valve replacement (AVR), we compared 171 consecutive patients who underwent first AVR using IAWBC (group A) with the last 100 consecutive patients who underwent first AVR using intermittent antegrade cold blood cardioplegia (IACBC) (group B). The endpoints considered were myocardial protection related (recovery of spontaneous rhythm, need for mechanical support, incidence of low-output syndrome, perioperative Q wave myocardial infarct, CK-MB levels, ventricular arryhthmias and lidocaine infusion requirement, cardiac-related deaths, and deaths any cause) and temperature perfusion related (bleeding, awaking time, time to extubation, and cerebrovascular accidents). Mortality was similar in both groups, but no patient in group A died for cardiac-related cause (0 vs 4, p < 0.01). More patients in group A recovered a spontaneous rhythm (144 vs 47, p < 0.0001). Incidence of low-output syndrome was higher in group B (16 vs 3, p < 0.0005), as well as ventricular arryhthmias incidence and need for lidocaine infusion (respectively 15 vs 2, p < 0.0001, and 10 vs 1, p < 0.0005). Awaking time was shorter in warm patients (2.5 +/- 2.5 hours vs 4.4 +/- 3.7 hours, p < 0.0005), as the extubation time (9.4 +/- 7.7 hours vs 13.5 +/- 11.7 hours, p < 0.0005) and bleeding (803 +/- 714 mL/24 hours vs 1051 +/- 1375 mL/24 hours, p < 0.05). As a consequence, the intensive care unit and the postoperative hospital stays were shorter in group A (32 +/- 27 hours vs 48 +/- 20 hours, p < 0.0005, and 7.2 +/- 3.1 days vs 11.3 +/- 5.4 days, p < 0.0001, respectively). IAWBC provides lower cardiac-related mortality and morbidity in patients who undergo AVR in comparison with IACBC.