Right ventricular function: a comparison between blood and crystalloid cardioplegia

Blood cardioplegia resulted in better left ventricular (LV) function than crystalloid cardioplegia after elective coronary artery bypass operations. However, most methods of cardioplegic delivery may not adequately cool and protect the right ventricle, and right ventricular (RV) dysfunction may limit hemodynamic recovery. Therefore, RV and LV temperatures were measured intraoperatively and RV and LV function were evaluated postoperatively in 80 patients with double-vessel or triple-vessel coronary artery disease who were randomized to receive either blood cardioplegia or crystalloid cardioplegia. Myocardial performance, systolic function, and diastolic function were assessed with nuclear ventriculography by evaluating the response to volume loading. Preoperatively the groups were similar. Intraoperatively, blood cardioplegia resulted in significantly warmer LV and RV temperatures (left ventricle: 15.5 degrees +/- 0.2 degrees C with blood cardioplegia and 12.6 degrees +/- 0.3 degrees C with crystalloid cardioplegia [p less than .0001]; right ventricle: 18.3 degrees +/- 0.3 degrees C with blood cardioplegia and 15.1 degrees +/- 0.3 degrees C with crystalloid cardioplegia [p less than .0001]). Postoperatively, blood cardioplegia resulted in better LV performance (higher LV stroke work index at a similar LV end-diastolic volume index [EDVI]) (p = .01), better LV systolic function (similar systolic blood pressures at smaller LV end-systolic volume indexes [ESVI]), (p = .04), and improved LV diastolic function (lower left atrial pressures at similar LVEDVIs) (p = .03).(ABSTRACT TRUNCATED AT 250 WORDS)     

The Safety of Simultaneous Arterial and Coronary Sinus Perfusion: Experimental Background and Initial Clinical Results

Concern over myocardial damage from simultaneous arterial (antegrade) and coronary sinus (retrograde) perfusion has led to alternating between these delivery routes to maximize their individual benefits. Based upon predominant retrograde drainage via Thebesian veins, this study: (1) confirms experimentally the safety of simultaneous arterial and coronary sinus perfusion; and (2) reports initial clinical application of this combined strategy in 155 consecutive patients. Experimental: Five mini-pigs (25 to 30 kg) underwent 1 hour of aortic clamping with simultaneous aortic and coronary sinus perfusion at 200 mUmin with normal blood (37°C) before and after 30 minutes of perfusion with either warm (37°C) or cold (4°C) blood cardioplegia. Coronary sinus pressure was always less than 30 mmHg. There was no right or left ventricular edema, lactate production, or lipid peroxidation as transmyocardial and myocardial conjugated dienes were unaltered, and postbypass recovered left ventricular end-systolic elastance (conductance catheter) and preload recruitable stroke work Index 101%± 3% and 109%± 90%, respectively. Clinical: Simultaneous arteriaVcoronary sinus perfusion was used in 155 consecutive high risk patients (New York Heart Association Class III to IV) undergoing isolated coronary artery bypass grafting (CABG) (n = 109) and CABG + valve replacementlrepair or aneurysm (n = 46). Included were 16 patients in cardiogenic shock and 24 undergoing reoperation. Mean aortic clamping time averaged 90 ± 4 minutes (range 30 to 207), with 3.5 ± 0.1 grafts per patient; all anastomoses were performed with the aorta clamped. Cold intermittent blood cardioplegia was used for distal anastomoses and valve implantationhepair in 123 patients, and warm continuous blood cardioplegia was used in 32 patients. Following a warm cardioplegic reperfusate, all patients received warm non-cardioplegic blood perfusion simultaneously via grafts and coronary sinus. Coronary sinus pressure was always less than 40 mmHg. Of 18 patients requiring postoperative mechanical circulatory support (IABP), 16 had IABP placed preoperatively for cardiogenic shock. There were three postoperative myocardial infarctions (2%), and six patients died (3.9% mortality). Conclusion: These experimental and clinical findings overcome perceived concerns about myocardial damage from simultaneous arterial and coronary sinus perfusion, and suggest this approach may add to the armamentarium of cardioprotective strategies. (J Card Surg 1994;9:15–25)     

Myocardial metabolism and ventricular function following cold potassium cardioplegia

Transient alterations in myocardial metabolism and ventricular function were observed after elective coronary bypass grafting despite apparently adequate intraoperative protection with cold potassium cardioplegia. Ninety patients had serial hemodynamic measurements and coronary sinus catheters inserted. Thirty-three patients had thermodilution coronary sinus flow catheters inserted to measure coronary sinus blood flow and to evaluate the myocardial utilization of oxygen and lactate. Nuclear ventriculograms were performed in 43 patients to assess ventricular function. Cardiac index fell after discontinuation of cardiopulmonary bypass and then rose between 2 and 24 hours postoperatively. Myocardial oxygen consumption steadily increased during this period. Myocardial lactate production reverted to lactate extraction 30 minutes after reperfusion. Reactive hyperemia was present during the first 10 minutes after cross-clamp release, and coronary sinus blood flow increased gradually during the first 24 hours postoperatively. The response to the stress of volume loading (the infusion of 250 to 500 ml of a colloid solution) and atrial pacing (at a rate of 110 beats/min) was evaluated 2 to 4 hours postoperatively (EARLY) and between 4 to 6 hours postoperatively (LATE). Volume loading resulted in a decrease in lactate extraction EARLY and an increase LATE (EARLY: -0.07 +/- 0.35 mmol/L; LATE: 0.08 +/- 0.32 mmol/L, mean +/- standard deviation not significant). Atrial pacing resulted in a decrease in lactate extraction EARLY and an increase LATE (EARLY: -0.11 +/- 0.34 mmol/L; LATE: 0.14 +/- 0.36 mmol/L, p less than 0.05). Diastolic compliance (the relation between the end-diastolic volume index) decreased between EARLY and LATE. Systolic function (the relation between the systolic blood pressure and the end-systolic volume index) and myocardial performance (the relation between the left ventricular stroke work index and the end-diastolic volume index) were unchanged. Ejection fraction correlated inversely with the end-diastolic volume index and did not represent an independent index of contractility. After elective coronary bypass grafting and cold crystalloid cardioplegia, myocardial metabolism recovered slowly. Hemodynamic stresses should be avoided in the early postoperative period to prevent progressive ischemic injury.     

Does Simultaneous Antegrade and Retrograde Cardioplegia Improve Functional Recovery and Myocardial Homeostasis?

BACKGROUND: The purpose of our research was to evaluate the functional recovery and homeostasis of myocardium during simultaneous continuous retrograde and antegrade cardioplegia versus continuous retrograde cardioplegia. METHODS: Forty patients who underwent elective coronary artery bypass grafting (CABG) were prospectively assigned to two clinically matched groups and analyzed in respect to cardioplegia protocol. Group I consisted of 24 patients who received continuous retrograde blood cardioplegia; Group II consisted of 16 patients who received simultaneous continuous ante- and retrograde cardioplegia. Hydrogen ion release, carbon dioxide, lactate concentration oxygen content, and oxygen extraction were measured from coronary sinus effluent and from the arterial line before and after cross-clamping of the aorta. Median changes of these parameters were reported. Cardiac output was measured and left and right ventricle stroke works were calculated. Incidence of low cardiac output, ventricular fibrillation, raised cardiac enzymes, and ischemic changes on electrocardiogram (ECG) were noted. RESULTS: In the simultaneous group, oxygen content and oxygen extraction recovered well after cross-clamping. The same parameters did not recover to the same extent in the retrograde group. These changes were notable between groups. Hydrogen ion, carbon dioxide, and lactate releases were comparable between groups. Trend toward better recovery of left ventricle stroke work index was encountered in the simultaneous group. CONCLUSIONS: Viability of myocardium measured with oxygen utilization and functional recovery is better preserved with simultaneous antegrade and retrograde cardioplegia. However, there is no difference in anaerobic metabolism markers. Thus simultaneous ante- and retrograde cardioplegia is probably advantageous over retrograde alone.     

Diltiazem cardioplegia. A balance of risk and benefit

Calcium channel blockers may prevent myocardial injury during cardioplegia and reperfusion. A prospective, randomized trial was instituted to evaluate the hemodynamic and myocardial metabolic recovery in 40 patients undergoing elective aorta-coronary bypass with either diltiazem in crystalloid potassium cardioplegia (n = 20) or crystalloid potassium cardioplegia (n = 20). In a preliminary trial, doses between 150 and 250 micrograms/kg reduced the period of heart block after cross-clamp removal (90 +/- 110 minutes) from that found with higher doses and improved myocardial metabolism. In the randomized trial, diltiazem cardioplegia (150 micrograms/kg) produced coronary vasodilatation during cardioplegia and produced less reactive hyperemia during reperfusion. Myocardial oxygen extraction was lower and myocardial lactate production was less after diltiazem cardioplegia during reperfusion. Tissue adenosine triphosphate and creatine phosphate concentrations were preserved better after diltiazem cardioplegia. The postoperative creatine kinase MB levels were less (p less than 0.05) after diltiazem cardioplegia, which indicated less myocardial injury. Postoperative volume loading demonstrated that systolic function (the relation between systolic blood pressure and end-systolic volume index) was depressed after diltiazem cardioplegia compared to crystalloid cardioplegia, but cardiac index was higher because afterload (mean arterial pressure) was lower and preload (end-diastolic volume index) was higher. Diltiazem cardioplegia preserved high-energy phosphates, improved postoperative myocardial metabolism, and reduced ischemic injury after elective coronary bypass. However, diltiazem was a potent negative inotrope and produced prolonged periods of electromechanical arrest. Diltiazem cardioplegia may be of value in patients with severe ischemia but should be used with caution in patients with ventricular dysfunction, and a dose-response relation must be established at each institution before clinical use.     

Evaluation of the effects of coronary artery bypass grafting on left ventricular function in patients with previous myocardial infarction

The present study was designed to assess a left ventricular function following coronary artery bypass grafting (CABG) in patients with previous myocardial infarction (MI). The subject was consisted of 10 patients with MI (MI(+) group) and 6 without it (MI(-) group). Both groups underwent complete revascularization. Stroke index (SI), ejection fraction (EF), systolic pressure/end-systolic volume index (SP/ESVI) and end-diastolic volume index (EDVI) were evaluated utilizing radionuclide angiography at rest and during exercise (Ex) before and after CABG. The influence of size of myocardial infarction on left ventricular function were also analyzed. Preoperatively during Ex, EF showed decrease, SP/ESVI no change and EDVI increase in both MI(+) and MI(-) group compared with those at rest. Postoperatively during Ex, SI, EF and EDVI showed no change and SP/ESVI increase in both MI(+) and MI(-) group compared with those at rest. Ejection fraction and SP/ESVI during Ex in MI(+) group had significant differences compared with those in both MI(-) group and control group. Ejection fraction and SP/ESVI during Ex in MI(-) showed no difference compared with those in control group. The size of MI suggested by ECG scoring system (proposed by Wagner GS et al, Circulation '82) had negative correlations with both Ex-induced increment of postoperative EF and Ex-induced increase ratio of postoperative SP/ESVI. These data indicated that complete revascularization improved EF and SP/ESVI in patients with MI, and moreover normalized those in patients without MI. But in the case of extensive MI, even complete revascularization might not recover poor functional reserve during Ex.     

Effect of induction and reperfusion with warm substrate-enriched cardioplegia on ventricular function

BACKGROUND: This study tested the hypothesis that induction and reperfusion with warm substrate-enriched (IRWSE) blood cardioplegia improves postoperative left ventricular (LV) function in patients undergoing elective coronary bypass surgery (CABG). METHODS: After giving informed consent, 67 patients scheduled for CABG surgery were randomized to either IRWSE + cold blood (CB) or CB alone. IRWSE cardioplegia consisted of 37 degrees C substrate-enriched (glutamate, aspartate, hyperkalemic) anterograde and retrograde blood cardioplegic solution followed by non-substrate-enriched cardioplegic solution given at 4 degrees C to 8 degrees C. LV function was measured with ventriculograms, volume conductance catheters, echocardiography, and multiple gated (image) acquisition. RESULTS: The end-systolic pressure-volume relationship was improved postbypass in the IRWSE + CB group (CB, 1.5 +/- 0.74 mm Hg/mL vs IRWSE + CB, 2.1 +/- 1.2 mm Hg/mL; p = 0.042). The postoperative ejection fraction (EF%) was better preserved in the CB group (CB, 65 +/- 11.53% vs IRWSE + CB, 58.62 +/- 11.75%; p < 0.04). CONCLUSIONS: Our results demonstrate a transient improvement in LV systolic function in the immediate postbypass period in CABG patients in the IRWSE + CB group. The intraoperative benefits of the IRWSE + CB technique did not persist in the postoperative period.     

Coronary artery bypass grafting by warm blood cardioplegia and normothermic cardiopulmonary bypass

Warm blood cardioplegia and normothermic cardiopulmonary bypass (CPB) have been used in coronary artery bypass grafting (CABG). The method of myocardial protection was intermittent combined antegrade and retrograde warm blood cardioplegia with terminal warm blood cardioplegia. We performed elective CABG in 30 patients above the age of 70 years (elderly group). These patients were compared with 30 patients below 70 years who underwent elective CABG (young group). No significant differences were observed about the preoperative data between two groups. No significant differences were obtained in the postoperative cardiac function, cerebral or renal complication between two groups. Warm blood cardioplegia and normothermic CPB were not associated with adverse effects on postoperative recovery in elderly as well as young patients. We may conclude that warm blood cardioplegia with normothermic CPB is a safe procedure for CABG in elderly as well as young patients.     

Coronary sinus versus aortic root perfusion with blood cardioplegia in elective myocardial revascularization

The role of retrograde coronary sinus cardioplegia in patients undergoing elective coronary artery bypass grafting has not been fully defined. Forty patients undergoing coronary artery bypass grafting received either aortic root (20 patients) or coronary sinus (20 patients) cold potassium blood cardioplegia. The patients were similar with respect to age, ventricular function, severity of coronary artery disease, cross-clamp time, completeness of revascularization, frequency of internal mammary artery grafting, and mean infusate volume and temperature. The time required to deliver the initial dose of cardioplegic solution and the time to achieve arrest were prolonged in the coronary sinus group (p less than 0.001 and p less than 0.02, respectively). There were no differences between the two groups postoperatively with regard to enzymatic indices, hemodynamic measurement, or clinical outcome. Right ventricular function was preserved equally in both groups. We conclude that coronary sinus cardioplegia is a safe alternative to aortic root perfusion, but offers no advantage in elective myocardial revascularization.     

Myocardial cooling and right ventricular function in patients with right coronary artery disease: antegrade vs. retrograde cardioplegia

Background: Protection of the right ventricular (RV) myocardium during ischaemia in cardiac surgery is difficult, especially in patients with severe right coronary artery (RCA) disease. Retrograde coronary sinus cardioplegia is thought to distribute uniformly, but doubts still remain as to its adequacy in RV preservation. This study evaluated distribution of antegrade vs. exclusively retrograde coronary sinus cold blood cardioplegia by assessing myocardial cooling and compared the effects on RV function. Methods: Fifty-eight patients scheduled for elective coronary artery surgery - 29 patients with significant RCA disease and another 29 with no significant RCA stenosis (controls) - were randomised to receive either antegrade or retrograde cold blood cardioplegia through either aortic root or conventional self-inflating coronary sinus catheter (RCA-ante, RCA-retro, C-ante and C-retro groups). RV function was assessed by fast-response thermodilution. Myocardial temperatures were measured in the anterior and posterior wall of the right and left ventricle. Results: Cooling of the posterior wall of the RV was effective only in the control patients given antegrade cardioplegia (14.7°C), whereas in the other groups the lowest myocardial temperatures there remained above 20°C (RO.001). In patients with obstructed RCA both antegrade and retrograde cold cardioplegia led to uneven cooling of the myocardium. After cardiopulmonary bypass the RV ejection fraction (RVEF), RV stroke work index (RVSWI) and cardiac index (CI) were significantly reduced in the RCA-retro group, and RVSWI and CI in the C-retro group, too. Regression analysis showed an inverse relationship between the temperatures of the posterior walls of the ventricles and changes in the RVEF and CI. Conclusions: Retrograde and antegrade cardioplegia alone were not effective in reducing the temperature of the posterior wall of the RV in the patients with obstructed RCA, in whom with retrograde cardioplegia RV haemodynamics were impaired for 1 hour following bypass. Neither retrograde nor antegrade cardioplegia alone can be relied on to protect the posterior wall of the RV in the patients with obstructed RCA.     

Assessment of left ventricular contractile characteristics following coronary artery bypass grafting

The present study was designed to assess a left ventricular function, particularly contractile characteristics following coronary artery bypass grafting (CABG). The subject was 29 post-CABG patient consisting of 4 groups; 6 patients with complete revascularization (CR) and no myocardial infarction (MI) (CR.MI(-) group), with CR and MI (CR.MI(+) group), 5 with incomplete revascularization (IR) and no MI (IR.MI(-) group) and 8 with IR and MI (IR.MI(+) group). Ejection fraction (EF), systolic pressure/end-systolic volume index (SP/ESVI) and end-systolic volume index (EDVI) were evaluated utilizing radionuclide angiography at rest and during exercise (Ex). Increase of SP/ESVI and EF and no change of EDVI during Ex were observed in CR.MI(-) group. Increase of SP/ESVI and no change of EF and EDVI in CR.MI(+) group, no change of SP/ESVI, EF and EDVI in IR.MI(-) group and no change of SP/ESVI and EDVI and decrease of EF in IR.MI(+) group were observed. The SP/ESVI and EF of CR.MI(-) group were respectively highest among 4 groups and showed no difference compared with control group during Ex. Ex-induced increase ratio of SP/ESVI had linear correlations with Ex-induced increment of EF (r = 0.81, p less than 0.001) and Ex-induced increase ratio of EFVI (r = 0.54, p less than 0.005). It is concluded that both CR and no MI lead to normalization of EF and SP/ESVI during Ex. Furthermore, in the case of poor contractile reserve, systolic function may deteriorate in spite of increased preload during Ex.     

Normothermic cardiopulmonary bypass and cardioplegia reduce inotropic requirements and creatine kinase-MB after coronary artery bypass graft surgery

Purpose To determine whether normothermic cardiopulmonary bypass (CPB) and cardioplegia preserve myocardial function, reduce inotropic requirements, and reduce markers of myocardial ischemia following coronary artery bypass graft surgery (CABG). Methods We retrospectively reviewed the charts of 171 consecutive patients undergoing elective CABG by a single surgeon from April 1994 to December 1995. Hypothermic CPB with intermittent cold cardioplegia was used in 83 patients and normothermic CPB with intermittent warm cardioplegia in 88 patients. Demographic, surgical, hemodynamic, and inotropic requirements and laboratory data were reviewed. Results The duration of CPB was significantly shorter in the normothermic group (113±27vs 90±21 min;P<0.0001). After CPB the cardiac index was similar between groups, but significantly larger doses of both dopamine and dobutamine were required (8vs 5μg·kg⁻¹·min⁻¹,P<0.0001), and significantly more patients required norepinephrine administration in the hypothermic group (18%vs 6%;P=0.01). Postoperative peak values of creatine kinase MB fraction (CK-MB) were significantly lower in the normothermic group (80±60vs 55±54 IU·I⁻¹;P<0.0001). Conclusion Normothermic CPB and cardioplegia reduce inotropic requirements and CK-MB following CABG.     

Electrolyte versus Blood Cardioplegia: Randomized Clinical and Myocardial Ultrastructural Study

In 40 consecutive patients undergoing coronary artery bypass, one of two solutions for cardioplegia, each containing 30 mEq/L of K⁺ was used randomly. The groups were comparable except for intramyocardial temperature. With electrolyte solution (Group A), it was 16.5° ± 0.34°C, while with blood from the pump-oxygenator (Group B) it was 20.3° ± 0.41°C (p < 0.001). After bypass left atrial pressure (LAP) was 11.9 ± 0.67 torr in Group A and 8.1 ± 0.49 torr in Group B (p < 0.001). CPK-MB was elevated in 45% of Group A patients versus 15% in Group B (p < 0.05). No patient died. Two myocardial infarctions occurred in Group A and one in Group B. Stereological morphometric electron microscopy was performed on biopsy specimens taken from the left ventricle (1) before perfusion, (2) after cardioplegia, and (3) 30 minutes after reperfusion. Group A showed marked intracellular edema, mitochondrial swelling, pronounced depletion of glycogen stores, and focal myofibrillary disorganization. Group B showed near normal myocardial ultrastructure with increased glycogen stores and minimal mitochondrial swelling. Morphometric analysis revealed a statistically significant increase in the degree of mitochondrial swelling (51%) in Group A compared with Group B after reperfusion (p < 0.001). Thus, blood K⁺ cardioplegia resulted in better preservation of myocardial ultrastructure, lower ventricular filling pressure, and lesser CPK-MB release compared with this particular electrolyte cardioplegia.     

Comparison of Single versus Multidose Blood Cardioplegia in Arterial Switch Procedures

Fifty-three patients with transposition of the great arteries and Taussig-Bing anomaly undergoing an arterial switch procedure were divided into two groups. Group 1 (N = 32) received multidose cardioplegia injected initially into the aortic root and subsequently into the coronary artery orifices and Group 2 (N = 21), single-dose cardioplegia injected into the aortic root. The mean aortic cross-clamp and bypass times were generally longer in Group 1 compared with Group 2. Group 1 patients with simple transposition undergoing primary repair (N = 15) had an aortic cross-clamp time of 80 ± 8 minutes and a bypass time of 203 ± 27 minutes versus 64 ± 6 minutes (p < 0.001) and 170 ± 15 minutes (p < 0.01), respectively, for similar patients in Group 2 (N = 10). Group 1 patients with simple transposition undergoing staged repair (N = 7) had an aortic cross-clamp time of 71 ± 6 minutes and a bypass time of 201 ± 24 minutes versus 66 ± 4 minutes (p = not significant [NS]) and 226 ± 25 minutes (p = NS), respectively, for Group 2 (N = 6). In Group 1 patients with complex transposition (N = 10), the aortic bypass time was 79 ± 12 minutes and the bypass time was 261 ± 40 minutes versus 64 ± 11 minutes (p < 0.05) and 225 ± 16 minutes (p < 0.1), respectively, for Group 2 (N = 5). Early mortality was 16% (5/32) in Group 1; there were no early deaths in Group 2. One patient died of an occluded left coronary artery attributed to catheter trauma. Late mortality was 11% (3/27) in Group 1 and 5% (1/21) in Group 2. In Group 1, postoperative ST-T wave changes developed in 37% (10/27) compared with 5% (1/21) in Group 2. The postoperative myocardial performance determined echocardiographically by systolic increase in septal and posterior wall thickness, fractional shortening, and left ventricular end-diastolic dimensions was comparable in the two groups. We conclude that the administration of a single dose of cold blood cardioplegia into the aortic root, along with topical and systemic hypothermia, is a simple and effective method of myocardial protection in infants and young children undergoing the arterial switch procedure.     

Long term left ventricular systolic function assessment following CABG. A prospective, randomised study. Blood versus cristalloid cardioplegia

BACKGROUND: In an effort to define the role of blood cardioplegia delivered in antegrade/retrogade fashion in patients with either good or poor left ventricular function undergoing elective coronary artery bypass surgery, we initiated a prospective randomised study in which postoperative hemodynamics besides clinical data were compared in patients administered antegrade/retrograde crystalloid cardioplegia. METHODS: To compare the efficiency of two methods of myocardial protection--cold crystalloid ante/retro cardioplegia and cold blood ante/retro cardioplegia in two groups of patients with high and low LVEF--we randomised 122 patients for CABG. The potential improvement in left ventricular systolic function assessed by echocardiography and the same clinical data were the end points of the study. Patients were divided into group I (47 patients, LVEF <40%) and group II (75 patients, LVEF >40%). Pathologic antecedents and preoperative clinical conditions were similar in both randomised subgroups Ia, IIa (crystalloid cardioplegia) and subgroups Ib, IIb (blood cardioplegia). The following parameters were measured: left atrium diameter (LA), left ventricular end diastolic diameter (LVEDD), left ventricular end systolic diameter (LVESD), left ventricular ejection fraction (LVEF), left ventricular wall motion score index (WMSI), and area asynergy (AA). All patients underwent echocardiography: A--prior the CABG, B--2-6 weeks postoperatively, C--3 months postoperatively, D--6 months postoperatively, E--1 year postoperatively. RESULTS: The results of clinical assessment in both groups showed improvement of quality of life. The constant improvement of LVEF and WMSI was observed in group I in contrast to group II. There were no significant differences in postoperative left ventricular systolic function between subgroups Ia and Ib or IIa and IIb. CONCLUSIONS: The use of blood cardioplegia, instead of crystalloid cardioplegia, when used in the ante/retrograde fashion during CABG has no influence on postoperative left ventricular systolic function. The improvement in left ventricular systolic function following CABG is greater in patients with low LVEF in contrast to patients with high LVEF.     

Aortic valve replacement. Aortic root versus coronary sinus perfusion with blood cardioplegic solution.

The role of retrograde coronary sinus cardioplegia in patients undergoing aortic valve replacement for aortic stenosis alone or in combination with myocardial revascularization has not been fully defined. Sixty-three patients undergoing elective aortic valve replacement received cold potassium blood cardioplegic solution via either the aortic root (36 patients) or the coronary sinus (27 patients). The patients were similar with respect to age, degree of aortic stenosis, ventricular function, severity of coronary artery disease, crossclamp time, completeness of revascularization, and mean volume and temperature of the infusion solution. The mean septal temperature and the release of myocardium-specific isoenzyme in the first 2 hours after crossclamp removal was higher in the retrograde group (p less than 0.008). Right and left ventricular function was preserved equally in the two groups, and volume-loading studies suggested improved diastolic performance in patients having retrograde cardioplegia. There were no differences between the two groups with respect to clinical outcome. We conclude that coronary sinus cardioplegia is as safe as aortic root perfusion for myocardial preservation in patients undergoing elective aortic valve replacement.     

Terminal warm blood cardioplegia improves the recovery of myocardial electrical activity. A retrospective and comparative study.

OBJECTIVE: The effect of terminal warm blood cardioplegia was analyzed in 191 patients undergoing either coronary artery bypass grafting (CABG) or prosthetic heart valve replacement between Jan. 1990 and Dec. 1995. METHODS: Patients were subdivided into 3 historical cohorts based on the method of myocardial protection: Group A (n = 106), multidose cold crystalloid glucose-potassium cardioplegia, alone; Group B (n = 37), cold crystalloid glucose-potassium cardioplegia plus terminal warm blood cardioplegia, Group C (n = 48), cardioplegia induction with cold crystalloid glucose-potassium cardioplegia, maintenance with multidose cold blood cardioplegia, and terminal warm blood cardioplegia. RESULTS: Of patients undergoing CABG, 5.6% of group A, 70.4% of group B, and 86.7% of group C spontaneously resumed sinus rhythm after aortic declamping, as did 9.1% of group A, 60.0% of group B, and 55.6% of group C of patients undergoing prosthetic heart valve replacement. The incidence of spontaneous recovery was significantly better in groups B and C than in group A (p < 0.05). Over 90% of patients without terminal warm blood cardioplegia developed ventricular fibrillation or tachycardia requiring electrical cardioversion (p < 0.05). Postoperatively, patients without terminal warm blood cardioplegia required temporary epicardial pacing more frequently than those with terminal warm blood cardioplegia (p < 0.05). In patients undergoing prosthetic heart valve replacement, groups B and C, the incidence of postoperative atrial fibrillation was significantly lower than in group A. CONCLUSION: Terminal warm blood cardioplegia thus promoted better postoperative electrophysiological cardiac recovery.     

Retrograde versus antegrade cardioplegia: impact on right ventricular function.

Retrograde cardioplegia administered through the coronary sinus has several documented advantages over antegrade cardioplegia but has been thought to provide inadequate right ventricular myocardial protection. We prospectively compared the effects of retrograde and antegrade cardioplegia on right ventricular performance in patients undergoing myocardial revascularization. Two groups of similar age, extent of disease, and preoperative left ventricular ejection fraction received retrograde (n = 16) or antegrade (n = 14) crystalloid cardioplegia. A right ventricular rapid-response thermistor catheter, previously developed and validated in our institution, was used to measure right atrial pressure, pulmonary artery pressure, right ventricular ejection fraction, end-diastolic volume index, and stroke volume index before bypass (baseline) and at several intervals after bypass. There were no differences in cross-clamp time, heart rate, cardiac enzymes, inotrope requirements, or arrhythmias between the two groups. Right ventricular parameters were equivalent in both groups at all time intervals except 30 minutes after bypass, at which time right ventricular end-diastolic volume index was lower (80 +/- 6 versus 93 +/- 6 mL/m2; p less than 0.05) and right ventricular stroke volume index was higher (35 +/- 3 versus 29 +/- 2 mL/m2, p less than 0.05) in the retrograde group compared with the antegrade group, indicating better right ventricular function with retrograde cardioplegia early after bypass. In both groups, right ventricular end-diastolic volume index was higher than baseline (p less than 0.05) during the first 4 hours after bypass. No other important differences were found.(ABSTRACT TRUNCATED AT 250 WORDS)     

Changes in left ventricular volume and predictors of cardiac events after endoventricular circular patch plasty

Objective: The aim of this study was to identify predictors of cardiac events after endoventricular circular patch plasty (Dor operation) by analyzing our experience with Dor operation. Methods: Thirty patients with left ventricular aneurysm and/or ischemic cardiomyopathy who underwent Dor operation were included in this study. Hemodynamic and clinical results were analyzed, and the predictors of cardiac events were examined. Results: Hospital mortality was 3.3%. Postoperative clinical status and left ventricular (LV) function in all survivors significantly improved. The survival rates at 1, 3, and 5 years after operation were 93%, 89% and 89%. The corresponding cardiac event-free rates were 75%, 67% and 49%. Pre- and postoperative LV function and volume did not differ significantly between patients with or without cardiac events. However, the proportion of reduced end-diastolic volume index (EDVI) (preoperative EDVI-postoperative EDVI) to preoperative EDVI was significantly higher in patients with cardiac events than in cardiac event-free patients. Postoperative LV volume re-increased in the cases with cardiac events during follow-up. Cox regression analysis confirmed that preoperative clinical premature ventricular contraction and end-systolic volume index (ESVI), postoperative EDVI, ESVL and ejection fraction were independent predictors of late cardiac events. There was a significant positive correlation between preoperative ESVI and postoperative EDVI. Conclusion: Though LV function significantly improved after Dor operation, LV reconstruction with excessive reduction can cause restarting LV remodeling and increasing mortality and morbidity. Therefore, LV reconstruction of appropriate sizes and shapes, considering the function of residual myocardium, has a significant effect on prognosis. It is highly reasonable to expect that preoperative ESVI can predict the optimal size of reconstructed left ventricle. Read at the Fifty-sixth Annual Meeting of the Japanese Association for Thoracic Surgery, Panel Discussion, Tokyo, November 19–21,2003.     

MRI评估不同手术阶段功能性单心室心功能

目的用核磁共振影像（MRI）测定不同手术阶段功能性单心室（FSV）心功能,探讨心功能变化原因及相关因素.方法2004年4月至2004年11月,41例FSV病儿分3组行MRI检查：Ⅰ组（未手术者）24例;Ⅱ组（双向腔肺动脉吻合术,BCPC后）9例;Ⅲ组（全腔肺动脉吻合术,TCPC后）8例.6名健康儿为对照.比较各组舒张末容量指数（EDVI）、收缩末容量指数（ESVI）、心搏指数（SVI）、心肌质量指数（MassI）、心指数（CI）、EF和Mass/EDV.结果Ⅰ组和Ⅱ组的EDVI和ESVI显著大于对照;Ⅰ组SVI显著大于Ⅲ组和对照;Ⅰ组CI显著大于其他组;Ⅱ组和Ⅲ组EF显著小于对照;前三组MassI显著大于对照;Ⅲ组Mass/EDV显著大于其他组.结论FSV术前心功能表现与此期血流动力学处于高负荷状态一致.BCPC术和TCPC术后中远期心脏舒缩功能不全与舒张末期容量和心肌质量异常有关.MRI评价FSV心功能更具优势.