New concept in coronary angioplasty: dilatation with a helical balloon that allows simultaneous autoperfusion

OBJECTIVE: This study was done to determine whether retrograde delivery of cardioplegic solution provides uniform blood flow to the myocardium supplied by an occluded coronary artery and whether it maintains myocardial energy levels beyond the coronary occlusion. METHODS: Isolated pig hearts were used. A hydraulic occluder was placed at the origin of the left anterior descending coronary artery. The perfusion pressure for retrograde delivery of cardioplegic solution was controlled at 40 to 50 mm Hg. Magnetic resonance imaging and localized 31P magnetic resonance spectroscopy were used to assess myocardial perfusion and energy metabolism, respectively. RESULTS: Magnetic resonance perfusion images (n = 7) showed that the perfusion defect that occurred during antegrade delivery of cardioplegic solution (as a result of the occlusion of the left anterior descending coronary artery) resolved during retrograde delivery of cardioplegic solution. Retrograde perfusion delivered similar amounts of flow to the jeopardized myocardium as it did to other areas of the myocardium. However, the distribution of cardioplegic solution by the retrograde route was heterogeneous (cloudlike) across both ventricular walls. 31P magnetic resonance spectra showed that the ischemic changes induced by occlusion of the left anterior descending artery during antegrade perfusion were greatly alleviated by retrograde perfusion; however, it took longer for retrograde cardioplegia (n = 7, 17.08 minutes) to restore the levels of inorganic phosphate/phosphocreatine relative to the effect of releasing the left anterior descending artery occluder during antegrade delivery of cardioplegic solution (n = 7, 5.3 minutes). CONCLUSIONS: First, retrograde delivery of cardioplegic solution provides sufficient flow to the myocardium beyond a coronary occlusion to maintain near normal levels of energy metabolites, and second, the efficacy of the retrograde route of cardioplegic solution delivery (in terms of distribution of the solution and rate of myocardial energy recovery) is significantly lower than that of the antegrade route.     

Crystalloid cardioplegia route of delivery and cardiac troponin I release

BACKGROUND: Cardiac troponin I (CTn I) has been shown to be a marker of myocardial injury. Incomplete distribution of cardioplegic solution may be responsible for injury in jeopardized myocardial areas. The aim of this study was to compare CTn I release with respect to the route of delivery of crystalloid cardioplegia, either antegrade only or initially antegrade followed by retrograde cardioplegia for the remainder of the operation, in patients undergoing elective coronary artery bypass grafting. METHODS: Sixty patients were randomly assigned to one of two cardioplegia groups. Cardiac troponin I concentrations were measured in serial venous blood samples drawn just before cardiopulmonary bypass and after aortic unclamping at 6, 9, 12, and 24 hours and daily thereafter for 5 days. Analysis of variance with repeated measures was performed to test the effect of route of delivery, coronary disease, collateral circulation, risk of cardioplegia maldistribution, and number of grafts on release of CTn I. RESULTS: Compared with the antegrade route, the combined route offered no advantage in an unselected group of patients undergoing an elective first cardiac operation and having preserved left ventricular function. The CTn I concentration did not differ between groups for any of the samples considered. In patients with major left main coronary artery stenosis, CTn I release was significantly higher at hour 9 in the antegrade group than in the group with combined delivery. CONCLUSIONS: A combined route of delivery of crystalloid cardioplegia is beneficial in patients with major stenosis of the left main coronary artery. Cardiac troponin I sensitivity is relevant in this study. Release of CTn I should be useful in determining the best form of myocardial protection for each patient.     

Retrograde perfusion as a method for myocardial revascularization

Retroperfusion of the superficial coronary venous system was studied in 44 canine fibrillating in vivo, normothermic preparations, with exclusion of the systemic circulation using cardiopulmonary bypass techniques in order to assess its value as a method of myocardial revascularization. Perfusion of either the isolated aortic arch via a brachiocephalic cannula or of the coronary sinus through the free end of a vein anastomosed to the atrial rim of the sinus was performed for 1 h at 100 cm3/min in groups II-IV following 30 min of anoxia. Oxygen uptake, vascular resistance, venous outflow and venous enzyme levels (CPK, GDH) were studied. Group I controls (antegrade perfusion, no anoxia) showed continued aerobic metabolism in contrast to group II (antegrade perfusion) and III (retrograde perfusion) which displayed negative lactate balance. Oxygen consumption was greater in group III than II (p less than 0.01) with a higher oxygen extraction in III (p less than 0.005). Group IV, which was given intravenously 30 mg/kg methylprednisolone prior to anoxia and then retroperfused, showed continued aerobic metabolism with low GDH venous levels and adequate oxygen consumption. Three dogs were then subjected to aortoatrial rim coronary sinus vein grafts with ligation of the left common coronary artery at its bifurcation with distal left circumflex and anterior descending artery-internal mammary vein anastomoses for venous drainage. The right coronary artery was left intact. Arterial inflow into the coronary sinus was associated with a left ventricular pressure of 70-80 mm Hg for up to 1.5 h while regular sinus rhythm was maintained. We conclude that retroperfusion of the coronary sinus represents a surgically feasible technique for providing oxygen delivery to the ischemic myocardium.     

Antegrade or retrograde blood cardioplegic method: comparison of postsurgical right ventricular function and conduction disturbances

This study was undertaken to compare postsurgical right ventricular function and the occurrence of conduction disturbances after employing cold blood antegrade or retrograde cardioplegia during open heart surgery. Thirty-four patients were divided into AC (antegrade) and RC (retrograde) groups for the difference of route for delivery of cardioplegic solutions. Preoperative evaluation of cardiac and respiratory function revealed to be equal characteristics between the groups. Postoperatively, A-aDO2 and respiratory index (RI) as functional parameters of oxygenation capacity, LVSWI, RVSWI, dosage of dopamine and conduction disturbances were monitored at 0, 3, 6, 12 hours after termination of cardiopulmonary bypass and at extubation period. Although the recovery of respiratory function and left ventricular function were similar in both groups, temporal suppression of right ventricular function was indicated in RC group during early period after surgery, and then recovered to the same values of AC group within 3 hours. In RC group, several type of conduction disturbances were detected in 28 per cent of patients. But none of the persistent conduction disturbances were remained in all patients. We suggest retrograde coronary sinus perfusion may emerge as a valuable alternative to antegrade methods for delivery of cardioplegia.     

The versatility of anterograde/retrograde cardioplegia in heart surgery

Eighty patients underwent open-heart surgery from March 1990 to March 1993. We used combined aortic root (antegrade)/coronary sinus (retrograde) perfusion for cardioplegia delivery as a means of myocardial protection. The special retroplegia cannula was introduced to the coronary sinus (CS) in 67 patients by the transatrial (blind intubation) after one cannula cava insertion; the CS was cannulated under direct vision by right atriotomy after bicaval cannulation in 13 patients. Varied and prolonged cardiac procedures were done using cooled crystalloid cardioplegia (4 centigrades + potassium) except in one patient with severe ventricular damage in whom warm blood cardioplegia was infused. There was no CS or cardiac vein damage or disruption. There was no A-V blockade. The CS was intubated easily in all cases and cardioplegia solution readily infused. Coronary sinus pressure never exceeded 40 mm Hg. Overall hospital mortality (30 days postoperative) was 3.75% (3 cases). Sepsis was the cause of death in 2 patients and stroke in one. Inotropes were used in few cases as a means of renal protection. We conclude that the combined antegrade/retrograde cardioplegia delivery can be used routinely in most patients undergoing open-heart surgery.     

Effects of intraaortic balloon pumping on septal arterial blood flow velocity waveform during severe left main coronary artery stenosis

OBJECTIVES: We sought to evaluate the effect of intraaortic balloon pumping on the phasic blood velocity waveform into myocardium with severe coronary artery stenosis. BACKGROUND: In the presence of severe coronary artery stenosis, it is not clear whether intraaortic balloon pumping augments intramyocardial inflow during diastole or changes systolic retrograde blood flow from the myocardium to the extramural coronary arteries. METHODS: Using anesthetized open chest dogs (n=7), we introduced severe stenosis in the left main coronary artery to reduce the poststenotic pressure to approximately 60 mm Hg (>90% diameter stenosis). Septal arterial blood flow velocities were measured with a 20-MHz, 80-channel ultrasound pulsed Doppler velocimeter. Left anterior descending arterial flow, aortic pressure and poststenotic distal coronary pressure were measured simultaneously. The diastolic anterograde flow integral and systolic retrograde flow integral were compared in the presence and absence of intraaortic balloon pumping. RESULTS: Although intraaortic balloon pumping augmented diastolic aortic pressure, this pressure increase was not effectively transmitted through stenosis. Septal arterial diastolic flow velocity was not augmented, and left anterior descending arterial flow was unchanged during intraaortic balloon pumping. CONCLUSIONS: In the presence of severe coronary artery stenosis, intraaortic balloon pumping failed to increase diastolic inflow in the myocardium and did not enhance systolic retrograde flow from the myocardium to the extramural coronary artery. Thus, the major effect of intraaortic balloon pumping on the ischemic heart with severe coronary artery stenosis may be achieved by reducing oxygen demand by systolic unloading.     

Perfusion of ischemic myocardium during anesthesia with sevoflurane

BACKGROUND: Sevoflurane produces direct vasodilation of coronary arteries in vitro and decreases coronary vascular resistance in vivo, pharmacologic properties that may contribute to the development of "coronary steal." This investigation examined the effects of sevoflurane on the distribution of regional myocardial perfusion in chronically instrumented dogs with steal-prone coronary artery anatomy. METHODS: Dogs were chronically instrumented for measurement of aortic and left ventricular pressure, diastolic coronary blood flow velocity and subendocardial segment length. After recovery from surgery, dogs underwent repetitive, brief, left anterior descending coronary artery (LAD) occlusions via an implanted hydraulic vascular occluder to enhance collateral development. A progressive left circumflex coronary artery (LCCA) stenosis was also obtained using an ameroid constrictor. After development of LCCA stenosis, the LAD was totally occluded to produce a model of multivessel coronary artery disease. Systemic hemodynamics, regional contractile function and myocardial perfusion measured with radioactive microspheres were assessed in the conscious state and during sevoflurane anesthesia at 1.0 and 1.5 MAC with and without restoration of arterial blood pressure and heart rate to conscious levels. RESULTS: Total LAD occlusion with simultaneous LCCA stenosis increased heart rate, mean arterial pressure, left ventricular systolic and end-diastolic pressures, end-diastolic segment length, and rate-pressure product in conscious dogs. Subsequent administration of sevoflurane caused dose-related decreases in arterial pressure, left ventricular systolic pressure, double product, and peak rate of increase of left ventricular pressure at 50 mmHg. Perfusion of normal myocardium was unchanged during sevoflurane anesthesia. In contrast, sevoflurane caused dose-dependent decreases in blood flow to myocardium supplied by the stenotic LCCA, which returned to control levels after restoration of heart rate and arterial pressure. No reduction in collaterally derived blood flow to the occluded region was produced by 1.0 or 1.5 MAC sevoflurane. No redistribution of blood flow away from the occluded LAD region to normal or stenotic myocardium occurred during sevoflurane anesthesia. In fact, increases in the ratio of blood flow between occluded and normal zones or occluded and stenotic zones were observed in the subepicardium during 1.5 MAC sevoflurane with maintenance of the heart rate and arterial pressure at conscious levels. CONCLUSIONS: The results demonstrate that sevoflurane does not reduce or abnormally redistribute myocardial blood flow derived from coronary collateral vessels in a chronically instrumented canine model of multivessel coronary artery obstruction.     

Coronary collateral circulation behaviour and myocardial viability in chronic total occlusion treated with coronary angioplasty

AIMS: We explored the role of microcirculation integrity following the chronic occlusion of an infarct-related artery to assess the behaviour of collateral circulation during and after reperfusion by coronary angioplasty METHODS AND RESULTS: Eighteen patients with a proximally occluded left anterior descending artery and firm evidence of intercoronary collateral circulation were studied with selective coronary angiography and selective intracoronary myocardial contrast echocardiography, before coronary angioplasty, and at 5 and 15 min and 12 h later. Myocardial enhancement during myocardial contrast echocardiography was evaluated with a semiquantitative score (0-3), which was correlated to basal and 6 months' regional left ventricular wall motion results. 16/18 procedures were successfully performed; four patients with an inadequate acoustic window were excluded. Restenosis was evident at the 6 months' follow-up in two patients. Basal myocardial contrast echocardiography indicated that 81/192 segments from the left anterior descending coronary artery and 90/192 from the right coronary artery were perfused; no perfusion was observed in 21 segments either before or after coronary angioplasty. After coronary angioplasty, the angiographic intercoronary collateral circulation immediately disappeared, and myocardial contrast echocardiography revealed that there was a progressive reduction of segments perfused by the right coronary artery and an increase in segments perfused by the left anterior descending coronary artery. Regional left ventricular wall motion analysis demonstrated that there was abnormal motion in 51/192 segments. There was no improvement in segments with score 0 and abnormal motion after 6 months (100% sensitivity), but 16/17 segments with score 3 did show an improvement (98% specificity). The predictive value of intermediate scores (1-2) in detecting long-term improvement, was only 43%. CONCLUSION: These data show that the adaptive mechanism observed in the behaviour of epicardial and microvascular circulation after reperfusion of a chronic occluded infarct-related artery can vary. In addition, this study clearly shows that microvascular integrity detected by myocardial contrast echocardiography can provide myocardial viability.     

Evaluation of 7,000+ patients with two different routes of cardioplegia

BACKGROUND: This study examined the efficacy and safety of retrograde cardioplegia in comparison with an antegrade/retrograde approach. METHODS: Between January 1, 1991, and December 31, 1995, 7,032 coronary artery bypass procedures, alone or in combination with valve replacement/repair, were performed using either retrograde cardioplegia (R) or an antegrade/retrograde (AR) approach. There were 4,224 patients in the R group and 2,808 in the AR group. These included elective, urgent, emergent/salvage, first operative, and redo cases. RESULTS: All preoperative, intraoperative, and postoperative variables listed in The Society of Thoracic Surgeons National Cardiac Surgery Database were used to compare the two groups using univariate analysis. The pump time was longer in the AR group, with fewer grafts per patient. The R group had higher predicted risk (3.2% versus 3.0%; p = 0.04), more postoperative atrial fibrillation (34% versus 31%; p = 0.006), and longer postoperative length of stay (8.8 versus 8.0 days; p < 0.001). Using The Society of Thoracic Surgeons National Cardiac Surgery Database predicted risk group model, a subgroup of 221 coronary artery bypass grafting patients in the retrograde (s-R) and 132 coronary artery bypass grafting patients in the antegrade/retrograde (s-AR) group fell into a greater incidence of predicted mortality group (> or = 10%). The s-R subgroup had more patients in New York Heart Association functional class IV. Univariate analysis revealed higher postoperative atrial fibrillation (51% versus 41%; p = 0.05) and longer postoperative length of stay (12.8 versus 10.8 days; p = 0.03) in the s-R subgroup versus the s-AR subgroup. CONCLUSIONS: The results appear to favor neither approach. Preoperatively, both retrograde groups (R and s-R) had higher preoperative predicted risk, but operative mortality or complications were not significantly increased when compared with the AR and s-AR groups. Retrograde cardioplegia alone was shown to be effective in the R and s-R groups, but atrial fibrillation developed in more patients, which could have contributed to longer length of stay in these groups. Antegrade/retrograde cardioplegia offers good immediate outcome but the delivery method can be cumbersome and confusing during the adjustments of flow clamps for antegrade/retrograde delivery and may contribute to prolonged pump times. From this retrospective, nonrandomized review, it appears that retrograde cardioplegia alone provides as good myocardial protection and safety as an antegrade/retrograde approach in either the low-risk or high-risk patient.     

Ischemic preconditioning attenuates postischemic coronary artery endothelial dysfunction in a model of minimally invasive direct coronary artery bypass grafting

OBJECTIVE: Unmodified reperfusion without cardioplegia in minimally invasive direct coronary artery bypass grafting procedures causes endothelial dysfunction that may predispose to polymorphonuclear neutrophil-mediated myocardial injury. This study tested the hypothesis that ischemic preconditioning in a minimally invasive direct coronary artery bypass grafting model attenuates postischemic endothelial dysfunction in coronary vessels. METHODS: In anesthetized dogs, the left anterior descending coronary artery was occluded for 30 minutes and reperfused for 3 hours without ischemic preconditioning (no-ischemic preconditioning; n = 7); in 7 dogs, the left anterior descending occlusion was preceded by 5 minutes occlusion followed by 5 minutes of reperfusion. Relaxation responses to stimulators of nitric oxide synthase were used to evaluate endothelial function in arteries from the ischemic-reperfused (left anterior descending) and nonischemic (left circumflex coronary artery) zones. RESULTS: Stimulated endothelial-dependent relaxation of epicardial left anterior descending artery to incremental concentrations of acetylcholine in the no-ischemic preconditioning animals was shifted to the right, and maximal relaxation was attenuated compared with the nonischemic left circumflex coronary artery (117% +/- 4% vs 138% +/- 5%). In contrast, acetylcholine-induced maximal relaxation was comparable in the left anterior descending artery versus left circumflex coronary artery in the ischemic preconditioning group (130% +/- 6% vs 135% +/- 5%). In 150- to 200- microm left anterior descending microvessels, 50% relaxation occurred with a lower concentration (log[M]) of acetylcholine in ischemic preconditioning versus no-ischemic preconditioning (-8.0 +/- 0.4 vs -7.0 +/- 0.1) with no group differences in smooth muscle relaxation to sodium nitroprusside, suggesting endothelial-specific damage. Adherence of fluorescent labeled polymorphonuclear neutrophils to epicardial coronary artery endothelium, used as an index of basal (unstimulated) anti-polymorphonuclear neutrophil function, was significantly attenuated by ischemic preconditioning versus no-ischemic preconditioning (293 +/- 25 polymorphonuclear neutrophils/mm2 vs 528 +/- 29 polymorphonuclear neutrophils/mm2). CONCLUSION: In this minimally invasive direct coronary artery bypass grafting model, both agonist-stimulated and basal postischemic endothelial dysfunction were attenuated by ischemic preconditioning.     

Effects of cold and warm blood cardioplegia assessed by myocardial pH and release of metabolic markers

The optimal temperature of blood cardioplegia remains controversial. Interstitial myocardial pH was monitored online with a probe that was inserted in the anterior wall of the left ventricle. Venous pH, lactate production, and creatine kinase and troponin T release were measured in coronary sinus blood obtained in 14 dogs after ischemic arrest periods of 5, 10, 20, and 40 minutes with warm (n = 7; mean myocardial temperature, 35 degrees +/- 2 degrees C) and cold (n = 7; mean myocardial temperature, 12 degrees +/- 1 degree C) blood cardioplegic protection. Blood cardioplegic solution was delivered at a rate of 100 mL/min during the 10 minutes between each ischemic arrest. The interstitial myocardial pH decreased significantly (p < 0.05) from 7.1 +/- 0.3 to 6.53 +/- 0.3 after ischemia in animals perfused with warm blood cardioplegia and from 7.04 +/- 0.3 to 6.64 +/- 0.1 in those receiving cold blood cardioplegic protection; however, the difference between the groups was not significant (p > 0.05). Lactate production and creatine kinase and troponin T release increased significantly after ischemia, but there was no difference in the changes between the warm and cold blood cardioplegia groups. In conclusion, ischemia caused significant changes in all variables measured, and these changes were directly proportional to the duration of ischemia. However, there was no significant difference (p > 0.05) in the myocardial metabolic changes between the warm and cold blood cardioplegia groups in terms of the duration of ischemic arrest studied.(ABSTRACT TRUNCATED AT 250 WORDS)     

Two cases of total arch replacement after coronary artery bypass surgery with internal mammary artery graft

We report two successful cases of total arch replacement after coronary artery bypass surgery (CABG) using internal mammary artery graft (ITA). Case 1 had a true aneurysm of the distal aortic arch occurring 7 years after CABG using left ITA, and case 2 had a dissecting aneurysm of DeBakey II occurring 10 months after CABG using right ITA. This patient was also complicated by a preexisting true aneurysm of the proximal descending aorta. Both cases were managed by repeat midsternal incision, selective cerebral perfusion (SCP) and retrograde cardioplegia. In both cases, functioning ITAs were dissected out easily without injury, and an operative filed for total arch replacement was well obtained under the cardioplegia and brain protection mentioned above.     

Closed-chest cardiopulmonary bypass and cardioplegia: basis for less invasive cardiac surgery

BACKGROUND: We developed a method of closed-chest cardiopulmonary bypass to arrest and protect the heart with cardioplegic solution. This method was used in 54 dogs and the results were retrospectively analyzed. METHODS: Bypass cannulas were placed in the right femoral vessels. A balloon occlusion catheter was passed via the left femoral artery and positioned in the ascending aorta. A pulmonary artery vent was placed via the jugular vein. In 17 of the dogs retrograde cardioplegia was provided with a percutaneous coronary sinus catheter. RESULTS: Cardiopulmonary bypass time was 111 +/- 27 minutes (mean +/- standard deviation) and cardiac arrest time was 66 +/- 21 minutes. Preoperative cardiac outputs were 2.9 +/- 0.70 L/min and postoperative outputs were 2.9 +/- 0.65 L/min (p = not significant). Twenty-one-French and 23F femoral arterial cannulas that allowed coaxial placement of the ascending aortic balloon catheter were tested in 3 male calves. Line pressures were higher, but not clinically limiting, with the balloon catheter placed coaxially. CONCLUSIONS: Adequate cardiopulmonary bypass and cardioplegia can be achieved in the dog without opening the chest, facilitating less invasive cardiac operations. A human clinical trial is in progress.     

Myocardial protection during antegrade versus retrograde cardioplegia

BACKGROUND: It has been suggested that the right ventricular myocardium is suboptimally protected during retrograde blood cardioplegia. METHODS: Twenty patients undergoing an elective coronary bypass procedure were randomized to receive antegrade or retrograde mild hypothermic blood cardioplegia. Transventricular differences in oxygen extraction, lactate production, and pH were monitored during aortic cross-clamping, and myocardial biopsy specimens were taken from both ventricles before cannulation and 15 minutes after aortic declamping for analysis of adenine nucleotides and their breakdown products. The extent of myocardial injury was estimated by monitoring postoperative leakage of troponin T and the MB isoenzyme of creatine kinase. Hemodynamic recovery and postoperative complications were noted. RESULTS: The preoperative characteristics of the two groups were similar. Oxygen extraction and lactate production in the right ventricular myocardium were higher in the retrograde group. In this group, the right ventricle also extracted more oxygen and produced more lactate and acid than did the left ventricle. Tissue levels of adenine nucleotides tended to decrease in both ventricles during operation, with no differences between them. The level of adenosine catabolites did increase somewhat in the right ventricular myocardium of the retrograde cardioplegia group after aortic declamping. There was a tendency for more prominent efflux of troponin T and the MB isoenzyme of creatine kinase in the retrograde group. Nevertheless, the postoperative course was uneventful in both groups. CONCLUSIONS: Retrograde mild hypothermic blood cardioplegia leads to metabolic changes compatible with right ventricular ischemia. Nevertheless, tissue levels of high-energy phosphates are well preserved, and the postoperative course seems to be unproblematic. Care should be taken when retrograde normothermic blood cardioplegia is provided for patients with right ventricular hypertrophy, poor right ventricular function, or severe preoperative myocardial ischemia.     

Ischemic preconditioning prior to myocardial protection with cold blood cardioplegia in coronary surgery

OBJECTIVE: Encouraging results on myocardial preconditioning in experimental models of infarction, stunning or prolonged ischemia raise the question whether preconditioning techniques may enhance conventional cardioplegic protection used for routine coronary surgery. METHODS: A prospective clinical trial was conducted to investigate the effect of additional ischemic normothermic preconditioning prior to cardioplegic arrest applying cold blood cardioplegia in patients scheduled for routine coronary surgery (3 vessel disease, left ventricular ejection fraction > 50%). Two cross clamp periods of 5 min with the hearts beating in sinus rhythm were applied followed by 10 min of reperfusion, each (n = 7, group I). Inducing moderate hypothermia cold blood cardioplegia was delivered antegradely. In control groups, cold intermittent blood cardioplegia (n = 7, group II) was used alone. Coronary sinus effluents were analyzed for release of creatine kinase (CK), CK-MB, lactate, and troponin T at 1, 3, 6, 9, and 12 h. In addition, postoperative catecholamine requirements were monitored. RESULTS: The procedure was tolerated well, and no perioperative myocardial infarction in any of the groups studied occurred. Concentrations of lactate tended to be higher in group I, but this difference was not significant. In addition, no significant differences for concentrations of CK, CK-MB, and troponin T were found. Following ischemic preconditioning an increased dosage of dopamine was required within the first 12 h postoperatively (group I: 2.63 +/- 1.44 microg/kg/min, group II: 0.89 +/- 1.06 microg/kg/min). CONCLUSIONS: Combining ischemic preconditioning and cardioplegic protection with cold blood cardioplegia does not appear to ameliorate myocardial protection when compared to cardioplegic protection applying cold blood cardioplegia alone. Inversely, contractile function seemed to be impaired when applying this protocol of ischemic preconditioning.     

Sudden death in cases with anomalous origin of the left coronary artery

Ectopic origin of the left coronary artery from the right sinus of valsalva with anterior and posterior courses are thought to be benign anomalies. Case reports: a 58-year-old woman died suddenly after a car accident without having sustained any injuries. The only abnormal finding was an ectopic origin of the left coronary artery from the right sinus with anterior free wall course. The anomaly was complicated by the absence of a left descending branch and a hypoplastic circumflex artery. A 38-year-old male died suddenly during work. Beside the ostium of the right coronary artery originated the normal calibered circumflex branch of the left coronary artery which passed behind the aorta. The left anterior descending branch had a normal origin. There was a 2 cm in diameter transmural infarct observed microscopically.     

Experimental application of synchronized coronary sinus retroperfusion (SCSR) and left heart bypass (LHB) for severe cardiogenic shock

In order to evaluate the efficacies of concomitant use of left heart bypass (LHB) and synchronized coronary sinus retroperfusion (SCSR) for ischemic cardiogenic shock refractory to conventional mechanical circulatory assist such as intra-aortic balloon pumping (IABP), experimental comparison studies were made in swine. The acute myocardial infarction model was made by left anterior descending coronary artery (LAD) ligation method. LHB was performed by centrifugal pump (BioMedicus BP-80), supporting flows of half cardiac output. SCSR catheter was inserted into coronary sinus (CS) through external jugular vein. Then arterial blood was pumped from femoral artery to CS with flow of 60 to 70 ml/min which was synchronized to electrocardiogram (ECG). These animals were supported by only SCSR or LHB, and SCSR + LHB, comparing each cardiac performances, infarcted areas and coronary flow. Infarcted areas were evaluated by epicardial mapping ECG. Coronary blood flow and velocity were analyzed by electromagnetic flow meter and ultrasonic pulse doppler velocimeter respectively. In LHB group, coronary blood flow and velocity were increased because of elevation of mean aortic pressure. In addition, LVdp/dt, LVEDP were decreased, indicating left ventricular decompression. However, the infarcted area was slightly reduced. In contrast, it was remarkably reduced by SCSR, and cardiac function recovered gradually from cardiogenic shock. In SCSR + LHB group, the ischemic area was significantly reduced and their hearts completely recovered from cardiogenic shock, demonstrating the good supply and demand balance of myocardial oxygen. The systolic reverse LAD flow and velocity which was increased due to cardiogenic shock, was remarkably reduced. These results suggested this concomitant new application is suitable for recovering from cardiogenic shock due to AMI which is not able to apply antegrade coronary perfusion.     

Integrated MRI assessment of regional function and perfusion in canine myocardial infarction

A single integrated examination using regional measurements of perfusion from contrast-enhanced MRI and three-dimensional (3D) strain from tissue-tagged MRI was developed to differentiate infarcted myocardium from adjacent tissue with functional abnormalities. Ten dogs were studied at baseline and 10 days after a 2-hour occlusion of the left anterior descending coronary artery (LAD). Strain was determined using a 3D finite element model. Two-dimensional measurements of hypoenhancing regions were highly correlated with myocardial viability (r = 0.96). Signal intensity versus time curves obtained from contrast-enhanced MRI were used for quantitative perfusion analysis. The remote and adjacent noninfarcted tissue of the dogs with LAD occlusion, as well as the infarcted tissue, exhibited abnormal deformation patterns as compared to normal dogs (positive predictive value (PPV) of strain determination of infarction = 66%). Integration of contrast-enhanced MRI results with 3D strain analysis enabled the delineation of the myocardial infarction (PPV = 100%) from functionally compromised myocardium. This integrated cardiac examination shows promise for noninvasive serial assessment of potentially jeopardized noninfarcted myocardium to study the process of infarct remodeling and expansion.     

Indications for palliative reduction surgery for hepatocellular carcinoma with multiple intrahepatic metastases

It is assumed that stenosis of the right coronary artery (RCA) predisposes CABG patients, by way of incomplete atrial myocardial protection, to postoperative atrial fibrillation (AF). Sixty patients with high-grade RCA lesion were randomized into four groups according to the technique of delivery of cold blood cardioplegia: antegrade, retrograde, retrograde without catheter cuff, and combined antegrade and retrograde. As controls, 34 patients without RCA lesion were randomized to receive antegrade or retrograde cardioplegia. Postoperative atrial fibrillation episodes were recorded. Patients with RCA lesion were more prone to develop AF; odds ratio (OR)=3.75 (95% confidence interval [CI]=1.22-11.5). Retrograde delivery in these patients was more often associated with AF, OR=4.97 (95% CI = 1.02-24.1). Other risk factors for AF were an increasing number of preoperative infarcts (p < 0.05) and more advanced coronary artery disease (p < 0.05). Prolonged stay in the intensive care unit (p < 0.001) and occurrence of postoperative ventricular tachycardia (p < 0.05) were associated with AF. RCA stenosis and retrograde cardioplegia delivery in RCA-affected patients were risk factors for postoperative atrial fibrillation. Retrograde cardioplegia may offer poorer protection at the atrial level.     

Inhibition of angiotensin-converting enzyme increases the nitric oxide levels in canine ischemic myocardium

Since angiotensin-converting enzyme (ACE) produces angiotensin II in the heart, ACE inhibitors may prevent coronary vasoconstriction and increase coronary blood flow. On the other hand, since ACE inhibitors also inhibit kininase II which results in reduced degradation of bradykinin, ACE inhibitors may increase cardiac nitric oxide (NO) levels via stimulation of bradykinin receptors. This study was undertaken to test whether ACE inhibitors increase the cardiac NO levels and coronary blood flow in the ischemic myocardium. In 34 open-chest dogs, the left anterior descending coronary artery was perfused through an extracorporeal bypass tube from the left carotid artery. When either imidaprilat or cilazaprilat of 3 microg/kg/min was infused into the bypass tube for 10 min after reduction of coronary blood flow due to partial occlusion of the bypass tube, coronary blood flow increased from 31 +/- 1 to either 45 +/- 5 or 43 +/- 4 ml/100 g/min despite no changes in coronary perfusion pressure (43 +/- 2 mmHg). During an infusion of either imidaprilat or cilazaprilat, bradykinin and the end-products of NO (nitrate + nitrite) concentrations of coronary venous blood were markedly increased, which were attenuated by either HOE-140 (an inhibitor of bradykinin receptors) or by N(omega)-nitro-L-arginine methyl ester (an inhibitor of NO synthase). We also observed increases in cardiac bradykinin and NO levels due to either imidaprilat or cilazaprilat in the low constant coronary blood flow condition. It is concluded that ACE inhibitors can increase cardiac NO levels via the accumulation of bradykinin in the ischemic myocardium.