HOE-642 (cariporide) alters pH(i) and diastolic function after ischemia during reperfusion in pig hearts in situ.

The specific Na(+)/H(+) exchange inhibitor HOE-642 prevents ischemic and reperfusion injury in the myocardium. Although this inhibitor alters H(+) ion flux during reperfusion in vitro, this action has not been confirmed during complex conditions in situ. Myocardial intracellular pH (pH(i)) and high-energy phosphates were monitored using (31)P magnetic resonance spectroscopy in open-chest pigs supported by cardiopulmonary bypass during 10 min of ischemia and reperfusion. Intravenous HOE-642 (2 mg/kg; n = 8) administered before ischemia prevented the increases in diastolic stiffness noted in control pigs (n = 8), although it did not alter the postischemic peak-elastance or pressure-rate product measured using a distensible balloon within the left ventricle. HOE-642 induced no change in pH(i) during ischemia but caused significant delays in intracellular realkalinization during reperfusion. HOE-642 did not alter phosphocreatine depletion and repletion but did improve ATP preservation. Na(+)/H(+) exchange inhibition through HOE-642 delays intracellular alkalinization in the myocardium in situ during reperfusion in association with improved diastolic function and high-energy phosphate preservation.

[Is coronary artery bypass grafting under extracorporeal circulation the only technic that assures complete myocardial revascularization? Pros and cons]. / Es el injerto aortocoronario bajo circulación extracorpórea la única técnica que asegura la revascularización miocárdica completa? Pros y contras.

Like other technical advances in medicine, the initial phase of rejection of off-pump revascularization has given way to its acceptance with some limitations. Today's main concern is whether the technique can be safely applied to access all coronary arteries, specially the postero-lateral vessels of the heart. We believe that off-pump CABG has proven to be an excellent alternative to the standard revascularization techniques avoiding the risks and complications of cardiopulmonary bypass (CPB). It can be applied to any case with minimal incidence of conversions thus avoiding the complications of CPB. In this debate we describe our technique, discuss our experience with complete myocardial revascularization, and suggest that the CPB machine should be a readily available tool for more complex cases rather than the current concept that it is an indispensable element for myocardial revascularization.

Perspectives of a cardiac surgery resident in-training on off-pump coronary bypass operation.

BACKGROUND: Contemporary residency training in the cardiac component of cardiothoracic operation is focused mainly on attaining technical proficiency in coronary artery revascularization. Most trainees in cardiothoracic operation are required to perform 35 cases of coronary revascularization in order to fulfill the minimum requirements for certification by the American Board of Thoracic Surgery. Although experience in minimally invasive coronary revascularization is not required for board certification in cardiothoracic operation, it is recognized by both trainees and program directors as an important component of contemporary training in less-invasive surgical approaches (LISA) for coronary artery disease. The objective of this study was to describe the training of residents in off-pump coronary revascularization in an accredited training program. METHODS: A retrospective analysis of a single resident's experience in minimally invasive coronary revascularization over an 18 month period in a 2-year residency program in cardiothoracic operation was carried out. RESULTS: Of the 166 total cases of coronary bypass operation, the resident performed 61 cases (37% of the total) off-pump as primary surgeon with attending supervision. Patients undergoing off-pump coronary bypass had an average of 2.4 grafts (range 1 to 5) and conventional coronary artery surgeon (on cardiopulmonary bypass) performed by the resident had an average of 4 grafts (range 2 to 5). The marginal/circumflex system was bypassed in patients that required revascularization of the marginal/circumflex system, which was 56% (n = 36 of 62) in the off-pump group and 90% for the conventional group using cardiopulmonary bypass. The conversion rate from off-pump technique to conventional coronary bypass using cardiopulmonary bypass was 3.2% in this series. CONCLUSIONS: Technical innovations and evolution of techniques to better stabilize the heart for off-pump coronary revascularization have made the procedure both effective and safe. Our experience has shown that cardiothoracic residents can be taught the skills necessary to perform coronary revascularization off cardiopulmonary bypass. There are currently no standards for the training of cardiothoracic residents in off-pump coronary artery operation. We propose that at least 50 cases be performed under supervision by a trained surgeon to obtain adequate credentials in minimally invasive coronary revascularization.

Blood product use in cardiac revascularization: comparison of on- and off-pump techniques.

BACKGROUND: Cardiac revascularization on a beating heart avoids the side effects of cardiopulmonary bypass (eg, neurologic injury, hemodilution, and coagulopathy). We examined perioperative bleeding and use of blood products during coronary artery bypass grafting using either on-pump or off-pump techniques. METHOD: The charts of 126 patients who had coronary artery bypass grafting were reviewed. Data from 66 patients revascularized off pump and 60 patients with cardiopulmonary bypass (on pump) were analyzed using unpaired Student's t test. RESULTS: Average age was 62.5 years in either group. More patients received heparin preoperatively in the off-pump group that resulted in mild elevation of preoperative partial thromboplastin time and activated clotting time (40.4 +/- 2.9 seconds and 150.1 +/- 5.3 seconds, respectively). However, the off-pump group had less perioperative (intraoperative or postoperative) bleeding (2312 +/- 212 mL versus 3251 +/- 155 mL, p < 0.05) and required fewer blood products compared with the on-pump group. Hemoglobin and platelets decreased more in the conventional on-pump group. CONCLUSIONS: Avoiding cardiopulmonary bypass decreases perioperative bleeding and, consequently, reduces the use of blood products after coronary artery bypass grafting, which might result in fewer transfusion-related complications.

Techniques of exposure and stabilization in off-pump coronary artery bypass graft.

Recent advances in techniques of coronary artery exposure and myocardial stabilization in off-pump myocardial revascularization have provided cardiac surgeons with a wide variety of new devices and techniques. Until recently, the main obstacle to performing complete myocardial revascularization without using cardiopulmonary bypass (CPB) has been the technical difficulties of exposing and stabilizing coronary targets, especially those located on the lateral and inferior wall of the heart. The extraordinary cardiac tolerance to nonconstrictive anterior elevation and lateral displacement, however, has allowed the development of new strategies of coronary exposure. These advances, in combination with the development of new techniques of mechanical myocardial stabilization, have impacted on the feasibility and safety with which coronary anastomoses on the beating heart can be constructed. The aim of this article is to describe the technical aspects involved in off-pump coronary revascularization, focusing primarily on the most recent strategies of cardiac elevation and coronary exposure, the various techniques of myocardial stabilization, and some of the technical details of constructing distal anastomoses on the beating heart.

Influence of the pH of cardioplegic solutions on cellular energy metabolism and hydrogen ion flux during neonatal hypothermic circulatory arrest and reperfusion: a dynamic 31P nuclear magnetic resonance study in a pig model.

OBJECTIVES: The pH of cardioplegic solutions is postulated to affect myocardial protection during neonatal hypothermic circulatory arrest. Neither optimization of cardioplegic pH nor its influence on intracellular pH during hypothermic circulatory arrest has been previously studied in vivo. Thus we examined the effects of the pH of cardioplegic solutions on postischemic cardiac function in vivo, including two possible operative mechanisms: (1) reduction in adenosine triphosphate use and depletion of high-energy phosphate stores or (2) reduction of H+ flux during reperfusion, or both. METHODS: Dynamic 31P spectroscopy was used to measure rates of adenosine triphosphate use, high-energy phosphate depletion, cytosolic acidification during hypothermic circulatory arrest, and phosphocreatine repletion and realkalinization during reperfusion. Neonatal pigs in three groups (n = 8 each)--group A, acidic cardioplegia (pH = 6.8); group B, basic cardioplegia (pH = 7.8); and group N, no cardioplegia--underwent hypothermia at 20 degrees C with 60 minutes of hypothermic cardioplegia followed by reperfusion. RESULTS: Recoveries of peak elastance, stroke work, and diastolic stiffness were superior in group B. Indices of ischemic adenosine triphosphate use, initial phosphocreatine depletion rate, and tau, the exponential decay half-time, were not different among groups. Peak [H+] in group A (end-ischemia) was significantly elevated over that of group B. The realkalinization rate was reduced in group B compared with that in groups A (p = 0.015) and N (p = 0.035), with no difference between groups A and N (p = 0.3). Cytosolic realkalinization rate was markedly reduced and the half-time of [H+] decay was increased during reperfusion in group B. CONCLUSIONS: Superior postischemic cardiac function in group B is not related to alterations in ischemic adenosine triphosphate use or high-energy store depletion, but may be due to slowing in H+ efflux during reperfusion, which should reduce Ca++ and Na+ influx.

The safety of simultaneous arterial and coronary sinus perfusion: experimental background and initial clinical results.

UNLABELLED: 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 mL/min with normal blood (37 degrees C) before and after 30 minutes of perfusion with either warm (37 degrees C) or cold (4 degrees 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 arterial/coronary 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 replacement/repair 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 implantation/repair in 123 patients, and warm continuous blood cardioplegia was used in 32 patients. Following a warm cardioplegic reperfusate, all patients received warm noncardioplegic 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.

Perspectives on myocardial protection: warm heart surgery.

Continuous normothermic blood cardioplegia (CNBC), was recently introduced into clinical cardiac surgery and has generated great interest. CNBC represents the evolution of concepts which were initially described in the 1950s but which were forgotten as hypothermia became the main ingredient in all cardioplegic techniques and in heart surgery in general. The historical background to the development of CNBC is presented, as well as a review of the current state of knowledge about normothermic heart surgery. The limitations and pitfalls of the method are highlighted, along with future developments and perspectives.

Coronary artery surgery without cardiopulmonary bypass: usefulness of the surgical blower-humidifier.

Coronary artery bypass surgery can be performed without cardiopulmonary bypass (CPB). Bleeding obscuring the operative field and hemodilution of shed blood with irrigating saline are some of the drawbacks of this technique. We report the use of a newly developed surgical blower-humidifier (custom made [Research Medical, Inc.]) for improved visualization and facilitation of coronary artery surgery without CPB.

Coronary sinus injuries during retrograde continuous normothermic blood cardioplegia.

Injuries to the coronary sinus during cardioplegic arrest are rare but potentially lethal. We herein present case reports of injuries to the coronary sinus occurring during retrograde continuous normothermic blood cardioplegia, and emphasize preventive measures and treatment.

Renal perfusion with the Biomedicus pump during resection of an abdominal aortic aneurysm.

Renal artery perfusion is usually unnecessary during resection of an abdominal aortic aneurysm, because most of these aneurysms are situated below the renal arteries. The authors report the interesting case of a patient with a solitary functioning kidney, who had undergone previous bypass grafting from the right iliac artery to the right renal artery and in whom the kidney was perfused with the Biomedicus pump during the repair of an abdominal aortic aneurysm. This technique may be useful in special situations in which any period of renal ischemia might be hazardous to renal function.

Replacement of the valvular prosthesis in a patient with a Bentall procedure.

Patients who have had the Bentall-DeBono procedure using a composite conduit with a tissue valvular prosthesis pose a great challenge when problems develop with the tissue prosthesis. We herein report the surgical management of one such case, in which the valvular prosthesis was removed and replaced without replacement of the conduit.

Optimal visualization of coronary artery anastomoses by gas jet.

A technique is described for improved visualization during the creation of coronary artery anastomoses employing a catheter-directed constant stream of oxygen to remove blood from the operative field. This technique is especially helpful when continuous blood cardioplegia is employed for myocardial protection.