Ivan Aleksic

Orthotopic heart transplantation with bicaval and pulmonary venous anastomoses.

We present our experience with an alternative technique for orthotopic heart transplantation. It consists of total excision of the recipients atria, with the donors heart implantation performed using bicaval end-to-end anastomoses as well as pulmonary venous anastomoses. Forty consecutive patients receiving transplants in this fashion were compared with 64 patients who underwent orthotopic transplantation with the standard technique. The incidence of postoperative tricuspid regurgitation was reduced in patients receiving transplants with the new surgical approach (p = 0.003). In addition, the need for pacemaker implantation for severe bradyarrhythmia in the early (0 to 6 weeks) posttransplantation period (p = 0.003) was eliminated. Although not statistically significant, there was a trend in the reduction of postoperative mitral regurgitation in patients who received transplants by the modified technique. Based on this experience, we believe this modified technique for orthotopic heart transplantation has an anatomic and physiologic advantage that may improve long-term hemodynamic results.

Atrial emptying with orthotopic heart transplantation using bicaval and pulmonary venous anastomoses: A magnetic resonance imaging study

OBJECTIVES We hypothesized that orthotopic heart transplantation with bicaval and pulmonary venous anastomoses preserves atrial contractility. BACKGROUND The standard biatrial anastomotic technique of orthotopic heart transplantation causes impaired function and enlargement of the atria. Cine magnetic resonance imaging (MRI) allows assessment of atrial size and function. METHODS We studied 16 patients who had undergone bicaval (n = 8) or biatrial (n = 8) orthotopic heart transplantation without evidence of rejection and a control group of 6 healthy volunteers. For all three groups, cine MRI was performed by combining coronal and axial gated spin echo and gradient echo cine sequences. Intracardiac volumes were calculated with the Simpson rule. Atrial emptying fraction was defined as the difference between atrial diastolic and systolic volumes, divided by atrial diastolic volume, expressed in percent. All patients had right heart catheterization. RESULTS Right atrial emptying fraction was significantly higher in the bicaval (mean [+/- SD] 37 +/- 9%) than in the biatrial group (22 +/- 11%, p < 0.05) and similar to that in the control group (48 +/- 4%). Left atrial emptying fraction was significantly higher in the bicaval (30 +/- 5%) than in the biatrial group (15 +/- 4%, p < 0.05) and significantly lower in both transplant groups than in the control group (47 +/- 5%, p < 0.05). The left atrium was larger in the biatrial than in the control group (p < 0.05). Cardiac index, stroke index, heart rate and blood pressure were similar in the transplant groups. CONCLUSIONS Left and right atrial emptying fractions are significantly depressed with the biatrial technique and markedly improved with the bicaval technique of orthotopic heart transplantation. The beneficial effects of the latter technique on atrial function could improve allograft exercise performance.

Ischemia-reperfusion injury–induced pulmonary mitochondrial damage

BACKGROUND Mitochondrial dysfunction is a key factor in solid organ ischemia-reperfusion (IR) injury. Impaired mitochondrial integrity predisposes to cellular energy depletion, free radical generation, and cell death. This study analyzed mitochondrial damage induced by warm pulmonary IR. METHODS Anesthetized Wistar rats received mechanical ventilation. Pulmonary clamping was followed by reperfusion to generate IR injury. Rats were subjected to control, sham, and to 2 study group conditions: 30 minutes of ischemia without reperfusion (IR30/0), or ischemia followed by 60 minutes of reperfusion (IR30/60). Pulmonary edema was quantified by wet/dry-weight ratio. Polarography determined activities of respiratory chain complexes. Mitochondrial viability was detected by using Ca(2+)-induced swelling, and integrity by citrate synthase assay. Enzyme-linked immunosorbent assay determined cytochrome C content. Mitochondrial membrane potential (ΔΨm) stability was analyzed by flow cytometry using JC1, inflammation by myeloperoxidase (MPO) activity, and matrix-metalloproteinase-9 (MMP-9) activity by gel zymography, respectively. RESULTS In IR30/60 rats, tissue water content was elevated from 80.6 % (sham) to 86.9%. After ischemia, ΔΨm showed hyperpolarization and rapid decline after uncoupling compared with controls. IR, but not ischemia alone, impaired respiratory chain function complexes I, II and III (p < 0.05). Mitochondrial viability (p < 0.001) and integrity (p < 0.01) was impaired after ischemia and IR, followed by mitochondrial cytochrome C loss (p < 0.05). Increased activation of MPO (p < 0.01) and MMP-9 (p < 0.001) was induced by reperfusion after ischemia. CONCLUSIONS Ischemia-related ΔΨm hyper-polarization induces reperfusion-associated mitochondrial respiratory chain dysfunction in parallel with tissue inflammation and degradation. Controlling ΔΨm during ischemia might reduce IR injury.

The innominate vein as alternative venous access for complicated implantable cardioverter defibrillator revisions.

Background: Venous complications of implantable cardioverter defibrillator (ICD) systems may cause significant problems when the need for system revision or upgrades arises. Such revisions require venous access close to the site of the previous ICD implantation. The internal and external jugular vein have disadvantages due to a long subcutaneous course crossing the clavicle and problems with lead extraction if infection occurs.

Superior vena cava stenosis after orthotopic heart transplantation: complication of an alternative surgical technique

Superior vena cava stenosis presented as a postoperative complication of orthotopic heart transplantation in a patient in whom a new surgical technique was used. This alternative technique consists of total excision of the recipients atria, with donor heart implantation performed using bicaval and pulmonary venous anastomoses. This rare complication required surgical repair 1 month after transplantation. The patient remains well on long-term follow-up. The pathogenesis, surgical management and modifications of the alternative technique to prevent this potentially serious complication are discussed.

An Update on Transplantation in the Geriatric Heart Transplant Patient

Discussions of the ethics involved in allocating scarce resources often proceed without a grounding in factual experience. This study explored whether there was statistical evidence to support the use of set age limits in patient selection criteria for heart transplantation. Many transplant teams have selection criteria that include age limits, excluding patients more than 60 or 65 years of age from being considered as transplant candidates. The hypothesis was made that patients in the age bracket of 60-69 should have a comparable success rate with transplantation to that of younger recipients when selected by using the same medical and psychiatric criteria. Based on their clinical observations, the authors postulated that the elderly would report better quality of life postoperatively than younger control subjects.

Glutathione preconditioning ameliorates mitochondria dysfunction during warm pulmonary ischemia-reperfusion injury

OBJECTIVES Reduced glutathione (GSH) has been shown to improve pulmonary graft preservation. Mitochondrial dysfunction is regarded to be the motor of ischemia-reperfusion injury (IR) in solid organs. We have shown previously that IR induces pulmonary mitochondrial damage. This study elucidates the impact of GSH preconditioning on the integrity and function of pulmonary mitochondria in the setting of warm pulmonary IR. METHODS Wistar rats were subjected to control, sham, and to two-study-group conditions (IR30/60 and GSH-IR30/60) receiving IR with or without GSH preconditioning. Rats were anesthetized and received mechanical ventilation. Pulmonary in situ clamping followed by reperfusion generated IR. Mitochondria were isolated from pulmonary tissue. Respiratory chain complexes activities (I-IV) were analyzed by polarography. Mitochondrial viability (Ca2+-induced swelling) and membrane integrity (citrate synthase assay) were determined. Subcellular-fractional cytochrome C-content (Cyt C) was quantified by enzyme-linked immunosorbent assay (ELISA). Mitochondrial membrane potential (ΔΨm) was analyzed by fluorescence-activated cell sorting (FACS) after energizing and uncoupling. Inflammatory activation was determined by myeloperoxidase activity (MPO), matrix-metalloproteinase 9 (MMP-9) activity by gel zymography. RESULTS Pulmonary IR significantly reduced mitochondrial viability in combination with ΔΨm hyper-polarization. GSH preconditioning improved mitochondrial viability and normalized ΔΨm. Cyt C was reduced after IR; GSH protected from Cyt C liberation. Respiratory chain complex activities (I, II, III) declined during IR; GSH protected complex II function. GSH also protected from MMP-9 and neutrophil sequestration (P>.05). CONCLUSIONS GSH preconditioning is effective to prevent mitochondrial death and improves complex II function during IR, but not mitochondrial membrane stability. GSH-mediated amelioration of ΔΨm hyper-polarization appears to be the key factor of mitochondrial protection.

Critical closing pressure as the arterial downstream pressure with the heart beating and during circulatory arrest.

Background:Calculation of systemic vascular resistance, used for hemodynamic decision-making, is based on central venous pressure taken as the downstream pressure. However, during circulatory arrest, arterial pressure decreases to a plateau higher than central venous pressure, the critical closing pressure (Pcrit). The authors assessed in humans undergoing arrest whether two-compartment and pressure-dependent conductivity models better estimate arterial pressure decay and Pcrit than a single-compartment model, and whether Pcrit corresponds to Pcrit calculated with the heart beating. Methods:Aortic pressure decay was fitted to single-compartment, two-compartment, and pressure-dependent conductivity models using specified time intervals during arrest and natural diastole in 10 patients during defibrillator implantation. Results:Although all models closely predicted Pcrit with an arrest of ≥ 7s, both two-compartment and pressure-dependent conductivity models better estimated pressure decay than a single-compartment model. However, Pcrit calculated from natural diastolic pressure decay was greater (53 mmHg ± 15.6) than Pcrit 15 s (26.6 mmHg ± 7.8, P = 0.001) and 30 s (23.9 mmHg ± 7.1, P = 0.001) during arrest, and also greater than Pcrit calculated for the same time interval during initial arrest. Conclusions:Thus, during arrest, Pcrit can be closely predicted after ≥ 7 s, regardless of the model; two-compartment and pressure-dependent conductivity models provide a better fit than a single-compartment model, and actual Pcrit is much less than Pcrit calculated with the heart beating. Irrespective of uncertainties in whether Pcrit calculated with the heart beating or during arrest is the “true” Pcrit prevailing physiologically, linear vascular resistance is markedly less when substituting Pcrit for central venous pressure as the downstream pressure.

Cardiac surgery and hematologic malignancies: a retrospective single-center analysis of 56 consecutive patients

OBJECTIVE Patients with a history of hematologic malignancies (HMs) are considered high-risk candidates for cardiac surgery. Increased perioperative rates of infections, thrombo-embolic complications, and bleeding disorders are reported. However, low patient numbers and lack of control groups limit all published studies. METHODS A total of 56 patients with a history of HM underwent cardiac surgery. As many as 29 patients suffered from non-Hodgkin lymphoma, five from Hodgkin disease, and 12 from myeloproliferative disorders, one from acute lymphatic leukemia, and nine from monoclonal gammopathy. Surgery consisted of coronary artery bypass grafting, valvular surgery or combination procedures. HM patients were matched to 142 controls. Matching criteria applied consisted of sex, age, main diagnosis, and co-morbidities. RESULTS In-hospital mortality was elevated in HM patients though not reaching significance (P = 0.7). HM patients demonstrated increased rates of vascular, pulmonary, infectious complications (P > 0.1), and transfusion requirements (P = 0.077). The long-term survival of HM patients was significantly impaired (P = 0.043). A history of irradiation or chemotherapy predisposed to postoperative respiratory insufficiency, acute renal failure, and an impaired long-term survival (P > 0.065). CONCLUSIONS Cardiac surgery in patients with a history of a malignant hematologic disorder might achieve acceptable results. However, a higher complication and mortality rate have to be anticipated. Patients with hematologic disorders and a history of either irradiation or chemotherapy appear to be at an increased risk to develop postoperative end-organ failure.

Cardiac Operations in the Presence of Meningioma

BACKGROUND We investigated the effect of concomitant intracranial meningiomas on perioperative and postoperative complications after cardiac operations. Also studied was the intraoperative and perioperative management and long-term outcome of such patients. METHODS We retrospectively evaluated 16 cardiac surgical patients with intracranial meningiomas between January 1996 and July 2007. Neurologic outcome, incidence of transient neurologic deficits, and long-term follow-up focusing on freedom from any cardiac or neurosurgical intervention were assessed. RESULTS Five men and 11 women with a concomitant diagnosis of intracranial meningioma underwent cardiac operations using extracorporeal circulation. One patient received additional edema prophylaxis by intravenous dexamethasone. All patients were discharged home in good physical condition. Data on long-term survival were available on 14 patients, with 12 alive. Postoperatively, 2 patients died from myocardial infarction at 26.8 months and 2 from metastatic colon cancer at 57.9 months. Perioperative neurologic disorders were observed in 2 patients, comprising one stroke after intervention for aortic dissection and one thromboembolic event 2 weeks after biologic mitral valve replacement due to anticoagulation disorders. No meningioma-related adverse event was observed. CONCLUSIONS The presence of intracranial meningioma does not appear to be a risk factor for patients undergoing cardiac operations. No meningioma-related neurologic sequelae were documented postoperatively. Neurosurgical consultation should be obtained in all patients preoperatively.