Omer Dzemali

Venoarterial extracorporeal membrane oxygenation for treatment of cardiogenic shock: Clinical experiences in 45 adult patients

OBJECTIVE Venoarterial extracorporeal membrane oxygenation is an established treatment option in patients with cardiogenic shock. This report reviews our 3-year experience with this support system with respect to early and midterm outcome, as well as predictors of survival. METHODS From January 2003 until November 2006, 45 (0.8%) of 5750 patients undergoing cardiac surgery procedures required the following: temporary extracorporeal membrane oxygenation support coronary artery bypass grafting, n = 20; implantation of a left ventricular assist device, n = 5; heart transplantation, n = 1; heart and lung transplantation, n = 1; coronary artery bypass grafting plus repair of postinfarction ventricular septal defect, n = 3; coronary artery bypass grafting plus mitral valve repair, n = 5; aortic valve replacement, n = 2; coronary artery bypass grafting plus aortic valve replacement, n = 3; and other procedures, n = 5. Extracorporeal membrane oxygenation implantation was performed through the femoral vessels or axillary artery or through the right atrium and ascending aorta. Additional intra-aortic balloon pumps were used in 30 patients. RESULTS Average patient age was 60.1 +/- 13.6 years. There were 35 male patients. Average duration of extracorporeal membrane oxygenation was 6.4 +/- 4.5 days. Twenty-five patients could be successfully weaned from extracorporeal membrane oxygenation. The 30-day mortality was 53% (24/45 patients). The in-hospital mortality was 71% (32/45 patients). Thirteen (29%) patients could be successfully discharged. After a follow-up period of up to 3 years, 10 (22%) patients were still alive. CONCLUSIONS Extracorporeal membrane oxygenation offers sufficient cardiopulmonary support in adults with similar hospital and midterm survival rates to those of other mechanical support systems. Early indication, alternative peripheral cannulation techniques, and reduced anticoagulation to avoid perioperative bleeding could improve our results with increasing experience.

Antegrade Cerebral Perfusion With Mild Hypothermia for Aortic Arch Replacement: Single-Center Experience in 245 Consecutive Patients

BACKGROUND Aortic arch replacement remains a surgical challenge because of prolonged operative times, bleeding complications, and a considerable risk of neurologic morbidity and mortality. This study investigates our clinical results after modification of perfusion technique for cardiopulmonary bypass as well as temperature management for these high- risk patients. METHODS Between January 2000 and January 2009, 245 consecutive patients underwent aortic arch repair during selective antegrade cerebral perfusion (ACP) with mild systemic hypothermia (30.5°C±1.4°C). Mean age was 63±12 years, 175 patients (71%) were men and 141 patients (58%) had acute type A dissection. Hemiarch replacement was performed in 152 patients (62%) while the remaining 93 patients (38%) underwent total arch replacement. RESULTS Cardiopulmonary bypass time accounted for 168±62 minutes, and myocardial ischemic time was 103±45 minutes. Isolated ACP was performed for 38±27 (range 12 to 135) minutes. Chest tube drainage during the first 24 hours was 563±248 mL. Mean ventilation time was 44±22 hours. Serum lactate levels at 1, 12, and 24 hours postoperatively rose to 19±11, 33±14, and 20±8 mg/dL, respectively. We observed new postoperative permanent neurologic deficits in 14 patients (6%) and transient neurologic deficits in 12 patients (5%). The operative mortality rate was 8% (n=20). Among patients with ACP times 60 minutes or greater (n=28; 92±29 minutes), permanent neurologic deficits occurred in 2 individuals (n=2 of 28; 7%) and operative mortality was 7% (n=2 of 28). At late follow-up (3.8±3.2 years, 98% complete), 196 patients (80%) were still alive. CONCLUSIONS Selective ACP in combination with mild hypothermia offered sufficient cerebral as well as distal organ protection in our patient cohort. Thus, current data suggest that this standardized perfusion and temperature management protocol can safely be applied to complex aortic arch surgery requiring up to 90 minutes of isolated ACP times.

Antegrade Cerebral Perfusion for Acute Type A Aortic Dissection in 120 Consecutive Patients

BACKGROUND Treatment of acute type A aortic dissection remains a surgical challenge because of prolonged operative times, bleeding complications, and a considerable risk of neurologic morbidity and mortality. The following study investigates clinical results after modification of perfusion technique for cardiopulmonary bypass as well as temperature management. METHODS Between January 2000 and August 2006, 120 consecutive patients underwent repair of acute type A dissection. Selective antegrade cerebral perfusion through the right subclavian artery combined with mild systemic hypothermia (30 degrees C) was used in all patients. RESULTS Mean cardiopulmonary bypass time was 144 +/- 53 minutes, and mean myocardial ischemic time was 98 +/- 49 minutes. Isolated cerebral perfusion was performed for 25 +/- 12 minutes. Mean core temperature amounted to 30.1 degrees +/- 2.2 degrees C. Chest tube drainage during the first 24 hours was 525 +/- 220 mL. Mean ventilation time was 54 +/- 22 hours. Elevation of serum lactate levels at 1, 12, and 24 hours postoperatively rose to 22 +/- 14, 18 +/- 11, and 19 +/- 8 mg/dL respectively. We observed new postoperative permanent neurologic deficits in 5 patients (4.2%) and TND in 3 patients (2.5%). The 30-day mortality rate was 5% (n = 6). After a mean follow-up period of 2.8 years, 104 patients (87%) were still alive. CONCLUSIONS Antegrade cerebral perfusion in combination with mild hypothermia offered sufficient neurologic protection in our patient cohort, provided adequate distal organ protection, and reduced perioperative complications in surgery for type A dissection. This perfusion strategy may help in reducing perioperative complications in this particular patient population.

Leukocyte filtration fails to limit functional neutrophil activity during cardiac surgery

Abstract. Objective and design: The beneficial effects of leukocyte filtration on the outcome of cardiac surgery with cardiopulmonary bypass (CPB) is probably due to the limitation of pathogenesis mediated by over-stimulated neutrophils. However, the influence of leukocyte filtration on the functional neutrophil activity has not been studied in detail. Therefore, by using different filtration timing strategies we determined neutrophil effector functions before and after the filter passage as well as blood surrogate markers for neutrophil activation.¶Methods: We randomly assigned 80 cardiac surgery patients to four groups (n = 20 each) without (I) and with three different filtration timing strategies (II–IV). As functional end points neutrophil phagocytic activity and oxidative burst upon ex vivo stimulation with E.coli were analyzed from blood of 31 patients whereas polymorphonuclear elastase (PMNE), myeloperoxidase, and malondialdehyde (MDA), a marker for lipid peroxidation was determined in plasma samples from 80 patients. Blood was harvested immediately before and behind the filter (Pall LG6) at different times during CPB.¶Results: We found that none of the filtration strategies either reduced the number of neutrophils capable of eliciting phagocytic activity and oxidative burst or the activity per cell. In contrast, PMNE and MPO levels in peripheral venous blood were found to be significantly increased in groups II–IV compared with group I throughout the entire filtration period in all patients. MDA was not enhanced in the filter groups.¶Conclusions: Our results show that the leukocyte depletion filter in the arterial line of the heart-lung machine failed to limit neutrophil stimulation but rather augmented PMNE plasma levels. We speculate that augmented PMNE and MPO levels mainly stem from neutrophils that are captured within the mesh of the leukocyte filter.

Long-Term Results After Surgical Repair of Postinfarction Ventricular Septal Rupture by Infarct Exclusion Technique

BACKGROUND Ventricular septal defect (VSD) is one of the most serious and life-threatening complications of acute myocardial infarction. The aim of this study was to evaluate the early and long-term results of the patients after surgical repair of postinfarction VSD by infarct exclusion technique. METHODS A total of 32 consecutive patients (mean age, 62.5 +/- 10.5 years) underwent postinfarction VSD repair using a standardized technique in our department. A retrospective analysis of clinical and operative data, predictors of early mortality, and long-term survival was performed. The localization of VSD was posterior in 50% and anterior in 50% of the patients. RESULTS The hospital mortality was 31.2% (10 patients). The most common cause of hospital death was persistent low cardiac output. The mortality of the posterior VSD group was significantly lower than that of the anterior VSD group (18.7% and 43.7%, respectively, p = 0.01). Intra-aortic balloon pump support and absence of cardiac shock were significantly associated with a lower risk of hospital mortality (p = 0.0001 and p = 0.0009, respectively). The actuarial survival rates of in-hospital survivors at 5 and 10 years were 79% +/- 2% and 51% +/- 3%, respectively. CONCLUSIONS The repair of postinfarction VSD by the infarct exclusion is feasible and safe. This technique seems to offer sufficient favorable early and long-term results compared with other techniques. Early indication, preoperative intra-aortic balloon pump support may improve the surgical results. Preoperative cardiogenic shock carries a poor prognosis for this patient group.

Flow Distribution During Cardiopulmonary Bypass in Dependency on the Outflow Cannula Positioning

Oxygen deficiency in the right brain is a common problem during cardiopulmonary bypass (CPB). This is linked to an insufficient perfusion of the carotid and vertebral artery. The flow to these vessels is strongly influenced by the outflow cannula position, which is traditionally located in the ascending aorta. Another approach however is to return blood via the right subclavian artery. A computational fluid dynamics (CFD) study was performed for both methods and validated by particle image velocimetry (PIV). A 3-dimensional computer aided design model of the cardiovascular (CV) system was generated from realtime computed tomography and magnetic resonance imaging data. Mesh generation (CFD) and rapid prototyping (PIV) were used for the further model creation. The simulations were performed assuming usual CPB conditions, and the same boundary conditions were applied for the PIV validation. The flow distribution was analyzed for 55 cannula positions inside the aorta and in relation to the distance between the cannula tip and the vertebral artery branch for subclavian cannulation. The study reveals that the Venturi effect due to the cannula jet appears to be the main reason for the loss in cerebral perfusion seen clinically. It provides a PIV-validated CFD method of analyzing the flow distribution in the CV system and can be transferred to other applications.

The Impact of Aortic/Subclavian Outflow Cannulation for Cardiopulmonary Bypass and Cardiac Support: A Computational Fluid Dynamics Study

Approximately 100 000 cases of oxygen deficiency in the brain occur during cardiopulmonary bypass (CPB) procedures each year. In particular, perfusion of the carotid and vertebral arteries is affected. The position of the outflow cannula influences the blood flow to the cardiovascular system and thus end organ perfusion. Traditionally, the cannula returns blood into the ascending aorta. But some surgeons prefer cannulation to the right subclavian artery. A computational fluid dynamics study was initially undertaken for both approaches. The vessel model was created from real computed tomography/magnetic resonance imaging data of young healthy patients. The simulations were run with usual CPB conditions. The flow distribution for different cannula positions in the aorta was studied, as well as the impact of the cannula tip distance to vertebral artery for the subclavian position. The study presents a fast method of analyzing the flow distribution in the cardiovascular system, and can be adapted for other applications such as ventricular assist device support. It revealed that two effects cause the loss of perfusion seen clinically: a vortex under the brachiocephalic trunk and low pressure regions near the cannula jet. The results suggest that cannulation to the subclavian artery is preferred if the cannula tip is sufficiently far away from the branch of the vertebral artery. For the aortic positions, however, the cannula should be injected from the left body side.

Leukocyte filtration in cardiac surgery: a review

Leukocyte filtration has evolved as an important technique in cardiac surgery with cardiopulmonary bypass to prevent pathogenic effector functions mediated by activated leukocytes. The underlying mechanisms that result in an improvement of laboratory variables as well as clinical outcome are not resolved yet. Moreover, the optimum strategy for the use of current filtration technology has not been systematically evaluated. This paper, therefore, reviews how activated leukocytes may lead to tissue damage, summarizes the known effects of leukocyte filtration on clinical outcome and laboratory parameters, and deals with current experimental and clinical efforts to further limit the pathogenic effects of leukocytes in cardiac surgery.

Simplified technique for surgical ligation of the left atrial appendage in high-risk patients.

References 1. Serna DL, Miller JS, Chen EP. Aortic reconstruction after complex injury to mid-transverse arch. Ann Thorac Surg. 2006;81:1112-4. 2. Carter YM, Karmy-Jones R, Alder GS. Delayed surgical management of a traumatic aortic arch injury. Ann Thorac Surg. 2002;73:294-6. 3. Smayra T, Noun R, Tohme-Noun C. Left anterior descending artery dissection after blunt chest trauma: assessment by Multidetector row computed tomography. J Thorac Cardiovasc Surg. 2007;133:811-2. 4. Korach A, Hunter CT, Lazar HL, Shemin RJ, Shapira OM. OPCAB for acute LAD dissection due to blunt chest trauma. Ann Thorac Surg. 2006;82:312-4. Brief Communications

Totally endoscopic coronary artery bypass graft: initial experience with an additional instrument arm and an advanced camera system

Background:Robotically enhanced telemanipulation for totally endoscopic coronary artery bypass does not provide adequate tactile feedback, traction, or countertraction. The exposition of coronary target sites is difficult, the visual field is limited, and the epicardial stabilization may be troublesome. A fourth robotic arm for endothoracic instrumentation has been added to the da Vinci surgical system to facilitate totally endoscopic operations. The stereoendoscope was upgraded with a wide-angle feature.Methods:The procedure was performed in five patients. Four of these patients had left internal thoracic artery (LITA) to left anterior descending artery (LAD) grafting on the beating heart and the fifth had sequential bypass grafting (LITA to diagonal branch and LAD) on an arrested heart. The additional effector arm of the da Vinci surgical system was brought into the operative field beneath the operating table and used as a second right arm. The wide-angle view was activated by either the console or the patient side surgeon.Results:The mean operative, port placement, and anastomotic times for a beating-heart totally endoscopic coronary artery bypass were 195 ± 58, 25 ± 10, and 18 ± 5 min, respectively. All procedures were free of morbidity and mortality, with satisfactory angiographic control. The sequential arterial bypass grafting procedure was fully completed in totally endoscopic technique.Conclusions:The additional instrumentation arm and wide-angle visualization are useful technical improvements of the da Vinci surgical system, solving the problem of traction, countertraction, and facilitated exposition of target sites as well as visualization of the surgical field. They provide potential for wider acceptance of totally endoscopic coronary artery bypass grafting in a larger surgical community.