Outcomes of Left Heart Bypass Versus Circulatory Arrest in Elective Open Surgical Descending and Thoraco-abdominal Aortic Repair.

OBJECTIVES: To compare early (30 day mortality and major complications) and midterm (survival) outcomes in elective open surgical descending and thoraco-abdominal aortic repair using left heart bypass (LHB) versus hypothermic circulatory arrest (HCA) for organ protection, hypothesising non-inferiority of HCA management. METHOD: This was a retrospective clinical cohort study with cross sectional follow-up. All elective (n = 90) descending or thoraco-abdominal aortic repairs performed between 2004 and 2015 using either LHB (n = 57) or HCA (n = 33) were included. Pre- and intra-operative variables were evaluated by univariate statistical analysis. Thirty day and follow-up mortality were primary endpoints; major complications were secondary endpoints. Propensity score matching was employed to adjust for selection bias. Kaplan-Meier methods were used to estimate midterm survival. RESULTS: Overall 30 day mortality was 8/90 (8.9%): 6/57 (10.5%) using LHB vs. 2/33 (6.1%) using HCA, p = .47. Five patients (5.6%) suffered paraplegia: 3/57 (5.3%) using LHB vs. 2/33 (6.1%) using HCA, p = .87. Stroke occurred in 6/57 (11%) vs. 2/33 (6.1%), p = .76; renal failure in 27/57 (47%) vs. 19/33 (58%), p = .90; and respiratory failure in 17/57 (30%) vs. 11/33 (33%), p = .68. In 26 propensity score matched pairs, findings remained unaltered. Total follow-up was 443 patient years (median 4.9 years). Estimated survival was 78% at 1 year and 77% at 5 years in LHB vs. 72% and 67%, respectively, with HCA; there were no significant inter-group differences, before or after propensity score matching. CONCLUSIONS: In elective descending or thoraco-abdominal aortic repair, no statistically significant differences in 30 day mortality, major complications, or follow-up survival were found when LHB and HCA were compared. These findings remained after propensity score matching.

Surgical repair of coarctation of aorta in adults under left heart bypass.

OBJECTIVE: To describe our experience with repair of coarctation of the aorta in adults using left heart bypass. METHODS: From November 2007 to October 2009, eight adult patients with coarctation of the aorta underwent surgical repair under circulatory support using a left atrium to femoral artery bypass circuit, with graft interposition tube through left posterolateral thoracotomy. Five patients were female, with mean age of 31.5 ± 13.1 years. All patients had hypertension and others associated cardiovascular diseases. RESULTS: There were no deaths or neurological complications. The mean surgical time was 308 minutes with mean left heart bypass and distal aortic clamping time of 73 and 65 minutes respectively. Postoperative bleeding was 696 ml in average. Six patients developed severe hypertension postoperatively requiring intravenous vasodilators. The mean length of stay was 9 days. A significant reduction of gradient blood pressure occurred. Echocardiographic follow-up up to two months postoperatively showed mean aortic / graft gradient of 20.3 mmHg. CONCLUSION: In this series the use of left heart bypass showed to be a safe option in the surgical correction of coarctation of the aorta in adults, especially in patients with abnormal aortic wall. There was no spinal cord ischemia in the cases studied.

Correção cirúrgica da coarctação da aorta em adultos sob assistência circulatória extracorpórea esquerda / Surgical repair of coarctation of aorta in adults under left heart bypass

OBJETIVO: Descrever a experiência do serviço com a correção da coarctação da aorta em adultos utilizando assistência circulatória esquerda. MÉTODOS: De novembro de 2007 a outubro de 2009, oito pacientes adultos com coarctação da aorta foram submetidos a correção cirúrgica com interposição de enxerto tubular através de toracotomia póstero-lateral esquerda e uso de assistência circulatória com uso de circuito átrio esquerdo e artéria femoral. Cinco pacientes eram do sexo feminino e tinham idade média de 31,5 ± 13,1 anos. Todos tinham hipertensão arterial sistêmica (HAS) e apresentavam doenças cardiovasculares associadas. RESULTADOS: Não houve óbitos ou complicações neurológicas. O tempo médio cirúrgico foi de 308 minutos, o tempo médio de assistência circulatória de 73 minutos e o de pinçamento aórtico médio de 65 minutos. O sangramento médio no pós-operatório foi de 696 ml. Seis pacientes evoluíram com HAS grave no pós-operatório, sendo necessário uso de vasodilatadores endovenosos. As altas hospitalares ocorreram em média no 9º dia pós-operatório. Houve redução significativa do gradiente médio da pressão arterial sistêmica. O seguimento ambulatorial com ecocardiograma até dois meses de pós-operatório demonstrou gradiente aorta/enxerto médio de 20,3 mmHg. CONCLUSÃO: O uso da assistência circulatória esquerda pode ser uma opção na correção cirúrgica da coarctação da aorta em adultos, principalmente em pacientes com alterações parede da aorta, não sendo observada isquemia medular nos casos estudados.

OBJECTIVE: To describe our experience with repair of coarctation of the aorta in adults using left heart bypass. METHODS: From November 2007 to October 2009, eight adult patients with coarctation of the aorta underwent surgical repair under circulatory support using a left atrium to femoral artery bypass circuit, with graft interposition tube through left posterolateral thoracotomy. Five patients were female, with mean age of 31.5 ± 13.1 years. All patients had hypertension and others associated cardiovascular diseases. RESULTS: There were no deaths or neurological complications. The mean surgical time was 308 minutes with mean left heart bypass and distal aortic clamping time of 73 and 65 minutes respectively. Postoperative bleeding was 696 ml in average. Six patients developed severe hypertension postoperatively requiring intravenous vasodilators. The mean length of stay was 9 days. A significant reduction of gradient blood pressure occurred. Echocardiographic follow-up up to two months postoperatively showed mean aortic / graft gradient of 20.3 mmHg. CONCLUSION: In this series the use of left heart bypass showed to be a safe option in the surgical correction of coarctation of the aorta in adults, especially in patients with abnormal aortic wall. There was no spinal cord ischemia in the cases studied.

Selective use of left heart bypass for aortic coarctation.

BACKGROUND: We evaluated left heart bypass (LHB) for spinal cord protection during aortic coarctation repair in patients with mild (primary, postsurgical, or intervention) and complex coarctation. METHODS: Between 1990 and 2008, 19 patients (mean age, 21 years; weight, 70 +/- 16 kg) using LHB were compared with 27 patients (mean age, 16 years; weight, 65 +/- 8 kg) undergoing coarctation repair without LHB (non-LHB). Follow-up was similar (LHB, 5 +/- 4 vs non-LHB 4 +/- 3 years; p = 0.81). RESULTS: Cohorts were similar in age and body surface area. No non-LHB patient lost somatosensory evoked potential or had a femoral artery pressure below 45 mm Hg with test clamping. LHB more often allowed graft interposition (18 of 19 [95%] vs non-LHB, 7 of 27 [26%]; p < 0.003) and a longer clamp time (LHB 44 +/- 16 vs non-LHB 31 +/- 12 minutes p < 0.003) without spinal cord ischemia. Two non-LHB patients had temporary spinal cord paresis. No early or late deaths occurred. Reintervention (LHB, 2 of 19 [11%] vs non-LHB, 2 of 27 [7%]; p = 0.82) and antihypertensive requirements were similar (LHB, 9 of 19 [40%] vs non-LHB, 8 of 27 [30%]; p = 0.35). The late peak transcoarctation gradient was 8 +/- 6 mm Hg in the LBH cohort vs 18 +/- 11 mm Hg in non-LBH patients (p= 0.001). CONCLUSIONS: Although the adequacy of spinal cord collateral assessment in coarctation repair is imperfect, no spinal cord ischemia occurred with coarctation repair and LHB. We recommend LHB in patients with mild or complex coarctation.

Development of a disposable maglev centrifugal blood pump intended for one-month support in bridge-to-bridge applications: in vitro and initial in vivo evaluation.

MedTech Dispo, a disposable maglev centrifugal blood pump with two degrees of freedom magnetic suspension and radial magnetic coupling rotation, has been developed for 1-month extracorporeal circulatory support. As the first stage of a two-stage in vivo evaluation, 2-week evaluation of a prototype MedTech Dispo was conducted. In in vitro study, the pump could produce 5 L/min against 800 mm Hg and the normalized index of hemolysis was 0.0054 +/- 0.0008 g/100 L. In in vivo study, the pump, with its blood-contacting surface coated with biocompatible 2-methacryloyloxyethyl phosphorylcholine polymer, was implanted in seven calves in left heart bypass. Pump performance was stable with a mean flow of 4.49 +/- 0.38 L/min at a mean speed of 2072.1 +/- 64.5 rpm. The maglev control revealed its stability in rotor position during normal activity by the calves. During 2 weeks of operation in two calves which survived the intended study period, no thrombus formation was seen inside the pump and levels of plasma free hemoglobin were maintained below 4 mg/dL. Although further experiments are required, the pump demonstrated the potential for sufficient and reliable performance and biocompatibility in meeting the requirements for cardiopulmonary bypass and 1-week circulatory support.

Helical computer assisted tomography in pulmonary hypertension complicating left-to-right shunts--correlation with pulmonary hemodynamics.

The present study analyzed the helical computer-assisted tomography (CAT) findings in 30 patients with pulmonary hypertension (PH) associated with left-to-right shunts; specifically, ventricular septal defect, 23; atrioventricular septal defect, 6; patent ductus arteriosus, 1. Eight patients had 21 trisomy. Age ranged from 1 to 18 (mean, 4.1) months, and body weight ranged from 2.6 to 10.7 (mean, 4.9) kg. In all patients, the chest CAT revealed patchy areas of high and low attenuation (mosaic pattern) and regional atelectasis in the lung fields. The volume of low attenuated lesions and of atelectasis, and the total lung volume were derived from integration of areas measured on the CAT image. The ratios of low attenuated lesion/total lung volume (Lo), volume of atelectasis/ total lung volume (Ate) and low attenuated lesion and volume of atelectasis/total lung volume (Lo&Ate) were compared with hemodynamic parameters measured at cardiac catheterization. The pulmonary to systemic resistance ratio correlated with Lo (r=0.61, p<0.01) and Lo&Ate (r=0.69, p<0.01), whereas the pulmonary vascular resistance correlated with Ate (r=0.53, p<0.01). Lo, Ate and Lo&Ate in the chest CAT are reliable parameters that can be used to estimate pulmonary vascular resistance in patients with PH associated with left-to-right shunts.

Exposure of circumflex branches in the tilted, beating porcine heart: echocardiographic evidence of right ventricular deformation and the effect of right or left heart bypass.

OBJECTIVE: In off-pump coronary surgery, exposure of posterior vessels via sternotomy causes deterioration of cardiac function. Changes in ventricular geometry, valve competence, and hemodynamics after retraction of the beating heart were studied. Subsequently, the modifying effect of right or left heart bypass was investigated. METHODS: In six 80-kg pigs, an ultrasound probe was attached to the backside of the left ventricle and the heart was fully retracted with a suction tissue stabilizer. Five pigs underwent additional pump support. RESULTS: During retraction, the right ventricle was squeezed between the pericardium and interventricular septum, thereby decreasing its diastolic cross-sectional area by 62% +/- 6% (P <.001) while, concomitantly, right ventricular end-diastolic pressure increased to 165% +/- 19% (P =.004) of basal values. Stroke volume and mean arterial pressure decreased by 29% +/- 6% and 23% +/- 8% (P =.007 and P =.02, respectively). Left ventricular shape became somewhat elliptic without changes in preload pressure, and its diastolic cross-sectional area decreased by 20% +/- 3% (P =.001). All valves were competent. Right heart bypass restored left ventricular cross-sectional area, stroke volume, and mean arterial pressure. In contrast, left heart bypass increased blood pressure only marginally. CONCLUSIONS: Ninety-degree anterior displacement of the beating porcine heart caused primarily right ventricular dysfunction as a result of mechanical interference with diastolic expansion without concurring valvular incompetence. Right heart bypass normalized stroke volume and mean arterial pressure by increasing left ventricular preload; in contrast, left heart bypass failed to restore systemic circulation.

Influence of the use of a bypass on the results of thoracoabdominal aortic aneurysm surgery.

OBJECTIVES: To evaluate the influence of the use of a bypass on the results of thoracoabdominal aortic aneurysm surgery. METHODS: The results of the repair of 224 thoracoabdominal aortic aneurysms operated upon between 1981 and the end of 1996 were evaluated retrospectively. In 122 cases we used simple cross-clamping (clamp and sew technique) and in 102 cases a left heart bypass (atrio-femoral or aorto-femoral) was the preferred method. Except for the use of cerebrospinal fluid drainage over the last years, the methods of spinal protection were the same in both groups. Renal protection was also identical in both groups. All aneurysms were repaired using the inlay technique. RESULTS: Hospital mortality was 11.2%: 14.7% in cross-clamp group versus 6.8% in the bypass group (p = 0.04). Postoperative dialysis was necessary in 9.8%: 12.7% in the cross-clamp group versus 6.8% in the bypass group (p = 0.108). Paraplegia occurred in 8.4%: 7.4% in the cross-clamp group versus 9.8% in the bypass group (p = 0.517). Using the highly predictive model of Acher, there would have been 33% spinal cord lesions in the bypass group. CONCLUSIONS: Hospital mortality, postoperative dialysis and postoperative spinal cord problems are lowered by the use of a bypass during the repair of thoracoabdominal aortic aneurysms. These results evidence that the use of a bypass is indicated in this complex operation.

Complete myocardial revascularization with left heart bypass without oxygenator on the beating heart.

BACKGROUND: Whereas the complete myocardial revascularization is necessary in high risk group patients, the CABG procedure on the beating heart on circumflex artery still presents a dilemma. METHODS: Between January 1994 and September 1996, we performed complete myocardial revascularization with left heart bypass in 62 patients (54 male, 8 female, mean age: 57) who had absolute or relative contraindications for CPB. RESULTS: The hospital mortality was 3.2%, late mortality was 1.6%. Peroperative MI was seen in 2 patients (3.2%). The mean number of distal anastomosis was 3.6 (ranged 2-6). CONCLUSION: Complete myocardial revascularization on the beating heart can be performed by using left heart bypass (LHBP) without using an oxygenerator safely in high risk patients.

Posterior circulation cerebral infarcts associated with repair of thoracic aortic disruption using partial left heart bypass.

BACKGROUND: Partial left heart bypass is widely used in the repair of traumatic aortic disruptions. We recently encountered two patients with posterior circulation infarctions after repair of traumatic aortic disruptions using heparin-less partial left heart bypass. METHODS/RESULTS: Both patients underwent interposition graft repair of thoracic aortic transections at the level of the isthmus. The first patient developed a left posterior inferior cerebellar artery infarct after a clamp time of 44 minutes. Swelling of this infarct necessitated ventriculostomy placement. The second patient developed a pontine infarct postoperatively after a cross-clamp time of 56 minutes and suffered a persistent left upper extremity paresis. CONCLUSIONS: Partial left heart bypass may have predisposed these two patients to clamp-related embolic events via the left vertebral artery. This experience warrants further surveillance to detect these infarcts which can require neurosurgical intervention. Additionally, the events suggest reconsideration of systemic anticoagulation during aortic cross-clamp times exceeding 30 minutes.

Surgical and long-term outcome of graft replacement of aneurysms of the descending thoracic aorta. Analysis of 28 consecutive cases.

A consecutive series of 28 patients operated on at the Oulu University Hospital during the years 1974-1994 for aneurysms of the descending thoracic aorta is presented. Twenty-five cases were elective and three were operated on as emergencies. Their mean age was 58 years. During the aortic cross-clamp, circulatory support of the lower body, was used in 27 cases as follows: a direct aorto-femoral shunt without a pump (12/28), left-heart bypass (11/28) or femoro-femoral perfusion (4/28). Hospital mortality was 14% (4/28). One patient with a ruptured aneurysm died of renal failure, but there were no other renal complications. None had paraplegia postoperatively. Three had symptoms of paraparesis, but only one of them had a slight permanent discomfort while walking. The mean follow-up time was 100 months, range 2-242 months. Late actuarial survival including hospital mortality, was 65% at 5 years and 41% at 10 years, reflecting the generalized aortic disease with a high risk of very late rupture (4) and other manifestations of atherosclerosis with myocardial infarction (6) or cerebral atherosclerosis (1), the remaining late deaths being unrelated. The efficacy of lower body circulatory support in avoiding peroperative renal and spinal cord ischaemic complications is demonstrated.