Normothermic Extracorporeal Circulation Research Articles

Re-hybrid thoracic stent graft implantation with total aortic arch debranching in urgent procedure: case report

INTRODUCTION: Implementation of emergency endovascular aortic repair provides an opportunity to treat complicated acute aortic syndromes involving descending aorta. CASE REPORT: A 40-year-old man with a history of aortic coarctation surgical repair as a child and an anastomosis aneurysm repair with a double endovascular stent graft implantation with hemi-arch transposition was urgently admitted with intensifying shortness of breath and hoarseness. A computed tomography study confirmed a blood leak into an aneurysm sac in proximal landing zones of implanted stent grafts (Type I endoleak). Therefore, he qualified for hybrid surgery. First, the ascending aorta brachiocephalic trunk was anastomosed with a 12 mm vascular prosthesis from an upper mini-sternotomy. In the next step, normothermic extracorporeal circulation was necessary to prevent cerebral circulation. Finally, a GORE stent graft (Gore Medical, Flagstaff, AZ, USA) was implanted with a proximal landing zone directly behind the anastomosis site of the vascular prosthesis and ascending aorta. The hospital course was uncomplicated, and the patient was discharged home 5 days after the procedure. CONCLUSIONS: Complicated aortic pathologies requiring emergent interventions can be treated by a hybrid approach utilizing multistep surgical and endovascular techniques achieving optimal results.

P334 RARE CASE OF PAPILLIFEROUS FIBROELASTOMA ON AORTIC VALVE

Abstract Cardiac tumors are rare neoplastic processes that can arise from any tissue in the heart. They are divided into primitive (benign or malignant) and metastatic (always malignant). The prevalence of cardiac tumors ranges from 0.002% to 0.28%, of which most are benign. Papillary fibroelastoma is the third most common heart cancer and the most frequent heart valve cancer. We describe the case of a 50–year–old ex–smoker patient with a recent history of recurrent right popliteal – tibial femoral thrombectomy and subsequent percutaneous angioplasty. He arrived in the emergency room for ischemic ulcers and fistulization of the right lower limb, for which he was admitted to the Vascular Surgery Department. The patient came to our observation for appearance during the hospitalization of episodes of chest pain at rest with irradiation to the left upper limb and spontaneous regression. The physical examination, blood pressure, blood chemistry tests, chest X–ray and ECG were normal. Transthoracic and transesophageal echocardiography showed a left ventricle with good contractile function, a tricuspid aortic valve with cusp movement preserved with an oval mass, hypoechoic, with well–defined margins, adhering to the ventricular surface of the right coronary cusp, conditioning insufficiency of mild degree. This image was suggestive for papillary fibroelastoma. In addition, in anticipation of cardiac surgery, a coronary CT was performed which confirmed the presence of an oval, hypodense mass and the absence of significant coronary lesions. The absence of fever, increased inflammation and leukocytosis indices made it possible to exclude an endocarditic origin of the lesion, just as the echocardiographic and radiological characteristics eliminated the suspicion of thrombosis. The patient underwent cardiac surgery via longitudinal median sternotomy, in normothermic extracorporeal circulation (CEC). The mass was then excised, preserving the native aortic valve. Postoperative follow–up with transesophageal echocardiography showed no signs of aortic insufficiency. The postoperative course was uneventful. The histological examination of the lesion confirmed the diagnosis of papillary fibroelastoma. At the follow–up after about 3 years the patient was asymptomatic and without echocardiographic signs of local recurrence.

Pulmonary valve replacement in patients with corrected tetralogy of Fallot.

Introduction: Development of pulmonary insufficiency in patients with surgically corrected tetralogy of Fallot (TOF) may lead to severe right heart failure with serious consequences. We herein present our experience with pulmonary valve replacement (PVR) in these patients. Methods: From 2005-2013, 99 consecutive patients (71 males/28 females, mean age 38±8 years), underwent PVR after 7 to 40 (mean 29 ± 8) years from the initial correction. Seventy nine of the symptomatic patients presented in NYHA II, 14 in III and 2 in IV. All underwent PVR with a stented bioprosthetic valve, employing a beating heart technique with normothermic extracorporeal circulation support. Concomitant procedures included resection of aneurysmal outflow tract patches (n = 37), tricuspid valve annuloplasty (n = 36), augmentation of stenotic pulmonary arteries (n = 9), maze procedure (n = 2) and pulmonary artery stenting (n = 4). Results: There were 2 perioperative deaths (2%). One patient developed sternal dehiscence requiring rewiring. Median ICU and hospital stay was 1 and 7 days respectively. Postoperative echocardiography at 6 and 12 months showed excellent bioprosthetic valve performance, significant decrease in size of the right cardiac chambers and reduction of tricuspid regurgitation (TR) in the majority of the patients. At mean follow-up of 3.6 ± 2 years, all surviving patients remain in excellent clinical condition. Conclusion: Probability of reoperation for pulmonary insufficiency in patients with surgically corrected TOF increases with time and timely PVR by preventing the development of right heart failure is crucial for long-term survival. Current bioprosthetic valve technology in combination with the beating heart technique provides excellent immediate and short-term results. Further follow-up is necessary to evaluate long-term outcome.

Combined in situ hypothermic liver preservation and cardioplegia for resection of hepatoblastoma with intra-atrial extension in a 3 year old child

Abstract Cure of hepatoblastoma requires complete macro- and microscopic resection of the tumor, without tumor rupture. In case of hepatoblastoma with intra-atrial tumor extension (ITE), “en bloc” resection of the hepatic tumor and ITE, with minimal risk of postoperative liver failure, constitutes a surgical challenge. We report on a 3 year old child with hepatoblastoma of the right liver lobe, and ITE through the upper Inferior Vena Cava. Initial chemotherapy (SIOPEL IV HR) induced good response, but tumor persisted inside the right atrium with tight adhesions to the cardiac wall. “En bloc” right extended hepatectomy and removal of the ITE with reconstruction of the atrial and caval wall with autologous pericardial patch was performed under normothermic extracorporeal circulation and cardioplegia, combined with in situ hypothermic liver preservation of the remaining left liver. Complete tumor resection was achieved without tumor rupture. Postoperative liver function was immediately good and adjuvant chemotherapy was resumed per protocol. Eleven months after the end of treatment the child is in complete tumor remission. In children with hepatic tumor and ITE, combination of normothermic extracorporeal circulation with cardioplegia and in situ hypothermic liver preservation allows “en bloc” extended hepatectomy and removal of ITE, with limited risk of postoperative liver failure.

Multiple electrode aggregometry for the assessment of acquired platelet dysfunctions during extracorporeal circulation.

There have been many reports on how the usage of extracorporeal circulation (ECC) is independently associated with the induction of platelet dysfunctions. The aim of the present investigation was to study the capability of the multiple electrode aggregometry (MEA) using the Multiplate (Roche AG, Grenzach, Germany) device to reflect the extent of ECC-associated platelet dysfunctions. The study population consisted of patients who were treated with either hypothermic (cardiopulmonary bypass [CPB]) or normothermic (extracorporeal membrane oxygenation) ECC. Hemostatic analyses included conventional laboratory coagulation tests and aggregometric measures following stimulation with different agonists using MEA. The area under the aggregation curve in the ADPtest (ex vivo adenosine diphosphate induced platelet aggregation) of the MEA was defined as the primary end point. The analyses were performed before the usage of ECC (baseline) and 90 minutes (T1), 120 minutes (T2), 150 minutes (T3), and 180 minutes (T4) after the usage of ECC. In the hypothermic ECC group, additional hemostatic analyses were performed after the patient's postoperative admission to the intensive care unit (T5). Periprocedural data and results of other hemostatic testing were defined as secondary end points. A total of n = 40 patients were assessed for eligibility and n = 25 patients were finally enrolled into the study (hypothermic ECC group: n = 20; normothermic ECC group: n = 5). The extent of ADP-induced platelet aggregation decreased significantly between baseline and consecutive measuring points during hypothermic ECC and remained unchanged between T4 and T5. In the normothermic ECC group, ADP-induced aggregability was significantly lower at T1 compared with baseline and remained unchanged from T1 onward. Data from the present study indicate that ex vivo ADP-induced platelet aggregation in MEA reflects the time-dependent extent of ECC-induced platelet dysfunction.

S1P1 receptor modulation preserves vascular function in mesenteric and coronary arteries after CPB in the rat independent of depletion of lymphocytes.

BackgroundCardiopulmonary bypass (CPB) may induce systemic inflammation and vascular dysfunction. Sphingosine 1-phosphate (S1P) modulates various vascular and immune responses. Here we explored whether agonists of the S1P receptors, FTY720 and SEW2871 improve vascular reactivity after CPB in the rat.MethodsExperiments were done in male Wistar rats (total n = 127). Anesthesia was induced by isoflurane (2.5–3%) and maintained by fentanyl and midazolam during CPB. After catheterization of the left femoral artery, carotid artery and the right atrium, normothermic extracorporeal circulation was instituted for 60 minutes. In the first part of the study animals were euthanized after either 1 hour, 1 day, 2 or 5 days of the recovery period. In second part of the study animals were euthanized after 1 day of postoperative period. We evaluated the contractile response to phenylephrine (mesenteric arteries) or to serotonin (coronary artery) and vasodilatory response to acethylcholine (both arteries).ResultsContractile responses to phenylephrine were reduced at 1 day recovery after CPB and Sham as compared to healthy control animals (Emax, mN: 7.9±1.9, 6.5±1.5, and 11.3±1.3, respectively). Mainly FTY720, but not SEW2871, caused lymphopenia in both Sham and CPB groups. In coronary and mesenteric arteries, both FTY720 and SEW2871 normalized serotonin and phenylephrine-mediated vascular reactivity after CPB (p<0.05) and FTY720 increased relaxation to acetylcholine as compared with untreated rats that underwent CPB.ConclusionPretreatment with FTY720 or SEW2871 preserves vascular function in mesenteric and coronary artery after CPB. Therefore, pharmacological activation of S1P1 receptors may provide a promising therapeutic intervention to prevent CPB-related vascular dysfunction in patients.

Thrombose d’oxygénateur en l’absence de résistance à l’héparine mais en présence d’une maladie de Vaquez

A 55-year-old male with a history of positive HIV serology and polycythemia vera underwent coronary artery bypass graft surgery with normothermic extracorporeal circulation. Following heparin administration the activated clotting time (ACT) was 633 seconds (Hemocron® with kaolin). Lower than expected arterial and venous oxygen partial pressures together with high pressure (350mmHg) in the arterial line upstream of the oxygenator were observed. Because of these signs the oxygenator was changed during the procedure. The outcome was uneventful. Electronic microscopic examination of the oxygenator membrane and thermic exchanger revealed fibrin and platelet deposits. Similar cases are described in the literature during polycythemia vera. Therefore the prevention might be a preoperative treatment with antiplatelet therapy in polycytemia vera.

Platelet anaesthesia during extracorporeal circulation: Differential effects of GP IIb/IIIa blockers on platelet activation marker P-selectin expression at hypothermia

Introduction Blood contact with artificial surfaces of extracorporeal circulation (ECC) and hypothermia as applied in cardiac surgery cause platelet dysfunction possibly followed by bleeding complications. “Platelet anaesthesia” is a pharmacological strategy to protect platelets against ECC-induced damage using a GP IIb/IIIa blocker, which should be short acting to achieve maximal therapy control thereby avoiding post-ECC haemorrhage. However, GP IIb/IIIa blockers can paradoxically induce platelet activation, which may limit their efficiency as anti-platelet drugs. This in-vitro study investigated potentially platelet-activating effects of short-acting GP IIb/IIIa blockers during normothermic and hypothermic ECC. Materials and methods Control (untreated) and treated (using either FK633 [half-life: 0.52 h], tirofiban [half-life: 1.5–2 h], or eptifibatide [half-life: 1.5 h]) heparinized blood was circulated in an ECC-model at normothermia (37 °C) and hypothermia (18 °C). Percentages of platelet aggregates and P-selectin-expressing (activated) platelets, platelet-counts and Thrombin–Antithrombin (TAT) complex formation were determined before (baseline) and after ECC. Statistical analysis was performed using multifactorial ANOVA after log-transforming the data. Results GP IIb/IIIa blockade inhibited ECC-induced platelet aggregation and platelet loss and decreased P-selectin expression at normothermia. During hypothermic ECC P-selectin was decreased by tirofiban but augmented by FK633 and eptifibatide. TAT formation was only decreased by FK633. Conclusions Especially regarding its ultra-short half-life FK633 has the best properties for platelet protection during normothermic ECC. However, at hypothermia FK633 and eptifibatide induce platelet activation. In relation with “platelet anaesthesia” possible hypothermia-associated prothrombotic side effects of GP IIb/IIIa blockers should be considered.

Determinants of cerebral oxygenation during normothermic extracorporeal circulation

Determinants of cerebral oxygenation during normothermic extracorporeal circulation

In vivo effects of hypothermia on the microcirculation during extracorporeal circulation

Induced hypothermia has been shown to be protective during cardiac surgery, but also in traumatic, ischemic, burn, and neurological injury. In previous in vivo animal experiments, we documented increased leukocyte/endothelial (L/E) cell interaction following normothermic extracorporeal blood circulation (ECC). This study was carried out to investigate whether reduced core temperature during ECC affects the damage to the microcirculation as evidenced by leukocyte adherence and edema formation. Intravital fluorescence microscopy was used on the dorsal skinfold chamber preparation in Syrian golden hamsters. ECC was introduced via a micro-rollerpump (1 ml/min) and a 60 cm silicon tube (1mm inner diameter) shunted between the carotid artery and the jugular vein after application of 300IE Heparin/kg per body weight. Experiments were performed in chronically instrumented, awake animals (age 10-14 weeks, weight 65-75 g). Animals of the experimental group were cooled to 18 degrees C body temperature while ECC, followed by a rewarming period (n=7), controls experienced ECC under normothermia (37 degrees C, n=7). 30 min ECC at 18 degrees C resulted in a decrease of rolling and adherent leucocytes (stickers) in postcapillary venules after 1, 4 and 8h compared with the control group (119+/-46 vs. 274+/-113 n/mm2, P<0.05, mean+/-SD; n=7 in each group). Functional capillary density was significantly reduced during hypothermia (80+/-16 vs. 148+/-16 cm/cm2, P<0.05), but restored after rewarming. In contrast, edema formation was markedly increased during hypothermia. Hypothermia during ECC significantly reduced L/E cell interaction in the early post-ECC period. Hypothermia markedly reduced microvascular perfusion, but was completely restored upon rewarming. Despite a reduced number of adherent leukocytes, no protection of endothelial barrier function was seen as a consequence of induced hypothermia.

Changes in coronary vessel resistance during postischemic reperfusion and effectiveness of nitroglycerin

Objective: Microvascular incompetence after ischemia and reperfusion may compromise the normal postischemic coronary perfusion and additionally jeopardize the recovery of the myocytes. We investigated whether such a form of acute endothelial dysfunction occurs in the routine operative setting despite the use of protective measures. For this purpose, we measured pressure-flow relations in the coronary vasculature during heart operations before and after ischemia and after reperfusion and their reaction to the nitric oxide donor nitroglycerin. Methods: Forty-eight patients with a low risk profile scheduled for routine coronary artery bypass surgery were included. During normothermic extracorporeal circulation, the fibrillating heart was completely excluded from bypass by clamping of the ascending aorta and snaring of the caval veins. It was relieved of blood by opening the right atrium and venting the left atrium and ventricle to avoid distention. The coronary vessels were perfused under controlled flow, and the perfusion pressures were monitored. This protocol was performed in 24 patients before and immediately after ischemia and after a reperfusion period. Results: Compared with the preischemic control, vascular resistance was decreased by 17% (P ||.003) immediately after ischemia but increased again by 46% (P ||.0001) during an average of 25 minutes of reperfusion and, even more important, by 23% (P ||.028) in comparison with the preischemic values. In two groups of 12 patients, nitroglycerin was added to the perfusate either in a dosage of 3 μg · kg · min–1 or as a bolus injection of 2 mg. Low-dose nitroglycerin did not reduce the elevated postreperfusion resistances significantly, but bolus injection did (P ||.0002). Coronary vessel resistance increased during reperfusion in particular in patients with a history of hypertension. Conclusion: Coronary vasoconstriction during postischemic reperfusion is regularly present in the routine operative setting in cardiac surgery, despite myocardial protection measures. The amount of vasoconstriction varies considerably and is particularly increased in patients with hypertension. The nitric oxide donor nitroglycerin can normalize the elevated resistances, but only in high dosages. This demonstrates a preserved ability of vascular smooth muscle to relax. The phenomenon had no sequelae in our low-risk patients having elective operations. However, it may gain significance in the case of severe left heart hypertrophy and in patients at risk with both a postoperative low-output syndrome and reduced mean arterial pressures during reperfusion.J Thorac Cardiovasc Surg 2001;122:1011-8

Cardiopulmonary bypass, myocardial management, and support techniques Changes in autonomic response of the cerebral circulation after normothermic extracorporeal circulation

Patients who undergo cardiopulmonary bypass frequently have neuropsychologic dysfunction. This study was undertaken to determine whether altered cerebral perfusion and vascular responses may in part lead to these neuropsychologic changes. Pigs were placed on normothermic cardiopulmonary bypass for 2 hours. Basal cerebral blood flow and in vivo responses to administration by internal carotid artery of neuronally released vasoactive substances were evaluated before and 5 to 15 minutes after termination of cardiopulmonary bypass. Another group of pigs were placed on cardiopulmonary bypass for 2 hours and then perfused off bypass for 1 additional hour. In vitro responses of cerebral arterial microvessels (100 to 175 μm) from both groups were examined in a pressurized (40 mm Hg) no-flow state with videomicroscopy. Vessels from uninstrumented pigs served as control preparations for in vitro studies. Cerebrovascular resistance and cerebral perfusion were maintained constant during cardiopulmonary bypass and after separation from bypass. The internal carotid artery infusion of acetylcholine (cholinergic agonist) caused increased internal carotid artery blood flow before cardiopulmonary bypass but decreased blood flow after cardiopulmonary bypass. After 2 hours of cardiopulmonary bypass, the increase in internal carotid artery blood flow induced by isoproterenol (a β-adrenoceptor agonist) was reduced, whereas the response to sodium nitroprusside (a guanylate cyclase activator) was unchanged. In vitro acetylcholine-induced microvascular vasodilation was converted to a contractile response and isoproterenol elicited less relaxation after 2 hours of cardiopulmonary bypass. One hour of cerebral perfusion after cardiopulmonary bypass caused a further reduction in isoproterenol-induced relaxation but had no further effect on the cholinergically mediated response. In vitro relaxation responses to sodium nitroprusside and forskolin (an adenylate cyclase activator) were similar in all experimental groups, suggesting that second-messenger mechanisms remain intact after normothermic cardiopulmonary bypass. In conclusion, basal cerebrovascular resistance and internal carotid artery blood flow are maintained if the systemic circulation and pressure are supported with fluid administration after cardiopulmonary bypass. Agonist-induced vasodilation of cerebral microvessels to cholinergic and β-adrenoceptor stimulation are selectively impaired after normothermic cardiopulmonary bypass, whereas second-messenger mechanisms remain intact. (J T horac C ardiovasc S urg 1996;112:450-61)

Moderate hypothermia reduces cardiopulmonary bypass-induced impairment of cerebrovascular responses to platelet products

The purpose of this study was to determine whether cerebral cortical microvascular responses to platelet-derived vasoactive substances are altered after normothermic cardiopulmonary bypass (CPB), and whether these alterations are modified by moderate hypothermia. Pigs were placed on normothermic CPB (37 degrees C) for 2 hours and then perfused off CPB with normothermic blood for either 15 minutes (n = 8) or 60 minutes (n = 6). Another group was placed on moderately hypothermic CPB (25 degrees C) for 2 hours and then perfused off CPB at 37 degrees C for 15 minutes (n = 6). Alphastat pH management was used. In vitro responses of isolated cortical cerebral arterioles (90 to 170 microns internal diameter) to platelet-derived vasoactive substances were examined in a pressurized no-flow state with videomicroscopy. Microvessels from noninstrumented pigs (n = 14) were used as controls for in vitro studies. Cerebrovascular resistance and internal carotid artery blood flow were similar 15 minutes after CPB in both normothermic and hypothermic groups. However, relaxations of microvessels to adenosine 5' diphosphate or serotonin were reduced in vessels from both groups. One hour of after CPB cerebral perfusion did not change this pattern of altered vascular reactivity. Hypothermia caused a partial but significant reduction in impairment of responses to adenosine 5' diphosphate and serotonin. Microvascular relaxation to the endothelium-independent agent sodium nitroprusside and contraction to a thromboxane A2 analog were similar in all experimental groups, suggesting normal vascular smooth muscle responsiveness. This study demonstrates that normothermic extracorporeal circulation reduces endothelium-dependent relaxation responses to products of platelet activation in the cerebral microcirculation. Moderate hypothermia attenuates the CPB-induced impairment of endothelium-dependent relaxation, but has no effect on baseline cerebral blood flow after rewarming.

Surgical treatment of cardiac arrhythmias

This report describes 20 consecutive patients who underwent surgical procedures for treatment of cardiac arrhythmias. 16 patients have been operated for WPW syndrome, always using the epicardial approach, without extracorporeal circulation. Three patients underwent surgery for atrio-ventricular nodal reentrant tachycardia, using a discrete perinodal cryotreatment, during normothermic extracorporeal circulation. In one case we used cryoablation of the atrial myocardium below the coronary sinus to treat atrial flutter. This operation was performed under normothermic extracorporeal circulation. In our observations, there was no early or late death; postoperative complications developed in 1 patient (5%) due to pericarditis. Ablation of the AP was completely successful in all the cases (100%) operated for WPW as well as for AVNRT syndromes and atrial flutter.

Rupture of the right ventricular free wall. An unusual complication of mediastinitis after cardiac surgery.

Of 2171 patients who underwent open heart surgery between 1981 and 1986, 41 (1.8%) developed postoperative mediastinitis and were treated by closed irrigation drainage or open chest therapy. Six patients, (mean age 59 years) developed rupture of the right ventricular free wall. The primary procedures were: resection of akinetic fibrous plaque (2), mitral valve replacement (1), coronary bypass grafting (1), removal of a left atrial myxoma (1) and repair of post-infarction rupture of the left ventricle (1). In 2 patients, rupture occurred in the operating theatre during revision of the irrigation drainage. Both patients died after repair. In 4 patients, rupture occurred during coughing. One died before surgery. In the 3 other cases, the defects were repaired either by direct suture (2 patients) or with a pericardial patch (1 patient) with the aid of normothermic extracorporeal circulation. Three days later, a muscular flap (pectoral or dorso-lumbar) was mobilized to protect the mediastinal viscera. All 3 patients are alive and well. When bleeding occurs during treatment of mediastinitis, an immediate exploration with extracorporeal circulation to close the defect should be considered.

Brain hyperperfusion during cardiac operations: Cerebral blood flow measured in man by intra-arterial injection of xenon 133: Evidence suggestive of intraoperative microembolism

Cerebral blood flow (CBF) was measured by intra-arterial injection of xenon 133 in 29 patients during cardiac operations. Marked changes occurred in all patients. A normal and significant correlation with temperature and plasma PCO2 (p less than 0.01) support the reliability of the method. Mean CBF measured between sternotomy and the onset of extracorporeal circulation (ECC) was 38 ml/100 gm . min. The first minute of ECC was associated with a decrease in CBF in nine of 12 patients (p less than 0.02). During steady-state hypothermic ECC (temperature 29 degrees C), CBF increased unexpectedly to 64 ml/100 gm . min (p less than 0.01). Following rewarming steady-state normothermic ECC, mean CBF decreased to 42 ml/100 gm . min with signs of impairment of cerebral autoregulation. Ten and 20 minutes after termination of ECC, mean CBF was 40 and 41 ml/100 gm . min, respectively. Arterial PCO2 was found to be important in regulating CBF. The cerebral autoregulation maintained CBF down to arterial pressures of around 55 mm Hg. Below this level, CBF was significantly correlated with perfusion pressure (p less than 0.01). Multiple small emboli with a hyperemic border zone could cause a brain hyperperfusion, as seen in our patients during bypass. Measurements of CBF during ECC hold promise as a guide toward safer cardiac operations.

Heamodynamic studies of liver and portal system under normothermic extracorporeal circulation

Heamodynamic studies of liver and portal system under normothermic extracorporeal circulation