U Yetkin, H Ya?a, ? Yürekli, A Özelçi, A Gürbüz
cardiopulmonary bypass, carotid artery stenosis, coronary artery disease, hypothermia.
U Yetkin, H Ya?a, ? Yürekli, A Özelçi, A Gürbüz. Combined Coronary Artery Bypass Surgery and Carotid Artery Surgery With Utility of Mild Hypothermia. The Internet Journal of Thoracic and Cardiovascular Surgery. 2006 Volume 11 Number 1.
Mild hypothermia during carotid surgery for patients with a unilateral critical stenosis and contralateral total occlusion of the carotid arteries is safe and protects cerebral function in the early and late postoperative periods.
We aimed to determine whether mild hypothermia during combined coronary artery bypass surgery and carotid artery surgery improves outcomes in a patient with unilateral critical stenosis in proximal internal carotid artery and total occlusion on the right side.
Because therapeutic hypothermia has been found to be advantageous in many cardiovascular surgical procedures, and perioperative neurological events occur more often in patients with bilateral critical carotid artery disease, we postulated that hypothermia could improve the outcomes of carotid artery surgery in patients with unilateral critical stenosis and contralateral total carotid occlusion.
Atherosclerosis is a generalized vascular disease so many patients have significant atherosclerotic stenosis at coronary arteries and carotid. Stenosis rate is between 2.4 % and 22% for extracranial arteries in the patients who are admitted for coronary artery surgery(1). Stroke's etiology is primarily vascular, with only 5% of cases arising from nonvascular causes (2). Carotid artery occlusive disease is responsible for approximately 20% to 30% of strokes and carotid endarterectomy (CEA) has been proven effective in reducing this risk of stroke in symptomatic and asymptomatic patients with >60% carotid stenosis (3,4,5). Patients with bilateral carotid artery disease, especially those with unilateral stenosis and contralateral total occlusion, are at particularly high risk for perioperative neurologic events. Previous studies found that mild hypothermia could prevent neuronal ischemia and stroke during surgical procedures on arteries that supply the brain, especially with extended occlusive lesions on both internal carotid arteries (6). Hypothermia effectively reduces brain metabolism. Mild hypothermia reduces cerebral injury in a variety of laboratory models and clinical situations.
Our case was a 63-year-old male. He had stroke anamnesis going on for 2 months. At admission to our clinic, he was hemiparetic on the left and his medical history revealed diabetes mellitus and hypertension.He was suffering from chest pain for one month. After the investigations related with this symptom the diagnosis of coronary artery disease was put and surgical approach was indicated. Therefore he was admitted to our clinic. His coronary angiography revealed subsequent and showed 3 vessels disease (Figures 1 and 2).
Selective bilateral carotid arteriogram performed concomitantly with coronary angiography revealed total occlusion of right internal carotid artery and 80 to 90% stenotic lesions of right internal carotid artery.
His transthoracic echocardiography showed minimal aortic and tricuspid insufficiencies and pulmonary arterial pressure was measured as 35 mmHg. Left ventricular ejection fraction was 64%. Blood pressure values were in the normal range. The patient had no significant changes in standard biochemical findings on admission. He was a nonsmoker. The cholesterol and triglyceride levels were within the high range. Color Doppler ultrasound showed that venous circulation in her left lower extremity was normal.
He was operated under endotracheal general anesthesia and in supine position. The left carotid artery was reached by a longitudinal incision medial to the sternocleidomastoid muscle and the internal and external carotid arteries were exposed. Following a median sternotomy,pericardium was opened longitudinally. After heparinization, extra-corporeal circulation is established between the venae cavae and the ascending aorta. When the patient was cooled down to 32-33°C, the Gott shunt was replaced by opening artery (a temporary intraluminal shunt was inserted). Left carotid endarterectomy was performed on the internal carotid artery and the arteriotomy was closed primarily using continuous polydioxanone 7-0 sutures (Figures 5 and 6).
A cross clamp was placed on aorta and by antegrade intermittant isothermic blood cardioplegia from aortic root,cardiac arrest was established.Hypothermia was moderate (28ºc). Aortoconary bypass was established by using the right great saphenous vein prepared as a graft.Three anastomosis(LAD,CxOM1 and RCA)were performed. He did not require inotropic support during weaning from cardiopulmonary bypass and early postoperative period. The volume of blood transfused was two units. The quantity of mediastinal drainage was 550 cc.He was extubated after an intubation of 8 hours and stayed in the intensive care for 2 days. The hospital stay was 7 days. Our case had no neurological recurrent symptoms as TIA or stroke, or cardiac complaints as angina and they were neurologically and cardiacally asymptomatic during late postop period. Carotid Doppler ultrasound performed on the two month postoperative visit showed no restenosis.
It is believed that carotid lesions increase the risk of neurological complications after coronary artery revascularization and generally accepted surgical strategy is simultaneous operation (7). Simultaneous surgical approach to critical carotid artery stenosis and significant coronary arterial disease is recently performed in many centers, popularized after first applications of Bernhard and his colleagues in 1972 (8).
Combined interventions (first carotid endarterectomy, then median sternotomy and CABG) during a single period of anesthesia and concomitant interventions (first carotid endarterectomy and then CABG under cardiopulmonary bypass and moderate hypothermia) are two different options defined (9,10).
Trachiotis, Pfister, and Akins and his colleagues reported that combined interventions of carotid endarterectomy and CABG are very effective in reducing the neurological and myocardial complications (11,12).
Hypothermia was proposed to prevent neuronal ischemia and stroke during surgical procedures on arteries that supply the brain, especially with extended occlusive lesions on both internal carotid arteries (6). Several clinical studies reported benefits of hypothermia in patients undergoing combined carotid artery and coronary surgery (4,5,10,13,14). Multiple pathophysiological mechanisms, including excitotoxicity, oxygen radical production, intracellular signaling cascades, membrane stabilization, activation of protein kinases, cytoskletal breakdown, and early gene expression are all sensitive to mild temperature variations (15). Mild hypothermia ameloriates, and mild hyperthermia exacerbates, ischemic–induced neuronal injury (16). The classical mechanism proposed for neuronal protection by hypothermia is the reduction of oxygen and glucose consumption caused by reduction in the rates of enzymatic reactions. Mechanisms involved include reduction of ischaemia-induced excitatory neurotransmitter increase (17), effects on ion homeostasis and membrane permeability, recovery of post-ischemic protein synthesis (18), prevention of protein kinase CD down-regulation and the consumption of free radical scavengers in the brain tissue. However, several studies have also found intraoperative hypothermia to adversely affect coagulation, lead to surgical wound infections and morbid cardiac events. It also alters drug metabolism and may increase time to discharge, increase patient discomfort, and induce shivering (19). Despite these disadvantages, some surgeons suggest the cardiopulmonary bypass with accompanying hypothermia and hemodilution adds a protective effect in patients undergoing carotid endarterectomy (4).
Yildirim, Arsan and their colleagues performed carotid endarterectomy under cardiopulmonary bypass on beating heart in their series, thus acquiring additional cerebral protection via hemodilution, hypothermia and heparinization (20).They emphasized that cerebral functions could be better protected via moderate hypothermia by decreasing oxygen consumption of cerebral tissue and preventing deposition of anoxic metabolites. They reported that body temperature was kept around 30ºC in all patients.Although there are controversies regarding optimal mean arterial pressure for cerebral protection under cardiopulmonary bypass, it was reported that maintenance of perfusion pressure between 70 and 90 mmHg would be safe, particularly for patients with carotid arterial disease (9). Tufo and his colleagues reported that risk of neurological accidents increase four times when blood pressure remains below 50 mmHg more than 10 minutes (21).
Evagelopulos and his colleagues, in their series of 313 cases, prepared the carotid arteries first, followed by median sternotomy, systemic heparinization, standard cannulation and cooling down to 30ºC; then performed carotid endarterectomy and venous patch-plasty. With this technique, early mortality rate was found as 8.9% (4.2% cardiac in origin) (22).
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