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Operative management of aortic arch aneurysms using profound hypothermia and circulatory arrest
Thoracic Aorta I! RESULTS: Group B required a significantly shorter rewarming time (P <0.01), and demonstrated a tendency for the operative and cardiopulmonary bypass times to be shorter, and the peroperative bleeding volumes to be smaller. There was no significant difference between the groups in SVO2 level of the innominate vein blood during SCP, and in the consciousness recovery time postoperativery. In Group B, however, the SCP time showed a significant positive correlation with the consciousness recovery time (P <0.05). The mean urine volume of 101.4 4- 37.8 ml/hr during low flow body perfusion was satisfactory and had a tendency to be larger in Group B. The operative mortalities of Group A and Group B were 17.3% and 0% respectively, and a neurological complication was found in one patient in each group. CONCLUSION: SCP under moderate hypothermia is a useful and reliable method for the surgical treatment of aortic arch aneurysms.
24.11 Continuous Monitoring of Short-latency Somatosensory Evoked Potentials During Open Heart Surgery T. KA WADA, S. NAKAMURA, K. NISHIMURA, T. KOYAMA, S. KAMATA, H. TAKEI, S. FUNAKI and N. YAMA TE, Kawasaki, Japan Usefulness of intraoperative monitoring of somatosensory evoked potentials (SEPs) for the early diagnosis of brain damage is controversial. From 1991 to 1994, SEPs were recorded in 287 consecutive patients undergoing open heart surgery using cardiopulmonary bypass with moderate hypothermia or deep hypothermic circulatory arrest, in order to assess its diagnostic accuracy for brain damage. SEPs (P1 to N2) occurring within 50 ms latency in response to electrical stimulation to the median nerve, were recorded over the contralateral postcentral cortex at 5-min interval using Neuropack-2 (Nihon Koden Co). Normal SEPs were restored in 247 patients postoperatively, however, cerebral infarction had developed in two patients and transient stroke in one with a false negative incidence of 1.2%. On the other hand, three different types of abnormal SEPs were recorded postoperatively; SEPs associated with P1 and N1 absence (subcortical lesion) in four patients, P2 and N2 absence (cortical lesion) in eight patients and flat SEP (diffuse damage) in two patients. Among these 14 patients with abnormal SEPs, seven patients showed no neurologic disturbance, with a false positive incidence of 50%. When normal SEPs are restored during weaning from CPB, the incidence of brain damage would be predicted to be below 5% (sensitivity). In patients demonstrating abnormal SEPs, the incidence of significant disabling brain dysfunction is estimated to be 70% (specificity). 24.12
Transcranial Doppler UltrasonographicEvaluation of Cerebral Circulation During Moderate Hypothermic Cardiopulmonary Bypass in Patients with Cerebrovascular Disease S. KAMIHIRA, T. HONDA, Y. HARA, S. ISHIGURO, H. KURODA, S. OGHI and T. MORI, Yonago, Japan The purpose of this study was to examine the cerebral circulation and metabolism during moderate hypothermic
CARDIOVASCULAR SURGERY SEPTEMBER 1995
cardiopulmonary bypass (CPB) in patients with cerebrovascular disease (CVD). Computed tomography (CT) and single photon emission computed tomography (SPECT) were performed preoperatively in 36 patients. Patients were categorized according to their CT and SPECT findings: 24 patients were included in the normal group, and 12 patients were included in the CVD group. Blood flow velocity in the middle cerebral artery (MCAv) was measured using transcranial Doppler ultrasonography, and cerebral oxygen consumption was estimated by relating the arteriovenous oxygen content difference to the flow velocity (D-CMRO2). MCAv and D-CMRO2 were expressed as a percentage of the values determined at 30 min before CPB. High-dose fentanyl anesthesia was used, and alpha-stat pH strategy (uncorrected for body temperature), moderate hemodilution and nonpulsatile flow pattern were maintained during CPB. In both groups, the flow velocity and D-CMRO2 changed in parallel in proportion to the change in body temperature during the procedure. Thus, there was good correlation between flow velocity and DCMRO2 during CPB. Flow velocity was not influenced by perfusion pressure within the range from 40-90 mmHg, and variations in arterial carbon dioxide tension induced significant changes in flow velocity. In the normal group, the change of PaO2 had no effect on D-CMROz, whereas in the CVD group D-CMRO2 decreased with PaOz increasing at moderate hypothermic steady-state CPB. We conclude that in patients with cerebrovascular disease, cerebral autoregulation to perfusion pressure, coupling between flow and metabolism, and vascular reactivity to arterial carbon dioxide tension, are all maintained during moderate hypothermic nonpulsatile cardiopulmonary bypass. However, a high PaCO2 depresses cerebral oxygen consumption because hypercarbia may cause potentially harmful redistribution of regional cerebral blood flow; away from marginaUy-perfused to otherwise well-perfused areas.
24.13
Operative Management of Aortic Arch Aneurysms using Profound Hypothermia.andCirculatoryArrest M. EHRLICH, M. GRABENWOGER, P. SIMON, G. LA UFER, E. WOLNER and M. HA VEL, Vienna, Austria Between October 1990 and September 1994, 79 patients underwent aortic arch replacement for aneurysmal disease in our institution. Fifty-nine patients had a dissection. Type A (43 acute,16 chronic), and 20 patients (6 acute,14 chronic) had an aortic diameter of more than 6 cm. The patients age (53 male, 26 female) ranged between 16 and 81 years. Primary diagnosis was hypertension (n = 60), Marfan (n = 8), unknown (n = 10) and trauma (n = 1). Total cardiopulmonary bypass was established via femoral artery cannulation. Cortisone and thiopental were given for added cerebral protection. Deep hypothermia, confirmed by isoelectric-EEG, and circulatory arrest were induced in all patients. The aneurysm was opened longitudinally and a full thickness single patch or 'island' of aortic wall, containing the origins of the three arch vessels, was constructed and anastomosed in a continuous fashion to an albumin pretreated graft. Seventy-eight patients survived the operation (intraoperative mortality: 1%). The 30-day mortality was 28% (n = 1 7) in the dissection group, and 15% (n = 3) in the aneurysmal group. Causes of perioperative death in order of frequency
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22nd World Congress of the International Society for Cardiovascular Surgery were: multiorgan failure (n = 12), sepsis (n = 3), stroke (n = 2), bleeding (n = 2) and myocardial infarction (n = 1). The mean cerebral circulatory arrest time was 32 min (range 11-113 rain). In our experiences, profound hypothermia and circulatory arrest have proved to be valuable adjuncts in the treatment of complex reconstructions on the thoracic aorta. 24.14 Aortic Arch Reconstruction - Protection of the Brain
K. TABAYASHI, M. OHMO, T. TOGO, M. SADAHIRO, Y. SHOJI and N. UCNIDA, Sendal, Japan Between January 1987 and August 1994, 98 patients underwent aortic arch reconstruction. Forty-six patients had aortic dissection, and 52 patients had true aortic arch aneurysm. The ages of the patients ranged from 32 to 79 year, with a mean of 65 years. Selective cerebral perfusion (SC) was used during the period of aortic branch occlusion in all cases. During SCP, in-line pressure and cerebral circulatory index (100/1.39 Hb (SaO2-SjvOz)/100) was monitored using a Swan-Ganz Oximetry TD catheter. Pre- and postoperative cerebral function
130
was evaluated using the mini mental slate-Himeji test and the Wechsler adult intelligence scale. Fourteen preoperative, 10 intraoperative and 13 postoperative factors were assessed in order to evaluate the predictive risks for early operative mortality using logistic regression analysis. The average cerebral perfusion time was 115 +_ 55 min at an average esophageal temperature of 19 + 29°C. The average duration of myocardial ischemia was 135 _ 47 min and that of cardiopulmonary bypass was 278 __ 95 min. There were 13 hospital deaths, four in the aortic dissection group and nine in the true aortic aneurysm group. Multivariate logistic regression analysis indicated ischemic heart disease, concomitant CABG and cerebrovascular accident to have significant and independent risks for early mortality. Postoperative cerebrovascular accident occurred in six patients, of which two survived with hemiplegia, while the other four died in a deep coma. There were no significant differences in the mini mental state-Himeji test and the Wechsler adult intelligence scale before and after operation. The 5-year actuarial survival rates for true and dissecting aneurysms were 59.0% and 65.3%, respectively. Replacement of the aortic arch using SCP is a safe procedure with acceptable hospital mortality.
CARDIOVASCULAR SURGERY SEPTEMBER 1995
24.11 Continuous Monitoring of Short-latency Somatosensory Evoked Potentials During Open Heart Surgery T. KA WADA, S. NAKAMURA, K. NISHIMURA, T. KOYAMA, S. KAMATA, H. TAKEI, S. FUNAKI and N. YAMA TE, Kawasaki, Japan Usefulness of intraoperative monitoring of somatosensory evoked potentials (SEPs) for the early diagnosis of brain damage is controversial. From 1991 to 1994, SEPs were recorded in 287 consecutive patients undergoing open heart surgery using cardiopulmonary bypass with moderate hypothermia or deep hypothermic circulatory arrest, in order to assess its diagnostic accuracy for brain damage. SEPs (P1 to N2) occurring within 50 ms latency in response to electrical stimulation to the median nerve, were recorded over the contralateral postcentral cortex at 5-min interval using Neuropack-2 (Nihon Koden Co). Normal SEPs were restored in 247 patients postoperatively, however, cerebral infarction had developed in two patients and transient stroke in one with a false negative incidence of 1.2%. On the other hand, three different types of abnormal SEPs were recorded postoperatively; SEPs associated with P1 and N1 absence (subcortical lesion) in four patients, P2 and N2 absence (cortical lesion) in eight patients and flat SEP (diffuse damage) in two patients. Among these 14 patients with abnormal SEPs, seven patients showed no neurologic disturbance, with a false positive incidence of 50%. When normal SEPs are restored during weaning from CPB, the incidence of brain damage would be predicted to be below 5% (sensitivity). In patients demonstrating abnormal SEPs, the incidence of significant disabling brain dysfunction is estimated to be 70% (specificity). 24.12
Transcranial Doppler UltrasonographicEvaluation of Cerebral Circulation During Moderate Hypothermic Cardiopulmonary Bypass in Patients with Cerebrovascular Disease S. KAMIHIRA, T. HONDA, Y. HARA, S. ISHIGURO, H. KURODA, S. OGHI and T. MORI, Yonago, Japan The purpose of this study was to examine the cerebral circulation and metabolism during moderate hypothermic
CARDIOVASCULAR SURGERY SEPTEMBER 1995
cardiopulmonary bypass (CPB) in patients with cerebrovascular disease (CVD). Computed tomography (CT) and single photon emission computed tomography (SPECT) were performed preoperatively in 36 patients. Patients were categorized according to their CT and SPECT findings: 24 patients were included in the normal group, and 12 patients were included in the CVD group. Blood flow velocity in the middle cerebral artery (MCAv) was measured using transcranial Doppler ultrasonography, and cerebral oxygen consumption was estimated by relating the arteriovenous oxygen content difference to the flow velocity (D-CMRO2). MCAv and D-CMRO2 were expressed as a percentage of the values determined at 30 min before CPB. High-dose fentanyl anesthesia was used, and alpha-stat pH strategy (uncorrected for body temperature), moderate hemodilution and nonpulsatile flow pattern were maintained during CPB. In both groups, the flow velocity and D-CMRO2 changed in parallel in proportion to the change in body temperature during the procedure. Thus, there was good correlation between flow velocity and DCMRO2 during CPB. Flow velocity was not influenced by perfusion pressure within the range from 40-90 mmHg, and variations in arterial carbon dioxide tension induced significant changes in flow velocity. In the normal group, the change of PaO2 had no effect on D-CMROz, whereas in the CVD group D-CMRO2 decreased with PaOz increasing at moderate hypothermic steady-state CPB. We conclude that in patients with cerebrovascular disease, cerebral autoregulation to perfusion pressure, coupling between flow and metabolism, and vascular reactivity to arterial carbon dioxide tension, are all maintained during moderate hypothermic nonpulsatile cardiopulmonary bypass. However, a high PaCO2 depresses cerebral oxygen consumption because hypercarbia may cause potentially harmful redistribution of regional cerebral blood flow; away from marginaUy-perfused to otherwise well-perfused areas.
24.13
Operative Management of Aortic Arch Aneurysms using Profound Hypothermia.andCirculatoryArrest M. EHRLICH, M. GRABENWOGER, P. SIMON, G. LA UFER, E. WOLNER and M. HA VEL, Vienna, Austria Between October 1990 and September 1994, 79 patients underwent aortic arch replacement for aneurysmal disease in our institution. Fifty-nine patients had a dissection. Type A (43 acute,16 chronic), and 20 patients (6 acute,14 chronic) had an aortic diameter of more than 6 cm. The patients age (53 male, 26 female) ranged between 16 and 81 years. Primary diagnosis was hypertension (n = 60), Marfan (n = 8), unknown (n = 10) and trauma (n = 1). Total cardiopulmonary bypass was established via femoral artery cannulation. Cortisone and thiopental were given for added cerebral protection. Deep hypothermia, confirmed by isoelectric-EEG, and circulatory arrest were induced in all patients. The aneurysm was opened longitudinally and a full thickness single patch or 'island' of aortic wall, containing the origins of the three arch vessels, was constructed and anastomosed in a continuous fashion to an albumin pretreated graft. Seventy-eight patients survived the operation (intraoperative mortality: 1%). The 30-day mortality was 28% (n = 1 7) in the dissection group, and 15% (n = 3) in the aneurysmal group. Causes of perioperative death in order of frequency
129
22nd World Congress of the International Society for Cardiovascular Surgery were: multiorgan failure (n = 12), sepsis (n = 3), stroke (n = 2), bleeding (n = 2) and myocardial infarction (n = 1). The mean cerebral circulatory arrest time was 32 min (range 11-113 rain). In our experiences, profound hypothermia and circulatory arrest have proved to be valuable adjuncts in the treatment of complex reconstructions on the thoracic aorta. 24.14 Aortic Arch Reconstruction - Protection of the Brain
K. TABAYASHI, M. OHMO, T. TOGO, M. SADAHIRO, Y. SHOJI and N. UCNIDA, Sendal, Japan Between January 1987 and August 1994, 98 patients underwent aortic arch reconstruction. Forty-six patients had aortic dissection, and 52 patients had true aortic arch aneurysm. The ages of the patients ranged from 32 to 79 year, with a mean of 65 years. Selective cerebral perfusion (SC) was used during the period of aortic branch occlusion in all cases. During SCP, in-line pressure and cerebral circulatory index (100/1.39 Hb (SaO2-SjvOz)/100) was monitored using a Swan-Ganz Oximetry TD catheter. Pre- and postoperative cerebral function
130
was evaluated using the mini mental slate-Himeji test and the Wechsler adult intelligence scale. Fourteen preoperative, 10 intraoperative and 13 postoperative factors were assessed in order to evaluate the predictive risks for early operative mortality using logistic regression analysis. The average cerebral perfusion time was 115 +_ 55 min at an average esophageal temperature of 19 + 29°C. The average duration of myocardial ischemia was 135 _ 47 min and that of cardiopulmonary bypass was 278 __ 95 min. There were 13 hospital deaths, four in the aortic dissection group and nine in the true aortic aneurysm group. Multivariate logistic regression analysis indicated ischemic heart disease, concomitant CABG and cerebrovascular accident to have significant and independent risks for early mortality. Postoperative cerebrovascular accident occurred in six patients, of which two survived with hemiplegia, while the other four died in a deep coma. There were no significant differences in the mini mental state-Himeji test and the Wechsler adult intelligence scale before and after operation. The 5-year actuarial survival rates for true and dissecting aneurysms were 59.0% and 65.3%, respectively. Replacement of the aortic arch using SCP is a safe procedure with acceptable hospital mortality.
CARDIOVASCULAR SURGERY SEPTEMBER 1995