Progress in treatment of aneurysms of the aortic arch

Congenital Heart Surgery Nomenclature and Database Project: aortic aneurysm, sinus of Valsalva aneurysm, and aortic dissection

The extant nomenclature for aortic aneurysms, sinus of valsalva aneurysms, and aortic dissections is reviewed for the purpose of establishing a unified reporting system. The subject was debated and reviewed by members of the STS-Congenital Heart Surgery Database Committee and representatives from the European Association for Cardiothoracic Surgery. All efforts were made to include all relevant nomenclature categories using synonyms where appropriate. Classification was based on morphology, histology, anatomic location, etiology, and acuity. A comprehensive database set is presented that is based on a hierarchical scheme. Data are entered at various levels of complexity and detail that can be determined by the clinician. These data can lay the foundation for comprehensive risk stratification analyses. A minimum database set is also presented that will allow for data sharing that would lend itself to basic interpretation of trends. Outcome tables relating diagnoses, procedures, and various risk factors are presented.

Impact of retrograde cerebral perfusion on aortic arch aneurysm repair

OBJECTIVE

Protection of the brain is a primary concern in aortic arch surgery. Retrograde cerebral perfusion is a relatively new technique used for cerebral protection during profound hypothermic circulatory arrest. This study was designed to compare, retrospectively, the outcome of 109 patients undergoing aortic arch operation with and without the use of retrograde cerebral perfusion.

METHODS

Fifty-five patients had profound hypothermic circulatory arrest alone, and 54 patients had supplemental cerebral protection with retrograde cerebral perfusion. Mean age was 61 +/- 13 years and 58 +/- 14 years, respectively (mean +/- standard deviation). Twenty-two preoperative and intraoperative characteristics, including age, sex, acuity, presence of aortic dissection, and aneurysm rupture, were similar in the 2 groups (P >.05).

RESULTS

Mean circulatory arrest times (in minutes) were 30 +/- 19 in the group without retrograde cerebral perfusion and 33 +/- 19 in the group with retrograde cerebral perfusion, respectively. chi(2) Analysis revealed that patients operated on with the use of retrograde cerebral perfusion had significantly lower hospital mortality (15% vs 31%; P =.04) and in-hospital permanent neurologic complications (9% vs 27%; P =.01). Retrograde cerebral perfusion failed to reduce the prevalence of temporary neurologic dysfunction (17% vs 18%; P =.9). Stepwise multiple logistic regression revealed that extracorporeal circulation time, age, and lack of retrograde cerebral perfusion were statistically significant independent risk factors for hospital mortality. The same analysis revealed that lack of retrograde cerebral perfusion was the only significant independent risk factor for permanent neurologic dysfunction.

CONCLUSION

Retrograde cerebral perfusion decreased the prevalence of permanent neurologic complications and the hospital mortality in patients undergoing aortic arch operations.

Experience with antegrade bihemispheric cerebral perfusion in aortic arch operations

BACKGROUND

Various techniques have been used for cerebral protection in aortic arch operations. Antegrade cerebral perfusion has lost its popularity to hypothermic circulatory arrest to overcome the so-called cluttered operative field. Hypothermic circulatory arrest has its own problems of coagulopathy, time constraints, and prolongation of cardiopulmonary bypass time.

METHODS

Since June 1986 we have used antegrade bihemispheric cerebral perfusion with moderate hypothermia in 20 patients with aortic arch disease. Twelve patients had aneurysm, 7 had dissection, and 1 had traumatic tear. Five patients had had previous sternotomy for ascending aortic replacement. In addition to arch reconstruction, 7 patients had aortic valve replacement or repair, 2 patients had Bentall procedure, and 3 had selective innominate reconstruction. The mean cerebral perfusion time was 51+/-29 minutes. In 7 patients the cerebral perfusion time was between 60 and 120 minutes.

RESULTS

There was no in-hospital or 30-day mortality. The blood product requirements were significantly less with moderate hypothermia. One patient suffered cerebrovascular accident (5%). None of the 7 patients with cerebral perfusion times of 60 to 120 minutes had any neurologic deficits. These results are superior to those reported for hypothermic circulatory arrest with or without retrograde cerebral perfusion.

CONCLUSIONS

Antegrade bihemispheric cerebral perfusion is an optimal adjunct for cerebral protection during aortic arch operations.

Surgical treatment of aortic arch aneurysms in profound hypothermia and circulatory arrest

BACKGROUND

This study was undertaken to define the factors that influence mortality rate and neurologic outcome after repair of the aortic arch and various portions of the thoracic aorta in patients with profound hypothermia and circulatory arrest.

METHODS

Between November 1986 and January 1996, 105 patients were treated surgically for aortic disease involving the transverse aortic arch. Profound hypothermic circulatory arrest and selective brachiocephalic perfusion was used in all patients. In 19 patients retrograde cerebral perfusion was instituted during the period of circulatory arrest. Independent predictors for 30-day mortality and permanent neurologic deficits were evaluated by multiple logistic regression.

RESULTS

Thirty-day mortality for the entire group was 19% (20/105); 21.2% for urgent versus 15.4% for elective cases, respectively. Statistical analysis showed that age is the most important factor that significantly influences mortality rate (p < 0.0145) and neurologic outcome (p < 0.006). Variables such as circulatory arrest time (p < 0.24), previous cardiac or aortic operations (p < 0.19), and sex (p < 0.55) failed to show any influence on mortality rate. Permanent neurologic deficits were diagnosed in 12.9% (11/85) of the patients.

CONCLUSIONS

The incidence of permanent neurologic dysfunction as well as the mortality rate are predominantly related to the age of the patient. In this patient group, statistical analysis failed to show a direct correlation between duration of circulatory interruption and neurologic outcome.

Profound systemic hypothermia inhibits the release of neurotransmitter amino acids in spinal cord ischemia

Profound hypothermia induced with cardiopulmonary bypass has a protective effect on spinal cord function during operations on the thoracoabdominal aorta. The mechanism of this protection remains unknown. It has been proposed that the release of excitatory amino acids in the extracellular space plays a causal role in irreversible neuronal damage. We investigated the changes in extracellular neurotransmitter amino acid concentrations with the use of in vivo microdialysis in a swine model of spinal cord ischemia. All animals underwent left thoracotomy and right atrium-femoral artery cardiopulmonary bypass with additional aortic arch perfusion. Lumbar laminectomies were then done and microdialysis probes were inserted stereotactically in the anterior horn of the second and fourth segments of the lumbar spinal cord. The probes were perfused with artificial cerebrospinal fluid at a rate of 2 microliters/min and 15-minute samples were assayed by high-performance liquid chromatography. Group 1 animals (n = 6) underwent aortic clamping distal to the left subclavian artery and proximal to the renal arteries for 60 minutes at normothermia (37 degrees C) and group 2 animals (n = 5) were cooled to a rectal temperature of 20 degrees C before application of aortic clamps, maintained at this level during cardiopulmonary bypass until the aorta was unclamped, and then slowly rewarmed to 37 degrees C. Seven amino acids were studied, including two excitatory neurotransmitters (glutamate and aspartate) and five putative inhibitory neurotransmitters (glycine, gamma-aminobutyric acid, serine, adenosine, and taurine). Glutamate exhibited a threefold increase in extracellular concentration during normothermic ischemia compared with baseline values and remained elevated until 60 minutes after reperfusion. The increase in aspartate concentration was not significant. The extracellular concentrations of glycine and gamma-aminobutyric acid also increased significantly during ischemia and reperfusion. Hypothermia uniformly prevented the release of amino acids in the extracellular space. Glutamate levels remained significantly decreased even after rewarming to normothermia whereas glycine levels returned to baseline values. These results are consistent with a role for excitatory amino acids in the production of ischemic spinal cord injury and suggest that the mechanism of hypothermic protection may be related to decreased release of these amino acids in the ischemic spinal cord.

Subtypes of acute aortic dissection

The technique of open distal anastomosis using deep hypothermic circulatory arrest was used in 69 cases of acute type A aortic dissection. These cases were subcategorized by site of intimal tear, which was found in the ascending aorta in 41 patients (60%), in the arch in 22 patients (32%), and in the descending aorta in 5 patients (7%). Clinical characteristics and complications are described for these subtypes. Hospital mortality, which was 14.5% overall for acute type A dissections, was 14.6% for ascending tears, 18.2% for arch tears, and 0% for descending aortic tears. Six-year survival was 69% +/- 15% for ascending tears, 69% +/- 22% for arch tears, and 80% +/- 25% for descending tears (mean +/- SEM, p = NS). A classification system for aortic dissection is proposed, based on both site of origin and propagation.

Hypothermic circulatory arrest and other methods of cerebral protection during operations on the thoracic aorta

Current surgical techniques in operations on the thoracic aorta frequently require exclusion of the cerebral circulation for varying periods. During these periods, hypothermic circulatory arrest (HCA), selective cerebral perfusion (SCP), and retrograde cerebral perfusion (RCP) can be used for cerebral protection. Hypothermia is the principle component of these methods of protection. The main protective effect of hypothermia is based on reduction of cerebral energy expenditures and largely depends on adequate suppression of cerebral function. It is most effective at deep hypothermic levels (13 degrees C to 15 degrees C). Measures that preserve autoregulation of cerebral blood flow help increase the margin of safety with all methods of protection. There is solid experimental and clinical data indicating the safe limits and outcome following HCA. Current applications of SCP and RCP are fairly recent developments and do not have comparable supporting data. SCP can be used without deep hypothermia and allows prolonged periods of cerebral protection, but is complex in application. RCP is simpler, but always requires deep hypothermia. Present clinical data do not allow separation of its protective effect from that of HCA alone. Recent modifications in the application of HCA include monitoring of cerebral O2 extraction, and selective use of supplemental SCP to limit arrest times to less than 50 minutes, or RCP to prevent embolic strokes, as indicated. These changes appear to have reduced the overall mortality, the severity of embolic strokes, and stroke-related mortality.

Aortic arch aneurysm repair using selective cerebral perfusion

Seventy-seven patients underwent aortic arch aneurysm repair using selective cerebral perfusion from January 1987 to August 1992. Early and long-term results and preoperative and postoperative cerebral function were evaluated. Cerebral function was assessed by the mini mental state-Himeji test and the Wechsler adult intelligence scale. Thirty-six patients had true aneurysms, and 41 had dissection. Hospital mortality for true and dissecting aneurysms was 19.4% and 7.3%, respectively. The 5-year actuarial survival rates for true and dissecting aneurysms were 59.0% and 65.3%, respectively (not significant). There were no significant differences in test scores before or after operation. Repair or replacement of the aortic arch using selective cerebral perfusion is a safe procedure with acceptable hospital mortality.

Significance of distal false lumen after type A dissection repair

Fifty-eight patients underwent repair of acute type A dissection between 1986 and 1992. Follow-up aortogram, computed tomographic scan with contrast, magnetic resonance imaging scan, or a combination of these tests was available in 38 patients with preoperatively patent distal false lumens. All distal anastomoses were constructed with the open technique during a period of circulatory arrest. There were 25 suture and 13 intraluminal graft anastomoses. Patency of the distal false lumen was found in 47.3%. Use of the intraluminal graft for the distal anastomosis decreased patency, although not significantly (4/13, 30% versus 14/25, 56%; p = 0.14). The direction of flow into the false lumen was antegrade in 11 of 24 (45.8%) of sutured anastomoses and 0 of 9 intraluminal graft anastomoses (p < 0.01). Actuarial survival at 5 years for patients with closed distal false lumen was 95% +/- 4.8% versus 76% +/- 15% for patients with patency of the distal false lumen (p = not significant). Event-free survival at 5 years for both groups was 84% +/- 8.3% (closed false lumen) and 63% +/- 13.5% (patency of distal false lumen; p = not significant). This experience indicates that in the treatment of acute type A dissections, operative strategy and anastomotic technique play a role in reducing the incidence of patency and related complications of the distal false lumen.

Cerebral consequences of hypothermic circulatory arrest in adults

Despite widespread use of hypothermic circulatory arrest (HCA) in aneurysm surgery and for repair of congenital heart defects, there is continued concern about possible adverse cerebral sequelae. The search for ways to improve implementation of HCA has inspired retrospective clinical studies to try to identify risk factors for cerebral injury, and clinical and laboratory investigations to explore the physiology of HCA. At present, risk factors associated with less favorable cerebral outcome after HCA include: prolonged duration of HCA (usually greater than 60 min); advanced patient age; rapid cooling (less than 20 min); hyperglycemia either before HCA or during reperfusion; preoperative cyanosis or lack of adequate hemodilution; evidence of increased oxygen extraction before HCA or during reperfusion; and delayed reappearance of electroencephalogram (EEG) or marked EEG abnormality. Strategies advocated to increase safety of HCA include: pretreatment with barbiturates and steroids; use of alpha-stat pH regulation during cooling and rewarming; intraoperative monitoring of EEG; slow and adequate cooling, including packing of the head in ice; monitoring of jugular venous oxygen content; hemodilution; and avoidance of hyperglycemia. Current investigation focuses on delineating the relationship of cerebral blood flow (CBF) to cerebral oxygen consumption and glucose metabolism during cooling, HCA, rewarming, and later recovery, and identifying changes in acute intraoperative parameters, including the presence of intracerebral enzymes in cerebral spinal fluid, with cerebral outcome as assessed by neurological evaluation, quantitative EEG, and postmortem histology. Clinically, intraoperative monitoring of EEG and measurement of CBF by tracer washout or Doppler flows are contributing to better understanding of the physiology of HCA, and in the laboratory, nuclear magnetic resonance (NMR) spectroscopy has provided valuable insights into the kinetics of intracerebral energy metabolism. Promising strategies for the future include investigation of other pharmacological agents to increase cerebral protection, and use of "cerebroplegia" or intermittent perfusion between intervals of HCA to improve cerebral tolerance for longer durations of HCA.

Hypothermic circulatory arrest in the treatment of thoracic aortic lesions

The use of hypothermic circulatory arrest has been established in the treatment of aortic arch lesions. We recently used this method of arrest in the treatment of 10 consecutive patients with thoracic aortic lesions. Seven of these patients had dissecting aneurysms of the ascending aorta with extension into the aortic arch. One patient had a mycotic aneurysm of the arch, and 2 patients had arteriosclerotic aneurysms of the ascending aorta and entire aortic arch. All patients were supported and cooled with cardiopulmonary bypass. Circulatory arrest was maintained for periods of 21 to 63 minutes. All 10 patients survived the operative procedure. Nine patients remained intact neurologically. Renal function returned to baseline in all patients. Average blood replacement was 2.9 units. All patients have experienced an excellent surgical result. The average follow-up is 21.1 months. The technique facilitates a surgical approach to these lesions and appears to be the safest form of vital-organ preservation.

Hypothermia and circulatory arrest in reconstruction of aortic arch. A report of nine cases

From 1982 until October 1985 we operated 9 cases of aortic aneurysm involving the transverse aortic arch (5 male and 4 female, from 26 to 69 years). Two patients had an acute dissecting aortic aneurysm, the others had an aneurysm of the aortic arch involving also the ascending aorta in 5 cases and the descending aorta in 1. Three patients underwent aortic valve replacement and implantation of coronary orifices. Two patients had previously had AVR. The operation was carried out under cardiopulmonary by-pass. After obtaining 25 degrees C hypothermia the bypass was discontinued and the cerebral vessels were cannulated from inside of the opened aneurysm and perfused at a flow rate of 250 ml/min. The myocardium was protected by cold cardioplegia and topical cooling. During total circulatory arrest the distal aortic arch anastomoses were completed in 28-56 minutes. Then the by-pass was restarted and the rest of the operation was carried out as usual. One patient with an acute dissecting aortic aneurysm died on the 2 post-operative day due to brain damage and rupture of abdominal aorta. The other patients recovered well. There were no permanent neurological or myocardial complications. Three patients had a transient renal failure, one needing dialysis. The 8 survivors have done well 4-46 months after the operation.

Successful treatment of multiple simultaneous great vessel disruptions

Survival following ruptures of the thoracic aorta at sites other than the aortic isthmus is exceedingly rare. Herein we describe a successful outcome in a 62-year-old woman with ascending and isthmic aortic lacerations compounded by disruptions of the subclavian-innominate artery junction and the left vertebral-subclavian junction. Chest wall instability and a myocardial contusion further complicated her case.

The protective effect of profound hypothermia on the canine central nervous system during one hour of circulatory arrest

Circulatory arrest during profound hypothermia is a safe technique of cardiac surgery when used in selected instances. Despite its proven safety, the degree of cerebral protection offered by this technique is still poorly defined. Ten dogs anesthetized with Pentothal (thiopental sodium) were surface cooled to 32 degrees C. They were placed on cardiopulmonary bypass, cooled to 13 degrees C (cerebral temperature), and then underwent one hour of circulatory arrest. At the end of the arrest period, the dogs were rewarmed, resuscitated, and successfully weaned from bypass. A control group of 6 dogs were subjected to the same protocol but without the one-hour period of circulatory arrest. There were no group differences in animal weight, duration of surface cooling, cardiopulmonary bypass, or rewarming, mean flow, or mean arterial pressure. After a 7-day observation period, the dogs were killed with rapid tissue fixation using formalin. No neurological deficits were noted in any of the dogs during the observation period. The fixed brains were examined by a neuropathologist. No gross or microscopic evidence of cerebral hypoxia was seen in any of the animals. We conclude that one hour of circulatory arrest under profoundly hypothermic temperatures produces no detectable neurological changes or histological evidence of cerebral hypoxia.

Diagnostic and surgical management of patients with aneurysms of the thoracic aorta with various causes. Echocardiography and contrast enhanced computed tomography in prophylactic replacement of the ascending aorta

Sixty eight patients with aneurysms of the thoracic aorta were studied. Forty one had aortic dissection, 24 had dilatation only, and three had transverse aortic rupture. Sixteen had Marfan's syndrome; 17 had hypertension; and in eight there were other causal factors. In 17 the cause of the aneurysm was unknown. Histological examination did not help to establish the cause of aneurysm. Echocardiography failed to detect dissection of the ascending aorta in four (21%) out of 19 cases studied. The mortality rate in the whole series was 26%. Early (operative and hospital) and late deaths occurred in 20% and 6% of patients respectively. The early mortality rate was 40% in the 24 emergency cases of dissection of the ascending aorta, 9% in patients operated on for dilatation of the ascending and transverse aorta without dissection, and 8% in patients with chronic dissection of the ascending aorta who had elective operation. Early and late mortality rates were no higher in patients with Marfan's disease than in any of the other groups. It is suggested that contrast enhanced computer tomography should be performed in all patients with pronounced aortic root dilatation and in patients with Marfan's disease with symptoms which suggest dissection, even if they have only slight aortic root dilatation. Preventive replacement of the ascending aorta should be considered in more patients to reduce the number of emergency operations, in which the mortality rate is high. There is no definite limit of aortic root dilatation above which preventive replacement of the ascending aorta should be routinely considered.

Hypothermic circulatory arrest for cardiovascular lesions: technical considerations and results

During a six-year period (1979 to 1984), the technique of hypothermic circulatory arrest was used to operate on 128 patients. Our technique included induction of hypothermia (20 degrees to 24 degrees C) by femoral artery cannulation for return of oxygenated blood, "open" aortic reconstruction, and brief periods of circulatory arrest (range, 5 to 31 minutes; mean, 13 minutes). Eighty patients had dissecting aneurysms of the ascending aorta (42 acute, 38 chronic), 28 had fusiform aortic arch aneurysms, and 13 had annulo-aortic ectasia. Seven had other procedures. Ages ranged from 14 to 79 years (mean, 54 years). Of the 113 patients (88%) who survived the operation and were discharged, 107 are currently alive and well. Only 15 of the 21 deaths occurred within 30 days of operation, and 5 (33%) were in severely hypotensive patients whose operations were begun during active resuscitation. Of the 80 patients admitted with ascending aortic or arch dissection, an in-hospital mortality of 7.5% was achieved. A marked reduction was observed in such complications as postoperative hemorrhage, renal failure, and pulmonary insufficiency with our current hypothermic perfusion methods. Moreover, none of the five neurological complications could be attributed to anoxic cerebral injury during the period of circulatory arrest. This experience indicates that moderate levels of hypothermia provide adequate cerebral protection for most cardiovascular procedures, and our results encourage continued use of this method.

Management of aortic arch aneurysm using profound hypothermia and circulatory arrest

The cases of 9 patients with aneurysms involving the aortic arch, repaired under profound hypothermia (average, 15.5 degrees C) and circulatory arrest, are presented. Five patients underwent elective operation and 4, emergency operation. Arch resection and graft replacement were done in 7 patients. Two patients with infected pseudoaneurysms of the aortic arch received patch grafts. There were 2 deaths (22%) from coagulopathy and decerebration. Seven patients are alive and well 18 to 45 months following repair. The combination of profound hypothermia and circulatory arrest appears to be a promising solution to a difficult problem.

Brain Stem Auditory Evoked Potential Monitoring during Profound Hypothermia and Circulatory Arrest

The effects of decreased temperature on brain stem auditory evoked potentials (BAEP) have been previously described in mild to moderate hypothermia. This report describes BAEP monitoring during profound hypothermia (11°C) and circulatory arrest for repair of an aortic arch aneurysm. Recordings of BAEP were interpretable during cooling to 14°C, and demonstrated increasing interpeak (I-V) latency compatible with prolongation of brain stem conduction time. The changes rapidly returned to normal during rewarming from profound hypothermia, in a fashion similar to that seen after mild hypothermia, and therefore appear to be completely reversible.

Anaesthesia for aortic arch aneurysm repair: experience with 17 patients

Mortality and morbidity during aortic arch aneurysm repair is high despite improvements in surgical technique which attempt to assure brain protection during surgery. We successfully managed 17 patients using deep hypothermia and circulatory arrest. Anaesthesia consisted of pancuronium, fentanyl, plus isoflurane or halothane if needed. Pulmonary artery and arterial catheters were inserted. Surface cooling was performed followed by core cooling on cardiopulmonary bypass, using a heat exchanger. Total circulatory arrest was performed when esophageal temperature reached 12-14 degrees C after previous administration of thiopentone 30 mg X kg-1, methylprednisolone 2 gm, furosemide 40 mg and mannitol 25 gm. At that time the head was packed in ice and surgical correction performed. Mean arrest time was 36.5 +/- 13 minutes at a mean oesophageal temperature of 12.5 +/- 0.75 degrees C. No serious, permanent neurological deficit was found. Tracheostomy was required in five patients of whom two had chronic obstructive pulmonary disease (COPD). Two of these patients died of adult respiratory distress syndrome (ARDS) and renal failure. The reported technique is safe and can be easily used in patients undergoing aortic arch aneurysm repair.

Resection of aortic arch aneurysms: a comparison of hypothermic techniques in 60 patients

Hypothermic circulatory arrest has been used to facilitate resection of aneurysms of the aortic arch. During a five-year period, two methods of hypothermic arrest were compared in 60 patients. In Group 1, 20 patients underwent deep hypothermia (14 degrees to 18 degrees C) and circulatory arrest to allow repair of the transverse arch under optimal conditions. A hospital mortality of 50% occurred and was attributed to uncontrolled hemorrhage and cerebral or cardiac complications. In Group 2, modified techniques were employed in 40 patients and included moderate levels of hypothermia (22 degrees to 26 degrees C) and simplified operative methods, which reduced the duration of circulatory arrest and shortened the length of perfusion. Pretreatment of plasma-soaked Dacron grafts by autoclaving eliminated serious bleeding problems. A marked improvement in patient survival (90%) and reduction in postoperative complications were observed after adoption of these modifications. The improved results in the present series have reconfirmed our belief that this type of intervention is the preferred approach to aneurysms of the aortic arch.

Bypass grafting and aneurysmorrhaphy for aortic arch aneurysms

The technique of permanent aortic arch bypass grafting combined with simultaneous aneurysmorrhaphy, excision or exclusion of the aneurysm without the use of systemic heparinization, cardiopulmonary bypass, or external bypass shunting has been used successfully in treating 5 patients with aneurysms of the aortic arch. There were no complicating cerebral vascular accidents, bleeding diatheses, or signs of distal embolization. There were 2 deaths; 1 patient died early (10 days postoperatively) of myocardial infarction, and the other died over one year later of unrelated causes. Follow-up has extended to an interval of seven years. The early death subsequent to myocardial infarction in 1 patient prompted the routine use of preoperative carotid and coronary angiography for assessment of these systems. Severe occlusive disease in these vessels requires a staged or simultaneous reconstruction prior to management of the aortic aneurysm.

Annulo-aortic ectasia involving the aortic arch. Total replacement using a composite graft. A case report

A case of annulo-aortic ectasia involving the aortic arch and the proximal part of the left subclavian artery is reported. The aorta was replaced with a composite graft (Björk-shiley tilting disc valve and very soft Cooley low-porosity prosthesis) and the coronary ostia and the innominate and left common carotid arteries were implanted directly into the prosthetic tube. The patient recovered without complications.

Surgical treatment of aneurysms of the transverse aortic arch: experience with 25 patients using hypothermic techniques

Surgical treatment of aneurysms of the transverse aortic arch has been a challenge to cardiovascular surgeons. The problems include protection of the brain and spinal cord from ischemic or embolic injury, prevention of hemorrhage and coagulopathy, and prevention of myocardial damage during prolonged extracorporeal circulation. Two methods are described. Group 1 included 20 patients in whom deep hypothermic conditions were induced (12 degree to 16 degree C) followed by circulatory arrest and partial exsanguination. In this group a 50% hospital mortality occurred. Patients in Group 2 underwent moderate induced hypothermia (24 degree to 26 degree C) with continuous cerebral perfusion during the period of peripheral circulatory arrest. Four of 5 patients survived this technique, leading us to believe this method is preferred over the deeper levels of hypothermia. A method of preclotting the Dacron graft with platelet-rich plasma and autoclaving is described. It has eliminated interstitial bleeding through fabric grafts.

Transverse aortic arch aneurysm: improved results of treatment employing new modifications of aortic reconstruction and hypothermic cerebral circulatory arrest

The results of graft replacement for aneurysms involving the entire transverse aortic arch have lagged far behind that achieved for similar lesions located elsewhere. For example, prior to the study reported here, the mortality rate of the former, in our experience, was 25%, whereas it was only 8% for the most extensive forms of thoracoabdominal aortic aneurysms. The difference had been due to limitations and complications of methods employed for cerebral and myocardial protection. The high mortality rate in our patients was due to the deficiencies of temporary bypass graft and cardiopulmonary bypass, and separate brachiocephalic perfusion employed for this purpose. This report is concerned with the use of profound hypothermia for cerebral protection and the application of graft inclusion and direct brachiocephalic arterial reattachment to prevent bleeding in region of operation, as so successfully employed in patients with thoracoabdominal aortic aneurysms. The entire thoracic aorta was involved in four patients, the aortic valve in two patients, coronary artery bypass was performed in two patients, and the pulmonary artery was obstructed in one patient. Employing the techniques described in this report, all eight patients with these extensive lesions survived without complication.