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Notes: 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. (J Card Surg 1994;9:729–733)

Notes: Since the original description of composite replacement of the aortic valve and ascending aorta by Bentall in 1968, several modifications of the technique have been described. In order to evaluate the results of these different techniques, we have retrospectively reviewed our results with 140 consecutive patients who underwent Bentall operations between October 1986 and March 1994, using three different anastomotic techniques: Classic, n = 30; Button, n = 95, and Cabrol, n = 15. Overall hospital mortality was 5%. In univariate analysis, acute type A dissection, rupture, new preoperative neurological symptoms, and the Cabrol technique were associated with a higher hospital mortality, but by multivariate analysis no independent risk factors were demonstrated. Overall rates of reoperation did not differ among the three techniques (Classic 4.1%/pt-yr, Button 2.7%/pt-yr, Cabrol 0%/pt-yr; p = 0.44). The actuarial freedom from reoperation was 87% at 5 years. The 5-year actuarial survival for all patients was 79% (Classic 85%, Button 82%, Cabroi 52%): the poorer results with the Cabroi modification are likely due to patient selection, complicated by a higher early mortality in this small group of patients. The presence of dissection was associated with a higher mortality in Marfan patients (50% vs 8%, p = 0.03). The rate of aortic valve-related complications was 3.6%/pt per year. Actuarial event-free survival was 67% at 5 years. Current indications for an elective Bentall procedure include an ascending aortic diameter of 6 cm or greater, with significant aortic valvular dysfunction, and dilatation of the ascending aorta greater than 5 cm in patients with Marfan syndrome or a bicuspid aortic valve. The routine procedure of choice is the Button Bentall techniaue. with the Classic Bentall and the Cabrol variation reserved for use under special circumstances. (J Card Surg 1994;9:466–481)

Notes: 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°C to 15°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. (J Card Surg 1994;9:525–537)

Notes: Retrograde cerebral perfusion (RCP) is a new method of cerebral protection that has been touted as an improvement over hypothermic circulatory arrest (HCA). However, RCP has been used clinically for durations and at temperatures that are “safe” for HCA alone. This study was designed to compare RCP to HCA and antegrade cerebral perfusion (ACP) deliberately exceeding “safe” limits, in order to determine unequivocally whether RCP provides better cerebral protection than HCA. Four groups of six Yorkshire pigs (20 to 30 kg) were randomly assigned to undergo 90 minutes of RCP, ACP, HCA, or HCA with heads packed in ice (HCA-HP) at an esophageal temperature of 20°C. Arterial, mixed venous and cerebral venous oxygen, glucose and lactate contents; quantitative EEG; were monitored at baseline (37°C); at the end of cooling cardiopulmonary bypass (20°C); during rewarming (30°C); and at two and four hours post intervention. Animals were recovered and were evaluated daily using a quantitative behavioral score (0 to 9). Mean behavioral score was lower in the HCA group than in the other three groups at seven days (HCA 5.8 ± 1.1; RCP 8.5 ± 0.2; ACP 9.0 ± 0.0; HCA-HP 8.5 ± 0.2, p 〈 0.05). Recovery of QEEG was better in the ACP group than in all others, but the RCP group had faster EEG recovery than HCA alone, although not better than HCA-HP (HCA 15 ± 4; RCP 27 ± 3; ACP 78 ± 5; HCA-HP 19 ± 3, p 〈 0.001). However, histopathological evidence of ischemic injury was present in 5 of 6 HCA animals and also in 4 of 6 of the HCP-HP group, but only In 1 of 6 RCP animals and in none of the ACP group. This study demonstrates that ACP affords the best cerebral protection by all outcome measures, but RCP provides clear improvement compared to HCA. (J Card Surg 1994;9:560–575)

Notes: Abstract Background: Postoperative dissection in some patients is related to manipulation of the aorta and accounts for 3% to 5% of deaths after cardiac surgery. Methods: Between 1987 and 1999, 109 patients with previous cardiac operations were treated for chronic type A dissection. In 31 of the patients, the etiology was related to aortic manipulation. Twenty-one patients (17 men, 4 women; 67 ± 13 years of age) had isolated coronary artery bypass grafting (CABG) as their first operation and were reviewed. The interval between operations was 52.9 ± 47.3 months. Results: Reoperation was elective in 11 patients, urgent in 10 patients. Median maximal aortic diameter was 6.8 ± 2.1 cm; 9 patients had major aortic insufficiency. The intimal tear was at the partial occlusion clamp site in 12 patients (57.1%), at the cross-clamping site in 4 patients (19.1%), and at the proximal anastomosis in 1 patient (4.8%); 4 patients (19.1%) had multiple tears at several sites. Cystic media necrosis was present in 9.5% of the patients, severe atherosclerosis in 47.6% of the patients, and 42.9% of the patients had both. Nine patients (42.9%) underwent a modified Bentall procedure, 12 patients (57.1%) underwent a supracoronary anastomosis, and all had open distal anastomosis. There were two (9.5%) hospital deaths and three (14.3%) postoperative strokes. Freedom from cardiac or aorta-related mortality was 85.7% at a mean follow-up of 49.3 months. Conclusions: In patients who develop type A dissection of the aorta after previous CABG, the intimal tear most often is at partial occlusion clamp site. This complication is associated with morbidity and mortality. It remains to be seen whether the use of partial occlusion clamps on the pulsating and often diseased aorta during off-pump coronary artery bypass (OPCAB) will increase the risk of delayed iatrogenic dissections.

Notes: Recent work in our laboratory has demonstrated the effectiveness of somatosensory evoked potentials (SEPs) In identifying the critical intercostal arteries (CICAs) for preserving spinal cord integrity during simulated aortic aneurysm repairs in the pig. Further studies have also demonstrated increased preservation of neurological function during prolonged aortic clamping if ClCAs are perfused until ligation or clipping, as opposed to transaortic identification of back-bleeding intercostals and their subsequent ligation. We have developed a technique of repair of descending thoracic and thoracoabdominal aortic aneurysms and dissections that uses these principles. Since January 1993, 26 patients have undergone repair of their aortas using this new technique and SEP directed intercostal artery ablation. There were 22 (85%) long-term survivors among 10 thoracoabdominal and 16 descending aortic repairs. All patients with uncorrected abnormal SEP recordings developed paralysis; one patient who required reimplantatlon of an intercostal artery island into the aortic graft had normal neurological function postoperatively. Paraplegia was seen in only one of the surviving patients, but this patient had normal intra- and postoperative SEPs (4% false negative). Our experience suggests that SEP-guided obliteration of intercostal arteries while maintaining perfusion may be a useful approach to the surgical repair of descending and thoracoabdominal aortic disease. (J Card Surg 1994;9:662–672)

Notes: 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 〉 60 min); advanced patient age; rapid cooling (〈 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.