Aortic arch aneurysm repair using selective cerebral perfusion

Implications from neurologic assessment of brain protection for total arch replacement from a randomized trial

OBJECTIVE

The study objective was to perform a randomized trial of brain protection during total aortic arch replacement and identify the best way to assess brain injury.

METHODS

From June 2003 to January 2010, 121 evaluable patients were randomized to retrograde (n = 60) or antegrade (n = 61) brain perfusion during hypothermic circulatory arrest. We assessed the sensitivity of clinical neurologic evaluation, brain imaging, and neurocognitive testing performed preoperatively and 4 to 6 months postoperatively to detect brain injury.

RESULTS

A total of 29 patients (24%) experienced neurologic events. Clinical stroke was evident in 1 patient (0.8%), and visual changes were evident in 2 patients; all had brain imaging changes. A total of 14 of 95 patients (15%) undergoing both preoperative and postoperative brain imaging had evidence of new white or gray matter changes; 10 of the 14 patients had neurocognitive testing, but only 2 patients experienced decline. A total of 17 of 96 patients (18%) undergoing both preoperative and postoperative neurocognitive testing manifested declines of 2 or more reliable change indexes; of these 17, 11 had neither imaging changes nor clinical events. Thirty-day mortality was 0.8% (1/121), with no neurologic deaths and a similar prevalence of neurologic events after retrograde and antegrade brain perfusion (22/60, 37% and 15/61, 25%, respectively; P = .2).

CONCLUSIONS

Although this randomized clinical trial revealed similar neurologic outcomes after retrograde or antegrade brain perfusion for total aortic arch replacement, clinical examination for postprocedural neurologic events is insensitive, brain imaging detects more events, and neurocognitive testing detects even more. Future neurologic assessments for cardiovascular procedures should include not only clinical examination but also brain imaging studies, neurocognitive testing, and long-term assessment.

Deep hypothermic circulatory arrest

Effective cerebral protection remains the principle concern during aortic arch surgery. Hypothermic circulatory arrest (HCA) is entrenched as the primary neuroprotection mechanism since the 70s, as it slows injury-inducing pathways by limiting cerebral metabolism. However, increases in HCA duration has been associated with poorer neurological outcomes, necessitating the adjunctive use of antegrade (ACP) and retrograde cerebral perfusion (RCP). ACP has superseded RCP as the preferred perfusion strategy as it most closely mimic physiological perfusion, although there exists uncertainty regarding several technical details, such as unilateral versus bilateral perfusion, flow rate and temperature, perfusion site, undue trauma to head vessels, and risks of embolization. Nevertheless, we believe that the convenience, simplicity and effectiveness of straight DHCA justifies its use in the majority of elective and emergency cases. The following perspective offers a historical and clinical comparison of the DHCA with other techniques of cerebral protection.

What is the best method for brain protection in surgery of the aortic arch? Straight DHCA

Straight deep hypothermic circulatory arrest (DHCA) is a technique available for brain preservation during deep hypothermic arrest in aortic arch replacement. In this article, the author discusses the practice of straight DHCA in his institute and the advantage of this technique over other brain preservation techniques.

Trial of new vascular clips for aortic anastomosis in a canine model

OBJECTIVES

We created a new vascular clip designed for aortic surgery. The purposes of this investigation were to examine surgical applicability in a clinically relevant aortic replacement model and to assess biomechanical strength of the clipped anastomosis and serial histologic changes in the clipped anastomotic site.

METHODS

Twenty-one beagles underwent descending thoracic aortic replacement. Distal anastomosis was performed with the new clips, mimicking the cuffed anastomosis technique, and proximal anastomosis was carried out by conventional suture anastomosis. Tissue specimens of the anastomotic sites were harvested at 1, 3, 6, and 12 months postoperatively for examination.

RESULTS

There was no significant difference in the time required to carry out clip anastomosis (12.2 +/- 1.3 minutes) and suture anastomosis (13.7 +/- 0.9 minutes; P = .38). Neither type of anastomotic site was disrupted by raising the intraluminal pressure to 280 mm Hg. Microscopically, the areas of aortic wall compressed by vascular clips appeared as hyalinized areas adjacent to surrounding collagen fibers, with no significant infiltration of inflammatory cells. Identical histologic changes were observed at the site of the sutured anastomosis. The media at the clipped anastomosis site was significantly thinner than that at the sutured anastomosis site at 1 month after the operation. However, there was no significant difference in the thickness of the media at 3 months.

CONCLUSIONS

The new vascular clips were effective in this clinically relevant model, with appropriate biomechanical strength, and the anastomotic sites underwent similar histologic changes to those observed after suture anastomosis.

Straight deep hypothermic arrest: experience in 394 patients supports its effectiveness as a sole means of brain preservation

BACKGROUND

The three methods of brain preservation for aortic arch surgery--straight deep hypothermic circulatory arrest (DHCA) without perfusion adjuncts, retrograde cerebral perfusion, and antegrade cerebral perfusion--remain controversial. Patients in this report underwent surgery solely with DHCA.

METHODS

Straight DHCA at 19 degrees C was used in 394 patients (267 males, 127 females) during a 10-year period. Mean age was 61.3 years (range, 15 to 88 years). Eighty-seven cases (22.1%) were urgent or emergencies. Thirty-eight (9.6%) were performed for descending or thoracoabdominal pathology and the rest for ascending/arch (102 hemiarch, 49 total arch). Ninety-one patients (23.1%) had dissections. The head was packed in ice. No barbiturate coma was used.

RESULTS

DHCA lasted a mean of 31.0 minutes (range, 10 to 66 minutes). Reexploration for bleeding was required in 4.5% (18/394). Overall mortality was 6.3% (25/394). Mortality was 3.6% (11/307) for elective cases and 16% (14/87) for emergency cases. The stroke rate was 4.8% (19/394). The seizure rate was 3.1% (12/394). Forty-five patients with high professional cognitive demands (MD, PhD, attorney, etc) performed without detriment postoperatively. Among patients with DHCA exceeding 40 minutes, the stroke rate was 13.1% (8/61); a neuroradiologist's review of brain computed tomography scans found 62.5% of these strokes (5/8) to be embolic and 37.5% (3/8) hypoperfusion related. By multivariable logistic regression, emergency operation and descending location increased morbidity and mortality.

CONCLUSIONS

Straight DHCA without adjunctive perfusion suffices as a sole means of cerebral protection. Stroke and seizure rates are low. Cognitive function, by clinical assessment, is excellent. Especially for straightforward ascending/arch reconstructions, there is little need for the added complexity of brain perfusion strategies.

Surgical treatment of thoracic aortic aneurysm in patients with concomitant coronary artery disease

OBJECTIVE

Surgical treatment of thoracic aortic surgery in patients with coronary artery disease was investigated.

METHODS

Between 1990 and April 2003, 330 patients underwent elective thoracic aortic surgery. Fifty-six patients who underwent aortic root reconstruction were excluded and 274 patients were examined. Fifty-four (20%) patients showed concomitant coronary artery disease. Ten had undergone coronary revascularization previously; and 3 underwent coronary revascularization [2 coronary artery bypass grafting (CABG), 1 percutaneous transluminal coronary angioplasty (PTCA)] before aortic surgery. Twenty-three patients underwent elective CABG simultaneously and 2 patients had additional coronary artery bypass because of cardiac ischemia during operation. The number of patients who underwent thoracic aortic surgery including Asc Ao+AVR was 2, hemi arch 1, total arch 15, distal arch 5, distal arch+LV aneurysmectomy 1, and thoracoabdominal Ao 1. Two patients underwent coronary revascularization with arterial grafts and the others with SVG grafts.

RESULTS

There was one hospital death (4%). In patients without coronary bypass, 2 patients suffered cardiac ischemic events.

CONCLUSION

Our thoracic aortic operations with concomitant CABG using SVG were overall successful. Our current strategies for thoracic aortic surgery in patients with concomitant coronary artery disease include conducting a dipyridamole myocardial perfusion-imaging test first in patients not at risk of coronary artery disease, and if the test is positive, coronary angiography is performed and aggressive coronary revascularization is conducted where possible.

Quality of life in elderly patients following thoracic aortic surgery

OBJECTIVE

While early outcomes following thoracic aortic surgery are improving, the long-term quality of life in elderly patients following this procedure remains uncharacterized. Thus, the goal of this retrospective study was to investigate quality of life in elderly patients following thoracic aortic surgery in regard to age, urgency of operation, operative procedures, skin incision, selective cerebral perfusion (SCP) time, and cardiopulmonary bypass time.

METHODS

One hundred-and-eleven surviving patients that underwent thoracic aortic surgery between 1987 and 1999 were enrolled in this study. The Short Form-36 (SF-36) health questionnaire was administered to all participants.

RESULTS

Some measures of quality of life were lower in those patients that underwent the procedure as compared to age- and gender-matched normal population. Quality of life (QOL) of the elderly patients with prolonged SCP time (>120 minutes) was significantly lower in the dimension of role-physical of SF-36. On the other hand, there was no significant difference between the subgroups in terms of urgency of operation, operative procedure, skin incision, and cardiopulmonary bypass time.

CONCLUSIONS

Physical and mental quality of life was significantly lower in elderly patients undergoing thoracic aortic surgery. Prolonged SCP time (>120 minutes) was a negative factor for long-term QOL. We advocate discussing the data with patients when obtaining informed consent for this procedure.

Use of cuffed anastomosis in total aortic arch replacement

The distal aortic anastomosis portion of the total arch surgery remains technically complex especially in cases in which an aortic arch aneurysm extends below level of carina. We present the cuffed anastomosis that overcomes this difficulty. We applied this technique in 49 patients of elective total aortic arch aneurysm repair using selective cerebral perfusion from 1996 to 2001. Hospital mortality was 2%.

Neurological Complications of Aortic Surgery

Surgery of the aortic arch involves an inherently high risk of neurological complications. A number of factors have been identified which may predispose the patient to brain injury, and various techniques employed in an attempt to counteract these are outlined. In particular the vulnerability of the brain to ischemia has led to the development of three adjunctive cerebral protective techniques, hypothermic circulatory arrest, retrograde cerebral perfusion and selective antegrade cerebral perfusion, all based upon brain cooling and metabolic inhibition. The relative merits and disadvantages of these techniques are therefore discussed. Finally, pharmacologic adjuncts and potential future developments in aortic arch surgery are discussed.

Prospective comparative study of brain protection in total aortic arch replacement: deep hypothermic circulatory arrest with retrograde cerebral perfusion or selective antegrade cerebral perfusion

BACKGROUND

The purpose of this study was to compare the results of total aortic arch replacement using two different methods of brain protection, particularly with respect to neurologic outcome.

METHODS

From June 1997, 60 consecutive patients who underwent total arch replacement through a midsternotomy were alternately allocated to one of two methods of brain protection: deep hypothermic circulatory arrest with retrograde cerebral perfusion (RCP: 30 patients) or with selective antegrade cerebral perfusion (SCP: 30 patients). Preoperative and postoperative (3 weeks) brain CT scan, neurological examination, and cognitive function tests were performed. Serum 100b protein was assayed before and after the cardiopulmonary bypass, as well as 24 hours and 48 hours after the operation.

RESULTS

Hospital mortality occurred in 2 patients in the RCP group (6.6%) and 2 in the SCP group (6.6%). New strokes occurred in 1 (3.3%) of the RCP group and in 2 (6.6%) of the SCP group (p = 0.6). The incidence of transient brain dysfunction was significantly higher in the RCP group than in the SCP group (10, 33.3% vs 4, 13.3%, p = 0.05). Except in patients with strokes, S-100b values showed no significant differences in the two groups (RCP: SCP, prebypass 0.01+/-0.04: 0.05+/-0.16, postbypass 2.17+/-0.94: 1.97+/-1.00, 24 hours 0.61+/-0.36: 0.60+/-0.37, 48 hours 0.36+/-0.45: 0.46+/-0.40 microg/L, p = 0.7). There were no intergroup differences in the scores of memory decline (RCP 0.74+/-0.99; SCP 0.55+/-1.19, p = 0.6), orientation (RCP 1.11+/-1.29; SCP 0.50+/-0.76, p = 0.08), or intellectual function (RCP 1.21+/-1.27; SCP 1.05+/-1.15, p = 0.7).

CONCLUSIONS

Both methods of brain protection for patients undergoing total arch replacement resulted in acceptable levels of mortality and morbidity. However, the prevalence of transient brain dysfunction was significantly higher in patients with the RCP.

Concomitant replacement of the aortic root and aortic arch with or without secondary thoracoabdominal aorta replacement

OBJECTIVES

Extensive aortic replacement, such as concomitant aortic root and arch replacement, thoracoabdominal aortic repair, and complete thoracic aorta replacement, remains controversial. We studied surgical morbidity and mortality in patients undergoing concomitant aortic root and arch replacement, and those undergoing secondary replacement of the thoracoabdominal aorta after this preceding procedure.

SUBJECTS AND METHODS

Between January, 1987 and March 1999, 21 patients (mean age: 52 years) underwent concomitant aortic root and arch replacement involving 3 surgical procedures--aortic root replacement with composite graft and arch (n = 12), aortic root replacement with valve sparing and arch (n = 4), or aortic root replacement with composite graft and arch and elephant trunk (n = 5).

RESULTS

Overall hospital mortality was 4.8%. Six patients (mean age: 42 years) underwent secondary thoracoabdominal aorta replacement after the concomitant root and arch procedure. The mean time until secondary surgery was 9.5 months. There was 1 hospital death.

CONCLUSION

Concomitant replacement of the aortic root and arch, or secondary replacement of the thoracoabdominal aorta after concomitant root and arch replacement can be conducted with low surgical morbidity and mortality.

Spontaneous rupture of the thoracic aorta

BACKGROUND

Spontaneous rupture of the thoracic aorta without trauma, aneurysm, or dissection is an extremely rare but catastrophic disorder. Two cases of spontaneous aortic rupture are presented, both treated surgically with satisfactory results.

METHODS

A review of the English literature found 16 patients with the diagnosis of spontaneous rupture of the thoracic aorta from 1961 through 1998. Eighteen reported cases, including the 2 cases presented herein, are reviewed.

RESULTS

The representative clinical picture is one of a middle-aged hypertensive patient with acute chest pain and collapse, with imaging modalities demonstrating hemopericardium, hemomediastinum, or hemothorax. According to the reported experiences, aortography was accurate for identifying the rupture site although the findings were sometimes subtle. Misdiagnosis or nonsurgical management resulted in the patient's death. All 8 patients who did not undergo aortic repair died within 3 weeks after the onset, whereas 9 of 10 patients who underwent surgical aortic repair survived.

CONCLUSIONS

For patients with a definitive or possible diagnosis of spontaneous rupture of the thoracic aorta, prompt operation is imperative through an optimal surgical approach to identify and repair the rupture site with appropriate circulatory support.

Surgical management of atherosclerotic aortic arch aneurysms using selective cerebral perfusion: 7-year experience in 52 patients

OBJECTIVE

Patients with atherosclerotic aortic arch aneurysms are at greater risk for brain complication. We report our techniques and results of operation using selective cerebral perfusion.

METHODS

We retrospectively analyzed 52 consecutive patients with atherosclerotic aortic arch aneurysms (mean age, 70 years, range, 53-86 years), who underwent operation between April 1992 and March 1999. The operation was non-elective in 11 patients (21.1%). Concomitant operations included eight coronary artery bypass grafting and one aortic valve replacement. Simultaneous distal aortic reconstruction was performed in three patients. The operation was performed through median sternotomy. To avoid brain embolism, total arch replacement with a branched prosthesis was performed in 48 patients, in an attempt to exclude affected segments of aorta. In addition, retrograde femoral artery perfusion was avoided and cerebral circulation was isolated before aortic manipulation. To achieve even blood flow distribution, we employed perfusion and continuous pressure monitoring of all the three arch vessels. The perfusion rate was 12+/-2 ml/kg per min and the pressure was kept around 50 mmHg. Deep hypothermic arrest of the lower torso (bladder temperature, 22 degrees C) was used during open distal aortic anastomosis.

RESULTS

The hospital mortality rate was 11.5% (six of 52), and 7.3% (three of 41) for elective cases. Only one patient (1. 9%) developed permanent focal neurological deficit. Six other patients showed temporary brain complications, which was global (delirium) in three and focal in three others.

CONCLUSIONS

Selective cerebral perfusion is a safe brain protection method, and our strategy seems effective for embolic stroke prevention.

Predictive factors for mortality and cerebral complications in arteriosclerotic aneurysm of the aortic arch

BACKGROUND

The incidence of cerebral complications is high in patients with aortic arch aneurysm.

METHODS

Between December 1977 and December 1995, 246 patients with arteriosclerotic arch aneurysm underwent operation. Thirty-nine patients had an aneurysm involving the entire arch, 193 had only distal arch aneurysm, and 14 had arch aneurysm extending to the descending aorta. Eighty-seven patients underwent replacement of the total arch, 85 had replacement of only the distal arch, 14 had simultaneous replacement of the descending aorta, 45 had patch repair, and 15 had thromboexclusion. Selective cerebral perfusion was used in 112 patients and partial bypass in 58 in the earlier series of patients, but deep hypothermic circulatory arrest with retrograde cerebral perfusion technique was exclusively applied in the most recent 76 patients.

RESULTS

There were 50 (20%) early deaths and 37 (19%) late deaths. Postoperative stroke was found in 26 (11%) patients of which 13 (50%) died. Mutual predictive factors for postoperative mortality and stroke were earlier series, preoperative chronic renal failure, ruptured aneurysm, arch clamping during procedure, and using partial cardiopulmonary bypass. Among 129 patients operated on during the most recent 5 years, early mortality and incidence of stroke decreased to 14.7% and 6.9%, respectively.

CONCLUSIONS

Results of operations for arteriosclerotic aneurysms of the transverse aortic arch in 246 patients during a period of 17 years have been improving but are still not satisfactory.

Brain damage after aortic arch repair using selective cerebral perfusion

BACKGROUND

Selective cerebral perfusion is one of the most popular methods for cerebral protection during aortic arch repair. However, causes of postoperative brain damage are not fully understood. We analyzed brain damage after aortic arch repair using selective cerebral perfusion for true aortic arch aneurysm in regard to preoperative cerebral infarction and intracranial and extracranial occlusive arterial disease.

METHODS

Over a 9-year period, 60 patients with true aortic arch aneurysm underwent aortic arch repair using selective cerebral perfusion. Postoperative brain damage was evaluated in regard to preoperative cerebral infarction detected by computed tomography, magnetic resonance imaging, or both in 50 patients and intracranial and extracranial occlusive arterial disease detected by digital subtraction angiography, magnetic resonance angiography, or both in 35 patients.

RESULTS

Seven (12%) of the 60 patients died within 30 days of operation. Postoperative brain damage occurred in 6 (10.5%) (3, coma, and 3, hemiplegia) of 57 patients; 3 patients who died without awakening were excluded. Preoperatively, old cerebral infarction was detected in 9 patients (18%), and silent cerebral infarction (lacunar infarction and leukoaraiosis) was diagnosed in 26 patients (52%). Postoperative brain damage occurred in 3 (33%) of the 9 patients with preoperative cerebral infarction and in 3 (23%) of 13 patients with negative preoperative brain findings; this excludes 2 patients who died without awakening. No patient with silent cerebral infarction had postoperative brain damage. Occlusive arterial disease was detected in 7 patients (20%). The incidence of brain damage in these patients was 71% (5/7), which was significantly greater than that of 4% (1/28) in patients without occlusive arterial disease (p < 0.001).

CONCLUSIONS

Silent cerebral infarction may not be a risk factor for postoperative brain damage. Preoperative evaluation of intracranial and extracranial occlusive arterial disease provides important information as to whether a patient might sustain brain damage after aortic arch repair using selective cerebral perfusion.

[Open distal anastomosis or aortic balloon occlusion technique during complete aortic arch replacement]

The technique of open distal anastomosis or application of aortic balloon occlusion catheter designed to occlude the descending thoracic aorta have been used in 33 and 19 patients, respectively, to control bleeding during the procedure of distal anastomosis for complete aortic arch replacement with a prosthetic graft. These two techniques allowed us a simple approach to the lesion and the avoidance of clamp injury to the fragile aortic tissue. Open distal anastomosis was applied for 91% patients of operated aortic dissection and all emergent cases, it's duration ranged from 10 to 110 minutes with an average of 58 minutes under 18.2 degrees C of lowest esophageal temperature. On the other hand, aortic occlusion balloon was inserted for mainly true aortic aneurysm patients without an emergency, and helped to maintain the perfusion pressure on a lower part of body around 50 mmHg by the 1550 ml/min in an average of perfusion flow femoral artery under 21.2 degrees C of temperature. The difference of postoperative renal and liver function evaluated by serum enzyme levels of total bilirubin, GOT, GPT, LDH, creatinine and BUN did not reach to statistical significance between the patients using open distal anastomosis and balloon occlusion, however, the incidence of postoperative complication including either renal, liver dysfunction, abdominal problem or paraplegia was significantly higher in the patient group with open distal technique. Either open distal anastomosis or aortic balloon occlusion technique would be appropriately selected according to the patient's characteristics or the condition of aortic disease to be operated.

Aortic arch operation using selective cerebral perfusion for nondissecting thoracic aneurysm

BACKGROUND

Risks of increasing mortality and disability in aortic arch operations using the selective cerebral perfusion method for nondissecting aneurysm have not yet been determined. A multicenter, retrospective study was employed.

METHODS

The subjects were 143 patients who were admitted to one of the nine cardiovascular centers between January 1988 and December 1993, including 15 with ruptured aneurysm. A graft replacement of the transverse aortic arch or distal arch was performed in 80 patients, extensive aortic reconstruction comprising simultaneous replacement of the ascending or descending thoracic aorta (or both) in 46, and patch repair of involved arch in 17. The mean postoperative follow-up period was 19 months.

RESULTS

Hospital mortality was 36/143 patients (25.2%). Univariate analysis revealed that age of 70 years or more, ruptured aneurysm, and renal dysfunction affected hospital mortality. Neurologic deficits were noted in 15 patients (10.5%). Reoperation was performed in 13 patients for residual distal aneurysm or false aneurysm. Late death occurred in 10 patients and were due to vascular complications in 6. Multivariate analysis confirmed that aneurysmal rupture and renal dysfunction were independent predictors for vascular death including hospital mortality.

CONCLUSIONS

The present study confirmed that age, aneurysmal rupture, and renal dysfunction were significant predictors for mortality and disability in the aortic arch operation using selective cerebral perfusion for nondissecting thoracic aneurysm.

Cerebral protection during moderate hypothermic circulatory arrest: histopathology and magnetic resonance spectroscopy of brain energetics and intracellular pH in pigs

OBJECTIVE

We evaluated the effect of antegrade and retrograde brain perfusion during moderate hypothermic circulatory arrest at 28 degrees C.

METHODS

Phosphorus 31-magnetic resonance spectroscopy was used to follow brain energy metabolites and intracellular pH in pigs during 2 hours of ischemia and 1 hour of reperfusion. Histopathologic analysis of brain tissue fixed at the end of the experimental protocol was performed. Fourteen pigs were divided into two experimental groups subjected to antegrade (n = 6) or retrograde (n = 8) brain perfusion. Anesthesia (n = 8) and hypothermic cardiopulmonary bypass groups (15 degrees C, n = 8) served as control subjects. In the antegrade and retrograde brain perfusion groups, the initial bypass flow rate was 60 to 100 ml x kg(-1) x min(-1). In the antegrade group, the brain was perfused through the carotid arteries at a flow rate of 180 to 210 ml x min(-1) during circulatory arrest at 28 degrees C. In the retrograde group, the brain was perfused through the superior vena cava at a flow rate of 300 to 500 ml x min(-1) during circulatory arrest at 28 degrees C.

RESULTS

The intracellular pH was 7.1 +/- 0.1 and 7.2 +/- 0.1 in the anesthesia and hypothermic bypass groups, respectively. Brain intracellular pH and high-energy metabolites (adenosine triphosphate, phosphocreatine) did not change during the course of the 3.5-hour study. In the antegrade group, adenosine triphosphate and intracellular pH were unchanged throughout the protocol. In the retrograde perfusion group, the intracellular pH level decreased to 6.4 +/- 0.1, and adenosine triphosphate and phosphocreatine levels decreased within the first 30 minutes of circulatory arrest and remained at low levels until the end of reperfusion. High-energy phosphates did not return to their initial levels during reperfusion. Histopathologic analysis of nine regions of the brain showed good preservation of cell structure in the anesthesia, hypothermic bypass, and antegrade perfusion groups. The retrograde perfusion group showed changes in all the regions examined.

CONCLUSIONS

The study shows that moderate hypothermic circulatory arrest at 28 degrees C with antegrade brain perfusion during circulatory arrest protects the brain but that retrograde cerebral perfusion at 28 degrees C does not protect the brain.