Risk analysis for aortic surgery using hypothermic circulatory arrest with retrograde cerebral perfusion

Surgical Outcome of Subtypes of Aortic Arch Dissection

This study was conducted to investigate if the site of primary intimal tear involving the aortic arch and the surgical approach affect the early and late results of total aortic arch replacement. Between 1993 and November 2001, 42 patients underwent graft replacement of the total aortic arch for aortic dissection. Their mean age was 51.9 ± 9.8 years, and 38 of them were male. All operations were performed under hypothermic circulatory arrest with retrograde cerebral perfusion. Hospital mortality was 28.6% (12 patients). There were 2 late deaths. Multivariate analysis showed that chronic obstructive pulmonary disease and ascending aortic replacement with or without valve replacement were significant independent determinants of early death. Patients with the intimal tear originating in the ascending aorta showed a tendency towards lower 7-year survival rates than those with a tear at other aortic sites or with multiple tears, while the presence of chronic obstructive pulmonary disease adversely affected early and late outcomes. We conclude that the primary site of an intimal tear that involves the aortic arch affects early and late survival, but concomitant non-cardiac diseases play an even more important role in the early outcome as they increase the complexity of the operation.

Central Nervous System Protection in Cardiac Surgery

Neurological dysfunction and stroke following cardiac surgery and thoracic surgery requiring hypothermic circulatory arrest is a well-defined problem. The original studies in CABG patients identified risk factors, such as prior stroke and lower educational level. There is older evidence suggesting that higher perfusion pressures during cardiopulmonary bypass are helpful. Hyperthermia during rewarming on cardiopulmonary bypass and postoperative hyperthermia have been associated with adverse cognitive outcomes. Glucose management intraoperatively remains controversial, but most now advocate for moderate glucose control using insulin, if required. The subset of patients having thoracic aortic surgery requiring periods of aortic discontinuity are particularly problematic. A cerebral protection strategy should be determined, and this may include hypothermic circulatory arrest, selective cerebral perfusion, or retrograde cerebral perfusion. All of these techniques have been associated with good surgical outcomes, but there is little information on cognitive outcomes of thoracic aortic surgery.

Elective hypothermic circulatory arrest to address aortic pathology is safe for the elderly

BACKGROUND

Due to assumptions of excessive risk, hypothermic circulatory arrest (HCA) has been considered prohibitive in elderly patients. However, as more elderly patients are referred for assessment of difficult aortic valve, ascending aorta, and aortic arch pathology, the risk of HCA in these patients needs to be addressed. We hypothesized that the use of HCA would not increase mortality or complications in elderly patients compared to younger counterparts.

METHODS

We retrospectively reviewed the charts of adult patients who underwent elective HCA between January 1995 and June 2007. Of 147 procedures, 45 patients were >or=75 years old. These patients were compared to their younger counterparts in terms of comorbidities, operations, and complications.

RESULTS

Comparing patients >or=75 years old to their younger counterparts revealed no significant differences in outcomes including nearly identical rates of confusion (>or=75 15% vs <75 9%, p > 0.5) and stroke (>or=75 11% vs <75 7%, p > 0.2). There was also no difference in 30-day mortality (>or=75 7% vs <75 7%, p = 0.9). Lengths of hospital stays and intensive care unit stays were longer in the older patients, but this was not statistically significant.

CONCLUSION

In this study, elderly patients faired well with HCA compared to younger patients. These data suggest that the use of HCA is safe in selected elderly patients. Elderly patients should be considered for indicated procedures of the aortic valve, ascending aorta, and aortic arch regardless of age.

Resection of the Descending Thoracic Aorta: Outcomes After Use of Hypothermic Circulatory Arrest

BACKGROUND

Use of hypothermic circulatory arrest (HCA) for operations on the descending thoracic aorta is controversial. While deep hypothermia may provide better end-organ and spinal cord function, prolonged cardiopulmonary bypass and circulatory arrest may increase morbidity. This study assessed outcomes after use of HCA for descending thoracic aortic resection in a large cohort of consecutive patients.

METHODS

Hypothermic circulatory arrest was utilized if arch or extensive descending thoracic aortic resection was required, or if aortic pathology precluded cross-clamping. One hundred thirty-two patients (mean age, 61.3 years) were identified. Diagnosis included fusiform (41.2%) or saccular aneurysm (10.7%) and acute (4.6%) or chronic (38.9%) dissection. Twenty-one patients presented with rupture. Arch resection (distal arch 100, total arch 11) was required in 111 patients (84.1%). The extent of descending thoracic aortic resection (required in 94%) included proximal third in 41 patients, proximal two-thirds in 6, and complete thoracic aorta in 77. The proximal anastomosis was performed with total body HCA while the distal anastomosis was constructed with lower body HCA only (duration upper body HCA 33.7 +/- 8.0 minutes; total duration lower body HCA 71.3 +/- 24.2 minutes).

RESULTS

Thirty-day mortality was 6.0%. Neurologic events included stroke (6.8%) and permanent lower extremity paralysis-paresis (4.5%). Temporary dialysis was needed in 7 (5.3%), though only 2 patients required permanent dialysis (1.9%). Independent predictors of a composite endpoint of death, stroke, permanent paralysis, or dialysis included duration of lower body HCA (p = 0.03) and major postoperative infection (p = 0.003).

CONCLUSIONS

Adjunctive use of deep hypothermic circulatory arrest for descending thoracic aortic resection affords excellent preservation of end-organ and spinal cord function with acceptable rates of mortality and significant morbidity.

Methods of cerebral protection in surgery of the thoracic aorta

During the last decade, a considerable increase in the number of operations on the thoracic aorta has been observed. Although patient's outcomes have improved considerably, this surgery is still associated with significant morbidity and mortality due to neurological complications. Various methods have been proposed and widely used as means to protect the brain from ischemic damage. This review summarizes the principal methods of cerebral protection, describes the advantages and disadvantages of each method and their impact on patient outcomes, and discusses the different surgical techniques proposed to minimize the risk of cerebral injuries.

Time and Risk Analysis for Acute Type A Aortic Dissection Surgery Performed by Hypothermic Circulatory Arrest, Cerebral Perfusion, and Open Distal Aortic Anastomosis

BACKGROUND

Hypothermic total circulatory arrest, retrograde or antegrade cerebral perfusion, and open distal anastomosis are important stages of surgical management and cerebral protection for acute type A dissections. Among the factors that influence survival are the transfer time to hospital from the onset of symptoms, in-hospital transfer time to operation, organ malperfusion, preoperative risk factors, and intraoperative variables. The aim of this study was to analyze time and risk factors during surgical management.

METHODS

Between September 1996 and March 2002, a total of 26 patients with acute type A aortic dissection were operated. Sixteen patients (61.5%) were male and mean age was 49 ( 13.1 years (range: 26-68). The diagnosis was based on clinical examination, telecardiography, transthoracic echocardiography, computerized tomography, and angiography. Hypothermic total circulatory arrest, retrograde or antegrade cerebral perfusion and open distal anastomosis were used during the procedures. Operative techniques were as follows: supracoronary ascending aortic replacement (17 patients), aortic root and ascending aortic replacement with flanged composite grafting technique (5 patients), replacement of ascending aorta and hemiarcus (1 patient), aortic root and ascending aortic replacement with modified Bentall technique (1 patient), replacement of ascending aorta and arcus (1 patient), and total arcus replacement with elephant trunk technique and modified Bentall procedure (1 patient).

RESULTS

The early postoperative mortality rate within the first 30 days was 26.9%, and the late postoperative mortality rate was 15.8%. Two patients (7.7%) developed major neurological complications during the postoperative period. Time to admission, durations of total circulatory arrest, cross-clamp, cardiopulmonary bypass, and intubation were longer, and postoperative blood loss was greater in patients who died during early postoperative period, although the differences did not reach statistical significance. Duration of total circulatory arrest was longer in patients who developed neurological dysfunction compared to patients without this complication; this difference also did not reach statistical significance.

CONCLUSIONS

Total circulatory arrest, cerebral perfusion, and open distal anastomosis are reliable options in the surgical management of acute type A aortic dissections. With open distal anastomosis aortic arcus can be evaluated, distal anastomosis can be performed more easily, and postoperative neurological recovery is hastened. In the present study, although statistical significance could not be reached due to limited sample size, the time to admission, durations of total circulatory arrest, cross-clamp, and cardiopulmonary bypass, and the amount of postoperative chest output seem to influence postoperative survival.

Influence of retrograde cerebral perfusion during aortic arch procedures

BACKGROUND

Recent reports suggest dramatic improvement in outcome using retrograde cerebral perfusion (RCP) during operations on the arch; however, most investigators have compared contemporary results with historic controls. The purpose of this study was to determine the impact of RCP within the same patient population and time period.

METHODS

From 1996 to 2000, 72 consecutive patients underwent an aortic arch procedure using hypothermic circulatory arrest (HCA) (31 acute dissection or rupture, 41 chronic dissection or aneurysm). Supplemental RCP was used in 36 patients, whereas 36 patients had HCA alone. The groups were similar in age, emergent status, and cardiopulmonary bypass time (p > 0.08), but HCA time was higher with RCP (40 +/- 15 minutes versus 29 +/- 14 minutes; p < 0.001).

RESULTS

Operative mortality was 10% +/- 4% (+/- 70% confidence limit), and adverse outcomes (death or cerebrovascular accident) occurred in 14% +/- 4%, but there was no difference between HCA alone (8% +/- 5%, 14% +/- 6%) and HCA with RCP (11% +/- 5%, 14% +/- 6%) (p > 0.73). The incidence of transient neurologic dysfunction was also similar (HCA alone, 11% +/- 5%; HCA with RCP, 17% +/- 6%; p > 0.73). Multivariate risk factors for mortality included emergency operation and HCA time (p < 0.02). Risk factors for adverse outcome included emergency operation and atheromatous ascending aorta (p < 0.03). Risk factors for transient neurologic dysfunction included preexisting cerebrovascular disease and rewarming retrograde (femoral) rather than antegrade (through the graft) (p < 0.03).

CONCLUSIONS

Supplemental RCP during HCA did not decrease mortality or neurologic complications. Retrograde rewarming through the femoral artery after completion of the distal anastomosis increased transient neurologic dysfunction. Therefore, RCP remains optional, but reperfusion should be antegrade to improve neurologic recovery.

Surgical repair of ruptured thoracic and thoracoabdominal aortic aneurysms

BACKGROUND

Rupture is the single most common cause of death in patients with thoracic aortic and thoracoabdominal aneurysm (TAA/TAAA) and is almost uniformly fatal.

METHODS

This was a retrospective review of patients admitted to a single practice with rupture of a TAA/TAAA between 1993 and 2000.

RESULTS

Twenty-two consecutive patients with a leaking TAA/TAAA were identified. The aetiology of rupture was either secondary to a degenerative TAAA or a type B dissection. Seventeen patients underwent surgery; one had a Crawford extent I, seven an extent II, one an extent III and two an extent IV TAAA. Six patients had an acute type B dissection with rupture in the upper descending thoracic aorta. The 30-day survival rate was 88 per cent (15 of 17 patients). Actuarial survival at 1 year in patients who had surgery was 65 per cent. Survival at 1 year for all presenting patients who consented to surgery was 40 per cent. Median survival was greater than 36 months.

CONCLUSION

As a result of improving medical care, more patients with a contained rupture of a TAA/TAAA may present for treatment. Surgery is complex and requires specialist teams for optimal care.

Cerebral Protection During Surgery of the Aortic Arch

The most significant challenge in surgical repair of the aortic arch (transverse thoracic aorta) is to protect the brain from ischemic injury. During the portion of the procedure when the brachiocephalic vessels are at tached to a graft, there is an obligatory interruption in the normal path of circulation to the brain. Various strategies are used to overcome the potential for brain injury during discontinuity between the aorta and the cerebral circulation. These include deep hypothermic circulatory arrest, retrograde cerebral perfusion, and selective anterograde cerebral perfusion. Pharmaco logic adjuncts to these procedures are also used to further enhance brain protection. This review ad dresses the relative merits of these techniques as means of cerebral protection.

Retrograde cerebral perfusion as a method of neuroprotection during thoracic aortic surgery

Retrograde cerebral perfusion is commonly used as an adjunct to hypothermic circulatory arrest to enhance cerebral protection during thoracic aortic surgery. This review summarizes a large number of studies that demonstrate a spectrum of beneficial, neutral, and detrimental effects of retrograde cerebral perfusion in humans and experimental animal models. It remains unclear whether retrograde cerebral perfusion provides effective cerebral perfusion, metabolic support, washout of embolic material, and improved neurological and neuropsychological outcome.

Retrograde cerebral perfusion during thoracic aortic surgery and late neuropsychological dysfunction

OBJECTIVE

Retrograde cerebral perfusion (RCP) is commonly used in thoracic aortic surgery, ostensibly to provide metabolic support, maintain cerebral hypothermia and/or wash out particulate emboli. We tested the hypothesis that RCP would affect neuropsychological outcome in a clinical cohort.

METHODS

Ninety-four patients undergoing elective thoracic aortic repairs requiring deep hypothermic circulatory arrest consented to participate in this study. These patients underwent preoperative neuropsychological evaluation and comprise the reference group. Fifty-six of these patients also underwent neuropsychological evaluation several weeks postoperatively, 12 of whom (21%) had RCP. The neuropsychological domains tested were attention, processing speed, memory, executive function, and fine motor function. A global assessment of impairment, negative neuropsychological outcome (NNO), was defined as a postoperative decrease in function in two or more neuropsychological domains for patients with at least three domains tested both pre- and postoperatively (n=48). The relationship of three potential predictors (RCP, cerebral ischemia time and patient age) to negative outcomes was analyzed using Wilcoxon two-sample tests, chi(2) tests, Mantel-Haenszel tests and multiple logistic regression. P<0.05 was considered significant.

RESULTS

Memory dysfunction and NNO had strong associations with RCP. This effect remained significant when controlling separately for age and cerebral ischemia time.

CONCLUSIONS

The effects of RCP are difficult to distinguish from those of age and prolonged cerebral ischemia time, because complex thoracic aortic repairs are associated with advanced age, prolonged cerebral ischemia and use of RCP. Despite this limitation, these preliminary data indicated that RCP had no beneficial effect (and most likely a negative effect) upon cognitive outcome.

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.