Prospective randomized neurocognitive and S-100 study of hypothermic circulatory arrest, retrograde brain perfusion, and antegrade brain perfusion for aortic arch operations

Deep hypothermic circulatory arrest: Alternative strategies for cerebral perfusion. A review article

Deep hypothermic circulatory arrest is an essential tool in the surgeon’s armamentarium. There are essentially three strategies to address cerebral ischemia during arrest periods. Early surgical case series pioneered the option of complete anoxia with deep hypothermia. Subsequent innovators introduced the concept of retrograde perfusion of the cerebral vessels through the venous system, and others have advocated the use of selective and non-selective antegrade perfusion of the cerebral arteries. Clinical studies assessing outcomes of the three approaches are compromised by small patient numbers, retrospective design and surgeon bias.

In this review, the authors will briefly discuss the conceptual basis of these strategies and the literature comparing these approaches in terms of key neurologic outcomes. The importance of this topic will emphasize the key role the perfusion community plays in establishing guidelines for best practice in circulatory arrest to go forward with education and research in this area.

Remote ischemic preconditioning protects the brain against injury after hypothermic circulatory arrest

BACKGROUND

Ischemic preconditioning (IPC) is a mechanism protecting tissues from injury during ischemia and reperfusion. Remote IPC (RIPC) can be elicited by applying brief periods of ischemia to tissues with ischemic tolerance, thus protecting vital organs more susceptible to ischemic damage. Using a porcine model, we determined whether RIPC of the limb is protective against brain injury caused by hypothermic circulatory arrest (HCA).

METHODS AND RESULTS

Twelve piglets were randomized to control and RIPC groups. RIPC was induced in advance of cardiopulmonary bypass by 4 cycles of 5 minutes of ischemia of the hind limb. All animals underwent cardiopulmonary bypass followed by 60 minutes of HCA at 18°C. Brain metabolism and electroencephalographic activity were monitored for 8 hours after HCA. Assessment of neurological status was performed for a week postoperatively. Finally, brain tissue was harvested for histopathological analysis. Study groups were balanced for baseline and intraoperative parameters. Brain lactate concentration was significantly lower (P<0.0001, ANOVA) and recovery of electroencephalographic activity faster (P<0.05, ANOVA) in the RIPC group. RIPC had a beneficial effect on neurological function during the 7-day follow-up (behavioral score; P<0.0001 versus control, ANOVA). Histopathological analysis demonstrated a significant reduction in cerebral injury in RIPC animals (injury score; mean [interquartile range]: control 5.8 [3.8 to 7.5] versus RIPC 1.5 [0.5 to 2.5], P<0.001, t test).

CONCLUSIONS

These data demonstrate that RIPC protects the brain against HCA-induced injury, resulting in accelerated recovery of neurological function. RIPC might be neuroprotective in patients undergoing surgery with HCA and improve long-term outcomes. Clinical trials to test this hypothesis are warranted.

Aortic Replacement via Median Sternotomy with Left Anterolateral Thoracotomy

Prevention of cerebral injury is an important consideration during repair of aortic arch aneurysm, and the major goal of cerebral protection techniques. We describe our surgical strategy for treatment of extended thoracic aortic aneurysms. Between January 2001 and June 2008, 17 men and 6 women, with a mean age of 67.9 ± 8.3 years, underwent total replacement of the arch and descending aorta. Six (26.1%) patients required emergency surgery. A median sternotomy with a left anterolateral thoracotomy provided a good visual field, and bilateral axillary arteries were preferentially used for systemic as well as selective cerebral perfusion. Two (8.7%) patients died in hospital. Prolonged mechanical ventilation was required for 7.3 ± 8.4 days after surgery in 17 patients who all recovered uneventfully. Permanent neurological dysfunction developed in 1 (4.3%) patient who died of sepsis 2 years after the operation. Our results suggest that total arch replacement through a median sternotomy plus a left anterolateral thoracotomy is helpful for extended replacement of the thoracic aorta as well as distal reoperation for dissecting type A aortic aneurysm. Perfusion via bilateral axillary arteries may improve cerebral protection.

Perioperative hypothermia: use and therapeutic implications

Perioperative cerebral ischemic insults are common in some surgical procedures. The notion that induced hypothermia can be employed to improve outcome in surgical patients has persisted for six decades. Its principal application has been in the context of cardiothoracic and neurosurgery. Mild (32-35 degrees C) and moderate (26-31 degrees C) hypothermia have been utilized for numerous procedures involving the heart, but intensive research has found little or no benefit to outcome. This may, in part, be attributable to confounding effects associated with rewarming and lack of understanding of the mechanisms of injury. Evidence of efficacy of mild hypothermia is absent for cerebral aneurysm clipping and carotid endarterectomy. Deep hypothermia (18-25 degrees C) during circulatory arrest has been practiced in the repair of congenital heart disease, adult thoracic aortas, and giant intracranial aneurysms. There is little doubt of the protective efficacy of deep hypothermia, but continued efforts to refine its application may serve to enhance its utility. Recent evidence that mild hypothermia is efficacious in out-of-hospital cardiac arrest has implications for patients incurring anoxic or global ischemic brain insults during anesthesia and surgery, or perioperatively. Advances in preclinical models of ischemic/anoxic injury and cardiopulmonary bypass that allow definition of optimal cooling strategies and study of cellular and subcellular events during perioperative ischemia can add to our understanding of mechanisms of hypothermia efficacy and provide a rationale basis for its implementation in humans.

Cerebrovascular response to continuous cold perfusion and hypothermic circulatory arrest

OBJECTIVE

Clinical and laboratory studies have documented changes in cerebrovascular resistance after hypothermic circulatory arrest, both with and without adjunctive cerebral perfusion modalities. This study was designed to clarify whether these changes are due to cerebral edema, resistance vessel abnormalities, or alterations in the cerebral microcirculation.

METHODS

Four mature swine underwent hypothermic circulatory arrest for 60 minutes, and 7 mature swine underwent cold cerebral perfusion for 60 minutes to simulate antegrade selective perfusion. All were rewarmed and weaned from cardiopulmonary bypass. Pial vascular diameter and reactivity were measured in vivo through a cranial window and ex vivo in an organ chamber; cerebral microvascular endothelium was studied in culture for release of vasoactive mediators. Cerebral water content was recorded.

RESULTS

Cold perfusion caused pial arteriole and venule constriction, whereas hypothermic circulatory arrest alone caused pial arteriole and venule dilatation. Cold perfusion caused a temporal loss of endothelium-dependent vasodilatation, most notably to bradykinin. Hypothermic circulatory arrest caused a loss of nitric oxide-mediated endothelium-dependent vasodilatation. Endothelium-independent vasoreactivity remained intact in both groups. Endothelial cells from the cold group had a vasoconstrictive secretory phenotype, whereas endothelial cells from the hypothermic circulatory arrest group had a vasodilatory phenotype. Cerebral water content was the same in both groups.

CONCLUSION

The increase in cerebrovascular resistance observed after cold cerebral perfusion is caused by resistance vessel constriction and may be promoted by an altered microcirculation. Hypothermic circulatory arrest alone is associated with endothelium-dependent vasoparesis. Both could contribute to cerebral injury in the early hours after operation.

Ascending and Transverse Aortic Arch Repair

Background— The benefit of retrograde cerebral perfusion (RCP) with profound hypothermic circulatory arrest has been subject to much debate. We examined our experience with ascending and transverse arch repairs to determine the impact of retrograde cerebral perfusion on stroke and mortality.

Methods and Results— Between August 1991 and June 2007, we performed 1107 repairs of the ascending and transverse aortic arch. RCP was used in 82% of cases (907 of 1107). Sixty-two percent were men (682 of 1107); median age was 64 years (range, 16 to 93 years). Perioperative variables were evaluated using univariate and multivariable analysis for mortality and stroke. Thiry-day mortality was 10.4% (115 of 1107). Stroke occurred in 2.8% (31 of 1107) of patients. Univariate risk factors for mortality were increasing age ( P <0.0001), history of coronary artery disease ( P =0.02), previous coronary artery bypass ( P =0.02), emergency status ( P <0.0001), acute dissection ( P =0.02), rupture ( P =0.0001), preoperative glomerular filtration rate, bypass time ( P <0.0001), crossclamp time ( P <0.007), RCP time ( P <0.0001), and packed red blood cell transfusions ( P =0.0001). Univariate risk factors for stroke included emergency status ( P <0.02), cerebrovascular disease ( P <0.02), and crossclamp time ( P <0.04). Independent risk factors for mortality were glomerular filtration rate <90 mL/min ( P =0.0004), emergency status ( P =0.006), rupture ( P =0.004), cardiopulmonary bypass time >120 minutes ( P <0.04), and packed red blood cell transfusions ( P =0.0002). Risk factors for stroke were emergency status ( P <0.009) and hypertension ( P <0.05). RCP was protective against mortality and stroke.

Conclusions— The use of RCP with profound hypothermic circulatory arrest was associated with a reduction in mortality and stroke. The use of RCP remains warranted during repairs of the ascending and transverse aortic arch.

Antegrade versus retrograde cerebral perfusion in relation to postoperative complications following aortic arch surgery for acute aortic dissection type A

BACKGROUND

Aortic arch surgery is impossible without the temporary interruption of brain perfusion and therefore is associated with high incidence of neurologic injury. The deep hypothermic circulatory arrest (HCA), in combination with antegrade or retrograde cerebral perfusion (RCP), is a well-established method of brain protection in aortic arch surgery. In this retrospective study, we compare the two methods of brain perfusion.

MATERIALS AND METHODS

From 1998 to 2006, 48 consecutive patients were urgently operated for acute type A aortic dissection and underwent arch replacement under deep hypothermic circulatory arrest (DHCA). All distal anastomoses were performed with open aorta, and the arch was replaced totally in 15 cases and partially in the remaining 33 cases. Our patient cohort is divided into those protected with antegrade cerebral perfusion (ACP) (group A, n = 23) and those protected with RCP (group B, n = 25).

RESULTS

No significant difference was found between groups A and B with respect to cardiopulmonary bypass-time, brain-ischemia time, cerebral-perfusion time, permanent neurologic dysfunction, and mortality. The incidence of temporary neurologic dysfunction was 16.0% for group A and 43.50% for group B (p = 0.04). The mean extubation time was 3.39 +/- 1.40 days for group A and 4.96 +/- 1.83 days for group B (p = 0.0018). The mean ICU-stay was 4.4 +/- 2.3 days for group A and 6.9 +/- 2.84 days for group B (p = 0.0017). The hospital-stay was 14.38 +/- 4.06 days for group A and 19.65 +/- 6.91 days for group B (p = 0.0026).

CONCLUSION

The antegrade perfusion seems to be related with significantly lower incidence of temporary neurological complications, earlier extubation, shorter ICU-stay, and hospitalization, and hence lower total cost.

Management of neurologic complications of thoracic aortic surgery

Neurologic complications of thoracic aortic surgery are strongly associated with increased morbidity and mortality. Identifying preoperative risk factors for neurologic injury may enable us to refine our perioperative approach, and to lessen or avoid these complications. Methods to identify stroke and spinal ischemia intraoperatively such as neurophysiologic monitoring may enable us to improve outcomes in these patients by immediately instituting measures to improve brain and spine perfusion. The development of both protocols and therapies to treat these complications has allowed us to mitigate and, at times, reverse neurologic injury both intraoperatively and postoperatively.

Perfusing the Cold Brain: Optimal Neuroprotection for Aortic Surgery

BACKGROUND

Selective cerebral perfusion (SCP) may enhance the neuroprotective benefits of hypothermia during aortic surgery. However, despite its widespread adoption, there is no consensus regarding optimal implementation of SCP. We used a survival porcine model to explore the physiologic characteristics and behavioral benefits of various protocols involving hypothermic circulatory arrest (HCA) and SCP.

METHODS

Thirty pigs (26.3 +/- 1.4 kg), cooled to 15 degrees C on cardiopulmonary bypass, using alpha-stat pH management (mean hematocrit 30%), were randomly allocated to differing brain protection strategies: 90 minutes of HCA (group A); 30 minutes of HCA, then 60 minutes of SCP (group B); or 90 minutes of SCP (group C). Using fluorescent microspheres and sagittal sinus sampling, cerebral blood flow (CBF [mL x 100g(-1) x min(-1)]) and cerebral metabolic rate for oxygen (CMRO2 [mL x 100g(-1) x min(-1)]) were assessed at baseline, after cooling, during SCP (where applicable), and for 2 hours after cardiopulmonary bypass. Neurobehavioral scores were assessed blindly from standardized videotaped sessions for 7 days postoperatively.

RESULTS

Cerebral blood flow was significantly higher (p = 0.0001) during SCP (60 and 90 minutes) if preceded by HCA. The CMRO2 was also significantly higher in group B versus group C (p = 0.016) at 60 minutes. The CMRO2 in all three groups rebounded promptly toward baseline after weaning from cardiopulmonary bypass. Postoperative neurobehavioral scores were significantly worse in group A.

CONCLUSIONS

Continuous SCP provides the best brain protection overall. However, an initial period of HCA does not seem to impair late outcome; perhaps the elevated CBF and CMRO2 observed reflect a beneficial cerebral response to a recoverable insult. Clearly, 90 minutes of HCA induces permanent brain injury, even in this carefully controlled setting.

Chronic ischemic cerebral white matter disease is a risk factor for nonfocal neurologic injury after total aortic arch replacement

OBJECTIVE

Leukoaraiosis (chronic ischemic white matter changes) on preoperative brain magnetic resonance imaging is common in patients having aortic arch surgery. This study sought to determine whether it is associated with adverse neurologic outcome in the postoperative period.

METHODS

Data were collected from a retrospective chart review of 142 patients in whom total aortic arch replacement was planned at the Cleveland Clinic between April 2000 and December 2004. All patients had preoperative brain magnetic resonance imaging evaluation. Leukoaraiosis severity was rated semiquantitatively using the Schelten's scale. Postoperative neurologic injuries were investigated by clinical examination and appropriate neuroimaging. They were stratified as type 1 (focal ischemic stroke) and type 2 (nonfocal neurocognitive changes, generalized seizures) injuries.

RESULTS

The following were independent predictors of type 1 neurologic injury: age (odds ratio 1.06 [1.01-1.13], P = .02) and moderate to severe aortic atheroma (odds ratio 4.4 [1.4-9.7], P = .012). Total white matter scores (odds ratio 1.16 [1.06-1.27], P = .002) and higher preoperative hemoglobin A1c levels (odds ratio 1.8 [1.00-3.50], P = .05) were significantly associated with type 2 neurologic injuries. Survival was 96%, and 4.2% had persistent focal neurologic deficits at the time of hospital discharge.

CONCLUSIONS

Leukoaraiosis is a significant independent predictor of nonfocal postoperative neurologic morbidity following aortic arch replacement surgery. Preoperative evaluation with magnetic resonance imaging allows identification of a patient subgroup at risk and implementation of strategies aimed at improving neurologic outcome.

Postcardiac Surgical Cognitive Impairment in the Aged Using Diffusion-Weighted Magnetic Resonance Imaging

BACKGROUND

Cardiac surgery is associated with cerebral dysfunction. While 1% to 2% of patients experience stroke, cognitive deficits are seen in more than half of patients. Given the high incidence of cognitive decline, it has become the endpoint of many cardiac surgery investigations. Because the elderly are at highest risk, this investigation sought to determine if there is a relationship between new ischemic changes demonstrated by diffusion-weighted magnetic resonance imaging (DW-MRI) and postoperative cognitive deficit in older patients.

METHODS

Fifty cardiac surgical patients (>65 years of age) underwent preoperative and postoperative neurocognitive examinations, including four to six week, postdischarge, follow-up. This evaluation assessed higher cortical function, memory, attention, concentration, and psychomotor performance. Objective evidence of acute cerebral ischemic events was identified using DW-MRI. Scans were analyzed by a neuroradiologist blinded to clinical status and cognitive outcomes.

RESULTS

Among patients with a mean age of 73 years, 88% demonstrated cognitive decline in the postoperative testing period while 32% showed evidence of acute perioperative cerebral ischemia by DW-MRI. At postdischarge follow-up, 30% of patients showed cognitive impairment. However, cognitive decline assessed postoperatively, or at a four to six week follow-up, was unrelated to the presence or absence of DW-MRI detected cerebral ischemia.

CONCLUSIONS

Postoperative neurocognitive impairment, assessed by standard means, is unrelated to acute cerebral ischemia detected by DW-MRI. This strongly suggests that cognitive decline after cardiac surgery is a function of underlying patient factors rather than perioperative ischemic events. This observation has broad implications for future investigation of strategies to prevent cardiac surgery-related neurologic injury.

Impact of volume status on the incidence of atrial fibrillation following aortic arch repair

We evaluated the volume status of patients undergoing aortic arch repair to determine the impact of fluid balance on risk of postoperative atrial fibrillation (AF). From 1993, 445 patients who underwent total aortic arch repair were enrolled in this study. Patients who had AF preoperatively or died within the 10th postoperative day (POD) were excluded. Volumes administered (input) and eliminated (output) through all routes were recorded, and fluid balance (input minus output) was calculated intraoperatively, on the day of surgery, and PODs 1-2. The incidence of new onset of AF was 53.9% (240/445). Total input on POD 1 was greater in patients developing AF than in those not developing it (3,372 +/- 90 vs 3,012 +/- 79; P = 0.0036), as was net fluid balance on POD 1 as well (-806 +/- 84 vs -558 +/- 90; P = 0.050). Blood transfusion volume was greater in patients developing AF than in those not developing it on POD 1 (1,285 +/- 89 vs 927 +/- 74; P = 0.003) and POD 2 (405 +/- 53 vs 227 +/- 47; P = 0.015). Increased input volume and net fluid balance on POD 1 are associated with an increased risk of postoperative AF in patients undergoing aortic arch surgery.

Surgical outcome of aortic arch repair for patients with Takayasu arteritis

BACKGROUND

Takayasu arteritis can cause segmental dilatation or stenosis of the aorta and its major branches, and surgical treatment of it is still difficult. Our objective was to review late results of aortic arch repair for patients with Takayasu arteritis.

METHODS

Between 1987 and 2003, 21 patients underwent aortic arch repair under circulatory arrest. Diagnosis was performed by pathologic study of specimens for all patients. Total aortic arch repair was performed in 12 patients with separated branched grafts and in 2 patients with the island technique. Selective cerebral perfusion was used in 12 patients and retrograde cerebral perfusion in 2 patients in this type of surgery. Hemiarch replacement using retrograde cerebral perfusion was performed in 7 patients. Craniocervical vascular stenosis was found in 7 patients and aneurysm in 5 patients. The elephant trunk technique was used in 10 patients. The follow-up period was 6.2 +/- 4.2 years.

RESULTS

There was one hospital death due to renal failure, and two late deaths, both of which were sudden. Late in follow-up, a patient who had undergone hemiarch replacement 12 years previously required total aortic arch repair for dilatation of the distal arch. Three patients required thoracoabdominal aortic repair and one patient descending aortic repair for residual aortic dilatation late in follow-up. Postoperative spinal infarction occurred in one patient who underwent hemiarch replacement.

CONCLUSIONS

Surgical and late outcomes of aortic arch repair under circulatory arrest appear favorable, though late dilatation of the residual aorta is a matter of concern.

Prediction and Incidence of Atrial Fibrillation After Aortic Arch Repair

BACKGROUND

Although atrial fibrillation is often associated with increased morbidity after open heart surgery, neither the incidence nor the clinical consequences of atrial fibrillation after aortic surgery has been well investigated. The goal of this study was to elucidate the risks for incidence of postoperative atrial fibrillation after aortic arch repair.

METHODS

From January 1993 to February 2004, 483 patients with atherosclerotic aortic arch aneurysm (n = 327) or aortic dissection (n = 156) underwent total aortic arch repair. All patients operated on as elective, urgent, or emergency aortic arch repair were included. One hundred sixteen patients received surgery on an emergency basis because of rupture or acute type A dissection. Twenty-four patients had atrial fibrillation preoperatively. Potential predictors of postoperative atrial fibrillation were estimated by a logistic regression model.

RESULTS

The incidence of postoperative, new onset of atrial fibrillation was 52.7% (242 of 459). The length of postoperative hospital stay was longer in patients with postoperative atrial fibrillation (48 +/- 52 days) than in patients without it (35 +/- 29 days; p = 0.001). The length of intensive care unit stay was also longer in patients with postoperative atrial fibrillation (12.1 +/- 23.2) than in patients without it (6.2 +/- 8.8; p = 0.002). Advanced age (p = 0.007; odds ratio = 1.34; 95% confidence interval: 1.14 to 1.62, per 10 years) was the only risk factor that correlated with postoperative new onset of atrial fibrillation.

CONCLUSIONS

Atrial fibrillation was not uncommon after aortic arch repair. Advanced age was the only preoperative risk factor for postoperative atrial fibrillation.

The elephant trunk procedure: uses in complex aortic diseases

PURPOSE OF REVIEW

The elephant trunk procedure is used for extensive aneurysms involving both the ascending aorta/aortic arch and the descending thoracic or thoracoabdominal aorta.

RECENT FINDINGS

This is a high-risk staged procedure; however, with current techniques in our most recent series the survival rate was 98% for the first operation and 92% for the second.

SUMMARY

With the more liberal use of hybrid procedures and endovascular stenting for the second stage of the elephant trunk procedure, the operation can be used more often in patients with severe comorbid disease, particularly respiratory problems.

Does the arterial cannulation site for circulatory arrest influence stroke risk?

BACKGROUND

We investigated whether axillary/subclavian artery inflow with a side graft decreases the risk of stroke versus cannulation at other sites during hypothermic circulatory arrest.

METHODS

Between January 1993 and May 2003, 1,352 operations with circulatory arrest were performed for complex adult cardiac problems. A single arterial inflow cannulation site was used in 1,336 operations, and these formed the basis for comparative analyses. Cannulation sites were axillary plus graft in 299 operations, direct cannulation of the aorta in 471, femoral in 375, innominate in 24, and axillary or subclavian without a side graft in 167. Retrograde brain perfusion was used in 933 (69%). A total of 272 (20%) were for emergencies, 432 (32%) were reoperations, and 439 (32%) were for dissections. A total of 617 (46%) had aortic valve replacement and 1,160 (87%) ascending, 415 arch (31%), and 248 descending (18%) aortic replacements. Indications also included arteriosclerosis (n = 301) and calcified aorta (n = 278). Primary comparisons were made by using propensity matching, and, secondarily, risk factors for stroke or hospital mortality were identified by multivariable logistic regression.

RESULTS

Stroke occurred in 6.1% of patients (81/1,336): 4.0% (12/299) of those had axillary plus graft and 6.7% who had direct cannulation (69/1,037; p = 0.09; p = 0.05 among propensity-matched pairs). Operative variables associated with stroke included direct aortic cannulation, aortic arteriosclerosis, descending aorta repair, and mitral valve replacement. The risk of hospital mortality was higher (11%; 42/375) for patients who had femoral cannulation than axillary plus graft (7.0%; 21/299; p = 0.06; p = 0.02 among propensity-matched pairs).

CONCLUSIONS

Axillary inflow plus graft reduces stroke and is our method of choice for complex cardiac and cardioaortic operations that necessitate circulatory arrest. Retrograde or antegrade perfusion is used selectively.

Neurocognitive functions after aortic arch repair with right brachial artery perfusion

BACKGROUND

Satisfactory neurologic outcome following aortic arch repair through right brachial artery perfusion is well established. However, how neurocognitive functions are affected following selective cerebral perfusion, still needs to be elucidated.

METHODS

In a period between April 2002 and March 2003, 22 patients (19 male, 3 female, with a mean age of 46.8 +/- 12; range: 26 to 70 years old), underwent aortic arch repair using right brachial artery low flow (8 to 10 mL x kg(-1) x min(-1)) selective antegrade cerebral perfusion under moderate hypothermia (26 degrees C). There were 6 Stanford type-A dissections and 16 ascending aortic aneurysms. All patients were evaluated preoperatively and postoperatively (at seventh day and second month) for neurocognitive functions.

RESULTS

There was no operative mortality. The average cardiopulmonary bypass time was 115.0 +/- 24.2 minutes and the average antegrade cerebral perfusion time was 29.8 +/- 7.1 minutes (19 to 38 minutes). No major neurologic deficit was observed in the postoperative period. In terms of neurocognitive test results, between the preoperative and postoperative assessments for both hemispheric cognitive functions no deterioration was detected.

CONCLUSIONS

The low-flow selective antegrade cerebral perfusion technique through the right brachial artery may safely be used for the great majority of patients undergoing aortic arch repair without causing deteriorations in neurocognitive functions.

Neurocognitive outcome after retrograde cerebral perfusion

BACKGROUND

Neurocognitive outcome in patients undergoing thoracic aortic surgery using retrograde cerebral perfusion (RCP) remains uncertain.

METHODS

Forty-two patients undergoing thoracic aortic surgery using RCP were enrolled in the study. The patients' neurocognitive state was assessed by the revised Wechsler Adult Intelligence Scale (WAIS-R) a few days before operation, at 2 to 3 weeks, and at 4 to 6 months after operation.

RESULTS

There were no stroke, seizure, and hospital death. Significant performance deterioration was observed in digit span, arithmetic, and picture completion of the WAIS-R subtests. Bivariate comparison showed that older age (late vocabulary, late similarities, and late object assembly), longer RCP time (early picture arrangement, and early block design), later awake time (early and late picture arrangement, and early block design), longer respirator use (early and late digit span, late picture arrangement), longer ICU time (late picture completion, early and late picture arrangement, and early block design), and longer hospital stay (early picture arrangement) were significantly associated with the decline in neurocognitive performance. Stepwise logistic regression analysis disclosed that older age (late similarities and late object assembly), later awake time (late picture arrangement), and longer respirator use (early and late digit span, and late picture arrangement) were most predictive for the decline in neurocognitive performance.

CONCLUSIONS

On average, digit span, arithmetic, and picture completion tests were most sensitive in detecting the decline in neurocognitive performance. The relationship between the duration of RCP and neurocognitive test results was not significant.

Determination of cerebral blood flow dynamics during retrograde cerebral perfusion using power M-mode transcranial Doppler

BACKGROUND

Retrograde cerebral perfusion (RCP) during profound hypothermic circulatory arrest has been used as an adjunct for cerebral protection for repairs of the ascending and transverse aortic arch. Transcranial Doppler ultrasound has been used to monitor cerebral blood flow during RCP with varying success. The purpose of this study was to characterize cerebral blood flow dynamics during RCP using a new mode of monitoring known as transcranial power motion-mode (M-mode) Doppler ultrasound.

METHODS

Data on pump-flow characteristics and patient outcomes were collected prospectively for patients undergoing ascending and transverse aortic arch repair. Retrograde cerebral perfusion during profound hypothermic circulatory arrest was used for all operations. Intraoperative cerebral blood flow dynamics were monitored and recorded using transcranial power M-mode Doppler ultrasound.

RESULTS

Between August 2001 and March 2002, we used transcranial power M-mode Doppler ultrasound monitoring for 40 ascending and transverse aortic arch repairs during RCP. Mean RCP time was 32.2 +/- 13.8 minutes. Mean RCP pump flow and RCP peak pressure for identification of cerebral blood flow were 0.66 +/- 0.11 L/min and 31.8 +/- 9.7 mm Hg, respectively. Retrograde cerebral blood flow during RCP was detected in 97.5% of cases (39 of 40 patients) with a mean transcranial power M-mode Doppler ultrasound flow velocity of 15.5 +/- 12.3 cm/s. In the study group, 30-day mortality was 10.0% (4 of 40 patients). The incidence of stroke was 7.6% (3 of 40 patients); the incidence of temporary neurologic deficit was 35.0% (14 of 40 patients).

CONCLUSIONS

Transcranial power M-mode Doppler ultrasound consistently demonstrated retrograde middle cerebral artery blood flow during RCP. Transcranial power M-mode Doppler ultrasound can provide optimal RCP with individualized settings of pump flow.

Multimodal protocol influence on stroke and neurocognitive deficit prevention after ascending/arch aortic operations

BACKGROUND

Various techniques are used for brain protection during aortic surgery. Rather than evaluate each factor separately, we evaluated the early outcome of a multimodal protocol (mannitol, thiopental, MgSO4, lidocaine, CO2 field flooding, Leukoguard filter, head ice packing, electroencephalographic arrest at 20 degrees C, alpha-stat, increasing right subclavian artery cannulation, and antegrade/retrograde brain perfusion) for brain protection.

METHODS

Prospectively collected data were analyzed on 403 ascending or arch aortic operations including 199 (49%) arch replacements conducted between July 25, 1991, and September 25, 2001. The mean age was 61.6 years (range 22 to 91 years); 48 (12%) had Marfan syndrome; 141 (35%) had dissection; 134 (33%) had composite grafts inserted; and 138 (34%) had concurrent coronary bypasses performed.

RESULTS

Stroke occurred in 2.0% (8/403) (3 permanent, 5 transient), clinical neurocognitive deficits in 2.5% (10/403) either by testing or patient complaint 2 to 3 weeks after surgery, and 98% (395/403) were 30-day survivors. Univariate predictors of stroke, neurocognitive decline, or death were the following: for stroke, aorta symptom severity grade (1 to 4) (p = 0.001), pump time (p = 0.001), arrest time (p = 0.001), macroscopic atheroma (p = 0.041), concurrent descending/thoracoabdominal aneurysm (p = 0.036), and highest blood rewarming temperature (p = 0.043); for neurocognitive decline, degree of cooling (p = 0.046), pump time (p = 0.001), cooling time (p = 0.001), day extubated (p = 0.042), and antegrade brain perfusion (p = 0.004); for death, pump time (p = 0.001) and clamp time (p = 0.011). The multivariable independent predictors of stroke, neurocognitive decline, or death were the following: for stroke, aorta symptoms grade (p = 0.025), peripheral vascular disease (p = 0.043), and pump time (p = 0.015); neurocognitive decline, preoperative New York Heart Association dyspnea class (p = 0.022), pump time (p = 0.05), arrest time (p = 0.06), day extubated (p = 0.042), and antegrade perfusion (p = 0.023); and for death, pump time (p = 0.018).

CONCLUSIONS

Pump time continues to be the most important predictor of adverse events. The benefit of antegrade or retrograde perfusion remains unproven, partly because of the low event rate (< 2.5%) but may be beneficial for prolonged circulatory arrest. Embolic material either from macroscopic atheroma, descending or thoracoabdominal aneurysms, or associated with peripheral vascular disease, increases the risk of stroke. Preoperative symptoms influence outcome.

Progress in ascending and aortic arch surgery: minimally invasive surgery, blood conservation, and neurological deficit prevention

BACKGROUND

Herein are described recent developments in aortic surgery techniques and the improved results.

METHODS

Of 403 ascending and aortic arch operations, 68 patients underwent minimally invasive aortic surgery including 23 for aortic dissection, 5 for Marfan syndrome, 29 reoperations, and 39 with hypothermic arrest. Blood conservation methods were used in 187 of the 403 patients (46.5%). Aortic valve procedures were used in 267 (66.2%), including 51 (12.7%) valve-preserving operations. A protocol for stroke and neurocognitive deficit prevention was used in an attempt to prevent neurologic deficits. Data were prospectively collected and included new neurocognitive events either by formal testing (n = 35) or by informal questioning.

RESULTS

Stroke occurred in 2.0% (8 of 403); clinical gross neurocognitive deficits in 2.5% (10 of 403) with a 98% 30-day survival. For those patients undergoing the minimally invasive operation 1 hospital death occurred (98.5% survival). Homologous operative transfusions were required in only 12% of blood conservation patients (23 of 187) and their postoperative intubation time, intensive care unit (ICU) stay, and hospital stay were significantly shorter (p < 0.04).

CONCLUSIONS

Minimally invasive surgery is particularly useful for reoperations. The blood conservation methods appear to be beneficial and the number of neurologic deficits is low with the current protocol.