Temporary neurological dysfunction after deep hypothermic circulatory arrest: a clinical marker of long-term functional deficit

[Thoracic aortic surgery with circulatory arrest and cold cerebral perfusion]

BACKGROUND

This study was undertaken to identify pre- and perioperative risk factors to mortality and permanent neurological dysfunction (PND) and temporary neurological dysfunction (TND) in a large patient cohort, all operated under moderate hypothermic circulatory arrest (HCA) and selective antegrade cerebral perfusion (SACP) in a single centre.

PATIENT AND METHODS

Between November 1999 and March 2006, 319 patients at a median age of 65 years (range 21-86, 201 male) underwent elective aortic arch surgery with moderate HCA at 25 degrees C and additional SACP at 14 degrees C. Sixty-nine had additional coronary artery bypass grafts or valve procedures. Ninety-four (29%) had total arch repair. Statistical analysis was carried out to determine the risk factors for 30-day mortality as well as for TND and PND.

RESULTS

Overall mortality was 7.8% (15% in cases with repeat surgery vs 4.8% in nonrepeats, P=0.002). Twenty-seven (8.5%) suffered from PND, and six (22%) died during hospital stay (P=0.004). There was TND detected in 32 patients (10%). Stepwise logistic regression revealed age (P=0.001, OR 1.09/year), repeat surgery (P=0.008, OR 5.04), preoperative neurological events (P=0.004, OR 3.44), CAD (P=0.051, OR 3.58), and cardiopulmonary bypass duration (P<0.001, OR 1.01/min) as risk factors for mortality. The PND was associated with preoperative renal insufficiency (P=0.026, OR 3.34) and operation duration (P<0.001, OR 1.01/min), whereas TND occurred in patients with coronary artery disease (P=0.04, OR 2.41), and prolonged cardiopulmonary bypass duration (P=0.05, OR 1.01/min).

CONCLUSION

Thoracic aortic surgery including aortic arch using HCA and SACP can be performed with excellent results in elective patients, especially those without previous surgery. Nevertheless PND is associated with high hospital mortality. Neurological complications seem to be strongly associated with general atherosclerotic changes as well as the extent of surgery.

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.

Biomarker evidence for mild central nervous system injury after surgically-induced circulation arrest

Previously, we identified 14-3-3 beta and zeta isoforms and proteolytic fragments of alpha-spectrin as proteins released from degenerating neurons that also rise markedly in cerebrospinal fluid (CSF) following experimental brain injury or ischemia in rodents, but these proteins have not been studied before as potential biomarkers for ischemic central nervous system injury in humans. Here we describe longitudinal analysis of these proteins along with the neuron-enriched hypophosphorylated neurofilament H (pNFH) and the deubiquitinating enzyme UCH-L1 in lumbar CSF samples from 19 surgical cases of aortic aneurysm repair, 7 involving cardiopulmonary bypass with deep hypothermic circulatory arrest (DHCA). CSF levels of the proteins were near the lower limit of detection by Western blot or enzyme-linked fluorescence immunoassay at the onset of surgical procedures, but increased substantially in a subset of cases, typically within 12-24 h. All cases involving DHCA were characterized by >3-fold elevations in CSF levels of the two 14-3-3 isoforms, UCH-L1, and pNFH. Six of 7 also exhibited marked increases in alpha-spectrin fragments generated by calpain, a protease known to trigger necrotic neurodegeneration. Among cases involving aortic cross-clamping but not DHCA, the proteins rose in CSF preferentially in the subset experiencing acute neurological complications. Our results suggest the neuron-enriched 14-3-3beta, 14-3-3zeta, pNFH, UCH-L1, and calpain-cleaved alpha-spectrin may serve as a panel of biomarkers with clinical potential for the detection and management of ischemic central nervous system injury, including for mild damage associated with surgically-induced circulation arrest.

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.

Brain oxymetry in the operating room: current status and future directions with particular regard to cytochrome oxidase

Near-infrared spectroscopy (NIRS) is a cerebral monitoring method that noninvasively and continuously measures cerebral hemoglobin oxygenation and the redox state of cytochrome oxidase using highly tissue-permeable near-infrared light. This technique now has wide clinical application, and its usefulness in the measurement of cerebral hemoglobin oxygenation has been confirmed under global cerebral injury and/or hypoxemic hypoxia; however, regional cerebral infarction located far from the monitoring site may not be detected by NIRS. Furthermore, the specificity and accuracy of the measurement of the redox state of cytochrome oxidase remain controversial. We apply NIRS to both animal and clinical investigations. Based on these results, we discuss the significance of the measurement of cerebral hemoglobin oxygenation and cytochrome oxidase in vivo and in clinical medicine. Using our algorithm, cytochrome oxidase signals are unaffected by hemoglobin signals, even when hematocrit values change from 35 to 5% under cardiopulmonary bypass in a dog model. In the clinical study, cytochrome oxidase during surgery is likely to be a good (though not perfect) predictor of postoperative cerebral outcome. NIRS appears to be a promising technology, but additional investigations are required to establish its clinical efficacy and justify its routine use during operative and perioperative periods.

Initial experience of an arterial shunt for bilateral antegrade cerebral perfusion during hypothermic circulatory arrest

PURPOSE

The purpose of this study is to describe an intravessel cerebral shunt that allows perfusion of both cerebral hemispheres through the axillary artery.

DESCRIPTION

The cerebral shunt is a 10-cm to 12-cm long cannula with a lumen for blood perfusion and two balloons, one at each distal end. The proximal balloon is adapted for retaining the proximal end of the catheter in the innominate artery; the second inflatable balloon is adapted for retaining the distal end of the catheter into the left common carotid artery.

EVALUATION

Three consecutive patients received bilateral brain perfusion through the right axillary artery with the use of this cerebral shunt.

CONCLUSIONS

The cerebral shunt allowed bilateral cerebral perfusion as verified with cerebral oximetry in the absence of any evident neurologic dysfunction.

Cognitive brain function after hypothermic circulatory arrest assessed by cognitive P300 evoked potentials

BACKGROUND

The role of hypothermic circulatory arrest (HCA) in cardiovascular surgery is controversial and assumed to result in neurocognitive dysfunction that is not always detected by standard clinical observation. We assessed cognitive P300 visual evoked potentials (P300) in patients undergoing either HCA or coronary artery bypass grafting (CABG) to elucidate whether HCA was associated with postoperative cognitive decline.

METHODS

Thirteen patients undergoing either aortic arch replacement (n=4) or pulmonary thromboendarterectomy (n=9) using HCA (mean: 28+/-11 min, 22+/-2 degrees C) were studied. They were compared to 13 patients undergoing on-pump CABG. P300s were measured 1 day before and 1 week after the operation. We assessed an area under the curve (AUC) between 280 and 600 ms and center of this area [Ct (time), Cv (voltage)]. The ratio of these parameters acquired by target (TG) and non-target (NTG) stimulus (TG/NTG) was calculated to assess concentration on TG stimulus and defined as concentration index (CI: CI(AUC), CI(Ct), and CI(Cv)).

RESULTS

There was no significant difference in preoperative characteristics between groups. There were neither strokes nor hospital deaths. Preoperatively, the HCA group could not concentrate on target stimulus as well as the control group in frontal leads (CI(AUC) and CI(Cv) were lower in HCA group than in control group). However, the HCA group could concentrate on target stimulus better than the control group postoperatively because postoperative CI(AUC) (pre-operation: 1.1+/-0.5 to post-operation: 1.7+/-0.4, P=.02) and CI(Cv) (1.1+/-0.4 to 1.6+/-0.4, P=.01) were significantly improved in the HCA group, whereas these were significantly impaired in the control group (CI(AUC): 1.6+/-0.6 to 1.3+/-0.4, P=.03, CI(Cv): 1.5+/-0.5 to 1.2+/-0.3, P<.01). Postoperative CI(Ct) in the HCA group were significantly impaired in all leads. The duration of HCA did not correlate with any values of postoperative P300. No specific trends were observed in either preoperative or postoperative P300 values between patients with or without postoperative temporary neurological dysfunction (one in each group). Postoperative improvement of CI(AUC) and CI(Cv) in Fz lead were found in 85 and 69% in the HCA group and 23 and 23% in the control group, respectively (CI(AUC): P<.01, CI(Cv): P<.05).

CONCLUSIONS

P300 detected no significant neurocognitive impairment due to the relatively brief period of HCA (approximately 28 min).

Impact of Perfusion Strategy on Neurologic Recovery in Acute Type A Aortic Dissection

BACKGROUND

The optimal perfusion strategy during surgery of acute type A aortic dissection is controversial. The purpose of this study was to determine the impact of retrograde cerebral perfusion during hypothermic circulatory arrest on short-term and long-term outcome in this specific patient population.

METHODS

Between 1984 and 2005, 175 consecutive patients underwent repair of an acute type A dissection. Three different surgical approaches were used: aortic cross-clamping without hypothermic circulatory arrest in 50 (29%), hypothermic circulatory arrest alone in 69 (39%), and hypothermic circulatory arrest with supplemental retrograde cerebral perfusion in 56 (32%).

RESULTS

Operative mortality was 18% +/- 3% (+/- 70% confidence interval), and adverse outcomes (death or cerebrovascular accident) occurred in 21% +/- 3% of patients (p = 0.97 between groups). Multivariate analysis identified valve replacement (p = 0.04), preoperative flow complications (p = 0.03), and non-Marfan syndrome (p = 0.04) as predictors of operative mortality. Intraoperative dissection (p < 0.001) and history of cerebrovascular disease (p = 0.02) were predictors for permanent neurologic deficit, and retrograde cerebral perfusion was shown to have a protective effect on transient neurologic deficits (p = 0.008). Kaplan-Meier survival was 75% +/- 3% at 1 year (131 patients at risk), 63% +/- 4% at 5 years (87 patients at risk), and 49% +/- 4% at 10 years (48 patients at risk) and was independent of surgical approach (p = 0.37). Long-term survival was diminished with increased age (p < 0.001), earlier operative year (p < 0.001), and coronary artery disease (p = 0.02).

CONCLUSIONS

The current investigation suggests improved neurologic recovery with circulatory arrest and supplemental retrograde cerebral perfusion. Operative mortality and long-term survival were comparable among groups.

Integrated Total Arch Replacement Using Selective Cerebral Perfusion: A 6-Year Experience

BACKGROUND

The purpose of this study was to evaluate the recent outcome of integrated total arch replacement using antegrade selective cerebral perfusion with right axillary artery perfusion.

METHODS

Between 2000 and 2005, 305 patients underwent elective total arch replacement for arch or distal arch aneurysm using a Dacron (DuPont, Wilmington, DE) quadrifurcated prosthesis through a median sternotomy. There were 34 dissecting and 271 nondissecting aneurysms. Brain protection was standardized using antegrade selective cerebral perfusion with right axillary artery cannulation at 20 degrees to 28 degrees C. Risk factors for early mortality and neurologic complications were investigated using multivariate logistic regression analyses.

RESULTS

The durations of hypothermic circulatory arrest, myocardial ischemia, selective cerebral perfusion, cardiopulmonary bypass, and surgery were 60.9 +/- 16.8, 125.2 +/- 39.3, 150.1 +/- 39.0, 229.8 +/- 91.4, and 466.4 +/- 175.8 minutes, respectively. Seven patients died, for a 2.3% early mortality. Permanent neurologic dysfunction developed in 5 patients (1.6%), and temporary neurologic dysfunction in 20 (6.6%). The mid-term survival rate was 94.6% +/- 1.5% at 3 years. On multivariate analyses, prolonged surgery was a risk factor for early mortality. Preoperative cerebral hypoperfusion was a significant determinant for temporary neurologic dysfunction and male gender for permanent neurologic dysfunction.

CONCLUSIONS

Integrated total arch replacement using antegrade selective cerebral perfusion with right axillary artery cannulation yields a favorable outcome with low mortality and cerebral morbidity rates.

Prevention of Ischemic Neurologic Injury With Intraoperative Monitoring of Selected Cardiovascular and Cerebrovascular Procedures: Roles of Electroencephalography, Somatosensory Evoked Potentials, Transcranial Doppler, and Near-Infrared Spectroscopy

All neuromonitoring techniques, although imperfect, provide useful information for monitoring cardiothoracic and carotid vascular operations. They may be viewed as providing complementary information, which may help surgical technique and, as a result, possibly improve clinical outcomes. As of this writing, the efficacy of TCD and NIRS monitoring during cardiothoracic and vascular surgery cannot be considered established. Well designed, prospective, adequately powered, double-blind, and randomized outcome studies are needed to determine the optimal neurologic monitoring modality (or modalities), in specific surgical settings.

Aortic Arch Reconstruction: Safety of Moderate Hypothermia and Antegrade Cerebral Perfusion During Systemic Circulatory Arrest

BACKGROUND AND AIM

The ideal strategy for cerebral protection during aortic arch (AA) reconstructive surgery remains undefined. Antegrade cerebral perfusion (ACP) during systemic circulatory arrest (SCA) may provide superior results; however, optimal systemic temperature is undetermined. Our objective was to determine whether "deep" hypothermia is necessary during ACP with SCA, and whether the degree of hypothermia is associated with neurologic outcomes postoperatively.

METHODS

Retrospective series of 72 consecutive patients (aged 65.9 +/- 3.2 years) who underwent AA reconstructive surgery at Vancouver General Hospital using a cerebral protection strategy of ACP with SCA between December 1995 and December 2002. Patients were divided into two groups according to lowest systemic temperature: <22 degrees C (n = 52) and > or =22 degrees C (n = 20).

RESULTS

ACP was via right axillary or innominate artery, +/- left common carotid cannulation. Median SCA time with ACP was not different between groups. There were four hospital deaths (5.6%) (three from the <22 degrees C group). Eight patients (11.2%) had major neurologic injuries (seven from the <22 degrees C group): 4 (5.6%) permanent (1 fatal) and 4 (5.6%) temporary. There was a trend toward a significantly higher incidence of delirium in the <22 degrees C group than the > or =22 degrees C group (30.8 vs 10.0%, respectively, p = 0.07).

CONCLUSIONS

In our experience, SCA with ACP was a safe technique for AA reconstructive surgery. The observation of a larger number of major neurologic injuries, and a trend toward a higher incidence of delirium in the <22 degrees C group, suggests that systemic temperatures below 22 degrees C may not be necessary and may be associated with a higher incidence of neurologic injury when using ACP during SCA.

Perioperative Outcome in Adults Undergoing Elective Deep Hypothermic Circulatory Arrest With Retrograde Cerebral Perfusion in Proximal Aortic Arch Repair: Evaluation of Protocol-Based Care

OBJECTIVE

The purpose of this study was to describe perioperative outcome in adults undergoing elective proximal aortic arch repair with protocol-based deep hypothermic circulatory arrest (DHCA) with retrograde cerebral perfusion (RCP).

DESIGN

Retrospective and observational.

SETTING

Cardiothoracic operating rooms and intensive care unit.

PARTICIPANTS

Seventy-nine consecutive adults undergoing elective proximal aortic arch repair with DHCA (1999-2001).

INTERVENTIONS

None.

MAIN RESULTS

Average age of the patients was 64.9 years. Mean circulatory arrest time was 30.4 +/- 8.5 minutes. Perioperative mortality was 7.6%. Perioperative stroke incidence was 3.8%. Tracheal extubation was successful in 87.3% of patients within 24 hours of operation. Of the cohort, 80.8% were discharged from the intensive care unit within 72 hours of surgery. Median length of hospital stay was 7.4 days. Repeat mediastinal exploration because of bleeding occurred in 3.8% of patients. Although perioperative renal dysfunction (defined as >1.5-fold increase in plasma creatinine concentration) developed in 24.0% of patients, only 3.8% required dialysis.

CONCLUSIONS

The above parameters establish a baseline incidence for major perioperative complications in adults undergoing elective DHCA with RCP for elective proximal aortic arch repair. In approaching the open aortic arch for short periods of circulatory arrest, deep hypothermia with adjunctive RCP is safe and effective.

Influence of Cardiopulmonary Bypass on the State of Cognitive Functions in Patients with Ischemic Heart Disease

Forty patients with ischemic heart disease and undergoing aortocoronary shunting surgery with cardiopulmonary bypass were studied. All patients were subjected to neuropsychological assessment and immunochemical analysis of the production of chemokines (IL-8, IP-10, MCP-1, MCP-3, MIP-1 beta, SDF-1 alpha) and cytokines (TNF-alpha and IL-10). The aims of the study were to assess the presence and severity of cognitive deficit developing after surgery with cardiopulmonary bypass and to assess the effects of intraoperative Trasylol on its severity. Cognitive deficit on day 9 after coronary shunting with cardiopulmonary bypass was seen as impairments of attention, hearing-speech memory, visual memory, and dynamic praxis. Trasylol had a marked neuroprotective effect and suppressed the systemic inflammatory response. Patients given intraoperative Trasylol had no clinically significant cognitive deficit in the early post-operative period.

Clinical Predictors for Prolonged Intensive Care Unit Stay in Adults Undergoing Thoracic Aortic Surgery Requiring Deep Hypothermic Circulatory Arrest

OBJECTIVE

The purpose of this study was to describe clinical predictors for prolonged length of stay in the intensive care unit (PLOS-ICU) after adult thoracic aortic surgery requiring standardized deep hypothermic circulatory arrest (DHCA); and to determine the incidence of PLOS-ICU after DHCA, univariate predictors for PLOS-ICU, and multivariate predictors for PLOS-ICU.

STUDY DESIGN

A retrospective and observational study. PLOS-ICU was defined as longer than 5 days in the ICU.

STUDY SETTING

Cardiothoracic operating rooms and the ICU.

PARTICIPANTS

All adults requiring thoracic aortic repair with DHCA INTERVENTIONS: None.

MAIN RESULTS

The cohort size was 144. The incidence of PLOS-ICU was 27.8%. The mortality rate was 11.1%. Univariate predictors for PLOS-ICU were age, stroke, DHCA duration, vasopressor dependence >72 hours, mediastinal re-exploration for bleeding, and renal dysfunction. Multivariate predictors for PLOS-ICU were stroke, vasopressor dependence >72 hours, and renal dysfunction.

CONCLUSIONS

PLOS-ICU after DHCA is common. The identified multivariate predictors merit further hypothesis-driven research to enhance perioperative protection of the brain, kidney, and cardiovascular system.

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.

Major Clinical Outcomes in Adults Undergoing Thoracic Aortic Surgery Requiring Deep Hypothermic Circulatory Arrest: Quantification of Organ-Based Perioperative Outcome and Detection of Opportunities for Perioperative Intervention

OBJECTIVE

The purpose of this study was to describe clinical outcome after adult thoracic aortic surgery requiring standardized deep hypothermic circulatory arrest (DHCA), to determine mortality and length of stay, neurologic outcome, cardiorespiratory outcome, and hemostatic and renal outcome after DHCA.

DESIGN

Retrospective and observational.

SETTING

Cardiothoracic operating rooms and intensive care unit (ICU).

PARTICIPANTS

All adults requiring thoracic aortic repair with DHCA.

INTERVENTIONS

None. The study was observational.

MAIN RESULTS

The cohort size was 110. All patients received an antifibrinolytic. The mortality rate was 8.2%. The mean length of stay was 6.8 days (ICU) and 14.0 days (hospital). The incidence of stroke was 8.1% and postoperative delirium was 10.9%. The rate of postoperative atrial fibrillation was 43.6%; 19.1% required postoperative mechanical ventilation longer than 72 hours. Chest tube drainage was 931 mL for the first 24 hours. Postoperative dialysis was required in 1.8% of patients. Renal dysfunction occurred in 40% to 50% of patients, depending on the definition.

CONCLUSIONS

The protocol for DHCA at the authors' institution is associated with superior or equivalent perioperative outcomes to those reported in the literature. This study identified the need for further quantification of the clinical outcomes after DHCA in order to prioritize outcome-based hypothesis-driven prospective intervention in DHCA.

Optimal temperature for selective cerebral perfusion

OBJECTIVE

Although combinations of hypothermic circulatory arrest and antegrade selective cerebral perfusion are used for cerebral protection during arch surgery, there is no consensus regarding the optimal temperature during selective cerebral perfusion. This study explored the effect of different temperatures during selective cerebral perfusion on cerebral metabolism and neurologic outcome.

METHODS

In this blinded study, 40 pigs (19-21 kg) were randomized into 4 groups after 30 minutes of hypothermic circulatory arrest at 20 degrees C. During a 60-minute interval of selective cerebral perfusion, with flow regulated to maintain a perfusion pressure of 50 mm Hg, pigs were perfused at 10 degrees C, 15 degrees C, 20 degrees C, and 25 degrees C. Fluorescent microspheres enabled calculation of cerebral blood flow during perfusion and recovery. Hemodynamics, intracranial pressure, cerebrovascular resistance, and oxygen consumption were also monitored. Behavioral scores were obtained for 7 days after surgery.

RESULTS

Cerebral blood flow decreased significantly ( P < .002) during cooling in all groups: it was significantly higher throughout selective cerebral perfusion in the 20 degrees C to 25 degrees C versus the 10 degrees C to 15 degrees C group ( P = .0001) and remained higher during recovery ( P = .0001). Oxygen consumption decreased significantly with cooling ( P = .0001), remained low during perfusion, and rebounded with rewarming but was significantly lower at 10 degrees C to 15 degrees C than at 20 degrees C to 25 degrees C throughout selective cerebral perfusion ( P = .003) and after CPB was discontinued ( P = .001). Postoperative behavioral scores were significantly better after selective cerebral perfusion at 10 degrees C to 15 degrees C than at 20 degrees C to 25 degrees C ( P = .001).

CONCLUSIONS

This study suggests that selective cerebral perfusion at 10 degrees C to 15 degrees C provides better cerebral protection than selective cerebral perfusion at 20 degrees C to 25 degrees C, even though oxygen consumption remains low for hours after selective cerebral perfusion at 10 degrees C to 15 degrees C. Prompt return of metabolism to baseline levels after hypothermic circulatory arrest/selective cerebral perfusion does not necessarily predict superior behavioral outcome.

Use of a Maze to Detect Cognitive Dysfunction in a Porcine Model of Hypothermic Circulatory Arrest

BACKGROUND

Hypothermic circulatory arrest (HCA) can result in cognitive impairment not reflected by histopathology or gross neurologic observation. We tested the sensitivity of two multi-room maze tasks in detecting cerebral dysfunction after HCA in pigs.

METHODS

Twenty-seven pigs were studied, divided between two tasks. 13 underwent 90 minutes HCA at 20 degrees C and were trained from postoperative day (POD) 7; 14 were unoperated controls. The maze includes a holding area, 8 rooms, and a center hallway. One piece of apple is placed in each baited room on each of 10 days of learning evaluation. After a pig enters a room, doors to all other rooms close, and the pig must return to the holding area. In task 1, 6 of 8 rooms were baited, and each day's session ended when each baited room had been entered, or after 20 trials. In task 2, initially only the right- or left-sided rooms were baited. Pigs were evaluated each day until they entered 4 baited rooms, or for 15 trials; the process was then repeated, baiting the other side.

RESULTS

Intraoperative physiology and postoperative recovery showed no differences between task 1 or 2 pigs. Task 1 did not distinguish between control and HCA groups (p = 0.5), but task 2 revealed significantly (p = 0.04) better learning in controls.

CONCLUSIONS

The significantly poorer performance of pigs after HCA suggests that the reversal of baited rooms in task 2 provides the sensitivity to detect cognitive dysfunction. The maze is a promising tool to investigate in pigs the mild cerebral damage often seen after HCA.

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.

Single-stage repair of extensive thoracic aortic aneurysms: Experience with the arch-first technique and bilateral anterior thoracotomy

BACKGROUND

Staged procedures for extensive aneurysmal disease of the thoracic aorta are associated with a substantial cumulative mortality (>20%) that includes hospital mortality for the 2 procedures and death (often from aortic rupture) in the interval between the 2 procedures. We have used a single-stage technique for operative repair of most or all of the thoracic aorta.

METHODS

Forty-six patients with extensive disease of the thoracic aorta were managed with a single-stage procedure by using a bilateral anterior thoracotomy and transverse sternotomy, hypothermic circulatory arrest, and reperfusion of the aortic arch vessels first to minimize brain ischemia. Thirty-one patients with chronic, expanding type A aortic dissections had previous operations for acute type A dissection (n = 22), aortic valve repair or replacement (n = 4), coronary artery bypass grafting (n = 4), or no previous operation (n = 1). The remaining 15 patients had degenerative aneurysms (n = 12) or chronic type B dissections with proximal extension (n = 3). The ascending aorta and aortic arch were replaced in all patients combined with resection of various lengths of descending aorta (proximal one third [n = 19], proximal two thirds to three quarters [n = 22], or all [n = 5]). Coronary artery bypass grafting, valve replacement, or both were performed concomitantly in 19 patients.

RESULTS

Hospital mortality was 6.5% (3 patients). Morbidity included reoperation for bleeding (17%), mechanical ventilation for more than 72 hours (42%), temporary tracheostomy (13%), and temporary renal dialysis (9%). No patient sustained a stroke. There have been 5 late deaths (3, 18, 34, 51, and 79 months postoperatively) unrelated to the aortic disease. Four patients have undergone successful reoperation on the aorta (false aneurysm [n = 1], endocarditis [n = 1], and progression of disease [n = 2]). Five-year survival was 75%.

CONCLUSION

The single-stage, arch-first technique is a safe and suitable alternative to the 2-stage procedure for repair of extensive thoracic aortic disease.

Tau protein in the cerebrospinal fluid is a marker of brain injury after aortic surgery

BACKGROUND

Tau is a protein localized primarily in neurons, especially in the axonal compartment. Cerebrospinal fluid tau levels are elevated in acute stroke and head traumas. The purpose of this study is to elucidate the alterations of cerebrospinal fluid tau levels in patients with or without neurologic complication after aortic surgery.

METHODS

Twenty-eight patients undergoing descending thoracic (n = 8) or thoracoabdominal (n = 20) aortic surgery were enrolled. Cerebrospinal fluid tau levels were measured before operation and at seven time points up to the 72nd postoperative hour, and were compared with cerebrospinal fluid S100B levels.

RESULTS

Two patients developed brain infarction, including the one with paraplegia. In these patients, 20-fold to 100-fold tau elevation was observed, but S100B elevation was less evident in the patient without paraplegia. Three other patients developed spinal cord injury. Additional three patients suffered from temporary neurologic dysfunction of the brain. Tau levels in the latter three patients showed tenfold elevation and were higher than those in the three patients with spinal cord injury or those in the patients without neurologic complication up to 24 postoperative hours. The S100B levels were also higher in the three patients with temporary neurologic dysfunction of the brain than in the patients without neurologic complication at the conclusion of surgery. From 6 to 24 postoperative hours, they were higher in the three patients with spinal cord injury than in the patients without neurologic complication.

CONCLUSIONS

These preliminary results suggest that cerebrospinal fluid tau levels reflect brain injury. Because tau levels may separate the patients with temporary neurologic dysfunction, they may serve as a useful marker of brain injury.

Pravastatin, a 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor, reduces delayed neuronal death following transient forebrain ischemia in the adult rat hippocampus

Recent evidence indicates that statins have beneficial effects on the brain in the ischemic condition. However, there is a lack of studies related to the effect of statins on delayed neuronal death. We investigated the effect of prophylactic therapy with pravastatin on delayed neuronal death in the rat hippocampus. The rats were given a daily dose of 20 mg/kg of pravastatin orally for 14 days. Transient forebrain ischemia was induced by the four-vessel occlusion method. Three days after ischemia, surviving neurons of the hippocampal CA1 subfield were counted. Our results demonstrated that prophylactic statin treatment significantly reduced delayed neuronal death after transient forebrain ischemia. Our findings suggest that prophylactic statin treatment may be useful in preventing functional neurological disorders after transient cerebral ischemic insult.

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.

Technical advances in total aortic arch replacement

BACKGROUND

We compared the effects of using hypothermic circulatory arrest (HCA) alone, HCA combined with selective cerebral perfusion (SCP), and use of SCP with a trifurcated graft (T) on outcome after aortic arch repair.

METHODS

One hundred fifty patients, median age 66 years (range, 27 to 85), underwent total arch replacement between 1988 and 2002; 75 were female. We retrospectively compared the results of three patient groups roughly comparable with regard to preoperative risk factors: 45 patients using HCA beginning in 1988; 67 patients using HCA/SCP beginning in 1994; and 38 patients utilizing a trifurcated arch graft in conjunction with SCP through the axillary artery (HCA/SCP/T) since 2000. The groups were well matched with regard to median age (66, 68, and 66 years), urgency (emergent 11%, 13%, 5%; urgent 24%, 9%, 18%; and elective 64%, 78%, 76%), and several other known risk factors (p = not significant).

RESULTS

An adverse outcome-hospital death or permanent stroke-occurred in 14%: in 16% with HCA, in 16% with HCA/SCP, and in 8% with HCA/SCP/T. Transient neurologic dysfunction among patients surviving without stroke was lower with HCA/SCP/T (11%) than with HCA (33%) or HCA/SCP (17%). Mean duration of HCA was 52 +/- 16 minutes with HCA alone versus 45 +/- 10 minutes with HCA/SCP and 31 +/- 7 minutes with HCA/SCP/T (p < 0.0001 for groups HCA and HCA/SCP combined versus HCA/SCP/T). Mean duration of SCP was 57 +/- 25 minutes with HCA/SCP versus 62 +/- 24 minutes with HCA/SCP/T (p = not significant). Comparison of the groups of patients who had comparable preoperative risk factors for adverse outcome showed a trend toward lower adverse outcome and transient neurologic dysfunction rates using HCA/SCP/T; a significant reduction in respiratory (p < 0.001), infectious (p = 0.015) and cardiac (p = 0.005) complications in HCA/SCP/T compared with the earlier groups; and significantly shorter durations of intensive care (p < 0.0001) and hospitalization (p = 0.004).

CONCLUSIONS

Our results suggest that HCA/SCP is superior to HCA alone for preventing cerebral injury during operations on the aortic arch. By further reducing embolic risk as well as duration of HCA, HCA/SCP/T with axillary artery cannulation may be the optimal technique for averting adverse outcomes, reducing complications, and shortening hospital stay after aortic arch repair.

Cerebral physiology and outcome after hypothermic circulatory arrest followed by selective cerebral perfusion

BACKGROUND

This study explored the impact of an interval of hypothermic circulatory arrest (HCA) preceding selective cerebral perfusion (SCP) on cerebral physiology and outcome. This protocol allows use of SCP during aortic surgery without the threat of embolization inherent in balloon catheterization of often severely atherosclerotic cerebral vessels.

METHODS

In this blinded study, 30 pigs (20 to 22 kg) were randomized after cooling to 20 degrees C. Pigs in the HCA-CPB group (n = 10) underwent 30 minutes of HCA followed by 60 minutes of total body perfusion (CPB); HCA-SCP pigs (n = 10) underwent 30 minutes of HCA followed by 60 minutes of SCP, and SCP pigs (n = 10) had 90 minutes of SCP without prior HCA. Fluorescent microspheres enabled calculation of cerebral blood flow during perfusion and recovery. Hemodynamics, intracranial pressure, cerebrovascular resistance, and cerebral oxygen consumption were also monitored. Daily behavioral scores were obtained for 7 days postoperatively.

RESULTS

In all groups, cerebral oxygen consumption fell significantly with cooling (p < 0.0001), remained low during perfusion, and rebounded promptly with rewarming; cerebral oxygen consumption was significantly (p = 0.027) greater during SCP than during HCA-CPB. Cerebral blood flow was significantly higher throughout SCP in the HCA-SCP group (p < 0.0001) than with CPB. Cerebrovascular resistance during SCP and HCA-SCP was significantly lower (p = 0.036) than during CPB. Behavioral scores were significantly better with SCP than with HCA-CPB throughout recovery, but did not differ between SCP and HCA-SCP.

CONCLUSIONS

This study suggests that a short period of HCA preceding SCP provides global cerebral protection comparable to continuous SCP, implying that in clinical practice, a short period of HCA to reduce risk of embolization will not compromise the superior cerebral protection provided by SCP.

Total aortic arch grafting via median sternotomy using integrated antegrade cerebral perfusion

BACKGROUND

In aortic arch grafting, antegrade cerebral perfusion prolongs the safe time of arch exclusion. However, there are the problems of cerebral embolism and distribution of the cerebral perfusion. We describe and analyze mortality and cerebral complications in patients undergoing total arch grafting using our refined technique.

METHODS

Between June 1994 and March 2002, 100 consecutive patients underwent total arch grafting through median sternotomy. There were 49 atherosclerotic aneurysms and 51 aortic dissections. Fifty-four patients were operated on an emergency basis because of rupture or acute type A dissection. We conducted total arch grafting using hypothermic antegrade cerebral perfusion from every cervical vessel. Carbon dioxide gas was added to the cerebral perfusion in order to inhibit the increase in the cerebral vascular resistance during hypothermic cerebral perfusion.

RESULTS

Hospital mortality was 4%. The causes of death were dysarrhythmia (n = 1), mesenteric necrosis (n = 1), and preoperative cardiac arrest (n = 2). On univariate analysis, preoperative shock and concomitant cardiac procedures were risk factors for hospital death. The rate of postoperative neurologic damage was 5%. Two patients suffered from cerebral infarction. Temporary neurologic dysfunction occurred in 3 patients. On univariate analysis, emergency surgery was a risk factor for postoperative neurologic damage. On multivariate analysis, there was no significant independent predictor of hospital mortality and neurologic damage. Actuarial survival at 96 months was 66.4 +/- 9.1%, and freedom from aortic accidents (reoperation, rupture, and cholesterol embolism) was 74.9 +/- 7.9%.

CONCLUSIONS

The early- and long-term results of total arch grafting using integrated antegrade cerebral perfusion were found to be satisfactory.

Risk factors of mortality and permanent neurologic injury in patients undergoing ascending aortic and arch repair

OBJECTIVES

To analyze outcome in elderly patients after surgical repair of the ascending aorta and the aortic arch as compared with their younger counterparts and to determine risk factors of mortality and permanent neurologic injury. Patients and methods Between January 1995 and February 2003, a total of 369 patients underwent ascending aortic and arch repair. Indications for surgical intervention were acute type A dissections in 174 (47%) patients (<75 years, n = 147; > or =75 years, n = 27) and chronic atherosclerotic aneurysms in 195 (53%) patients (<75 years, n = 168; > or =75 years, n = 27). Emergency surgery was performed in 167 (45%) patients; 202 patients (54.7%) underwent surgery requiring deep hypothermic circulatory arrest. Pre- and intraoperative factors were evaluated by means of stepwise logistic regression analysis to determine risk factors of mortality and permanent neurologic injury.

RESULTS

Overall in-hospital mortality was 11.6%. In-hospital mortality with regard to indication for surgical intervention was comparable in both age groups (type A dissection: <75 years, 15.6%; > or =75 years, 18.5%; P =.731; chronic atherosclerotic aneurysm: <75 years, 7.7%; > or =75 years, 7.4%; P =.933). Permanent neurologic injury was observed in 5.0%. Permanent neurologic injury with regard to surgical intervention was comparable in both age groups (type A dissection: <75 years, 8.8%; > or =75 years, 3.7%; P =.359; chronic atherosclerotic aneurysm: <75 years, 3.0%; > or =75 years, 3.7%; P =.843). Stepwise logistic regression analysis revealed preoperative hemodynamic instability (odds ratio 4.3; P =.000), duration of cardiopulmonary bypass (odds ratio 2.1; P =.001), and permanent neurologic injury (odds ratio 1.7; P =.033) but not age as independent predictors affecting mortality. Utilization of but not duration of deep hypothermic circulatory arrest was the only independent predictor of permanent neurologic injury (odds ratio 2.8; P =.019).

CONCLUSIONS

Age shows a trend toward a higher risk of mortality but does not predict a higher incidence of permanent neurologic injury after ascending aortic and arch repair. As utilization of deep hypothermic circulatory arrest remains the only independent predictor of permanent neurologic injury, alternative approaches to maintain cerebral perfusion during ascending aortic and arch repair are warranted.

Diabetes and evidence of atherosclerosis are major risk factors for adverse outcome after elective thoracic aortic surgery

BACKGROUND

To predict risk after elective repair of ascending aorta and aortic arch aneurysms, we studied 464 consecutive patients.

METHODS

Adverse outcome (stroke or hospital death) was analyzed in 372 patients who underwent proximal repair and 92 patients who underwent aortic arch replacement from 1986 to the present. Preoperative risk factors with a P value less than.2 in a univariate analysis were entered into a multivariate model, and an equation incorporating independent risk factors was derived separately for proximal aorta and arch surgery.

RESULTS

Age more than 65 years (P =.04), diabetes (P =.02), cause (P =.01), and prolonged total cerebral protection time (duration of hypothermic circulatory arrest and selective cerebral perfusion, P =.001) were significant univariate risk factors for elective proximal aortic repair. Diabetes (P =.005, odds ratio 5.1), atherosclerosis (P =.003, odds ratio 4.0), and dissection (P =.048, odds ratio 2.5) were independent factors. For elective arch surgery, female sex (P =.07), age more than 65 years (P =.04), coronary artery disease (P =.02), diabetes (P =.06), cause (P =.07), and prolonged total cerebral protection time (P =.025) were univariate risk factors. Female sex (P =.05, odds ratio 4.7), coronary artery disease (P =.02, odds ratio 6.5), diabetes (P =.13, odds ratio 4.0), and total cerebral protection time (P =.03, odds ratio 1.02/min) were independent factors. To calculate risk of adverse outcome (P), enter 1 if factor is present, 0 if absent, and estimate total cerebral protection time (in minutes). [equation: see text].

CONCLUSION

In this large series of patients, the presence of diabetes and manifestations of atherosclerosis emerge as extremely important risk factors for adverse outcome after ascending aorta or arch surgery, displacing age. Multivariate equations derived from these data allow more precise calculation of risk for each individual contemplating elective surgery.

The incidence of transient neurologic dysfunction after ascending aortic replacement with circulatory arrest

BACKGROUND

Transient neurologic dysfunction (TND) namely postoperative confusion, delirium, and agitation after aortic operation, particularly after deep hypothermic circulatory arrest (DHCA), remains an underestimated adverse event in the early outcome of these patients. Although no influence on long-term outcome has been reported so far, this entity markedly affects the early outcome and leads to prolonged intensive care unit and hospital stay.

METHODS

Between January 1997 and January 2003, 160 consecutive patients (130 type A dissections [81%] and 30 elective atherosclerotic aneurysms [19%]) had surgical repair with DHCA for a thoracic aortic aneurysm limited to the ascending aorta. From those, 40 patients (25%) underwent DHCA alone, whereas in 13 patients (8%) antegrade cerebral perfusion and in 103 patients (64%) retrograde cerebral perfusion was used for further brain protection.

RESULTS

The overall incidence of TND was 18% (28 of 160) with a significant association between duration of circulatory arrest and the incidence of TND (13.8% in DHCA < 30 minutes versus 37.9% in DHCA > 40 minutes; p < 0.05). Furthermore the severity of TND was directly associated with the duration of circulatory arrest and age. In contrast, however, the use of retrograde cerebral perfusion had no influence on the incidence of TND, (p < 0.05). Intensive care unit stay as well as hospital stay were prolonged in the patients with TND (intensive care unit 14.3 +/- 14.2 days versus 10.8 +/- 13.7 days, p < 0.05; hospital stay 15.6 +/- 10.1 days versus 11.4 +/- 7.9 days, p < 0.05).

CONCLUSIONS

Duration of DHCA, regardless of whether retrograde cerebral perfusion was used, was the most important predictor of the incidence of transient neurologic dysfunction in patients who had replacement of the ascending thoracic aorta. The occurrence of TND leads to impaired functional recovery as well as prolonged intensive care unit and hospital stay.

Brain protection using antegrade selective cerebral perfusion: a multicenter study

BACKGROUND

To evaluate the results of antegrade selective cerebral perfusion as a method of brain protection during surgery of the thoracic aorta and to determine predictors of hospital mortality and adverse neurologic outcome.

METHODS

Between October 1995 and March 2002, 588 patients underwent aortic surgery with the aid of antegrade selective cerebral perfusion. There were 334 men (56.8%); the mean age was 63.7 +/- 11.8 years. One hundred sixty-two patients (27.6%) underwent urgent operation. The separated graft technique was employed to reimplant the arch vessels in 230 patients (65.3%) of the 352 requiring aortic arch replacement. Associated procedures were performed in 254 patients (43.2%). One hundred twelve patients underwent elephant trunk procedure. The mean cerebral perfusion time was 67 +/- 37 minutes.

RESULTS

The overall hospital mortality rate was 8.7%. A logistic regression analysis revealed urgent operation, recent central neurologic event, tamponade, unplanned coronary artery revascularization and pump time to be independent predictors of hospital mortality (p < 0.05). The permanent neurologic dysfunction rate was 3.8%. A logistic regression analysis showed tamponade to be independent predictor of permanent neurologic dysfunction (p < 0.05). The transient neurologic dysfunction rate was 5.6%. Recent central neurologic event, tamponade, coronary disease, and aortic valve replacement were indicated as independent predictors of transient neurologic dysfunction by logistic regression (p < 0.05).

CONCLUSIONS

In our experience the utilization of antegrade selective cerebral perfusion resulted in encouraging results in terms of hospital mortality and brain complications. Neither the extent of the replacement nor the duration of the cerebral perfusion had an impact on hospital mortality and neurologic outcome.

Predictors of adverse outcome and transient neurological dysfunction following surgical treatment of acute type A dissections

Predictors of adverse outcome after replacement of the ascending aorta with resection of the intimal tear and open distal anastomosis were analyzed in 167 patients (109 male, median age 56). Median hypothermic circulatory arrest (HCA) time was 30 minutes (range 12 to 113). Eighty-six patients (pts) had surgery within 24 hours and 81 within 72 hours of symptom onset. Thirty-seven pts had only ascending aortic replacement, 128 had hemiarch repair, and in 2 the entire arch was replaced. The aortic valve was replaced in 37 pts, resuspended in 116, and untouched in 14. Either death or permanent neurological dysfunction was considered an adverse outcome (AO). AO occurred in 30.5% (51/167) of patients overall. Multivariate analysis revealed that the only significant (P<0.05) independent preoperative predictor of AO was hemodynamic instability (OR 6.0). Transient neurological dysfunction (TND) occurred in 19 of 116 patients (16.4%). Significant predictors of TND were increasing age >60 (OR 3.4 and 7.0 in the second and third tertile as compared with the lowest tertile) and coronary heart disease (OR 3.4). Cumulative survival of patients (median follow-up 34 months) was 55% at 1, 49% at 5, and 44% at 8 years, indicating an excessive in-hospital mortality, but excellent long term outcome. Surgical treatment of acute type A dissections is still associated with a high incidence of adverse outcome, but results in excellent long-term survival. Earlier diagnosis, before the development of cardiac tamponade and hemodynamic compromise, is critical to improve the operative salvage rate.

Neuropsychometric outcome following aortic arch surgery: a prospective randomized trial of retrograde cerebral perfusion

BACKGROUND

Aortic surgery requiring hypothermic circulatory arrest is associated with a high incidence of brain injury. However, knowledge of neuropsychometric outcome is limited. Retrograde cerebral perfusion has become a popular adjunctive technique to hypothermic circulatory arrest. The aim of this study was to assess neuropsychometric outcome and compare the 2 techniques.

METHODS

In a prospective randomized trial, 38 patients requiring elective aortic arch surgery were allocated to either hypothermic circulatory arrest plus retrograde cerebral perfusion or hypothermic circulatory arrest alone. Neuropsychometric testing was performed preoperatively, and at 6 weeks and 12 to 24 weeks postoperatively. Deficit was defined as a 20% decline in 2 tests or more. Standardized Z scores were calculated for each patient and test. Eighteen patients underwent hypothermic circulatory arrest and 20 patients underwent hypothermic circulatory arrest plus retrograde cerebral perfusion. The mean cardiopulmonary bypass, hypothermic circulatory arrest, and retrograde cerebral perfusion durations were 169, 30, and 25 minutes, respectively.

RESULTS

There were 2 deaths and 2 neurological deficits. At 6 weeks postoperatively, 77% of the hypothermic circulatory arrest group and 93% of the hypothermic circulatory arrest plus retrograde cerebral perfusion group had a deficit (P =.22). At 12 weeks this was reduced to 55% and 56%, respectively (P =.93). There was a worse total Z test score in the hypothermic circulatory arrest plus retrograde cerebral perfusion group at 12 weeks (P =.05). Neuropsychometric change did not correlate with hypothermic circulatory arrest duration, presence of aortic atheroma, cannulation technique, or procedure.

CONCLUSIONS

Hypothermic circulatory arrest plus/minus retrograde cerebral perfusion is associated with a high incidence of neuropsychometric change despite ostensibly normal clinical outcomes and apparently safe arrest duration. Retrograde cerebral perfusion did not improve outcome in this small study.

Deep hypothermic circulatory arrest and antegrade selective cerebral perfusion during ascending aorta-hemiarch replacement: a retrospective comparative study

OBJECTIVE

We sought to compare the results of ascending aorta-hemiarch replacement by using 2 different methods of cerebral protection in terms of hospital mortality, neurologic outcome, and systemic morbidity and to determine predictive risk factors associated with hospital mortality and neurologic outcome after ascending aorta-hemiarch replacement.

METHODS

Between January 1995 and September 2001, 289 patients (mean age, 62.2 +/- 13.2 years; urgent status, 122/289 [42.2%]) underwent ascending aorta-hemiarch replacement with the aid of antegrade selective cerebral perfusion (161 patients) or deep hypothermic circulatory arrest (128 patients).

RESULTS

Overall hospital mortality was 11.4% (deep hypothermic circulatory arrest group, 13.3%; antegrade selective cerebral perfusion group, 9.9%; P =.375). A logistic regression analysis revealed acute type A dissection (P =.001; odds ratio, 4.3) and age of greater than 70 years (P =.019; odds ratio, 2.5) to be independent predictors of hospital mortality. The permanent neurologic dysfunction rate was 9.3% (deep hypothermic circulatory arrest group, 12.5%; antegrade selective cerebral perfusion group, 7.6%; P =.075). Logistic regression analysis revealed acute type A dissection (P =.001; odds ratio, 6.7) and history of cerebral infarction-transient ischemic attack (P =.038; odds ratio, 3.4) to be independent predictors of permanent neurologic dysfunction. The transient neurologic dysfunction rate was 8.0% (deep hypothermic circulatory arrest group, 7.1%; antegrade selective cerebral perfusion group, 8.7%; P =.530). Acute type A dissection (P =.001; odds ratio, 5.1) was indicated as an independent predictor of transient neurologic dysfunction by means of logistic regression. Renal dysfunction (postoperative creatinine level of >250 micromol/L; deep hypothermic circulatory arrest, 10 [7.8%]; antegrade selective cerebral perfusion, 6 [3.7%]; P =.030), as well as prolonged intubation time (deep hypothermic circulatory arrest, 3.8 +/- 6.3 days; antegrade selective cerebral perfusion, 2.2 +/- 2.5 days; P =.005) were more common in the deep hypothermic circulatory arrest group.

CONCLUSION

The use of antegrade selective cerebral perfusion and deep hypothermic circulatory arrest during ascending aorta-hemiarch replacement resulted in acceptable hospital mortality and neurologic outcome. Reduced postoperative intubation time and better renal function preservation were observed in the antegrade selective cerebral perfusion group.

Antegrade selective cerebral perfusion during operations on the thoracic aorta: factors influencing survival and neurologic outcome in 413 patients

OBJECTIVE

We retrospectively analyzed hospital mortality and neurologic outcome after operations on the thoracic aorta with the aid of antegrade selective cerebral perfusion to determine a predictive risk model.

METHODS

Between October 1995 and May 2001, 413 patients (mean age, 63.0 +/- 11.5 years) underwent operations on the thoracic aorta with antegrade selective cerebral perfusion. Indications for surgical intervention were acute type A dissection in 116 (28.1%) patients, degenerative aneurysm in 227 (55.0%) patients, and postdissection aneurysm in 70 (16.9%) patients. One hundred twenty-five (30.3%) patients were operated on urgently; concomitant procedures were performed in 171 (41.4%) patients. Mean cerebral perfusion time was 63.0 +/- 38.7 minutes (range, 16-220 minutes). Preoperative and intraoperative factors were evaluated by means of univariate and multivariate analysis to identify predictors of hospital mortality and neurologic outcome.

RESULTS

The hospital mortality was 9.4%. Stepwise logistic regression revealed urgency status (P =.000; odds ratio, 19.9) and recent history of a recent central neurologic event (P =.004; odds ratio, 8.0) to be independent determinants for hospital mortality. Temporary neurologic dysfunction occurred in 20 (5.1%) patients. Urgency status (P =.005; odds ratio, 7.5), history of a central neurologic event (P =.003; odds ratio, 8.6), and coronary artery bypass grafting (P =.019; odds ratio, 6.0) were independent determinants of temporary neurologic dysfunction. Urgency status (P =.003; odds ratio, 8.6) was the only independent determinant for permanent neurologic dysfunction, and it occurred in 15 (3.7%) patients.

CONCLUSION

Antegrade selective cerebral perfusion is an effective method of brain protection. Cerebral perfusion times of longer than 90 minutes were not associated with an increased risk of hospital mortality or poorer neurologic outcome. Urgency status and recent history of central neurologic events were retained as important risk factors for hospital mortality and neurologic outcome.

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.

Perioperative risk factors for mortality in patients with acute type A aortic dissection

BACKGROUND

This study was undertaken to identify the perioperative risk factors for death in patients with acute type A aortic dissection (AADA).

METHODS

Between 1993 and 2001, 108 consecutive patients (86 men; mean age, 53 years) underwent emergent operations for AADA. All patients but 2 underwent replacement of the ascending aorta with an open distal anastomosis during a period of hypothermic circulatory arrest. In addition, 22 patients had hemiarch and 5 had total arch replacement. Aortic root was replaced in 20 and repaired with gelatin-resorcinol-formaldehyde glue in 39 patients; aortic valve was separately replaced in 3, resuspended in 24, and remained untouched in 22 patients.

RESULTS

Overall in-hospital mortality was 25%. Mortality rate was significantly higher in patients with preoperative dissection complications than in those without (21/36 [58%] vs 6/72 [8%], p < 0.001). In multivariate analysis, predictors of mortality were presence of rupture, renal failure, and intestinal malperfusion, duration of cardiopulmonary bypass > or = 200 minutes, blood loss > or = 500 mL, and transfusion of blood > or = 4 units. Location of the intimal tear, extent of the replacement, type of the aortic root repair, and duration of hypothermic circulatory arrest did not emerge as predictors of mortality.

CONCLUSIONS

Major determinants of surgical mortality in patients with AADA are preoperative complications. Earlier diagnosis remains essential to improve the survival rate.

Single-stage reoperative repair of chronic type A aortic dissection using the arch-first technique

BACKGROUND

Management of the enlarged, chronically dissected aorta after previous repair of acute ascending aortic dissection or after a previous cardiac operation may present a formidable technical challenge and the optimal method of management is not clearly established.

METHODS

Twenty-one patients with chronic type A aortic dissection (mean age 57 years) underwent resection of the ascending aorta, the aortic arch, and varying segments of the descending thoracic aorta. Single-stage replacement with perfusion of the aortic arch first to minimize the duration of brain ischemia and a bilateral anterior thoracotomy (clamshell) incision were used. Fourteen patients had undergone previous repair of acute type A dissection. Seven patients had type A dissection after aortic valve replacement (3 patients) or coronary artery bypass (4 patients). Marked enlargement of the aorta distal to the left subclavian artery precluded a two-stage repair. The mean interval between the initial and reoperative procedures was 69 months (range, 5 to 249).

RESULTS

There was 1 (4.8%) hospital death. Four patients required reoperation for bleeding. One patient required a right ventricular assist device that was successfully removed. Ten patients required assisted ventilation for more than 48 hours. All were successfully weaned from ventilatory support. No patient had a stroke or other adverse neurologic outcome. There has been 1 late death (mean follow-up 2 years).

CONCLUSIONS

The single-stage, arch-first replacement technique is a safe and effective procedure for patients who require extensive reoperations for chronic expanding type A dissection.