Retrograde perfusion and true reverse brain blood flow in humans

Retrograde perfusion through superior vena cava reaches the brain during circulatory arrest

Background

The optimal technique for brain perfusion during circulatory arrest remains controversial. Concern exists that retrograde cerebral perfusion (RCP) via the superior vena cava (SVC) is unable to perfuse the brain. We evaluated whether RCP blood circulates through the brain parenchyma in humans during deep hypothermic circulatory arrest (DHCA). We hypothesized that a significant difference in the levels of S-100β (a protein with very high neuro-sensitivity) between the blood infused in the SVC and the effluent blood returning in the left carotid artery (CA) during RCP, should be regarded as a sign of the circulation of RCP blood through the brain parenchyma.

Methods

We enrolled 10 non-consecutive patients undergoing elective arch-surgery using DHCA and RCP. Circulating S-100β levels were measured at baseline and immediately before DHCA. During DHCA and RCP the difference in S-100β between the SVC and the CA was evaluated after 10 minutes of arrest and immediately before resumption of the circulation. S-100β levels were evaluated using enzyme-linked immunosorbent assay (ELISA).

Results

Mean DHCA duration was 22.4±7.9 minutes. Mean S-100β level at baseline was 92.5±54.9 µg/L. After 10 minutes of DHCA the level of S-100β in the CA was significantly higher than in the SVC (936.9±326.3 vs. 810.9±307.4 µg/L, P=0.0021). This difference was enhanced at the second DHCA sample (1113.8±334.2 vs. 920.5±340.0 µg/L, P=0.0002). There was a statistically significant correlation between the duration of DHCA and the percent difference in S-100β level between the SVC and the CA (Pearson's correlation coefficient =0.902).

Conclusions

RCP is able to perfuse the brain parenchyma in humans during DHCA.

Recommendations for haemodynamic and neurological monitoring in repair of acute type a aortic dissection

During treatment of acute type A aortic dissection there is potential for both pre- and intra-operative malperfusion. There are a number of monitoring strategies that may allow for earlier detection of potentially catastrophic malperfusion (particularly cerebral malperfusion) phenomena available for the anaesthetist and surgeon. This review article sets out to discuss the benefits of the current standard monitoring techniques available as well as desirable/experimental techniques which may serve as adjuncts in the monitoring of these complex patients.

Surgical Approach in Massive Intraoperative Atherosclerotic Embolism

We describe a case of massive embolization of atherosclerotic material during aortic cannulation and the surgical approach chosen to treat it, that is, retrograde cerebral perfusion and subtotal arch replacement in deep hypothermic circulatory arrest.

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.

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.

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.

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.

Failure of retrograde cerebral perfusion to attenuate metabolic changes associated with hypothermic circulatory arrest

OBJECTIVES

Although retrograde cerebral perfusion has become a popular adjunctive technique and may improve cerebral ischemic tolerance during hypothermic circulatory arrest, direct cerebral metabolic benefit has yet to be demonstrated in human subjects. We investigated the post-arrest metabolic phenomena with and without retrograde cerebral perfusion in patients.

METHODS

In a prospective randomized trial, 42 patients undergoing aortic surgery requiring hypothermic circulatory arrest were allocated to receive hypothermic circulatory arrest alone (n = 21) or hypothermic circulatory arrest with additional retrograde cerebral perfusion (n = 21). Circulatory arrest was commenced at 15 degrees C, and retrograde perfusion was instituted through the superior vena cava at a maximum jugular bulb pressure of 25 mm Hg. Transcranial, paired, repeated samples of the arterial and jugular bulb blood were analyzed for oxygen and glucose. Velocity in the right middle cerebral artery was also measured simultaneously.

RESULTS

There were 3 (7.1%) deaths and 3 (7.1%) episodes of neurologic deficit. Mean bypass and circulatory arrest duration (in minutes) were similar between groups (P =.4 and.14). The mean retrograde perfusion duration was 23 minutes. Post-arrest nasopharyngeal temperature was similar (15.3 degrees C vs. 15.3 degrees C). Retrograde perfusion did not affect post-arrest oxygen extraction, glucose extraction, or jugular bulb Po(2). There was no immediate lactate release immediately after hypothermic circulatory arrest.

CONCLUSIONS

Retrograde cerebral perfusion did not influence immediate post-arrest nasopharyngeal temperature or cerebral metabolic recovery. The low jugular bulb Po(2) suggests equivalent ischemia. These findings cast doubt on the effectiveness of retrograde cerebral perfusion as a metabolic adjunct to hypothermic circulatory arrest.

S100beta correlates with neurologic complications after aortic operation using circulatory arrest

BACKGROUND

Astrocyte protein S100beta is a potential serum marker for neurologic injury. The goals of this study were to determine whether elevated serum S100beta correlates with neurologic complications in patients requiring hypothermic circulatory arrest (HCA) during thoracic aortic repair, and to determine the impact of retrograde cerebral perfusion (RCP) on S100beta release in this setting.

METHODS

Thirty-nine consecutive patients underwent thoracic aortic repairs during HCA; RCP was used in 25 patients. Serum S100beta was measured preoperatively, after cardiopulmonary bypass, and 24 hours postoperatively.

RESULTS

Neurologic complications occurred in 3 patients (8%). These patients had higher postbypass S100beta levels (7.17 +/- 1.01 microg/L) than those without neurologic complications (3.63 +/- 2.31 microg/L, p = 0.013). Patients with S100beta levels of 6.0 microg/L or more had a higher incidence of neurologic complications (3 of 7, 43%) compared with those who had levels less than 6.0 microg/L (0 of 30, p = 0.005). Retrograde cerebral perfusion did not affect S100beta release.

CONCLUSIONS

Serum S100beta levels of 6.0 microg/L or higher after HCA correlates with postoperative neurologic complications. Using serum S100beta as a marker for brain injury, RCP does not provide improved cerebral protection over HCA alone.

Increase in serum S100A1-B and S100BB during cardiac surgery arises from extracerebral sources

BACKGROUND

Elevated levels of serum S100B after coronary artery bypass grafting may arise from extracerebral contamination. Serum S100B content was analyzed in several tissues, and the two dimers S100A1-B and S100BB were analyzed separately in blood.

METHODS

Serum, shed blood, marrow, fat, and muscle were studied in patients undergoing coronary artery bypass grafting with cardiopulmonary bypass using suction either to the cardiotomy reservoir (group 1, n = 10) or to a cell-saving device (group 2, n = 10), or operated on off-pump (group 3, n = 10).

RESULTS

Serum S100B was sixfold higher in group 1 than in groups 2 and 3, which were identical. The same ratio between S100A1-B and S100BB was found in all groups. When compared with serum, S100B was 10(2) to 10(4) times higher in marrow, fat, muscle tissue, and shed blood.

CONCLUSIONS

Separate analysis of S100A1-B and S100BB did not distinguish between S100B of cerebral and extracerebral origin. The concept that S100B only originates in astroglial and Schwann cells is wrong. Fat, muscle, and marrow in mediastinal blood contain high levels of S100B. Cardiopulmonary bypass caused no increase in S100B.