Importance of blood pressure regulation in maintaining adequate tissue perfusion during cardiopulmonary bypass.

Patients undergoing surgery with the aid of cardiopulmonary bypass (CPB) have an incidence of end-organ dysfunction, caused by embolization, regional hypoperfusion, or some combination of the two. In this article, we attempt to define the effect of mean arterial pressure (MAP) during CPB on postoperative end-organ function. Although early studies reported that cerebral perfusion during hypothermic CPB is independent of MAP, recent laboratory and clinical reports have shown a positive slope in the MAP versus cerebral blood flow relationship. In clinical studies, patients who had higher MAPs during CPB had a lower incidence of cardiac and neurologic complications, as well as late neurocognitive abnormalities compared with patients with lower MAPs. Improving collateral flow in the setting of cerebral embolization has been postulated as the main mechanism for the improved neurologic outcomes in the high MAP groups. Higher perfusion pressure during CPB affects regional blood flow to the kidneys and visceral organs. However, the lower autoregulatory limits of perfusion to abdominal organs differ from the limits to the brain. Enhanced visceral perfusion during CPB is best achieved by increasing perfusion pressure via increases in perfusion flow rates rather than by using peripheral vasoconstriction alone. In conclusion, it is clear that maintenance of a high MAP during CPB may have a significant impact in protecting the brain and abdominal organs, particularly in the subset of patients at high risk for embolization and end-organ dysfunction.

Left atrial femoral bypass and cerebrospinal fluid drainage decreases neurologic complications in repair of descending and thoracoabdominal aortic aneurysms.

This study was undertaken to evaluate the role of cerebrospinal fluid (CSF) drainage and left atrial to femoral artery (LAFA) bypass in preventing postoperative neurologic complications for patients who had undergone descending and thoracoabdominal aortic aneurysm (TAAA) repair. LAFA bypass and CSF drainage were used as adjuncts in the treatment of 8 patients with descending and 13 patients with TAAAs (December 1999 to March 2000). LAFA bypass was established with the use of a centrifugal Biomedicus pump. Distal flows were maintained between 1.5 and 2.5 L/min during the procedures. Mean LAFA bypass time was 40 (range, 21 to 60 min). The CSF pressure was kept below 10-12 mmHg during the operations and for the first 72 hr postoperatively. All patients received heparin (1 mg/kg), which was reversed at the completion of the procedure. Passive hypothermia (rectal temperature: 32 degrees-34 degrees C) was used in all cases. All patent T8-L1 intercostal arteries were reattached to the graft. There were 13 men and 8 women. The median age was 56 years (range, 49 to 78). Chronic aortic dissection was the cause of the aneurysm in 9 patients (43%), trauma in 1 patient (5%), and medial degeneration in 11 patients (52%). There were four type I (19%), four type II (19%), and five type III (24%) TAAA. In eight patients (38%) the entire descending thoracic aorta was aneurysmal. Our results showed that the use of CSF drainage and LAFA bypass prevents paraplegia/paraparesis after repair of thoracoabdominal and descending thoracic aneurysms.

Predictors of mortality for patients undergoing cardiac valve replacements in New York State.

BACKGROUND: The objective of this study was to identify the mortality rates and significant independent risk factors for mortality for each of six valve replacement groups. METHODS: A total of 14,190 patients who underwent valve replacement in New York State from 1995 to 1997 were classified into six major groups and significant independent risk factors for inpatient mortality were identified for each of the groups using stepwise logistic regression. RESULTS: Mortality rates ranged from 3.33% for isolated aortic valve surgical procedures to 18.72% for multiple valve replacements with coronary artery bypass graft operations. The number of years in excess of age 55 was a significant multivariate predictor of mortality for all six groups of patients. Shock was a significant predictor for five of the six groups, and in each of those groups it was the risk factor with the highest odds ratio. CONCLUSIONS: Significant patient risk factors are relatively consistent across different types of valve replacement procedures. The probability of survival from valve surgical procedures is highly dependent on the patient's preoperative profile and the type of valve operation.

Particulate emboli capture by an intra-aortic filter device during cardiac surgery.

OBJECTIVE: Particulate embolization is associated with neurologic morbidity after cardiac surgery. Crossclamp manipulation has been identified as the single most significant cause of particulate emboli release during cardiac surgery. A new intra-aortic filtration method has been assessed with regard to its safety and its ability to capture particulate emboli before they enter the central circulation. METHODS: Patients undergoing cardiac surgery with cardiopulmonary bypass through standard median sternotomy were selected for emboli management by means of intra-aortic filtration. A novel intra-aortic filter device was inserted through a modified 24F arterial cannula immediately before releasing the crossclamp in 77 patients. Filters remained in the aorta until cardiopulmonary bypass was discontinued and the heart was fully ejecting. The procedure was assessed for facility, safety, and effect on routine cardiopulmonary bypass operation and function. RESULTS: The insertion and removal of the intra-aortic filter were safe, easy, and uneventful in most patients. Patient hemodynamics and bypass flow rates remained normal throughout the filter dwell period. No strokes or gross neurologic defects were noted. Electron microscopic analysis of 12 filters revealed an insignificant degree of platelet adhesion on filter surfaces. Histology samples (n = 44) were examined, and 66% (n = 29) showed evidence of atheromatous material, 36% (n = 16) with platelet-fibrin, 25% (n = 11) with true thrombus and/or blood clot, 7% (n = 3) with normal vessel wall, and 2% (n = 1) with aggregates of cholesterol or grumous portion of atheromatous plaque. CONCLUSION: The intra-aortic filter can be safely deployed and captures particulate emboli, the predominant origin of which is atheromatous. The beneficial effects of this device on neurologic outcomes have yet to be determined.

Local perivascular delivery of basic fibroblast growth factor in patients undergoing coronary bypass surgery: results of a phase I randomized, double-blind, placebo-controlled trial.

BACKGROUND: Angiogenesis is a promising treatment strategy for patients who are not candidates for standard revascularization, because it promotes the growth of new blood vessels in ischemic myocardium. METHODS AND RESULTS: We conducted a randomized, double-blind, placebo-controlled study of basic fibroblast growth factor (bFGF; 10 or 100 microg versus placebo) delivered via sustained-release heparin-alginate microcapsules implanted in ischemic and viable but ungraftable myocardial territories in patients undergoing CABG. Twenty-four patients were randomized to 10 microg of bFGF (n=8), 100 microg of bFGF (n=8), or placebo (n=8), in addition to undergoing CABG. There were 2 operative deaths and 3 Q-wave myocardial infarctions. There were no treatment-related adverse events, and there was no rise in serum bFGF levels. Clinical follow-up was available for all patients (16.0+/-6.8 months). Three control patients had recurrent angina, 2 of whom required repeat revascularization. One patient in the 10-microg bFGF group had angina, whereas all patients in the 100-microg bFGF group remained angina-free. Stress nuclear perfusion imaging at baseline and 3 months after CABG showed a trend toward worsening of the defect size in the placebo group (20.7+/-3.7% to 23.8+/-5.7%, P=0.06), no significant change in the 10-microg bFGF group, and significant improvement in the 100-microg bFGF group (19.2+/-5.0% to 9.1+/-5.9%, P=0.01). Magnetic resonance assessment of the target ischemic zone in a subset of patients showed a trend toward a reduction in the target ischemic area in the 100-microg bFGF group (10.7+/-3.9% to 3. 7+/-6.3%, P=0.06). CONCLUSIONS: This study of bFGF in patients undergoing CABG demonstrates the safety and feasibility of this mode of therapy in patients with viable myocardium that cannot be adequately revascularized.

Venovenous modified ultrafiltration after cardiopulmonary bypass in children: a prospective randomized study.

BACKGROUND: Cardiopulmonary bypass is associated with the production of both proinflammatory and anti-inflammatory cytokines, the balance of which leads to varying degrees of postoperative systemic inflammation. Arteriovenous modified ultrafiltration effectively reduces total body water and improves postoperative hemodynamic and homeostatic functions. Venovenous modified ultrafiltration is a modification of this technique, which has the potentially added advantage of eliminating the obligatory left-to-right shunt associated with arteriovenous modified ultrafiltration. We tested the hypothesis that venovenous modified ultrafiltration is a safe and effective method of achieving ultrafiltration in children after cardiopulmonary bypass. METHODS: Thirty-eight pediatric patients were randomly assigned to undergo conventional, venovenous (n = 13), or no ultrafiltration venovenous (n = 13), and controls (n = 12). Perioperative, cardiopulmonary, and cytokine (tumor necrosis factor-alpha, interleukin-1beta, interleukin-6, interleukin-8, and interleukin-10) data were collected for statistical analysis. RESULTS: Compared with patients in the conventional ultrafiltration and control groups, patients undergoing venovenous modified ultrafiltration had the greatest volume of ultrafiltrate removed (46. 9 +/- 8.4 mL/kg vs 20.1 +/- 5.0 mL/kg and 0 mL/kg for conventional ultrafiltration and control groups, respectively; P =.0001), least increase in total body water (1.91% +/- 1.49% vs 3.90% +/- 1.86% and 8.24% +/- 3.41%; P =.05), greatest rise in hematocrit (39.7% +/- 1. 7% vs 33.8% +/- 2.1% and 29.6% +/- 2.3%; P =.006), and shortest length of hospital stay (4.41 +/- 0.28 days vs 6.69 +/- 1.47 days and 8.38 +/- 1.11 days; P =.03, P =.03). CONCLUSIONS: Venovenous modified ultrafiltration is a safe and effective method of reducing the increase in total body water and duration of postoperative convalescence after cardiopulmonary bypass.

Preoperative identification and operative management of intraatrial extension of lung tumors.

Preoperative identification of intraatrial tumor is uncommon. A 23-year-old woman presented with local recurrence and pulmonary metastases after previous resection of a clavicular sarcoma. Evaluation by computed tomography revealed bilateral pulmonary masses. Due to the size and proximal location, magnetic resonance imaging and transesophageal echocardiography were performed, revealing a large intraatrial mass. She then underwent staged surgical excision without intraoperative complications. We summarize this case and review risk factors for intracardiac extension and prevention of tumor emboli.

Comprehensive multimodality blood conservation: 100 consecutive CABG operations without transfusion.

BACKGROUND: Despite the recent introduction of a number of technical and pharmacologic blood conservation measures, bleeding and allogeneic transfusion remain persistent problems in open heart surgical procedures. We hypothesized that a comprehensive multimodality blood conservation program applied algorithmically on the basis of bleeding and transfusion risk would provide a maximum, cost-effective, and safe reduction in postoperative bleeding and allogeneic blood transfusion. METHODS: One hundred consecutive patients undergoing coronary artery bypass grafting were prospectively enrolled in a risk factor-based multimodality blood conservation program (MMD group). To evaluate the relative efficacy and safety of this comprehensive approach, comparison was made with a similar group of 90 patients undergoing coronary artery bypass grafting to whom the multimodality blood conservation program was not applied but in whom an identical set of transfusion guidelines was enforced (control group). To evaluate the cost effectiveness of the multimodality program, comparison was also made between patients in the MMD group and a consecutive series of contemporaneous, diagnostic-related group-matched patients. RESULTS: One hundred consecutive patients in the MMD group underwent coronary artery bypass grafting without allogeneic transfusion. This compared favorably with the control population in whom a mean of 2.2 +/- 6.7 units of allogeneic blood was transfused per patient (34 patients [38%] received transfusion). In addition, the volume of postoperative blood loss at 12 hours in the control group was almost double that of the MMD group (660 +/- 270 mL versus 370 +/- 180 mL [p < 0.001]). Total costs for the MMD group in each of the three major diagnostic-related groups were equivalent to or significantly less than those in the consecutive series of diagnostic-related group-matched patients. CONCLUSIONS: Comprehensive risk factor-based application of multiple blood conservation measures in an optimized, integrated, and algorithmic manner can significantly decrease bleeding and need of allogeneic transfusion in coronary artery bypass grafting in a safe and cost-effective manner.

Impact of minimum hematocrit during cardiopulmonary bypass on mortality in patients undergoing coronary artery surgery.

BACKGROUND: The hematocrit on cardiopulmonary bypass (CPB) frequently falls to a low level during many cardiac surgical procedures. This study was designed to explore the impact on mortality of minimum hematocrit level achieved during the CPB after coronary artery surgery. METHODS AND RESULTS: Two thousand seven hundred thirty-eight sequential isolated coronary artery surgery patients during a 42-month period at a tertiary academic center were included in this study. Thirty-one standardized preoperative risk factors used in a multiple logistic regression revealed eight statistically significant independent predictors for postoperative mortality. Minimum hematocrit level during CPB was then added to the regression model and was found to be an independent risk factor for mortality. The entire patient population was divided into dichotomous groups using different minimum hematocrit levels on CPB for the determination of cutoff points by multiple logistic regression. After adjusting for other risk factors, the minimum hematocrit level of 14% was found to be a statistically significant cutoff point. Patients with minimum hematocrit levels < or =14% were found to have an increased probability of risk-adjusted mortality (odds ratio, 2.70; P=.002). A subgroup analysis revealed that high-risk patients with minimum hematocrit levels < or =17% were found to have a significantly increased probability of postoperative mortality (odds ratio, 2.20; P=.017). CONCLUSIONS: Minimum hematocrit level during CPB is an independent risk factor for mortality after coronary artery surgery. There is a significantly increased risk of mortality for hematocrit levels < or =14%. For high-risk patients, there is a significantly increased risk of mortality for hematocrit levels < or =17%.

Aortic atheroma is related to outcome but not numbers of emboli during coronary bypass.

BACKGROUND: The relation between aortic atheroma severity and stroke after coronary artery bypass grafting is established. The relation between atheroma severity and other outcome measures or numbers of emboli has not been determined. METHODS: Using transesophageal echocardiography, we determined the severity of atheroma in the ascending, arch, and descending aortic segments in 84 patients undergoing operations. Seventy patients were monitored using transcranial Doppler ultrasonography. RESULTS: The incidence of stroke was 33.3% among 9 patients with mobile plaque of the arch and 2.7% among 74 patients with nonmobile plaque (p = 0.011). Cardiac complications were not significantly related to atheroma severity in any aortic segment. Length of stay was significantly related to atheroma severity in the aortic arch (p = 0.025) and descending segment (p = 0.024). The presence of severe atheroma in both the arch and descending segments was associated with significantly longer hospital stays as compared with patients with severe atheroma in neither segment (p = 0.05). Numbers of emboli were greater in patients with severe atheroma at clamp placement, although the differences did not achieve statistical significance. CONCLUSIONS: Aortic atheroma severity is related to stroke and to the duration of hospitalization after coronary artery bypass grafting. The lack of correlation between numbers of emboli and atheroma severity suggests that m any emboli may be nonatheromatous in nature.