Aurel C. Cernaianu

A pilot study of the effects of a perflubron emulsion, AF 0104, on mixed venous oxygen tension in anesthetized surgical patients.

A pilot study of a perfluorochemical (PFC) emulsion was undertaken to determine whether administration of a perflubron emulsion could result in measurable changes in mixed venous oxygen tension.Seven adult surgical patients received a 0.9-g PFC/kg intravenous dose of perflubron emulsion after acute normovolemic hemodilution (ANH). Hemodynamic and oxygen transport data were collected before and after ANH, immediately after PFC infusion, and at approximate 15-min intervals throughout the surgical period. There were no clinically significant hemodynamic changes associated with the administration of the PFC emulsion. There was a significant increase in mixed venous oxygen tension (PVO2) after the PFC infusion, while cardiac output and oxygen consumption were unchanged. As surgery progressed, the hemoglobin concentration decreased with ongoing blood loss while PVO2 values remained at or above predosing levels. Peak perflubron blood levels were 0.8 g/dL immediately postinfusion, and approximately 0.3 g/dL at 1 h. This pilot study demonstrates that administration of perflubron emulsion results in measurable changes in mixed venous oxygen tension during intraoperative ANH. (Anesth Analg 1996;82:103-7)

Heparinless extracorporeal bypass for treatment of hypothermia.

In an attempt to assess the changes occurring to the coagulation profile during internal active core rewarming with partial cardiopulmonary bypass (CPB) without heparin anticoagulation, five pigs were anesthetized, and a model for severe to moderate hypothermia was created. Femoral-femoral bypass with Bio-Pump, heat exchanger, and a membrane oxygenator were used during the rewarming for 64.8 +/- 8.5 minutes. There were no statistically significant changes in platelet count, platelet index, activated clotting time (ACT), partial thromboplastin time (PTT), prothrombin time (PT), fibrinogen, fibrinogen index and fibrin split products (p greater than 0.05). There were no thromboembolic sequelae seen at autopsy. The components of the CPB circuit showed no signs of formation of aggregates or thrombi. The results of this study are attributed to the nonthrombogenic, atraumatic design of the Bio-Pump and the enhanced physiological fibrinolysis seen in the first hour of CPB. We concluded that heparinless CPB may serve as a safe alternative for active core rewarming for severe to moderate hypothermia.

Effect of sodium nitroprusside on paraplegia during cross-clamping of the thoracic aorta

Sodium nitroprusside (SNP) is usually used to control excessive proximal pressure after aortic cross-clamping. To assess the effect of SNP on circulatory dynamics, somatosensory evoked potentials, and neurologic outcome, 10 adult mongrel dogs that underwent 45 minutes of cross-clamping of the thoracic aorta were randomly assigned to receive either 50 mg/kg of SNP or no treatment for excessive proximal hypertension. There was a statistically significant difference noted between the SNP-treated animals and the control animals in terms of the proximal mean arterial pressures (112 +/- 13 versus 142.2 +/- 15 mm Hg, respectively; p < 0.05) and the mean distal arterial pressures (15 +/- 3 mm Hg versus 23 +/- 1 mm Hg; p = 0.04). However, the electrical activity of the spinal cord, as indicated by the somatosensory evoked potentials, returned significantly faster in the nontreated group than in the SNP-treated group (15 +/- 9 versus 44 +/- 13 minutes; p < 0.05). Control animals exhibited a significantly better neurologic outcome and no paraplegia 24 hours postoperatively. We conclude that the use of SNP to treat excessive proximal hypertension may be detrimental to the spinal cord during cross-clamping of the thoracic aorta, resulting in a decline in the ischemic tolerance.

Latissimus dorsi and serratus anterior dynamic descending aortomyoplasty for ischemic cardiac failure

Dynamic descending aortomyoplasty for cardiac assistance is a form of extraaortic, skeletal muscle-driven counterpulsation. Controversy exists regarding its clinical applicability and the most suitable muscle autograft for the procedure. Specifically, the ligation of intercostal vessels required for descending aortomyoplasty may not be tolerated clinically. This study compared the hemodynamic profiles and long-term function of latissimus dorsi (LD) aortomyoplasty to a split serratus anterior (SA) descending aortomyoplasty in which all intercostal vessels were preserved. Descending aortomyoplasty was performed in 11 goats. In 5, the SA was harvested and its distal end divided, facilitating a wrap of the aorta without ligation of intercostal arteries. In 6, the LD was used as a circumferential aortic wrap. At 90 days, an occluder placed on the left anterior descending artery created an ischemic event. Hemodynamic studies with and without assistance were performed in the ischemic and nonischemic states. Latissimus dorsi aortomyoplasty improved cardiac output 24% and 5.6%, stroke volume 29% and 66%, left ventricular stroke work index 30% and 166%, and coronary flow 4% and 3% in the normal and ischemic heart, respectively. Serratus anterior aortomyoplasty improved cardiac output 36% and 10%, stroke volume 42.8% and 13.5%, left ventricular stroke work index 64% and 21%, and coronary flow 8% and 4.3%, in the normal and ischemic heart, respectively. Two of the SA autografts were fibrotic and nonfunctional at 3 months. Aortomyoplasty with either SA or LD muscle improves cardiac function in the normal and ischemic heart. However, divided SA is associated with a higher rate of fibrosis and may be less suitable for the procedure.

Perfluorocarbons as blood substitutes: the early years. Experience with Fluosol DA-20% in the 1980s.

Clinical testing of perfluorocarbons (PFC) as blood substitutes began in the early 1980s in the form of Fluosol DA-20% (FDA), a mixture of perfluorodecalin and perfluorotripropylamine emulsified with Pluronic F68. We have treated 55 patients (Treatment (T) = 40; Control (C) = 15) with intravenous infusions of 30 cc/kg of FDA as part of either a randomized, clinical trial or a humanitarian protocol. All patients were Jehovahs Witnesses who refused blood transfusion and were severely anemic (mean hemoglobin = 4.6 g/d). FDA successfully increased dissolved or plasma oxygen content (P1O2 in ml/dl), but not overall oxygen content (T group: P1O2 baseline = 1.01 +/- .27, P1O2 12hrs = 1.58 +/- .47 [p = < .0001, t-test]; P1O2 12 hrs: T = 1.58 +/- .47, C = 1.00 +/- .31, p = < .0002, t-test). This effect persisted for only 12 hours post infusion, and had no apparent effect on survival. FDA is an ineffective blood substitute because of low concentration and short half-life. Improved emulsion design may resolve these problems, thereby producing a more effective agent. Our discussion will include a review of our data plus a summary of other reports of FDA efficacy as a blood substitute.

Descending thoracic aortomyoplasty: a technique for clinical application.

BACKGROUND Descending thoracic aortomyoplasty is a form of skeletal muscle-powered cardiac assistance. Its use in clinical settings has been limited by the ligation of intercostal arteries necessary to complete a circumferential wrap of the aorta with the latissimus dorsi. METHODS This study assessed the feasibility and the efficacy of aortomyoplasty constructed with a modified latissimus dorsi. A pericardial patch was attached to the latissimus dorsi and divided around the preserved intercostal arteries. Nine alpine goats (37 +/- 2 kg) underwent descending aortomyoplasty using this technique. All intercostal arteries were preserved. After a 6-week recovery period, the animals underwent a 6-week, incremental electrical conditioning program. After 90 postoperative days, animals were examined under anesthesia with the myostimulator on and off. RESULTS Aortomyoplasty activation resulted in augmentation of mean diastolic aortic pressure by 16.0 +/- 0.9 mm Hg (23%). Significant improvements in cardiac index (40%), stroke volume index (37%), left ventricular stroke work index (49%), and mean arterial pressure (19%) were noted. An intravascular sonographic probe placed in the descending aorta revealed circumferential compression of the aorta during counterpulsation. Mean cross-sectional aortic area was reduced by 51.8%, from 210.1 +/- 7.1 to 108.9 +/- 6.7 mm2 during aortomyoplasty activation (p < 0.05). Histologic analysis confirmed the long-term patency of intercostal arteries. CONCLUSIONS Descending aortomyoplasty, modified with an interposing patch of pericardium, effectively transfers skeletal muscle force across the aortic wall and assists cardiac function. This technique allows preservation of all aortic branches, and with this novel approach, the clinical utility of aortomyoplasty can now be explored.

A Surgical Approach to Chronic Aortomyoplasty in the Goat Model

The left latissimus dorsi skeletal muscle of seven male goats was prepared and applied circumferentially to the descending aorta just below the subclavian artery. Stimulation of the neural pedicle of the latissimus dorsi was performed in an attempt to convert it to a fatigue-resistant cardiac-like muscle. Timing of the stimulus was in diastole. Biochemical assays established the conversion, and echocardiography demonstrated aortic compressions in the area of the muscle wrap. Although limited in numbers, the converted latissimus dorsi muscle in the extra-aortic position appears to provide diastolic augmentation.

Long-Term Results of Simultaneous Carotid Endarterectomy and Coronary Artery Revascularization in Patients with Unstable Angina and Cerebrovascular Insufficiency

This study assessed the outcome of 11 consecutive high-risk patients (8 men, 3 women) with symptomatic, high-grade (greater than 70%) bilateral carotid stenosis and left main or triple-vessel disease with unstable angina undergoing emergency simultaneous carotid endarterectomy (CEA) and coronary artery bypass grafting (CABG) revascularization. Seven patients presented with crescendo unstable angina and 4 had type III postinfarc tion unstable angina. All were symptomatic for cerebrovascular insufficiency. Six patients had left main and 5 patients had triple-vessel disease aside from bilateral carotid lesions. There were 8 men and 3 women, (mean age 69.1 ± 3.9 years). The mean preoperative end-diastolic pressure and ejection fraction were 17.2 ±2.4 mm Hg and 35.3 ±6.9%, respectively. Sequential reconstruction of the carotid artery was followed by CABG with an average number of 3.1 ± 0.3 grafts per patient. One patient had additional aortic valve replace ment and 1 had an automatic implantable cardioverter defibrillator implanted. There was no operative mortality. The overall neurologic complication rate was 27.3% (3 of 11). One patient developed perioperative myocardial infarction and 1 other had respira tory failure. Mean postoperative hospital stay was 24.4 ±4.8 days. Within one year postoperation, 1 patient died. Two patients had contralateral CEA owing to recurrent transient ischemic attack. The five-year probability of survival was 89%. Our data show that simultaneous CEA/CABG in patients with high-risk coronary and cerebrovascular insufficiency may result in low mortality; however, a relatively increased incidence of short- and long-term morbidity is expected.

Silicone pouch for protection of automatic implantable cardioverter-defibrillator leads

Automatic implantable cardioverter-defibrillator has become routine treatment for recurrent, drug-resistant ventricular tachycardia. Although there is documentation regarding clinical experience and device performance, there is little information on how to avoid complications related to the retrieval of sensing and defibrillation leads from the subcutaneous space. We are reporting our experience with a silicone pouch for protection of automatic implantable cardioverter-defibrillator leads that allows immediate and simple retrieval of the leads in case an automatic implantable cardioverter-defibrillator generator is needed.

Improvement of spinal cord electrical activity with lazaroid (U74006F) during operations on the thoracic aorta: evaluation of a novel lipid peroxidation inhibitor

Reperfusion injury may contribute to spinal cord damage after cross-clamping of the thoracic aorta (AXC). Tirilazad (U74006F), a potent free radical scavenger and lipid peroxidation inhibitor, has proven to be beneficial in ischemia/reperfusion models. The authors investigated the efficacy of U74006F in preventing paraplegia following forty-five minutes of normothermic AXC distal to the origin of the left subclavian artery. Thirty-two mongrel dogs were assigned to receiving either vehicle as pretreatment (control, n = 7) or 1.5 mg/kg U74006F (group II, n=7) or 3 mg/kg U74006F (group III, n = 10) infused into the descending aorta distal to the clamp for twenty minutes during reperfusion, or 3 mg/kg U74006F IV as pretreatment twenty-five minutes before the onset of ischemia (group IV, n = 8). Mean proximal (BPpr) and distal (BPdx) aortic pressures and somatosensory evoked potentials (SEP) were measured at baseline and at minutes 2, 5, 7, 10, 15, 30, and 45 after AXC. SEP and neurologic outcome (Tarlov criteria) were assessed twenty-four hours postprocedure. There was no difference between BPpx or BP dx and their counterparts in the U74006F-treated animals and the control. SEP returned faster in all treatment groups when compared with controls. However, the neurologic outcome did not differ among groups. The authors conclude that although U74006F did not improve the neurologic outcome, it had a positive effect on the recovery of electrical activity of the spinal cord following transient ischemia. This suggests that the injury to the spinal cord induced by AXC is caused, in part, during reperfusion.