Intercellular and vascular cell adhesion molecule levels in endoscopic and open saphenous vein harvesting for coronary artery bypass surgery

BACKGROUND

Numbers of intercellular and vascular cell adhesion molecules (ICAM and VCAM) and major ligands on endothelial cells for adherence of activated polymorphnuclear leukocytes, macrophages, and lymphoid cells increase in many inflammatory disorders and after trauma to different tissues.

METHODS

Samples of human saphenous veins were harvested from 90 randomly selected patients who underwent coronary artery bypass graft (CABG) surgery, utilizing two different techniques (open and endoscopic). Endothelial cells were collected from the vein samples and cultured for 72 hours. Pre- and postoperative sera, in addition to the supernatants from the cultures, were analyzed for ICAM-1 and VCAM-1 using enzyme-linked immunosorbent assay.

RESULTS

Mean preoperative levels of ICAM-1 and VCAM-1 (0.95 +/- 0.58 ng/mL and 1.81 +/- 1.03 ng/mL, respectively) did not differ significantly from that of postoperative sera (0.98 +/- 0.451 ng/mL and 1.74 +/- 1.05 ng/mL, respectively) (p = 0.77 and p = 0.73, respectively). Mean ICAM-1 and VCAM-1 levels in endothelial cell culture supernatants did not differ significantly between the endoscopic (0.16 +/- 0.05 ng/mL and 0.23 +/- 0.10 ng/mL, respectively) and the open method (0.18 +/- 0.08 ng/mL and 0.30 +/- 0.27 ng/mL, respectively) (p = 0.19 and 0.13, respectively).

CONCLUSION

Our findings indicate that endoscopic and open saphenectomies are technically comparable in their effects on ICAM-1 and VCAM-1 synthesis during saphenous vein harvesting for CABG. We recommend the endoscopic method for its low morbidity and earlier hospital discharge.

A cytokine analysis of the effect of cell saver on blood in coronary bypass surgery

BACKGROUND

Increasing concern about the transmission of viral disease has generated greater interest in the use of salvaged blood as a means of alleviating the demand for homologous blood and expediting resuscitation during massive hemorrhage. Autologous blood processed by autotransfusion devices has become increasingly common in major surgery and is now largely viewed as safe and efficacious. However, there may be serious complications and sequelae associated with the use of processed blood, such as adult respiratory distress syndrome (ARDS) and renal failure. Complement cascade activation resulting from blood coming into contact with autotransfusion equipment leads to enrollment of leukocytes and release of large concentrations of cytokines, which may contribute to the development of organ failure. Our study evaluated cytokine release during cell saver (CS) blood salvage in the course of coronary artery bypass grafting (CABG) surgery.

MATERIALS AND METHODS

Forty-five patients randomly selected for CABG were evaluated. All had received at least one unit of autotransfused blood by means of the Haemonetics Cell Saver System 5 (Haemonetics Corp., Braintree, MA). Each patient had four blood samples taken (pre-operative, CS container, autotransfusion from the blood bag, and one hour post-transfusion). These samples were then centrifuged and the sera were collected. An enzyme linked immunosorbent assay (ELISA) test, using the Biosource Cytoscreen solid phase "sandwich" ELISA kit (Biosource International, Camarillo, CA) was conducted to determine levels of the cytokines Interleukin (IL) 1, 2, 4, 6, 8, and 10, tumor necrosis factor (TNF), intracellular adhesion molecule (ICAM), and vascular cell adhesion molecule (VCAM).

RESULTS

Significantly increased concentrations of the pro-inflammatory cytokines IL-1, 2, 4, 6, and 8, TNF, ICAM, and VCAM were noted throughout all time periods studied. The same effect was observed for the anti-inflammatory cytokine IL-10.

CONCLUSION

Statistically significant increases in both the circulating levels of the pro-inflammatory and anti-inflammatory cytokines studied were recorded. It is our contention that the presence of IL-10, a down-regulator of inflammation, is responsible for attenuating the possible deleterious effects of the pro-inflammatory cytokines observed. However, morbidity and mortality, as well as the future patency of the bypass grafts, have not been correlated with the use of the autologous method of transfusion.

A comparative study of endothelial cell injury during open and endoscopic saphenectomy: an electron microscopic evaluation

BACKGROUND

The role of damaged endothelium in early graft occlusion has been extensively demonstrated. Seventy percent of early graft occlusions in coronary artery bypass were caused by thrombi overlying areas of endothelial loss. With the increased use of endoscopic vein harvesting, it becomes important to study the extent of endothelial damage by light and electron microscopy. In this study, we compared the degree of endothelial damage inflicted by the open and endoscopic techniques of vein harvesting using light, scanning, and transmission electron microscope.

MATERIAL AND METHODS

Ninety samples of saphenous veins from 45 patients prepared for coronary artery bypass grafting (CABG) utilizing both endoscopic and standard open incision techniques were examined using light, scanning, and transmission electron microscopy. These vein samples were prepared in Plasma-lyte solution (Baxter) in combination with or without papaverine, at two distending pressures of 100 or 300 mmHg and at temperatures of either 4 degrees C or 28 degrees C in eight subgroups and one control group. The pathological alterations in the saphenous veins were graded either based on a scoring system (0 = none, 1 = < 10%, 2 = 10-25%, 3 = 25-50%, 4 = > 50%) to assess the degree of damage inflicted by these two different types of saphenectomies or by electron microscopic observed abnormalities, including endothelial cell (EC) separation, EC detachment, basement membrane (BM) exposure, collagen exposure, and EC edema.

RESULTS

Using cross-tabulation and Chi-square statistical analysis, we found that the differences in the degree of endothelial damage using either of the techniques is not statistically significant (P > 0.05).

CONCLUSION

Our findings indicate that endoscopic and open saphenectomies are technically comparable as far as structural damage is concerned, rendering the endoscopic technique of vein handling the preferred method for CABG.

Interleukin-1, interleukin-2 and interleukin-10 expression in different techniques of saphenous vein harvesting

BACKGROUND

Levels of the cytokines Interleukin-1 (IL-1), IL-2, and IL-10 are sensitive to the traumatic effect of saphenous vein harvesting. Their levels are compared between the endoscopic and traditional open techniques of harvesting.

METHODS

Samples of human saphenous veins were harvested from 90 randomly selected patients undergoing coronary artery bypass surgery (CABG), using the open or endoscopic techniques. Endothelial cells collected from the vein samples retrieved through both techniques were cultured for 72 hours. Pre and postoperative sera, in addition to the supernatants from the cultures, were analyzed for IL-1, IL-2, and IL-10 using ELISA.

RESULTS

Mean preoperative concentrations of IL-1, Il-2, and IL-10 were 0.11+/- 0.04, 0.09 +/- 0.04, and 0.09 +/- 0.04 pg/ml, respectively. Corresponding values for postoperative sera were 0.13 +/- 0.08, 0.12 +/- 0.10, 0.14 +/- 0.17 pg/ml, respectively. The differences between pre and postoperative means for each cytokine were not statistically significant (p = 0.13, 0.18, 0.05, respectively). Mean IL-1, IL-2, and IL-10 concentrations for endothelial cell culture supernatants did not differ significantly between the endoscopic (0.17 +/- 0.11, 0.11 +/- 0.05, and 0.32 +/- 0.40 pg/ml, respectively) and the open method (0.19 +/- 0.16, 0.11 +/- 0.05, and 0.46 +/- 0.80 pg/ml, respectively) (p = 0.48, 0.81, 0.30, respectively).

CONCLUSION

Since endoscopic and open saphenectomies are technically comparable with respect to their effects on IL-1, Il-2, and IL-10 levels, we recommend the endoscopic method for its lower morbidity and the potential for earlier hospital discharge.

Significance of interferon-gamma in coronary artery bypass surgery

BACKGROUND

Gamma interferon (IFN-gamma) is produced by activated natural killer and T cells under pathologic circumstances. The objective of our study was to compare the level of IFN-gamma in open and endoscopic methods of vein harvesting for coronary artery bypass surgery (CABG).

METHOD

Ninety samples of human saphenous veins harvested from patients prepared for CABG. Pre- and post-procedure sera of the patients, in addition to supernatants of 3-day endothelial cell culture, were analyzed for IFN-gamma.

RESULTS

The mean preoperative IFN-gamma level (0.09+/-0.03 pg/mL) and that for postoperative sera (0.08+/-0.02 pg/mL) were not significantly different (P = 0.2). The mean IFN-gamma level in endothelial cell culture from the endoscopic (0.18+/-0.21 pg/mL) and the open method (0.19+/-0.39 pg/mL) were not significant (P = 0.89).

CONCLUSION

We recommend the endoscopic method of vein harvesting because of its lower morbidity and earlier hospital discharge.

Saphenous vein endothelial cell viability: a comparative study of endoscopic and open saphenectomy for coronary artery bypass grafting

BACKGROUND

The use of endoscopic saphenous vein harvesting (ESVH) for coronary artery bypass grafting (CABG) is growing. This study was done to investigate the extent of endothelial injury in ESVH compared with that of the standard open method (OSVH), and under various physical and chemical preservation factors.

METHODS

We endoscopically removed the saphenous vein from 45 consecutive patients undergoing saphenectomy for CABG together with a segment retrieved by the no-touch OSVH method. Vein samples from each group were divided into 8 subgroups of 5 samples each, and incubated in Plasma-Lyte solution with or without papaverine, at distending pressures of 100 or 300 mm Hg, and at either 4 degrees C or 28 degrees C, respectively. A ninth subgroup was preserved at room temperature without pressure or papaverine. The viability of cultured saphenous vein endothelial cells was assessed by counting the number of total cells and deriving the proportion of viable cells, following incubation for 72 hours.

RESULTS

The median proportion of viable cells (PVC) showed a slight decline over days 0 to 4 for both harvesting methods. No significant difference existed in the median PVC between the two techniques (day 0: 75%, 72%, P = 0.8; day 1: 66.7%, 66.7%, P = 0.9; day 2: 66.7%, 66.7%, P = 0.3; day 3: 65.3%, 66.7%, P = 0.16, respectively). The mean PVC compared across temperatures of 4 degrees C, 28 degrees C, and room temperature for the ESVH was highly significant, with the highest value being for room temperature (69.5%, 56.4%, 70.3%, respectively, P = 0.0003). Results for the OSVH were not significant. The effect of distension pressure did not vary significantly for 0, 100, and 300 mm Hg for both techniques (70.3%, 63.2% and 63.4%, respectively, P = 0.46 for the ESVH; 66.5%, 68.4%, 67.4%, respectively, P = 0.94 for the OSVH). The addition of papaverine improved PCV slightly for the OSVH only (61.7%, 64.3%, respectively, P = 0.02), whereas that for the ESVH was not significant (67.3%, 72.5%, P = 0.12).

CONCLUSION

The effect of ESVH on endothelial cell viability is comparable to that of the OSVH. Among the factors influencing endothelial viability during vein preparation, temperature had a major effect with lower temperatures in the range of 4 degrees C to room temperature being the most favorable one. Mechanical distension and papaverine had unimportant or inconsistent roles. We recommend the ESVH as the procedure of choice for saphenous vein harvesting due to the lower postoperative morbidity, and the lower incubation temperature needed for its better influence on potential graft patency.

Composite cardiac binding in experimental heart failure

BACKGROUND

Composite cardiac binding consists of wrapping the heart with a synthetic membrane and a pericardial interposition. The goal of the present study was to apply composite cardiac binding to a canine model of heart failure.

METHODS

Twenty dogs were randomized to 2 groups: untreated heart failure (group 1, n = 13) and heart failure pretreated by composite cardiac binding (group 2, n = 7). They received a total dose of 1 mg x kg(-1) of intracoronary doxorubicin over 4 weeks. Hemodynamic data were obtained at weeks 0, 7, and 12. All animals were followed up with weekly echocardiography for 12 weeks.

RESULTS

Survival in group 1 was 54% and in group 2 was 100% at week 12 (p = 0.0438). Left ventricular end-diastolic pressure increased by 153% in group 1 and by 59% in group 2 (p = 0.0395) at week 12. Ejection fraction decreased by 27% in group 1 and by 19% in group 2 (p = 0.4401) at week 12.

CONCLUSIONS

Composite cardiac binding significantly prolongs survival and attenuates left ventricular dilatation and the increase in left ventricular end-diastolic pressure associated to chronic heart failure. Further evaluation in established heart failure is needed. Composite cardiac binding may be used for the prevention of recurrent dilatation following reduction ventriculoplasty.

Studies in thoracic aortic graft infections: the development of a porcine model and a comparison of collagen-impregnated dacron grafts and cryopreserved allografts

OBJECTIVE

A porcine model of thoracic aortic graft infection was created, and various anatomic sites and the timing of inoculation of the graft to induce infection were investigated. Ultimately, the ability of cryopreserved allograft to resist infection was compared with that of collagen-impregnated Dacron graft.

METHODS

Yorkshire pigs (n = 16) underwent placement of an expanded polytetrafluoroethylene patch graft in the ascending aorta and the left atrial appendage (phase I). Eight animals were immediately given a 50-mL bolus (1 x 10(8) cfu/mL) of Staphylococcus aureus whereas the other 8 received the infusion 24 hours later. Animals were put to death 8 weeks later and the grafts were sterilely explanted and analyzed via microbiologic culture and standard histologic procedures for evidence of infection. The results displayed that the aortic graft and a delay of induced bacteremia of 24 hours were more reliable methods of producing infection. During phase II, 13 pigs were randomized to receive either a collagen-impregnated Dacron graft (n = 6) or a cryopreserved allograft (n = 7) in the ascending aortic position only and infusion of S aureus 24 hours after the operation. The experiment then proceeded to completion.

RESULTS

Phase I results displayed that use of an aortic graft and induced bacteremia 24 hours after the operation was a more reliable and reproducible method of producing infection. In phase II, graft infection was present in 38.5% (5/13) of animals, with only 16.7% (1/6) in the collagen-impregnated Dacron graft group and 57.2% (4/7) in the cryopreserved allograft group becoming infected. There was no significant difference between the collagen-impregnated Dacron graft and cryopreserved allograft groups in the incidences of thoracic aortic graft infections (P =.27, Fisher exact test).

CONCLUSIONS

This novel porcine model of thoracic aortic graft infection is a reproducible method for the investigation of thoracic aortic graft infections. The phase I study investigated the timing of the induced bacteremia and the most susceptible position of a graft. Phase II demonstrated that collagen-impregnated Dacron grafts are equivalent, if not superior, to cryopreserved allografts in resisting central vascular graft infections in the ascending aorta.

Public reporting of surgical mortality: a survey of New York State cardiothoracic surgeons

BACKGROUND

Public disclosure of individual surgeons mortality following coronary artery bypass (CAB) is part of the New York State Department of Health Cardiac Surgery Reporting System (CSRS). The effects on the practice of cardiac surgery, as perceived by surgeons, remain unknown.

METHODS

All 150 New York State cardiac surgeons were sent an anonymous mail survey in 1997. Data was analyzed to determine the dominant opinion regarding the CSRS.

RESULTS

One hundred and four surgeons (69.3%) responded. The majority (70%) did not experience a change in practice. Data reporting was performed by the surgeon or an employee (58%). Many picked the incorrect definition of chronic obstructive pulmonary disease (COPD) (45%) or statistical method (60%). The aspect of CSRS most in need of improvement was gaming with risk factors (40%). Most surgeons (62%) refused to operate on at least one high-risk CAB patient over the prior year, primarily because of public reporting. Refusal was more common in surgeons in practice less than 10 years, those with less than 100 cases per year, and those with a mixed cardiothoracic practice (p < 0.05, Pearson's chi2 test). A significantly higher percentage of high-risk CAB patients were treated non-operatively, when compared with ascending aortic dissection patients (not disclosed) (p < 0.001, Wilcoxon signed ranks test).

CONCLUSIONS

The public disclosure of surgical results may be based on imperfect data and appears to have resulted in denial of surgical treatment to high-risk patients.

Combined coronary artery bypass grafting and abdominal aortic aneurysm repair

BACKGROUND

We report here the results of combined coronary artery bypass grafting (CABG) and abdominal aortic aneurysm (AAA) repair and the factors associated with higher mortality following this procedure.

METHODS

The authors performed a retrospective chart review of 26 patients who underwent combined CABG and AAA repair between March 1990 and October 1996.

RESULTS

No postoperative myocardial infarction or major cardiac complications were noted. A morbidity rate of 38% (n = 10) and mortality rate of 11% (n = 3) were noted. Comparative analysis of nonsurvivors (n = 3) versus survivors (n = 23) revealed the following: ejection fraction (EF) was significantly lower (33% +/- 3% versus 44% +/- 14%, P < 0.05), duration of cardiopulmonary bypass (CPB) was significantly longer (239 +/- 122 minutes versus 141 +/- 54 minutes, P < 0.05), and incidence of postoperative respiratory failure (67% versus 17%, P = 0.001) were significantly higher in nonsurvivors. No differences in mean age, gender distribution, incidence of hypertension or diabetes were noted between the groups.

CONCLUSIONS

Combined CABG and AAA repair protected patients from postoperative aneurysm rupture and myocardial infarction. Poor EF, prolonged CPB, and postoperative respiratory failure were associated with higher mortality.

Nonsurgical pneumoperitoneum: a case report and a review

The finding of extraluminal gas on plain radiographs is usually associated with a perforated viscus. But, as this case shows, the finding of pneumoperitoneum is not pathogenic of a perforated viscus or even of a surgical emergency, because there are many benign explanations for a pneumoperitoneum. Perhaps the most important maneuver for differentiating between the two is by performing a through history and physical examination. This in conjunction with either a diagnostic peritoneal lavage, contrast studies, or endoscopic evaluation can help prevent a patient from having needless surgery. The causes of a nonsurgical pneumoperitoneum are described as well as a treatment plan for patients presenting with a nonsurgical pneumoperitoneum.

Monitoring of somatosensory evoked potentials: a primer on the intraoperative detection of spinal cord ischemia during aortic reconstructive surgery

The acute interruption of blood supply to the spinal cord during thoracic and thoracoabdominal aortic reconstructions, if unabated, inevitably causes neurological injury secondary to regional hypoxia. Techniques that address the multifactorial nature of spinal cord ischemic injury have evolved to preserve neuromotor function. However, the overall incongruity of the spinal cord's vascular anatomy makes it virtually impossible to predict, with any degree of certainty, the duration of aortic cross-clamping (AXC) that can safely be endured. The sensitivity of evoked potential monitoring to the disruption of spinal cord perfusion has led to the emergence of this modality as an effective tool at the surgeon's disposal for the intraoperative assessment of distal aortic perfusion and cord viability during proximal AXC. Somatosensory evoked potentials (SSEP) provide invaluable diagnostic data as to the status of cord function, through the continuous appraisal of signal amplitude and latency. A latency increase, as small as 10% of the pre-AXC value, is linked to a reduction of spinal cord perfusion pressure and thereby associated with a high incidence of neurological impairment. Four discrete types of SSEP responses have been identified to represent differing surgical scenarios during AXC. The Type I response (deterioration of SSEP within 3 to 5 minutes) is indicative of a failure to maintain a distal pressure of at least 60 mm Hg, whereas a Type II signifies adequate distal aortic perfusion. Sudden loss of signal as witnessed in a Type III SSEP implies compromised critical intercostal vessels and indicates their expeditious reimplantation. A gradual (30 to 50 minutes) SSEP "fadeout" corresponds to marginal distal perfusion, suggesting the presence of extensive pathology. Intraoperative evoked potential monitoring, in conjunction with distal aortic perfusion, permits rapid identification and correction of compromised spinal cord blood flow, permitting repair of aortic lesions without the added liability of time constraints.

Intraoperative adjuncts of spinal cord protection

Immediate neurological deficits as a complication of aortic surgery occur as the direct result of hypoxia, related to the acute deprivation of spinal cord blood supply inflicted by prolonged aortic cross-clamping (AXC). The etiology of spinal cord ischemia constitutes a series of progressive interdependent events which include proximal hypertension, increase in cerebrospinal fluid pressure, perioperative hypotension, inadequate perfusion to critical intercostal or lumbar vessels, extent of aortic pathology and duration of AXC. Several intraoperative interventions and strategies, which address the multifactorial nature of cord injury, are presented by the authors. Of critical importance is the role of adequate distal aortic perfusion, with either left atrium-femoral artery (LA-FA) bypass or arterial-arterial passive shunts, to control both central hypertension, through proximal unloading, and hypotension distal to AXC. Equally crucial is the increase in CSF pressure, secondary to proximal hypertension, which acts antagonistically to distal aortic pressure in regulating spinal cord perfusion pressure (SCPP). Cerebrospinal fluid drainage (CSFD) reduces CSF pressure to offset SCPP to favor cord perfusion. Pharmacological agents, such as papaverine and steroids in combination with CSFD, produce a synergistic benefit of extending the time interval of safe AXC. Encouraging results have also been realized with circulatory arrest and profound hypothermia which reduce oxygen demand of neural tissues and extend the safe duration of AXC interval. The use of distal bypass is most effective with CSFD as an integral component of a multimodality approach, which also incorporates the intraoperative monitoring of somatosensory evoked potentials (SSEP), to detect the onset of spinal cord ischemia and assess the adequacy of distal aortic perfusion and disposition of critical segmental vessels.

Experimental cardiomyopathy as a model of chronic heart failure

End-stage heart disease is a major health care issue and it represents one of the most costly diseases. Several experimental heart failure models have been developed; however, a single model is not widely accepted as representative of clinical heart failure. The doxorubicin-induced cardiomyopathy model was used in the current study to address two issues: 1) to define a standardized dose regimen of intracoronary doxorubicin infusion; and 2) to establish a method of determining the onset and time course of heart failure. Twenty dogs underwent placement of an intracoronary catheter. A total dose of 1 mg/kg of intracoronary doxorubicin was infused. Hemodynamics were obtained at weeks 0, 7, and 12. Echocardiography was performed weekly. Right and left ventricular biopsy specimens were examined at weeks 0 and 12. Survival after doxorubicin-induced cardiomyopathy was 60% at week 12. The development of heart failure was demonstrated by a significant decrease in left ventricular ejection fraction and cardiac index and a significant increase in left ventricular end-diastolic pressure and volume. The leukocyte count, hemoglobin, and hematocrit decreased significantly. Histologic changes of both the right and left ventricular myocardial biopsy specimens included myocellular hypertrophy, loss of myofibrillar material, and vacuolization. Intracoronary doxorubicin reliably produced an experimental model of accelerated heart failure that developed over the course of 12 weeks. Echocardiographic monitoring allowed a close surveillance of heart failure development. This model may be useful to evaluate the efficacy of cardiomyoplasty, mechanical assist devices, transplantation, and reduction ventriculoplasty.

Cardiac binding in experimental heart failure

BACKGROUND

Cardiomyoplasty is a potential therapy for heart failure. Its benefits are attributed to systolic augmentation (dynamic cardiomyoplasty) and prevention of cardiac dilatation (static cardiomyoplasty). To evaluate the static component, we used an artificial membrane for cardiac binding in a canine model of heart failure.

METHODS

Intracoronary doxorubicin was administered weekly for 4 weeks to induce heart failure in 10 dogs, each of which was assigned to one of two treatment groups: (1) no treatment, or (2) cardiac binding. Hemodynamic data were obtained at operation and at 7 weeks after operation. Echocardiography was performed weekly.

RESULTS

Left ventricular end-diastolic pressure and diameter, and right ventricular end-diastolic diameter increased in group 1 (from 9.6 +/- 6.1 to 19.6 +/- 2.3 mm Hg, p = 0.009; from 3.9 +/- 0.4 to 5 +/- 0.3 cm, p = 0.0013; and from 1.6 +/- 0.2 to 1.9 +/- 0.3 cm, p = 0.0036, respectively). Ejection fraction fell in group 1 from 0.60 +/- 0.10 to 0.40 +/- 0.04 (p = 0.0009) and in group 2 from 0.56 +/- 0.02 to 0.40 +/- 0.04 (p = 0.0001), but the difference between groups was not significant.

CONCLUSION

Cardiac binding reduces the ventricular dilatation associated with heart failure without exacerbating left ventricular dysfunction.

Pleural drainage after repair of tetralogy of Fallot

Prolonged pleural effusion after congenital heart surgery results in extended hospitalization. Pleural drainage was evaluated in 39 consecutive patients undergoing repair of tetralogy of Fallot, to identify risk factors for persistent pleural effusion. Duration and amount of drainage was examined by the Kaplan-Meier method and risk factors were evaluated by univariable and multivariable analyses. Median time of pleural drainage was 6.1 days, range 3 to 42 days. Duration of pleural drainage correlated with length of hospital stay (p < 0.0001). Postrepair right atrial pressure (p = 0.018) and preoperative hemoglobin (p = 0.035) were risk factors for persistent drainage. The presence of a previous right thoracotomy reduced drainage duration (p = 0.034). Prolonged mechanical ventilation increased the average daily volume of effusion (p < 0.0001). In conclusion, prolonged pleural effusion is an important morbidity factor after repair of tetralogy of Fallot. Bilateral chest tube insertion is indicated in patients with high preoperative hemoglobin and elevated postrepair right atrial pressure. Right thoracotomy is the preferred surgical approach when a preliminary palliative shunt is required.

Transthoracic intraaortic balloon pump: a simplified technique

A technique of transthoracic intraaortic balloon pump insertion and a clinical experience with 14 patients is reported. The technique of transthoracic intraaortic balloon pump insertion can be done in a rapid and atraumatic fashion. A short prosthetic graft is used, and intraaortic balloon pump removal does not require resternotomy. The technique is a safe alternative in postcardiotomy failure patients with inadequate peripheral arterial access.

Comparative study of biological glues: cryoprecipitate glue, two-component fibrin sealant, and "French" glue

BACKGROUND

Although biological glues have been used clinically in cardiovascular operations, there are no comprehensive comparative studies to help clinicians select one glue over another. In this study we determined the efficacy in controlling suture line and surface bleeding and the biophysical properties of cryoprecipitate glue, two-component fibrin sealant, and "French" glue containing gelatin-resorcinol-formaldehyde-glutaraldehyde (GRFG).

METHODS

Twenty-four dogs underwent a standardized atriotomy and aortotomy; the incisions were closed with interrupted 3-0 polypropylene sutures placed 3 mm apart. All dogs had a 3- by 3-cm area of the anterior wall of the right ventricle abraded until bleeding occurred. The animals were randomly allocated into four groups: in group 1 (n = 6) bleeding from the suture lines and from the epicardium was treated with cryoprecipitate glue; in group 2 (n = 6) bleeding was treated with two-component fibrin sealant; group 3 (n = 6) was treated with GRFG glue; group 4 (n = 6) was the untreated control group. The glues were also evaluated with regard to histomorphology, tensile strength, and virology.

RESULTS

The cryoprecipitate glue and the two-component fibrin sealant glue were equally effective in controlling bleeding from the aortic and atrial suture lines. Although the GRFG glue slowed bleeding significantly at both sites compared to baseline, it did not provide total control. The control group required additional sutures to control bleeding. The cryoprecipitate glue and the two-component fibrin sealant provided a satisfactory clot in 3 to 4 seconds on the epicardium, whereas the GRFG glue generated a poor clot. There were minimal adhesions in the subpericardial space in the cryoprecipitate and the two-component fibrin sealant groups, whereas moderate-to-dense adhesions were present in the GRFG glue group at 6 weeks. The two-component fibrin sealant was completely reabsorbed by 10 days, but cryoprecipitate and GRFG glues were still present. On histologic examination, both fibrin glues exhibited minimal tissue reaction; in contrast, extensive fibroblastic proliferation was caused by the GRFG glue. The two-component and GRFG glues had outstanding adhesive property; in contrast, the cryoprecipitate glue did not show any adhesive power. The GRFG glue had a significantly greater tensile strength than the two-component fibrin sealant. Random samples from both cryoprecipitate and the two-component fibrin glue were free of hepatitis and retrovirus.

CONCLUSIONS

The GRFG glue should be used as a tissue reinforcer; the two-component fibrin sealer is preferable when hemostatic action must be accompanied with mechanical barrier; and finally, the cryoprecipitate glue can be used when hemostatic action is the only requirement.

Thoracic Surgery Workforce Report. The fourth report of the Thoracic Surgery Workforce Committee of The American Association for Thoracic Surgery and The Society of Thoracic Surgeons

To determine demographics, practice patterns, and work volume of North American thoracic surgeons, we sent a detailed survey to all members of The American Association for Thoracic Surgery and The Society of Thoracic Surgeons between January and May 1993 to determine data for 1992; 3049 of 3487 (87%) thoracic surgeons responded and 2677 (88%) were in active practice. Ninety-seven percent were male and 3% female, with a mean age of 52 years. Sixty-five percent considered fee-for-service as their primary compensation mode. Only 24% do isolated subspecialty work: 2% pediatric cardiac surgery. 10% general thoracic surgery, and 12% adult cardiac surgery. Seventy-six percent of respondents do both cardiac and thoracic operations. Workload data for adult cardiac, pediatric cardiac, general thoracic, peripheral vascular, and pacemaker operations were requested. Volume data were cross-correlated with age, 10 geographic regions including Canada, type of practice, and type of compensation and were cross-checked by hospital discharge data for 1992. These data were compared with data from similar surveys performed in 1976, 1980, and 1985, under the auspices of the same two societies; these latter surveys used diplomates of the American Board of Thoracic Surgery as their database. Workloads have increased over previous surveys. Most surgeons do a wide variety of thoracic operations, and exclusive designations are in the minority.

The effects of nitric oxide inhibition on regional hemodynamics during hyperdynamic endotoxemia

OBJECTIVE

To determine the effect of the inhibition of nitric oxide (NO) on selective organ blood flow in endotoxin-induced sepsis.

DESIGN

Nonrandomized, controlled experiment.

SETTING

Animal research facility in Brooklyn, NY.

PARTICIPANTS

Eleven mongrel dogs.

INTERVENTION

Eleven dogs were divided into one of two groups: a control group (n = 5) and an endotoxin-treated group (n = 6). The animals were anesthetized, and electromagnetic and ultrasonic flow probes were placed on the distal aorta, right internal carotid artery, superior mesenteric artery, and left renal artery. Sepsis was induced with a 60-mg/kg intravenous injection of Escherichia coli endotoxin. When the arterial blood pressure decreased to less than 60 mm Hg despite adequate fluid resuscitation, NO synthesis was inhibited with a 25-mg/kg intravenous administration of NG-monomethyl-L-arginine. After 15 minutes of inhibition, a 400-mg/kg intravenous administration of L-arginine, the substrate of NO synthase enzyme, was given. Physiologic measurements were continued for 15 minutes thereafter.

MAIN OUTCOME MEASURES

Heart rate, blood pressure, central venous pressure, pulmonary artery pressure, pulmonary capillary wedge pressure, cardiac output, hematocrit, arterial and venous blood gas values, and blood flow measurements of right internal carotid artery, superior mesenteric artery, left renal artery, and distal aorta.

RESULTS

Control animals did not demonstrate a significant (P > .05) decrease in blood flow in the internal carotid artery, superior mesenteric artery, and distal aorta after the administration of NG-monomethyl-L-arginine. The endotoxin-treated group showed a significant (P < .05) decrease in organ perfusion when treated with the NO synthase inhibitor, NG-monomethyl-L-arginine.

CONCLUSIONS

Inhibition of NO production in the treatment of sepsis caused a significant decrease in blood flow to all vascular beds in vivo. The role, if any, of the inhibition of NO in the treatment of sepsis is questioned.

Effect of cerebrospinal fluid drainage and/or partial exsanguination on tolerance to prolonged aortic cross-clamping

Paraplegia as a consequence of spinal cord ischemia associated with procedures on the thoracic and thoracoabdominal aorta has been linked to the interaction of proximal hypertension with elevated cerebrospinal fluid pressure (CSFP) during aortic cross-clamping (AXC). CSFP reduction via cerebrospinal fluid (CSF) drainage is thought to significantly prolong the cord's tolerance to AXC. Likewise, partial exsanguination is reported to effectively reduce ischemic injury by controlling proximal hypertension. To evaluate the individual and collective efficacy of both techniques, 18 mongrel dogs (25 to 35 kg), divided into three equal groups, underwent a fourth interspace left thoracotomy AXC. Baseline proximal arterial blood pressure (PABP), distal arterial blood pressure (DABP), and CSFP were established and monitored at 5-minute intervals during 120 minutes of AXC, and for 30 minutes thereafter. Group I animals were partially exsanguinated prior to AXC to maintain PABP at a mean of 115 to 120 mmHg. Group II animals had sufficient (16 +/- 5 cc) CSF withdrawn to maintain a DABP-CSFP gradient, i.e., spinal cord perfusion pressure (SCPP) of 20 mmHg. Group III animals were treated with both CSF drainage and partial exsanguination in the same manner as groups I and II, respectively. Perioperative somatosensory evoked potential (SEP) monitoring evaluated cord function. Postoperative neurological outcome was assessed with Tarlov's criteria. SEPs degenerated approximately 22 minutes following AXC for groups II and III. In contrast, group I exhibited rapid (10 +/- 7 min) SEP loss. All five surviving group I animals displayed paralysis 48 hours postoperatively.(ABSTRACT TRUNCATED AT 250 WORDS)

Nitric oxide inhibition in the treatment of the sepsis syndrome is detrimental to tissue oxygenation

The manifestations of the septic syndrome are thought to be mediated by cytokines through their role in the production of nitric oxide (NO). It is hypothesized that the inhibition of NO production with an inhibitor such as NG-monomethyl-L-arginine (L-NMMA) may be beneficial in the treatment of septic shock. Sepsis was induced by the intravenous administration of Escherichia coli endotoxin (60 micrograms/kg) in six conditioned mongrel dogs (20-24 kg). Mean arterial pressure (MAP), heart rate (HR), central venous pressure (CVP), and pulmonary artery pressure (PAP) were continuously monitored. Cardiac output (CO), pulmonary capillary wedge pressure (PCWP), and arterial and mixed venous blood gases were obtained every 10 min. When the MAP decreased below 60 mm Hg, NO inhibitor L-NMMA was given by intravenous injection (25 mg/kg). Physiologic parameters were then measured at 2 and 5 min after L-NMMA injection. Subsequently, L-arginine (400 mg/kg), the substrate for the NO synthase enzyme, was administered and measurements were repeated at similar intervals. L-NMMA in septic canines produced a significant increase in MAP and SVR with a significant decrease in CO and tissue oxygenation (DO2 and VO2). These changes were reversed with the administration of L-arginine. There were no significant differences in the PCWP, CVP, PAP, or HR throughout the entire study. These results suggest that the inhibition of NO production by L-NMMA in a septic model produces elevated MAP and SVR at the expense of tissue oxygenation. Thus, its use, as a principal means of therapy for the septic syndrome, may not be appropriate because of detrimental effects on tissue oxygenation.

Outcome of patients with abnormal ocular pneumoplethysmographic measurements undergoing coronary artery bypass grafting

A total of 1780 patients without symptoms of cerebral ischemia undergoing coronary artery bypass grafting (CABG) were screened before surgery for carotid stenosis by pneumophlethysmography. An abnormal test was defined as a difference in ophthalmic artery pressures of > or = 5 mmHg or ophthalmic-brachial pressure index < or = 0.69. Some 99 patients (5.6%) had an abnormal ocular pneumoplethysmographic measurement (89 unilateral, ten bilateral). Of these, 26 patients underwent prophylactic carotid endarterectomy before CABG (group 1), while the remaining 73 patients had reconstruction without previous carotid endarterectomy (group 2). A total of 100 patients (group 3) with normal ocular pneumoplethysmographic results were used as controls. The three groups were comparable with respect to age, diabetes, hypertension, smoking and severity of coronary artery disease. Early (30-day) postoperative stroke rates were 0 and 4% (n = 3) for groups 1 and 2 respectively, and 0% for group 3 (P > 0.07). Early mortality rates after CABG for groups 1 and 2 were 4% (n = 1) and 1% (n = 1), respectively and 2% (n = 2) for groups 3 (P > 0.4). Late follow-up (mean 48 months) demonstrated stroke rates of 0% for group 1, and 10% and 4% for groups 2 and 3 (P > 0.08). The early mortality and stroke rates in the ten patients with bilateral abnormal ocular pneumoplethysmographic values were 0 and 0%. However, late strokes occurred significantly more often (43%) in patients with bilateral abnormal results compared with those with unilateral abnormal findings when both groups did not undergo carotid endarterectomy (P < 0.04).(ABSTRACT TRUNCATED AT 250 WORDS)

Lipomatous hypertrophy of the interatrial septum

Lipomatous hypertrophy of the interatrial septum, a finding associated with obesity and advancing age, consists of accumulation of adipose tissue including fetal adipose tissue in the interatrial septum. It is a rare lesion of the heart and can reach notable size. A case is reported in which the diagnosis of lipomatous hypertrophy of the interatrial septum was established intraoperatively; the large bulk of the lipoma was such that it required major reconstruction of the interatrial septum and right and left atrial walls.

Dynamic cardiomyoplasty: left ventricular diastolic compliance at different skeletal muscle tensions

The possible limitation of left ventricular (LV) relaxation during diastole is a concern for clinicians and researchers utilizing dynamic cardiomyoplasty. This study was designed to evaluate the LV compliance at three different skeletal muscle tensions, in a normal heart and in a failing heart, created by propranolol infusion (11.6 mg/kg). A biventricular latissimus dorsi muscle (LDM) wrap was performed in 10 dogs. The LV pressure (Millar) and two minor axis dimensions (endocardial crystals) were measured. LV pressure-volume loops were constructed, and LV diastolic compliance was calculated. The measurements were obtained before wrap and after wrap at different LDM tensions with 0, 5, and 10 volts stimulation each time. These measurements were repeated after propranolol treatment. The results showed that LV diastolic compliance (dV/dP) was 1.79 before wrap and about 0.7 after wrap, and after propranolol, at various tensions and stimulations. LDM wrap decreased LV compliance significantly. LV compliance was not significantly affected by changing tension or voltage of stimulation in either the failing or the non-failing heart. The reduction in compliance may be an indication that LDM wrap causes a limitation of LV relaxation, which is one of wrap's deleterious effects.

Acute mesenteric ischemia after cardiopulmonary bypass

Three thousand sixty-six patients underwent cardiopulmonary bypass at the Maimonides Medical Center over a 5-year period from January 1, 1987, to January 1, 1992. Of these patients, 1,890 (62%) were less than 70 years of age, 969 (32%) ranged from 70 to 79 years of age, and 207 (7%) were 80 years of age or older. The overall 30-day mortality rate was 8%. Eleven patients developed acute mesenteric ischemia from 24 hours to 12 days postoperatively. At the time of diagnosis, the majority of patients presented with late classical signs and symptoms of acute mesenteric ischemia including abdominal distension, respiratory distress, hypotension, oliguria, and sepsis. All patients underwent immediate laparotomy. Extensive bowel necrosis was found in all, and resection was possible in eight patients. All patients died as a result of this complication. Using the exact trend test, we found a statistically significant increase in the incidence of deaths due to acute mesenteric ischemia after cardiopulmonary bypass in older compared with younger patients. This fatal complication after cardiopulmonary bypass occurs more often than previously believed and is a relatively common cause of death in the elderly.

One-year monkey heart xenograft survival in cyclosporine-treated baboons. Suppression of the xenoantibody response with total-lymphoid irradiation

The shortage of cadaveric human organs for transplantation could be alleviated by the use of xenografts. Long-term (> one-year) survival of xenografts in humans or experimental animals has not been achieved with previous immunosuppressive protocols. Poor results in xenotransplantation compared with allotransplantation have been attributed to a more potent antibody response rather than to cell-mediated responses. To investigate these issues a concordant heterotopic cardiac xenograft model was developed in conjunction with cyclosporine and/or total-lymphoid irradiation. Concordant models permit examination of xenoantigen induced antibody and cell-mediated responses since preformed humoral factors (in discordant models) do not cause hyperacute rejection. Four groups of baboon recipients received cervical heart transplants from cynomolgous monkeys. Group I (n = 2), untreated, mean survival (MS) = 6 days; group II (n = 5), CsA and methylprednisolone, MS = 25 days; group III (n = 3), preoperative TLI, MS = 29 days; group IV (n = 6), preoperative TLI and CsA+MP, MS = 255 days (> 77, > 108, > 142, 184, > 480, 540 days). Heart xenografts of CsA-MP-treated recipients appear to be destroyed predominantly by antibody (IgM)-mediated processes whereas cell-mediated rejection is likely the major reaction in TLI-treated recipients. CsA-MP-treated recipients had early immunohistochemical evidence of antibody and complement-mediated rejection (deposition of IgM and complement but not IgG on heart xenografts). In contrast IgM and complement deposits were not detected on heart xenografts in TLI- and TLI-CsA-treated recipients. IgG xenoantibodies were only detected on the two rejected heart grafts of TLI-CsA-treated recipients. CsA-MP-treated recipients rapidly developed high xenoantibody titers (1:256 to 1:512) that immediately preceded rejection. In contrast, TLI-treated animals developed lower levels of xenoantibody (< or = 1:8) and TLI-CsA-treated recipients had no detectable xenoantibody during the initial three months after transplantation (and titers no greater than 1:8 thereafter.) The lack of xenoantibody was likely not due to a generalized inhibitory effect of the immunosuppressants on B cell function since all classes of serum immunoglobulins were in the normal range. Intragraft cytolytic lymphocyte activity was detected in rejecting TLI- and TLI-CsA-treated recipients but could not be detected in xenografts of CsA-MP-treated recipients. One explanation for these data is that TLI (either directly or indirectly) induces a state of specific B cell unresponsiveness to monkey xenoantigens, thereby preventing IgM mediated rejection in the third week after transplantation.(ABSTRACT TRUNCATED AT 400 WORDS)

Intrathecal perfusion of an oxygenated perfluorocarbon prevents paraplegia after aortic occlusion

A canine model was used to evaluate the effects of continuous intrathecal perfusion of an oxygenated perfluorocarbon emulsion on systemic and cerebral hemodynamics and neurologic outcome after 70 minutes of normothermic aortic occlusion. Twelve mongrel dogs were instrumented to monitor proximal and distal arterial blood pressure, cerebrospinal fluid pressure, spinal cord perfusion pressure, and somatosensory evoked potentials. The intrathecal perfusion apparatus consisted of two perfusing catheters, placed in the intrathecal space through a laminectomy, and a draining catheter percutaneously inserted in the cisterna cerebellomedullaris. The aorta was cross-clamped just distal to the left subclavian artery for 70 minutes. Animals were randomized into two groups: group 1 (n = 6) animals were treated with intrathecal perfusion of saline solution, whereas group 2 (n = 6) animals received oxygenated Fluosol-DA 20%. Data were acquired at baseline, during the cross-clamp period, and after reperfusion. Normothermic Fluosol or saline solution was infused at a rate of 15 mL/min beginning 15 minutes before cross-clamping and continued throughout the ischemic interval. There was no difference in proximal arterial blood pressure (97.2 versus 95.4 mm Hg; p > 0.05) or distal arterial blood pressure (14.6 versus 15.0; p > 0.05) between the two groups throughout the cross-clamp interval. Cerebrospinal fluid pressure rose significantly in both groups with the onset of intrathecal perfusion of either saline solution or Fluosol (7 +/- 1 versus 24 +/- 5 and 8 +/- 1 versus 40 +/- 4 mm Hg, respectively; p < 0.05). The rise in cerebrospinal fluid pressure was sustained throughout the perfusion interval in both groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Internal mammary artery bypass: thirteen years of experience. Influence of angina and survival in 5125 patients

Internal mammary artery (IMA) bypass to the anterior descending coronary artery (ADA) was performed in 5125 patients from January 1978 to December 1990. The average age of patients was 68 years; males accounted for 68% (3485 patients) and 82% (4203) were NYHA Class III. Left ventricular function was impaired (ejection fraction < 40%) in 68% (3485 patients). The average number of additional saphenous vein graft (SVG) per patient was 2.2. Operative mortality was 1.8%. Mediastinitis occurred in 51 patients (1.0%). Reoperation for bleeding was necessary in 56 patients (1.1%). Perioperative myocardial infarction was seen in 102 patients (2.0%) and neurological complications occurred in 51 patients (1%). Repeat coronary angiography was performed in 1414 patients (28%) and demonstrated a patency rate of 96% in IMA grafts and 75% in SVG grafts (p < 0.001). Survival at 13 years was 80% from all causes and 90% when non-cardiac deaths were excluded. Recurrence of angina occurred in 768 patients (15%) and reoperation or PTCA was performed in 61 (1.2%). During the same time period, 2345 patients underwent coronary artery bypass utilizing solely SVG. Survival at 13 years was 68% from all causes and 78% when non-cardiac deaths were excluded (p < 0.001). Recurrent angina was present in 727 patients (31%) (< 0.001). This data suggests that long-term probability of cumulative survival and occlusion free survival were significantly greater and the probability of recurrent angina and reoperative CABG and death from cardiac causes were significantly less in the IMA patients and should be the conduit of choice in coronary bypass surgery.

Effects of exsanguination and sodium nitroprusside on compliance of the spinal canal during aortic occlusion

To evaluate the effects of sodium nitroprusside (SNP) and partial exsanguination (EXS) on systemic hemodynamics and cerebrospinal fluid dynamics, we monitored proximal and distal blood pressure (BP), cerebrospinal fluid pressure (CSFP), spinal cord perfusion pressure (SCPP), and compliance of the spinal canal (CSC) in 10 mongrel dogs during aortic cross-clamping of the descending thoracic aorta. CSC was measured by serial injections of 2 ml of saline solution into the cisterna cerebellomedullaris via a percutaneously placed catheter with simultaneous measurements of CSFP. Data were acquired at baseline (BL), during aortic cross-clamping with proximal hypertension (AXC), and after control of proximal hypertension with EXS and SNP. During the cross-clamp interval, mean proximal aortic pressure (PxBP) rose from 114 +/- 6 to 150 +/- 3 mm Hg (P less than 0.001), whereas mean blood pressure decreased to 88 +/- 5 and 82 +/- 4 mm Hg during the SNP and EXS intervals, respectively (P less than 0.05 vs BL). EXS and SNP were equally effective in controlling PxBP (82 +/- 4 vs 88 +/- 5 mm Hg, P greater than 0.05). Mean distal aortic pressure (DsBP) decreased from systemic values to 21.5 +/- 1.9 mm Hg during AXC, and to 12.4 +/- 1.0 and to 8 +/- 0.8 mm Hg during EXS and SNP, respectively (P less than 0.05 AXC vs EXS and SNP). SNP lowered DsBP significantly more than EXS, 8 +/- 0.8 vs 12.4 +/- 1.0 mm Hg (P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Aortoventriculoplasty in the management of an infected Cabrol graft

This report describes use of a modified aortoventriculoplasty (Konno procedure) for reoperation on a patient with prosthetic aortic valve conduit endocarditis. The modified Konno procedure was necessary to expose the mid-left ventricular outflow tract to reconstruct an aortic annulus.

A multimodality approach lengthens warm ischemic time during aortic cross-clamping

To evaluate the effects of exsanguination, cerebrospinal fluid drainage (CSFD), steroids alone and in conjunction with CSFD on spinal cord perfusion pressure (SCPP), and neurological outcome following 70 min of normothermic spinal cord ischemia, we monitored proximal (Px BP) and distal (Ds BP) aortic blood pressure, cerebrospinal fluid pressure, and somatosensory evoked potentials (SEP) in 29 mongrel dogs. In all animals Px BP during aortic cross-clamping was controlled with partial exsanguination (40-50% circulating blood volume). Dogs were randomized into four groups (gp): gp 1 (n = 6) control; gp 2 (n = 8) steroids only (methylprednisolone 30 mg/Kg 10 min before aortic occlusion and 4 hr later); gp 3 (n = 8) CSFD only; gp 4 (n = 7) steroids and CSFD. Partial exsanguination effectively controlled Px BP during aortic cross-clamping in all groups. After the statistically significant decrease from preclamp values, mean Px BP did not differ among groups (78.9, 81.2, 80.5, and 80.3 mm Hg, respectively, P greater than 0.05). Mean Ds BP decreased from systemic values to 12.6, 16.8, 16.7, and 17 mm Hg, respectively, after aortic occlusion (P less than 0.05); these values did not differ from one another. CSFP did not change significantly from its baseline value while the aorta was cross-clamped in gp 1; CSFP was significantly reduced to 6.2 mm Hg in gp 2, steroid-treated animals (P less than 0.05 vs gp 1); a further significant reduction in CSFP was noted in gp 3 and 4 undergoing CSFD (0.07 and 0.67 mm Hg, respectively, P less than 0.05 vs gp 1 and 2).(ABSTRACT TRUNCATED AT 250 WORDS)

Successful repair of a submitral left ventricular infected pseudoaneurysm

Aneurysms of the left ventricle may be congenital or may occur after a myocardial infarction, trauma, or endocarditis. Infective endocarditis can cause destructive injury to the heart in various ways. This report describes the formation of an aneurysm of the left ventricle from trauma of a bacterial vegetation of the mitral valve. Early recognition by echocardiography and magnetic resonance imaging led to successful repair and prevented a catastrophic result.

Mycotic aneurysm of the aortic arch with aortoesophageal fistula

An elderly man presented with an aortoesophageal fistula (AEF) and underwent resection of a mycotic aneurysm of the aortic arch. After an initial success, the patient ultimately succumbed to mediastinal sepsis. The various approaches to combined aortic and esophageal pathology are presented with the recommendation for aortic replacement along with early removal of mediastinal contamination.

Successful cardiac xenogeneic transplantation in primates using total lymphoid irradiation

Combined total lymphoid irradiation (TLI) and cyclosporine (CyA) dramatically prolong cardiac xenografts in small animals. In order to evaluate this immunosuppressive regimen in primates, heterotopic cardiac cervical xenografts were implanted in a monkey-to-baboon model. The following groups evolved: group 1 (n = 2) control, no immunosuppression; group 2 (n = 4) CyA and steroids; group 3 (n = 2) preoperative TLI (800 rad total); group 4 (n = 4) TLI combined with CyA and steroids as in groups 2 and 3. Complement-dependent cytotoxicity, mixed lymphocyte culture, cell mediated cytotoxicity as well as myocardial biopsies were periodically monitored. A Muga scan was performed at 1 year posttransplant to assess ventricular function. Cardiac xenograft survival was best in group 4 animals (108, 184, 480, 540 days) compared with 5 and 7 days in the control group. In group 2, graft survival was 13, 17, 18 and 63 days. TLI alone prolonged survival up to 28 and 29 days. Hemorrhage and myocyte necrosis were seen in all rejected grafts of group 1, 2 and 3 animals. Mononuclear cell infiltrate and fibrosis were present in group 4 grafts at rejection. High antibody titers (1:256 to 1:512) were detected at rejection only in group 1, 2 and 3 animals. This suggests that the combined use of TLI and CyA substantially prolongs xenograft survival in a primate model by preventing early antibody-mediated rejection as well as by limiting cellular response.

Efficacy of right atrial infusion of PGE1 in sepsis-induced pulmonary hypertension

In this study we investigated the effects of right atrial infusion of PGE1 (RAIPGE1) in doses from 40 to 500 ng/kg/min on sepsis-induced pulmonary artery hypertension (SIPAH). Thirteen pigs were randomized into a time-course group (n = 6) and a PGE1-treated group (n = 7). Pulmonary hypertension (PAH) was induced with the infusion of Pseudomonas Aeruginosa (PsAr) at a concentration of 2 X 10(8) CFU/20 kg/min in both groups. The infusion of PsAr caused a significant and persistent rise in mean pulmonary artery pressure (MPA), pulmonary vascular resistance (PVRI), right ventricular compliance (RVC), RV dp/dt, and right ventricular stroke work index (RVSWI), 30 min after the onset of infusion (P less than 0.05 vs baseline). Systemic hemodynamics and gas exchange were not affected throughout the 3-hr period of infusion (P = NS); however, left ventricular compliance (LVC) was depressed at a MPA greater than 35 mm Hg. The RAIPGE1 following SIPAH caused a concentration-dependent reduction above 40 ng/kg/min of MPA, PVRI, RVSWI, and RV dp/dt (P less than 0.05, 120 and 500 ng/kg/min vs PAH). RVC returned to baseline values during the infusion of PGE1. Systemic hemodynamics, including oxygen delivery and extraction, were unaffected by the infusion of PGE1, but LVC was improved (P less than 0.05, PGE1 500 vs PAH). The infusion of PGE1 caused a concentration-dependent rise in shunt fraction (Qs/Qt) and alveolararterial oxygen gradients which reached statistical significance during the infusion of 500 ng/kg/min. Our data show that RAIPGE1 is effective in ameliorating RV and pulmonary hemodynamics, but at the largest dose it negatively affects gas exchange.

Cerebrospinal fluid drainage and steroids provide better spinal cord protection during aortic cross-clamping than does either treatment alone

We investigated whether intravenous methylprednisolone (30 mg/kg) before 30 minutes of aortic cross-clamping and after 4 hours could enhance the effects of cerebrospinal fluid drainage on spinal cord perfusion pressure and postoperative paraplegia when proximal blood pressure was controlled with sodium nitroprusside and partial exsanguination. Dogs were randomized into three groups: group 1 (n = 6), control; group 2 (n = 7), steroids; and group 3 (n = 6), steroids with cerebrospinal fluid drainage. During aortic cross-clamping, blood pressure proximal to the clamp decreased significantly in each group compared with baseline (p less than 0.05), but did not differ among groups (group 1 = 82.2, group 2 = 82.1, group 3 = 86.6 mm Hg, p greater than 0.05). Mean distal pressure decreased from systemic values to 8.4, 8.5, and 3.7 mm Hg, respectively, after aortic cross-clamping (p less than 0.05); these values did not differ from one another (p greater than 0.05). During aortic cross-clamping, cerebrospinal fluid pressure in groups 1 and 2 did not differ significantly compared with baseline (12.2 versus 8.2, 14.2 versus 10.7 mm Hg, p greater than 0.05), whereas in group 3 the baseline cerebral spinal fluid pressure of 10.7 mm Hg decreased to 0.4 mm Hg (p less than 0.05). Spinal cord perfusion pressure in group 3 was significantly higher than in groups 1 and 2 (3.3 versus -3.9 and -5.7 mm Hg, p less than 0.05), but did not differ between groups 1 and 2 (p greater than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Influences of laser pulse duration and anastomotic disruption on laser-assisted microvascular anastomoses (LAMA)

The success rate of laser-assisted microvascular anastomosis (LAMA) can be influenced by many factors, including the parameters of the laser technique used. This study examined the effects of laser pulse duration and the occurrence of anastomotic disruption immediately following first repair attempts on the incidence of aneurysm formation and the patency rate in LAMA. Fifty transected rat femoral arteries in 25 rats were anastomosed with three stay sutures and welded with a CO2 laser at a power of 80 mW. In each rat, the laser was applied in the form of 45 pulses of 0.2 sec duration to one femoral artery (group 1) and in the form of 15 pulses of 0.6 sec duration to the contralateral femoral artery (group 2). Comparison of group 1 with group 2 showed that overall rates of aneurysm formation (30% vs. 17%) and patency rates (92% vs. 96%) did not differ significantly (P less than 0.05) at 3 weeks postoperatively. However, disrupted vessels in both groups had a significantly higher incidence of subsequent aneurysm formation than nondisrupted vessels (54% vs. 0% in group 1, P less than 0.05; 43% vs. 6% in group 2, P less than 0.06; groups 1 and 2 pooled, P less than 0.001). These findings indicate that changes in laser pulse duration such as those tested do not affect the aneurysm and patency rates of LAMA. The results demonstrate, however, that disruption after laser welding plays a significant role in subsequent aneurysm formation.

Demographic changes in coronary artery bypass surgery and its effect on mortality and morbidity

Over the past 4-5 years, possibly with the advent of percutaneous transluminal coronary angioplasty (PTCA), there has been a changing patient population for coronary artery bypass surgery (CABS) with a gradual increase in the operative mortality. In an attempt to analyze the changing demographics in patients undergoing CABS and its effect on operative mortality, we analyzed data from 5536 consecutive patients undergoing isolated CABS. There was 4151 patients less than 70 years of age and 1385 patients greater than 70 years. Reoperative CABS procedures were performed in 385 patients, and CABS for post infarction unstable angina pectoris was performed in 578 patients. During the same time period, 2910 patients underwent PTCA. The mean age of bypass patients was 68.5 years with 38% being 70 years or older. The left ventricular ejection fraction in patients undergoing CABS averaged 38%. The average number of bypasses performed was 3.1. In comparison, patients presenting for PTCA were younger (average age 55), had normal ejection fractions (average 55%) and were predominantly treated for single or double vessel disease. The hospital mortality for elective CABS in patients less than 70 years of age was 1.8%, for reoperative CABS 3.6%, for post infarction unstable angina pectoris 4%, and for patients greater than 70 years 8%, for a combined operative mortality of 4.8%. These data suggest that because of the increasing number of elderly patients (greater than 70 years of age), and the increasing number of reoperative CABS cases and acute myocardial infarction patients with unstable angina pectoris presenting for CABS, the operative mortality will continue to rise.