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Biomedical subjects

J N Cunningham

Publications and source records attributed to J N Cunningham.

At least 55 records · Page 3Linked to original sources
PubMed1991

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.

Adolescent↗
PubMed1991

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.

Animals↗
PubMed1991

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.

Aged↗
PubMed1990

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.

Anastomosis, Surgical↗
PubMed1990

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)

Animals↗
PubMed1990

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.

Alprostadil↗
PubMed1990

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.

Adult↗
PubMed1989

Internal mammary artery bypass grafting: influence on recurrent angina and survival in 2,100 patients.

Internal mammary artery (IMA) bypass grafting to the anterior descending coronary artery was performed in 2,100 patients between January 1978 and July 1986. The average number of additional saphenous vein grafts (SVGs) per patient was 1.8. During the same period, 1,753 patients underwent coronary artery bypass grafting using an SVG (average number of grafts per patient, 3.2). The average patient age was similar: 62.3 years for IMA grafts and 64.7 years for SVGs. Men constituted two thirds of each group. Left ventricular function was impaired (ejection fraction less than 45%) in 1,071 (51%) of IMA grafts and 847 (48.3%) of SVGs. Other aggregate risk factors, ie, elevated blood pressure, diabetes mellitus, previous myocardial infarction, and congestive heart failure, were similar in each group. Operative results and postoperative mortality of the IMA and SVG patients were comparable. However, the long-term probability of cumulative survival and occlusion-free survival were significantly greater and the probability of recurrent angina and reoperative coronary artery bypass grafting were significantly less in IMA graft patients (p less than 0.015). The relative risk of occlusion in an SVG was 4 to 5 times greater than that of the IMA graft. These data indicate that a patent IMA graft to the anterior descending coronary artery protects against recurrent angina and death from cardiac-related causes, and that the IMA should be the conduit of choice.

Adult↗
PubMed1989

Technique and results with a roller pump left and right heart assist device.

During the last 10 years we have inserted a roller pump-driven left heart assist device in 72 patients and a right heart assist device in 7 patients for profound heart failure after a variety of cardiac surgical procedures. In addition a percutaneous left heart assist device (transseptal insertion of left atrial cannula via a femoral vein) was employed in 5 patients with profound cardiogenic shock after acute myocardial infarction. Thirty patients (41.7%) were weaned from the left heart assist device and 21 (29.2%) were discharged from the hospital. Two patients (40.0%) were weaned from the right heart assist device, but both later died during the postoperative period. Of the 5 patients in whom a percutaneous left heart assist device was inserted, 4 underwent successful emergency percutaneous transluminal coronary angioplasty, but all 5 patients died. Causes of death included severe coagulopathy, irreversible extensive myocardial infarction and cardiac failure, refractory arrhythmias, severe "shock" lung, and multisystem failure. In summary, satisfactory results can be achieved with a roller pump-driven left and right heart assist device for severe postoperative heart failure. Further experience should be obtained with the percutaneous technique to assess its efficacy in treating patients with acute myocardial infarction and cardiogenic shock.

Assisted Circulation↗
PubMed1989

Effect of sodium nitroprusside on spinal cord perfusion and paraplegia during aortic cross-clamping.

To evaluate the effects of sodium nitroprusside (SNP) on hemodynamics, cerebrospinal fluid dynamics, and neurological outcome after 30 minutes of thoracic aortic occlusion, we monitored proximal and distal blood pressure, cerebrospinal fluid pressure, spinal cord blood flow, and somatosensory evoked potentials. In group 1 (n = 6), no attempts were made to control proximal hypertension, whereas in group 2 (n = 6), proximal blood pressure was controlled with intravenous infusion of SNP. There was no significant difference in proximal or distal blood pressure or cerebrospinal fluid pressure between the two groups at baseline. During the crossclamp interval, the mean proximal aortic pressure rose from 108 +/- 21 to 146 +/- 14 mm Hg (p less than 0.001) in the control group, whereas the mean blood pressure in the SNP group was maintained at 99.8 +/- 12 mm Hg (p = not significant compared with baseline blood pressure). Mean distal aortic pressure decreased from systemic values to 23 +/- 7 mm Hg in control animals and to 11 +/- 5 mm Hg in the SNP group (p less than 0.005). In the latter group, cerebrospinal fluid pressure increased significantly from 10.6 +/- 1.9 to 20.1 +/- 5.5 mm Hg (p less than 0.005). In animals receiving SNP, spinal cord blood flow was decreased in the lower spinal cord segments and increased in the upper cord segments. When compared with controls, this difference did not reach significance.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Internal mammary artery bypass: effect on longevity and recurrent angina pectoris in 2900 patients.

Internal mammary artery bypass (IMA) to the anterior descending coronary artery was performed in 2900 patients from January 1978 to December 1987. The average age of the patients was 64 years. Males accounted for 68% (1972 patients) and 82% (2378 patients) were in New York Heart Association (NYHA) class III. Left ventricular function was impaired in 51%. The average number of additional saphenous vein grafts per patient was 1.8. The operative mortality was 1.6%. Mediastinitis occurred in 29 patients (1%). Reoperation for bleeding was necessary in 32 patients (1.1%). Perioperative myocardial infarction (MI) was seen in 58 patients (2%) and neurological complications occurred in 32 patients (1.1%). Repeat coronary angiography was performed in 703 patients (25%) and demonstrated a patency rate of 96% in IMA grafts and 81% in saphenous vein grafts (SVG). Survival at 9 years was 90% from all causes and 95% when noncardiac deaths were excluded. Recurrence of angina occurred in 522 patients (18%) and reoperation was performed in 15 patients (0.5%). During the same time period, 1783 patients underwent coronary artery bypass utilizing a SVG. Survival at 9 years was 78% from all causes and 83% when noncardiac deaths were excluded. Recurrent angina was present in 546 patients (39%). These data suggest that a patent-IMA to the anterior descending protects against recurrent angina and death from cardiac causes and should be the conduit of choice.

Angina Pectoris↗
PubMed1989

Effect of sternotomy and coronary bypass surgery on postoperative pulmonary mechanics. Comparison of internal mammary and saphenous vein bypass grafts.

Coronary artery bypass grafting (CABG) is commonly performed via a median sternotomy with a reversed saphenous vein (SV) and/or an internal mammary artery (IMA) graft. Sternotomy and IMA harvesting may adversely affect postoperative respiratory function (PFTs) as disruption of the sternun may impair chest wall stability, and the decrease in intercostal muscle blood supply after removal of the IMA may reduce the force of respiration. We compared preoperative and six- to eight-week postoperative PFTs in patients undergoing CABG. The results were independent of age, sex, number of grafts, aortic cross clamp time, duration of bypass run, and postbypass fluid gradient. It was concluded that sternotomy caused a decrease in postoperative PFTs and that IMA harvesting may be accompanied by greater impairment in PFTs than when SV grafts alone were used.

Aged↗
PubMed1988

Effect of blood bonding on bursting strength of laser-assisted microvascular anastomoses.

This experiment evaluated the influence of blood on the weld strength of laser-assisted microvascular anastomoses (LAMA). Rat femoral arteries were anastomosed end-to-end by either direct laser welding (group I) or by a blood-bonded technique (group II) whereby fresh blood was applied to the vessel edges before laser exposure. Bursting strength was measured at 0, 1, and 24 hours and at 3 and 7 days by infusing methylene blue into the vessel while pressure was monitored. The results showed significantly increased bursting strength in group II compared with group I at 0 hour and 7 days (P less than 0.05). There was a significant increase in bursting strength in group I from 0 hour to 1 hour (P less than 0.05). It is concluded that blood-bonding enhances the early bursting strength of LAMAs and may facilitate arterial wall healing.

Anastomosis, Surgical↗
PubMed1988

Pulmonary complications of a roller pump right ventricular assist device.

The pulmonary effects of a right ventricular assist device (RVAD) were evaluated in a model of ischemic right ventricular (RV) failure. The right coronary artery (RCA) was ligated for 240 min in 12 mongrel dogs. Group 1 (n = 5) was supported medically (iv fluids, epinephrine); Group 2 (n = 7) had an RVAD instituted 30 mins after RCA ligation, but no inotropic support was given. The RVAD was a standard roller pump providing right atrial to pulmonary artery flow which unloaded the RV. The ratio of area of infarction (AI) to area at risk (AR) of the RV was determined by vital dye staining. Total lung water (TLW) was determined by gravimetric analysis and expressed as milliliters per kilogram body weight. Throughout the experiment animals in Group 1 had significantly higher RV systolic pressures. Pulmonary vascular resistance was increased significantly in Group 2 at 4 hr (318% of baseline vs 33%). Mean pulmonary artery pressure increased significantly in Group 2 from 9.4 +/- 0.9 mm Hg at baseline to 21.0 +/- 5.0 mm Hg at 4 hr. Group 2 animals had a decreased AI/AR ratio (19 +/- 3 vs 57 +/- 9) and increased TLW (20 +/- 3 vs 9 +/- 1). Lung biopsies in Group 2 revealed perivascular, peribronchial, and intraalveolar hemorrhages that were not present in Group 1. In conclusion, a roller pump RVAD limits RV infarction but produces pulmonary hypertension, increases pulmonary vascular resistance, and creates pulmonary edema and hemorrhage in the process.

Animals↗
PubMed1988

Enhancement of CO2 laser microvascular anastomoses by fibrin glue.

Laser-assisted microvascular anastomoses (LAMA) are characterized by low early bursting strength and high aneurysm rates. The effects of fibrin glue on bursting strength (BS), patency, and aneurysm rate of LAMAs were compared to standard suture and laser anastomosis. Rat femoral arteries (0.9-1.1 mm) were anastomosed end-to-end by three methods: (1) conventionally with 8 to 10 interrupted 10-O nylon sutures; (2) 3 stay sutures and CO2 laser (spot size, 0.275 mm; pulse, 0.2 sec, 80 mW); and (3) cryoprecipitated fibrinogen, 35 mg/cc, crystallized thrombin, CaCl, 20 mg/cc, aprotinin (2000 kIU/cc) applied to weld site in conjunction with laser weld as in (2) above. Patency, aneurysms, and histology were evaluated at 3 weeks, and BS (mm Hg) was measured in six additional vessels at 1 and 24 hr. There was no statistically significant difference in patency rates. Both the suture and fibrin glue groups had significantly higher 1 and 24 hr bursting strengths (P less than 0.05) and significantly lower aneurysm rates (P less than 0.001) than standard laser. There was no significant difference in bursting strength between suture and fibrin glue groups. Histology in the fibrin glue group showed medial damage similar to the LAMA and calcification of aneurysmal vessels. Fibrin glue enhancement of LAMAs produces equal patency, higher early bursting strength, and fewer aneurysms at 3 weeks compared to conventional laser.

Anastomosis, Surgical↗
PubMed1988

The surgical management of empyema thoracis in substance abuse patients: a 5-year experience.

Postpneumonic empyema (EMP) may develop in substance abuse patients, requiring prolonged hospitalization. An algorithm that provides quality care and a rational basis for timely surgical intervention would be advantageous. We report our five-year experience with EMP in substance abuse patients and present such a treatment plan. Sixty-one substance abuse patients were treated for EMP. Posteroanterior, lateral, and decubitus x-ray studies were obtained before treatment to assess fluid movement. Chest tubes were placed to drain frank pus and to obtain material for positive smears. X-ray studies and computed tomography were done 24 hours later to assess parenchymal pathology and to detect any multiple loculations. Thirty-three substance abuse patients recovered following initial tube thoracostomy and 7 after a second chest tube was introduced. Twenty-one had multiple loculations and underwent thoracotomy. Twenty of the 21 required extensive debridement or decortication, or both; 2 required lobectomy and 1 pneumonectomy. Chest tubes were removed on an average of 6 +/- 1.5 days. Average postoperative stay was 10.7 +/- 2 days. There were 2 early deaths and 1 late death and no recurrent EMP. Bacteriology findings were nonspecific and often polymicrobial. We conclude that early thoracotomy can be lifesaving in the presence of a benign clinical course.

Adolescent↗