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Biomedical subjects

J N Cunningham

Publications and source records attributed to J N Cunningham.

At least 73 records · Page 4Linked to original sources
PubMed1988

The temporal relationship in arterial and venous prostacyclin and thromboxane activity during 24 hours of intraaortic balloon counterpulsation in dogs.

We studied the effects of intraaortic balloon counterpulsation (IABCP) on prostacyclin (PGI2) and thromboxane (TXB2) levels in dogs during 24 hours of 1:1 IABCP or a sham procedure in which the balloon was positioned but left deflated. The arterial PGI2 levels in the IABCP group increased from control values of 95 +/- 20 pg/ml to 268 +/- 95 pg/ml at 1 hour, 429 +/- 95 pg/ml at 4 hours, and 1,884 +/- 532 pg/ml at 24 hours. The arterial PGI2 levels were consistently higher in the IABCP group. Although the TXB2 measurements revealed no significant differences between groups, the IABCP group consistently had a higher level than the sham group. The platelet count in the control group decreased to 45% of baseline levels versus 55% for the IABCP group. We conclude that prolonged IABCP results in either net production of PGI2 or decreased degradation. The correlation between TXB2 and platelet counts is unclear and remains to be defined.

Animals↗
PubMed1988

Relationship of estrogen and progesterone receptors to prognosis in breast cancer.

To ascertain the role of estrogen (ER) and progesterone (PR) receptors as prognostic indicators of resectable breast cancer, the records of 204 patients were analyzed whose receptor studies were done at the Maimonides Medical Center from 1975 to 1983. All patients had radical or modified radical mastectomies and did not show any evidence of distant metastases at the time of operation. Median follow-up was 37 months. An additional 117 patients received some form of adjuvant therapy, mainly chemotherapy, and were analyzed separately. Life table analysis using the log rank test for measuring significance, and a Cox multivariate analysis was performed. At 48 months, 22% of the ER positive (ER+) group versus 33% of the ER negative (ER-) group had recurred as compared to 16% and 35% for the PR+ versus PR- groups, respectively. Life table analysis of the disease free interval (DFI) showed that the difference between the ER+ and ER- groups was not significant (p greater than 0.1), while the difference in DFI between the PR+ and PR- groups was significant (p less than 0.05). Multivariate analysis revealed that the most important factors in predicting the DFI were nodal status (p less than 0.001), tumor size (p less than 0.025), and progesterone receptor status (p less than 0.05). Estrogen receptor status was not found to be significant. In conclusion, PR- patients have a shorter DFI than PR+ patients and that PR status is a more valuable predictor of DFI than ER status.

Aged↗
PubMed1988

Coronary artery bypass in septuagenarians. Analysis of mortality and morbidity.

Elective coronary artery bypass surgery can be performed with an expected operative mortality of 1-3%. However, the effects of age on morbidity and mortality in patients undergoing this procedure remain controversial. To analyze morbidity and mortality in septuagenarians undergoing isolated coronary artery bypass surgery, we compared the results in 685 septuagenarians with those in 3,142 patients under the age of 70 years, all of whom underwent this procedure from January 1981 to December 1986. A larger percentage of elderly patients had triple-vessel disease (89% vs. 71%), left main coronary artery obstruction (34% vs. 16%), and ejection fractions less than 45% (68% vs. 41%). A larger percentage of septuagenarians had perioperative myocardial infarction (8% vs. 2%), required prolonged ventilatory support (10% vs. 3%), and had major neurological complications (4% vs. 1%). Mortality rates were significantly higher in elderly patients (7% vs. 2%) but did not correlate with the severity of coronary artery disease, the anginal pattern, or the diminishment of ventricular function. Major causes of mortality were pulmonary failure, renal failure, or both, sepsis, and neurological complications. These data suggest that elderly patients have an increased risk of cardiac and noncardiac morbidity and mortality after coronary artery bypass surgery. Higher mortality rates in this age group appear attributable to noncardiac organ failure. Late follow-up studies failed to show any significant difference among patients based on age alone.

Aged↗
PubMed1988

Transfusion-associated-graft-vs-host disease in a presumed immunocompetent patient.

Since the advent of bone marrow transplantation, a vexing clinical problem is that of acute graft-vs-host disease (GVHD). A less well-recognized disorder is that of GVHD in patients receiving blood products containing immunocompetent lymphocytes. Transfusion-associated (TA)-GVHD has a lower incidence and higher mortality (greater than 90%) than bone marrow transplantation-GVHD and until now has been limited to patients with hereditary or acquired immunologic deficits and to patients immunocompromised by chemotherapy for malignant neoplasms. We presently describe a patient who underwent coronary artery bypass graft surgery and who suffered what we believe was TA-GVHD. This diagnosis is supported by considering the chronology of events (in particular, blood transfusion), clinical features (fever, rash, abnormal results of liver function tests, diarrhea, and pancytopenia), and a skin biopsy specimen that revealed basal cell vacuolation and lymphocyte satellitosis that are considered characteristic for this disorder. We believe TA-GVHD can occur in previously immunocompetent patients who receive transfusions of blood products containing functioning lymphocytes and that this awareness will lead to the discovery of additional cases and a better understanding of this disorder.

Acute Disease↗
PubMed1988

In vitro bursting strength studies of laser-welded tissue and comparison with conventional anastomosis.

We compared the mechanical integrity of microvascular anastomoses created with a carbon dioxide (CO2) laser with conventional suture anastomoses. Seventy rat femoral artery segments (35 lased and 35 sutured) were harvested at 1, 24, and 72 hours, and 1, 3, 6, and 12 weeks postoperatively. These segments were subjected to increasingly higher in vitro intraluminal hydrostatic pressures (bursting pressure). Conventionally sutured anastomoses exhibited significantly increased ability (p less than 0.05) to withstand greater bursting pressures than the laser-welded tissue up to 3 weeks postoperatively. After the third postoperative week, the laser anastomoses demonstrated increased bursting pressures compared with the conventional anastomoses. At the end of the 12-week period both groups demonstrated an ability to withstand supraphysiologic pressures in excess of 2000 mm Hg.

Anastomosis, Surgical↗
PubMed1988

Stercoral perforation of the colon: report of a new location.

Stercoral perforations of the colon unassociated with obstructive lesions are rarely reported. With the exception of one case report which described a stercoral perforation of the cecum, all the reported perforations occurred at the sigmoid or rectosigmoid colon. This report describes a new location of perforation which hitherto has not been reported.

Aged↗
PubMed1988

Somatosensory evoked potentials and spinal cord perfusion pressure are significant predictors of postoperative neurologic dysfunction.

Paraplegia after thoracoabdominal aneurysm repair can occur in 3% to 40% of patients. This study investigated the efficacy of cerebrospinal fluid (CSF) drainage to protect the spinal cord during aortic cross-clamping (AXC) and the interrelationship between drainage, spinal cord perfusion pressure (SCPP), and changes in somatosensory evoked potentials (SEP) in a canine model of spinal cord ischemia. SCPP was defined as the mean distal aortic pressure minus the CSF pressure. In the experimental group, CSF was drained before AXC. SEP changes were quantitated as time to latency increase of 10% (L-10) and time to complete SEP loss. Drainage of CSF had no significant effect on the distal aortic pressure but significantly increased SCPP from 9.4 to 21.8 mm Hg and decreased the incidence of postoperative neurologic injury. Ischemic SEP changes were highly significant predictors of postoperative neurologic injury, occurring more than two times earlier in the paralyzed and paraparetic animals. Dogs without neurologic injury had significantly higher SCPP, delayed L-10 time, and delayed SEP loss.

Animals↗
PubMed1987

Thoracic surgery manpower: the fourth manpower study of thoracic surgery: 1985 report of the Ad Hoc Committee on Manpower of The American Association for Thoracic Surgery and The Society of Thoracic Surgeons.

Responding to a survey about their practice in 1985, 2,969 (70%) Board-certified thoracic surgeons provided data that were compared with data from manpower surveys in 1980 and 1976. (table; see text) Thoracic surgeons were most active between ages 35 and 54 years when they accomplished 61% of all general thoracic and 85% of cardiac operations. Surgeons older than 50 years performed significantly more general thoracic operations than younger surgeons, and the younger group performed significantly more cardiac operations than their older counterparts. Solo practice continued to decline. In smaller referral areas, the number of general thoracic procedures per surgeon increased, but the number of cardiac operations have decreased compared with 1980. Overall, general thoracic and cardiac operations increased, but peripheral vascular procedures and pacemaker insertions decreased in almost all nine census regions. Fewer general thoracic and cardiac operations were performed per thoracic surgeon in the western United States than in central and eastern regions. In response to questions about work load, 55% believed that their clinical activity was satisfactory, 42% operated too little, and 3% operated too much. The 363 non-Thoracic Board-certified surgeons who responded performed 14% of general thoracic and 8% of cardiac surgery in 1985. During the first half of the 1980s, our specialty certified an average of 134 thoracic surgeons annually, which is higher than the 120 surgeons per year estimated to meet the projected demand.

Adult↗
PubMed1987

Aortoesophageal fistula: case report and literature review.

Fistulous communication between the aorta and esophagus is a rare but usually fatal disorder. Esophageal foreign bodies have been reported to cause aortoesophageal fistula rarely. Spontaneous aortoesophageal fistula as a result of atherosclerotic disease of the aorta has not been reported. This article describes a case of aortoesophageal fistula caused by an ulcerated atherosclerotic plaque, which we believe is the first case report implicating such an etiologic factor.

Aged↗
PubMed1987

Reperfusion ventricular fibrillation during coronary artery bypass operations and its association with postoperative enzyme release.

Elevated creatine kinase MB level is the most common marker of myocardial infarction in patients who have had a recent coronary bypass operation. This study was performed to determine whether there is any relationship between reperfusion rhythms, their treatment, and postoperative creatine kinase MB concentrations. Twenty patients were monitored during coronary bypass operations. Four patients had no reperfusion ventricular fibrillation and no elevation of creatine kinase MB postoperatively. Of the 16 remaining patients, all had ventricular fibrillation and 12 had an elevation of postoperative creatine kinase MB (p less than 0.015). There was also a 75% correlation between the time in ventricular fibrillation and postoperative creatine kinase MB level. There was no correlation between other measured parameters, such as cross-clamp time, bypass time, or the number of defibrillations. It is concluded that reperfusion ventricular fibrillation is associated with release of creatine kinase MB, and the time in ventricular fibrillation is correlated with the postoperative creatine kinase MB level.

Aged↗
PubMed1987

Anesthetic and supportive management during experimental pulsatile flow perfusion studies in calves.

The purpose of this study was to determine the factors influencing successful experimental cardiopulmonary bypass studies using pulsatile flow perfusion and the medications and methodology necessary to produce successful bypass in calves. In six calves showing no cardiopulmonary pathology prior to bypass procedures, successful anesthesia and surgical intervention was accomplished. Animals were maintained on 5 hours of pulsatile flow bypass perfusion. Successful recovery from the procedures was accomplished. In two calves with pre-existing pulmonary pathology, anesthetic and surgical intervention was accomplished with the utilization of extensive anesthetic management and cardiac supportive medications until the animals could be initiated into 5 hours of pulsatile flow bypass perfusion, in spite of major pulmonary dysfunction. In these two animals, attempts to resuscitate upon termination of pulsatile flow perfusion were unsuccessful due to pre-existing excessive lesions in the lungs. This study shows a contrast between complete success of a pulsatile flow system in normal subjects versus the ultimate failure in experimental animals with pre-existing pulmonary pathology. The inability of experimental calves with a diseased lung to resume spontaneous cardiopulmonary function after the challenges of thoracic intervention indicates the unsuitability of animals with marked pre-existing pulmonary disease status for use in cardiopulmonary bypass studies.

Anesthesia, General↗
PubMed1987

Monitoring of somatosensory evoked potentials during surgical procedures on the thoracoabdominal aorta. I. Relationship of aortic cross-clamp duration, changes in somatosensory evoked potentials, and incidence of neurologic dysfunction.

To determine if intraoperative monitoring of somatosensory evoked potentials detects spinal cord ischemia, we subjected 21 dogs to aortic cross-clamping distal to the left subclavian artery. Group I animals (short-term studies, n = 6) demonstrated decay and loss of somatosensory evoked potentials at 8.5 +/- 1.1 minutes after aortic cross-clamping. During loss of somatosensory evoked potentials, significant decreases in spinal cord blood flow occurred in cord segments below T6. Significant reactive hyperemia occurred without normalization of somatosensory evoked potentials after reperfusion. Fifteen Group II animals (long-term studies) were studied to determine the relationship between duration of spinal cord ischemia (evoked potential loss) and subsequent incidence of paraplegia. Extension of aortic cross-clamping for 5 minutes after loss of somatosensory evoked potentials in six dogs resulted in no paraplegia (mean cross-clamp time 12.7 +/- 0.6 minutes). Prolongation of aortic cross-clamping for 10 minutes after evoked potential loss in nine dogs (mean cross-clamp time 17.6 +/- 0.6 minutes) resulted in a 67% (6/9) incidence of paraplegia 7 days postoperatively (p = 0.02 versus 10 minutes of aortic cross-clamping). These findings demonstrate that simple aortic cross-clamping uniformly results in spinal cord ischemia and that such ischemia is detectable by monitoring of somatosensory evoked potentials. Duration of ischemia, as measured by the time of evoked potential loss during the cross-clamp interval, is related to the incidence of postoperative neurologic injury.

Animals↗
PubMed1987

Monitoring of somatosensory evoked potentials during surgical procedures on the thoracoabdominal aorta. II. Use of somatosensory evoked potentials to assess adequacy of distal aortic bypass and perfusion after thoracic aortic cross-clamping.

Pulsatile left atrial-femoral artery bypass was instituted after aortic cross-clamping distal to the left subclavian artery in a canine experimental model to determine the relationship of distal aortic perfusion pressure with spinal cord blood flow and somatosensory evoked potentials. In six animals (Group I) distal aortic perfusion pressure was maintained at 100 mm Hg throughout a 1 hour interval of aortic cross-clamping. During this period, somatosensory evoked potentials and spinal cord blood flow (radioactive microspheres) showed no significant change from baseline. In six other dogs (Group II) distal aortic perfusion pressure was initially maintained at 100 mm Hg after aortic cross-clamping and then progressively decreased to 70, 40, and 25 mm Hg. Somatosensory evoked potentials and spinal cord blood flow were preserved at baseline levels for all distal perfusion pressures greater than 70 mm Hg. At 40 mm Hg, abnormalities in amplitude of the somatosensory evoked potentials were noted in all animals with progression to complete loss of evoked potential activity at lower perfusion pressures. Maintenance of adequate somatosensory spinal cord conduction after thoracic aortic cross-clamping is dependent on a critical level of distal aortic perfusion that can be accomplished by use of an adjunct such as pulsatile left atrial-femoral artery bypass. The critical level of distal aortic perfusion pressure to maintain normal somatosensory evoked potentials and spinal cord blood flow in this canine experimental study was 70 mm Hg or greater. Because inadequate distal aortic perfusion can be easily detected by monitoring of somatosensory evoked potentials, these techniques should prove helpful in evaluating the effectiveness of distal perfusion techniques during clinical aortic cross-clamping for procedures on the thoracoabdominal aorta.

Animals↗
PubMed1987

Monitoring of somatosensory evoked potentials during surgical procedures on the thoracoabdominal aorta. III. Intraoperative identification of vessels critical to spinal cord blood supply.

Somatosensory evoked potentials were used to locate intercostal arteries critical to spinal cord blood flow in nine dogs. To mimic a clinical situation, the proximal descending thoracic aorta (left subclavian artery to T7) was excluded with cross-clamps, and partial pulsatile left atrial-femoral artery bypass was instituted to maintain distal aortic pressure at 100 mm Hg. Progressively lower aortic segments were excluded (T7-10, T10-L1, L1-3, L3-6, L6-7) until loss of somatosensory evolved potentials occurred. Spinal cord blood flow measurements at the time of evoked potential loss revealed significant ischemia (p less than 0.02 versus baseline) in the excluded segment in seven animals but normal spinal cord blood flow in the remainder of the cord. Upon reperfusion, significant reactive hyperemia (p less than 0.02) was noted only in previously ischemic cord segments. Two animals exhibited no change in somatosensory evoked potentials or spinal cord blood flow despite exclusion of the entire thoracoabdominal aorta, presumably as a result of spinal collaterals. Loss of somatosensory evoked potentials despite adequate distal perfusion indicates that critical intercostal vessels have been excluded from systemic and bypass circulations. Use of evoked potential measurements in both experimental and clinical situations provides a means for assessing adequacy of spinal cord blood flow during cross-clamping and can alert the surgeon to the need for reimplantation of critical intercostal arteries during surgical resection of the thoracoabdominal aorta.

Animals↗
PubMed1987

Monitoring of somatosensory evoked potentials during surgical procedures on the thoracoabdominal aorta. IV. Clinical observations and results.

Thirty-three patients undergoing operations on the descending thoracic or thoracoabdominal aorta were monitored to evaluate causes and effects of spinal cord ischemia as manifested by changes in somatosensory evoked potentials. Maintenance of distal aortic perfusion pressure (greater than 60 mm Hg) by either shunt or bypass techniques in 17 patients resulted in preservation of somatosensory evoked potentials and a normal postoperative neurologic status, irrespective of the interval of thoracic cross-clamping (range 23 to 105 minutes). In 16 other patients in whom cross-clamp time ranged from 16 to 124 minutes, evoked potential loss was observed because of failure to provide distal perfusion (n = 8), inadequate maintenance of distal perfusion pressure (less than 60 mm Hg) despite shunt/bypass (n = 6), or interruption of critical intercostal arteries (n = 2). Incidence of paraplegia in the entire group was 15.1% (5/33) and was limited to only those patients in whom evoked potential loss occurred (5/16, 31.2%) (p = 0.02). Loss of somatosensory evoked potentials for more than 30 minutes resulted in a 71.2% (5/7) incidence of paraplegia, whereas no neurologic deficit was noted in patients (0/26) in whom evoked potential loss was either prevented or limited in duration to 30 minutes (p less than 0.001 versus loss for more than 30 minutes). Intraoperative monitoring of somatosensory evoked potentials is a sensitive indicator of spinal cord ischemia. Simple aortic cross-clamping, failure to maintain distal perfusion pressure above 60 mm Hg, and inability to reimplant critical intercostals in a timely fashion result in a high rate of paraplegia if duration of spinal cord ischemia as measured by somatosensory evoked potentials exceeds 30 minutes. Routine evoked potential monitoring during thoracoabdominal procedures appears useful in assessing the adequacy of spinal cord perfusion. Furthermore, it can alert the surgeon to the necessity for critical intercostal artery reimplantation as well as the need for adjustment or regulation of distal aortic perfusion.

Adolescent↗
PubMed1987

Results of open heart surgery in patients with recent cardiogenic embolic stroke and central nervous system dysfunction.

Patients undergoing open heart surgery who have had recent cardiogenic embolic stroke or have central nervous system dysfunction pose a difficult management problem. There is always the risk that cardiopulmonary bypass and heparinization may exacerbate the neurologic injury. There is no clear data indicating what is a safe interval of time from the onset of neurologic symptoms to the time of surgery. Since 1982 we have operated on 15 patients with recent (2 to 28 days, mean 12.7 +/- 7.9 days) neurologic injury. Indications for surgery included recurrent embolization, sepsis, and hemodynamic deterioration. Three patients were comatose with no focal neurologic signs at the time of surgery, and 12 patients had focal neurologic deficits. All patients had preoperative computed tomographic scans. Embolic cerebral infarctions were documented in 12 patients, one patient had evidence of intracranial hemorrhage, and one patient had a subdural hematoma. Fourteen patients had native or prosthetic valvular endocarditis and one patient had a left atrial myxoma. All patients underwent corrective cardiac surgery. One patient died in the postoperative period from multisystem failure; all other patients have been followed since discharge (6 months to 4 years). All surviving patients demonstrated improvement in their neurologic symptoms and eight patients had complete neurologic recovery. The results of this study indicate that open heart surgery can be safely performed in patients with recent neurologic injury.

Adolescent↗
PubMed1986

Etiology and clinical significance of new fascicular conduction defects following coronary bypass surgery.

Two hundred consecutive patients undergoing only coronary bypass surgery were studied. Forty-five patients (group A) developed new fascicular conduction blocks and 155 patients (group B) did not. The 45 patients in group A developed the following fascicular conduction blocks: right bundle branch block 47%, right bundle branch block and left anterior hemiblock 8%, right bundle branch block and first-degree atrioventricular block 2%, left anterior hemiblock 11%, left bundle branch block 18%, right bundle branch block-left anterior hemiblock and first-degree atrioventricular block 5%. There were no significant differences in sex, incidence of diabetes, number of grafts performed, ejection fraction (less than 55%), and perioperative infarction. Group A patients were older (p less than 0.01). Hypertension was found frequently in group A (27 vs 45 patients; p less than 0.01) and was present for a mean of 12.4 years in group A and 4.9 years in group B (p less than 0.01). Preoperative use of digitalis was found in 14 (31%) patients in group A and in 18 (12%) patients in group B (p less than 0.01). Twenty-one (47%) patients in group A had significant disease (greater than 70%) of the left main coronary artery as compared to 17 (10.9%) in group B (p less than 0.001). There was no difference in the recurrence of angina or the survival rate at 14 months. In conclusion, the incidence of new fascicular conduction block after bypass surgery is 22.5%. Long-standing hypertension, left main coronary disease, and the preoperative use of digitalis appear to be predisposing factors. New fascicular conduction block does not affect prognosis.

Age Factors↗