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Biomedical subjects

J N Cunningham

Publications and source records attributed to J N Cunningham.

At least 109 records · Page 6Linked to original sources
PubMed1984

Patterns of severe pancreatic injury following cardiopulmonary bypass.

Severe pancreatic complications following cardiac surgery are rare, but 14 patients with severe pancreatitis have been encountered since 1971. Six of these developed acute fulminating pancreatitis following cardiac surgery and each of these died within 21 days following operation. Seven patients had less severe pancreatitis, resulting in pancreatic abscess formation and five in this group expired. One patient developed a pancreatic pseudocyst following mild acute pancreatitis and expired 4 months later. Although the etiologic mechanisms are unclear, possible factors include: prolonged cardiopulmonary bypass, "the low cardiac output syndrome," and inadequately treated or unrecognized postoperative pancreatitis. The diagnosis is based on physical examination, upper gastrointestinal series, and the abdominal CT scan. Despite aggressive surgical therapy, pancreatitis following cardiopulmonary bypass is an extremely serious condition.

Abscess↗
PubMed1984

Use of profound hypothermia and circulatory arrest for the calcified aorta.

This case report discusses one method of dealing with the extensively calcified aorta in patients undergoing open heart surgery. Profound hypothermia and circulatory arrest was used in a patient undergoing aortic valve replacement with severe calcification of the ascending aorta and transverse arch. This patient recovered from surgery and was discharged from the hospital with no neurologic deficits.

Aged↗
PubMed1984

Myocardial protection during prolonged aortic cross-clamping. Comparison of blood and crystalloid cardioplegia.

We compared the ability of blood and crystalloid cardioplegia to protect the myocardium during prolonged arrest. Twelve dogs underwent 180 minutes of continuous arrest. Group I (six dogs) received 750 ml of blood cardioplegic solution (potassium chloride 30 mEq/L) initially and every 30 minutes. Group II (six dogs) received an identical amount of crystalloid cardioplegic solution (potassium chloride 30 mEq, methylprednisolone 1 gm, and 50% dextrose in water 16 ml/L of electrolyte solution). Temperature was 10 degrees C and pH 8.0 in both groups. Studies of myocardial biochemistry, physiology, and ultrastructure were completed before arrest and 30 minutes after normothermic reperfusion. Biopsy specimens for determination of adenosine triphosphate were obtained before, during, and after the arrest interval. Regional myocardial blood flow, total coronary blood flow, and myocardial oxygen consumption were statistically unchanged in Group I (p greater than 0.05). Total coronary blood flow rose 196% +/- 49% in Group II (p less than 0.005), and left ventricular endocardial/epicardial flow ratio fell significantly in this group from 1.51 +/- 0.18 to 0.8 +/- 0.09, p less than 0.01 (mean +/- standard error of the mean. The rise in myocardial oxygen consumption was not significant in this group (34% +/- 36%, p greater than 0.05). Ventricular function and compliance were statistically unchanged in both groups. In Group II, adenosine triphosphate fell 18% +/- 3.4% (p less than 0.005) after 30 minutes of reperfusion; it was unchanged in Group I. Ultrastructural appearance in both groups correlated with these changes. We conclude that blood cardioplegia offers several distinct advantages over crystalloid cardioplegia during prolonged arrest.

Adenosine Triphosphate↗
PubMed1984

Paraplegia following percutaneous insertion of an intra-aortic balloon.

Paraplegia following insertion of an intra-aortic balloon is an extremely rare and unusual complication with only one previous report in the literature. We recently encountered this problem in a man with severe coronary disease and unstable angina. The etiology of this complication, although never established in our patient, was most likely a critical occlusion of a spinal cord artery as a result of either a small dissection or an arterial embolus.

Aged↗
PubMed1983

'Pulsatile' left atrial-femoral artery bypass. A new method of preventing extension of myocardial infarction.

A left atrial-femoral artery (LA-FA) bypass system was designed to deliver synchronous pulsatile blood flow. We compared it with nonpulsatile LA-FA bypass in its effectiveness to limit infarct extension after ligation of the left anterior descending coronary artery at its origin in 35 dogs. Nonpulsatile LA-FA bypass resulted in a 70% reduction in the size of infarct. The addition of synchronous diastolic counterpulsation (P-LA-FA) further reduced the size of infarct, when compared with that in controls (95%) or animals that underwent LA-FA bypass (83%). Both LA-FA and P-LA-FA bypasses limited infarct extension and reduced mortality after acute coronary occlusion through effective unloading of the left ventricle. The addition of diastolic counterpulsation to LA-FA bypass led to further significant infarct reduction, when compared with LA-FA bypass alone. These effects were most likely secondary to improvements in myocardial blood flow distribution.

Animals↗
PubMed1983

Experimental and clinical assessment of the adequacy of partial bypass in maintenance of spinal cord blood flow during operations on the thoracic aorta.

We studied both experimentally and clinically the efficacy of partial bypass techniques in maintaining spinal cord blood flow and physiological function during surgical procedures on the thoracoabdominal aorta. We attempted to define the level of distal aortic pressure required to safely ensure normal neurological function in the absence of critical intercostal occlusion. Six dogs underwent left thoracotomy with baseline measurements of spinal cord blood flow and spinal cord impulse conduction (somatosensory evoked potentials). Following exclusion of the entire descending thoracic aorta from the left subclavian artery to the T-13 level, partial left atrium-femoral artery bypass was instituted, and baseline levels of proximal and distal aortic pressure were maintained during a 30-minute stabilization period. Mean distal aortic pressure then was progressively altered at 30-minute intervals to 100, 70, and 40 mm Hg. Measurements of spinal cord blood flow and somatosensory evoked potential were repeated at the end of each interval for comparison with baseline. No significant changes in spinal cord blood flow or somatosensory evoked potential were observed in any animal with a distal aortic pressure greater than or equal to 70 mm Hg. With a pressure of 40 mm Hg, normal flow and somatosensory evoked potentials were maintained in 5 of the 6 dogs. Loss of somatosensory evoked potential, with simultaneous loss of spinal cord blood flow at the T-6 level, occurred in 1 dog. Restoration of distal aortic pressure to 70 mm Hg in all animals resulted in immediate return of somatosensory evoked potential. Loss of somatosensory evoked potential routinely occurred in animals with a distal aortic pressure less than 40 mm Hg. Clinically, 9 patients have undergone operation for lesions of the thoracoabdominal aorta using shunt or bypass techniques. Normal somatosensory evoked potentials were preserved in 7 patients with maintenance of adequate distal aortic pressure (greater than or equal to 60 mm Hg) without evidence of postoperative neurological deficit. Two patients showed hypotensive somatosensory evoked potential loss (distal aortic pressure less than 40 mm Hg). Prolonged distal hypotension (85 minutes of aortic cross-clamping) in the latter resulted in paraplegia. We conclude that maintenance of a distal aortic pressure greater than 60 to 70 mm Hg will uniformly preserve spinal cord blood flow in the absence of critical intercostal exclusion. Should distal aortic pressure be inadequate, early reversible changes in the somatosensory evoked potential will alert the surgeon. Failure to institute measures to reverse these changes may result in paraplegia.

Animals↗
PubMed1983

Definition of the safe lower limits of aortic resection during surgical procedures on the thoracoabdominal aorta: use of somatosensory evoked potentials.

The technique of intraoperative monitoring of somatosensory evoked potentials was applied to a canine model of spinal cord ischemia in an attempt to determine the safe lower limits of aortic resection during thoracic aortic surgery. Fifteen animals underwent left thoracotomy with institution of partial left atrial/femoral artery bypass for maintenance of distal aortic perfusion after proximal descending thoracic aortic exclusion. In Group I animals (n = 6, control), no further interventions were performed so that the effect of exclusion of vessels noncritical to spinal cord blood supply could be assessed by measurements of spinal cord blood flow and somatosensory evoked potentials. In Group II animals (n = 8), the level of distal aortic exclusion was progressively lowered until loss of somatosensory evoked potential (critical vessel exclusion) occurred. The effect of critical vessel exclusion on spinal cord blood flow was then assessed. Exclusion of multiple vessels noncritical to spinal cord blood supply (Group I) had no effect on spinal cord blood flow or function (somatosensory evoked potentials). Exclusion of vessels critical to spinal cord blood supply resulted in significant spinal cord ischemia (83.4% flow reduction, probability [p] less than 0.05 versus baseline) and ischemic spinal cord dysfunction (loss of somatosensory evoked potential).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1983

Preservation of myocardial ATP. Comparison of blood vs crystalloid cardioplegia.

Preservation of myocardial high-energy phosphates correlates with the heart's ability to resume normal function following aortic crossclamping (AXC). The ability of the canine myocardium to synthesize and maintain ATP during 180 minutes of AXC was evaluated in 12 hearts subjected to either blood or crystalloid cardioplegic arrest. Group 1 hearts were arrested by infusion of 750 ml of blood potassium cardioplegia (BKC) solution into the aortic root initially and every 30 minutes, as were group 2 (six) hearts but with a crystalloid cardioplegia (CC) solution. Transmural left ventricular biopsy specimens were obtained for ATP analysis prior to AXC (control), before and after cardioplegia injections 2, 4, and 6, prior to unclamping (180 minutes of AXC), and 30 minutes following reperfusion. ATP levels increased significantly above control (p less than 0.005) during the 180 minutes of AXC immediately following infusion of BKC. At the end of 180 minutes of AXC and following 30 minutes of reperfusion, ATP was noted to be normal in this group (p = NS). In contrast, ATP levels fell significantly (p less than 0.005) during the period of aortic cross-clamping in the crystalloid cardioplegia group and did not return to normal even after 30 minutes of reperfusion (p less than 0.005). We concluded that BKC, by presenting the arrested myocyte with adequate oxygen and substrate, allows for synthesis and preservation of myocardial ATP during periods of AXC as long as three hours. In this respect, it should be regarded as superior to CC, which permits a statistically significant depletion of ATP (p less than 0.005) uncorrected, even after 30 minutes of reperfusion in the beating, nonworking state.

Adenosine Triphosphate↗
PubMed1983

Late functional and hemodynamic status of surviving patients following insertion of the left heart assist device.

Since July, 1978, we have inserted a roller pump type of left heart assist device between the left atrium and ascending aorta in 35 patients. There were no significant complications related to use of the device. Seventeen patients recovered sufficiently to have the device removed. There were four early deaths, 60 to 120 days following removal of the device. Three of these patients died of septic complications and one patient died as a result of a cardiac arrest. Of the 13 long-term survivors, seven are working and six are retired. Five patients have mild to moderate cardiac symptoms, whereas eight others are completely asymptomatic. In three patients the ejection fraction was significantly lower than preoperatively; however, in all other patients the ejection fraction either stayed the same or improved postoperatively. We conclude that this type of left heart assist device can provide adequate cardiac support in patients with profound left ventricular dysfunction following cardiac operations. Furthermore, surviving patients generally have satisfactory long-term cardiac function and are leading productive lives.

Adult↗
PubMed1983

Left atrium-to-femoral artery bypass: effectiveness in reduction of acute experimental myocardial infarction.

The effects of prompt institution of left atrium-to-femoral artery (LA-FA) bypass on myocardial infarct area (AI) as a percentage of myocardial area at risk for infarction (AR) during a 4 hour period following ligation of the left anterior descending coronary artery (LAD) were studied in 26 dogs. Following LAD ligation, baseline measurements of myocardial tension-time index (TTI) and regional myocardial blood flow (RMBF) were obtained. Group I (controls, n = 16) received no further support. Group II (LA-FA bypass, n = 10) underwent left ventricular unloading via LA-FA bypass beginning 15 minutes after coronary occlusion. Four hours after LAD occlusion, measurements of TTI and RMBF were repeated in both groups. Just before sacrifice, gentian violet was injected into the aortic root to delineate the AR. The hearts were then removed and sectioned transversely through the left ventricle (LV) and septum. The AR (that ventricular area not perfused by gentian violet) was measured by planimetry and compared to the AI as identified by incubation of heart slices in triphenyltetrazolium chloride dye. In comparisons of control versus LA-FA bypass groups, both AI/LV (21.6% versus 10.4%) and AI/AR ratios (73.7% versus 21.8%) were significantly reduced in the bypass group (p less than 0.005). Mortality in the control group (5/16, 31.2%) was significantly greater (p less than 0.005) than in the bypass group (0/10, 0%). Mean TTI over the 4 hour ischemic period was essentially unchanged in the control group as compared to a reduction of 62.8% in the bypass group (p less than 0.005). Furthermore, RMBF at 4 hours was significantly improved in all regions of the LV in hearts undergoing LA-FA bypass when compared with control hearts (p = 0.025). These results demonstrate by a consistent method that prompt institution of LA-FA bypass significantly reduces the mortality associated with acute coronary artery occlusion, as well as the total AI and AI/AR. The protective mechanisms provided by LA-FA bypass probably include the highly significant reduction of LV work and the opening of new bridge collateral blood vessels with redistribution of blood flow to the ischemic region.

Animals↗
PubMed1982

Red blood cell sodium content and permeability changes in hemorrhagic shock.

Recent studies of cellular function have demonstrated significant alterations of cell homeostasis during hemorrhagic shock. The progressive depolarization of cell membranes demonstrated in several organs has been attributed to failure of energy-dependent active ion transport. Similar changes in intracellular electrolyte composition have been observed in the red blood cells of some patients in late hemorrhagic shock and in other severely ill patients. The ready availability of isolated cells that do not require extracellular fluid space assessment makes the red blood cell an attractive model for investigating the factors controlling ion movements across the cell wall. It has been suggested that the red blood cell ion abnormalities may represent a generalized cellular response to severe illness. Red blood cell sodium concentration was measured in 145 patients during severe hemorrhagic shock. The direction and magnitude of changes in red blood sodium concentration was correlated with the time course of the shock state. The initial decrease in sodium content was a function of the diminished red blood cell membrane permeability due to a decrease in plasma bicarbonate levels. The subsequent red blood cell sodium uptake above the normal range, not associated with an increase in sodium influx, indicated an impairment of energy-dependent active transport. The observed high sodium concentrations associated with a potassium decrease in the red blood cell appeared to be only one manifestation of a generalized defect in cellular function and composition during severe hemorrhagic shock.

Biological Transport, Active↗
PubMed1982

Myocardial protection with cold blood potassium cardioplegia during prolonged aortic cross-clamping.

The efficacy of cold blood potassium cardioplegia during periods of aortic cross-clamping (greater than 100 minutes) was assessed in 127 patients undergoing a variety of open-heart surgical procedures at New York University Medical Center from january, 1978, to April, 1979. Ischemic intervals ranged from 100 to 267 minutes (mean, 128 minutes). Cardiac-related deaths occurred in only 3 patients (2.4%), and overall operative mortality was 8.7% (11 patients). The rate of perioperative infarction was 10%. Fourteen patients (11%) required vasopressor support or balloon counterpulsation after cardiopulmonary bypass despite the lengthy cross-clamp intervals. Multivariate analysis revealed no significant relationship between the length of cross-clamp time and operative mortality (p = 0.29), incidence of perioperative infarction (p = 0.54), or the occurrence of low-output syndrome postoperatively (p = 0.68). These findings suggest that cold blood potassium cardioplegia provides adequate myocardial protection when periods of arrest as long as 3 to 4 hours are required for complex cardiac surgical procedures.

Adult↗
PubMed1982

Early open radical commissurotomy: surgical treatment of choice for mitral stenosis.

Between 1967 and 1979, 411 patients underwent surgical treatment of isolated mitral stenosis at our institution. Open radical mitral commissurotomy was performed in 150 patients (1967-1978; mean follow-up, 46 months; range, 4 to 116 months). Mitral valve replacement using a porcine prosthesis was performed in 74 patients (1976-1979; mean follow-up, 23 months; range, 2 to 48 months). Mitral valve replacement with a cloth-covered Starr-Edwards prosthesis was performed in 187 patients (1967-1975; mean follow-up, 45 months; range, 2 to 106 months). Preoperative characteristics were similar in the three groups. The open commissurotomy and Starr-Edwards groups were followed up to 9 years and the porcine valve group up to 4 years, with 97% follow-up in each group. Life-table analysis (6-month intervals) of all postoperative complications revealed significantly greater complication-free survival for patients who had open radical commissurotomy compared with Starr-Edwards (p less than 0.05) valve replacement. Similar analysis of thromboembolic and warfarin-related complications revealed significantly fewer complications in commissurotomy patients. No significant differences were found (p greater than 0.05) when comparing the need for subsequent reoperation in each group. Operative mortality following open radical mitral commissurotomy (0%; 0 out of 150) was significantly less (p less than 0.05) than after mitral valve replacement in both porcine (8.1%; 6 out of 74) and Starr-Edwards (11.2%; 21 out out 187) groups. Life-table analysis of late cardiac-related mortality revealed a significantly greater cumulative survival rate for the commissurotomy versus the Starr-Edwards groups at all intervals from 12 to 108 months (100 versus 84 +/- 5%, p less than 0.05). No significant differences were noted between commissurotomy and porcine valve groups during the 4-year follow-up period (100 +/- 0% versus 96 +/- 3%, p greater than 0.05). Based on these findings, we conclude that when the anatomy is favorable, the surgical treatment of choice for isolated mitral stenosis is open radical mitral commissurotomy.

Adolescent↗
PubMed1982

Measurement of spinal cord ischemia during operations upon the thoracic aorta: initial clinical experience.

Paraplegia has been an unpredictable, devasting complication following operations upon the thoracoabdominal aorta for over 30 years. The frequency ranges from 0.5% with operations for coarctation to as high as 15% following surgery for thoracoabdominal aneurysms. Both uncertainty and controversy exist about the value of different protective methods during aortic crossclamping (AXC): heparinized shunts, partial bypass, and reimplantation of intercostal arteries. This report describes the authors' initial clinical experience with a highly sensitive indicator of spinal cord ischemia, somatosensory evoked potentials (SEP) in an attempt to prevent paraplegia associated with surgical procedures on the thoracoabdominal aorta. Seven consecutive patients (one coarctation, five thoracic aneurysms, one thoracoabdominal aneurysm) underwent continuous operative monitoring of SEP. Cortical response to simultaneous electrical stimulation (20 mAmps, 0.6 mSec., 2.3 cps) of both the right and left posterior tibial nerves was recorded before, during, and after AXC, and following operation. When ischemic changes were detected by SEP, increasing distal circulation by different maneuvers (heparinized shunt, femoral-femoral bypass, reimplantation of intercostal arteries) reversed these changes. In two patients with thoracic aneurysms, ischemic changes appeared within three minutes after AXC and all potentials disappeared in nine minutes. Rapid insertion of a graft (AXC 28 and 37 minutes) resulted in SEP return 40 minutes following restoration of flow. These changes were prevented by a heparinized shunt in two patients, femoral/femoral bypass in one, and T8-T9 intercostal reimplantation in one. No SEP changes occurred in the patient with coarctation. No postoperative neurologic complications occurred. Continuous operative monitoring of SEP has exciting possibilities for preventing paraplegia. It is simple, highly sensitive, and seems to provide a precise measurement of adequacy of circulation to the spinal cord.

Adolescent↗
PubMed1982

The factors influencing early patency of coronary artery bypass vein grafts: correlation of angiographic and ultrastructural findings.

To test the hypothesis that suboptimal preparation of saphenous veins may adversely affect early patency of aorta-coronary artery bypass grafts, a nonrandomized prospective study was undertaken comparing two methods of saphenous vein preparation prior to grafting. Forty recatheterizations were performed during the postoperative hospital stay (approximately 10 days) in two groups of asymptomatic patients who had undergone isolated coronary artery bypass grafting. Veins from patients in Group I were bathed in autologous, heparinized blood at 20 degrees C and distended to 80 mm Hg, prior to grafting. The veins from Group II patients were prepared in an identical manner, except that the bathing solution consisted of heparinized electrolyte solution with added papaverine (0.6 mg/lg). Segments of vein from each group were obtained prior to grafting and preserved in 3% glutaraldehyde for subsequent electron microscopic studies. Operative technique in both groups of patients was identical and all procedures were performed by the same surgeons. Comparison of patients in Group I and II revealed no significant difference in the number of diseased vessels per patient (3.1 versus 3.4), number of grafts per patient (2.9 versus 2.9), native vessel diameter (1.9 versus 1.7 mm), and postoperative graft flows (65 versus 68 cc/min). However, early postoperative graft patency in Group II patients was 93% versus 80% in patients in Group I (p less thn 0.01). Electron microscopic analysis revealed severe spasm of venous smooth muscle in the blood-stored veins causing intraluminal smooth muscle cell cytoplasmic protrusions with resultant endothelial separation and desquamation. Formation of fibrin-platelet microaggregates was common. These findings were not present in the solution-treated veins. In view of these ultrastructural findings, and the highly significant difference in patency rates, we have abandoned all blood storage techniques and now prepare saphenous veins by soaking them in a clear bathing medium with added heparin and papaverine. Long-term follow-up of these patients is currently in progress and may reveal even more dramatic results than we have heretofore observed.

Coronary Angiography↗
PubMed1982

Long-term survival with partial left heart bypass following perioperative myocardial infarction and shock.

During the period from July 1, 1978 to Dec. 31, 1980, we employed a partial left heart bypass (left atrium to ascending aorta) in 16 patients who could not be weaned from cardiopulmonary bypass with inotropic agents and the intra-aortic balloon pump. Flow rates up to 3,500 ml/min could be obtained with this device. Eight of the 16 patients survived and left the hospital. One patient died of a cardiac arrest 4 months postoperatively and one has recurrent angina and moderate congestive heart failure 24 months postoperatively. Six patients are well 5 to 17 months after discharge. Seven of the eight deaths were characterized by progressive myocardial failure. One patient died of ventricular fibrillation 18 hours after discontinuation of the left heart bypass. All survivors had significant improvement in ventricular function 12 to 24 hours afer institution of the left heart bypass, which was continued for 16 to 68 hours. These results indicate that early institution of left heart bypass in seriously ill patients can provide satisfactory long-term results.

Aged↗