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Biomedical subjects

I L Kron

Publications and source records attributed to I L Kron.

At least 163 records · Page 9Linked to original sources
PubMed1989

Probing of the canine mammary artery damages endothelium and impairs vasodilation resulting from prostacyclin and endothelium-derived relaxing factor.

It is routine practice for many cardiac surgeons to probe internal mammary arteries to dilate them before their use. The effects of such probing on endothelium integrity, prostacyclin production, and vasodilation resulting from endothelium-derived relaxing factor and from prostacyclin were investigated in vessels isolated from mongrel dogs. Dose-dependent relaxation responses of isolated segments of probed and unprobed mammary arteries to the endothelium-dependent vasodilators methacholine, calcium ionophore (A23187), and melittin were determined in both the presence and absence of indomethacin. Prostacyclin production by probed versus unprobed vascular segments was determined under basal and A23187-stimulated conditions by radioimmunoassay for 6-keto-prostaglandin F1 alpha, and endothelial integrity was determined by scanning electron microscopy. Scanning electron micrographs of segments revealed marked endothelial cell disruption in probed versus unprobed vessels. The dose-dependent relaxation responses to all drugs studied were significantly impaired (p less than 0.05) in probed versus unprobed vessels in both the presence and absence of indomethacin. In addition, prostacyclin release as measured by production of 6-keto-prostaglandin F1 alpha was significantly (p less than 0.05) impaired in probed versus unprobed vessels under both basal and A23187-stimulated conditions. These results imply that routine probing of the internal mammary artery may damage endothelium, impair prostacyclin production, and impair endothelium-dependent vasodilation resulting from both prostacyclin and endothelium-derived relaxing factor.

Animals↗
PubMed1989

Airway obstruction after autologous reimplantation of the porcine lobe.

Bronchiolitis obliterans (irreversible small airway obstruction) is a late complication of heart-lung transplantation. Chronic immune rejection is believed to be the major cause of this complication. Our hypothesis was that denervation might contribute to airway obstruction. To test this hypothesis in the absence of immune rejection, we performed a lobectomy of the upper lobe of the left lung and autologous reimplantation of the lower lobe of the left lung in 13 growing pigs. To serve as age-matched controls, six other pigs had sham left thoracotomy and nine others had a lobectomy of the upper lobe of the left lung alone. Nine to 10 weeks after operation, the animals were anesthetized and the lungs mechanically ventilated. The lobes were then isolated in vivo to measure differential transrespiratory mechanics and volumes. Dynamic compliance was significantly lower in the reimplanted lobe than it was in the contralateral right lung. This was the case after lobectomy of the upper lobe of the left lung or sham thoracotomy. Dynamic resistance was significantly higher in the reimplanted lobe than it was in the contralateral right lung and in the left lung after sham thoracotomy. Measurements of extravascular lung water, dry lobe weight, alveolar cross-sectional area, and volumetric proportions of lung parenchyma and alveolar spaces did not demonstrate abnormal structural growth after reimplantation. We conclude that lobectomy of the upper lobe of the left lung and autologous reimplantation of the left lower lobe leads to adverse changes in flow-dependent measurements of airway patency. Changes in bronchomotor regulation imposed by denervation may contribute to airway obstruction after heart-lung transplantation.

Airway Obstruction↗
PubMed1989

Assessing clamp-related vascular injuries by measurement of associated vascular dysfunction.

The development of vascular clamps requires a reliable method to quantitate clamp-related vascular injuries. The degree of vessel damage usually is estimated subjectively from photomicrographs made with scanning electron microscopy. In order to test whether the use of vascular rings to assess residual vascular function may be a better method, rabbit thoracic aortas were occluded by five types of clamps: a Fogarty softjaw bulldog, a Fogarty Hydragrip, a 6-inch Satinsky clamp, an Edslab bulldog, and a silicone vessel band. Each area of clamp injury was sectioned into a vascular ring and suspended in a tissue bath. Residual vascular function was determined by contraction in response to phenylephrine and by relaxation in response to methacholine chloride and sodium nitroprusside. Morphologic studies with use of Evans blue dye and scanning electron microscopy complemented the vascular-function studies. The Fogarty bulldog clamp was the best at preserving vascular contraction and relaxation; the more crushing Satinsky clamp was the worst. The testing of vascular rings for residual function appears to be a useful technique for objectively quantitating vascular clamp-related vascular damage.

Animals↗
PubMed1988

Vena caval involvement with renal tumors: surgical considerations.

We reviewed the experience at the University of Virginia over the past 10 years with renal tumors involving the inferior vena cava. There were 107 patients with renal tumors, 41 with invasion of the renal vein and 18 with involvement of the inferior vena cava. The groups with and without vena caval tumors were compared, and the operative approach is described. Although the rate of complications was higher in operations on the vena cava, none were fatal and no patient required chronic dialysis. Life-table analysis revealed that patients with involvement of the inferior vena cava survived longer than those with incomplete resection. Because extraction of these tumors can be accomplished with acceptable morbidity and mortality, because complete resection confers a survival advantage, and because chemotherapy and radiation are ineffective, we recommend aggressive workup and resection of renal tumors involving the inferior vena cava.

Adult↗
PubMed1988

The effect of hyperemia on spinal cord function after temporary thoracic aortic occlusion.

Nineteen mongrel dogs had 30 minutes of thoracic aortic occlusion to determine the effects that blockade of the renin-angiotensin system may have on preserving spinal cord blood flow and function during a period of temporary spinal cord ischemia. Cross-clamping of the thoracic aorta causes renal ischemia and activates the renin-angiotensin system with resulting increased production of angiotensin II. Angiotensin II is a potent peripheral constrictor and elevated levels may constrict collateral spinal cord circulation. At the time of aortic cross-clamping, 10 dogs received 100 mg/kg of MK422 (intravenous enalapril maleate), a converting enzyme inhibitor, and nine animals served as controls. The blockade of the renin-angiotensin system had no preserving effects on spinal cord flow as measured by microspheres and on spinal cord function as graded with the Tarlov scale. However, the paraplegic animals all had significantly increased lower thoracic and lumbar spinal cord flows 30 minutes after clamp release when compared with those animals that remained neurologically intact. In conclusion, marked hyperemia occurring after a period of hypoperfusion may lead to spinal cord edema and compartment syndrome with resulting paraplegia.

Animals↗
PubMed1988

Reconstruction of full thickness chest wall defects.

Over the last 5 years, 14 patients were treated by wide en bloc resection of chest wall tumors with primary reconstruction. There were nine females and five male patients with an age range of 31-77 years. All patients had a skeletal resection of the chest wall. An average of 3.9 ribs were resected in the patients treated. In three patients a partial sternectomy was carried out in conjunction with the rib resections. Chest wall skeletal defects were reconstructed with Prolene mesh, which was placed under tension. Soft tissue reconstruction utilized selected portions of the latissimus dorsi musculocutaneous territory with fasciocutaneous extensions beyond the muscle itself. Primary healing was obtained in all patients and secondary procedures were not required. The average hospitalization was 23 days. All patients survived the resection and reconstruction and were alive 30 days after operation. In selected patients the preservation of a portion of the innervated muscle in situ or the transfer of the muscle with the preservation of its resting length has maintained the majority of the muscle function.

Adult↗
PubMed1988

Surgical ablation of ventricular tachycardia with sequential map-guided subendocardial resection: electrophysiologic assessment and long-term follow-up.

A new operative technique of sequential map-guided subendocardial resection (SER) was used in 45 consecutive patients for the treatment of sustained ventricular tachycardia due to coronary artery disease. This technique is characterized by map-guided SER or cryothermic ablation during normothermic cardiopulmonary bypass, followed by repeated sequences of programmed stimulation to assess adequacy of resection. The patients' mean age was 59 +/- 10 years and the mean left ventricular ejection fraction was 34 +/- 12%. Twenty-five (56%) patients had a history of myocardial infarction within the previous 2 months. After ventriculotomy, 34 patients (76%) had inducible monomorphic ventricular tachycardia. These patients underwent repeated sequences of ventricular tachycardia induction and mapping during normothermic bypass followed by successive SER or cryothermic ablation until sustained monomorphic ventricular tachycardia was no longer inducible. Twenty-seven patients had a total of 60 discrete, mappable tachycardias induced and seven patients had 10 discrete tachycardias that were too fast to accurately map. In the remaining 11 patients, no ventricular tachycardia was inducible after ventriculotomy and SER, which included all visually identifiable scar, was performed. The mean cardiopulmonary bypass time was 102 +/- 27 min. Forty-one of 45 patients (91%) survived to hospital discharge, and 35 of 41 patients (85%) had no inducible ventricular tachycardia at postoperative electrophysiologic evaluation performed in the absence of all antiarrhythmic drugs. The remaining six patients had no inducible ventricular tachycardia with drug therapy. All four operative nonsurvivors had refractory cardiac collapse preoperatively. Over 19 +/- 12 months of follow-up, there were four sudden cardiac deaths and no nonfatal recurrences of ventricular tachycardia. There were seven additional cardiac deaths. Actuarial cardiac survival was 0.57, and freedom from arrhythmic events was 0.76 at 42 months. Thus, in the absence of cardiogenic shock, the technique of sequential map-guided SER achieves: (1) a high operative survival with acceptable perfusion times, (2) excellent long-term arrhythmia control, and (3) survival comparable to that in patients with similar left ventricular function and no history of ventricular tachyarrhythmia.

Aged↗
PubMed1987

Symptomatic double aortic arch causing tracheal and esophageal compression in the adult.

A 50-year-old woman with a symptomatic double aortic arch that was successfully treated surgically is presented. Review of this abnormality notes that this anomaly rarely causes symptoms in adults. Greater awareness of the possibility of this condition as a cause of tracheal compression and dysphagia may lead to symptomatic relief for these patients.

Aorta, Thoracic↗
PubMed1987

Anterolateral thoracotomy as an alternative to repeat median sternotomy for replacement of the mitral valve.

Median sternotomy is the most common approach for repeat cardiac surgery despite the potential complications of cardiac injury. Right anterolateral thoracotomy has been recommended as an alternative for patients undergoing mitral valve replacement, but data supporting one approach over the other do not exist. To compare these procedures, the records of 43 patients who had had a previous median sternotomy and who underwent mitral valve replacement were reviewed. No statistically significant differences between patients undergoing repeat median sternotomy (33 patients) and those undergoing right anterolateral thoracotomy (10 patients) were demonstrable when compared for age, gender, New York Heart Association Functional Class, other diseased valves, urgency of operation, indication for operation, type of valve removed, type of valve implanted, length of postoperative hospitalization, length of operation, days of ventilatory support, length of intensive care unit stay, and survival (90% for thoracotomy group; 76% for median sternotomy group; p, NS). Significant differences between the two groups, favoring right anterolateral thoracotomy, were apparent when comparisons were made for length of perfusion (means, 94.8 min, thoracotomy group; 121.4 min, sternotomy group; p = .03), incidence of reexploration (0%, thoracotomy group; 13%, sternotomy group; p = .001), and blood transfusion (means, 5.3 units, thoracotomy group; 11.4 units, sternotomy group; p = .003). Right anterolateral thoracotomy is an effective alternative to repeat median sternotomy for replacement of the mitral valve in patients who have had a previous median sternotomy.

Heart Valve Prosthesis↗
PubMed1987

Repair of thoracic aortic aneurysms in the elderly: are shunts necessary?

Thoracic aortic aneurysms in elderly patients are being recognized with increasing frequency. A review of 12 patients 70 years of age or older who underwent repair of aneurysms of the descending thoracic aorta without the use of shunts or bypass revealed that this operation could be performed with acceptable morbidity and mortality. The two deaths in this series were patients who were operated on emergently, whereas all patients operated on electively or urgently survived to leave the hospital.

Aged↗
PubMed1987

Vascular trauma of the extremities: factors causing failure of arterial repair.

Vascular trauma of the extremities is a significant problem in our society as a result of vehicle accidents and violence. Excellent results of vascular repair can be expected with strict attention to bypass of all damaged vessel, proximal and distal embolectomy, regional heparinization, liberal fasciotomy, fixation of associated fractures, and soft tissue coverage of the repaired vessel.

Adolescent↗
PubMed1987

Esophageal anastomotic leaks: preliminary results of treatment with balloon dilation.

Disruption of a cervical esophagogastric or esophagocolonic anastomosis shortly after surgery is a common complication, and fistula drainage from the leaking anastomosis may be prolonged. Narrowing of the anastomosis apparently contributes to the development and maintenance of the fistula. Fluoroscopically guided balloon dilation of anastomotic strictures was performed in three patients with anastomotic leaks. Preliminary results suggest that the procedure is safe and promotes healing of the fistula.

Adult↗