Thoracoscopic implantation of the implantable cardioverter defibrillator.
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Adult↗
Biomedical subjects
I L Kron
Publications and source records attributed to I L Kron.
Balloon angioplasty above the aortic arch: immediate and long-term results.
OBJECTIVE: Angioplasty above the level of the aortic arch is becoming more common, and the indications for it are increasing. We report our experience with this procedure, including life-table analysis of the long-term results. MATERIALS AND METHODS: We dilated 32 lesions in 29 patients. Early in our series, patients were referred primarily because of arm claudication or vertebrobasilar insufficiency. Subsequently, the indications were expanded to include inflow to left internal mammary-coronary artery bypass grafts, inflow to axillobifemoral bypass grafts, and inflow to dialysis fistulas in the upper extremity. A femoral artery approach was used in 18 patients and an axillary approach was used in 11. Clinical follow-up included evaluation of symptoms and bilateral measurements of peripheral pulses and blood pressure. Follow-up angiograms were obtained in nine patients. RESULTS: Eighteen of the lesions dilated were located in the left subclavian artery, eight were in the right subclavian artery, four were in the axillary or proximal brachial artery, and two were in the innominate artery. Interestingly, three of eight right subclavian arteries treated had an anomalous origin from the arch of the aorta. Initial technical success was 100%. All 29 patients had long-term follow-up of 4-88 months (mean, 36 months). In one patient, stenosis recurred 8 months after angioplasty. This patient subsequently had redilatation. Life-table analysis projected a 7.5-year cumulative primary patency rate of 96.6%. No cerebrovascular complications or embolic events occurred. CONCLUSION: Angioplasty of the great vessels is safe and effective, and the long-term results are favorable when compared with results after surgery. As a result, the indications for this procedure should be broadened.
Adult↗
Limiting ischemic spinal cord injury using a free radical scavenger 21-aminosteroid and/or cerebrospinal fluid drainage.
Traumatic spinal cord injury occurs in two phases: biomechanical injury, followed by ischemia and reperfusion injury. Biomechanical injury to the spinal cord, preceded or followed by various pharmaceutical manipulations or interventions, has been studied, but the ischemia/reperfusion aspect of spinal cord injury isolated from the biomechanical injury has not been previously evaluated. In the current study, ischemia to the lumbar spinal cord was induced in albino rabbits via infrarenal aortic occlusion, and two interventions were analyzed: the use of U74006F (Tirilazad mesylate), a 21-aminosteroid, and cerebrospinal fluid (CSF) drainage. These treatment modalities were tested alone or in combination. In Phase 1 of this study, the rabbits received 1.0 mg/kg of Tirilazad or an equal volume of vehicle (controls) prior to the actual occlusion, three doses of Tirilazad (1 mg/kg each) during the occlusion, then several doses after the occlusion. Of the Tirilazad-treated animals, 30% became paraplegic while 70% of the control animals became paraplegic. Phase 2 involved the same doses of Tirilazad as in Phase 1 and, in addition, CSF pressure monitoring and drainage were performed. The paraplegia rate was 79% in the control animals, 36% in the group receiving Tirilazad alone, 25% in the group with CSF drainage alone, and 20% in the Tirilazad plus CSF drainage group. This rate also correlated with changes noted in CSF pressure; both Tirilazad administration alone and CSF drainage alone induced a decrease in CSF pressure and the two combined produced a further decrease. There was marked improvement in the perfusion pressure when using Tirilazad alone, CSF drainage alone, and Tirilazad therapy in combination with CSF drainage, with the last group producing the largest increase. This change in CSF pressure and perfusion pressure correlated with improved functional neurological outcome. Pathological examination revealed that Tirilazad therapy reduced the extensive and diffuse neuronal, glial, and endothelial damage to (in its most severe form) a more patchy focal region of damage in the gray matter. Cerebrospinal fluid drainage resulted in pyknosis of some motor neurons, and some eosinophilia. The combination of CSF drainage and Tirilazad administration resulted in the least abnormality, with either normal or near-normal spinal cords. It is concluded that Tirilazad administration decreased CSF pressure during spinal cord ischemia and reperfusion and, like CSF drainage, increased and improved the perfusion pressure to the spinal cord, decreased spinal cord damage, and improved functional outcome.(ABSTRACT TRUNCATED AT 400 WORDS)
Animals↗
Regional adenosine attenuates postischemic spinal cord injury.
PURPOSE: Operations on the thoracic and thoracoabdominal aorta are associated with postoperative paraplegia rates as high as 20% to 30%. Attempts to reduce this complication have focused on decreasing the energy needs of the spinal cord with protective agents such as hypothermia and barbiturates or on increasing blood flow with various shunts. This study explores the hypothesis that perfusion of the spinal cord with hypothermic solutions or with adenosine will prevent or ameliorate paraplegia. METHODS: New Zealand white rabbits underwent 40 minutes of infrarenal aortic isolation. The infrarenal aorta is the primary source of spinal cord blood supply in the New Zealand white rabbit. Control rabbits sustained aortic occlusion without any protective measures. The remaining animals were randomized into three groups that underwent aortic cross-clamping with various protective adjuncts. Group I received regional aortic hypothermia perfusion, group II received systemic adenosine, and group III received regional aortic perfusion with high-dose adenosine. RESULTS: Neurologic function was graded according to the Tarlov scale (0 = no movement, 1 = slight movement, 2 = sits with assistance, 3 = sits alone, 4 = weak hop, 5 = normal hop). After 96 hours animals were euthanized, and spinal cords were harvested for histologic examination. The nonparaplegic animals in group I had a mean Tarlov score of 1.5, whereas those in group III had a mean score of 3.4. Histologic studies on spinal cord tissue revealed no significant differences between the study groups. CONCLUSIONS: These data demonstrate that administration of regional adenosine attenuates ischemic injury associated with aortic occlusion in this experimental model.
Adenosine↗
Reduced-size porcine lung transplantation: long-term studies of pulmonary vascular resistance.
The use of isolated adult lobes for pediatric lung transplantation has recently been reported and could potentially help alleviate the profound pediatric donor lung shortage. However, the effect of chronic denervation on pulmonary vasculature of isolated mature lobar transplants is not well understood. Previously, we reported that chronic denervation of the immature porcine lobe results in abnormal pulmonary vascular compliance. We now present studies of long-term pulmonary hemodynamics in young pigs 12 weeks after transplantation of a reduced-size mature left lower lobe. Resting pulmonary vascular resistance of the transplanted mature lobes was similar to that of innervated lobes of age-matched controls. In addition, pulmonary vascular resistance of the transplanted mature lobes did not rise abnormally in response to increased flow caused by clamping the contralateral pulmonary artery. We conclude that denervation of the mature porcine lobe does not result in abnormal pulmonary vascular resistance. In addition, vascular compliance of reduced-size mature porcine lobar transplants is superior to that of denervated reimplanted immature lobes. These findings suggest a deleterious effect of denervation on pulmonary vascular development of the growing porcine lung.
Animals↗
Pleuroperitoneal shunts for refractory chylothorax after operation for congenital heart disease.
Between 1980 and 1990, 10 of 12 children with a symptomatic chylothorax after operation for congenital heart disease failed to respond to traditional medical therapy (thoracentesis, tube thoracostomy, low-fat diet). All 10 patients underwent placement of a pleuroperitoneal shunt, with complete resolution of the chylothorax in 9 patients (90%). Cardiac catheterization, performed before placement of the pleuroperitoneal shunt in 5 patients, demonstrated elevated right atrial pressure in all patients (range, 10 to 25 mm Hg). The pleuroperitoneal shunt functioned effectively in 4 patients with moderately elevated right atrial pressures (range, 10 to 16 mm Hg; median, 13.5 mm Hg) but not in 1 patient with a right atrial pressure of 25 mm Hg. Pleuroperitoneal shunting as treatment for chylothorax after operation for congenital heart disease is safe and effective, even in the face of moderate elevations in right atrial pressure.
Chylothorax↗
Does a posterior aneurysm increase the risk of endocardial resection?
The bias has been that the ideal anatomic circumstance for endocardial resection is the anterior left ventricular location. Posterior left ventricular aneurysms have been thought to be problematic to map and more difficult to close, and possibly to have a different substrate for ventricular tachycardia. To address this problem, we retrospectively reviewed the cases of 110 consecutive patients who underwent sequential endocardial resection for ventricular tachycardia between 1983 and 1991. Ninety-six patients had an anterior aneurysm, and 14 patients had a posterior aneurysm or infarct. Operative survival and 5-year survival were very similar between the two groups (p = not significant). A positive postoperative electrophysiological study was present in 11% of the anterior group versus 14% of the posterior group (p = not significant). There was a significantly greater incidence of mitral valve replacement in the posterior group, and we believe this was most likely due to frequent localization of the arrhythmia to the papillary muscle. Otherwise, patients with a posterior aneurysm or infarct had surgical results equivalent to those in patients with an anterior location. As long as there is a discrete aneurysm or infarct, endocardial resection is a safe and effective therapeutic procedure for ventricular tachycardia.
Endocardium↗
Transhiatal esophagectomy: a safe alternative for selected patients.
One hundred one consecutive patients underwent an esophagectomy with gastric interposition for benign and malignant processes from January 1982 through July 1990. Seventy-seven underwent transhiatal esophagectomy and 24, transthoracic esophagectomy. Multivariate analysis was performed comparing the hospitalization experience of the two groups. There was no significant difference found between the mean intraoperative blood loss for transhiatal esophagectomy (770 +/- 105 mL) and that of transthoracic esophagectomy (700 +/- 175 mL). There was a significant difference between operative time, with transhiatal esophagectomy averaging 5.4 hours and transthoracic esophagectomy averaging 7.3 hours. Postoperative stay was not significantly different although there was a wide range of values for the transthoracic esophagectomy group. An 8% operative mortality was experienced by both groups. There were a significant number of minor anastomotic leaks at the cervical anastomotic level for the transhiatal esophagectomy group, but all responded to nonoperative management. The highest morbidity and mortality were seen in the subgroup of transhiatal esophagectomies done for laryngocervical malignancies. The lowest morbidity and mortality were seen in the subgroup of 12 patients who underwent transhiatal esophagectomy for nonmalignant esophageal conditions. Transhiatal esophagectomy appears to be a safe alternative for early intrathoracic esophageal malignancies at any level, for bulky distal esophageal lesions, and for benign conditions requiring total esophagectomy.
Blood Loss, Surgical↗
Successful treatment of postoperative chylothorax using an external pleuroperitoneal shunt.
We report 3 patients with chylothorax who were successfully managed as outpatients using external pleuroperitoneal shunts. This external shunt has the advantage over subcutaneously placed shunts of pumping large volumes of fluid with each compression of the pumping chamber, of not causing the discomfort associated with pumping a subcutaneous chamber, of not becoming difficult to find in the subcutaneous space, and of being constructed of larger components which do not kink or become easily clogged with fibrinous debris.
Adult↗
Effects of in vivo cyclosporine administration on endothelium-dependent responses in isolated vascular rings.
BACKGROUND: Although in vitro studies suggest that cyclosporine (CSA) reduces endothelium-dependent relaxation (EDR), controversy still remains regarding the effects of in vivo CSA treatment. The lack of correlation between CSA dosages and therapeutic efficacy has led to an increased emphasis on the monitoring of CSA blood levels in clinical immunosuppression. We therefore studied the effects of in vivo administration to rats of a therapeutic level of CSA on endothelium-dependent vascular reactivity using isolated vascular rings obtained from these animals. METHODS AND RESULTS: Thoracic aorta vascular rings from adult Sprague-Dawley rats treated with subcutaneous injections of CSA (5 mg/kg/day) for 7 and 21 days were suspended in Krebs buffer containing indomethacin and tested for EDR to methacholine (1 x 10(-7) to 5 x 10(-5) M) and for endothelium-independent relaxation (EIR) to nitroprusside (5 x 10(-6) M). Mean whole blood CSA trough levels were 978 +/- 287 and 2,865 +/- 379 ng/ml for the 7- and 21-day groups, respectively. No differences were noted in both EDR and EIR between untreated control rats and the treated groups. Maximal EDR (mean +/- SEM) was 83 +/- 3%, 79 +/- 2%, and 81 +/- 3% for control rats and 7- and 21-day treatment groups, respectively. Relative developed tension (grams) to 5 x 10(-6) M phenylephrine was significantly (p < 0.05) increased in the CSA-treated groups (1.03 +/- 0.01 and 1.08 +/- 0.01 g at 7 and 21 days, respectively, versus 0.73 +/- 0.01 g (p = NS) for untreated controls). Minimal endothelial disruption was evident on scanning electron microscopy in the CSA-treated animals. CONCLUSIONS: We conclude that CSA-induced vascular dysfunction may be in part a result of an increased sensitivity to direct vasoconstriction rather than of an attenuation of endothelium-dependent relaxation.
Animals↗
Growth potential of porcine reduced-size mature pulmonary lobar transplants.
The use of mature pulmonary lobes for pediatric lung transplantation has recently been described. Successful application of this technique could help alleviate the pediatric donor lung shortage. Whether an already mature lobe can grow by forming new alveolar units after transplantation into a developing recipient is not known. We therefore measured functional residual capacity, fixed lung volume and weight, alveolar size and air space volume percent, and total number of alveoli in mature left lower lobe porcine lung transplants 12 weeks after transplantation into growing piglets. Comparisons were made with nontransplanted mature left lower lobes to determine if functional or morphologic growth had occurred after transplantation. The transplanted and control lobes were all taken from 6-month-old animals (mean body weight 105 +/- 4 kg). Recipients of the transplanted lobes were 9 weeks old and weighed 22 +/- 2 kg. By the end of the 12-week holding period, the recipient animals increased their body weight approximately fourfold (85 +/- 4 kg). No significant differences were seen in functional residual capacity or morphologic analysis of total alveolar number and alveolar size between the transplanted and nontransplanted lobes (p = not significant). Although the reduced-size mature porcine lobar transplants did not display a significant increase in either functional residual capacity or total alveolar number, there was significant growth of the transplanted mature lobes as determined by fixed volume and total lobar weight (p < or = 0.05 versus control animals).
Animals↗
Weight is not an accurate criterion for adult cardiac transplant size matching.
Owing to the limited availability of donor hearts, standard donor criteria for heart size matching need to be reexamined. The current practice at most centers is to match the donor's body weight to within +/- 20% of the recipient's. Our hypothesis was that minimal differences exist in heart sizes of the adult donor population, and therefore, the donor pool could be expanded for any given patient. M-mode echocardiographic measurements of left and right ventricular internal dimensions, left ventricular mass, and percent fractional shortening were reviewed in 235 normal adult subjects (101 men, 134 women). Low correlation coefficients and a high degree of variance were consistently observed between cardiac parameters and body size. There were no significant differences in left ventricular internal dimension when women weighing 40 to 109 kg were compared with men statistically different among men weighing 50 to 99 kg. No difference was noted in right ventricular size among men and women. Echocardiography is a simple and accurate technique to assess cardiac dimensions. Body weight does not correlate well with adult cardiac size and should not be used as an exclusion criterion for a donor heart.
Body Height↗
Denervation of transplanted porcine lung causes airway obstruction.
Lung transplantation can be complicated by a form of small airway obstruction known as bronchiolitis obliterans. We tested the hypothesis that lung denervation causes small airway obstruction in young pigs (10 +/- 1 weeks). Control pigs had an innervated native lobe, and study pigs had either a denervated native lobe or a denervated transplant lobe. Transplanted pigs received standard immunosuppression. At 10 weeks we measured isolated left lobe pulmonary mechanics. Dynamic resistance in both study groups was significantly higher than in the lobectomy group, whereas dynamic compliance in both study groups was significantly lower than in the lobectomy group. No significant difference in resistance or compliance was noted between the transplant and reimplant groups. Histologic changes consistent with rejection were noted in the transplant lobes. We conclude that the small airway obstruction noted in this model is due to operative denervation rather than to immunosuppression or rejection.
Animals↗
Reducing postischemic paraplegia using conjugated superoxide dismutase.
Paraplegia after thoracic aortic aneurysm repair has an incidence of 2.2% to 24%. Oxygen-derived free radicals after reperfusion of an ischemic spinal cord may be partly responsible for neuronal destruction. We studied the effects of polyethylene glycol-conjugated superoxide dismutase (PEG-SOD), a free radical scavenger, as a way of increasing spinal cord tolerance to ischemia. Thirty rabbits underwent 40 minutes of aortic occlusion (a known model of paraplegia). Ten of these animals received 25,000 U/kg of PEG-SOD 24 hours before aortic occlusion and two additional doses of 10,000 U/kg, one before and one subsequent to spinal ischemia. Ten animals received superoxide dismutase in the same dosages as those receiving PEG-SOD. Ten control animals received placebo. All animals were studied for 96 hours, at which time a final neurological examination was performed and the results were recorded. Of the 10 animals treated with PEG-SOD, 2 were completely paralyzed whereas 8 had less (7) or no (1) neurological impairment. Eight of the 10 control animals and 9 of the 10 animals receiving superoxide dismutase were completely paralyzed. None of the control animals or animals receiving superoxide dismutase had a normal neurological examination (p less than or equal to 0.05). Treatment with PEG-SOD before and during occlusion increased the rabbit spinal cord tolerance to a 40-minute ischemic insult. Scavenging free radicals may lessen experimental spinal cord injury.
Animals↗
The risk of axillofemoral bypass grafting for acute vascular occlusion.
The hypothesis of the present study is that axillofemoral bypass grafting for acute vascular occlusion has results significantly inferior to an elective procedure. We reviewed 53 patients undergoing primary axillofemoral bypass grafting at the University of Virginia from 1984 to 1989. We found that patients who were admitted with acute vascular occlusion had a higher incidence of perioperative complications (63% vs 26%, p = 0.001), perioperative mortality (26% vs 3%, p less than 0.05), lower graft patency at 1 year (60% vs 90%, p less than 0.05), lower rate of freedom from reoperation in first year (50% vs 82%, p less than 0.01), and lower rates of limb salvage (76% vs 94%, p less than 0.05) than patients undergoing axillofemoral bypass grafting for chronic symptoms or conditions. These two groups did not differ in any of the other risk factors or perioperative characteristics examined. We conclude axillofemoral bypass grafting performed for indications other than acute vascular occlusion is associated with acceptable morbidity, mortality, graft patency, and limb salvage rates.
Acute Disease↗
Atypical presentation of chylothorax following pharyngolaryngectomy with esophagectomy and gastric interposition.
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Chylothorax↗
The influence of preoperative radiation therapy on morbidity and mortality for transhiatal esophagectomy.
To assess the morbidity and mortality of preoperative radiation therapy (RT), the authors reviewed 37 consecutive patients who underwent transhiatal esophagectomy for carcinoma of the esophagus. Twelve patients received no RT, 13 patients received RT only to the neck, and 12 received RT to the chest (three of these received radiation therapy to the chest and neck). Preoperative chest RT did not significantly increase postoperative fistula formation but was associated with significantly higher operative mortality, overall complication rate, and time on ventilators than either the patients receiving neck RT alone or no RT (P less than 0.05). Postoperative hospital stay was longer and intraoperative blood loss greater for the chest RT group compared to those with no RT (P less than 0.05). Neck RT did not result in these complications (P = NS). The authors conclude that preoperative chest RT is associated with significant postoperative morbidity and mortality.
Adult↗
Results and complications of angioplasty in aortoiliac disease.
Percutaneous transluminal angioplasty was used to treat 340 aortoiliac lesions in 200 patients who were followed for as long as 90 months (mean, 28.7 months; median, 23 months). The initial success rate was 94.7% for lesions and 93.0% for patients. The indications for percutaneous transluminal angioplasty included claudication in 117 patients (58.5%), rest pain or ischemic night pain in 47 (23.5%), limb salvage in 33 (16.5%), and aiding in wound healing in three (1.5%). In the series, 70% of the patients had two or more cardiovascular risk factors. Angioplasty was initially unsuccessful in 14 patients, and 10 patients were lost to follow-up. Follow-up was obtained in 176 patients. The long-term results were analyzed using the life table method to determine cumulative patency. Fourteen patients were considered failures because of recurrent disease or symptoms. The projected 7.5-year cumulative patency rate was 85%. When the response to redilatation was considered, the projected 7.5-year cumulative patency rate was 92%. The results indicate that percutaneous transluminal angioplasty can successfully correct aortoiliac lesions and provide a long-term benefit for as long as 7.5 years.
Angioplasty, Balloon↗