Biomedical subjects

L D Kaelin

Publications and source records attributed to L D Kaelin.

9 recordsLinked to original sources

PubMed2001

A model for evaluation of arterial thrombosis following interventional procedures.

A model to assess thrombus formation following vascular injury was evaluated using various interventional systems. The model consisted of a 'stretchable' shunt box that served as an arteriovenous shunt between the carotid artery and jugular vein in dogs. Arterial homografts obtained from both carotid and femoral arteries were mounted between two plastic connectors attached to either side of the shunt box. The opposing walls of the shunt box were then stretched apart to achieve the original length of the arteries. The arterial side of the box was connected to the ipsilateral carotid artery and the venous side was connected to the contralateral jugular vein. Haemostasis valves were placed at the exit ports on the venous side of the shunt box. These were used as an access to the various interventional catheters into the lumens of the homografts. Interventions were performed prior to initiating blood flow. After the interventions, 111indium-labelled platelets were injected on the arterial side of the shunt box and arterial blood flow initiated across the shunt. After one hour of circulation through the shunt box, the blood flow was interrupted, and the homografts were perfusion-fixed with glutaraldehyde and segments removed for radioactive counts and processed for histology. This shunt box was then used to compare platelet adhesion and thrombus formation after balloon angioplasty (BA) to direct laser (LA) and laser-thermal angioplasty (LTA). A total of 28 arteries were used from seven dogs. In each experiment, one homograft was used as control, and three other homografts were treated with either BA, LA or LTA. Following the interventions, 111indium-labelled platelets were injected and circulated for one hour using the dog's native circulation. Labelled platelet counts for BA (19102+/-4869/cm2; mean +/- SE) were significantly greater than LA (7038+/-980/cm2), thermal LTA (5189+/-1961/cm2), and control (1575+/-541/cm2), respectively (p<0.05, ANOVA). Histology examination showed few platelets at LA, LTA and control sites whereas extensive platelet adhesion was noted at BA treated sites. The model provided a means to conduct simultaneous comparison of several interventions under similar conditions. In this case thermal treatment of the arterial homografts had the least amount of platelet adhesion.

Angioplasty, Balloon↗

PubMed1997

Prevention of postoperative pericardial adhesions using tissue-protective solutions.

Repeat cardiac surgical procedures are associated with increased technical difficulty and risk because of the previous formation of dense adhesions between the heart and the surrounding tissues. Dilute solutions of sodium hyaluronic acid (NaHA) and carboxymethyl cellulose (CMC) have been shown to prevent postoperative abdominal and pelvic adhesions and could therefore potentially inhibit adhesion formation following cardiac surgery. Adhesion prevention using 0.1% NaHA, 0.4% NaHA, or 0.1% CMC solutions was examined in a canine abrasion/desiccation pericardial adhesion model (5 animals/group) and compared to 10 animals treated with Ringer's lactate (RL) solution alone. The pericardium and heart were coated with 25 ml of test or control solution prior to and after pericardiotomy, after controlled gauze abrasion, after 30 min of desiccation, and prior to closure. At 6 weeks, animals were reexplored and adhesions were scored in a blinded manner by three to four surgeons using a 0-4 scale. Scores of 2 or greater were considered clinically significant. Mean adhesion scores from the left epicardium were 0.0 in animals treated with 0.1% NaHA, 0.6 in animals treated with 0.4% NaHA or 1% CMC, and 2.3 in animals treated with RL (P < 0.05 Duncan's ANOVA). In addition, none of the animals treated with 0.1% NaHA, 20% of the animals treated with 0.4% NaHA, and 20% of the animals treated with 1% CMC had clinically significant adhesions, whereas 80% of animals treated with RL had such adhesions. Sodium hyaluronic acid and CMC solutions, used as tissue coatings during cardiac surgery, inhibit the formation of undesired postoperative adhesions. Application of these biocompatible polymer solutions during surgery could reduce the technical difficulty and risk of repeat cardiac surgical procedures.

Animals↗

PubMed1996

Peripheral artery recanalization in humans using balloon and laser angioplasty.

The treatment of patients with complex peripheral arterial disease and those who have had previous unsuccessful attempted revascularization procedures can be clinically challenging. Initial treatment was begun using therapy by percutaneous balloon and laser angioplasty, then proceeding to bypass surgery if severe ischemia persisted. Both percutaneous and cut-down approaches were used to access totally occluded arteries. An attempt was made to cross the occlusion mechanically with either a guide wire or an activated laser probe. If laser recanalization was not successful, the patient underwent bypass surgery or was managed with medication unless an amputation was necessary. Following initial screening of 381 patients, 115 procedures were performed on 103 patients. In 31 procedures (28 patients), only balloon angioplasty was performed. In 84 procedures (75 patients), laser recanalization was attempted: 55 percutaneously and 29 by cut-down. Overall technical success (crossing the obstruction without perforation) was 86/115 (75%). Technically successful procedures were characterized by shorter arterial occlusions than were technical failures (8.4 +/- 1 cm vs. 14.3 +/- 1.9 cm; p < 0.004). Clinical success (residual stenosis < 50%, symptom relief, improved ankle brachial index > or = 0.15, and no complications) was achieved in 22/31 (71%) of balloon angioplasty procedures alone. The stenoses decreased from 98 +/- 4% to 31 +/- 24%, p < 0.00001. Combined percutaneous laser and balloon angioplasty had a technical success of 36/55 (65%). Stenoses were reduced from 99 +/- 2% to 56 +/- 14% after laser angioplasty, to 30 +/- 15% after balloon angioplasty, p < 0.0001. Laser angioplasty performed via a cut-down had a clinical success of 9/29 (31%). However, major complications were rare. Device staging for treatment of peripheral vascular disease provides additional options for patients who are at high surgical risk and/or in whom standard therapy has failed.

Adult↗

PubMed1993

Limitations and pitfalls of laser angioplasty.

Overall, the initial and long-term results of LABA have been disappointing. Poor initial recanalization rates and high restenosis and hemodynamic failure rates have caused investigators to reevaluate the indications for LABA. This reevaluation has resulted in an appropriate limitation of the indications for LABA. At present, LABA is probably indicated only for the treatment of patients with symptomatic, isolated arterial occlusions in whom conventional balloon angioplasty cannot be done because mechanical recanalization using a guidewire is not possible. Other uses of LABA in patients with peripheral vascular disease are discouraged and should be considered experimental. New innovations in technology, including improved arterial imaging techniques and better laser delivery systems, are required before LABA can become a standard therapy for the treatment of patients with peripheral vascular disease. A search for an "ideal" laser wavelength for arterial recanalization is futile until these developments occur. Once these innovations are in use, laser angioplasty may be an important technique in the treatment of peripheral vascular disease. This potentially valuable tool for the vascular surgeon should not be abandoned. Rather, it should be laid aside until it is better developed.

Angioplasty, Balloon, Laser-Assisted↗

PubMed1992

In vitro laser recanalization of chronically occluded prosthetic grafts.

Polytetrafluoroethylene (PTFE) and Dacron grafts were implanted in canine femoral and carotid arteries using PTFE and Prolene suture, respectively. Arteries containing occluded grafts were explanted and laser recanalization was attempted in vitro. Laser recanalization was successful in 78% of PTFE grafts compared to 30% of Dacron grafts. Recanalization was complete (residual stenosis less than 5%) in opened PTFE grafts, whereas residual stenosis averaged 60% in recanalized Dacron grafts. PTFE graft/PTFE suture anastomotic tensile strength was unchanged after recanalization, while Dacron graft/Prolene suture anastomotic tensile strength decreased significantly. In addition, anastomotic bursting pressure was significantly higher for lased PTFE grafts with PTFE sutures (300 mg Hg) compared to lased Dacron grafts with Prolene sutures (70 mm Hg). Chronically occluded PTFE grafts with PTFE suture can be safely and effectively opened by laser recanalization. In contrast, attempted laser recanalization of Dacron grafts sutured with Prolene suture is seldom successful, significantly weakens the graft artery anastomosis, and should be avoided.

Anastomosis, Surgical↗

PubMed1992

Routine reimplantation of patent inferior mesenteric arteries limits colon infarction after aortic reconstruction.

Ischemic colitis resulting in colonic infarction after aortic reconstruction is a highly lethal complication. Reimplantation of all patent inferior mesenteric arteries should improve this problem but can be justified only if the procedure is effective and safe. To investigate this, 337 aortic reconstructions done between July 1982 and May 1989 were reviewed. Patent inferior mesenteric arteries had been reimplanted when possible during 151 aortic reconstructions done between April 1986 and May 1989. Before this, patent inferior mesenteric arteries were selectively ligated on the basis of intraoperative bowel inspection, colonic mesenteric Doppler signals, and inferior mesenteric arteries stump pressures during 186 aortic procedures. No patient had colonic infarction as a result of ischemia during the period in which patent inferior mesenteric arteries were reimplanted if possible. In contrast, five patients (2.7%; p less than 0.05) had colonic infarction and perforation during the period of selective inferior mesenteric arteries ligation resulting in four deaths. The operative mortality rate was less during the period of inferior mesenteric arteries reimplantation (4.0% vs 14.5%; p less than 0.05), and transfusion requirements were unchanged. Thus routine reimplantation of patent inferior mesenteric arteries limits colonic infarction and operative deaths after aortic reconstruction.

Aged↗

PubMed1990

Laser recanalization in high risk patients.

Laser recanalization was attempted in 13 patients in whom the risk of surgical therapy was increased by severe angina, infection, absent venous conduit, or recent deep venous thrombosis, and in 4 patients at high risk for limb loss due to severe infrapopliteal arterial occlusive disease. Total occlusions of the superficial femoral, tibial, or peroneal arteries were treated. Recanalization was accomplished using Argon laser power and a Spectraprobe-PLR. Two patients also required common femoral artery endarterectomy to improve inflow. Laser recanalization was successful in 9 patients (53%), and 8 (47%) had relief symptoms. None of the 4 patients with tibial and peroneal artery occlusion had successful recanalization or limb salvage. Restenosis or reocclusion developed in 4 patients during the first year after successful recanalization, but only 1 had recurrent symptoms. Limb salvage was initially achieved in 5 of 8 recanalization failures by surgical reconstruction but 3 developed graft infections requiring graft removal in 2 and amputation in 1. Thus, laser recanalization can accomplish limb salvage in selected patients whose medical or surgical risks complicate arterial bypass surgery.

Adult↗

PubMed1990

The effect of plaque composition on laser recanalization.

Laser recanalization using metal-capped laser fibers and continuous-wave laser energy occurs by thermal ablation of atherosclerotic plaque. Different types of plaque respond differently to laser energy and plaque composition may be an important determinant of the success of laser recanalization. To investigate this hypothesis, 16 patients with symptomatic arterial occlusions in the mid and distal superficial femoral artery underwent B-mode ultrasound arterial imaging prior to attempted argon laser recanalization. The composition of the occlusions was classified as soft (echogenicity less than the adjacent arterial wall), dense (echogenicity equal to the adjacent arterial wall), or calcified (echoreflective). Recanalization was successful in 100% (8/8) of patients with soft occlusions versus 38% (3/8) with dense or calcified occlusions (P = 0.01). Thus, plaque composition as assessed by B-mode ultrasound imaging appears to be an important predictor of the success or failure of arterial recanalization using a thermal laser probe.

Aged↗

PubMed1986

Malignant ascites. Clinical and experimental observations.

Malignant ascites formation is a grave prognostic sign, but palliative efforts seem justified in some patients. Lack of knowledge concerning the natural history of this process hinders the choice of therapeutic options. Over 5 years, 107 patients with untreated malignant ascites were reviewed to define their survival. Pancreas (20), ovary (18), and colon (18) were the most frequent tumors, with 52% of patients presenting with ascites at the time of the initial cancer diagnosis. Cytology evaluation of the ascitic fluid was positive for tumor cells in 57% of cases and a high protein content was noted in 65%. Mean survival of the entire series was only 20 weeks from the time of diagnosis of ascites, with tumors of ovarian and lymphatic origin having better mean survivals of 32 and 58 weeks, respectively. Patients with high ascitic protein levels fared better than those with low levels. In an effort to explain this correlation of elevated protein levels and a favorable survival rate, a hypothesis was proposed that certain tumors secrete a factor, which alters vascular permeability and causes fluid accumulation in the absence of lymphatic obstruction. In an experimental rat model of malignant ascites, the intraperitoneal infusion of cell-free malignant ascitic fluid caused an increase in edema formation and a significant increase in capillary permeability to protein in the omentum. This demonstrated change in the leak of protein explains the formation of ascites by some tumors in the absence of tumor obstruction of the draining lymphatics of the peritoneal cavity and suggests another important mechanism in the genesis of malignant ascites.

Adult↗