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Biomedical subjects

L Wexler

Publications and source records attributed to L Wexler.

At least 55 records · Page 3Linked to original sources
PubMed1991

Variations in length of stay and outcomes for six medical and surgical conditions in Massachusetts and California.

OBJECTIVES: --To determine the extent to which interinstitutional variations in length of stay are explained by differences in patient characteristics and to determine whether patients in hospitals with shorter lengths of stay had worse outcomes. DESIGN: --We reviewed patients' medical records and surveyed patients between 3 and 12 months after hospital discharge using a questionnaire. SETTING: --Six teaching hospitals in California and Massachusetts. PATIENTS: --A cohort of 2484 selected patients who had been hospitalized for acute myocardial infarction or to rule out acute myocardial infarction, coronary artery bypass graft surgery, total hip replacement, cholecystectomy, or transurethral prostatectomy. Between 73% and 84% of the patients with each condition completed a follow-up questionnaire. OUTCOME MEASURES: --In-hospital complications, deaths, length of stay, functional status after hospital discharge, readmission, and patient satisfaction with hospital care were analyzed. RESULTS: --Significant interinstitutional differences in length of stay were noted for all conditions except rule-out acute myocardial infarction. Statistical adjustment for case-mix differences accounted for most of the interinstitutional differences in length of stay for total hip replacement but explained little of the differences in the other conditions. When we controlled statistically for other predictors, length of stay did not have a significant impact on deaths, functional status after hospital discharge, the probability of readmission, or patient satisfaction with hospital care. CONCLUSION: --More research is needed to determine the medical practices that are related to variations in lengths of stay. Routinely available outcome data may help preserve quality in the face of efforts to decrease costs by effecting more standardized practices of care.

Adult↗
PubMed1991

Frequency and mechanism of bradycardia in cardiac transplant recipients and need for pacemakers.

Orthotopic cardiac transplantation is occasionally complicated by unexplained bradyarrhythmias. Sinus node injury as a consequence of operation or acute rejection has anecdotally been linked to the development of bradycardia early after transplantation. These arrhythmias are empirically managed by pacemaker implantation, the indications for which remain poorly defined. This retrospective study examined the 20-year experience of our institution with bradyarrhythmias after transplantation to determine the predisposing factors and indications for pacemaker implantation. Forty-one of 556 patients in our cardiac transplant program (7.4%) received permanent pacemakers between 1969 and 1989. The predominant rhythm disturbances were junctional rhythm (46%), sinus arrest (27%) and sinus bradycardia (17%). Most patients were asymptomatic (61%), and presented in the early post-transplant period (73%). Four possible predisposing factors were evaluated: (1) graft ischemic time, (2) rejection history, (3) use of bradycardia-inducing drugs, and (4) anatomy of blood supply to the sinoatrial (SA) node. No significant differences existed between patients with and without pacemakers with regard to the first 3 variables. However, after transplantation angiograms showed that prevalence of abnormal SA nodal arteries was greater in patients with than without pacemakers (p less than 0.02). Pacemaker follow-up at 3, 6 and 12 months showed persistent bradycardia (60 to 90 beats/min) in 88, 75 and 50% of patients, respectively. The most common pacemaker complication (15%) was lead displacement at time of biopsy. These results suggest that disruption of the SA nodal blood supply may be an important predisposing factor in the development of bradycardias.

Adolescent↗
PubMed1991

PAH extraction and estimation of plasma flow in diseased human kidneys.

We have analyzed the efficiency with which p-amino-hippuric acid (PAH) is extracted (EPAH) by patients with healthy kidneys (n = 13) or kidneys damaged by chronic cyclosporin nephropathy (n = 21) or primary glomerulopathy (n = 12); respective values (mean +/- SE) for EPAH were 0.87 +/- 0.03, 0.77 +/- 0.03, and 0.69 +/- 0.04. Judged by a 131I-hippuran-to-PAH clearance ratio of 0.75 +/- 0.05, extraction ratio of hippuran was less efficient than EPAH in three glomerulopathic patients. A direct relationship was defined between EPAH and glomerular filtration rate (GFR) (r = 0.54) or calculated efferent oncotic pressure (IIE; r = 0.41, P less than 0.01). Curve fitting by means of quadratic spline functions revealed GFR and IIE to be additive in predicting EPAH (R2 = 0.45). Linear model prediction methods and a sample reuse technique failed to predict EPAH reliably from GFR and preglomerular oncotic pressure (IIA); however, 95% prediction intervals exceed 0.30 EPAH units in width. We conclude that oncotic pressure (presumably reflecting albumin concentration) along with GFR is predictive of EPAH depression in humans with chronic renal disease. However, even sophisticated curve-fitting techniques are too imprecise for accurate prediction of EPAH in a given individual. We submit that renal venous sampling to determine EPAH continues to be necessary for the accurate determination of the rate of plasma flow in the injured human kidney.

Adolescent↗
PubMed1990

Monorail system for percutaneous repositioning of the Greenfield vena caval filter.

The authors describe a technique for removing or repositioning a malpositioned Greenfield inferior vena caval filter. A "monorail" system was used, in which a wire was passed from the femoral vein through the apical hole in the filter and out the internal jugular vein; the wire was held taut from above and below and thus facilitated repositioning or removal of the filter. The technique was used successfully in two cases.

Adult↗
PubMed1989

Angiographic implications of cardiac transplantation.

Coronary vascular disease in the cardiac transplant recipient has become the third most frequent cause of death or retransplantation after infection and acute rejection. A unique pattern of concentric fibrointimal thickening develops within 1 year of cardiac transplantation; however, it is relatively inapparent on routine arteriography. The disease progresses primarily in distal vasculature, leading to progressive occlusion. Angiographically discrete lesions associated microscopically with advanced atherosclerotic plaques frequently occur in the more proximal vessels often associated with thrombus. The number of rejection episodes is somewhat predictive of the development of transplant coronary disease. Annual arteriograms performed in cardiac transplant recipients have revealed several distinctive angiographic features that include clockwise rotation of the heart, presence of coronary arterial-cameral fistulae, presumably resulting from right ventricular endomyocardial biopsy specimens and collateralization of the brachial anastomosis from coronary atrial branches. It is concluded that serial angiography in cardiac transplant recipients is important in the early detection of progressive graft atherosclerosis, a process that is clinically silent until such time as overt heart failure or cardiogenic shock occurs.

Coronary Angiography↗
PubMed1989

Natural history of the false channel of type A aortic dissection after surgical repair: CT study.

To evaluate the false channel after surgical repair of a type A aortic dissection, postoperative computed tomographic (CT) scans were retrospectively reviewed in 33 patients. Initial CT demonstrated persistence of a double channel distal to the site of surgical repair in 26 patients (79%). In four of these patients serial CT demonstrated enlargement of the false channel, a finding that contributed to the decision to repeat surgery. Progression of thrombus was noted in five patients. Peripheral calcification within the aortic wall of the false channel, presumably located on the "pseudointima," was found in six patients. Because of the progressive nature of type A dissections in the postoperative period, serial CT examinations can provide important information on patients who have undergone surgical correction of a type A dissection.

Adult↗
PubMed1989

Pull-through approach to percutaneous angioplasty of totally occluded common iliac arteries.

A method has been developed to increase the probability of success of percutaneous transluminal balloon angioplasty of total occlusions of the common iliac artery when conventional methods have failed. In 10 patients with a totally obstructed iliac artery, a guide wire was passed through a catheter placed from the contralateral side around the aortic bifurcation and antegrade through the total obstruction. The end of the wire was either snared by a retrieval basket or guided through a sheath in the ipsilateral common femoral artery, thus providing a firmly anchored pathway for subsequent manipulations. Balloons were then inserted retrograde through both common femoral arteries and dilated. In the first five patients, ipsilateral retrograde passage of a guide wire had failed despite multiple attempts with a variety of devices. In the other five patients, the contralateral antegrade approach was used initially. The new method was successful in all 10 patients with totally obstructed common iliac arteries.

Angioplasty, Balloon↗
PubMed1987

Diagnostic challenges following cardiac transplantation.

It is now almost two decades since the first human cardiac transplantation was performed. Recipients will require close follow-up by their referring physicians outside of the main referral centers. This article is intended to assist the referring physician in choosing the most appropriate diagnostic studies throughout the posttransplant period.

Biopsy↗
PubMed1985

Optimizing strategies for laser angioplasty.

The intrinsic optical properties of normal and diseased vascular tissues and their interaction with continuous wave (cw) and pulsed laser light were investigated to determine the optimal source for laser angioplasty. Both intima and atheromatous plaque demonstrated increasing spectral absorbance at shorter wavelengths (in the near ultraviolet). The relative differences in absorbance between diseased and nondiseased tissues were not sufficient to allow selective ablation of plaque. Atheromatous plaque appears more resistant than normal intima to damage by cw argon laser. The interaction of tissue with a high-power, pulsed ultraviolet laser showed a nonlinear response as pulse repetition rate and pulse energy were varied. From theoretical considerations and our experimental results, we propose that a pulsed ultraviolet laser with 50 millijoules of power per pulse and a repetition rate of 10 pps would be safer and more effective for recanalization than the cw argon laser.

Angioplasty, Balloon↗
PubMed1985

Percutaneous transluminal laser angioplasty for treatment of peripheral vascular disease. Clinical experience with 16 patients.

Percutaneous transluminal laser angioplasty of the peripheral arteries was performed in 16 patients with pain at rest, objective evidence of severe peripheral ischemia, conditions requiring amputation, and/or medical contraindications to surgery. In 14 patients the ipsilateral femoral artery was entered in an antegrade direction using the Seldinger technique, base-line angiograms taken, and laser angioplasty performed using argon ions transported to the target site by a 400-mu quartz fiber. Patency was established in 50% of cases and correlated directly with both total energy delivered and time and power per exposure: the lower the energy, the higher the patency rate. Complications included spasm, pain, and mechanical or laser perforation. The authors conclude that while percutaneous transluminal laser angioplasty of peripheral arteries using argon radiation is possible in man, its clinical value has not been established.

Adult↗
PubMed1985

Digital subtraction angiography of coronary grafts: optimization of technique.

Forty patients who had undergone coronary artery bypass surgery were studied with digital subtraction angiography (DSA) to develop an outpatient screening technique for coronary artery bypass graft visualization. Of 103 grafts in 40 patients, 101 were seen: 95 were clearly patent and in six the stump of an occluded graft was seen. Of 32 grafts seen in 14 patients using intraarterial DSA, only 13 (41%) were demonstrated using intravenous DSA. Intraarterial DSA is an effective screening procedure to determine bypass graft patency. However, volumes of 40-45 ml of 76% contrast medium injected at rates of at least 20 ml/sec must be used for each injection to obtain a diagnostic image, and since each projection is complementary and contributes some information, several injections must be used to complete an examination.

Angiography↗
PubMed1983

Evaluation of peripheral vascular disease using digital subtraction angiography.

Intravenous digital subtraction angiography (DSA) facilitates imaging of peripheral arteries and bypass grafts on an outpatient basis. Forty-five patients underwent intravenous peripheral angiography, 16 following placement of bypass grafts. Complex oblique and sagittal angulations optimize visualization of bifurcations and overlapping vascular structures. Reprocessing techniques using integrated masks and contrast images allow for diagnostic delineation of fine vascular detail. This is a practical, noninvasive, well tolerated method for both diagnostic screening and follow-up evaluation of patients with peripheral vascular disease.

Angiography↗