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Biomedical subjects

H I Machleder

Publications and source records attributed to H I Machleder.

At least 55 records · Page 3Linked to original sources
PubMed1985

Acute renal dysfunction after major arteriography.

The incidence of acute renal dysfunction (ARD) after major arteriography was evaluated by assessment of the change in serum creatinine in 364 patients undergoing arteriography. Major arteriography was defined as abdominal aortography, abdominal aortography with lower-extremity runoff, aortic arch studies, or aortic arch plus selective carotid angiography. The influence of the volume of contrast material received, hydration, and associated risk factors was evaluated. In the entire group, the frequency of postarteriographic ARD was 7.1%. Although most patients recovered, 1.4% required renal dialysis. The frequency of renal dysfunction was significantly higher in patients with preexisting renal disease (14.8%), and 3.7% of these patients went on to require dialysis. In the total group and in those with normal renal function prearteriographically, the frequency of ARD was found to be related to the volume of iodinated contrast material received. Hydration before, during, and after angiography did not prevent this complication. Several risk factors, namely preexisting renal disease, advanced age, volume of contrast material used, type of study performed, diabetes mellitus, and coexistent heart disease were found to be associated with a statistically significant increased risk of postangiographic ARD.

Acute Kidney Injury↗
PubMed1984

Polytetrafluoroethylene grafts as the first-choice arterial substitute in femoropopliteal revascularization.

We studied a series of femoropopliteal bypass operations in which polytetrafluoroethylene (PTFE) grafts were used as the first choice, regardless of the availability of saphenous vein. From Jan 1, 1979 to Dec 31, 1982, 63 PTFE femoropopliteal bypass grafts were placed in 55 patients without exploration of the saphenous vein. Forty-three grafts were placed for limb salvage, and 20 grafts were placed for disabling claudication. Patients were followed up for nine to 53 months (average, 23 months). The operative mortality was 1.8%. There were no infections. The overall patency at 30 months was 76.1%. The 30 months' cumulative patency rate for patients with claudication was 89.3%, and there were no amputations. The cumulative 30-month patency for limb salvage was 70.1%, and there was a limb salvage rate of 81.2%. Because the 30-month results were comparable with reported series using autogenous saphenous vein, we concluded that PTFE conduits may be considered the first-choice arterial substitute for femoropopliteal reconstruction. Until longer follow-ups are available, reversed autogenous saphenous vein should probably be the graft of first choice in younger patients (less than 60 years of age) without coronary artery disease who are undergoing femoropopliteal revascularizations.

Aged↗
PubMed1984

Determinants of failure in the treatment of ruptured abdominal aortic aneurysm.

One must identify those fatal errors in the treatment of patients with ruptured abdominal aortic aneurysms (AAAs) to improve future treatment and reduce mortality. Our vascular registry identified 29 patients with ruptured AAAs who died following admission to the UCLA Hospital, Los Angeles, and the Sepulveda (Calif) Veterans Administration Hospital between 1971 and 1981. Review of the records identified four categories of error that contributed to death. These included failure to proceed with elective aneurysmectomy in 12 patients with known AAAs, error in the diagnosis of aortic rupture that led to delay in getting nine patients to the operating room, intraoperative technical error that produced venous injury in eight patients, and undue delay in anesthetic induction in four patients. Following the outline of a careful treatment approach should further reduce the mortality in the treatment of patients with ruptured AAAs.

Aged↗
PubMed1984

Analysis of femoral artery Doppler signals by LaPlace transform damping method.

The LaPlace transform damping (LTD) method of common femoral artery Doppler waveform analysis is a new method for assessing aortoiliac stenosis. A microcomputer was used to analyze the waveform to determine the value of the damping parameter, which is related to inflow stenosis. The study included 60 limbs with arterial disease and 20 limbs in normal control subjects. With a damping value of 0.60 used as the cutoff point between nonocclusive lesions and iliac stenoses of greater than 50% diameter reduction, we found a sensitivity of 100% and a specificity of 93% (overall accuracy 95%). Unlike Doppler waveform analysis by the pulsatility index method, the accuracy of the LTD method is not affected by occlusion of the superficial femoral artery. The Doppler signal processor and the computer currently used for the LTD analysis are simple to operate and fully suitable for routine use in a clinical vascular laboratory. Our experience indicates that the LTD method of waveform analysis provides the best noninvasive method for detection of significant inflow disease.

Aorta, Abdominal↗
PubMed1984

Bacteriologic and surgical determinants of survival in patients with mycotic aneurysms.

Mycotic aneurysms are a fulminant infectious process frequently resulting in rupture and death if not properly treated. A review of the University of California, Los Angeles, medical records identified 10 patients with extrathoracic, extracranial mycotic aneurysms. In addition, a search of the English literature revealed 178 patients with 243 mycotic aneurysms. These patients were reviewed to identify the aneurysm location, etiology, bacteriology, and modality of treatment in order to determine the relationship between these factors and the outcome. The femoral artery was the most common site (38%), followed by the abdominal aorta (31%). Arterial trauma was the primary etiology in 42% of mycotic aneurysms. In 25% no clear source of infection could be identified. Staphylococcus aureus was cultured from 28% of mycotic aneurysms, and Salmonella from 15%. A trend toward the involvement of more gram-negative aerobes and anaerobes is noted. Aortic aneurysms were repaired with in situ Dacron in 61% of patients with a 32% mortality rate and 16% reinfection rate. Simple ligation of femoral artery mycotic aneurysms resulted in a 34% incidence of ischemia necessitating amputation. Methods of treatment of superior mesenteric, carotid, iliac, and peripheral arteries are also analyzed. On the basis of these data, specific surgical procedures are recommended for the treatment of mycotic aneurysms.

Adolescent↗
PubMed1984

The limitations of predictability of success of femoral-popliteal bypass grafts.

This study was carried out to determine whether we could develop a model to identify predictive factors for success of femoral-popliteal (FP) bypass grafts. In a retrospective review of 199 operations, 24 factors influencing outcome were selected by stepwise logistic regression analysis, a sophisticated, multifactorial computer program. The top five indicators (excluding intraoperative technical problems) were runoff status, previous ipsilateral FP bypass, preoperative prediction of potential amputation level, concurrent proximal vascular reconstruction, and site of the distal anastomosis. We chose to validate the predictive model developed before applying it clinically. Data from 67 subsequent cases were presented to the computer without the known outcome, and the probability of 30-day patency was calculated. The model predicted 11 failures; there were actually eight thromboses in the 67 grafts. However, only three of the failures were predicted correctly, and eight cases of computer-anticipated thromboses were patent at 30 days. The high false positive rate makes the clinical application of the predictive model inappropriate. The success of FP bypass grafts appears to be related to factors that cannot be assessed preoperatively, such as technical problems during surgery. Even those which seem to have a poor runoff and other high-risk factors may succeed; thus an aggressive approach is justified in lower extremity reconstructions.

Blood Vessel Prosthesis↗
PubMed1983

Congenital arteriovenous malformations. The role of transcatheter arterial embolization.

We treated 11 patients with congenital arteriovenous malformations (AVMs) with staged transcatheter arterial embolization of their lesions. In nine patients, the AVM involved an extremity. One patient had multiple pulmonary AVMs, another an AVM of the pancreas. Embolization was performed using polyvinyl alcohol sponge (Ivalon) particles and Gianturco-Wallace colls. Nine patients had a systemic response to embolization, characterized by pain, fever, leukocytosis, and elevated enzyme levels. Complications (three major, two minor) developed in five patients. A total of 28 staged embolizations were performed, with follow-up to 36 months. We found transcatheter embolization a useful palliative therapy in treating congenital AVMs. It should be considered as a therapeutic alternative for patients with unresectable AVMs, those for whom amputation would be required, and those who are otherwise poor surgical candidates.

Adolescent↗
PubMed1983

Cause and noninvasive detection of restenosis after carotid endarterectomy.

The incidence of significant restenosis after carotid endarterectomy was studied with ocular pneumoplethysmography. Of 105 operations, symptomatic restenosis occurred in 4.8 percent and asymptomatic restenosis in 6.6 percent. No preoperative factors were identified to be associated with subsequent recurrence. However, technical problems with the end-point of the endarterectomy were associated with restenosis. Half of the restenoses occurred in the first 6 months of operation. The results focus on the need for special attention to the technical management of end-point problems and the need for early noninvasive follow-up to detect a substantial proportion of early restenoses.

Arterial Occlusive Diseases↗
PubMed1983

Aortic saddle embolus. A twenty-year experience.

Clinical experience with aortic saddle embolus (ASE) is not extensive due to the relative infrequent lodging of emboli at the aortic bifurcation. During the period 1962-1982, 26 patients (mean age, 56 years) were treated at the UCLA Medical Center for ASE and followed from 2 to 158 months (mean, 45 months). These cases were reviewed in order to identify features of diagnosis, anticoagulation, and operation which impact on results. All 26 patients presented with bilateral lower extremity ischemia with or without extension of clot to the iliac bifurcation. Ninety-six per cent of emboli were of cardiac origin and one-third occurred in patients who had previous symptoms of chronic lower extremity ischemia. Rest pain and motor/sensory deficits were main complaints in 92% of the patients, but did not become manifest until more than 6 hours, unlike more distal emboli which have an earlier presentation. Preoperative angiography, even in the patient with a history of claudication, has a small role in planning the surgical approach to patients with ASE and, although performed in 11 patients, it influenced operation in only two. Operation within the "golden period" of 6 hours after embolization did not significantly influence outcome after ASE, since 20 patients were operated on more than 6 hours after embolization, with results similar to six patients who were operated on less than 6 hours after embolization. Early high-dose heparinization, used in all patients and maintained for a mean of 12 days, may have contributed to this effect. In 22 patients (85%) Forgarty catheter extraction via bilateral groin approaches was used with a mortality of 14%; only one death was directly attributed to the catheter embolectomy. In 15% of patients, a direct approach on the aorta was selected with a zero mortality rate. Postoperative functional result was excellent with an amputation rate of only 2% (one limb). Re-embolization occurred in seven patients (27%) after discharge, five of whom had not been maintained on Coumadin and two who were not anticoagulated adequately. The authors conclude that the keys to successful treatment of ASE include high dose heparin which is maintained through the perioperative period, embolectomy without preoperative angiography, and maintenance of long-term oral anticoagulation.

Adult↗
PubMed1982

Natural history of nonstenotic, asymptomatic ulcerative lesions of the carotid artery. A further analysis.

The natural history of 153 asymptomatic, nonstenotic ulcerative lesions of the carotid bifurcation in 141 patients was reviewed. A technique for quantitatively defining small (A), large (B), and compound (C) ulcers was developed. During the course of study, extending up to ten years, 3% of patients with A ulcers, 21% with B ulcers, and 19% with C ulcers had hemispheric strokes without antecedent transient ischemic attacks (TIAs), on the side appropriate to the lesion. The interval annual stroke rate was 4.5% for B ulcers and 7.5% for C ulcers. Because these interval stroke rates are comparable to the 6% annual stroke rate occurring in patients with TIAs, a well-accepted indication for operation, we recommend prophylactic operation for these lesions in good surgical candidates, to be performed by surgeons who have demonstrably low operative stroke rates.

Actuarial Analysis↗
PubMed1982

Transient ischaemic attacks: the static and dynamic morphology of the carotid artery bifurcation.

Studies evaluating the static and dynamic characteristics of the common carotid bifurcation are described. Slow motion angiographic frames, real time B-mode images and time position M-mode tracings have demonstrated appreciable vessel wall motion with an increase in distensibility at the carotid bulb compared to the proximal common carotid artery. Histopathological studies suggest that changes in the carotid artery elastin and collagen structure may contribute to the increased distensibility at the carotid bulb. The presence or absence of a cervical bruit did not correlate with the ultrasonic demonstration of plaque or blood flow turbulence. Mechanical factors relating to the development of symptoms of cerebral ischaemia are discussed.

Auscultation↗
PubMed1982

Femoropopliteal tibial bypass: what price failure?

The consequences of failure in 235 femoropopliteal and femorotibial operations are reviewed and compared with the benefits of success so that an accurate perspective of risk-benefit analysis can be achieved. In 72 operations performed for claudication, 10 grafts thrombosed early. The cost included nine reoperations to achieve eight patent grafts and a 12 day average increase in hospital stay. There were no deaths. The benefit obtained was 70 of 72 (97 percent) asymptomatic limbs. In 163 grafts placed for limb salvage, there were 58 initial thromboses. Reoperation in 28 produced an additional 14 patent grafts. The cost of thrombosis was an increase in mortality from 5.6 to 10.7 percent, a 12 day average increase in hospital stay, and raising of preoperative predicted amputation level from below to above the knee in 11 patients with thrombosed grafts whose distal anastomoses were below the knee. This contrasted with a 73 percent limb salvage rate in 104 patients whose preoperative predicted amputation level was below the knee, and a 54 percent limb salvage and a 12 percent lowering of amputation level in 39 patients whose preoperative amputation level was above the knee. Of patients with patent grafts, 89 percent achieved limb salvage. We conclude that the benefits of success in attempted vascular reconstruction for threatened limb loss far outweigh the risks of failure and that the combined results were far superior to the expected outcome in comparable patients undergoing primary amputation.

Amputation, Surgical↗
PubMed1981

Department of Surgery, Bristol Royal Infirmary, U.K.

Recent developments in ultrasound techniques have made it possible to investigate patients with arterial disease non-invasively by using Doppler blood velocity signal analysis. Since January 1979, 189 patients were pre-stroke syndromes have been investigated by using pulsed Doppler and real-time B-mode ultrasound imaging and waveform analysis. The results were that both imaging systems were highly (more than 92%) sensitive and specific when compared with conventional carotid arteriography. The ultrasound systems detected turbulence and could also be used to measure the distensibility of the arterial wall. The results show that varying grades of carotid stenosis can be demonstrated by two ultrasonic imaging systems, and that lateral scans are particularly helpful.

Blood Flow Velocity↗
PubMed1981

Carotid artery stenosis - hemodynamic significance and clinical course.

Two hundred fifteen patients with a history of either stroke, transient ischemic attack (TIA), or asymptomatic carotid bruit underwent noninvasive carotid artery testing using oculopneumoplethysmography. Of patients with hemodynamically significant stenosis, 51 (40.8%) underwent endarterectomy, and 74 (59.2%) were treated nonoperatively. The incidence of stroke in the nonoperated group was 12/74 (16.2%) compared with only 1/51 (1.9%) in the operated group. Similarly, recurrent TIA occurred in 29/74 (39.2%) of the nonoperated group vs 9/51 (17.6%) of the operated. In nonhemodynamically significant carotid stenosis, the risk of cerebrovascular death and stroke was exceedingly low: 2/90 (2.2%). Patients with hemodynamically significant stenosis treated nonoperatively have a greater risk of cerebrovascular death, stroke, and TIA than patients treated with carotid endarterectomy.

Arterial Occlusive Diseases↗
PubMed1981

Evaluation of internal carotid stenosis with the Chronopulse, an automated ocular pulse arrival time recorder.

The diagnostic value of ocular pulse time measurement with the Chronopulse was evaluated in 67 patients who had carotid arteriography. The diagnostic accuracy of 85.5 percent was comparable to that obtained by two other groups using a different timing device. Identification of bilateral stenosis was the major problem encountered and resulted from measuring the external carotid circulation at the ear. Ocular pneumoplethysmography performed in the same patients yielded a higher diagnostic accuracy than the pulse timing, and combining the two did not enhance the results. Therefore, we recommend that the Chronopulse not be used as part of the routine ocular pneumoplethysmographic examination but that it be reserved for selective application.

Blood Pressure↗
PubMed1980

Collagenase activity of the human aorta. A comparison of patients with and without abdominal aortic aneurysms.

Deficit of collagen may be a precipitating cause of aneurysm formation and expansion. Specimens of aneurysmal wall were obtained from 11 patients who underwent aneurysmectomy. Comparison aortic specimens were obtained from five patients who underwent aortofemoral bypass for occlusive disease. Collagenase activity was determined on the particulate and soluble fractions by the liberation of L-leucine, with bovine collagen as the substrate. Collagenase activity was detectable in the abdominal aortic aneurysms (AAAs) but not in atherosclerotic aorta or fascia. Collagenase activity was restricted to the particulate fraction in patients with AAAs, and it correlated with aneurysm size. These data suggest that (1) endogenous collagenolytic activity may be responsible for aneurysmal expansion and rupture and that (2) this enzyme is localized in the aneurysmal wall and is inoperative in arteries affected by atherosclerosis.

Age Factors↗