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Biomedical subjects

W H Baker

Publications and source records attributed to W H Baker.

At least 73 records · Page 4Linked to original sources
PubMed1989

Use of sequential B-mode ultrasonography to manage abdominal aortic aneurysms.

The utility and safety of sequential B-mode ultrasonography to treat male patients with small (less than 6.0 cm in diameter) abdominal aortic aneurysms (AAAs) were studied retrospectively in 149 consecutive patients. Sixty-three of these patients have had operative repair of the AAA. Eight-six remain unoperated on. Mean growth rate was 0.79 cm/y (1.06 cm/y in the operated-on group and 0.36 cm/y in the unoperated-on group). Seven patients sustained rupture of the AAA during follow-up and 4 patients died as a consequence of elective repair, for a combined mortality rate of 7.4% (11/149). Only one AAA that was less than 5.0 cm ruptured. This has proved to be an effective way to manage AAAs in this population.

Aged↗
PubMed1989

Institutionally shared trauma rotations are viable solutions to deficiencies in trauma training.

Numerous national trauma leaders have expressed concern about the lack of uniformity of trauma training in this country. In 1984 we instituted a trauma rotation between the University of Louisville (U.L.), with a large trauma volume, and Loyola University (L.U.) in the planning stages of trauma center development. Third year L.U. residents rotated at U.L. in 3-month blocks with an increased level of responsibility monthly, culminating in major decision-making roles and operative treatment under the chief resident's direction. The L.U. residents functioned as full members of the team and not as passive observers. Fifteen L.U. residents and 12 U.L. residents rotated during this period. Yearly major trauma visits, helicopter flights, and trauma service admissions average 1,908, 700, and 1,520, respectively. U.L. chief residents averaged 136 major operative trauma cases and 115 nonoperative trauma cases each were managed during this time period (RRC records greater than 85th percentile for all U.L. residents). L.U. residents performed an average of 30 major operative cases, nine as teaching assistant, in 3 months. Each managed more than 75 nonoperative cases. Several elements are critical in such a multi-institutional rotation: 1) active communication among the program directors, 2) commitment to one sharing arrangement only, 3) financing and malpractice for off-site residents, 4) housing, and 5) the ability to assimilate off-site residents as true trauma team members. The resident-to-resident interplay is crucial and has succeeded because both residency staffs have had excellent early training.(ABSTRACT TRUNCATED AT 250 WORDS)

Academic Medical Centers↗
PubMed1989

Successful revascularization of an occluded renal artery after prolonged anuria.

Renal atherosclerosis and fibromuscular dysplasia are the most common causes of curable human renovascular hypertension and renal failure. Vascular reconstruction often preserves renal function, but renal failure is rarely reversed, especially after days of anuria. We report a case of a 23-year-old woman who as a child underwent a nephrectomy for congenital hydroureter and renal hypoplasia. She later experienced fibromuscular dysplasia of the remaining renal artery, which ultimately progressed to a complete occlusion and 31 days of total anuria. The patient was revascularized, and within 2 months renal function returned with a blood urea nitrogen and creatinine of 9.0 and 1.0 mg/dl, respectively. After a follow-up of 6 months the patient's blood pressure remained 120/80 to 130/80 mm Hg without administration of hypertension medication. In this report we emphasize that under selected circumstances a kidney can survive prolonged ischemia and that delayed revascularization may reestablish renal function.

Adult↗
PubMed1988

Secondary vascular procedures with polytetrafluoroethylene grafts for lower extremity ischemia in a male veteran population.

Secondary vascular procedures to below-knee vessels for lower extremity ischemia present a challenge to the vascular surgeon. Autogenous vein is often unavailable and failure of the previous bypass often limits the choice of distal vessels suitable for revascularization. This dilemma raises the question of amputation vs secondary vascular surgery. To address this question we reviewed the results of our previous aggressive approach to revascularization in a select group of 25 patients (26 limbs) who had secondary procedures with polytetrafluoroethylene grafts to tibial vessels or the infragenicular popliteal artery with single-vessel runoff. Nine of these 26 bypasses (35%) have remained patent for a mean of 17.2 months and no amputations have been done in this group. The other 17 bypasses (65%) have occluded from 1 day to 36 months postoperatively (mean 4.3 months); 15 of these limbs have required major amputation (58%). Ten were performed within the first 3 months postoperatively. Thirteen of the 25 patients died in the follow-up period (mean 27.5 months); five of these patients had viable limbs. Of 12 surviving patients (mean follow-up 19.9 months), six had viable limbs and six have required amputation. These results indicate that patients having secondary vascular surgical procedures with polytetrafluoroethylene grafts to tibial vessels have a high amputation rate and poor overall survival. Within this select group of patients, those who could walk with the aid of a prosthesis should be considered as candidates for primary amputation. This would facilitate rehabilitation and avoid the anguish of recurrent graft failure and multiple procedures.

Adult↗
PubMed1988

Anomalous branches of the cervical internal carotid artery: two cases of clinical importance.

Anomalous branches of the cervical portion of the internal carotid artery are rare. Reports in which these anomalous branches are of any clinical importance are even more rare. We are reporting two cases in which the anomalous branch maintained patency of the cervical portion of the proximally occluded internal carotid artery. Both patients initially had hemispheric symptoms appropriate to the affected internal carotid artery. This article details angiographic methods to demonstrate the unusual anatomic and pathologic aspects of these cases and the successful operative approach.

Aged↗
PubMed1988

The effect of contralateral disease on carotid Doppler frequency.

Continuous-wave Doppler frequency analysis is one standard of noninvasive evaluation for stenotic carotid disease. Interpretation is most commonly based on frequency recorded at the site of stenosis. If flow velocity is increased because of contralateral disease, this criterion may overstate the degree of stenosis. To investigate this, three centers contributed 167 patients to a study of carotid Doppler frequency analysis. Each patient underwent bilateral carotid studies by a standard protocol with use of continuous-wave 5 MHz Doppler probe. There were 309 patent and 25 occluded internal carotids seen on subsequent angiographs. Each patient side was categorized by the severity of ipsilateral disease (less than 45%, 45% to 70%, 71% to 99%, occlusion) and then subgrouped by contralateral disease. For all carotid arteries, the optimal peak frequency to detect 45% or more stenosis was 5500 Hz, with an overall accuracy of 92.2%. Within the three classifications of ipsilateral stenosis, a trend was noted that related increasing peak frequency to greater degrees of contralateral disease. This was most apparent when the contralateral internal carotid artery was occluded. Of all false-positive errors, 43% were accounted for by this subset that represented 15% of the total population. For the 25 patients with occlusion opposite a stenosis, the 5500 Hz cutoff of Doppler peak frequency yielded only 76% accuracy; an ROC curve showed that a cutoff value of 8500 Hz improved overall accuracy to 92% for these patients. By applying two cutoff criteria--5500 Hz for those with patent contralateral internal carotids and 8500 Hz for those in whom a contralateral Doppler signal was not detected--the overall accuracy for all patients improved to 93.3%. It is concluded that contralateral occlusion affects Doppler peak frequency by increasing the velocity in the companion carotid artery, whereas severe contralateral stenosis did not result in a consistent pattern of increased velocity.

Carotid Artery Diseases↗
PubMed1988

Mechanisms of arterial and aneurysmal tortuosity.

Most arteries follow a straight course because they are stretched by longitudinal traction. However, aneurysms and arteries in aged, hypertensive patients often exhibit tortuosity. This study was undertaken to examine mechanisms of tortuosity and the role of the arterial wall connective tissues. Experiments were performed in vitro on 48 dog carotid arteries before and after treatment with elastase or collagenase. Degradation of wall elastin caused aneurysmal dilatation and a marked decrease in longitudinal retractive force (p less than 0.05). This permitted the development of tortuosity. Degradation of wall collagen caused minimal dilatation but did cause vessel rupture; however, degradation of collagen produced no decrease in longitudinal retractive force (p = NS). These data demonstrate that failure of elastin permits vessels to (1) dilate aneurysmally and (2) elongate sufficiently to become tortuous. Failure of elastin plays a role in the tortuosity seen with age and hypertension, congenital kinking of arteries, aneurysms, and ectasias (arteriomegaly). Failure of collagen causes vessels to rupture but does not facilitate the development of tortuosity.

Aneurysm↗
PubMed1987

Reproducibility of transcutaneous continuous-wave Doppler testing of the carotid arteries.

Hand-held, continuous-wave Doppler probes, coupled with sound spectral analysis, can successfully predict carotid artery stenosis. Changing either the emitting frequency of the probe, the beam/artery angle of the carotid flow velocity (e.g. cardiac output) may alter the recorded frequency shifts. These effects raise questions as to the efficacy of this technique to serially follow carotid atheroma for progressive stenosis. To test the inherent problems with this methodology, a study of reproducibility was conducted. Two Doppler probes (5 MHz and 8 MHz) were compared at the same sitting in 24 patients; 12 were restudied on two subsequent occasions. Peak systolic frequency was 135% higher with the 8 MHz probe; this was lower than the 160% calculated by substitution for emitting frequency in the Doppler formula. The linear correlation coefficient of the two probes was 0.88. In relationship to established laboratory criteria of a greater than 75% area stenosis, no errors were noted with the 5 MHz probe while four errors were noted with the 8 MHz probe. A serial study variation of peak systolic frequency was noted for both probes; these variations did not cross established criteria levels of a severe stenosis when the 5 MHz probe was used, but did with the 8 MHz probe for two carotids. A standard examining probe is recommended. Angle and cardiac output changes do result in peak systolic frequency variation from test to test, but these were not clinically significant with the 5 MHz probe. Thus, significant changes during follow-up testing should provide an index of evolving carotid stenosis.

Arterial Occlusive Diseases↗
PubMed1987

Pathologic characteristics of recurrent carotid artery stenosis.

Recurrent carotid stenosis occurs randomly in approximately 10% of patients undergoing endarterectomy. Previous studies have described several histologic features but have failed to clearly elucidate the pathogenesis of this disorder. To improve our understanding of this disease, we reviewed pathologic lesions from 20 patients with recurrent stenosis. All specimens had been fixed in formalin and were embedded in paraffin and had undergone routine microscopic studies. In addition, immunoperoxidase staining with anti-factor VIII for endothelial cells and anti-desmin and anti-actin for smooth muscle cells was performed. Recurrent stenosis had developed in 16 of the 20 specimens within 2 years of endarterectomy (early), whereas the remaining four cases occurred from 2 to 7 years after the original carotid endarterectomy (late). Endothelial cells were found lining the luminal surface of both early and late recurrent lesions. Six of sixteen early and three of four late specimens had areas of luminal surface covered with cells exhibiting immunoreactivity for anti-factor VIII. Cells showing immunoreactivity for actin or desmin and demonstrating the morphology of smooth muscle cells were found in 9 of 16 early restenotic lesions but in no late ones. Areas of endothelial cell lining of the recurrent carotid lesions in a substantial number of patients in this study represent a finding not previously described. The presence of these cells implies that a phase of the arterial healing after endarterectomy involves re-endothelialization. Contrary to previous reports, no significant role of thrombosis and/or intraplaque hemorrhage could be found to contribute to development of recurrent stenosis.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1987

Ruptured abdominal aneurysm subsequent to cystic medial necrosis: a case report.

The majority of abdominal aortic aneurysms are the result of atherosclerosis. Cystic medial necrosis is a pathologic finding classically associated with thoracic aortic dissection, particularly in patients with Marfan's syndrome. The presence of cystic medial necrosis in other segments of the aorta or its branches is unusual. We report a case of a ruptured abdominal aortic aneurysm in a 38-year-old woman without Marfan's syndrome.

Adult↗
PubMed1987

Recurrent sympathetic dystrophy: successful treatment by contralateral sympathectomy.

Reflex sympathetic dystrophy comprises a group of disorders characterized by disabling pain and vasomotor disturbances. Sympathectomy has become a mainstay of therapy. Recurrent symptoms following sympathectomy have been attributed to incorrect diagnosis, delayed treatment, or secondary gains. This report concerns a case of lower-extremity reflex sympathetic dystrophy that recurred following an initially curative sympathectomy and that responded to treatment with contralateral sympathectomy. We suggest that these recurrent symptoms may be due to reinnervation from the contralateral lumbar sympathetic chain.

Adult↗
PubMed1987

Effect of prior arterial reconstruction on the outcome of femorofemoral bypass.

To study the effect of previous arterial reconstruction at the femoral level on the outcome of femorofemoral bypass, 63 male patients who were operated upon from 1977 to 1985 were reviewed retrospectively. Thirty-four patients had no previous surgery (Group A) and 29 had had previous femoral-level surgery (Group B). Both groups were comparable for risk factors and indications for operation. Previous reconstructions included 36 inflow and 24 outflow procedures. Operatively, recipient profundaplasty was required in 79 per cent of Group B versus 32 per cent in Group A. Early results (fewer than 30 days) were comparable for mortality, graft thrombosis, and amputation. Late results showed similar graft thrombosis and cumulative patency rates. The need for reoperation (32 vs 9%) and major amputation (14.8 vs 3%) were increased in Group B but not significantly different. Primary and secondary femorofemoral bypass are both efficacious with the outcome determined by the progression of distal atherosclerosis.

Arteriosclerosis↗
PubMed1986

Anastomotic pseudoaneurysms. A continuing late complication of vascular reconstructive procedures.

Anastomotic pseudoaneurysms continue to be a late complication of vascular grafting procedures. We reviewed the records of 48 patients who presented with 65 abdominal or lower extremity anastomotic pseudoaneurysms during 1977 to 1985. The interval between the original operation and the development of a pseudoaneurysm was 6.2 years (range, 2.5 months to 19 years). Most patients underwent resection of the involved segment of graft and artery with placement of an interposition graft. Graft patency was 97.5% during a mean follow-up of 2.4 years (range, two months to five years), and one operative mortality occurred. Four patients had emergency procedures; one patient underwent reconstruction, and three others underwent resection of the pseudoaneurysms alone. Two of those patients died, and the one survivor eventually required a high amputation. We recommend aggressive diagnosis and surgical reconstruction in these patients usually by interposition grafts or anastomotic revisions because the short- and long-term results are excellent. Morbidity and mortality are greatly increased when these procedures are done emergently.

Aged↗
PubMed1986

Molecular markers of hemostatic activation in atherosclerosis: a new concept in diagnostic profiling of endogenous pathophysiologic transition.

Molecular markers of hemostatic activation provide a reliable measure of the endogenous pathophysiologic state in atherosclerosis. Measurement of these markers before and after exercise provides a diagnostic probe for cellular-vascular interactions in patients with atherosclerosis. Molecular markers may possibly identify very early stages of atherosclerosis due to their inherent sensitivity. A high-risk cardiovascular population can be easily recognized by profiling molecular markers of hemostatic activation. Newly developed immunoassays can be used to quantitate these markers in routine laboratories. Additional clinical studies are needed to establish the diagnostic role of these molecular markers in patients with atherosclerosis and related disorders.

6-Ketoprostaglandin F1 alpha↗
PubMed1986

Pneumatic compression devices for prophylaxis of deep venous thrombosis (DVT).

A pneumatic compression device was applied to 155 patients with a normal Doppler venous examination who underwent a general surgical procedure of at least 1 hr in duration. One hundred fifty-three patients had neither PE nor DVT clinically or by Doppler studies, one patient had a venographically proven DVT, and one patient had a clinical pulmonary embolism verified by lung scanning. Using clinical and Doppler criteria, the device was effective in the prophylaxis of thromboembolic complications.

Aged↗
PubMed1986

Intra-arterial digital subtraction angiography as a method to study peripheral vascular disease.

In many patients with peripheral vascular disease, conventional arteriograms are not adequate to make proper preoperative decisions. In the past, these inadequate studies led to surgical exploration of vessels and intraoperative angiography to determine operability. Such efforts prolonged operating time and potentially had adverse effects on amputation levels. Recently, intra-arterial digital subtraction angiography (IDSA) has provided an excellent means to further evaluate these patients preoperatively. We presently have 30 patients in whom IDSA supplemented routine aortography and runoff studies. When standard angiographic studies were considered inadequate, the catheter was positioned appropriately and IDSA was obtained. Inadequate lower extremity distal runoff in 23 patients and no proximal or distal runoff in seven patients prompted the IDSA. The IDSA study yielded further information on all patients, and 26 of 30 patients underwent successful bypass operation. In all 17 patients having femoropopliteal or femorotibial bypass, the IDSA was confirmed by an intraoperative (after bypass) angiogram. Nine patients had inflow procedures, and operative findings corroborated the IDSA. Two patients refused surgery and two patients were not candidates for revascularization. The IDSA study provided an accurate "road map," eliminated unnecessary vessel exploration, saved vital operative time, and prevented compromise of potential amputation levels.

Aged↗