Biomedical subjects

M T Caps

Publications and source records attributed to M T Caps.

26 records · Page 2Linked to original sources

PubMed1996

A clinical marker for arterial wall healing: the double line.

PURPOSE: B-mode imaging of a normal arterial wall shows two echo-dense lines separated by an echolucent zone. Immediately after carotid endarterectomy, this double-line pattern is no longer detectable, but it subsequently reappears in some patients. The objective of this study was to test the hypothesis that the postoperative double line is associated with a lower incidence of carotid restenosis. METHODS: Carotid arteries were serially studied with B-mode ultrasound imaging at 2 weeks and 1, 2, 3, 6, 9, 12, 18, and 24 months after carotid endarterectomy. The wall of the common carotid artery 1 to 2 cm distal to the proximal endarterectomized shelf was analyzed for the presence, quality, and thickness of double lines. All hemodynamically significant stenoses (> or = 50% diameter reducing) were documented with standard duplex scanning criteria. RESULTS: Twenty-four carotid arteries in 23 patients were studied for a mean of 14.7 months (range, 3 to 24 months). A double line developed in 21 common carotid arteries (87.5%) at a mean time of 3.2 months (range, 0.5 to 9.0 months) after surgery with a mean thickness of 0.65 mm (SD = 0.17 mm) at the time of initial detection. A single hemodynamically significant stenosis developed in this group. All three of the remaining arteries that did not form the double-line pattern developed hemodynamically significant stenoses. Carotid restenosis was more likely to occur in arteries that did not form double lines (p < 0.05, Fisher's exact test). CONCLUSIONS: The majority of carotid arteries re-form a double line after endarterectomy. These arteries are less likely to develop restenotic lesions caused by myointimal hyperplasia.

Aged↗

PubMed1995

Vein graft lesions: time of onset and rate of progression.

PURPOSE: The objectives of this study were to determine the time of onset, location, severity, rate of progression, and subsequent fate of infrainguinal vein graft lesions. METHODS: Sixty-one infrainguinal vein grafts were studied serially with duplex ultrasonography to document the location and severity of each lesion. Grafts were studied at 1, 2, 3, 4, 6, 9, 12, and 18 months and then annually. RESULTS: The cumulative secondary graft patency rate at 3 years (life-table analysis) was 93.2%. A total of 158 lesions were detected in 55 of the 61 grafts studied. The degree of diameter reduction at the time of initial detection was as follows: 1% to 19% (29.6%), 20% to 49% (51.0%), 50% to 75% (17.3%), and greater than 75% (3.1%). Forty-eight percent were detected at the first examination, 59.2% within 2 months, and 85.7% within 6 months. Progression was detected in 31.2% of the lesions by 6 and in 39.1% of the lesions by 18 months (life-table analysis). Thrombosis, in the absence of significant changes in ankle-brachial index (> or = 0.15) or return of symptoms, was not observed in grafts that had lesions with less than 75% diameter reduction. CONCLUSIONS: The data support the performance of a duplex scan either during surgery or before discharge from the hospital in addition to frequent surveillance for the first 6 months. Frequent surveillance is appropriate for lesions with less than 75% diameter reduction as long as they remain asymptomatic and without a significant reduction in the ankle-brachial index.

Disease Progression↗

PubMed1995

Venous valvular reflux in veins not involved at the time of acute deep vein thrombosis.

PURPOSE: The aim of this study was to determine whether, in lower extremities with documented episodes of acute deep venous thrombosis (DVT), incompetence develops in veins that were not the site of thrombosis. METHODS: Patients were monitored with serial duplex ultrasonography at 1 day, 1 week, 1, 3, 6, 9, and 12 months, and then annually after detection of acute DVT. The following venous segments were analyzed: common femoral, greater saphenous, proximal superficial femoral, deep femoral, popliteal, and posterior tibial. The incidence of reflux development in both thrombosed and uninvolved segments was determined. Reflux was categorized as either transient or permanent. RESULTS: A total of 227 limbs in 188 patients were serially studied. Mean follow-up was 19.9 months (range 1 to 88 months). Overall, 403 of the 1423 segments (28.3% +/- 2.3%) developed reflux during the study, of which 118 (29.3% +/- 4.4%) had no prior or concurrent history of thrombosis. Considering only the segments that developed incompetence, the percent without prior thrombosis at each level was as follows: common femoral vein (40.0%), greater saphenous vein (53.1%), deep femoral vein (20.6%), proximal superficial femoral vein (23.9%), popliteal vein (8.9%), and posterior tibial vein (31.9%). Valvular insufficiency developing in segments uninvolved with thrombus was more likely to be transient (40.2%) than was the reflux in thrombosed segments (22.6%). This difference was statistically significant (p < 0.05). CONCLUSIONS: Permanent venous valvular damage can occur in the absence of thrombosis after DVT. Reflux in uninvolved venous segments has a different anatomic distribution and is more likely to be transient than the incompetence associated with thrombosis.

Acute Disease↗

PubMed1995

Propagation, rethrombosis and new thrombus formation after acute deep venous thrombosis.

PURPOSE: The purpose of this study was to determine the incidence, timing, and outcome of further thrombotic events after an initial episode of acute deep venous thrombosis. METHODS: Venous thrombi in 204 lower extremities (177 patients) were monitored with duplex ultrasonography at intervals of 1 day, 7 days, 1 month, every 3 months for 1 year, and yearly thereafter. RESULTS: Among initially involved extremities, propagation to new segments occurred in 61 (30%) and rethrombosis occurred in 63 (31%). Both propagation and rethrombosis, in different segments, occurred in 27 (13%) extremities. New thrombi were also noted in nine (6%) initially uninvolved extremities. These events were not associated with identifiable clinical risk factors, although extremities with rethrombosis were more extensively involved at presentation. Propagation in initially involved extremities was an early event, occurring within a median of 40 days in all segments. New thrombotic events in initially uninvolved extremities and rethrombosis occurred as later events. The development of reflux was significantly more common among all initially uninvolved segments to which thrombus extended and among mid and distal superficial femoral and popliteal artery segments with rethrombosis. CONCLUSIONS: Recurrent thrombotic events are common after acute deep venous thrombosis and adversely affect the ultimate development of valvular incompetence. Their occurrence is unrelated to recognized clinical risk factors and can occur despite standard anticoagulation measures.

Acute Disease↗

PubMedDate not supplied

Prospective study of atherosclerotic disease progression in the renal artery.

BACKGROUND: The aim of this study was to determine the incidence of and the risk factors associated with progression of renal artery disease in individuals with atherosclerotic renal artery stenosis (ARAS). METHODS AND RESULTS: Subjects with >/=1 ARAS were monitored with serial renal artery duplex scans. A total of 295 kidneys in 170 patients were monitored for a mean of 33 months. Overall, the cumulative incidence of ARAS progression was 35% at 3 years and 51% at 5 years. The 3-year cumulative incidence of renal artery disease progression stratified by baseline disease classification was 18%, 28%, and 49% for renal arteries initially classified as normal, <60% stenosis, and >/=60% stenosis, respectively (P=0.03, log-rank test). There were only 9 renal artery occlusions during the study, all of which occurred in renal arteries having >/=60% stenosis at the examination before the detection of occlusion. A stepwise Cox proportional hazards model included 4 baseline factors that were significantly associated with the risk of renal artery disease progression during follow-up: systolic blood pressure >/=160 mm Hg (relative risk [RR]=2.1; 95% CI, 1.2 to 3.5), diabetes mellitus (RR=2.0; 95% CI, 1.2 to 3.3), and high-grade (>60% stenosis or occlusion) disease in either the ipsilateral (RR=1.9; 95% CI, 1.2 to 3.0) or contralateral (RR=1.7; 95% CI, 1.0 to 2.8) renal artery. CONCLUSIONS: Although renal artery disease progression is a frequent occurrence, progression to total renal artery occlusion is not. The risk of renal artery disease progression is highest among individuals with preexisting high-grade stenosis in either renal artery, elevated systolic blood pressure, and diabetes mellitus.

Aged↗

PubMedDate not supplied

Trends in lower limb amputation in the Veterans Health Administration, 1989-1998.

OBJECTIVE: To assess trends in lower limb amputation performed in Veterans Health Administration (VHA) facilities. METHODS: All lower limb amputations recorded in the Patient Treatment File for 1989-1998 were analyzed using the hospital discharge as the unit of analysis. Age-specific rates were calculated using the VHA user-population as the denominator. Frequency tables and linear, logistic, and Poisson regression were used respectively to assess trends in amputation numbers, reoperation rates, and age-specific amputation rates. RESULTS: Between 1989-1998, there were 60,324 discharges with amputation in VHA facilities. Over 99.9% of these were in men and constitute 10 percent of all US male amputations. The major indications were diabetes (62.9%) and peripheral vascular disease alone (23.6%). The age-specific rates of major amputation in the VHA are higher than US rates of major amputation. VHA rates of major and minor amputation declined an average of 5% each year, while the number of diabetes-associated amputations remained the same. CONCLUSION: The number and age-specific rates of amputations decreased over 10 years despite an increase in the number of veterans using VHA care.

Adult↗

PubMedDate not supplied

Survival following lower-limb amputation in a veteran population.

GOAL: We sought to describe the common demographic and comorbid conditions that affect survival following nontraumatic amputation. METHODS: Veterans Administration hospital discharge records for 1992 were linked with death records. The most proximal level during the first hospitalization in 1992 was used for analysis. Demographic information (age, race) and comorbid diagnosis (cardiovascular, cerebrovascular, and renal disease) were used for Kaplan-Meier curves to describe survival following amputation. MAIN OUTCOME MEASURE: Death. RESULTS: Mortality risk increased with advanced age, more proximal amputation level, and renal and cardiovascular disease, and decreased for African Americans. No increased risk for persons with diabetes was noted in the first year following amputation but the risk increased thereafter. A higher risk of mortality in the first year was noted for renal disease, cardiovascular disease, and proximal amputation level. CONCLUSION: Survival following lower-limb amputation is impaired by advancing age, cardiovascular and renal disease, and proximal amputation level. Also, a small survival advantage is seen for African Americans and those with diabetes.

Adult↗

PubMedDate not supplied

Trends in peripheral vascular procedures in the Veterans Health Administration, 1989-1998.

OBJECTIVE: To assess trends in peripheral vascular procedures performed in Veterans Health Administration (VHA) facilities. METHODS: All discharges with peripheral vascular procedures recorded for 1989-1998 were analyzed. The VHA user population was used to calculate age-specific rates. Trends were evaluated using frequency tables and Poisson regression. RESULTS: The VHA had 55,916 discharges with peripheral vascular procedures performed almost exclusively in men. Indications included peripheral vascular disease (53.7%), gangrene (19.3%), surgical complications (13.3%), and ulcers and infection (9.6%). The VHA age-specific rates were higher than US population rates for persons 45 to 64 years, similar for those 65 to 74 years, and lower for those 75 years and older. The age-specific rates declined slightly over the 10 years of observation, with the greatest decline noted in men age 45 to 65. CONCLUSION: The VHA provides almost 8% of all US peripheral vascular procedures in males. The VHA age-specific rates differ from the US rates with a shift to younger patients. The rates decreased for all age groups between 1989-1998.

Aged↗