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Biomedical subjects

G Ramaswami

Publications and source records attributed to G Ramaswami.

At least 19 recordsLinked to original sources
PubMed2001

Correlates of embolic events detected by means of transcranial Doppler in patients with carotid atheroma.

PURPOSE: This study identified in patients with carotid plaques the associations of emboli detected by means of transcranial Doppler (TCD) with cerebrovascular symptoms, brain computed tomography (CT) infarction patterns, and the attributes of plaques (echodensity, degree of stenosis). METHODS: Eighty carotid plaques (in 59 patients), producing 50% to 99% stenosis, were imaged on duplex scanning and analyzed echomorphologically in a computer with the gray scale median (GSM). The GSM facilitated the quantitative distinction of dark (low GSM) from bright (high GSM) plaques. Stenosis was assessed with duplex scanning. Emboli were counted on TCD in the ipsilateral middle cerebral artery for half an hour. The brain CT infarction patterns (pattern A: discrete subcortical and cortical; pattern B: hemodynamic, diffuse white matter lesions, basal ganglia infarctions, lacunes) and normal CT and cerebrovascular symptoms on the ipsilateral hemisphere were noted. RESULTS: Emboli were more frequent in symptomatic (median count, 3) than asymptomatic (median count, 0) hemispheres (Mann-Whitney U test, P =.031) and in hemispheres with pattern A infarction (median count, 3.5) than in hemispheres with pattern B infarction or normal CT (median count, 0; Kruskal-Wallis test, P =.047). The increased embolic count was associated with decreased GSM (Spearman correlation, P =.045, r = -0.22), but not with high degrees of stenosis (Spearman correlation, P =.44, r = 0.086). CONCLUSION: Emboli were more frequent in symptomatic than asymptomatic hemispheres and in CT pattern A harboring hemispheres than in CT pattern B or normal hemispheres. They were more frequent in the presence of low-plaque echodensity, but not in the presence of a high degree of stenosis. These data support the embolic nature of cerebrovascular symptomatology and CT pattern A infarctions.

Aged↗
PubMed2001

Endovascular stent grafting in the presence of aortic neck filling defects: early clinical experience.

OBJECTIVE: Although endovascular grafts have been increasingly applied to the treatment of abdominal aortic aneurysms, their use in clinical trials is limited by well-defined anatomical exclusion criteria. One such criterion is the presence of thrombus within the infrarenal neck of an aneurysm, which is thought to (1) prevent the creation of a permanent watertight seal between the graft and the vessel wall, resulting in an endoleak; (2) contribute to stent migration; and (3) increase the risk of thromboembolism. This article summarizes our experience with endovascular abdominal aortic aneurysm exclusion in 19 patients with large aortic aneurysms, significant medical comorbidities, and apparent thrombus extending into the pararenal aortic neck. METHODS: Of 268 patients undergoing abdominal aortic aneurysm repair, 19 (7%; 17 men; mean age, 71 years) demonstrated computed tomographic and angiographic evidence of intramural filling defects at the level of the aortic neck. In no instance did these filling defects extend above the renal arteries. Endovascular grafting was performed through use of a balloon-expandable Palmaz stent and an expanded polytetrafluoroethylene graft, delivered and deployed under fluoroscopic guidance. Follow-up at 3, 6, and 12 months and annually thereafter was performed with computed tomography and duplex ultrasound scan. RESULTS: Spiral computed tomography and aortography revealed an irregular flow-limiting defect, occupying up to 75% of the aortic circumference, in every case. The mean aneurysm size, aortic neck diameter, and neck length before the procedure were 6.1, 2.43, and 1.4 cm, respectively; the mean aortic neck diameter after the procedure was 2.61 cm. No primary endoleaks were observed after graft insertion, and no delayed endoleaks have been detected during follow-up, which ranged from 7 to 48 months (mean, 23 months). In one patient, an asymptomatic renal artery embolus was detected on immediate follow-up computed tomography, and in another patient, an asymptomatic posterior tibial embolus occurred. CONCLUSION: No primary endoleaks, endograft migration, or significant distal embolization were observed after endografting in patients with aortic neck thrombus. The deployment of the fenestrated portion of the stent, above the thrombus and across the renal arteries, allows for effective renal perfusion, graft fixation, and exclusion of potential mural thrombus from the circulation. The presence of aortic neck thrombus may not necessarily be a contraindication to endovascular repair in select patients.

Aged↗
PubMed2000

PGE(1) treatment of severe intermittent claudication (short-term versus long-term, associated with exercise)--efficacy and costs in a 20-week, randomized trial.

The efficacy, safety, and cost of prostaglandin E1 (PGE1) in the treatment of severe intermittent claudication was studied comparing a long-term treatment protocol (LTP) with a short-term treatment protocol (STP) in a randomized 20-week study. The study included 980 patients (883 completed the study) with an average total walking distance of 85.5 +/-10 m (range 22-119). Phase 1 was a 2-week run-in phase (no treatment) for both protocols. In LTP, phase 2 was the main treatment phase. In the LTP, treatment was performed with 2-hour infusions (60 microg PGE1, 5 days each week for 4 weeks. In phase 3 (4-week interval period) PGE1 was administered twice a week (same dosage). In phase 4 (monitoring lasting 3 months, from week 9 to 20) no drugs were used. In STP phase 2 treatment was performed in 2 days by a 2-hour infusion (first day: morning 20 microg, afternoon 40 microg; second day morning and afternoon 60 microg). The reduced dosage was used only at the first cycle (week 0) to evaluate tolerability or side effects. Full dosage (60 microg bid) was used for all other cycles. The same cycle was repeated at the beginning of weeks 4, 8, and 12. The observation period was between weeks 12 and 20. A treadmill test was performed at inclusion, at the beginning of each phase, and at the end of 20th week. A similar progressive physical training plan (based on walking) and a reduction in risk factors levels plan was used in both groups. Intention-to-treat analysis indicated an increase in walking distance, which improved at 4 weeks and at 20 weeks in the STP more than in the LTP group. At 4 weeks the variation (increase) in pain-free walking (PFWD) was 167.8% (of the initial value) in the LTP group and 185% in the STP group (p<0.05). At 4 weeks the variation (increase) in total walking distance (TWD) was 227.6% of the initial value in the LTP group and 289% in the STP group (p<0.05). At 20 weeks the increase in PFWD was 496% of the initial value in the LTP group vs 643% in the STP group (147% difference; p<0.02). The increase in TWD was 368% in the LTP group and 529% in the STP group (161% difference; p<0.02). In both groups there was a significant increase in PFWD and TWD at 4 and 20 weeks, but results obtained with STP are better considering both walking distances. No serious drug-related side effects were observed. Local, mild adverse reactions were seen in 6.3% of the treated subjects in the LTP and 3% in the STP. Average cost of LTP was 6,664 Euro; for STP the average costs was approximately 1,820 E. The cost to achieve an improvement in walking distance of 1 m was 45.8 E with the LTP and 8.5 E with the STP (18% of the LTP cost; p<0.02). For an average 100% increase in walking distance the LTP cost was 1,989 E vs. 421 E with STP (p<0.02). Between-group analysis favors STP considering walking distance and costs. Results indicate good efficacy and tolerability of PGE, treatment. With STP less time is spent in infusion and more in the exercise program. STP reduces costs, speeds rehabilitation, and may be easily used in a larger number of nonspecialized units.

Aged↗
PubMed1999

The role of duplex scanning in the diagnosis of lower limb arterial disease.

Color flow duplex imaging of the iliac and femoropopliteal arteries was performed in patients undergoing angiography. The aim of the study was to determine: (1) in what percentage of patients could the iliac arteries be adequately visualized to enable a diagnosis, (2) the overall accuracy of duplex scanning in the diagnosis of arterial disease, and (3) whether there is a useful duplex criterion for the selection of patients for angioplasty. One hundred and twenty patients (79 males, 41 females; mean age 64.4 years) had duplex scans prior to angiography (2-7 days) and the results were compared. The duplex criteria of an increase in the peak systolic velocity ratio (PSVR) >2 and lesions <5 cm were used to signify hemodynamically significant stenosis (>50% narrowing), the presence of plaque and calcification in the arterial wall with alteration of PSVR and lesions >5 cm, diffuse disease, and the absence of flow on color/Doppler interrogation, occlusion. The results show that duplex scanning is a useful screening tool and may be effectively used to diagnose iliac and femoropopliteal disease in nearly 80% of patients. Angiography will be needed in those in whom duplex scanning is inconclusive, or, prior to intervention in those with disease suitable for surgical reconstruction or angioplasty, diagnosed on the basis of duplex scans.

Angiography↗
PubMed1999

The role of duplex scanning in decision making for patients with claudication.

The aim of this study was to compare the accuracy of clinical decisions made for patients presenting with claudication on the basis of the ankle/brachial index (ABI) (at rest and postexercise) and duplex scanning with that made on the basis of angiograms. Fifty-six patients presenting with a history suggestive of claudication had the ABI taken at rest. Seven patients could not be exercised but their resting ABI was <0.8. Additional exercise testing was done in 49 patients; two were then excluded as there was no fall in the ABI. Thus, 54 patients were entered into the study and underwent color-flow duplex scans and angiography. A clinical decision was reached independently on the basis of the results of ABI and duplex scans as to a) conservative treatment, b) angioplasty, and c) surgery. This was compared to the decision reached on the basis of angiograms. The results show that the combined use of ABI (as a screening test) and duplex scanning can replace angiography for clinical decision making in nearly 80% of claudicants. Angiography will only be needed when duplex scans are inconclusive.

Adult↗
PubMed1999

Stent grafts in occlusive arterial disease.

The use of endovascular grafts for the treatment of occlusive arterial disease continues to evolve as the sophistication of currently available devices improves with regard to device composition and delivery systems. Endovascular grafting for occlusive arterial disease is particularly useful in high-risk patients with medical comorbidities who are otherwise unfit for a major operation and conventional open repair. The early term and midterm results on the treatment of occlusive, iliac, and femoropopliteal disease have been encouraging. Further refinements in catheter technology, stent grafts, and delivery systems will further extend the use of these devices. Increasing experience from centers using different devices and long-term follow-up with regard to durability and complication will establish the role of endovascular grafts as alternatives to conventional repair.

Aorta↗
PubMed1999

Ultrasonic plaque character and outcome after lower limb angioplasty.

PURPOSE: The value of ultrasonic plaque characteristics in identifying patients at "high-risk" of restenosis after percutaneous transluminal angioplasty (PTA) was studied. METHODS: Thirty-one arterial stenoses (6 common iliac, 2 external iliac, 1 profunda femoris, 21 superficial femoral, and 1 popliteal) in 17 patients who underwent angioplasty were studied by means of duplex scanning. With a computer-based program, B-mode images were digitized and normalized using 2 reference points, blood and adventitia. A grey level of 0 to 5 was allocated for the lumen (blood) and 180 to 190 for the adventitia on a linear gray scale of 0 to 255 (0 = absolutely black; 255 = absolutely white), and the overall plaque gray-scale median (GSM) of the pixels of the plaque was used as a measure of plaque echodensity. After PTA, follow-up of stenoses was done on day 1, weekly for 8 weeks, at 3 months, 6 months, and 1 year. The total plaque thickness (sum of anterior and posterior components), minimal luminal diameter (MLD), and peak systolic velocity ratio (PSVR) were measured for all stenoses. An increase of more than 2 in the PSVR was the duplex criterion used to signify restenosis. RESULTS: The GSM of the stenoses before angioplasty ranged from 6 to 71 (mean, 31.3 +/- 17.9); 17 stenoses had a GSM less than 25 (mean, 18.7 +/- 5.3), and 14 had a GSM more than 25 (mean, 46.4 +/- 15.8). When the GSM was less than 25, the absolute reduction in plaque thickness on day 1 post-PTA was 3.3 +/- 1.8 mm, in contrast to 1.8 +/- 1.6 mm when GSM was more than 25 (P <.03). The restenosis rate (PSVR more than 2) was 41% at 6 months and remained unchanged at 1 year. When the GSM was less than 25, restenosis occurred in 11% of lesions, in comparison with 78% when the GSM was more than 25 (P <.001). CONCLUSION: Plaque echodensity can be used to evaluate stenoses before PTA, to predict initial success and identify a subgroup that has a high prevalence of restenosis. The identification of a group at "high-risk" of restenosis can improve the selection of patients for the procedure and also be used in prospective studies on the prevention of restenosis.

Angioplasty, Balloon↗
PubMed1999

Angioplasty of lower limb arterial stenoses under ultrasound guidance: single-center experience.

PURPOSE: To examine the feasibility and utility of ultrasound-guided angioplasty for treating lower limb stenoses. METHODS: Duplex ultrasonography was employed to guide 55 balloon dilation procedures (27 iliac, 26 superficial femoral, 1 profunda, and 1 vein graft) with the help of a special ultrasound catheter (EchoMark). Ultrasound was used to determine balloon size, monitor guidewire passage, direct the dilation, and judge procedural success. Angiography was performed prior to the procedure to confirm preprocedural ultrasound findings and afterward to compare with duplex visual and hemodynamic parameters of success (peak systolic velocity ratio < 2.0). RESULTS: The balloon size determined from duplex measurements correlated in all cases with sizes selected based on the angiographic image. Guidewire visualization was possible in 95% of the cases. Angioplasty using ultrasound alone was feasible in 84%; inability to obtain a satisfactory image owing to vessel tortuosity, calcification, and bowel gas accounted for the failures. Against the duplex success criterion, initial completion angiograms had an accuracy of 76%, sensitivity of 76%, and specificity of 100%. The additional time for ultrasound guidance averaged 42 +/- 12 minutes for all cases. CONCLUSIONS: Our results show that ultrasound guidance is feasible in routine clinical practice. In this series of well-selected cases of arterial stenoses, angioplasty was performed safely using ultrasound guidance alone in over 80% of the cases. Fluoroscopic monitoring is needed when ultrasound visualization is suboptimal.

Aged↗
PubMed1998

Peter B. Samuels Award. Restenosis after percutaneous transluminal angioplasty.

BACKGROUND: Determine the feasibility of studying the natural history of the atherosclerotic plaque following percutaneous transluminal angioplasty (PTA), using duplex scanning. METHODS: Twenty-three patients with 40 stenoses (>70% and <5 cm in length) in the iliac and femoro-popliteal segments were studied by duplex scanning before PTA, on day 1, weekly for 8 weeks, and at 3 months, 6 months, and 1 year. The following measurements were made: thickness of the plaque, minimal lumen diameter (MLD), and peak systolic velocity ratio (PSVR). A PSVR >2.0 was used to indicate >50% lumen diameter reduction. RESULTS: Thirty stenoses were available for measurement and analysis. Mean reduction in plaque thickness after angioplasty was greater in echolucent plaques (2.33 +/- 0.9 mm) than echogenic plaques (0.83 +/- 0.6 mm; P < 0.0001). Successful angioplasty (PSVR <2.0) and increase in MLD in echolucent plaques was the result of plaque compression; in echogenic plaques, of wall dilatation. The incidence of restenosis (PSVR >2.0) at 6 months was 12 of 30 (40%) remaining unchanged at 1 year; of the lesions that restenosed, 33% recurred before week 8 and the remainder between weeks 8 and 24, suggesting different mechanisms. During follow-up, all plaques showed "growth"; <2 mm in 17 (57%; group A) and >2 mm in the remaining 13 (43%; group B). The incidence of restenosis (PSVR >2.0) was 4 of 17 (23%) in group A and 8 of 13 (61%) in group B (P <0.05). CONCLUSION: Duplex scanning provides valuable information on both luminal diameter and plaque thickness; it may be used to study the natural history of plaques following angioplasty and also the effects of therapeutic agents aimed at reducing restenosis.

Angioplasty, Balloon↗
PubMed1998

Shock waves in vascular diseases: an in-vitro study.

UNLABELLED: Three human aortic specimens were used for this in-vitro study on the effects of shock waves on the arterial wall. Specimen one was from a normal (for age) healthy aorta. The full abdominal length was used (including mesenteric and renal arteries and the aortoiliac bifurcation), divided into six pieces (3 cm). The pieces were placed and fixed into degassed water. Shock waves (SW) were focused onto the aortic wall by means of a B-mode ultrasound imager. An SW generator (Minilith SL1, Storz Medical AG, Kreuzlingen, Switzerland) was used for setting of energy flux density between 0.03 and 0.5 mJ/mm2. The six aortic pieces (excluding piece 1, placed in water and left untreated as control) were treated with SW at increasing energy levels. A second aortic specimen of a man with arteriosclerotic plaques was also used and the experiment repeated at energy levels 1, 5, and 8. Another specimen of normal thoracic aorta was exposed at energy levels 1 and 8 only. Energy levels delivered onto the aortic walls were selected from theoretically destructive levels to minimal levels known not to alter vascular tissues. High-resolution ultrasounds of the aortic segments were performed with a 10 MHz high-resolution, broad-band (ATL 3000, USA) probe in water before and after SW application to detect structural changes in the wall after SW. Histology was performed with a standard hematoxylin-eosin staining. RESULTS: The aortic pieces did not show macroscopic damages at visual examination, and at the ultrasound examination no visible changes were observed even at higher levels of SW energy. Also no effects were seen by histology. In conclusion, no damaging effects were observed, visually, by ultrasound, or by histology. At these energy levels SW appear to be safe and do not produce any damage to the aortic wall. Therefore, SW could be considered a safe, nondamaging procedure for potential treatment (ie, thrombolysis) in which vessel walls could be involved. Theoretically it is possible that functional changes could be observed in vivo including cell permeability modifications and other alterations (including changes in the potential of the cells in SW fields to modify themselves and to divide). At the energy levels described in this study SW could, theoretically be, safely used for vascular applications (ie, treating venous and arterial thrombi or in arterial plaques modification) without altering major, structural, arterial wall characteristics. Lesions or alterations that have a different density from the normal wall (thrombi or plaques) could be differently sensitive to the same dosage of SW. These differences in acoustic impedance characteristics could be used for potential treatments with SW without damaging the arterial wall.

Aorta↗
PubMed1998

Treatment of severe intermittent claudication with PGE1--a short-term vs a long-term infusion plan--a 20 week, European randomized trial--analysis of efficacy and costs.

The efficacy, safety, and cost of prostaglandin E1 (PGE1) in the treatment of severe intermittent claudication was studied by comparing a long-term treatment protocol (LTP) with a short-term treatment protocol (STP) in a randomized 20-week study. The study included 109 patients (96 completed the study) with an average total walking distance of 65.5 +/- 8 m (range 20-109). Phase 1 was a 2-week run-in phase (no treatment) for both protocols. In LTP, phase 2 was the main treatment phase. In the LTP, treatment was performed with 2-hour infusions (60 microg PGE1, 5 days each week for 4 weeks). In phase 3 (4-week interval period) PGE1 was administered twice a week (same dosage). In phase 4 (monitoring lasting 3 months, from week 9 to 20) no drugs were used. In STP, phase 2 treatment was performed in 2 days by a 2-hour infusion (1st day: morning 20 microg, afternoon 40 microg; 2nd day morning and afternoon 60 microg). The reduced dosage was used only at the first cycle (week 0) to evaluate reduced tolerability or side effects. Full dosage (60 microg b.i.d.) was used for all other cycles. The same cycle was repeated at the beginning of weeks 4, 8, and 12. The observation period was between weeks 12 and 20. A treadmill test was performed at inclusion, at the beginning of each phase, and at the end of the 20th week. A similar progressive physical training plan (based on walking) and a reduction in risk factors levels plan was used in both groups. Intention-to-treat analysis indicated an increase in walking distance, which improved at 4 weeks (101.5% in STP vs 78.3% in LTP), at 8 weeks (260.9% STP vs 107.3% LTP), and at 20 weeks (351% STP vs 242% LTP). Comparable increases in pain-free walking distance were observed in the two groups. No serious drug-related side effects were observed. Local, mild adverse reactions were seen in 7% of the treated subjects in the LTP and 5% in the STP. Average cost of LTP was approximately 6,588 ECU; for STP the average cost was approximately 1,881 ECU. The cost to achieve an improvement in walking distance of 1 m was 35.6 ECU with the LTP and 9.45 ECU with the STP (26% of the LTP cost; p<0.02). For an average 100% increase in walking distance the LTP cost was 1,937 ECU vs 550 ECU with STP (p<0.02). The cost of PGE1 (including infusion and operative costs) was 25% of the total cost for LTP (24.9% for STP). In summary, between-group-analysis favors STP, in terms of walking distance and costs. Results indicate good efficacy and tolerability of PGE1 treatment. With STP less time is spent in infusion and more can be spent in the exercise program. STP reduces costs, speeds up rehabilitation, and may be used in a larger number of nonspecialized units available to follow the protocol.

Alprostadil↗
PubMed1998

Ultrasonic image analysis of the arterial wall in atherosclerosis.

BACKGROUND: Atherosclerotic carotid artery plaques can be classified on the basis of their ultrasound appearance according to the pattern of echolucency and echogenicity. The most commonly used classification is the one described by Gray-Weale who defined 4 plaque types. METHODS: The images of the carotid and femoral arteries of 9 healthy volunteers and 21 non-insulin dependent diabetic patients were analysed. In this study 16 atherosclerotic carotid artery plaques were imaged by B-mode high resolution ultrasonography and then subjected to analysis of the digitised images. RESULTS: The results show that the plaques could be separated into 3 groups according to their echogenic properties. Gray-Weale plaques types 2 and 3 could not be distinguished and it is proposed that these should be classified as a single group. CONCLUSIONS: An increased echogenicity in the intima-media complex of non-insulin dependent diabetics as well as a relationship with risk factors for the development of cardiovascular disease and with the ultrasound score could not be determined in this study.

Adult↗
PubMed1997

Circadian pattern of post-surgical fatal pulmonary embolism.

BACKGROUND: The circadian distribution of fatal pulmonary thromboembolism in general surgical patients is unknown. PATIENTS AND METHODS: One hundred consecutive cases of pulmonary embolism, with reliable clinical notes and data, were studied (67 men and 33 women; mean age 71 years). Only post-surgical cases were considered in this analysis. Patients had undergone elective (78%) or emergency abdominal surgery (22%). Correct prophylaxis (according to the Windsor Consensus Statement) had been used in 12%. Cases were grouped according to the time of onset of signs and symptoms related to pulmonary embolism at one hour intervals. RESULTS: The maximum incidence of fatal pulmonary embolism was between 7.00 a. m. and 1.00 p. m. with the highest peaks at 9.00 and 11.00 a. m. 9% of deaths) (P < 0.02). When results from this study were compared to a previous study no significant difference was observed between the distribution profile of cases from general medical wards and surgical wards. CONCLUSION: It appears that in surgical patients there is a circadian pattern in pulmonary embolism as already documented in medical patients.

Aged↗
PubMed1996

The role of the distribution and anatomic extent of reflux in the development of signs and symptoms in chronic venous insufficiency.

PURPOSE: The purpose of this study was to identify the distribution of venous reflux in patients with different patterns of reflux with each class. METHODS: Color-flow duplex imaging was used to evaluate the entire venous system from groin to ankle in 465 patients (594 limbs) belonging to different clinical CVI classes (0, 1, 2, and 3). A history of previous superficial thrombophlebitis was present in five limbs and past deep vein thrombosis in 70. RESULTS: One hundred seventy eight (30%) limbs were normal and the remaining 416 (70%) had venous incompetence. Deep reflux was present exclusively in 19 limbs (3.2%), and the perforation system alone was involved in only three limbs (0.5%). However, isolated superficial incompetence was seen in 186 limbs (31.3%) and a combination of superficial with perforating alone was involved in 45 (7.6%). Incompetence in all three systems was seen in 99 extremities (16.7%). In addition, the superficial system was involved in 390 limbs, the perforators in 151, and the deep system in 178 limbs. Only a small percentage of those in class 0 had reflux, and most of them had a single site of incompetence. In class 1 the majority of the limbs had superficial reflux (90.3%), 10.3% of the limbs had deep venous reflux, and 6.9% were competent. Reflux in the superficial system was only seen in 80.7% of the limbs in class 1 and in one fifth of the limbs in classes 2 and 3. Isolated deep or perforated incompetence was rare in all classes. Variable combined patterns of reflux were seen more often in classes 2 and 3 (p < 0.0001). In classes 2 and 3 there were no differences in the number of incompetent sites in the superficial and deep venous systems or the patterns of reflux (p > 0.1). The number of incompetent perforators in class 3 tended to be higher than that in class 2, especially in the below-knee segment, but no significant differences were seen. Distal reflux was present in the majority of the limbs in all symptomatic classes (1, 2, and 3). CONCLUSIONS: The distribution and extent of reflux is strongly associated with clinical severity of CVI through class 2. Distal venous reflux is present in at least 80% of the symptomatic limbs. Deep venous thrombosis may not be a prerequisite for the development of skin changes or ulceration in about 75% of the limbs. Superficial venous surgery could be beneficial to at least one third of patients with skin changes or ulceration.

Adult↗
PubMed1996

Changes in energy metabolism of calf muscle in patients with intermittent claudication assessed by 31P magnetic resonance spectroscopy: a phase II open study.

Energy status and metabolism in skeletal muscle of nine patients with peripheral arterial disease and suffering from intermittent claudication were evaluated using 31phosphorus magnetic resonance spectroscopy (MRS) before and after treatment for 3 months with propionyl-L-carnitine (PLC; 2 g/day p.o.). Maximum walking distance (MWD) was assessed on a standard treadmill (4 km/h, zero incline). For the group as a whole 31P MRS results did not change significantly with PLC. Although MWD increased by a mean of 36%, this change did not reach significance. However, when these variables were assessed with respect to the change in MWD, there were significant differences between those who increased MWD by > 30% (responders, R; n = 5) and those who did not (nonresponders, NR; n = 4). Compared with pretreatment values, during exercise the decrease in muscle pH in R relative to the decrease in phosphocreatine was less after PLC (p = 0.04). After exercise there was a significant inverse correlation between the changes in recovery half-time (t1/2) for phosphocreatine and in MWD (r = -0.91, p = 0.01). With PLC, Vmax increased in R (p = 0.04), but not in NR. For the patient group as a whole, the changes in Vmax and MWD correlated positively (r = 0.90, p = 0.01). This study helps to identify the changes in muscle metabolism that correlate with changes in exercise performance, and may accompany treatment with PLC.

Adenosine Diphosphate↗
PubMed1996

Principles of angioplasty guidance using ultrasound.

Marker bands that cast dense shadow on X-ray are placed at crucial points on a catheter (for example on a peripheral angioplasty catheter on either side of the balloon) so that those parts of the catheter can be guided inside the body by X-ray. For catheter guidance by ultrasound, an ultrasound sensor in the mid-balloon region of an angioplasty catheter is integrated to the scanhead of an ultrasound scanner, via a catheter system interface (CSI). When the sensor in the catheter is imaged by the ultrasound scanner, the CSI injects a bright arrow corresponding to its position. This allows accurate catheter guidance using ultrasound. This paper describes the principles of ultrasound guidance of catheters and the initial clinical experience using this new catheter system (Echomark) in carrying out peripheral transluminal angioplasty.

Angioplasty↗
PubMed1996

Vasa vasorum visualised by power-Doppler in normal and arteriosclerotic carotid arteries.

Vasa vasorum and the perfusion of the carotid wall in normal arteries and in arteries with arteriosclerotic plaques was evaluated in-vivo using power-Doppler. Two types of arteries were studied using high-resolution ultrasound. These were arteries with a normal wall (intima, media and adventitia clearly separated) and arteries with intima-media thickening and plaques without calcification. In 10 normal subjects and in 10 patients with early plaques vasa vasorum were visualised. On power-Doppler they appeared as distinct, glomerular-like perfusion units, regularly placed along the course of normal arteries and at similar distance (2 to 4 mm from the lumen-wall interface, within the adventitia and periadventitia layers). In arteriosclerotic vessels the distribution of vasa vasorum units was more irregular, often concentrated in one spot with some perfusion units more distant from the lumen (between 2.5 and 5 mm) and their pulsatility was reduced. Flow velocity complex in most vasa vasorum was comparable, in lower scale to the pattern observed in the carotid lumen without significant differences between normal and arteriosclerotic arteries. The average peak systolic flow velocity was 15: +/-4 cm/sec and the average diastolic velocity was 6 +/- 4 in normal arteries with a median pulsatility index of 1.8 (range 2.2-1.05); in arteriosclerotic arteries velocities were 13 +/- 4 (peak systolic) and 3 +/- 2 (end diastolic) with a median pulsatility index of 1.71 (range 2.1-1.1). In conclusion a different, apparent distribution of vasa vasorum was observed in normal carotids and in carotids with arteriosclerotic lesions.

Adult↗