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Biomedical subjects

A Fronek

Publications and source records attributed to A Fronek.

At least 19 recordsLinked to original sources
PubMed1992

Mortality over a period of 10 years in patients with peripheral arterial disease.

BACKGROUND: Previous investigators have observed a doubling of the mortality rate among patients with intermittent claudication, and we have reported a fourfold increase in the overall mortality rate among subjects with large-vessel peripheral arterial disease, as diagnosed by noninvasive testing. In this study, we investigated the association of large-vessel peripheral arterial disease with rates of mortality from all cardiovascular diseases and from coronary heart disease. METHODS: We examined 565 men and women (average age, 66 years) for the presence of large-vessel peripheral arterial disease by means of two noninvasive techniques--measurement of segmental blood pressure and determination of flow velocity by Doppler ultrasound. We identified 67 subjects with the disease (11.9 percent), whom we followed prospectively for 10 years. RESULTS: Twenty-one of the 34 men (61.8 percent) and 11 of the 33 women (33.3 percent) with large-vessel peripheral arterial disease died during follow-up, as compared with 31 of the 183 men (16.9 percent) and 26 of the 225 women (11.6 percent) without evidence of peripheral arterial disease. After multivariate adjustment for age, sex, and other risk factors for cardiovascular disease, the relative risk of dying among subjects with large-vessel peripheral arterial disease as compared with those with no evidence of such disease was 3.1 (95 percent confidence interval, 1.9 to 4.9) for deaths from all causes, 5.9 (95 percent confidence interval, 3.0 to 11.4) for all deaths from cardiovascular disease, and 6.6 (95 percent confidence interval, 2.9 to 14.9) for deaths from coronary heart disease. The relative risk of death from causes other than cardiovascular disease was not significantly increased among the subjects with large-vessel peripheral arterial disease. After the exclusion of subjects who had a history of cardiovascular disease at base line, the relative risks among those with large-vessel peripheral arterial disease remained significantly elevated. Additional analyses revealed a 15-fold increase in rates of mortality due to cardiovascular disease and coronary heart disease among subjects with large-vessel peripheral arterial disease that was both severe and symptomatic. CONCLUSIONS: Patients with large-vessel peripheral arterial disease have a high risk of death from cardiovascular causes.

Adult↗
PubMed1991

Determination of in vitro simulated blood cell velocity by laser-Doppler with state space methods.

In this paper a signal processing method based on an important tool of numerical analysis, the singular value decomposition (SVD), is used. This method is applied to the unprocessed output of a Laser-Doppler fluxmeter to obtain parameters that are more sensitive to blood velocity than to hematocrit. The SVD-based method utilizes the exponential shape of the frequency spectrum of the laser light scattered from the moving red blood cells and demonstrates an inverse relationship between the damping constant beta associated with the exponential shape and the blood velocity. This method was applied to samples of rat blood of several known hematocrit values that were rotated at different velocities on a turntable. The method extracted one dominant singular value from the spectra, indicating that the spectra can be modeled as a single exponential dominated by scatterings with a single moving red blood cell. A 68% change in inverse velocity resulted in a 50% change in the damping constant (hematocrit 29.5% vol). On the other hand, a 37% change in hematocrit resulted in a far smaller change in the damping constant beta of only 17%. Analysis of the extracted parameters shows that the damping constants are far more influenced by blood velocity than by blood hematocrit.

Animals↗
PubMed1991

Coronary disease and stroke in patients with large-vessel peripheral arterial disease.

Previous reports have indicated an excess of mortality from coronary heart disease (CHD), cardiovascular disease (CVD), and all causes in subjects with large-vessel peripheral arterial disease (LV-PAD). However, there is little information available concerning the risk of nonfatal events (morbidity) in this patient group. In a population-based study of 67 patients with LV-PAD and 408 control subjects without this condition, nonfatal CHD and stroke, and total CVD events, morbidity and mortality were evaluated in both men and women. Those with LV-PAD had a 3-fold excess of CVD morbidity at baseline compared with control subjects of the same sex. However, the absolute CVD rates were greater in men than women. During the 10 years of follow-up, women with LV-PAD had more nonfatal CVD events than men, resulting in comparable overall morbidity rates. In logistic regression models adjusted for other CVD risk factors, total CVD morbidity and mortality combined with 2.5 times as great in men and 5 times as great in women with LV-PAD as in those without peripheral arterial disease. These results suggest that the total morbidity and mortality burden are dramatically increased in both men and women with LV-PAD.

Adult↗
PubMed1991

[D-SGP Duo--a new plethysmography for acral, arterial and venous blood pressure measurement].

This is to present a new portable plethysmograph using modern microprocessor technology, a two-channel digital strain gauge plethysmograph (D-SGP Duo). This system contains two strain gauges and a pressure gauge and has measuring programmes for thrombosis screening (venous occlusion test) and for the acral blood pressure measurement. For the first time it is possible to determine not only the acral systolic arterial pressure but also the acral venous blood pressure. Examples of application are given.

Blood Pressure↗
PubMed1991

Real-time color duplex scanning after sclerotherapy of the greater saphenous vein.

A color real-time duplex scanner was used to scan the greater saphenous vein in 89 limbs of 55 patients to study the efficacy of prior greater saphenous vein sclerotherapy. The greater saphenous vein was insonated from the saphenofemoral junction to the knee to evaluate both reflux to a standardized 30 mm Hg Valsalva maneuver and evidence of greater saphenous vein obliteration by sclerotherapy. These data were correlated with the number of sclerosing injections used (mean, 1.8; range, 1 to 6), time from the last injection (mean, 27.5 mo.; range, 3 to 55 mo), and concentration of injectant used (0.5% to 3% sodium tetradecyl sulfate). Fifty-one of 89 injected limbs (57%) demonstrated reflux through the saphenofemoral junction, and reflux down the more distal greater saphenous vein was found in 67 of 89 injected limbs (75%). Greater saphenous vein obliteration was noted in only 18 of 89 injected limbs (20%); two were totally obliterated, and 16 were partially obliterated. The greater saphenous vein was obliterated in 6% below a refluxing saphenofemoral junction and in 40% below a nonrefluxing junction. A greater saphenous vein obliteration rate of 9% was found with a refluxing greater saphenous vein, and 50% in a nonrefluxing greater saphenous vein. Femoral vein reflux was identified in 11 of the 110 limbs (10%) and in every case was associated with both saphenofemoral junction and greater saphenous vein reflux. We noted a trend toward more successful results with more concentrated injectate (3% sodium tetradecyl sulfate). Fifty percent of patients reported improvement in symptoms.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1979

Quantitative transcutaneous arterial velocity measurements with Doppler flowmeters.

A controlled in vitro and in vivo comparative evaluation of four Doppler ultrasonic blood velocimeters was performed to evaluate their ability to measure fluid velocity throughout a wide range of flow rates and velocity profiles, during both steady and pulsatile flow. The instruments tested were the Versatone Bidirectional Doppler M-9, the Sonicaid BV380, the Parks 806 B, and the Delalande DUD 400. All instruments responded linearly to velocities of from 5 to 70 cm/s, and were accurate to within 5% through a wide range of in vitro changes in velocity, pulse frequency, and cross-sectional velocity profile. Quantitative velocity measurements and their derivatives are an inexpensive, simple, and useful tool in the evaluation conditions of patients with peripheral vascular disease, and widespread clinical trials of their value are appropriate at this time.

Animals↗
PubMed1979

Forearm arterial injuries.

The effects of single forearm arterial injuries with and without associated neurological injuries were studied. Fifty subjects were evaluated: seven patients with isolated arterial lacerations, 15 patients with isolated nerve lacerations, 13 patients with combined nerve and arterial injuries, and 15 control subjects. A series of noninvasive peripheral vascular studies were correlated with the symptoms produced by a controlled cold-environment exposure. The hemodynamic alterations associated with symptoms of hand ischemia, and particularly with cold intolerance, were studied. Unrepaired single arterial injuries caused modest, consistent alterations in hand vascularity, but few signs of ischemia or symptoms of cold intolerance. The remaining intact artery demonstrated a consistent increase in flow velocity. Combined nerve and artery injuries caused the most significant alterations in hand vascularity, and median nerve and associated artery injuries caused the most disabling symptoms. Single arterial lacerations had no effect on the rate or completeness of recovery from associated nerve injuries.

Arteries↗
PubMed1978

The importance of combined multisegmental pressure and Doppler flow velocity studies in the diagnosis of peripheral arterial occlusive disease.

The value of combined multisegmental pressures and quantitative Doppler flow velocity determinations in the preoperative vascular laboratory evaluation was analyzed in 100 consecutive patients with angiographically documented peripheral arterial occlusive disease. Several new observations were made: (1) erroneously normal or even high segmental pressure readings appear to be caused by increased arterial wall stiffness and may produce falsely elevated or erroneously normal pressure, suggesting less disease than exists, especially when only ankle pressure screening is used. (2) The addition of quantitative flow velocity determinations significantly improved the reliability of diagnostic decision making. The diagnosis of proximal arterial occlusive disease based on combined pressure-velocity measurements was confirmed angiographically in 143 of 148 limb studies (96.6%), including several with normal pressures and reduced velocity values--a pressure-velocity dissociation. (3) A decrease of the leg segment:arm pressure ratio combined with only a slight reduction of velocity indices suggests a stenosis with good local collateral flow and vessel patency at the site of measurement--a reversed pressure-velocity dissociation. (4) A decreased lower limb segment/arm pressure ratio combined with a significant reduction of velocity indices is evidence of arterial stenosis with poor local collateral flow. The combined multisegmental pressure and velocity evaluation of patients suspected of arterial occlusive disease substantially increases the reliability of noninvasive diagnosis and offers a new level of differential diagnostic interpretation.

Ankle↗
PubMed1977

A microscope-television system for studying flow velocity in human skin capillaries.

A noninvasive technique for studying blood flow dynamics in human skin capillaries is described. A light microscope combined with a closed-circuit TV system was used to monitor and record capillary blood flow velocity on video tape. Arterial pulsations were recorded plethysmographically and converted into video signals by modulating the position of a square, white area in the televised scene. Twelve healthy subjects were studied. The mean (+/- SD) resting capillary blood flow velocity was 0.65 +/- 0.3 mm/s at an average skin temperature of 30.4 +/- 2.3 degrees C. Spontaneous fluctuations at a frequency of 6-10 cycles/min were observed in most subjects. A well-pronounced flow pulsatile component could be demonstrated in all capillaries studied. The technique can be used in clinical practice for studying the physiology and pathophysiology of cutaneous microcirculation in man. It can be expected that the method may become an important diagnostic tool in diseases that involve disturbances of the microcirculation, such as diabetes, hypertension, and atherosclerosis.

Capillaries↗
PubMed1977

The pulse-reappearance time: an index of over-all blood flow impairment in the ischemic extremity.

A simple test is described to evaluate limb blood supply. The technique utilizes the delayed reappearance of the volume pulse after transient arterial occlusion. As monitored from the toe by a mercury-in rubber gauge, pulse reappearance (PRT) was instantaneous (less than one second) and the 50 percent of control amplitude reappearance time (PRT/2) was 3.4 +/- 0.8 seconds in 22 control subjects. A significant delay of the PRT and especially of PRT/2 was found in 60 patients with angiographically documented ischemic disease of the lower extremities. The delay was correlated closely with the severity of the disease: the mean PRT/2 for single level arterial disease (aortoiliac, femoropopliteal, posterior tibial, or anterior tibial artery obstruction) was approximately 25 seconds, and the mean PRT/2 associated with multilevel occlusion was 71 seconds. Since the technique is very simple, it may be used as a quick screening and follow-up procedure to detect the presence and over-all severity of peripheral arterial occlusive disease.

Arterial Occlusive Diseases↗
PubMed1976

Quantitative ultrasonographic studies of lower extremity flow velocities in health and disease.

Quantitative Doppler ultrasonographic flow velocity determinations are reported from 39 normal control subjects and 80 patients with angiographically documented peripheral arterial disease, in whom femoral, posterior tibial and dorsalis pedis arteries were studied. The mean control values of the most useful parameters were: femoral artery: peak forward velocity (PFV) cm/sec: 40.7 +/- 10.9, deceleration (Dec.) cm/sec2:250.9 +/- 60.0, peak/mean velocity (P/MV): 4.8 +/- 1.6; posterior tibial artery: PFV: 16.0 +/- 10.0, Dec.: 129.8 +/- 75.7, P/MV: 4.8 +/- 2.5; dorsalis pedis artery: PFV: 168 +/- 5.7, Dec.: 137.9 +/- 54.5, P/MV: 6.0 +/- 4.1. The values of these measurements in the patients with arterial occlusive disease were all significantly lower, and also permitted distinguishing those with multilevel disease from those with a single site of occlusion. Quantitative evaluation of the Doppler ultrasonogram permits obtaining detailed functional information on the degree of arterial flow impairment in patients with peripheral arterial occlusive disease.

Adult↗