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Biomedical subjects

F Mahler

Publications and source records attributed to F Mahler.

At least 163 records · Page 9Linked to original sources
PubMed1977

Changes in phasic femoral artery flow induced by various stimuli: a study with percutaneous pulsed Doppler ultrasound.

Transcutaneous blood flow measurements were performed by means of pulsed Doppler ultrasound flowmeter in the femoral artery of healthy subjects. The pulsatile flow pattern was changed characteristically from resting state by postocclusive reactive hyperaemia, by the application of amyl nitrite, xanthinol nicotinate, and angiotensin amide. During reactive hyperaemia systolic flow was increased, diastolic reverse flow was abolished, and the forward flow continued throughout diastole. Amyl nitrite augmented thenegative flow phase and reduced mean flow, while xanthinol nicotinate decreased the negative component and augmented mean flow. Angiotensin amide produced enhancement of the average flow by elevating systolic and diastolic flow equally over the base line. In each of these interventions the changes in flow were determined mainly by variations during the diastolic flow phase.

Adult↗
PubMed1976

[Experiences with Dotter's percutaneous recanalization of chronic arterial occlusions].

Since 1971 141 patients (mean age 66 years, range 46-85 years) with chronic occlusions of the pelvic (19) and superficial femoral popliteal arteries (122) have been treated by the percutaneous recanalization technique first described by Dotter and Judkins in 1964. Since 1974 we have employed a modification of the original Dotter technique. The occluding material is removed with a double-lumen distensible catheter introduced over a guide wire. Primary success was achieved in 117 (83%) patients. Re-occlusions occurred in 18 patients after 6 months and in 5 patients in the second half of the first year, giving an overall patency rate of 75%. Up to now no further re-occlusions of dilated arterial segments have been observed. Indications for this treatment as compared with vascular surgery are discussed.

Aged↗
PubMed1976

Measurement of foot artery blood pressure by micromanometry in normal subjects and in patients with arterial occlusive disease.

Blood pressure was measured continuously in the posterior tibial or dorsalis pedis arteries using an isovolumetric system (steel cannulas of 0.18 mm, external diameter). The systolic values in the ankle arteries of 13 normal subjects at rest (154.3 +/- 22.3 mm Hg) exceeded the systolic arm pressure (128.9 +/- 20.1 mm Hg, P less than 0.001), while diastolic values (69.9 +/- 8.7 mm Hg) were not significantly different from the arm pressure. In 13 patients with arterial occlusive disease (AOD) the dicrotic notch, normally situated close to the footpoint of the downslope, was either displaced upward or abolished. Both mean systolic and diastolic values (94.9 +/- 35.9 mm Hg and 62.5 +/- 18.5 mm Hg, respectively) and also mean pressure amplitude were reduced compared to the corresponding arm values (158.5 +/- 28.2 mm Hg and 87.7 +/- 6.0 mm Hg, respectively, all P less than 0.001). Comparison between the systolic pressure values measured by micromanometry and by an indirect technique using Doppler ultrasound showed a good correlation (r = 0.87). During postocclusive reactive hyperemia, the initial pressure values were markedly diminished in normal subjects and reached control values within 40 sec. In patients with AOD, however, this reduction in pressure was more pronounced and prolonged. Flow measurements using plethysmography showed flow diversion from the foot to the calf as long as pressure values ranged below 40 mm Hg. This almost painless method appears useful for experimental and diagnostic studies in low pressure areas of the peripheral circulation.

Adult↗
PubMed1976

[The significance of the veins for transcapillary fluid balance].

Various results from experimental as well as from theoretical studies challenge the classical concept of the Starling hypothesis of fluid balance between blood and tissue. Although most of these considerations are based on work with animal preparations, the following points appear to be applicable to human physiology: 1. The values of pressure as measured directly in venules, prohibit reabsorption of fluid from the interstitium. In addition, due to the increased permeability of the venular vessel wall to macromolecules, filtration of plasma proteins takes place at the venular end of the capillaries. 2. The overall permeability of the vessel walls to the proteins, is up to 20 times smaller than was previously assumed. Therefore, the total amount of filtered fluid is reduced to the volume range of the lymphatic transport. 3. The total amount of filtered proteins is brought back to the blood circulation via the lymphatic system. Thus, there is unidirectional slow movement of macromolecules with free fluid from the capillaries across the interstitial space toward the terminal lymphatics. However, exchange of small molecular substances such as water, gases, minerals and sugar by diffusion, is practically unlimited by the blood-tissue barrier. 4. As a practical example, the pressure values in the superficial veins of the human leg clearly exceed the limits for reabsorption of fluid from the tissue. The absence of edema in the normal human legs remains unexplained, if the lymphatic transport is not taken into account as an essential part of the system. Thus, the dynamic equilibrium of the fluid exchange is disturbed, either by increased transcapillary filtration (e. g. increase in venous pressure or microvascular permeability), by impaired lymphatic capacity or by a combination of these two factors.

Capillaries↗
PubMed1975

[Proceedings: The ankle arterial pressure during reactive hyperemia in healthy patients and patients with arterial occlusive disease].

In 8 healthy subjects and in 16 patients with arterial occlusions in the iliac or ilio-femoral region ankle blood pressure and blood flow velocity were measured by Doppler ultrasound during postocclusive reactive hyperemia. In the normal subjects the ankle blood pressure decreased significantly within the initial 30 sec after release of the occlusion. The pressure values showed a negative relation to the simultaneous increases in flow velocity (r = 0.67). In the patients the pressure decreased further and the reduction was prolonged with the protracted course of the reactive hyperemia.

Ankle↗
PubMed1975

Effects of changes in preload, afterload and inotropic state on ejection and isovolumic phase measures of contractility in the conscious dog.

Despite much investigation, the usefulness of various indexes employed clinically for detecting alterations in ventricular contractility in the intact circulation remains controversial. The effects of acute preload, afterload and contractility changes on both ejection and isovolumic phase measures of left ventricular function were analyzed in normal, trained conscious dogs instrumented with micromanometers and endocardial ultrasonic diameter gauges. Rapid volume overload increased the excursion of the left ventricular diameter (delta LVD) by 7 percent above the control level, but mean velocity of circumferential shortening (VCF) did not change significantly; peak rate of left ventricular pressure rise (dP/dt) increased by 11 percent and (dP/dt)/DP40 (DP = developed pressure) was augmented by 10 percent, but maximal [(dP/dt)/LVP], or "Vpm," decreased by 20 percent. Pressure overload by phenylephrine infusion decreased delta LVD by 15 percent and mean VCF fell by 26 percent; peak dP/dt and (dP/dt)/DP40 remained unaltered, but VPM was reduced by 37 percent. Isoproterenol augmented peak dP/dt by 55 percent, and (dP/dt)/DP40, Vpm and mean VCF were increased comparably. Propranolol decreased these measures equally by about 16 percent. Therefore, in the conscious animal in the steady state, isovolumic phase indexes were mildly influenced by acute volume loading, wheras ejection phase indexes were not. Acute increases in aortic pressure markedly reduced ejection phase measures, whereas the isovolumic indexes were unaffected. All of the indexes studied were comparably sensitive to acute alterations in contractility, but we conclude that no single measure can always be used for defining an acute contractility change in the intact circulation.

Animals↗
PubMed1975

Systolic pressure--diameter relations in the normal conscious dog.

Pressure--diameter loops were generated in normal, conscious dogs during left ventricular contraction by means of endocardial ultrasonic gauges and micromanometers. Studies were made in the control state, during volume and pressure loading, and during enhancement of contractility. The diameter at the end of ejection was linearly related to systolic pressure, and the pressure--diameter relation at end-ejection was not affected by changes in preload. However, this relation was substantially displaced by changes in inotropic state, suggesting that the instantaneous pressure--length plane produced by pressure loading is unique to a given level of contractility.

Animals↗