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H Rieger

Publications and source records attributed to H Rieger.

At least 19 recordsLinked to original sources
PubMed1992

Validation of Doppler measurement of pressure gradients across peripheral model arterial stenosis.

Hemodynamic assessment of aortoiliac occlusive disease is necessary for successful arterial reconstruction of the legs. Various methods have been proposed, and the "pull through" intraarterial pressure measurement method is accepted as the best standard. The pressure readings, however, seemed to depend on the intraluminal position of the catheter. To explain these observations and make a comparison between the Doppler method and the pull through method, we have studied centerline velocity changes at the stenosis throat by Doppler ultrasonography, and axial and lateral pressure gradients by use of pressure transducers mounted 10 mm and 40 mm downstream of short (4 mm) axisymmetric sharp-edged model stenoses having cross-sectional reduced areas of 64%, 84%, 91%, and 96%. Axial manometric pressures measured 10 mm beyond the throat of 84% stenosis were more than twice as high as the lateral pressures. No significant difference was observed between axial and lateral pressures measured 40 mm downstream from the throat. This pressure distribution has important clinical relevance. Mean and peak pressure gradients for both the Doppler method and manometric measurements were compared. Measurements with Doppler method and manometric measurements indicated that mean pressure gradients (r = 0.98; SEE = +/- 2.4 mm Hg) correlate better than peak pressure gradients (r = 0.90; SEE = +/- 16.5 mm Hg). Doppler gradients were higher than manometer gradients. Overestimation was 13% for mean pressure gradients and ranged from 10% to 150% for peak pressure gradients. Explanation for the difference between mean Doppler and catheter gradient may be the pressure recovery occurring in the relaminarized poststenotic regions.

Arterial Occlusive Diseases↗
PubMed1992

Influence of clinical findings, positional manoeuvres, and systolic ankle arterial pressure on transcutaneous oxygen tension in peripheral arterial occlusive disease.

The mutual effects of systolic ankle arterial pressures, positional manoeuvres, and calf artery occlusions on transcutaneous oxygen partial pressures (tcpO2) were studied in 388 legs of 258 patients with peripheral arterial occlusive disease (PAOD). The tcpO2-vs-perfusion pressure relationship could be satisfactorily fitted by a non-linear regression model deduced from the tcpO2 theory. Flow-insensitive ranges of tcpO2-vs-flow hyperbolas were reduced by both leg lowering and moving the electrode towards proximal measuring sites. Lower tcpO2 values were found in case of occluded compared to patent calf arteries at ankle arterial pressure indices below 0.4. The tcpO2 positional variability increased with worsening hemodynamic compensation and was most pronounced in critical limb ischaemia (ischaemic rest pain, non-healing ulcerations). According to a retrospective analysis, a critical ischaemia could be assumed if supine and sitting tcpO2-values exceed neither 10 nor 45 mmHg, respectively.

Adult↗
PubMed1992

Redistribution of skin blood flow during leg dependency in peripheral arterial occlusive disease.

A disturbed autoregulation of cutaneous blood flow in legs with peripheral arterial occlusive disease (PAOD) has previously been demonstrated for circumscribed skin areas. In the present study, posturally-induced changes of skin perfusion distribution along ischaemic limbs were investigated topographically in 35 PAOD patients by means of fluorescein perfusography. Among the 68 legs studied, 7 had patent arteries and 61 could be assigned to FONTAINE stages I to IV. Limbs with peripheral skin lesions (stage IV) were further differentiated according to either healing (stage IV+) or non-healing (stage IV-) on conservative treatment. Sitting-up always led to prolonged calf as well as foot fluorescein appearance times (AT) except for legs in stage III or IV- disease. In the latter two groups, decreased sitting as compared to supine AT foot-to-calf ratios indicated a relative shift of dye delivery from proximal towards distal skin regions during posture. In contrast, this measure of blood flow redistribution did not change in the other groups. The redirection of fluorescein influx was significantly correlated with the systolic arterial pressure ankle-to-arm ratios. In conclusion, besides small perfusion pressure increases or passive microvessel distension, a shift of the peripheral resistance ratios may contribute to the improved blood supply of ischaemic skin regions during leg dependency. An arteriolar vasoparalysis does not regularly exist in limbs with skin lesions not primarily originating from ischaemia (stage IV+).

Adult↗
PubMed1992

A comparative analysis of transcutaneous oximetry (tcPO2) during oxygen inhalation and leg dependency in severe peripheral arterial occlusive disease.

Transcutaneous oximetry (tcPO2) performed during either oxygen inhalation or leg dependency was intra-individually compared in 64 patients suffering from a peripheral arterial occlusive disease, with and without critical limb ischemia. Among the 81 extremities investigated, 29 had a moderate peripheral arterial occlusive disease (6 in stage I, 23 in stage II) and 52 were initially affected by rest pain or ulceration (stage III/IV). Thirty-seven legs out of the latter improved under conservative treatment. In the remaining 15 limbs, vascular surgery or an amputation became necessary. The tcPO2 was measured at the forefoot with the patient in supine and sitting positions while breathing room air and in the supine position while inhaling 100% oxygen. In limbs with a tcPO2 below 15 mm Hg of patients in the supine position breathing room air, leg dependency generally provoked larger tcPO2 increases than oxygen inhalation. This difference between oxygen inhalation while supine and room air breathing leg dependency tcPO2 values exhibited an approximately linear correlation with the resting tcPO2. Responses of tcPO2 to leg dependency and oxygen inhalation seemed to reflect different mechanisms, that is, microvascular flow redistribution and supine perfusion reserve, respectively. The best discrimination of critical limb ischemia was observed for the tcPO2 of patients breathing room air while in the supine position, which was not surpassed by either the oxygen inhalation or the leg dependency test. Satisfactory results were achieved by combining limits for, first, supine (10 mm Hg) and sitting (45 mm Hg) tcPO2, as well as, second, ankle arterial pressure (60 mm Hg) and supine tcPO2 (10 mm Hg).

Adult↗
PubMed1992

Spontaneous oscillations of laser Doppler skin blood flux in peripheral arterial occlusive disease.

In the present study, local temporal fluctuations of skin perfusion were non-invasively measured at the forefoot and calf in 374 limbs of 226 patients with peripheral arterial occlusive disease (PAOD) by means of Laser-Doppler-Flowmetry (LDF). Within the scope of a purely descriptive evaluation, each recording was classified according to four previously defined LDF oscillation types named 'aperiodical', 'sinoidal', 'missing waves', and 'small waves'. The prevalences of these curve patterns distinctly varied with both the macrohemodynamic compensation and clinical severity of PAOD. While type 'aperiodical' predominated in case of a normal or only slightly affected circulation, type 'sinoidal' accumulated in legs with marginal collateralization. In contrast, 'missing waves' and 'small waves' mainly occurred in feet affected by severe PAOD. Which pathophysiological mechanisms are responsible for the different LDF oscillation types still remains to be clarified. Retrospectively, in case of a confirmed PAOD, the diagnosis of critical limb ischemia could not be established and wound healing could not be predicted by means of LDF pattern analysis.

Adult↗
PubMed1992

[Changes in systemic fibrinolysis and blood coagulation parameters in local thrombolysis with tissue plasminogen activator (rt-PA)].

During the local fibrinolysis with rt-PA (2.5 mg/h) systemic plasminogen and alpha 2-antiplasmin activities slightly decrease, but the fibrinolytic system is compensated during the whole treatment. The d-dimer plasma levels increase dependently on the mass of thrombus. Despite the administration of high doses of heparin during the fibrinolysis thrombin is formed, measured as thrombin-antithrombin III complex (TAT).

Blood Coagulation↗
PubMed1992

Clinical information content of transcutaneous oxymetry (tcpO2) in peripheral arterial occlusive disease (a review of the methodological and clinical literature with a special reference to critical limb ischaemia).

About 160 publications (1978-1992) dealing either directly or indirectly with transcutaneous oxygen partial pressure measurements (tcpO2) in peripheral arterial occlusive disease (PAOD) are reviewed. Thereby, various clinical applications and results are related to the theory and methodology of the tcpO2 technique. In PAOD patients, the tcpO2 reflects local hyperemic skin blood supply. The clinically relevant intersection of the tcpO2-flow hyperbola is of considerably non-linear shape and partially insensitive to flow. In view of macrocirculatory pathology, tcpO2 values depend particularly on PAOD staging, hemodynamic compensation, and calf artery patency. Pathophysiological and pharmacological microcirculatory effects, however, cannot be read unequivocally from corresponding tcpO2 responses due to the heat-induced local vasoparalysis. In daily practice, the tcpO2 does not provide substantial information in patients with asymptomatic obstructions (Fontaine stage I) or intermittent claudication (stage II) but is of clinical impact in limbs with rest pain and skin lesions (stages III and IV). In such a complicated PAOD, diagnostic and prognostic capabilities can be essentially improved by provocational manoeuvres which narrow the flow-insensitive range. A critical limb ischaemia may be assumed if supine and dependent foot tcpO2 values exceed neither 10 mmHg nor 45 mmHg, respectively.

Arterial Occlusive Diseases↗
PubMed1991

[Duplex sonographic determination of blood pressure gradient in iliac artery stenoses. Comparison with invasive measurement].

The present study investigates the validity and accuracy of the simplified Bernoulli equation in the duplex-derived determination of pressure gradients across iliac artery stenoses. 28 patients presenting with iliac artery stenoses were examined by both duplex scanning and intraarterial catheter pressure measurement. The catheter-determined and duplex-derived mean pressure gradient was 16 +/- 7 and 14 +/- 7 mmHg, respectively. There was a fairly good correlation between the mean pressure gradients assessed nonsimultaneously by both methods (r = 0.77). The catheter-determined and duplex-derived maximum instantaneous pressure gradient was 53 +/- 16 and 52 +/- 21 mmHg, respectively. The correlation coefficient (r) for the maximum instantaneous pressure drop values determined by the two methods was r = 0.79. The results show that duplex ultrasound predicts mean and maximal-instantaneous pressure gradients with acceptable approximation in patients with iliac artery stenoses.

Adult↗
PubMed1991

Traumatic dislocation of the hip in young children.

Traumatic dislocation of the hip joint is an uncommon injury in children. The present report on this traumatic emergency is based on the authors' own observations of three cases and a review of the literature. The main problem is the possible development of avascular necrosis of the femoral head. The crucial therapeutic intervention to avoid this serious complication seems to be immediate, usually closed, reduction under general anaesthesia. A management protocol is presented.

Accidental Falls↗
PubMed1991

Use of duplex scanning in the diagnosis of arteria profunda femoris stenosis.

To evaluate the accuracy of duplex scanning in diagnosing arteria profunda femoris stenoses in patients with concomitant superficial femoral artery occlusions, 123 femoral artery bifurcations were examined in 103 patients. Peak systolic and time-averaged maximal flow velocity parameters were measured in the arteria profunda femoris and compared with independently performed angiography. For detecting stenoses greater than 30% diameter reduction (50% by area) of the arteria profunda femoris, duplex scanning had a sensitivity of 91% and 96%, a specificity of 85% and 98%, a positive predictive value of 86% and 98%, and a negative predictive value of 91% and 96%, for a peak systolic velocity of 180 cm/sec and more, and for a time-averaged maximal velocity of 50 cm/sec and more in the arteria profunda femoris, respectively. The day-to-day variability for peak systolic and time-averaged maximal velocity parameters was low with correlation coefficients between velocity measurements on both days of 0.96 and 0.98 (n = 20), respectively. In 10 patients with arteria profunda femoris stenoses and superficial femoral artery occlusions, undergoing percutaneous transluminal angioplasty of arteria profunda femoris stenosis, the duplex scan revealed a reduction in stenotic peak systolic velocity from 330 +/- 84 to 163 +/- 50 cm/sec and a decrease in stenotic time-averaged maximal velocity from 156 +/- 47 to 54 +/- 17 cm/sec after the interventional procedure. These results show that peak systolic and time-averaged maximal velocities are accurate parameters to detect significant arteria profunda femoris stenosis in patients with superficial femoral artery occlusions.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Skin perfusion patterns (fluorescein perfusography) during reactive hyperaemia in peripheral arterial occlusive disease.

From the pathophysiological point of view the regional distribution of blood flow is of special importance in ischaemic tissues. Within this study foot sole skin perfusion was investigated by means of fluorescein perfusography at rest and during reactive hyperaemia in patients with peripheral arterial occlusive disease confined to one limb (Fontaine stage II). Ambient temperatures were maintained around 21 degrees C. Mean fluorescein appearance times on the one side and their standard deviations (SD) and coefficients of variation (CV) on the other side were taken as measures of overall blood supply and homogeneity of flow, respectively. At rest no differences in these parameters could be detected between diseased legs and controls. After a 3-min supra-systolic circulatory arrest at the thigh, a significant reduction of fluorescein appearance times was observed for both groups but was statistically more pronounced in the controls. Furthermore, during reactive hyperaemia standard deviations as well as coefficients of variation decreased significantly only in normal limbs whereas they either remained constant (SD) or even increased (CV) in those with arterial obstructions. All effects associated with reactive hyperaemia showed statistically significant correlations with systolic ankle pressure indices. From these results it is concluded that haemodynamically effective arterial obstructions are followed by not only a restriction of overall hyperaemic blood supply but also a failure to homogenize microcirculatory perfusion in the case of increased flow requirements.

Arterial Occlusive Diseases↗