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Biomedical subjects

A L Strauss

Publications and source records attributed to A L Strauss.

At least 19 recordsLinked to original sources
PubMed1992

[Why is the Doppler pressure gradient higher than the one measured by catheter?].

Hemodynamic assessment of aorto-iliac occlusive disease is necessary for successful arterial reconstruction of the legs. Various methods have been proposed and the "pull-through" intra-arterial 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 center-line velocity changes at the stenosis throat by Doppler ultrasound, and axial and lateral pressure gradients using pressure transducers, mounted 10 mm and 40 mm downstream of short (4 mm) and long (40 mm) axisymmetric sharp-edged model stenoses having cross sectional reduced areas of 64%, 84%, 91%, and 96%. Axial manometric pressures measured 10 mm after the throat of 84% stenosis were more than twice as high as the lateral pressures. There was no significant difference between axial and lateral pressures measured 40 mm downstream from 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 mmHg) correlate better than peak pressure gradients (r = 0.90; SEE = +/- 16.5 mmHg). Doppler gradients were higher than manometer gradients. Overestimation was 13% for mean pressure gradients, and ranging 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.

Aortic Valve Stenosis↗
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↗
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

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

[Is preoperative evaluation of the internal mammary artery for suitability in coronary bypass surgery possible?].

The internal mammary artery (IMA) is the preferred conduit for coronary artery surgery due to its high patency rate. In order to determine the role of preoperative duplex investigation of the IMA, preoperative noninvasive measurements of IMA diameter, blood velocity and blood flow were performed bilaterally in 30 patients eligible for coronary surgery. The diameter of the left and right IMA was 2.1(+) -0.2 mm and 2.2(+) -0.2 mm at the third intercostal space, respectively. Preoperative mean flow was 51 ml/min in the left and 54 ml/min in the right IMA. Due to the close proximity of the IMA to the sternal border (8 mm), care must be taken not to injure the IMA during routine sternal closure. In conclusion, noninvasive assessment of the patency of the IMA is possible prior to coronary artery surgery.

Blood Flow Velocity↗
PubMed1991

[Contribution of duplex sonography to prediction of pressure drop across iliac artery stenoses].

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. Twenty eight patients presenting with iliac artery stenoses could be examined by both duplex and intraarterial catheter pressure measurements. The correlations between mean and maximal-instantaneous pressure gradients assessed by both methods were r = .77 and r = .79, respectively. Duplex scan can be used to predict pressure gradients in patients with iliac artery stenoses.

Arterial Occlusive Diseases↗
PubMed1990

[Non-invasive determination of the hemodynamic significance of vasoconstriction: study of the arteria femoris profunda using ultrasound].

In case of occlusion of the superficial femoral artery (SFA), the profunda femoris artery (PFA) supplies the entire lower extremity. Not infrequently the SFA occlusion is associated with stenosis of the origin of the PFA. The angiographic study of the origin of PFA is often unsatisfactory. The purpose of the present study was to develop objective criteria for the diagnosis of the PFA origin stenosis by duplex scanning. In 60 patients, we examined 75 femoral bifurcations by duplex scanning and compared them with the independently performed angiography. Group I. (n = 20 PFA origins) consisted of 10 normal individuals. Group II. (n = 30 PFA origins) consisted of 25 patients with angiographically proven SFA occlusion and normal PFA. Group III. (n = 25 PFA origins) consisted of 25 patients with angiographically proven SFA occlusion and PFA orifice stenosis. We measured the maximal systolic and mean flow velocity in the orifice of the PFA at rest and during the maximal hyperemia following 3 min of ischemia of the lower leg. At rest, the maximal flow velocity in the groups I-III. was 60 +/- 15, 142 +/- 44 and 255 +/- 60 cm/s (p less than 0.01) and the mean flow velocity was 8 +/- 6, 32 +/- 9 and 96 +/- 42 cm/s (p less than 0.01). During hyperemia, the maximal and mean flow velocity for the groups I-III. was 59 +/- 15, 155 +/- 42 and 286 +/- 82 cm/s (p less than 0.01) and 8 +/- 5, 55 +/- 19 and 144 +/- 51 cm/s (p less than 0.01), respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Angiography↗
PubMed1990

Variability of Doppler ophthalmic pressure index with occlusive carotid artery disease.

To evaluate day-to-day variability of Doppler ophthalmic pressure index by means of the ophthalmomanometry-Doppler technique, bilateral ophthalmic artery pressure and indirect systemic blood pressure determinations were repeated within 1 month in 40 patients with clinically stable occlusive carotid disease. No difference in Doppler ophthalmic pressure and calculated pressure index between both days could be demonstrated. The standard deviation of differences in ophthalmic pressure index between first and second day measurements was 0.04. Correlation between bilateral ophthalmic pressure index measurements on both days was high (r = 0.93, n = 80). It is concluded that individual Doppler ophthalmic pressure index must change at least 0.08 before it can be considered significant. In 37 patients with occlusive carotid artery disease (greater than 60% diameter reduction) undergoing 38 endarterectomies, Doppler ophthalmic pressure index was evaluated before and after surgery. Mean +/- SD ipsilateral Doppler ophthalmic pressure index increased from 0.59 +/- 0.07 to 0.71 +/- 0.05 (p less than 0.001) after endarterectomy. In 12 patients with significant bilateral occlusive carotid disease, mean +/- SD contralateral Doppler ophthalmic pressure index increased from 0.54 +/- 0.05 to 0.61 +/- 0.06 (p less than 0.02), whereas contralateral pressure index in patients with unilateral disease showed no change (0.71 vs 0.71) after ipsilateral endarterectomy. These results indicate that carotid endarterectomy not only normalizes ipsilateral Doppler ophthalmic pressure index but also improves contralateral Doppler ophthalmic pressure index provided significant bilateral occlusive carotid disease is present.

Adult↗
PubMed1990

[Doppler ultrasound determination of pressure decrease in model peripheral arterial stenoses].

In a pulsatile in vitro flow model with mounted concentric peripheral arterial stenoses, we compared the mean trans-stenotic pressure difference between pre- and poststenotic segment with the Doppler-estimated mean pressure gradient calculated according to the simplified Bernoulli equation applied over an entire stroke cycle. A close linear correlation was found between Doppler-estimated and invasively measured pressure drop values: Y = 1.13X + 0.47 (r = 0.98, SEE = 1.4 mmHg, n = 16). The Doppler-derived overestimation of the invasively measured mean pressure-drop by an average of 16% (absolute values 2.2 +/- 1.7 mmHg) suggests that in this in vitro model a small part of the kinetic energy of the stenotic jet is recovered distal to the poststenotic turbulences. The difference between both methods is so little that the Doppler-estimated mean pressure drop is acceptable in concentric peripheral model arterial stenoses.

Arterial Occlusive Diseases↗
PubMed1989

[Doppler-ophthalmomanometry in patients with obstruction of the carotid arteries].

A novel noninvasive method to determine simultaneously ophthalmic artery pressure (OAP) and flow direction based on Doppler ultrasound principles is presented: ophthalmomanometry-Doppler (OMD). Studies performed on 25 angiographically proven normal subjects with direct recording of the internal carotid artery pressure (ICP) and indirect determination of the brachial artery pressure (BAP) demonstrated that OAP values assessed by the OMD device are highly correlated with simultaneous ipsilateral intraarterial systolic ICP measurements (r = 0.95, n = 10) and with simultaneous recordings of the BAP (r = 0.88, n = 15). In 50 patients presenting angiographically occlusions and 52 patients presenting angiographically stenoses (greater than 60%) of the carotid artery the measured Doppler ophthalmic pressure index (OPI = ratio of the ophthalmic to systemic blood pressure) was lower ipsilateral to an occlusion (0.46 +/- 0.08) than ipsilateral to a stenosis (0.54 +/- 0.08; p less than 0.001) of the carotid artery. In both it was clearly diminished compared to normal values (0.68 +/- 0.04; p less than 0.001). In carotid artery occlusions, the ipsilateral OPI was 0.46 +/- 0.06 for antegrade (n = 17) and 0.46 +/- 0.09 for retrograde (n = 28) ophthalmic artery flow. In carotid artery stenoses, the ipsilateral OPI was 0.55 +/- 0.07 for antegrade (n = 41) and 0.48 +/- 0.06 for retrograde (n = 9) ophthalmic artery flow (p less than 0.01). It is concluded that in carotid occlusions presenting a longer disease history extra-intracranial collateralisation via the ophthalmic artery are as efficient as a functional circle of Willis.

Blood Pressure Determination↗
PubMed1989

Doppler ophthalmic blood pressure measurement in the hemodynamic evaluation of occlusive carotid artery disease.

In 102 patients with angiographically proven occlusive carotid artery disease of 60-100% diameter reduction, Doppler ophthalmic artery pressure and blood flow direction were recorded by the recently developed ophthalmomanometry-Doppler technique. Among these 102 patients, 50 presented with complete carotid artery occlusions and 52 with carotid artery diameter stenoses of greater than or equal to 60%. Mean +/- SD Doppler ophthalmic artery pressure was 69 +/- 15 mm Hg ipsilateral to the occlusion and 86 +/- 18 mm Hg ipsilateral to a stenosis of the carotid artery (p less than 0.001). The mean +/- SD Doppler ophthalmic pressure index (ratio of the ophthalmic artery to systemic blood pressure) was lower ipsilateral to the occlusion (0.46 +/- 0.08) than ipsilateral to a carotid artery stenosis (0.54 +/- 0.08; p less than 0.001); in both, the index was clearly diminished compared with normal values (0.68 +/- 0.04; p less than 0.001). It is concluded that the intracranial hemodynamic consequences in the patients with occlusion are on average more profound than in the patients with stenosis. In carotid artery occlusions, the mean +/- SD ipsilateral ophthalmic pressure index was 0.46 +/- 0.06 for antegrade and 0.46 +/- 0.09 for retrograde ophthalmic artery blood flow. In carotid artery stenoses, the mean +/- SD ipsilateral ophthalmic pressure index was 0.55 +/- 0.07 for antegrade and 0.48 +/- 0.06 for retrograde ophthalmic artery blood flow (p less than 0.01). These results indicate that in carotid stenoses the collateral capacity of the ophthalmic artery is insufficient compared with intracranial collaterals, while in carotid occlusions the blood flow direction in the ophthalmic artery does not predict intracranial hemodynamic compensation.

Adult↗
PubMed1989

[Duplex ultrasound studies of the deep femoral artery].

In case of occlusion of the superficial femoral artery (SFA), the deep femoral artery (DFA) supplies the entire lower extremity. Not infrequently, the SFA occlusion is associated with stenosis of the origin of the DFA. The angiographic study of the origin of DFA is often unsatisfactory. The purpose of the present study was to develop objective criteria for the diagnosis of the DFA origin stenosis by duplex scanning. In 60 patients, we examined 75 femoral bifurcations by duplex scanning and compared them with the independently performed angiography. Group 1 (n = 20 DFA origins) consisted of 10 normal individuals. Group 2 (n = 30 DFA origins) consisted of 25 patients with angiographically proven SFA occlusion and normal DFA. Group 3 (n = 25 DFA origins) consisted of 25 patients with angiographically proven SFA occlusion and DFA orifice stenosis. We measured the maximal systolic and mean flow velocity in the orifice of the DFA at rest and during the maximal hyperemia following 3 min of ischemia of the lower leg. At rest, the maximal flow velocity in groups 1-3 was 60 +/- 15, 142 +/- 44, and 255 +/- 60 cm/s (p less than 0.01) and the mean flow velocity was 8 +/- 6, 32 +/- 9, and 96 +/- 42 cm/s (p less than 0.01). During hyperemia, the maximal and mean flow velocity for groups 1-3 was 59 +/- 15, 155 +/- 42, and 286 +/- 82 cm/s (p less than 0.01) and 8 +/- 5, 55 +/- 19, and 144 +/- 51 cm/s (p less than 0.01), respectively. An origin stenosis of the DFA is highly probable when at rest the mean and maximal velocity in the proximal DFA exceed 50 cm/s and 180 cm/s, respectively. These results show that duplex scanning is able to detect safely DFA origin stenosis. The increase in postischemic DFA flow velocity when SFA occlusion is present, helps to evaluate total flow resistance of the deep-outflow channels (run-off) thereby being useful in planning appropriate therapy.

Adult↗
PubMed1988

The effect of fluoride on bone histology in postmenopausal osteoporosis depends on adequate fluoride absorption and retention.

Forty-one women with idiopathic postmenopausal osteoporosis have been followed for 2 years after initiation of sodium fluoride at 40-50 mg/day, given together with a daily calcium supplement of 1 gram and vitamin D2, at 50,000 IU weekly. Histological and histomorphometric analyses were done on bone biopsies taken prior to and after 1 year of treatment (mean 1.25 +/- 0.35 years). Thirty patients (74%) developed the histological fluoride effect of hyperosteoidosis, while the remaining 11 patients (26%) had no change from pretreatment biopsies. Hyperosteoidosis was based on increased values for osteoid volume and/or thickened osteoid with greater than 3 lamellar bands. Based on previously reported findings, this histological evidence of hypersoteoidosis within 12-18 months of initiation of therapy provides a useful predictor of ultimate satisfactory fluoride response in terms of bone mineral accretion. No increases in bone mass (measured by neutron activation analysis) were observed at the time of the posttreatment biopsy but, according to this previous work, increases are anticipated over a further 2-3 years of treatment. Factors affecting the development of hyperosteoidosis were analyzed. Hyperosteoidosis was associated with a significantly higher dose of sodium fluoride and a significantly higher level of bone fluoride retention but without significant increase in fasting serum fluoride. Results suggest that fluoride retention depends not only on fluoride dose but also on body size, renal function, and intestinal absorptions of calcium and fluoride. There were no differences in the initial investigations between patients with and without hyperosteoidosis, with respect to age, years of postmenopause, estrogen use, initial biochemistry, or initial bone histology.(ABSTRACT TRUNCATED AT 250 WORDS)

Biopsy↗
PubMed1987

Experiences with a new procedure for the measurement of the ophthalmic artery pressure: ophthalmomanometry-Doppler.

A novel, noninvasive method to determine simultaneously ophthalmic artery pressure (OAP) and flow direction, called ophthalmomanometry-Doppler, is presented. This technique uses a device consisting of a chamber with an apperture hermetically adaptable to the orbital borders. The chamber is equipped with a Doppler probe and an arrival pipe for compressed air connected to a manometer. The OAP measurement procedure consists of applying a pressure in the chamber while the Doppler probe detects periorbital Doppler signals. The systolic OAP corresponds to the Doppler signal disappearance during chamber pressure increase. Studies performed on normal subjects with direct recording of the internal carotid artery pressure (ICP) and indirect determination of the brachial artery pressure (BAP) demonstrated that OAP values assessed by the ophthalmomanometry-Doppler device were highly correlated with simultaneous ipsilateral intra-arterial systolic ICP measurements (r = 0.95, n = 10) and with simultaneous recordings of the BAP (r = 0.85, n = 40). The ophthalmic pressure index (OAP/ICP and OAP/BAP ratio, respectively) ranged from 0.60-0.77 with a mean (+/- SD) of 0.68 (+/- 0.04) in the 50 normal subjects. Preliminary clinical trials show diminished OAP/BAP ratios in patients with occlusive carotid disease ipsilateral to hemodynamically significant lesions. The values obtained on these normal subjects provide baseline data for further investigation of pathologic conditions. This new procedure is simple, convenient, rapid, and safe and provides reproducible information on both OAP and flow parameters, which are important indices in the evaluation of severe carotid artery disease.

Adult↗