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Biomedical subjects

W Rutishauser

Publications and source records attributed to W Rutishauser.

At least 19 recordsLinked to original sources
PubMed1992

[Regional coronary flow in ml/min measured with conventional coronarography].

We have developed a new method of measuring absolute coronary blood flow (CBF) in all major branches of the coronary circulation using computer analysis of conventional cineangiograms. A coronary cineangiogram is obtained in any biplane projections at 50 fps and digitized into a 512 x 512 x 8 matrix. The artery is reconstructed in 3D using the x-ray projection matrices calculated from a cube filmed in the same projections. All diameters along the artery are automatically determined. The arterial volume is calculated from the 3D reconstructed true arterial length and diameters. The absolute flow is obtained by dividing the arterial volume filled by contrast medium during the first cardiac cycle following the injection by the duration of that cycle. The method was validated in vivo by comparing LAD flow measured by angiography with great cardiac vein flow simultaneously measured by thermodilution. Ten patients were studied at baseline and during pacing-induced hyperemia at 100 and 120/min. Mean flow was 52.1 ml/min (range 28-93) by angiography and 51.5 ml/min (range 11-115; NS) by thermodilution. The two methods correlated well: r = 0.82, SE = 9.8 ml/min, n = 27, p less than 0.0001. Thus, absolute CBF can be measured by computer analysis of conventional biplane coronary cineangiograms.

Aged↗
PubMed1992

[Consequences of circadian variability for the treatment of ischemic heart disease].

The incidence of ischemic cardiac events is highest in the early morning hours (symptomatic and asymptomatic cardiac ischemia, myocardial infarction, and sudden death). Quantitatively, however, most of them occur during the rest of the day; therefore, an ideal therapy should be established in the early morning hours and be efficient all day long. We recommend that nitrates should be taken as early as possible after a dose-is-free interval during the night. Patients taking beta-blockers do not show a circadian rhythm of the incidence of ischemic cardiac events. Compliance can be improved with the never long-acting agents. Therapy should be tailored individually for each patient. It is not yet known whether calcium blockers influence the circadian rhythm. The efficacy of the never preparations is comparable to the older ones. Aspirin can be taken at any time of the day because of its long duration of action.

Angina Pectoris↗
PubMed1992

Morphometry versus densitometry--a comparison by use of casts of human coronary arteries.

Geometric and densitometric methods for quantitative coronary arteriography have generally been compared by use of phantoms simulating arteries with circular lumina ('Hole phantoms'). We have used more adequate phantoms obtained by casting disease-free and atheromatous human coronary arteries. The phantoms, filled with contrast medium, were imaged digitally (1024 x 1024 x 10 matrix) under experimental conditions simulating routine coronary angiography. The angiographic 'diameters' and the densitometric cross-sectional areas of 59 marked lumina were determined in single plane and orthogonal biplane raw images. Geometric calibration was performed by help of a 7F coronary catheter. For the densitometric calibration, we used a 'hole phantom' attached to the image intensifier. The obtained luminal areas were compared to their true values determined previously by planimetry. The mean absolute error of single plane cross-sections obtained geometrically was 1.53 mm2. Biplane imaging reduced it by a factor 2.4 to 0.64 mm2. The corresponding mean absolute errors for densitometry were 0.56 mm2 and 0.51 mm2. Single plane 'diameter' measurements appear thus of very limited value for hemodynamic conclusions. In contrast, biplane geometric quantification was not markedly inferior to single plane and biplane densitometry.

Absorptiometry, Photon↗
PubMed1992

3D-reconstruction of coronary arteries in view of flow measurement.

An angiographic method for measurement of absolute coronary blood flow in patients was developed. It is based on 3D-reconstruction of the left or right coronary tree from digitized biplane coronary cineangiograms. The apparatus is presently composed of a 35 mm cinefilm projector with a video camera and a 512 x 512 x 8 bits image array processor controlled by a VAX-11/750 computer. First, the parameters of the two angiographic projections are determined in form of two 4 x 3 matrices from a pair of cineframes showing a 4 cm cube bearing markers. The cube is filmed after the coronary injection, with unchanged geometric configuration. The coronary arteries of interest are then 3D-reconstructed from a pair of cineframes showing them fully opacified. This allows to compute the intravascular volumes needed for flow determination. In vitro experiments showed that the obtained volume are reasonably accurate. For the measurement of coronary flow, the concentration of contrast medium along the involved arteries is computed (in arbitrary units) from two cineframes taken one (or two) cardiac cycle after onset of the injection. This yields a 'concentration-distance' curve per artery. The volume of fluid (contrast medium mixed with blood) which flows into the arteries during this (or these two) cardiac cycle is determined by applying a concentration threshold to the obtained concentration-distance curves. Measurements performed on a constant flow model were satisfying. Preliminary measurements in 12 patients showed that flow values obtained angiographically into the left anterior descending coronary artery correlate well with the values measured simultaneously by thermodilution in the great cardiac vein (Qangio = 0.83 x Qthermo + 16.1 ml, r = 0.87, n = 29).

Cineradiography↗
PubMed1992

Abnormal left ventricular filling pattern in patients with single vessel coronary artery disease: effect of angioplasty.

To study the effect of coronary angioplasty (PTCA) on left ventricular (LV) diastolic filling, mitral Doppler flow tracings of 15 patients with isolated stenosis of the left anterior descending coronary artery (LAD) and normal systolic LV function were recorded before PTCA as well as 24 h and 3 months after successful PTCA. Compared to control subjects, patients with LAD stenosis exhibited an abnormal LV filling velocity pattern before PTCA. The day following PTCA, the ratios of the early peak diastolic velocity to the peak late diastolic velocity and of the time velocity integral of the early diastolic filling phase to the time velocity integral of the late diastolic filling phase were unchanged. Despite the absence of clinical evidence of restenosis, LV filling remained abnormal 3 months after PTCA. The results suggest that abnormalities of the LV filling velocity in patients with isolated LAD stenosis and normal systolic function may persist as long as 3 months after PTCA.

Angioplasty, Balloon, Coronary↗
PubMed1991

Spatial reconstruction of coronary arteries from angiographic images.

A method for 3D reconstruction of coronary arteries from two angiographic projection views is presented (cinefilm 35 mm, 50 images/s). The geometric information defining the two projections is secured by filming a cube bearing 15 steel markers in the approximate location of the heart. For 3D reconstruction, a pair of images of the cube and two simultaneous images of the coronary tree are digitized on a computer assisted system. Two matrices describing the two projections are obtained from the 15 x 2 x 2 image coordinates of the cube markers. Next, the operator draws with a mouse the approximate centre lines of the coronary arteries to be 3D reconstructed. The program then determines the centre lines and the edges of the vessels in the two images accurately. The 3D centre lines are reconstructed and the true local vessel diameters determined. Intravascular volumes are obtained by summation of elementary volumes. The reconstructed arteries are visualized on a colour TV monitor. Measurements on various phantoms have shown that lengths of a few centimetres can be measured with typically 2% error. The accuracy of volume determination was somewhat less due to the inaccuracy of lumen determination. For real coronary arteries the volume error is estimated to be about 15% because of the poorer image quality.

Angiography↗
PubMed1990

Long-term results of successful and failed angioplasty for chronic total coronary arterial occlusion.

The results over a mean period of 2 years of successful percutaneous transluminal coronary angioplasty (PTCA) in 100 consecutive patients with chronic total coronary occlusion were compared with those in 100 consecutive patients whose PTCA was unsuccessful. The groups were comparable in terms of gender, age and arteries attempted. A control angiography in the group with successful PTCA was performed in 62 patients and showed a restenosis in 28 (45%). Repeat PTCA was performed in 21 versus 1 patient with failed PTCA (p less than 0.0001). At follow-up, in the group with successful PTCA, there were 57 symptom-free patients versus 26 patients in the group with failed PTCA (p less than 0.0001). Coronary artery bypass surgery was performed in 7 versus 37 patients (p less than 0.0001), and there were 5 versus 3 deaths (difference not significant), respectively. In the group with successful PTCA, 27 of 82 patients (33%) had positive stress test results, compared with 49 of 85 patients (58%) in the group with unsuccessful PTCA (p less than 0.001). The double product (beats/min x mm Hg/100) in patients with successful PTCA improved from 247 +/- 57 before PTCA to 277 +/- 61 (p less than 0.001) at follow-up, whereas it did not significantly change in patients with failed PTCA. The work load (W) in patients with successful PTCA improved from 95 +/- 34 before PTCA to 124 +/- 40 at follow-up (p less than 0.001). In patients with failed PTCA, work load improved less significantly, from 98 +/- 37 before PTCA to 108 +/- 34 at follow-up (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Angioplasty, Balloon, Coronary↗
PubMed1990

[Acute myocardial infarction and thrombolysis: analysis of the delay in arrival at the hospital].

Since the duration of precordial pain plays a key role in the indication for thrombolytic treatment in acute myocardial infarction, a retrospective study was made of the last 200 infarctions at Monthey Hospital with particular reference to the factors influencing this duration (distance, type of transport, prior intervention by a physician, loss of time in hospital). These factors were compared with other studies, and ways of influencing the time factor are proposed.

Aged↗
PubMed1990

Nonselective preoperative digital subtraction angiography of internal mammary arteries.

In preparation for coronary bypass surgery, digital subtraction angiography (DSA) was used to assess the caliber of the left and right internal mammary arteries and to exclude stenoses of their feeding arteries. In 100 patients (86 males, mean age 56 +/- 9 years) DSA was performed with a Siemens Digitron 2 device. A frontal projection was used in 18 patients, and a 10-20 degree right anterior oblique projection was used in 82 patients. The flow was 10 to 25 ml/sec; 20 ml was injected in 45 patients, 30 ml in 41, 40 ml in 5, 50 ml in 8, and 60 ml in 1 patient. Judged on the proximal third, visualization of the left and the right internal mammary artery was good in 80 and 72, fair in 17 and 20, and bad in 3 and 8 arteries, respectively. The diameter (mm) was 2.7 +/- 0.4 (range 1.8-3.4) and 2.7 +/- 0.3 (range 2.0-3.5), and visible length (cm) was 8 +/- 5 (range 1-24) and 9 +/- 4 (range 2-22) for the two arteries, respectively. The 10-20 degree right anterior oblique view separated the left internal mammary artery better from the descending aorta than the frontal view. In more pronounced right anterior oblique views the ascending aorta interfered with the right internal mammary artery. The quality was not different with 20 ml or 30 ml injections. The feeding arteries could not be assessed in 4 patients. One left subclavian artery was found occluded at the orifice. Incidentally, 2 distal right subclavian stenoses and 2 carotid stenoses were detected.(ABSTRACT TRUNCATED AT 250 WORDS)

Angiography, Digital Subtraction↗
PubMed1990

Congenital intrathoracic left ventricular diverticulum in an adult.

A 53-year-old woman without any risk factors for coronary artery disease was found to have a congenital intrathoracic left ventricular diverticulum with a narrow long connection to the left ventricular cavity. Coronary angiography revealed normal coronary arteries. The diverticulum was resected and showed three normal cardiac layers. This is an extremely rare finding in the adult population.

Diagnosis, Differential↗
PubMed1989

Doppler assessment of left ventricular diastolic filling during brief coronary occlusion.

To assess left ventricular diastolic filling in patients with single-vessel coronary artery disease, Doppler-derived transmitral velocity was studied in 22 normal subjects and in 15 patients with isolated proximal stenosis of the left anterior descending coronary artery (LAD) and normal systolic function of the left ventricle. Transmitral velocity was recorded before and after balloon inflation during coronary angioplasty. At baseline the transmitral velocity pattern in patients with LAD stenosis differed from that of normal subjects with a significant (p at least less than 0.05) decrease in the early diastolic filling phase (E area 0.094 +/- 0.022 m in normal subjects vs 0.078 +/- 0.008 m in patients) and an increase in the late diastolic filling phase (A area 0.034 +/- 0.007 m vs 0.042 +/- 0.008 m). Correspondingly the ratio E area/A area decreased (2.7 +/- 0.51 vs 1.9 +/- 0.4) and the ratio A area/total area increased (0.28 +/- 0.04 vs 0.35 +/- 0.05). During coronary occlusion the E area and the ratio E area/A area decreased further, whereas the A area and the ratio A area/total area increased. The results suggest that patients with single-vessel disease and normal systolic function often exhibit an altered pattern of transmitral velocity even in the absence of overt ischemia, and that during acute regional ischemia early diastolic filling is further compromised with compensatory enhancement of the late diastolic filling phase.

Adult↗
PubMed1989

Morphometric versus densitometric assessment of coronary vasomotor tone--an overview.

The main advantage of the morphometric approach is that the spatial orientation of the vessel with respect to the image intensifier is not very important. Its most severe limitations are that reasonable accuracy can only be obtained with circular lumina, and that accuracy decreases rapidly with the vessel diameter. The densitometric approach is much less dependent on the shape of the lumen and on the correct identification of the vessel wall in the image. A further essential advantage is that one measures directly the cross-sectional area of the vessel instead of a 'diameter' of low haemodynamic relevance. Severe requirements must however be met if the potential accuracy of densitometry is to be fully exploited. The morphometric approach seems thus preferable for absolute or relative diameter measurements on intact vessels, while densitometry is superior in case of irregular or small lumina. Morphometric calibration using the injection catheter can induce non-negligible errors in both approaches. Grid calibration is probably more accurate, but also more tedious. In the densitometric approach, '3D-calibration' by help of a cube of known size allows also determination of the spatial orientation of the vessel in space. This solution requires however biplane imaging.

Angiography, Digital Subtraction↗
PubMed1988

Clinical experience with the Monorail balloon catheter for coronary angioplasty.

The Monorail balloon catheter is distinctly different from other current balloon catheters: the guidewire passes through the balloon itself, exits the catheter proximal to the balloon, and runs alongside its small shaft (3 French) through the guiding catheter. Monorail coronary angioplasty was attempted in 61 patients on 73 lesions with balloons from 2.0 to 3.7 mm. Angiographic success was obtained in 66 lesions (90%). For 15 lesions, balloon exchanges were needed. In three lesions, the Monorail balloon failed to cross the lesion, while a standard balloon succeeded; two lesions could not be crossed with any balloon. Vessel occlusion occurred in four patients: two had emergency surgery without infarct (one died suddenly 4 days later and one had a stroke 1 day later), one was recanalized with a standard balloon, and one had a myocardial infarct. Continuous infusion of urokinase was used until patient 3 in whom problems with the delivery system led to cardiocerebral air embolization (with complete recovery). No thrombotic complications were observed in the subsequent 58 patients with only a bolus of 10,000 U of heparin. The Monorail balloon facilitates contrast injections and balloon exchanges but appears more difficult to pass through tight lesions. Omission of the previously recommended infusion with a thrombolytic agent proved safe.

Adult↗
PubMed1988

Silent ischemia: a relevant problem in patients with coronary artery disease?

Awareness of silent myocardial ischemia has greatly increased during the last few years in the medical community. Methods for its detection include exercise testing, Holter monitoring, and, more specifically, Thallium-201 scintigraphy, 2D-echocardiography, and multigated radionuclide ventriculography with phase analysis, all during rest and exercise. Cohn's classification of silent ischemia has proven very useful in highlighting the magnitude of the problem. It can be estimated that about 2% to 4% of apparently healthy middle aged males in industrialized European countries are prone to asymptomatic ischemic episodes. Prognosis of silent myocardial ischemia has been evaluated in prospective and retrospective studies. Most authors come to the conclusion that ischemia is the key finding, whether painful of asymptomatic. Even present understanding of pain perception from the ischemic myocardium is incomplete; the high prevalence and the relation with myocardial infarction and sudden cardiac death make silent myocardial ischemia one of today's most relevant problems.

Coronary Disease↗
PubMed1988

Assessment of regional coronary flow reserve by digital angiography in patients with coronary artery disease.

Digital angiography provides a convenient means to quantify the progression of a contrast medium bolus injected into a coronary artery throughout the myocardium, which in turn yields information on myocardial perfusion. Sixteen patients presenting a single critical proximal stenosis (estimated diameter reduction greater than 80%) on either the left anterior descending coronary artery (LAD) or the left circumflex coronary artery (LCX) were studied. First, 12 consecutive end-diastolic images of an ECG-triggered intracoronary injection of 4 ml of iopamidol were acquired on 60 degree left anterior oblique projection under basal conditions. This was repeated 30 s after intracoronary injection of 12 mg of papaverine. For each image sequence, a densogram was computed in each pixel by fitting a curve through its 12 consecutive intensity values. The 'time of maximal pixel opacification' (TMAX) and the 'mean ascending time' (TMAT), expressed in cardiac cycles, were determined from each curve. Two myocardial regions of interest (ROI) were defined for each patient, one in the perfusion bed of the LAD, the other in the bed of the LCX. The mean values of TMAX and TMAT in each ROI were computed, at rest and during hyperemia. At rest, the mean values of TMAX and TMAT obtained from the ROI associated to the stenosis artery were not significantly different from the values obtained in the ROI associated with the intact artery. During hyperemia, a significant decrease of the mean TMAX and TMAT was observed in the normally perfused regions (p less than 0.001). The rest to hyperemia ratios of both TMAX and TMAT mean values were considered to be indices of coronary flow reserve.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗