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Biomedical subjects

N Schad

Publications and source records attributed to N Schad.

At least 55 records · Page 3Linked to original sources
PubMed1982

Regional left ventricular function in the three main coronary artery territories at rest and during exercise.

Twenty consecutive patients (mean age 51.6 years) with persistent severe angina pectoris underwent aorto-coronary bypass surgery receiving an overall of 60 anastomosis. On an average, 9.4 +/- 1.5 months p.o. first pass radionuclide ventriculograms (18 to 24 mCi 99m Technetium-Pertechnetate i.v.) were performed at rest and after exercise. Besides measurement of global ejection fraction (GEF), regional ejection fraction (REF) was assessed employing for the first time a new technique: each RAO-view of p.o. radionuclide left ventriculogram was subdivided into three regions according to supply of the three main coronary arteries and their branches as visualized on pre-operative coronary angiogram. GEF improved after maximum exercise in 13 cases by 8.1% points (from 50.4 to 58.5%), remained unchanged three times and decreased four times by 7.1 points (from 51.6 to 44.5%; all changes p less than 0.05). In completely revascularized regions (n = 35) REF improved 24 times by 9.7 points (from 51.1 to 60.8%), did not differ from rest REF six times and decreased in three case by 7.3 points (from 48.6 to 41.3%; all changes p less than 0.05). completely revascularized regions responded to exercise like normally perfused areas (increase 7.8 points (from 50.6 to 58.4%; n = 7; p less than 0.05). REF deteriorated in incompletely revascularized regions (n = 9) six times by 12.8 points (from 58.0 to 45.2%), remained unchanged twice and improved once by 4.5 points. Total group's REF decreased by 7.3 points (from 56.8 to 49.5%; p less than 0.05). Exercise REF of incompletely revascularized regions was highly significant inferior to that of completely revascularized regions (49.5 to 58.4%; p less than 0.01). GEF is a weighted balanced of the three regional ejection fractions. The most important parameter is REF of LAD territory.

Adult↗
PubMed1982

Valve replacement for chronic mitral insufficiency; long-term follow up using technetium pertechnetate scintigraphy.

Technetium Pertechnetate Scintigraphy was performed in 12 patients (9 men and 3 women, average age 48 +/- 13 years) on an average 19.8 +/- 11 months after valve replacement for chronic mitral insufficiency. Preoperative conventional ventriculography had revealed increased enddiastolic and endsystolic volumes (230.9 +/- 66 resp. 73.5 +/- 26 ml). 59.4 +/- 9% of the stroke volume (157.5 +/- 47 ml) regurgitated into the left atrium. Ejection-fraction (67.7 +/- 6%) was normal in all cases. Postoperative first pass technique was employed using a fast multicrystal camera (Baird Atomic, system 77). Volumes were assessed measuring normalized total count rate (count integral of the left ventricle divided by the maximum count density). 19.8 +/- 11 months after valve replacement enddiastolic and endsystolic volumes revealed normal at rest (121.8 +/- 38 resp. 52.8 +/- 35 ml) and after maximum exercise (122.0 +/- 29 resp. 37.6 +/- 22 ml). Ejection fraction responded physiologically to exercise by rising from 57.7 +/- 12 to 69.7 +/- 10%.

Adult↗
PubMed1982

Scintigraphic measurement of left-ventricular volumes from the count-density distribution.

An experimental model was developed using ellipsoidal balloons of different volumes to derive an empirical formula linking the "normalized" total count rates on gamma-camera images to volume. The normalized total count rate (NTC) is defined as the total count rate divided by the maximum count density. If an object is at a constant distance from the collimator, the NTC is found to be a linear function of volume. This formula was then applied to calculate left-ventricular end-diastolic volume from scintigraphic images obtained by radionuclide ventriculography in 71 consecutive patients. The distance from the left ventricle to the collimator was estimated from the patient's height and weight. The volumes calculated by the radionuclide method were compared with angiographic volumes obtained at cardiac catheterization, and good correlation was found (r = 0.95).

Cardiac Output↗
PubMed1981

[Coronary artery calcification fluoroscopy. A report on procedure of detection and clinical significance (author's transl)].

The methodology of cardiac fluoroscopy and the clinical significance of the coronary artery calcification are judged on the basis of a study on the group of 396 normal persons, 22.72% of whom resulted to suffer from it, while the report says that 46.80% of a group of 94 patients with coronary artery disease suffer from the same. In normal people the coronary artery calcification has practically the same frequency in both sexes and increases with the age, while in patients with coronary artery diseases there is a higher frequency in the fifth decade and in male sex. The discovery of calcification in all cases always shows an advanced coronary atherosclerosis. In the patients with clinical coronary artery diseases, there are also evidence of significative obstructive lesion. The fluoroscopy of the heart is the most powerful tool for the diagnosis of coronary artery calcification in vivo, it is easy to be used and gives diagnostic information of great value in the study of a coronary artery disease.

Adult↗
PubMed1980

Assessment of regional blood flow by intravenous injection of 99m-technetium-pertechnetate.

A general method for computation of regional blood flow from time-activity curves obtained after intravenous injection of 99m-TC pertechnetate is presented. The method is based on the well-known principle of Meier and Zierler, but, it also considers the dispersion of an intravenously injected activity-bolus as well as the recirculation of the nondiffusible tracer. The problems arising from the use of a nondiffusible indicator concerning the partition coefficient lambda are discussed. This method of blood flow determination is adopted for measurements of cerebral blood flow and some first results are discussed.

Adult↗
PubMed1980

[Radiological diagnosis of peripheral pulmonary stenosis (author's transl)].

Peripheral pulmonary stenosis is frequently associated with congenital heart disease and seen in childhood. It is rather rarely discovered in adult patients. In adults, however, it is detected as an isolated congenital deformity or as part of generalized congenital cardiovascular disease and may also be caused by collagen disease. The chest x-ray and nuclear scan demonstrate the condition, but pulmonary angiography is essential for positive confirmation.

Adult↗
PubMed1980

[Non-invasive evaluation of regional function of the left ventricle. Initial tracer passage (author's transl)].

Assessment of regional left ventricular function with first pass angiocardiography in the RAO view almost entirely depends on high image statistics, accurate border definition and background subtraction, as well as an analysis of so called functional images which regionally measure and illustrate functional change during heart action, such as regional ejection fraction images, regional ejection rate images and mean transit time images. During first bolus transit the multicrystal camera gives an average of 300,000 cts/sec (360 patients) allowing precise border definition because of steepness of count changes at the LV-border. A varying background adjacent to each border point and also over the LV is subtracted. Measurements of segmental hemiaxis shortening and of zonal ejection fractions in the three zones supplied by the major coronary arteries have been performed. Clinical applications comprise examinations at rest, peak exercise, after nitroglycerin administration and after bypass graft surgery (total 2400 studies). Wall motion measured by means of hemiaxis shortening (210 segments) showed good correlation with angiocardiography in 91% of segments with normokinesis, in 90% asynergic and 88% of hypokinetic segments. Functional images corrected false negative and false positive wall motion measurements. In another 44 patients after myocardial infarction, there was (after NTG-administration) a significant increase in hemiaxis shortening in asynergic segment, but not in dyskinesias. Exercise studies in 60 patients with wall motion disorders showed a significantly higher increase in global ejection fraction in patients with resting EF-values under 58% than above that value. If ejection fraction tended to increase more than 5 points, wall motion tended to improve at exercise and viceversa. Zonal ejection fractions after bypass surgery showed an average increase of 6.4 points (14%) if complete vascularization was performed, but no zonal increase or decrease when vascularization was incomplete or the zone included a previous myocardial infarction (scar formation).

Coronary Artery Bypass↗
PubMed1979

[Targeted heart fluoroscopy in radiologic and internistic practice].

Fluoroscopic examination of the heart requires a special technique if it is to provide useful diagnostic information. Information can be obtained regarding coronary calcifications, slight enlargement of a heart chamber or great vessel, localization and extension of abnormal contours within the heart shadow, pulsatory phenomena at the heart border or the great vessels, and functional changes of lung structures during respiration. This information may be decisive for the further evaluation or treatment of the patient.

Cardiomegaly↗
PubMed1978

Image analysis of the heart action recorded with a high speed multicrystal gamma camera.

The use of a high speed scintillation gamma camera for recording and an adequate bolus injection technique during first pass of a radionuclide tracer provides significant information about the function of the heart chambers. The computer-stored information can be processed to get easy interpretable images and parameters for detailed diagnosis. With special procedures the statistical noise of the zones of the images with low count rates can be suppressed, allowing use of smaller quantities of radionuclide, thereby reducing radiation for the patient.

Angiography↗