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Biomedical subjects

N Schad

Publications and source records attributed to N Schad.

At least 37 records · Page 2Linked to original sources
PubMed1986

[Improved regional myocardial function after aortocoronary bypass surgery noninvasive studies using the first-pass technic].

50 patients after coronary artery bypass grafting were matched with 50 not-operated patients. After a follow-up period of four years they were investigated by first pass radionuclide angiography. Revascularized myocardial areas showed significantly higher regional ejection fraction during exercise and in territories with prior myocardial infarction. The results proved the hemodynamic benefits of coronary artery bypass grafting even in territories with poor myocardial function.

Angina Pectoris↗
PubMed1986

Non invasive assessment of regional diastolic left ventricular function with first pass radionuclide functional imaging in ischaemic heart disease.

Functional images of regional distribution of rapid filling (RF) rates have been developed and applied at rest and on exercise for regional analysis of 301 coronary artery territories (103 compromised by coronary narrowings, 198 normal). The observed time-interval of RF averaged 209 ms at rest (range 200 to 280) and 172 ms on exercise (range 125 to 200 ms). Normal RF is directed to the apex, and it is deviated from territories with reduced compliance to normal territories. Sensitivity in detection and localization of territories compromised by coronary narrowings exceeds 90% at rest for the anterior and infero-posterior wall and is higher than that obtained from systolic functional images. Specificity amounts also to over 90% and is much higher than that observed with systolic functional images. During RF, moderate to severe loss in compliance results in initial regional paradoxical inward motion in 40 to 45% of anterior or postero-inferior segments eventually accompanied by significant inward displacement of blood. Thus, with functional imaging of regional RF rates one can establish dysfunction and functional significance of coronary narrowings.

Adult↗
PubMed1986

What is the most appropriate stimulation mode in patients with sinus node dysfunction?

Sinus node disease (SND) has caused many controversies about the appropriate stimulation mode. We compared the advantages and disadvantages of VVI, AAI, DDD, and DDI mode. In an additional study, left ventricular function at rest (R) and during exercise (E) was investigated in dual chamber and ventricular stimulation mode with a stimulation rate of 70 ppm (R) and 110 ppm (E). A total of 223 patients (pts) was investigated (67 AAI, 87 VVI, 69 DDI). Hemodynamic disadvantages in VVI mode resulted in a 55% actuarial incidence of atrial fibrillation after five years. In AAI mode, we found another 25% complication rate due to impaired AV conduction (n = 9) or a bradyarrhythmia (n = 6) with slow ventricular response. DDI mode implies the possibility of sustaining a pacemaker mediated tachycardia. Single ventricular stimulation with a high stimulation rate (110 ppm) under E showed a worse left ventricular performance as compared to dual chamber stimulation. DDI mode shows none of the aforementioned disadvantages. To sum it up: Until a dual chamber rate responsive pacemaker becomes available, the DDI mode represents the best stimulation mode for patients with a SND.

Atrial Fibrillation↗
PubMed1986

[Value of nuclear magnetic resonance tomography and first-pass radionuclide ventriculography in cardiomyopathies].

12 patients with cardiomyopathy were examined by MRT and first pass angiocardiography. MRT provides detailed images of cardiac anatomy and abnormalities without using any contrast medium. The first pass method is an excellent complement to MRT. The functional imaging describes regional wall motion of myocardium exactly. Both non-invasive methods are useful for the diagnosis of cardiomyopathy.

Cardiac Output↗
PubMed1986

[Radioisotopes].

Explore the source record for details and available documents.

Blood Flow Velocity↗
PubMed1985

Late (11 to 19 years) assessment of hemodynamic and prosthetic valve function in patients with Starr Edwards ball valves: a non-invasive study utilizing 99m-technetium pertechnetate scintigraphy.

This is an account of 2 groups of 10 patients each who received Starr Edwards ball valves in either the mitral (M) or aortic (A) position on average 14.7 +/- 3 or 14.9 +/- 2.4 years ago, respectively. Non-invasive scintigraphic studies were performed using the first pass of 18 to 20 mCi 99 m-Technetium Pertechnetate. Enddiastolic and endsystolic volumes were found elevated at rest: (M) EDV 135 +/- 50 ml, ESV 63 +/- 30 ml; (A) EDV 163 +/- 41 ml, ESV 69 +/- 25 ml. The response to maximum exercise--during which the heart rate increased from 85 +/- 23 min-1 to 133 +/- 33 min-1--was abnormal, since none of the volumes changed significantly. During exercise, therefore, the increase of the cardiac output was totally heart rate dependent: (M) 6.1 +/- 2.3 to 9.3 +/- 2.3 l/min; (A) 7.0 +/- 1.9 to 10.9 +/- 3.1 l/min. The dynamics of the rapid diastolic filling rate of the left ventricle (RFR) and the mean pulmonary transit time (MTT) served as functional parameters of the Starr Edwards ball valves in the mitral position. The rapid filling rate increased from 205 +/- 98 to 321 +/- 58 ml/sec, whereas MTT decreased from 7.4 +/- 1.4 to 5.4 +/- 2.1 sec. In patients with aortic valve replacement the left ventricular ejection rate was assessed, it rose from 233 +/- 80 to 459 +/- 232 ml/sec. The significant changes of the parameters proved that the Starr Edwards ball valve mechanism functions satisfactorily 11 to 19 years post-operatively.

Aortic Valve Insufficiency↗
PubMed1984

[Noninvasive first-pass study of the heart with the short-lived radionuclide gold 195m].

The new shortlived radionuclide Aurum 195 m (T1/2: 30.5 sec) has been used for 1,596 first-pass examinations of 792 patients. During first-pass the same maximum count rates of an average of 300,000 cts/sec and after background subtraction the same enddiastolic counts over the left ventricle averaging 10,000 cts/sec can be achieved as with the previously used Tc-99 m pertechnetate injections. The short half-life and fast regeneration of Au-195 m within 3 minutes allow repeated, subsequent injections with significant reduction in radiation exposure. Half of the studies were done at rest and exercise, one third in two oblique projections, RAO and LAO. Examinations in two projections improve the information facilitating the localization of ischemic or infarcted LV-regions particularly with respect of septal and/or lateral extension. Strictly lateral dysfunction may sometimes be only recognizable in the second LAO-projection. The RAO-view best discriminates the extension along the anterior and infero-posterior wall.

Evaluation Studies as Topic↗
PubMed1984

[Contribution to the study of angio-TC: timing of exposure and subsequent venous lavage].

The text reports the results of angio-CT examinations performed with single intravenous injections of small amounts of contrast medium and with the technique of timing of exposure and immediate venous flush with the use of a suitable injector (168 patients have been examined, in 157 of them the timing was correct while in 11 the timing was not adequate). The exposure is made after a certain period of time from the moment of the injection, corresponding to the number of heart cycles the contrast medium needs to reach the considered arterial district, during its first passage. The immediate venous flush allows one to use almost all the contrast medium to obtain the information and to take advantage of an almost compact bolus. The principal advantages of this technique are that a smaller amount of contrast medium and of radiation dose to the patient can be used.

Angiography↗
PubMed1984

[Radioisotope study (first pass) of left ventricular function in 2 oblique projections using gold-195m after myocardial infarction].

The radioisotope 195Aum because of its short halflife of 30 seconds and reduced radiation exposure allows routine first pass examinations in two oblique projections, i.e. right anterior and left anterior oblique. The value of the additional left anterior oblique projection has been examined in 30 patients after previous myocardial infarction by functional imaging in two oblique projections. The multicrystal gamma camera connected with a microprocessor and a contrast injector have been used. For assessment of left ventricular function the following functional images have been adopted: the regional ejection fractions (rEF), the regional ejection rates (rEJR) and the regional mean transit times (rMTT). The right anterior oblique view resulted diagnostic for miocardial infarction in 26 of 30 patients (86,6%). The left anterior oblique view was informative with respect of septal extension 17 times (58,6%), lateral extension 9 times (31%), septal and lateral extension 3 times. With regard of the different functional images the rMTT showed the severe dysfunction in the infarcted zones in all patients (100%), the rEJR in 29 patients (96,6%), the rEF in 28 cases (93,3%). In 4 cases dyskinesia was observed, twice in the left anterior oblique view and also twice in the right anterior oblique view. In patients with previous MI it is necessary to record the second left anterior oblique projection which can be done routinely by the use of 195Aum and first pass technique. On functional images, maximum information is obtained by the rMTT which visualizes the zones of severe dysfunction and its extension.

Aged↗
PubMed1983

[Global and regional left ventricular myocardial function following aorto-coronary multiple (5-, 6-, 7-) bypass. Non-invasive determination with technetium 99m-pertechnetate scintigraphy].

In 19 patients (mean age 55.3 years) with severe, diffuse coronary artery disease and stable angina pectoris, coronary artery bypass surgery was performed with an average of 5.36 anastomoses per patient. At 15.5 +/- 8 months postoperatively, radionuclide ventriculograms were obtained in the RAO projection (first-pass-technique) at rest and during maximal exercise by means of a multicrystal camera. To assess the effects of revascularization on the myocardial function, analysis was performed for global ejection fraction (GEF) as well as three regional ejection fraction (GEF) as well as three regional ejection fractions (REF) corresponding to the vascular beds of the three major coronary arteries. During exercise global ejection fraction increased in 13 patients (68.4%) an average of 9.5%-points from 51.5 to 61.0%, in one patient (5.2%) remained unchanged and in five patients (26.3%) decreased an average of 9.6% %-points from 62.6 to 53.0% (all changes p less than 0.05). The classification of the various myocardial regions was based on the preoperative coronary angiogram as well as intraoperative in-situ findings according to the status of the coronary vessels, the extent of revascularization and the presence of remote myocardial infarctions. Regions of group I had a significantly higher fraction of complete revascularizations, that is 79.9%. 61.1% of group-II-territories were incompletely revascularized. The weighted balance of the three regions supplied by the left anterior descending artery, the circumflex and the right coronary artery explains the postoperative response of the global ejection fraction to exercise.(ABSTRACT TRUNCATED AT 250 WORDS)

Angina Pectoris↗
PubMed1983

Parametric imaging of regional cerebral blood flow with the short-lived isotope 195mAu.

The use of the short-lived (30 s) isotope 195mAu in brain perfusion studies has been tested on 40 patients and 8 volunteers. The activity of the eluate from the 195mHg/195Au generator was high enough to give good image statistics of brain perfusion after a single bolus injection. The examinations can be repeated after 3 min giving the same quality and without significant background. The use of a low-energy photon peak at 68 keV (Au-K alpha) allows the imaging of brain perfusion in both lateral views with almost no look-through effect. With a modified height-over-area formula for the calculation of regional cerebral blood flow parametric images were obtained of high diagnostic value. The sensitivity and reproducibility of the method has been demonstrated by mental stimulation tests on eight volunteers: after optical stimulation a clear increase of blood flow could be shown in the visual cortex.

Brain↗