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Biomedical subjects

N Schad

Publications and source records attributed to N Schad.

At least 19 recordsLinked to original sources
PubMed1994

Detection of early systolic dysfunction in ischemia by sequential radionuclide imaging of ejection rates.

The effectiveness of sequential imaging of early regional left ventricular contraction in the detection of ischemic abnormalities was assessed in 47 patients (15 with previous infarction) with angiographically proven coronary artery disease, and 11 normal volunteers, undergoing first pass radionuclide angiography with a multielement gamma camera at rest and at peak exercise. Global left ventricular hemodynamic parameters, and functional images of regional ejection fraction and ejection rate were compared to 6 pairs of sequential rate images showing the decrease and the increase of regional left ventricular volume during a time-interval of 80-280 ms (at rest) and 50-175 ms (at stress) from end-diastole. Diagnostic accuracy of sequential images (67-91%) was higher than that of ejection rate image (71-72%), and of global hemodynamic parameters (33-60%), in the detection of coronary patients. Regional sensitivity of stress sequential increase and decrease image achieved 77% and 100%, respectively. During early systole sensitivity of stress sequential increase and decrease images approached 100% even at rest, subsequently decreasing because of normalizing contraction. Thus, the analysis of early systolic dysfunction provided by dynamic sequential functional images of ejection rates proved to be an effective diagnostic tool in the detection of myocardial ischemic dysfunction.

Adult↗
PubMed1993

Single-day combined evaluation of regional myocardial perfusion and function at rest and peak exercise with 99mTc-MIBI in patients with coronary artery disease.

99mTc-labeled methoxy-isobutyl-isonitrile (MIBI) allows a simultaneous radionuclide assessment of regional heart function and perfusion. In this study the effectiveness of functional and perfusional images obtained with 99mTc-MIBI in the detection of coronary stenoses was compared with that of their combination. We studied 197 patients who underwent coronary angiography and a single-day radionuclide protocol including first pass angiography (multicrystal gamma camera) and single photon emission computed tomography, by means of 2 injections of 99mTc-MIBI at rest and at peak exercise. Fifteen patients had < 50% stenoses, 50 had 1-vessel, 69 2-vessel and 63 3-vessel disease, for a total of 377 pathological major coronary vessels; 129 patients had previous myocardial infarction. Functional images, perfusional tomograms and their combination showed the same sensitivity (98%) and specificity (80%) in detecting coronary patients. Regional sensitivity and specificity of the combined analysis achieved 87% and 82%, respectively, vs. 94% (p < 0.005) and 60% (p < 0.001) of functional images, and 88% (p = N.S.) and 74% (p < 0.05) of perfusional tomograms. Thus, the combined analysis of regional functional and perfusional abnormalities increased significantly the specificity in the detection of coronary stenoses, in comparison with the separate evaluation of function and perfusion, achieving also a slightly higher diagnostic accuracy (85%, vs. 81% and 83%, respectively). The results confirm that a single-day protocol simultaneously assessing regional myocardial function and perfusion with 99mTc-MIBI represents a rapid and effective diagnostic method, that allows the physician to assess the presence and functional importance of coronary stenoses in less than 4 hours.

Coronary Disease↗
PubMed1992

The radiologic features of cardiac rotation: a pictorial essay.

Rotation of the heart results from enlargement of individual cardiac chambers and influences significantly the configuration of the cardiomediastinal silhouette. Left ventricular enlargement leads to dextrorotation. Conversely, right ventricular enlargement leads to levorotation. The axis of rotation is nearly vertical and extends from the top of the aortic arch through the anterior wall of the left atrium and the proximal interventricular septum. Pericardial defect, deformity of the thoracic skeleton, and lower lobe atelectasis can also lead to cardiac rotation. An understanding of this concept facilitates the interpretation of chest radiographs in patients with heart disease. The terms clockwise and counterclockwise rotation of the heart should be abandoned.

Cardiomegaly↗
PubMed1992

Metabolic cardiac imaging in severe coronary disease: assessment of viability with iodine-123-iodophenylpentadecanoic acid and multicrystal gamma camera, and correlation with biopsy.

Fifteen patients with coronary disease and resting left ventricular ejection fractions of less than or equal to 0.35 underwent resting metabolic cardiac imaging utilizing 1 mCi [123I]iodophenylpentadecanoic acid (IPPA) intravenously and a multicrystal gamma camera. Parametric images of regional rates of IPPA clearance and accumulation were generated. Forty-two vascular territories (22 infarcted) were evaluated by metabolic imaging as well as transmural myocardial biopsy. Despite resting akinesis or dyskinesis in 20/22 (91%) infarcted territories, 16/22 (73%) of these territories were metabolically viable. Transmural myocardial biopsies in all patients (43 sites, 42 vascular territories) during coronary bypass surgery confirmed IPPA results in 39/43 patients (91%). When compared to biopsy, scan sensitivity for viability was 33/36 (92%) with a specificity of 6/7 (86%). Eighty percent of bypassed, infarcted but IPPA viable segments demonstrated improved regional systolic wall motion postoperatively as assessed by exercise radionuclide angiography. We conclude resting IPPA imaging identifies viable myocardium, thereby providing a safe, cost-effective technique for myocardial viability assessment.

Biopsy↗
PubMed1991

ST/HR slope and improved exercise ECG detection of myocardial ischemia in patients with suspected coronary artery disease.

Predictive values of ST/HR slope and ST-segment displacement during symptom-limited exercise were determined in 85 patients who underwent coronary angiography for suspected coronary artery disease, using perfusional and functional radionuclide images with 99mTc-2-methoxy-isobutil-isonitrile as an index of stress-induced myocardial ischemia. ST/HR slope showed a better sensitivity than conventional stress-induced changes of ST-segment displacement (96% vs. 73%, respectively). In patients with clinical suspicion of coronary artery disease, the main result was the negative predictive value of ST/HR slope when compared with conventional ST-segment displacement (98% vs. 41%). ST/HR slope was unable to perfectly separate patients with different degrees of ischemia, however, subjects without scintigraphic signs of stress-induced ischemia and patients with ischemic impairment in three myocardial regions were correctly identified as distinct populations. In patients with a previous myocardial infarction, no difference was found between the two criteria and a wide overlap of ST/HR slope values was present. The authors conclude that ST/HR slope is useful to detect the rate of change in electric parameters during exercise and might therefore more adequately be used to separate normal from definitely abnormal responses to exercise.

Adult↗
PubMed1990

Regional rates of myocardial fatty acid metabolism: comparison with coronary angiography and ventriculography.

In 50 patients, 1 mCi 123I phenylpentadecanoic acid (IPPA) was injected at peak ergometric stress and 1500 frames were acquired (1 frame/s) with a high count rate gamma camera. Parametric images of rates of decrease and increase for different time intervals after stress were compared with coronary angiography and LV ventriculography, separately evaluating the 3 main coronary territories: 18/150 territories supplied by normal coronaries presented rather homogeneous regional clearing rates, whereas a gradual decrease in clearing rates towards the end of the territory (frequently with peripheral defects) was seen in all 87/150 territories with significant coronary narrowing. In local correspondence to clearing defects, initial IPPA accumulations could be observed with later onset of clearing between 10 and 25 min. 44/150 territories presented abnormal clearing rates, mostly with a patchy pattern, with normal coronary anatomy, but all except one had LV dysfunction and a clinical diagnosis of cardiomyopathy, diabetes mellitus or hypertensive disease. Twenty four of the 41 patients with CAD had, in correspondence to a prior myocardial infarction, minimum or missing metabolic activity frequently in circumscribed zones, partly separated by bridges of still viable tissue with preserved but reduced clearing rates.

Angiography↗
PubMed1990

The influence of rejection episodes on the development of coronary artery disease after heart transplantation.

Since 1981, 77 of 116 patients undergoing heart transplantation (HTx) have survived from 6 months to 8 years. Graft control involved a total of 871 endomyocardial biopsies (EMB) and 141 angiographies. Sixteen patients developed coronary artery disease (CAD) manifesting itself 7-60 months after HTx (20.7%). These patients (15 male, 1 female) experienced multiple rejection episodes (RE) and more than half suffered from hypercholesterolaemia and hypertension (n = 10). A mean rejection score (Billingham grading) of greater than 1 (mean = 1.6 +/- 1.1) was calculated in all patients with CAD at the time of angiography or autopsy. By contrast, the mean rejection score ranked less than 1 in patients with undetectable or resolved CAD (means = 0.4 +/- 0.38). This rate is not remarkably different from the rejection score in patients (n = 61) without CAD (mean = 0.2 +/- 0.4). The 8 patients alive (56 +/- 18 months) showed a low number of RE/year (mean = 1.1 +/- 0.4) compared with means = 1 +/- 0.9 in patients without CAD. Eight patients expired within a short period (mean = 31 +/- 26.9) and had a significantly higher number of RE/year (mean = 4.3 +/- 2.9; P less than 0.01 vs. no CAD, CAD alive). Autopsy (n = 6) and angiographic studies (n = 46) demonstrated diffuse, concentric, obliterative arterial disease in all vessels (type A) in 6 patients (RE/yr: mean = +/- 5.5 +/- 2.3), single stenoses in major coronary vessels (type B) in 7 patients and ordinary atherosclerosis (3-vessel disease) comparable to ischaemic heart disease (type C) in 3 patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Coronary Disease↗
PubMed1990

Functional cardiac imaging in coronary disease: increased sensitivity of first-pass radionuclide angiography utilizing sequential regional left ventricular early diastolic filling rate images.

In 127 patients, 113 with greater than or equal to 50% coronary artery stenosis (CAD), 14 with normal coronaries, cardiac catheterization and first-pass radionuclide angiography (RNA) utilizing left ventricular (LV) regional ejection fraction, first half systolic LV regional mean transit time and ejection rate images were performed. Additionally, the incremental value of a new technique, sequential regional LV filling rate images focusing on the first third of diastole, was established. Diastolic imaging improved RNA sensitivity from 88% (100/113) to 96% (109/113). Single vessel disease sensitivity increased from 77% (23/30) to 90% (27/30), whereas multivessel disease RNA positivity changed from 93% (77/83) to 99% (82/83). LAD system (LAD/D) sensitivity improved by 24% to 94% (79/84); RCA system (RCA/PDA) sensitivity increased 17% to 84% (59/70); circumflex system (CFX/OM) sensitivity was 83% (67/81), an improvement of 5%. Specificity was well maintained despite the increased sensitivity, as 86% (12/14) of patients with normal coronaries were normal by RNA. Furthermore, in the 113 CAD patients, 81% (84/104) of the vessels with insignificant or no stenosis were normal by RNA. We conclude sequential regional LV diastolic filling images substantially increase RNA sensitivity for CAD, while specificity is satisfactorily maintained.

Coronary Disease↗
PubMed1990

[Changes in R wave voltage during exercise: are they a sign of changes in ventricular volume or of myocardial ischemia?].

In an attempt to assess the significance of R wave amplitude changes during exercise in patients with coronary artery disease, we retrospectively analysed radionuclide as well as exercise test results of 147 patients with either suspected or already ascertained coronary artery disease, 126 men and 21 women, whose mean age was 56.0 +/- 9.3 years, 56 of which with previous myocardial infarction (16 on the anterior, 33 on the inferior and 7 on the lateral wall), who underwent a simultaneous evaluation of regional ventricular function by means of first pass angiography with multielement gamma-camera and of myocardial perfusion by means of single photon emission computerized tomography. All patients received 2 iv injections of 99mTc-methoxy-isobutyl-isonitrile at rest and at peak of a computerized bicycle stress test, whose end-points were ST segment depression greater than or equal to 1 mm or the attainment of a heart rate greater than 85% of maximal age-predicted one. R wave amplitude was measured by means of a magnifying lens on an averaged ECG complex, selecting for each patient the precordial lead showing the largest R wave amplitude. Absolute values of left ventricular volumes were computed by means of a standardized method from first pass angiography data. Patients were divided in subgroups according to the presence and to the number of coronary territories with evidence of stress-induced myocardial ischemia at radionuclide study.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1989

Right ventricular dysplasia: radioisotopic angiography.

To evaluate if regional wall motion (RWM) abnormalities detected at rest in patients with high presumption of right ventricular dysplasia (RVD) are confirmed by stress test and could be considered of diagnostic value in the clinical setting of the disease, 12 patients underwent first-pass radionuclide angiography (RA) at rest and during exercise. The mean global right ventricular ejection fraction (EF) was 29.83 +/- 7.91 at rest; during exercise, we found a non-significant increase (32.16 +/- 9.8, P greater than 0.05). Six segments with systo-diastolic dyskinesis, three segments with diastolic dyskinesis, and 10 segments with akinesis at rest confirmed the same degrees of dysfunction during exercise. Eight of the 15 hypokinetic segments at rest showed normal function during exercise; the remaining seven confirmed the same degree of dysfunction during exercise. We conclude that various degrees of RWM abnormalities are found in all patients with RVD; hypokinetic dysfunction has to be confirmed by exercise. RWM abnormalities are not specific for RVD, and clinical and electrophysiological data should be combined to obtain as much evidence as possible for diagnosis.

Adolescent↗
PubMed1988

[MacLeod's syndrome. Observations on 6 cases].

Mac Leod's syndrome is a rarely diagnosed disease; that is why an accurate differential diagnosis is needed by means of radiological imaging. This paper is aimed at discussing the differential diagnosis, with a special emphasis on the pathogenesis of the syndrome. The phenomenon of air trapping in absence of central bronchial lesions is a typical radiographic finding. Chest X-ray is performed in both inspiration and expiration. Posterior oblique tomography at 55 degrees of the affected side is also performed. Diffuse bronchiolitis obliterans in infancy or early childhood is a widely accepted pathogenetic pattern. Pulmonary hypoventilation causes vasoconstriction and underdevelopment of pulmonary vessels, that are reduced in caliber. Differential diagnosis includes all the diseases resulting in pulmonary hyperlucency, i.e. pulmonary and pleural alterations, and skeletal anomalies.

Adult↗
PubMed1987

[Comparison of MR examinations of the heart with first-pass radionuclide ventriculography].

72 patients with various heart diseases were studied by the use of magnetic resonance tomography and first-pass radionuclide angiocardiography. Both methods were compared in the RAO projection to determine the regional correspondence of morphological and functional alterations. The study proved that severe structural and functional disorders are usually combined (global correspondence for all patients 75%). Regionally, however, discrepancies between function and tissue-structure can be observed particularly in patients with anterior wall infarcts at the upper segments. Patchy signal patterns were found to correlate regionally with significant dysfunction particularly during the rapid filling phase.

Cardiomyopathy, Dilated↗
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↗