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Biomedical subjects

R Montz

Publications and source records attributed to R Montz.

At least 55 records · Page 3Linked to original sources
PubMed1985

Hypertrophic cardiomyopathy: non-invasive assessment of diastolic and systolic functional parameters in relation to heart rate.

Hypertrophic cardiomyopathy (HC) is characterized by reduced left ventricular compliance and subsequent filling abnormalities. To study the pathophysiologic changes in parameters of left ventricular systolic and diastolic performance as a function of increasing heart rate 14 patients with HC (32 +/- 12 yrs; 11 M, 4 F) and 4 normal individuals were subjected to equilibrium radionuclide ventriculography (99mTc-labelled red blood cells) at rest and during incremental right atrial pacing; heart rate was increased in steps of 20 beats per min from basal state to the individual symptom-limited endpoint. Mean symptom-limited heart rate was 141 +/- 28 in HC and 160 in normals (p less than .01.). At each pacing level filling and ejection parameters as well as the left ventricular endsystolic (LVESV) and enddiastolic volume (LVEDV) were determined relative to resting volumes at a heart rate of 78 +/- 8. At the individual maximal pacing rate HC revealed a decline in LVEDV to 61 +/- 4% (p less than .001) and an increase in LVESV to 117 +/- 14% (p less than .001) resulting in decreasing ejection fractions at heart rates above 120. Peak LV filling rates initially increased but subsequently decreased steeply at heart rates above 100; peak LV ejection rates in HC showed a similar pattern with increasing frequency. Time intervals to peak ejection and peak filling rate did not differ from normal. Thus, patients with HC demonstrated combined left ventricular diastolic and systolic abnormalities with increasing heart rate leading into a low-input low-output circulatory state. This probably explains not only the symptoms associated with HC, but also supports the concept of "hemodynamic syncope" in HC.

Adolescent↗
PubMed1985

[The 4 hr-washout-functional picture: a quantitative visualization of 201Tl myocardial stress kinetics and the significance of paradoxical redistribution].

Between March and August 1983, 62 patients with suspected coronary artery disease were investigated by both 201Tl myocardial scintigraphy and coronary angiography. Functional images of the 4 h-201Tl-washout were compared with conventional scintigrams of the stress and rest phases and with results of coronary angiography. Myocardial scintigraphy with 4 views was performed immediately after exercise and 3-4 h later. After interpolative background subtraction, 4 h-washout functional images were computed from each of the initial scintigrams and the corresponding delayed scintigrams. Using a special-coded colour table, the 4 h-washout could be read quantitatively from the functional image. The additional analysis of washout images increased the accuracy of myocardial 201Tl scintigraphy for the detection and localization of coronary stenoses from 42% to 69%. Sensitivity increased from 42% to 73%, definitivity from 50% to 79%. Ischemic regions appeared more obvious in the washout images, even to less experienced observers. In comparison with circumferential washout profiles the interpretation of washout images was easier because of more obvious anatomical localization. The phenomenon of "reverse redistribution" was found to be associated with a decreased 201Tl-washout in apparently "normal" regions, whereas in those regions with "reverse redistribution" the washout was normal or at least relatively high. In addition diffuse myocardial ischemia occurring in 3-vessel disease could be recognized in the 4 h-washout functional images.

Coronary Disease↗
PubMed1985

[Function scintigraphy: a uniform method for quantifying organ metabolism and function].

Functional scintigraphy is a quantitative method with which metabolic parameters of an organ can be determined by measuring the time activity course of a radioactive tracer in tissue. Their quantitative value is, however, limited by inherent sources of error, e.g. the absorption of radiation in the organ or overlapping of fore- and background activities. Hitherto, existing procedures for calculation of metabolic parameters are based more on given technical possibilities than on common theoretical foundations. They are notable for their variety in methodical approach, frequently being of empirical character. Quantitative results from different institutes and hospitals can therefore rarely be compared. The present work describes a methodical approach to obtain comparable methods in nuclear medicine, by including the pharmacokinetics of a tracer in blood. This leads to the compartment analysis (deterministic) or to a stochastic (non-deterministic) description of the kinetics in an organ. The stochastic description requires the calculation of the linear response function from a convolution integral. By means of functional analytical methods a mathematical procedure has been developed which for the first time permits the calculation of the linear response function in each pixel and at any time of the study. Easily readable functional images show how relevant parameters can be calculated from the linear response function. Due to its independence on any model, the linear response function enables furthermore a regional investigation of existing or new compartment models of tracer kinetics in the organ concerned.

Bone and Bones↗
PubMed1984

Assessment of myocardial necrosis immediately after intracoronary thrombolysis by intracoronary injection of technetium-99m pyrophosphate.

To assess myocardial necrosis immediately after intracoronary thrombolysis, thallium-201 (TL-201) and technetium-99m pyrophosphate (Tc-99m PYP) were injected simultaneously into the coronary artery in 25 patients with acute transmural myocardial infarction. In 17 of the 25 patients, the occluded coronary artery was reopened. Minutes after the intracoronary injection of Tc-99m PYP into the reopened coronary artery a localized accumulation was seen within the area of the Tl-201 defect in all patients. Control intravenous scintigraphy, which was performed in 8 of these 17 patients 1-6 days later, and in 2 patients 18 and 42 days after infarction, revealed a Tc-99m PYP spot similar to that of the acute intracoronary Tc-99m PYP scintigram in all 10 patients. In the 8 of the 25 patients, in whom intracoronary thrombolysis failed, no localized Tc-99m PYP accumulation was seen after injection into the infarct vessel. In 5 of these patients, a control intravenous scintigram, performed 1-8 days later, resulted in a Tc-99m PYP spot in the area of the Tl-201 defect. We conclude that, in the presence of therapeutic or spontaneous reperfusion, Tc-99m PYP scintigraphy may provide a useful method of assessing myocardial necrosis during the early stage of an acute myocardial infarction.

Adult↗
PubMed1984

Intracoronary thallium 201 scintigraphy as an immediate predictor of salvaged myocardium following intracoronary lysis.

Since February of 1980, 157 patients who had had symptoms of acute myocardial infarction for less than 3 hours underwent intracoronary lysis. Forty-six patients required early aorta-coronary revascularization. However, operation was believed to be indicated only when intracoronary lysis was successful and myocardium was salvaged. Since left ventricular angiography proved unreliable in assessing the viability of the myocardium in the acute stage, starting in March of 1981 we obtained intracoronary thallium 201 scintiscans in 23 patients before and after intracoronary lysis. Patients in whom there was a significant reduction (greater than 50%) in the initial 201Th defect (n = 12) were considered ideal candidates for operation (Group 3). Patients with poor or unimproved 201Th uptake after successful intracoronary lysis (n = 6) were treated medically (Group 2), as were patients in whom intracoronary lysis was unsuccessful (n = 5, Group 1). In order to validate this new approach, we compared the change in the regional wall motion of the "infarcted area," as shown in the early and follow-up left ventricular angiograms in all three groups. In the acute stage, the mean regional ejection fraction was 19.9% in Group 1, 19.1% in Group 2, and 20.1% in Group 3. Only in Group 3 was there a significant increase in regional ejection fraction to a mean of 51%. The mean ejection fraction obtained at follow-up in Groups 1 and 2 was 16.5% and 17.3%, respectively. From our findings, we conclude that 201Th scintigraphy is a valuable predictor of the salvageability of myocardium immediately following intracoronary lysis. To date, it has been the most valuable tool in assessing those patients suitable for early coronary revascularization.

Coronary Vessels↗
PubMed1983

[Preoperative localization diagnosis of parathyroid adenomas in 72 cases of primary hyperparathyroidism by selective catheterization of neck veins and parathyroid hormone determination].

In 72 cases of primary hyperparathyroidism, selective venous catheterization was performed preoperatively to localize parathyroid adenomas. Diagnosis of primary hyperparathyroidism was proved by operation in all but 5 cases, in which no adenomas could be found intraoperatively. By venous catheterization of the neck and upper region of the thorax, an average of 10 blood samples per patient were taken. Parathyroid hormone was estimated by radioimmunoassay with high sensitivity against the intact PTH-molecule and carboxy-terminal fragments. Only in 24 out of 72 cases was localization of parathyroid adenomas prognosticated correctly with respect to side and height, while in a total of 38 cases localization on the right or left side only could be determined preoperatively. These unsatisfactory results can be improved only by a much more extensive catheterization technic which would be justified only in patients already operated on before without success. The final evaluation of non-invasive methods, e.g. ultrasonics and computerized tomography, is still under discussion.

Adenoma↗
PubMed1983

[Biokinetics of osteotropic radiopharmaceuticals in metabolic osteopathy--comparison of 47Ca and 99mTc-methylene-diphosphonate (MDP)].

Plasma clearance and osseous accumulation rates of 99mTc methylene diphosphonate (MDP) in the lumbar spine were measured in 11 patients with osteoporosis (OP), 7 patients with hyperparathyroidism (HPT), 4 patients with osteomalacia (OM) and in 3 patients (N) who were studied to exclude metabolic bone disease. The findings in 19 patients were compared with the results of 47Ca kinetics. The plasma elimination of 99mTc-MDP during the first hour after application was normal in almost all the patients. The 99mTc-MDP accumulation rates in the lumbar spine were raised in patients with HPT and OM (p less than or equal to 0.01) and normal in patients with OP and N (p greater than 0.05). 47Ca kinetics were disturbed in most of the patients with metabolic bone disease, with minimal deviations in OP. The comparison of 99mTc-MDP accumulation rates with the results of 47Ca kinetics revealed significant correlations with exchangeable bone and soft tissue calcium. The correlations with total calcium turnover and calcium accretion were poor. Only half of the patients had equal results of 99mTc-MDP accumulation rates and bone calcium accretion rates. It is concluded that the 99mTc-MDP uptake by bone is an index of bone metabolism presumably of the organic matrix, whereas 47Ca kinetics represent the mineral metabolism of bone.

Adult↗
PubMed1983

Quantification of tracer kinetics in intra- and extrahepatic bile ducts and of gallbladder filling rates in hepatobiliary dynamic scintigraphy using 99mTc-IDA derivates.

A method is presented of calculating the flow of 99mTc-labelled IDA derivates in intra- and extrahepatic bile ducts. By computer means the superimposed liver parenchymal activity is subtracted from the original sequence data in each pixel and at each time. In addition to known evaluation methods, the described procedure seems to be helpful for clinical application in order to better display anatomical details of intrahepatic structures like bile ducts and to calculate quantitative parameters like appearance times in intra- and extrahepatic regions. Examples are given and the possibility of calculating a gallbladder filling rate for separating normal gallbladders from stone-filled ones is statistically proven.

Adult↗
PubMed1982

[Cardiac involvement in sarcoidosis (author's transl)].

Standard electrocardiogram (ECG), His-bundle electrogram and biphasic thallium myocardial scanning was undertaken in 13 patients with histologically confirmed sarcoidosis (lung stages I--III). Changes in the standard ECG were present in five (sinus bradycardia, A-V nodal and intraventricular conduction disturbances, non-specific S-T--T changes). The His-bundle electrogram was abnormal in four of eleven patients in whom it was recorded (sick-sinus syndrome, supraventricular extrasystoles, damage to A-V node and supraventricular extrasystoles, damage to A-V node and intraventricular conduction disturbances). In seven of twelve patients who had thallium scans there was a definite irreversible defect, questionable abnormality in three others. Seven of ten patients who had all three tests had definite abnormalities in at least one of them. The electrophysiological findings and the abnormal scans point to cardiac involvement in sarcoidosis.

Adult↗
PubMed1982

[Sterile vesiko-ureteral reflux. Radiological kidney surface measurements as follow-up criteria].

33 patients with 46 sterile vesicoureteral refluxes were followed by repeated clinical-urological and radiological studies over a period from 1 to more than 6 years. The results of the evaluation, obtained by only looking at the urograms, were compared with the following measurements: the length of each kidney, the length ratio right to left, and the parenchymal area. At the end of the follow-up period, 2 out of 32 initially normal kidneys (about 6%) had pathologically low values, whereas 3 out of 14 already initially damaged kidneys (21,5%) showed a further decrease of these values. Preceding urinary tract infections with consecutive pyelonephritis, leading to a progressive shrinkage of the organ over many years, are thought and discussed to be more responsible for these results than the sterile reflux itself.

Adolescent↗
PubMed1981

[Calcium and bone metabolism after jejunal bypass operation for alimentary obesity: model for a intestinally-conditioned disorder (author's transl)].

Jejuno-ileostomy was performed in eight women because of severe alimentary obesity. Their calcium phosphate and bone metabolism was studied an average of 31 months post-operatively. This revealed secondary intestinal hyperparathyroidism due to an artificial malabsorption syndrome. While most of the significant metabolic factors were within normal limits, examination of calcium balance and kinetics indicated a marked disorder of calcium and bone metabolism. Calcium balance averaged-138 mg daily, corresponding to a yearly loss of skeletal mass of 4-5%.

Adolescent↗
PubMed1981

[Diaphyseal dysplasia (Camurati-Engelmann syndrome) with progressive loss of vision: 30-year observations and the effect of prednisolone treatment (author's transl)].

Radiological changes in the skeleton had been present for 30 years in a now 42-year-old man with diaphyseal dysplasia (Camurati-Engelmann syndrome). Because of threatened blindness by bony narrowing of the optic canal prednisolone was administered over several years. Biochemical, calcium-kinetic and ophthalmological studies demonstrated a favourable effect of this treatment.

Adult↗