[Comparison of the pyrophosphate and gluconate cardiac scan in the diagnosis of experimental pericarditis in dogs].
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Biomedical subjects
Publications and source records attributed to P Kafka.
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In 10 dogs experimental cardiomyopathy was produced using high intravenous doses of adrenaline and theophylline. The possibility of scintigraphic detection of this non-ischaemic damage was tested by means of 99mTc-gluconate. In 5 dogs the scintigraphic examination was carried out 4 hrs following the production of the damage. In all 5 cases a marked positivity of the heart scan was observed. The finding was confirmed by the radioactivity of tissue samples from all sections of the heart. In 3 out of 5 dogs the histological examination of the myocardium (PAS and HBFP staining) was positive. In the remaining 5 dogs the scan was performed 24 hrs following the development of the damage. A positive scintigraphic finding was observed in 4 cases, the degree of accumulation being lower than at 4 hrs. The radioactivities of tissue samples were also significantly lower as compared with the 4-hr values. In contrast, the histological findings were markedly positive in all 5 dogs. It follows that 99mTc-gluconate is capable of detecting in addition to infarctions non-ischaemic damages to the myocardium, too. The normalization of the finding is very quick. This experimental finding appears to be of importance in clinical practice.
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Scintigraphic examination of the myocardium, using 99mTc-labelled pyrophosphate, was carried out in 17 patients suffering from systemic sclerosis. This connective tissue disorder very often affects the myocardium secondarily. The results of the cardiac scan were compared with the information obtained from the electrocardiogram of systolic time intervals. In addition, spirometry was undertaken to detect a potential relation between cardiac and pulmonary involvement. The scan was found to be positive in seven patients and electrocardiographic findings were pathological in five patients only. The systolic time intervals were abnormal in three patients only. A ventilation disturbance was recorded in 10 patients. No clear relation was found between the results of the individual examinations. It is concluded that pyrophosphate heart scintigraphy may detect myocardial impairment in some cases of systemic sclerosis before it is manifested by heart failure. Examination of systolic time intervals is of little importance.
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In the present paper the possibilities of scintigraphic diagnosis of experimental pericarditis are discussed. Pericarditis was induced by either talc or formaldehyde intrapericardially. In all animals the administration of talc as well as formaldehyde produced inflammatory changes which were more serious after formaldehyde. The scan of the talc pericarditis was carried out on the 7th day after operation and of the formaldehyde pericarditis on the 3rd, 7th or 14th days. No positive scintigraphic finding was made in any of the experimental animals, apart from a massive incorporation in the operation scars. The counting of radioactive impulses after the exstirpation of the tissue samples confirmed the scintigraphic findings. Statistical evaluation did not reveal any essential difference between the accumulation of the radiopharmaceutical into the pericarditis as well as into the pericardial bag in comparison with the control animals. Although our model does not exactly reflect the situation of patients suffering from pericarditis it may be assumed that pyrophosphate scintigraphy is not suitable for the diagnosis of acute pericarditis in clinical practice.
Scintigraphic examination of the myocardium using 99mTc-labelled pyrophosphate was carried out in 10 dogs with experimentally produced cardiomyopathy. This was brought about by intravenous administration of high doses of adrenalin and theophylline. The scan was positive in 8 out of 10 dogs. "Hot" foci were very extensive. The degree of accumulation was however low (2+). Histological examination of the myocardium using the light microscope showed only scarcely distinguishable damage to the tissue without the presence of necrosis. ECG examinations were normal in all cases. By means of 99mTc-labelled pyrophosphate even very small myocardial disorders can thus be detected. This fact may be of clinical importance for an early diagnosis of heart lesions.
In 9 dogs a transient myocardial ischemia was provoked using complete occlusion of the ramus interventricularis anterior of the left coronary artery. The occlusion was removed after 5, 10 or 15 min. Four hrs after removal of the occlusion a scan of the myocardium was carried out using 99mTc-labelled pyrophosphate. In 7 out of 9 dogs under study the scan was markedly positive, in 2 dogs negative. ECG demonstrated ischemic changes practically in all dogs; the changes became normal after removal of the occlusion, namely in 5 to 35 min. The histological examination of the tissue demonstrated in all 9 dogs only a slight impairment of the myocardium.
A survey is presented of research results of pyrophosphate myocardial scanning in 130 dogs and 150 patients with various myocardial lesions. The results of experiments in animals were immediately applied in clinical practice. The results showed that acute transmural myocardial lesions yielded practically in all instances positive scintigraphic findings. The findings in nontransmural infarctions were less convincing--they were positive in 60% of cases. Positive scintigraphic findings were also obtained in 80% of dogs with experimentally induced temporary ischaemia, and in 80% of dogs with experimentally induced dystrophy of the myocardium. In patients with angina pectoris positive findings were obtained in 1/3 of the cases, and in patients with cardiomyopathies, in 1/3 to 1/4 of the cases (in dependence on the etiology of the cardiomyopathy). It appears that 99mTc-PYP is a highly sensitive, but nonspecific, detector of myocardial lesions.
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