[Short-axis thallium 201 tomography. Changes in the isotope fixation on the circumference of the left ventricle]. / Tomographie au thallium 201 en coupes petit axe. Etude de la variation de fixation de l'isotope sur la circonférence du ventricule gauche.

Several authors have studied variations in myocardial thickness on short-axis sections cut through healthy postmortem hearts. The circumferential profiles showed a series of minima and maxima, with a minimum at the septum, a maximum at the anterior interventricular junction and another at the anterolateral papillary muscle, a minimum at the inferior wall followed by a maximum at the posterior papillary muscle, then at the posterior interventricular junction, after which came a septal minimum again. When examined by short-axis thallium 201 tomography, the left ventricle does not look like a ring of even density. The purpose of this study was to try and explain the changes in density observed by variations in thickness and to devise a quantification method that would take anatomical features into account. 23 patients with normal coronary angiography underwent thallium 201 scanning after exercise. Circumferential profiles were drawn from short-axis sections with the angle on the abscissa and the number of sections on the ordinate. 29 other patients with a more than 75 p. 100 stenosis of coronary vessels (anterior interventricular artery 15, right coronary artery 10, circumflex artery 8, diagonal artery 4) had the same examination. The circumferential profiles of normal subjects closely resembled those of anatomical sections, with a minimum at the upper and anterior septal wall (the limit between the two areas being undefinable), a maximum at the anterolateral papillary muscle and adjacent myocardium, a minimum at the inferior wall and a maximum at the posterior papillary muscle and adjacent septum. These curves enabled us to determine the relative perfusion values of one area compared with another, which will serve as reference.(ABSTRACT TRUNCATED AT 250 WORDS)

[Quantitative thallium myocardial tomoscintigraphy. Value of intravenous infusion of dipyridamole after negative submaximal exercise test]. / Tomoscintigraphie quantifiée au thallium. Intérêt d'une injection intraveineuse de dipyridamole après une épreuve d'effort sous maximale négative.

Patients with suspected coronary artery disease are sometimes unable to exercise adequately (85% of age calculated maximal heart rate) to validate their ergometric stress test. Some groups suggest performing dipyridamole scintigraphy from the outset but then the information provided by exercise stress testing is lost. The aim of this study was to compare scintigraphies performed after exercise alone and after exercise combined with dipyridamole using a method of quantification. Thirteen patients with ischaemic heart disease without necrosis (coronary lesions greater than 75% luminal narrowing in: 7 right coronary, 10 left anterior descending, 3 left circumflex arteries and 1 left main coronary artery with 50% luminal narrowing) underwent exercise stress testing followed by Thallium imaging. One week later, the same exercise stress test was performed followed by an intravenous injection of dipyridamole and Thallium scintigraphy. The circumference of the radioactivity was traced and the surface of each segment calculated in three different short axis views, subdivided into 4 segments (anterior, lateral, inferior and septal walls). Any segment vascularised by a stenosed coronary artery was considered to be underperfused (105 segments). The ratios of the surfaces of underperfused/normal segments were compared using the two study protocols. Segments of the same wall in the 3 short axis views were grouped in the same myocardial zone. Thirty five myocardial zones were thus obtained: 25 zones were more underperfused after combining exercise and dipyridamole than after simple exercise stress (p = 0.014). The average increase in underperfusion after the combined exercise-dipyridamole was 12.4% compared with 5.5% after exercise alone (p = 0.03). Secondary effects were minimal.(ABSTRACT TRUNCATED AT 250 WORDS)

[Role of myocardium scintigraphy with thallium dipyridamole in the evaluation of arterial disease of the legs]. / La place de la scintigraphie myocardique au thallium dipyridamole dans le bilan de l'artériopathie des membres inférieurs.

Thirty-eight consecutive patients with severe arterial disease of the lower extremities benefited from an exploration of the coronary reserve by myocardial scintigraphy with thallium dipyridamole. With this examination, it has been possible to screen 20 p. cent of asymptomatic patients and at least modify the perioperative treatment or even the very indication for surgery.

[Study of muscle hemodynamics during exercise: Physiological and pathological variations in Xe 133 elimination: A new method of interpretation (author's transl)]. / Etude de l'hémodynamique musculaire au cours de l'exercice. Variations physiologiques et pathologiques de l'élimination du 133 Xe. Nouveau modèle d'interprétation.

Muscle blood flow measurements are of physiological (and pathological) significance only during effort. For this reason, the authors used Xe 133, which has been known since 1964, to measure regional muscle blood flow after its injection into the muscle, to quantify results during effort (pedalling). Effort is controlled by two measurable parameters: the weight lifted by the pedal and the frequency of movements. Curves showing the reduction in intramuscular Xe 133 levels cannot be mathematically formulated. It is easy, however, to measure their areas and thus define a mean elimination time (Tm) between times T1 and T2, beginning and end of effort, corresponding to activities A1 and A2 such that: formula: (see text). Normal Tm value, measured in 58 normal subjects with variable frequencies and weights lifted is: Tm = 1.70 +/- 0.38 min. The values in 70 patients with arteritis were significantly longer and can be greater than 3.5 min. This objective test could be of value in quintifying the effects of so-called vasodilators, both in patients with arteritis and venous insufficiency.