[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)

[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)

[Sustained ventricular tachycardia 7 years after complete correction of tetralogy of Fallot]. / Tachycardie ventriculaire soutenue 7 ans après correction complète d'une tétralogie de Fallot.

The authors report a case of sustained ventricular tachycardia which occurred seven years after complete surgical correction of Fallot's tetralogy in a 13 year old girl. This arrhythmia was well tolerated haemodynamically, showed right-sided delay and was associated with mitral valve prolapse. After reviewing the literature, several physiopathological mechanisms are discussed: --the role of residual intraventricular conduction defects in sustaining the tachycardia; --the role of the ventriculotomy scar or of other associated lesions (mitral valve prolapse in this case) in the genesis of ventricular extrasystoles; --the postoperative haemodynamic status in the tolerance of the arrhythmias. This is a rare complication with an incidence of less than 2% of survivors followed-up over long periods. There is a risk of sudden death in 38% of these patients with ventricular arrhythmias which justifies Holter monitoring and ECG stress testing for their detection.

[Lengthening of the direct sinoatrial conduction time: a criterion of sinus node dysfunction]. / L'allongement du temps de conduction sino-auriculaire direct: un critère de dysfonction sinusale.

In order to determine the significance of prolongation of the direct sinoatrial conduction time (DSACT), an attempt was made to record the sinus node potential in 110 patients which was successful in 84 cases. The DSACT was normal in 45 cases (Group A) and prolonged (over 130 ms) in 39 cases (Group B). The symptomatology, standard ECG and the results of investigation of sinus node function by atrial stimulation of the two groups were compared. The DSACT was prolonged in all 13 patients with paroxysmal sinoatrial block or the sick sinus syndrome, in 71% of 15 patients with permanent sinus bradycardia, in 88% of 22 patients with a corrected sinus node recovery time of over 525 ms, in 82% of 38 patients with a sinoatrial conduction time estimated by the extrastimulus method of over 130 ms or an abnormal zone II, in 80% of 39 patients with sinoatrial conduction times estimated by Narula's method of over 130 ms; therefore, 87% of the 35 patients with probable sinus node dysfunction had long DSACT. On the other hand only 2 out of 35 patients (6%) with apparently normal sinus node function had prolonged DSACT. These results indicate that prolongation of the DSACT is a sensitive and specific criterion of sinus node dysfunction. In cases of sinus node dysfunction dizziness and/or syncope without any known cause were common complaints in patients in Group B but absent in patients in Group A. A prolonged DSACT could be of prognostic significance in sinus node dysfunction.

[Evaluation of the sinoauricular conduction time: comparison of the recording of the sinus potential and Narula's method]. / Evaluation du temps de conduction sinoauriculaire: comparaison de l'enregistrement du potentiel sinusal et de la méthode de Narula.

The sino-atrial conduction time, measured by Narula's method (SACTN) is compared to the direct sino-atrial conduction time measured by recording the sinus potential (SACTD) in 55 patients, 20 with normal sinus function and 35 with sinus dysfunction. In the absence of sinus dysfunction, SACTN and SACTD are not significantly different and a significant but mediocre correlation (r = 0.57) is observed between the two parameters. Major discordances between the two methods are seen in 4 patients. In cases with sinus dysfunction, there was no correlation between SACTD and SACTN; SACTN is close to SACTD in 12 patients, but much shorter in 11 patients and much longer in 10 patients. These discordances raise the problem of the penetration of the sinus node by the extrastimulus in Narula's method. This method does not seem capable of giving a reliable evaluation of the duration of sino-atrial conduction.