Respiratory Rate as a Determinant of Optimal Pacing Rate

Des essais ont été faits dans ľutilisation des paramètres bialogiques pour déterminer la fréquence optimale de stimulation cardiaque. Dans cette étude, le rapport entre fréquence respiratoire et fréquence cordiaque a étéétabli chez 67 patients au cours de ľexercice. Ensuite, un système de stimulation cardiaque qui repondrait àľactivation radiotélémétrique a été posé chez onze patients. Dans deux cos un système automatique a été implanté avec succès. A present, les résultats de cette stimulation pilotée par la fréquence respiratoire sont satisfaisants.
Efforts have been made to utilize biologic parameters for determining optimal cardiac pacing rates. In this study of 67 patients, a significant relationship between heart rate and respiratory rate was observed during dynamic exercise. A system using a radiofrequency activator to modify pacing rate is described. Eleven patients have received VVI pacemakers with a similar implanted radioreceiver coil. In two patients the fully automatic system has been successfully implanted. The experience with respiratory rate as a determinant of pacing rate is encouraging.     

Increasing Cardiac Rate by Tracking the Respiratory Rate

Un stimulateur asservi qui utilise la fréquence venlilatoire comme capteur a été implunté chez 22 patients, dont 19 pour la stimulation ventriculaire et 3 pour la stimulation auriculaire. Le niveau d'exercice atteint en utilisant ce système a été toiijours supérieur à celui de la stimulation ventriculaire à fréquence fixe. En plus, aucun capteur chimique ou mécanique n'était utilisé; le capteur même est simple, durable et utilise une faible énérgie. Done, ce système s'adapte facilement à chaque patient individuel.     

Angiographic Correlates of Different Mechanical Effects During the Dipyridamole Echocardiography Test Shortly After Acute Myocardial Infarction

The aim of this study was to analyze the different mechanical patterns during the dipyridamole echocardiography test (DET) performed in 167 patients 8–10 days after a first myocardial infarction. The results were correlated with coronary angiography. In a first series of 98 patients retrospectively analyzed (group I), four different types of dipyridamole-induced wall-motion abnormalities were observed: (1) worsening of wall motion in the same region showing asynergy at rest (type I); (2) new wall-motion abnormality in a territory adjacent to the resting asynergies and fed by the same vessel (type II); (3) new wall-motion abnormality in a territory adjacent to the resting asynergies, but supplied by a vessel different from the infarct related artery (type III); and (4) new wall-motion abnormality not directly adjacent to the infarct zone (type IV). Type IV asynergies were found in one of 44 patients with single vessel disease and in 14 of 54 patients with multivessel disease (sensitivity 70.4%, specificity 92.3%). Type III asynergies developed in two patients with single vessel disease and in 24 of those with multivessel disease. The frequency and distribution of the four asynergy types were subsequently analyzed in a second prospective series of 69 patients (group II). Type III and IV asynergies were found almost exclusively in patients with multivessel disease (17/34 patients with multivessel disease and 2/35 with single vessel disease) (sensitivity 50%, specificity 94.3%). Combining type III and IV asynergies, an overall sensitivity of 62% and a specificity of 94% for predicting multivessel disease were obtained. The ability of DET to predict specific vessel obstruction was also investigated. A positive correlation was found only for the laterobasal segment (specificity 82% in predicting critical stenosis of the left circumflex artery [LCX]), and for the apical and distal septal segments (specificity 95% and 93% for lesions of the left anterior descending artery [LAD], respectively). A substantial overlap was noted when an attempt was made to distinguish LCX from right coronary artery (RCA) lesions. Nevertheless, new simultaneous wall-motion abnormalities of the posterobasal septal and laterobasal segments were observed in all but one patient with combined lesions of LCX and RCA (specificity 99%). In conclusion, the mechanical patterns of dipyridamole-induced new wall-motion abnormalities correlate with coronary angiography: new remote asynergies are highly specific in predicting multivessel disease, but are not frequent. New asynergies adjacent to the infarct zone can also predict multivessel disease, provided they are located in a different vascular region. The ability of DET to predict specific vessel obstructions was excellent for LAD lesions, but it was less helpful in differentiating LCX from RCA lesions. Nevertheless, new simultaneous wall-motion abnormalities of the posterobasal septal and laterobasal wall predict critical lesions of the LCX and RCA.