Central Body Temperature as a Guide to Optimal Heart Rate

Les stimulateurs cardiaques à fréquence fixe ne restaurent pas la fonction hémodynamique normale. Puisque un pourceniage élevé de patients porteurs ?un stimuJateur cardiaque a des anomaJies auriculaires, un outre moyen de “piloter” le pacemaker est présentér celui de la témperature du sang dans ľoreillette droite. Les sondes à enregistrement thermique mesurent la variation de température pendant ľexercice et peuvent servir de guide pour déterminer la fréquence cardiaque optimale. Studies in man suggest that fixed‐rote artificial pacemakers do not return hemodynamic function to normal, since the principal mechanism for the increase in cardiac output with exercise, increased heart rate, is not restored. Special pacemakers are available that can detect atrial activity and pace the ventricles in coordination, but nearly half of the patients receiving artificial pacemakers have abnormal atrial function fatrial fibrillation, sick sinus syndrome). This study examined the effects of exercise on the temperature of blood returning to the right atrium. Precision thermistors, placed in the right hearts of conscious dogs, recorded temperature increases of 1°C (range 0.4–1.5°C) during submaximal treadmill exercise. Temperature change correlated well with work load and changes in heart rate.