A clinical study investigates the use of Home Monitoring (HM) in pacemaker therapy. For 3 months patients are supervised by daily automatic HM messages. Endpoints are the technical feasibility and the clinical benefit of HM. Ninety three patients have currently been included and followed for 72 +/- 30 days. Three patients were excluded due to insufficient mobile net coverage at their living sites. For the other patients, 5311 of 5911 messages were successfully registered. Interrupts in the sequence of messages occurred 331 times. Two hundred ten of these (63%) lasted just 1 day, 14 interrupts (4%) lasted 5 or more days. Two patients did not show any interrupts, 34 patients (38%) had interrupts of 3 and more days. The clinical benefit of Home Monitoring was found in the remote detection of arrhythmia and lead dislocation.
Innovations in pacing technology, which include the addition of rate-responsive features to programmable pacemakers, can improve the quality of life of patients suffering from sick sinus syndrome. Among the strategies providing rate-adaptive cardiac pacing, the most attractive is the physiological restoration of closed-loop chronotropic control. This paper describes how autonomic nervous system (ANS) control information is extracted from dynamic measures of myocardial contractile performance obtained from unipolar conductance measurements using the stimulation electrode in the right ventricular cavity. The pacemaker uses the ANS information to modulate pacing rate and restore normal physiological control of heart rate. A new algorithm, regional effective slope quantity (RQ), for isolating the ANS signal was developed. The resulting signal, ventricular inotropic parameter (VIP), is a normalized parameter proportional to the strength of the ANS inotropic signals to the myocardium. The efficacy of the ANS control concept was evaluated in multi-centre studies. Patients with AV block and VIP-controlled pulse generators performed defined exercise protocols. The ANS-controlled pacing rate and the spontaneous sinus rate were closely correlated. Blood pressure and subjective patient reports further indicated that good control of the cardiovascular circulation was achieved.
A multicenter clinical study is presented, which focuses on the reestablishment of closed loop cardiac control in patients with chronotropic insufficiency. Using the information about sympathetic tone contained in the myocardial contractility, it is possible to reconnect the heart rate to the physiological control mechanisms. Intracardiac impedance is measured with the ventricular electrode and the ventricular inotropic parameter (VIP) is derived from that. The VIP serves directly as input to the control of heart rate by the pacemaker. Over 200 patients have received autonomic nervous system (ANS) controlled pacemakers. The patient-pacemaker system was investigated in different ways. This included standard exercise tests, long-term studies of every day activities over 24 hours, psychological, and pharmacological challenges. To prove the validity of the approach we specifically looked at (1) the appropriateness of changes in paced heart rate with sympathetic tone during exercise, (2) the correlation between heart rate and sinus rate, if detectable, and (3) the correlation between the echocardiographically determined preejection period (PEP) and the VIP controlled heart rate.
Our results underline the importance of the individual history in predicting perioperative risk and corroborate the beneficial effects of long-standing beta-blocker therapy. Additionally the significance of stable intraoperative hemodynamic parameter is demonstrated.
EINLEITUNGTechnologische Perfektion, Leistungsfähigkeit und Zuverlässig-keit technischer Herzschrittmacher sind in den letzten Jahren enorm gesteigert worden. Doch trotz aller Fortschritte war das Problem der physiologischen Frequenzanpassung unter normalen Alltagsbedingungen (körperliche, orthostatische, psychische oder thermische Belastung) bisher nicht befriedigend gelöst Alle verwirklichten Lösungsansätze, z.B. durch Störgrößenauf-schaltung wie bei der Erfassung von Beschleunigungen oder durch Berücksichtigung systemischer Größen wie der Temperatur oder der Sauerstoffsättigung im mischvenösen Blut, stellten offene und damit gesteuerte Systeme dar [1]. Im Gegensatz hierzu erfolgt die physiologische Frequenzanpassung in einem geschlossenen und damit geregelten System [2], Die entscheidende Bedeutung im physiologischen System kommt dem Autonomen Nervensystem (ANS) zu [3]. Mit dem hier beschriebenen Lösungsansatz wird die Frequenzanpassung mit der aus dem ANS abgeleiteten Information und somit unter Ausnutzung der vorhandenen physiologischen Funktionseinheiten (Barorezeptoren, medulläre Kreislaufzentren, afferente und efferente Bahnen des ANS) im geschlossenen System durchgeführt.
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