Continuous Holter telemetry of atrial electrograms and marker annotations using a common Holter recording system: impact on Holter electrocardiogram interpretation in patients with dual chamber pacemakers

The impact of continuous telemetry of atrial electrogram and marker annotations on Holter ECG interpretation was assessed in 98 patients with bipolar dual chamber pacemakers (VDD pacemakers n = 29, DDD(R) systems n = 69). Atrial electrogram and marker annotations were continuously sampled by a telemetry coil that was externally positioned on the pacemaker pocket, amplified, and transduced to a three-channel Holter ECG recorder in addition to an ECG recording. Holter tapes were analyzed by two experienced investigators for quality of P wave recognition and episodes suspicious of pacemaker dysfunction. Initially, only the ECG channel was analyzed. Thereafter, results were compared to those achieved on the basis of the complete recording including atrial electrogram and marker annotations. Recognition of atrial rhythm was markedly improved by Holter telemetry. During 99.3% of recording time telemetry showed a satisfying quality, whereas ECG alone allowed a reliable P wave recognition only during 84.4% of recording time (P < 0.001). One hundred twenty-nine episodes suspicious of pacemaker malfunction occurred in 17 of 98 patients. By analysis of ECG, only 78.3% of episodes were concordantly classified by the investigators. However, 98.4% of all episodes were properly identified when atrial electrogram and marker annotations were added to the analysis (P < 0.001). In particular, discrimination between atrial undersensing, sinus bradycardia, and atrial sensed events within the refractory periods was facilitated. Holter telemetry of atrial electrogram and marker annotations facilitates the analysis of Holter ECGs in pacemaker recipients and improves the detection of pacemaker dysfunctions.     

Diagnosis of Atrial Arrhythmias Using the Holter Function of a New DDD Pacemaker

The extension of random access memory now makes it possible to store electrocardiographic (ECG) information, referred to here as Holter function (HE), in the memories of new pacemakers, which can be used as diagnostic tools during long-term follow-up. This report describes our experience in 26 consecutive patients for whom the device was used to detect episodes of atrial arrhythmias (AA). An illustrative case is also presented to describe in detail the device's analytical method. Results: Fourteen AA profiles were successfully recorded in 10 patients by the pacemaker HF and correlated with confirmatory simultaneous surface ECG tracings. Three additional profiles were recorded in three other patients without simultaneous ECG recordings. A diagnosis of AA is established when the following findings are combined: (1) in all cases a large number of short interatrial inteivals (A INT); (2) in presence of AV block, interventricular intervals (VINT) stored between the lower programmed pacing rate and the upper rate limit or the fallback rate; (3) in absence of AV block, V INT stored between the basic rate and the AV node refractory period; (4) in case of fallback, (VVI function) no stored AV INT; and (5) in absence of fallback, great variability of AV INT (Wenckebach function). Conclusions: (1) Diagnoses of AA can be made with the pacemaker HE; (2) The homogeneity of the HF profiles makes them useful for long-term follow-up and will probably contribute and clarify the natural history of AA in DDD patients; (3) HF may also serve to monitor the safety and efficacy of antiarrhythmic drug therapy during long-term follow-up.     

Spontaneous Heart Activity in Pacemaker Treated Patients with High-grade Atrioventricular Block A Holter Monitor Study

A Holter monitor study. A Holter monitor study was performed to assess the occurrence of spontaneous heart activity in 70 pacemaker treated patients (mean age 72.1 years) with high-grade atrioventricular (AV) block, who had been treated with permanent pacemakers for a mean of 60 months (range 5-161). Nineteen patients had asynchronous (VOO), and 51 QRS-inhibited (VVI) pacemakers. The patients were monitored for a mean of 23 hours (range 15.5-26). Twenty-five patients were re-studied for day-by-day variations in spontaneous heart activity. At clinical observation, thirty-eight patients had pacemaker rhythm only. During monitoring, all patients studied had some kind of spontaneous cardiac activity, mostly ventricular ectopic beats. Three patients had short episodes of sinus rhythm of more than 70 beats/min. Patients in functional class III-IV (NYHA) or with an enlarged heart had the most spontaneous heart activity; those with asynchronous pacemakers had the least spontaneous cardiac activity. No tachyarrhythmias precipitated by interference between intrinsic heart beats and asynchronous pacemakers were seen. Twenty patients studied twice had a relatively stable occurrence of spontaneous heart activity, while five (20%) varied considerably. On the basis of these long-term observations it is difficult to predict when interference rhythm will occur, and asynchronous pacemakers therefore cannot be recommended for the first implantation. (PACE, Vol. 4, November-December, 1981)     

Dynamic Relationship Between the Q-aT Interval and Heart Rate in Patients with Long QT Syndrome During 24-Hour Holter ECG Monitoring

The purpose of this study was to investigate the dynamic relationship between heart rate and the Q-aT interval (the interval from the Q wave to the T wave apex) in patients with long QT syndrome. The QT to heart rate relation is useful for evaluating abnormalities of the ventricular repolarization, but its clinical application to the long QT syndrome requires accurate computer aided measurement of the QT interval and the sampling of a large number of beats. Therefore, the Q-aT interval was used on the basis of some reports that the heart rate dependency of the QT interval was concentrated in the Q-aT interval. Recent advances in the computer technology have allowed analysis of the relationship between the Q-aT and RR intervals on Holter ECG recordings. However, in addition to a prolonged QT interval, most patients with long QT syndrome have bizarre and variable T waves and the influence of this T wave morphology on the Q-aT to heart rate relation has not been clarified. We investigated the dynamic relationship between the Q-aT interval and heart rate in 10 patients with long QT syndrome and 11 control subjects using our original computer algorithm for the analysis of 24-hour Holter ECG recordings. The patients showed morphological T wave changes associated with heart rate changes during Holter recordings and these affected the Q-aT interval. The patients showed the following characteristics in the relationship between the major T wave peak and the RR interval: (1) a modestly decreased correlation between Q-aT and RR than in the control subjects (a median r value of 0.87 vs 0.93; P = 0.001); and (2) a steeper Q-aT/RR slope than in controls (a median slope of 0.24 vs 0.16; P < 0.05). Abnormal and variable T wave morphology in the long QT patients was closely related to a modestly decreased correlation between Q-aT and RR than in the control subjects. The steep Q-aT/RR slope might reflect unstable repolarization of the ventricle, which could act as a substrate for ventricular tachyarrhythmias.     

The Marker Channel: A Telemetric Diagnostic Aid

Vinterprétation des tracés ECG des patients porteurs de pacemakers sophistiqués est souvent difficile. De ce fait de tels pacemakers sont maintenant équipés de télémétrie restituant les données programmées. L'utiJisation d'un canal marqueur, les intervalles de détection, et de stimulation est particuliérement utile en ce sens, Il est ainsi possible d'obtenir un inventaire détaillé des événements en association à l'ECG en queiques minutes, et d'une précision telle qu'il n'est plus nécessaire à l'operateur de mémoriser les données du pacemaker. Le système est décrit, et quelques exemples sont discutés.     

Timing Markers Showing Pacemaker Behavior to Aid in the Follow-Up of a Physiological Pacemaker

In the present study a multiprogrammable, atriul synchronous, ventricular inhibited pacemaker (Enertrax) was used in six patients. This pacer makes it possible to evaluate pacemaker performance nonmvasively and facilitates the correct interprefation of the djfficult ECGs produced by these complex pacemakers.     

Cluster headache: a computerized analysis of 24 h Holter ECG recordings and description of ECG rhythm disturbances

Continuous ECG recording has been carried out for at least 24 h in 27 patients suffering from cluster headache. During the study a total of 84 attacks occurred in 25 of the 27 patients who took part. A computerized analysis of the heart rate changes accompanying attacks showed the following: (i) an increase in heart rate at the onset of attacks; the degree of this increase being dependent on the heart rate before attacks, (ii) a relative decrease in heart rate and increased variations in heart rate during attacks, (iii) a relative increase in heart rate at the end of attacks, and (iv) a relative decrease in heart rate after attacks. Five patients (18.5%) showed ECG rhythm disturbances: two frequent premature ventricular beats, one transient attacks of atrial fibrillation, one first degree atrio-ventricular block, and one patient sino-atrial block.     

A New Pacemaker for Monitoring Asystole and Prevention of Adams-Stokes Syndrome and Sudden Cardiac Death

Patients with suspected Adams-Stokes syndrome are examined by Holter monitoring. During the monitoring, there is the danger of syncopes occurring and there are even reports of sudden cardiac death. We therefore developed a pacemaker for cardiac arrest monitoring and the prevention of Adams-Stokes syndrome and sudden cardiac death, which has the following functions: (1) the longest escape interval of the pacemaker not exceeding the value at which syncope is induced is determined by the decline of the mean heart rate including the asystole to a certain threshold rate; (2) once the pacemaker escapes from the interval it continues pacing for a while at a physiological rate to allow recover from ischemias in organs or tissues; and (3) to prevent overdrive suppression to the heart, the pacing rate gradually declines and stops pacing until the next asystole. This pacemaker is useful not only in the diagnosis of Adams-Stokes syndrome but also in pharmacological and pathophysiological studies and in determining when pacing should cease.     

Usefulness of 1-Hour and 24-Hour Heart Rate Holter Inbuilt in New TX* Rate Adaptive Pacemakers

SERMASI S., ET AL.: Usefulness of 1-Hour and 24-Hour Heart Rate Holter Inbuilt in New TX* Rate Adaptive Pacemakers. The rate adaptive TX* pacemaker uses the evoked QT interval as an indicator of physiological demand. In order to obtain a rate adaptation close to physiological patterns we used in the past, in each patient, on the slope value and/or the T wave sensing window, controlling via exercise stress testing and Holter the results achieved. It was an expensive method, but the system produced effective rate responsive pacing. The new series of TX* pacemakers (Quintech 919 and Rhythmyx), beside the dynamic slope feature, are equipped with a 1-hour heart rate Holter (HRH) that can be used during effort without the need for manually recording the heart rate. In this mode TX* pacemakers calculate the average heart rate over 20-second periods and stores the values continuously for 1 hour. In addition, a 24-hour HRH is available, which calculates the average heart rate over 7.5-minute periods, showing heart rate trend during the last day prior to interrogation. Each HRH can be accessed by the programmer and printed out. Using four Quintech 919* and five Rhythmyx units, the inbuilt HRH proved its utility by making the heart rate adaptation checking procedure easier, faster, and more economic.     

Automatic Adjustment of Pacemaker Stimulation Output Correlated with Continuously Monitored Capture Thresholds: A Multicenter Study

Pacing threshold is affected by many factors. A pacing system able to confirm capture at each beat and automatically adjust its output close to the actual pacing threshold is highly desirable. This study evaluates the safety and efficacy of the Autocapture function of the Pacesetter Microny SR+. One hundred thirteen patients were recruited from 16 centers in 7 European countries and followed up for 1 year. All pacemakers were implanted with Pacesetter's low polarization, bipolar leads. The key feature of Autocapture is the immediate delivery of a 4.5 V safety backup pulse 62.5 ms after any ineffective ongoing low output pulse. Holter recordings confirmed total reliability of this feature without any exit block. The measured evoked response (ER) signal was stable over time. Acute and chronic pacing thresholds measured by VARIO and Autocapture tests correlated (r > 0.79) over the period of the study. The incidence of backup pulses was 1.1% during pacing. With Autocapture programmed ON, the overall total current consumption was 4.1 μA for VVI and 5.0 μA for VVIR pacing. Tbis study proved that the Autocapture safely and reliably regulates the pacemaker's output according to the prevailing threshold thus providing maximum patient safety and prolonging service life.     

A New Motion Responsive Pacemaker: First Clinical Experience with an Acceleration Sensor Pacemaker

A new accelerometer-based adaptive rate pacemaker (OEXCELVR^TM) was evaluated to investigate its behavior at nominal settings during treadmill exercise testing and postural changes. Eight patients with sinus rhythm were selected to compare intrinsic heart rate to sensor mediated rate. Throughout exercise treadmill testing, changes in the sensor mediated rate closely paralleled actual physiological changes. The Pearson product moment correlation of pacing rate with sinus frequency, calculated for all patients, was r = 0.82 (P = 0.001). Change in the patient's physical position resulted in immediate change in sensor rate, which corresponded appropriately to the type of position change and activity level. Average (± SD) pacing rate was 62.4 ± 2.7 beats/min supine; 67 ± 3.8 beats/min sitting; 69.8 ± 6.4 beats/min standing; 81.6 ± 8.7 beats/min slow walking; and 96.8 ± 1.3 beats/min fast walking. After 4 minutes of recovery, the average pacing rate dropped to 65 ± 3 beats/min. The interaction between the accelerameter and the pulse generator at nominal settings was accurate and infrequently required the use of its many programming options. The accelerometer sensor and pulse generator algorithm in this device during postural change and exercise resulted in physiological-like changes in sensor mediated heart rate.     

The Combined Use of Hysteresis and Holter Functions Improves Diagnosis and Therapy in Patients with Sick Sinus Syndrome

We used the Holter functions of an implantable pacemaker in 12 patients with sino-atrial disease suffering from Adam-Stokes attacks to analyze the effects of hysteresis programming. The basic pacing rate of 50 ppm combined with a programmed hysteresis value of 10 to 20 ppm led to a drastic reduction in competition between paced and spontaneous beats: the percentage of paced beats decreased from 20.1% without hysteresis to 1.4% using 10 ppm hysteresis and the switches from sense to pace decreased from 2.0% to 0.06%. On the other hand, with hysteresis, no decrease in either the exercise tolerance or general well-being of the patients was observed.     

The Role of Electrophysiologic Studies in the Management of Patients with Unexplained Syncope

We evaluated the frequency and type of electrophysiologic abnormalities in an unselected population of consecutive patients with unexplained syncope. Fifty patients were entered in the study; all had 24-hour dynamic electrocardiographs (Holter) recordings and underwent complete electrophysiological studies. An abnormal electrophysiologic study was found in 74% of the patients. Sinus node abnormality was observed in 30%, abnormal AV node function in 14%, long HV in 10%, block distal to H during rapid atrial pacing in 6%, paroxysmal supraventricular tachycardia in 12%, ventricular tachycardialfibrillation in 8%, and hypersensitive carotid sinus syndrome in 24%. There was no correlation between Holter and electrophysiologic study findings except for the presence of paroxysmal sustained supraventricular tachycardia. Based on clinical, Holter monitoring, and electrophysiologic findings, 38% were treated by antiarrhythmic drugs, 40% received permanent pacemakers, and. 22% were not treated at all. During follow-up (23 ± 13 months), 9 patients (18%) experienced recurrent syncope or death.     

A New Pacemaker Algorithm for Continuous Capture Verification and Automatic Threshold Determination: Elimination of Pacemaker Afterpotential Utilizing a Triphasic Charge Balancing System

A new pacemaker algorithm designed to automatically verify pacemaker capture and determine pacing threshold by detection of a stimulus evoked potential was studied in 20 patients undergoing permanent pacemaker implantation. To eliminate pacing stimulus afterpotential and detect an evoked response, a hardware feedback circuit and a software template matching algorithm were used to produce a triphasic charge-balanced pacing pulse. After charge balancing the pacing lead, a residual artifact is measured. A capture window is defined as the area integral of the first 24 msec of the evoked depolarization, and a capture threshold as one third the amplitude of the capture window. The maximum allowable residual artifact is one eighth the amplitude of the capture window. Once the stimulus afterpotential is eliminated and the evoked response detected, capture threshold is automatically and continuously determined and the algorithm adds a 0.8-V safety margin to the pacemaker output. This algorithm was run automatically and after simulated loss of capture, produced by manually decreasing pacer output below threshold, in the bipolar (13 patients) and unipolar (20 patients) pacing modes. In each patient loss of capture was immediately detected. The data were consistent (P = NS) between algorithm runs. During unipolar pacing the area integral of the first 24 msec of the evoked response was 412 +/- 137 versus 413 +/- 144 and the residual artifact 5.8 +/- 4.8 versus 8.1 +/- 7.5. The resulting ratio (signal/noise) of the two parameters was 150 +/- 141 versus 145 +/- 181. Automatically determined threshold was 0.69 +/- 0.43 V versus 0.69 +/- 0.42.(ABSTRACT TRUNCATED AT 250 WORDS)     

Voltage Dip in Pacemaker Battery Supply: A New Cause of Pacemaker Mediated Tachycardia

A new cause of pacemaker medialed tachycardia was observed in a patient equipped with a Vitatron® Quintech 931 DDD pacemaker. In this type of pacemaker the microprocessor is switched off during the atrial refractory period. Beyond the recommended replacemenl lime, the internal resistance of the battery may increase to such an extent that switching on and off the microprocessor may cause voltage dips. Those voltage dips are erroneously interpreted as P waves hy the atrial sensing amplifier, which may cause self-triggering of the pacemaker and initiate a pacemaker mediated tachycardia.     

Holter monitoring for 24 hours in patients with thromboembolic stroke and sinus rhythm diagnosed in the emergency department

It is well known that patients with ischemic stroke show ST-T abnormalities and various rhythm abnormalities on an electrocardiogram (ECG). The most commonly encountered rhythm abnormality is atrial fibrillation. It was recently shown that paroxysmal atrial fibrillation (PAF) is an important causative factor in patients with stroke. Detection of PAF is important in identifying the cause, prognosis, and treatment in patients with thromboembolic stroke. Investigators in the present study followed patients with thromboembolic stroke who had been admitted to the emergency department in sinus rhythm; 24-h Holter monitoring was used, and patients were assessed at referral and every 6 h for 24 h with ECG, which was used to detect rhythm disturbances, especially PAF. In 26 patients with stroke who came to the emergency department, acute thromboembolic stroke was diagnosed on the basis of magnetic resonance imaging; no rhythm abnormalities were noted on Holter monitoring. Eighteen patients were male and 8 were female (mean age: 66±13 y). Arrhythmia was identified on ECG in 3 patients (11%) and on 24-h Holter monitoring in 24 patients (92%). PAF was diagnosed in 3 patients (11%) on ECG and in 11 patients (42%) on Holter monitoring. In 2 patients, nonsustained ventricular tachycardia was detected only on Holter monitoring, which was found to be significantly superior to ECG for the detection of arrhythmias (P < .001). Investigators found no significant relationship between PAF and variables such as hypertension, diabetes, coronary artery disease, history of myocardial infarction, ST-T changes, and elevations in cardiac markers. However, a significant relationship (P < .01) was seen between nonsustained ventricular tachycardia and a history of myocardial infarction. No relationship was discerned between arrhythmia and stroke localization. Study results suggested that (1) PAF is a commonly diagnosed rhythm abnormality, and (2) Holter monitoring is superior to routine ECG for the detection of arrhythmias such as PAF in patients anticipated to have thromboembolic stroke with sinus rhythm.     

His Bundle Recordings Using Epicardial Pacing Wires: A New Technique

His bundle electrograms were recorded from the epicardial surface of the heart of nine dogs using temporary pacing electrodes. Simultaneous His bundle activity was recorded by the standard endocardial catheter technique. There was a close correlation between the AH times (r = 0.93) and HV times (r = 0.96) using both techniques. This new technique for studying His bundle activity is simple, requires no additional dissection during the performance of open heart surgery, and should be of value in diagnosing conduction system disturbances occurring in the perioperative period.     

Should Unipolar Leads Be Implanted in the Atrium? A Holter Electrocardiographic Comparison of Threshold Adapted Unipolar and High Sensitive Bipolar Sensing

The accuracy ofatrial sensing plays a central role in dual chamber pacing. Recent Holter electrocardiographic studies showed a high incidence of atrial malsensing. We investigated the efficacy of bipolar atrial sensing at high sensitivity compared to threshold adapted unipolar sensing. One h undred consecutive patients with identical dual chamber pacemakers and bipolar atrial leads were investigated. Mean and individual range of 40 unipolar and bipolar telemetered atrial potentials were calculated; sensing threshold was determined by a semiautomatic sensing test. Oversensing was investigated with the help of a muscle provocation test. Twenty-four-hour Holter monitoring was performed at the highest bipolar sensitivity as well as at a unipolar sensitivity of half the measured sensing threshold. Mean atrial potential was significantly lower during bipolar mode compared to the unipolar sensing configuration, 3.66 ± 1.75 versus 3.85 ± 1.62 mV, P = 0.02. The bipolar atrial potentials showed a higher individual range than the unipolar signals, 2.44 ± 2.62 versus 1.79 ± 0.92 mV, P < 0.01. Sensing threshold did not differ significantly, 2.76 ± 1.33 versus 2.67 ± 1.29 mV. Mean oversensing threshold was 1.21 mV at unipolar configuration, whereas oversensing could not be provoked at a bipolar sensitivity of 0.5 mV. The incidence of atrial undersensing was significantly higher at threshold adapted unipolar sensing compared to bipolar sensing at highest atrial sensitivity, 35% versus 22%, P = 0.04. Oversensing did not occur at bipolar sensing, but was observed in 56% of patients at unipolar mode. Thirty-two percent of patients showed both atrial undersensing and over- sensing at the unipolar sensing configuration. The muscle provocation test reached a sensitivity of 89% and a specificity of 95% in prediction of atrial oversensing during daily life. In conclusion, unipolar atrial potentials are more stable than bipolar ones. On the other hand, bipolar atrial sensing is less prone to the perception of myopotentials. Programming a high bipolar sensitivity significantly improves atrial sensing. Th us, bipolar leads should generally be implanted in the atrium.     

Sino-Atrial Dissociation: Evidence by Intracardiac Recordings in Man and by Microelectrode Studies on Isolated Rabbit Atrium

The electrophysiologic mechanisms of sinus dysfunction have recently been determined by direct recordings of the sinus node electrogram. The association of various degrees of abnormalities in the formation of the impulse within the sinus node and of sinoatrial conduction block, represents the pathophysiological substrate of the mechanism of sinus node dysfunction. The purpose of this work is to present clinical and experimental data supporting the concept of sinus node isolation. In our clinical case, the sinus node was probably intact despite aspects of sinus node dysfunction on the surface ECG. Sinus node electrograms were recorded with a sinoatrial conduction time of 100 ms (normal values in our laboratory: 83 ms +/- 38 ms). Atrial mapping demonstrated that the area depolarized by the sinus node involved a 2 cm2 zone surrounding it. This perisinusal activity could not be recorded on the surface ECG. Both exit and entry blocks in the sinus node were demonstrated. Our experimental data showed a total desynchronization between the electrical activity of the sinus node and that of the atrium under hypoxic conditions. Both types of cases demonstrated that an atrial dysrhythmia was coexisting with regular sinus activity. From these data we concluded that a sinus node free from any pathological involvement could be associated with severe symptoms of sinus node dysfunction on the surface ECG.