PubMed Health⌕ Search

Biomedical subjects

S S Barold

Publications and source records attributed to S S Barold.

At least 109 records · Page 6Linked to original sources
PubMed1991

Repetitive reentrant and non-reentrant ventriculoatrial synchrony in dual chamber pacing.

Repetitive retrograde ventriculoatrial (VA) conduction in patients with dual chamber pacemakers may cause two forms of VA synchrony. (1) Endless loop tachycardia (pacemaker-mediated tachycardia) or repetitive reentrant VA synchrony occurs when the pacemaker senses retrograde P waves. Appropriate programming can prevent pacemaker reentrant tachycardia in almost all cases. However, the measures used to control tachycardia may themselves create new problems. (2) AV desynchronization arrhythmia or repetitive non-reentrant AV synchrony occurs when the pacemaker does not sense retrograde P waves. In this form of VA synchrony, the atrial stimulus is ineffectual because it falls in the atrial myocardial refractory period generated by the preceding unsensed retrograde P wave. A long atrioventricular interval and a relatively fast lower rate (or sensor-driven rate with DDDR pacing) favor the development of AV desynchronization arrhythmia and its unfavorable hemodynamic consequences.

Cardiac Complexes, Premature↗
PubMed1988

Magnet unresponsive pacemaker endless loop tachycardia.

Endless loop tachycardia is a well-known complication of DDD pacing and is almost invariably terminated by conversion to the asynchronous DOO mode upon application of a magnet over the pulse generator. Occasionally magnet application is ineffectual because the ventriculoatrial (VA) synchrony of endless loop tachycardia is converted directly or indirectly to an atrioventricular (AV) desynchronization arrhythmia, another form of VA synchrony. This occurs when a paced ventricular beat engenders an unsensed retrograde P wave and the continual delivery of an ineffectual atrial stimulus during the atrial myocardial refractory period creates self-perpetuating VA synchrony. Upon magnet removal, AV desynchronization arrhythmia reverts immediately to endless loop tachycardia. In the absence of access to programmers, magnet unresponsive endless loop tachycardia can be easily and reliably terminated by chest wall stimulation through inhibition of the ventricular channel of the DDD pulse generator.

Cardiac Pacing, Artificial↗
PubMed1988

Termination of ventricular tachycardia by chest wall stimulation during DDD pacing. A report of two cases.

This report describes the use of chest wall stimulation (CWS) for the termination of ventricular tachycardia in two patients with dual chamber pulse generators functioning in the DDD mode. Rapid CWS induced burst ventricular pacing when CWS was selectively sensed by the atrial channel, whereupon the pulse generator triggered its ventricular output. In this way, by programming the pulse generators to the maximum upper rate, this CWS technique produced burst ventricular pacing at a rate of 175 to 180/minute that successfully terminated ventricular tachycardia in both patients. The same CWS technique also initiated ventricular tachycardia by burst ventricular pacing. This CWS technique may be useful for the termination of relatively slow ventricular tachycardia in patients with DDD pulse generators when the maximum rate of ventricular pacing cannot be otherwise increased.

Aged↗
PubMed1988

Pacemaker endless loop tachycardia: termination by simple techniques other than magnet application.

PURPOSE: Pacemaker endless loop (or reentrant) tachycardia (ELT) is often terminated by conversion to the asynchronous mode of pacing by simply placing a magnet over the implanted atrial tracking (DDD or VDD) pacemaker. We investigated three other simple methods of ELT termination--chest wall stimulation (CWS), provocation of myopotential oversensing, and chest thumping--that may be useful when the arrhythmia is unresponsive to magnet application or a magnet is unavailable. PATIENTS AND METHODS: A modified CWS technique using an external pulse generator (pulse width = 40 msec) ordinarily used for transcutaneous cardiac pacing was tested in 74 patients (40 with unipolar and 34 with bipolar DDD devices). CWS inhibited the ventricular channel of all DDD pacemakers easily and reliably. CWS was then applied during ELT in 20 patients (10 with unipolar and 10 with bipolar DDD devices). Provocation of myopotential oversensing by the ventricular channel was attempted during ELT in 10 patients with unipolar DDD pacemakers. Chest thumping was tried during ELT in six patients. RESULTS: CWS by the modified technique terminated ELT in all patients in whom the arrhythmia was induced. Myopotential oversensing resulted in successful ELT termination in six of the 10 patients. ELT was successfully terminated by chest thumping in four of six patients. CONCLUSION: These simple techniques provide effective ways of ELT termination other than magnet application, and may be easily applied by physicians unfamiliar with the complexities of contemporary DDD pacemakers and their programmers.

Cardiac Pacing, Artificial↗
PubMed1988

Electrocardiographic manifestations of the rapid recharge function of pulse generators after sensing.

In this report, we present our observations in three patients with Medtronic Spectrax VVI pulse generators that exhibited unusually clear electrocardio-Spectrax VVI pulse generators that exhibited unusually clear electrocardiographic artifacts, due to the rapid recharge function upon sensing. Although many contemporary pulse generators contain rapid recharge circuits operative after the delivery of a pacemaker stimulus, only certain Medtronic Spectrax pulse generators also possess a rapid recharge capability after sensing. Rapid recharge upon sensing may produce electrocardiographic deflections that should not be misinterpreted as pacemaker malfunction.

Electrocardiography↗
PubMed1988

Resetting of DDD pulse generators due to cold exposure.

We encountered resetting of three DDD pulse generators to the VVI mode, one at the time of implantation and two others just before implantation, and we believe this resulted from cold exposure during shipment. Consequently we analyzed the effect of cold exposure on five lithium-powered DDD pulse generators from different manufacturers. Cold exposure caused resetting of three of the five DDD pulse generators to the VVI mode. Only one of the reset pulse generators responded to application of the magnet by conversion to the asynchronous (VOO) mode, while the other two remained in the VVI mode. All DDD pulse generators should be routinely interrogated before implantation. If found to be reset, the likelihood of cold exposure is very high and the pulse generator can generally be reprogrammed to the DDD mode. The absence of a magnet response in reset DDD pulse generators appropriately inhibited and functioning in the VVI mode should not be interpreted as component failure when no output is observed.

Cold Temperature↗
PubMed1987

Cephalic vein guide wire technique for implantation of permanent pacemakers.

This report describes a modified cephalic vein guide wire technique for the implantation of permanent pacemakers. The procedure was attempted in 11 patients only when pacing leads could not be passed directly into the exposed cephalic vein. Eight bipolar DDD (two leads), two unipolar DDD, and one bipolar VVI (one lead) pulse generators were implanted successfully, with only one relatively minor complication. The cephalic vein guide wire technique provides easy access to the subclavian vein and may allow implantation of most single- and dual-chamber pacemakers with only a cephalic vein cutdown.

Aged↗
PubMed1987

Hyperkalemia-induced failure of atrial capture during dual-chamber cardiac pacing.

This report describes hyperkalemia-induced failure of atrial capture associated with preservation of ventricular pacing in a patient with a dual-chamber (DDD) pacemaker. This differential effect on atrial and ventricular excitability during cardiac pacing correlates with the well known clinical and experimental observation that the atrial myocardium is more sensitive to hyperkalemia than is the ventricular myocardium.

Aged↗