Biomedical subjects

B V Berkovits

Publications and source records attributed to B V Berkovits.

5 recordsLinked to original sources

PubMed1979

Programmed simultaneous biventricular stimulation in man, with special reference to its use in the evaluation of intraventricular reentry.

Programmed stimulation was alternatively performed exclusively from the right ventricular endocardium, exclusively from the left ventricular epicardium and simultaneously from both ventricles in 8 patients who did not have coronary artery disease or bundle branch block. A specially constructed QRS triggered pacemaker, (with a refractory period of 260 msec and an escape interval of 800 msec) connected to the right ventricular and left ventricular electrodes, was used to perform simultaneous biventricular stimulation. The latter had no untoward effects and was not more dangerous than exclusive right ventricular, or exclusive left ventricular, stimulation. In 3 patients, pacemaker-induced repetitive firing occurred during right and left ventricular pacing. Persistence of this phenomenon (in these 3 patients) during simultaneous biventricular stimulation is in keeping either with a microreentry occurring in the vicinity of the electrodes or with a macroreentry involving the bundle branches. A more precise evaluation of the reentry circuit requires that left ventricular pacing be performed from an endocardial (rather than from an epicardial) site. This study suggests that the pulse generator described in the present communication can be used to produce simultaneous atrial and ventricular activation (or pacing) by connecting one pole to an atrial electrode and the other pole to a ventricular electrode. This modality of stimulation can be effective in preventing or abolishing some types of reciprocating atrioventricular tachycardias.

Aged↗

PubMed1978

Hemodynamic consequences of atrioventricular and ventriculoatrial pacing.

The effect of atrial-ventricular versus ventricular pacing and contraction were studied in seven open-chest dogs. Cardiac output, left ventricular, left atrial, right atrial and pulmonary artery pressures were recorded. The right or left ventricular apical areas were consistently superior as ventricular pacing sites. Appearance of cannon A waves within the pre- or ejection period produced a significant decrease in left ventricular and systemic blood pressure, and cardiac output with a concomitant increase in right atrial, ventricular and pulmonary pressures. Prominent "v" waves were also observed during these periods. Reducing the basic driving cycle length from 400 to 300 msec caused a marked deterioration of all hemodynamic parameters with the appearance of mechanical alternans. Random VA conduction or ventricular pacing in the presence of complete AV and VA heart block appeared to offer a more favorable hemodynamic result than constant 1:1 VA conduction. It is concluded that maintenance of a physiologic AV interval permitting atrial contraction to appear outside of pre- or ejection period of ventricular systole is an important determinant or ventricular function during cardiac pacing.

Animals↗

PubMed1978

His bundle recordings in atrioventricular nodal alternating Wenchebach periods ending in 5:1 atrioventricular block coexisting with paroxysmal atrioventricular nodal block.

Atrioventricular nodal alternating Wenckebach periods ending in 5:1 atrioventricular block occurring during rapid atrial rhythms were explained by postulating the presence of block in three levels of the atrioventricular node. This pattern of conduction occurred in ten of 11 patients who either had received ouabain or verapamil (nine patients) or who had organic atrioventricular nodal disease (two patients). In contrast, this pattern of conduction occurred in only one of eight nonmedicated patients without organic atrioventricular nodal disease. The frequent association of this pattern with paroxysmal, tachycardia-dependent atrioventtricular nodal block suggested a similar, but not necessarily identical, mechanism. In conclusion, atrioventricular nodal alternating Wenckebach periods ending in 5:1 atrioventricular block, as well as paroxysmal atrioventricular nodal block, were only rarely the result of rapid atrial rates per se their occurrence indicating organic or pharmacologic effects on the atrioventricular node. Since both can be produced by carotid sinus pressure, further studies appear to be necessary to determine the role that vagal effects can have in their genesis.

Bundle of His↗

PubMed1975

Use of atrial and bifocal cardiac pacemakers for treating resistant dysrhythmias.

Several permanent cardiac pacing techniques have been utilized to control resistant cardiac arrhythmias. SA block, sinus arrest and intermittent ventricular tachycardia was controlled by the use of an atrial 'J' catheter and a rate programmable demand pacemaker. When these arrhythmias were associated with AV conduction delay they were managed with an AV sequential pacemaker with the additional insertion of a ventricular pacing lead. Appropriate adjustment of the AV sequential interval inhibited reciprocal AV or VA reentry thus controlling reciprocal tachycardia. Frequent ventricular premature systoles or intermittent ventricular tachycardia with in appropriately delayed sinus or subsidiary escape cycle lengths appear best managed by an AV sequential pacemaker by adjusting the atrial return cycle. Intractable atrial reentry tachycardias appear best managed by paired or rapid atrial stimulating pacemakers. Development of variable atrial rate, AV sequential and atrial return cycle activating pacemakers offer an effective control of resistant cardiac arrhythmias.

Adult↗

PubMedDate not supplied

[Electrophysiology of pacemakers by demand. Critical analysis].

The adequate interpretation of cardiac arrhythmias should be done in context with the clinical facts. In case of arrhythmias induced by pacemakers, it is essential to have detailed information about the characteristics of the electronic instrument. This paper shows, that only with precise information about the electrophysiological facts of a certain instrument, it is possible to diagnose the origin of an arrhythmia, its significance related to normal function or disfunction of the apparatus and the proper measures can be taken for correcting the disorder. Examples of clinical cases have been presented, and undoubtedly a growing improvement in the elaboration of the electronic instruments, will enrich, the already ample field of cardiac arrhythmias. All of it will lead to an undoubtful benefit for patients, medical personnel who are involved in the electric treatment of the disturbances in rhythm and conduction.

Arrhythmias, Cardiac↗