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Biomedical subjects

M D Falkoff

Publications and source records attributed to M D Falkoff.

32 records · Page 2Linked to original sources
PubMed1985

Oversensing by single-chamber pacemakers: mechanisms, diagnosis, and treatment.

Signals responsible for pacemaker oversensing may arise from the pacing system itself, P or T wave, concealed ventricular extrasystoles, skeletal muscle potentials, and distant electromagnetic fields. Oversensing is the most common cause of pacemaker pauses and a common clinical problem during follow-up of patients with implanted pulse generators. This article reviews the mechanisms and diagnosis of oversensing and the importance of multiprogrammability for its treatment.

Arrhythmias, Cardiac↗
PubMed1984

Programmability in DDD pacing.

Safe and reliable DDD pacemakers with multiple programming capabilities have now been developed. Certain programmable parameters are basic, including mode, voltage (or current) output, pulse width, sensitivity and refractory periods in each chamber. Upper rate response as well as low rate settings and A-V delays are equally important. In certain models, the ability to program the blanking period has proven quite useful. The interrelationship between all these functions will assure the smooth overall performance of these sophisticated devices.

Arrhythmias, Cardiac↗
PubMed1981

Interpretation of electrocardiograms produced by a new unipolar multiprogrammable "committed" AV sequential demand (DVI) pulse generator.

This paper describes our approach to the interpretation of electrocardiograms produced by a new unipolar multiprogrammable "committed" DVI pulse generator (Intermedics) during normal function. The arrhythmias engendered by this new DVI pacemaker may be better understood by conceptualizing the recycling mechanism in terms of a simple atrial pulse generator with two important qualification: 1) the ventricular stimulus obligatorily follows the atrial stimulus after 155 ms (AV sequential interval); 2) the pulse generator senses ventricular events (via the ventricular electrode) but recycles according to its atrial timing cycle (AA interval). These characteristics lead in turn to two important consequences: a) the QA interval (from the onset of a sensed QRS complex to the succeeding atrial stimulus) must be longer than the VA interval (from a ventricular stimulus to the succeeding atrial stimulus) by a period equal to or slightly greater than the AV sequential time. This may be considered to represent a form of hysteresis. b) the pacemaker refractory period always starts at the onset of an atrial cycle (AA interval( and therefore occurs after the delivery of an atrial stimulus or after a sensed ventricular event. The above characteristics may cause pacemaker stimuli to fall within the P wave, PR interval, QRS, ST segment and the ascending limb of the T wave during normal function of the pulse generator. Superficially, these peculiarities resemble malfunction and may be quite befuddling but they all occur predictably according to the electronic design of the pulse generator.

Arrhythmias, Cardiac↗
PubMed1980

Sources of error in the determination of output voltage of pulse generators by pacemaker system analyzers.

The use of threshold or pacemaker system analyzers with widely different characteristics has introduced potential sources of error in the determination of the output voltage of pulse generators. This is further compounded by the availability of pulse generators with diverse waveform configurations and programmability capabilities. Because of this non-uniformity, the physician must have some rudimentary knowledge of waveform characteristics and appreciate the limitations of threshold or pacemaker system analyzers to avoid the unnecessary replacement of normally-functioning pulse generators.

Electric Power Supplies↗
PubMed1980

Characterization of pacemaker arrhythmias due to normally functioning AV demand (DVI) pulse generators.

Normally functioning DVI pulse generators with different electronic characteristics may cause complex cardiac arrhythmias that must not be interpreted as pacemaker malfunction. When there is no refractory period after the atrial output, a DVI pulse generator may deliver atrial pacemaker impulses at irregularly shortened intervals and produce an increase in the atrial pacemaker rate compared with the programmed free-running AV sequential rate. Theoretically this variation of the atrial cycle length can occur only within a well-defined range that represents the difference between the ventricular and atrial output escape intervals. In reality, the interplay of the spontaneous sinus rate, duration of AV conduction, time of sensing the ventricular electrogram in relation to the surface QRS complex, and the programmed AV sequential time all influence the atrial pacemaker rate. DVI pulse generators may also create interesting arrhythmias such as pseudopseudofusion beats (delivery of an atrial spike within the QRS complex), double pseudofusion beats, and double pacemaker impulses within the QRS complex according to the electrophysiologic circumstances and specifications of the pulse generator.

Arrhythmias, Cardiac↗
PubMed1977

Inhibition of bipolar demand pacemaker by diaphragmatic myopotentials.

This report describes inhibition of a normally functioning bipolar demand pulse generator by diaphragmatic myopotentials. Transient pacemaker suppression occurred repeatedly with deep respiration, straining, the Valsalva maneuver, coughing, sneezing and laughing. When the magnet was applied, none of these maneuvers inhibited the pacemaker. Extensive investigations ruled out an intermittent electrode problem such as a wire fracture or insulation break. Sensing of diaphragmatic myopotentials should be considered in the differential diagnosis of unexplained pacemaker pauses.

Action Potentials↗