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Biomedical subjects

R A Heinle

Publications and source records attributed to R A Heinle.

At least 37 records · Page 2Linked to original sources
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↗
PubMed1979

Familial cardiac myxoma: emphasis on unusual clinical manifestations.

This report describes familial cardiac myxoma involving parent and child. The familial occurrence of this condition, previously reported in four other families, underscores the necessity of screening all direct members of the family by echocardiography once the diagnosis of cardiac myxoma is made. Each patient presented with unusual clinical manifestations. The father, who had a right atrial myxoma associated with an atrial septal defect and mitral valve prolapse, presented with findings highly suggestive of paradoxical embolism. The daughter, who had an infected right ventricular myxoma, was initially treated for valvular subacute bacterial endocarditis before the diagnosis was made.

Adult↗
PubMed1978

Inapparent double puncture of the femoral artery and vein. An important complication of temporary cardiac pacing by the transfemoral approach.

An important complication of temporary cardiac pacing by the transfemoral approach. This report describes three cases of inapparent double puncture of the femoral artery and vein as a complication of the transfemoral approach for temporary cardiac pacing. This complication may lead to the passage of a pacing catheter to the right ventricle by way of the femoral artery and vein and may remain undiagnosed until the rigid outer sheath of the introducer set is withdrawn over the pacing catheter. Therefore, we recommend immediate withdrawal of the rigid outer sheath as soon as the catheter lies freely in the iliac vein or the inferior vena cava. If double puncture has occurred, arterial blood will leak around the pacing catheter. Control of arterial bleeding by local compression should not be attempted without removal of the pacing catheter.

Cardiac Pacing, Artificial↗
PubMed1978

The noise sampling period: a new cause of apparent sensing malfunction of demand pacemakers.

Two patients with Omni-Stanicor pulse generators presented an apparent sensing problem characterized by intermittent reversion to fixed-rate pacing only during atrial fibrillation with a very rapid ventricular rate. Every fixed-rate cycle contained two unsensed beats. The first unsensed beat fell in the noise sampling period (the last 1/6 of the pacemaker refractory period) and, therefore, disabled the demand function of the pulse generator for a single timing cycle. The presence of two consecutively unsensed beats within one timing cycle (automatic or escape interval) during tachycardia suggests normal function of the noise sampling period of this particular pulse generator, rather than a true sensing problem. The diagnosis becomes evident if the sensing problem disappears when abbreviation of the refractory period occurs by reprogramming the pulse generator at a higher rate.

Aged↗
PubMed1978

Unusual complication of bifascicular block during surgery under general anesthesia.

This report describes the occurrence of Mobitz type II AV block during surgery under general anesthesia in a patient with apparently uncomplicated right bundle branch and left anterior fascicular block (RBBB and LAH). Although prophylactic pacing is not usually recommended in uncomplicated RBBB and LAH, the events in this case suggest that this abnormality may not always be benign during surgery. Continuous monitoring is essential and emergency equipment for temporary pacing should be readily available near the operating and recovery rooms.

Aged↗
PubMed1978

Periodic pacemaker spike attenuation with preservation of capture: an unusual electrocardiographic manifestation of partial pacing electrode fracture.

This report describes the electrocardiograms of a patient with an intermittent electrode fracture presenting with periodic attenuation of the pacemaker spike without loss of ventricular capture. There was infrequent prolongation of the spike-to-spike interval probably because the pulse generator interpreted random false signals as interference and reverted to its fixed-rate mode. These observations add to the spectrum of electrocardiographic abnormalities of electrode malfunction.

Aged↗
PubMed1978

Reprogramming of implanted pacemaker following external defibrillation.

This report describes reprogramming of a pulse generator consequent to cardiac defibrillation. Analysis of the explanted pulse generator revealed normal function. We tested the electrical properties of several defibrillators and our studies suggest that erratic electrostatic discharges at the time of paddle application before defibrillation may create a signal sequence capable of reprogramming the particular pulse generator by activating either the reed switch or internal electronics.

Electric Countershock↗