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Biomedical subjects

D L Hayes

Publications and source records attributed to D L Hayes.

At least 109 records · Page 6Linked to original sources
PubMed1989

Effects of extracorporeal shock wave lithotripsy on single chamber rate response and dual chamber pacemakers.

This study evaluated effects of extracorporeal shock wave lithotripsy on four models of Medtronic implantable cardiac pacemakers. In vitro testing consisted of: (1) unsynchronized pacemaker strapped on the patient with extracorporeal shock synchronized to the patient's native heart rate; and (2) pacemakers suspended alone in water 6 inches from the focal point, synchronizing the extracorporeal shock to pacemaker output. Unsynchronized shocks affected each model of pacemaker differently, i.e., single chamber constant rate pacemakers experienced extended periods of inhibition for more than three pacing cycles while activity-triggered rate response pacemakers exhibited rate increases to the upper rate setting. Dual chamber synchronous pacemakers exhibited intermittently a 59% decrease and a 20% increase in ventricular rate due to inhibition and triggering, respectively, from shock oversensing. Synchronized shocks did not alter the rate of single chamber constant rate pacemakers, but did cause the rate to increase to the upper rate setting for activity-triggered rate response pacemakers. The shock was synchronized to the initial atrial output from the dual chamber pacemaker and caused frequent inhibition of the ventricular stimulus when the ventricular-safety-pace (VSP) feature was programmed off. Programming VSP on reduced the incidence of ventricular inhibition resulting in near normal pacemaker operation. There was neither observable damage to pacemaker components nor spurious reprogramming of pacemaker parameters during the tests. Our studies with one manufacturer's pacemakers suggests that lithotripsy shock effects on implantable pacemakers can be tolerated provided: (1) the single chamber pacemaker is programmed to the demand constant rate modality; (2) the dual chamber pacemaker is programmed to VSP on or to the VVI mode; and (3) the pacemaker distance to the focal point is greater than 6 inches.(ABSTRACT TRUNCATED AT 250 WORDS)

Equipment Design↗
PubMed1989

A novel approach to atrial endocardial pacing.

We describe a patient who had tricuspid valve replacement and in whom dual-chamber pacing was accomplished by using a ventricular epicardial lead and by placing an atrial endocardial lead through the wall of the atrial appendage and positioning the tip against the endocardial surface of the atrial appendage. A ligature was placed around the atrial appendage where the lead passed through the wall of the right atrial appendage. This obviated the need for a second procedure to place the atrial lead in a transvenous fashion. After 5 years of follow-up the patient continues with normal DVI pacing.

Aged↗
PubMed1988

A shorter hospital stay after cardiac pacemaker implantation.

In an effort to shorten the hospital stay after implantation of a permanent cardiac pacemaker, some physicians have begun performing pacemaker implantation on an ambulatory basis. To assess the potential safety of shortening the duration of hospitalization after pacemaker implantation, we reviewed the complications that occurred in 100 consecutive patients after pacemaker implantation and noted the time after the implantation when the complications occurred. In our study group, all complications that necessitated invasive intervention occurred within 24 hours after the pacemaker implantation. Complications that necessitated noninvasive programming occurred as long as 72 hours after implantation, and all could have been safely corrected at the time of follow-up had the patient been dismissed at the 24-hour period. Although we do not believe that ambulatory pacemaker implantation should be routinely implemented at this time, the practice of dismissing patients at 24 hours after pacemaker implantation and scheduling subsequent outpatient follow-up seems to be safe and effective.

Adolescent↗
PubMed1988

Can transcutaneous electrical nerve stimulation be safely used in patients with permanent cardiac pacemakers?

In 51 patients who had 20 different models of permanent cardiac pacemakers, we conducted transcutaneous electrical nerve stimulation studies at four anatomic sites--the lumbar area, cervical spine, left leg, and lower arm area ipsilateral to the pacemaker. With a mean stimulation of 24.7 Hz, no episodes of interference, inhibition, or reprogramming of the pacemakers occurred. The proximity of the stimulation site to the pulse generator had no effect. We did not study electrodes placed parallel to the pacemaker electrode vector, a position that has been of concern to others and that should probably be avoided until proved safe. On the basis of our findings, we believe that most patients with permanent cardiac pacemakers can safely undergo transcutaneous nerve stimulation.

Adult↗
PubMed1987

DDD pacing: clinical considerations.

DDD pacemakers offer a physiologic form of pacing for selected patients by incorporating atrioventricular synchrony over a wide range of atrial rates. Selection of a patient for DDD pacing necessitates a thorough knowledge of the individual functions of the DDD pacemaker, the limitations of DDD pacing, and the patient's own electrical and physiologic needs. Continuing developments in cardiac pacing include further reduction of the possibility of pacemaker-mediated tachycardia, increased matching to metabolic needs, and advancement of telemetric technology and electrophysiologic testing.

Adolescent↗
PubMed1987

Activity-mode cardiac pacing: clinical considerations.

In the past, pacemaker candidates with "chronotropic incompetence" or chronic atrial arrhythmias have been treated with fixed-rate cardiac pacing. During physical exertion, however, increased cardiac output is often limited by this fixed rate. A physiologic pacemaker that increases the cardiac pacing rate as a response to physical activity is now available. The benefits of this pacemaker are increased heart rate during physical activity and increased exercise tolerance.

Cardiac Output↗
PubMed1987

Effect of 1.5 tesla nuclear magnetic resonance imaging scanner on implanted permanent pacemakers.

Patients with a permanent pacemaker are currently restricted from diagnostic nuclear magnetic resonance (NMR) imaging because of potential adverse effects on the pacemaker by the magnet. Previous work has shown that NMR imaging will result in asynchronous pacing of the pulse generator within a given distance of the magnet. The radiofrequency signal generated by the system may also result in rapid cardiac pacing, which may have deleterious effects. This study utilized a 1.5 tesla unit in an in vivo laboratory animal to evaluate the unit's effects on eight different pulse generators from two manufacturers. All pacemakers functioned in an asynchronous mode when placed within a certain distance of the magnet. In addition, transient reed switch inhibition was observed. Seven of the eight pulse generators paced rapidly when exposed to the radiofrequency signal and there was a dramatic decrease in arterial blood pressure. Whether effective rapid cardiac pacing would occur could not be predicted before exposure to the magnetic resonance unit. Nuclear magnetic resonance imaging with high magnetic fields in patients with a pacemaker should continue to be avoided until the mechanism of the rapid cardiac pacing can be further delineated and either predicted or prevented.

Animals↗
PubMed1986

The effects of magnetic resonance imaging on implantable pulse generators.

The effects of magnetic resonance imaging were assessed on four dual chamber and two single chamber pulse generators. The tests were performed with a resistive, water-cooled magnet operating at 0.15 T. The 6.4-MHz radiofrequency (RF) field was operated at a maximum power of 1,000 watts with a period adjusted from 130 to 500 ms. Reed switch closure occurred in all six pulse generators tested when placed near the entrance of the magnetic resonance imaging scanner, and the generators reverted to asynchronous operation unless programmed to the "magnet off" mode. None of the pulse generators exhibited any alterations in programmed parameters or in the ability to be reprogrammed after RF pulsing. When the RF field was turned on, there was no change in the asynchronous paced cycle length in four pulse generators; however, during RF scanning there was rapid cardiac stimulation at the RF pulse period in one single chamber and one dual chamber pulse generator.

Animals↗
PubMed1985

Sinus node dysfunction in pediatric and young adult patients: treatment by implantation of a permanent pacemaker in 39 cases.

To examine the clinical course of sinus node dysfunction that necessitates permanent pacing in the pediatric and young adult populations, we studied the records of the 39 patients 40 years of age or younger (mean age, 23 years) who underwent implantation of a permanent pacemaker for treatment of this disorder at our medical center between 1960 and 1983. The tachycardia-bradycardia syndrome was the most common rhythm disturbance, and syncope was the most frequent initial symptom. All symptomatic patients noted resolution of symptoms after pacemaker implantation. Twenty-five of the 39 patients (64%) had associated cardiovascular disease, most commonly transposition of the great arteries. In each of the 11 patients with this anomaly, sinus node dysfunction developed after a surgical procedure for correction of the defect. Of the total patient population, 20 patients (51%) had previously undergone a cardiac operation. The mean interval between pacemaker implantation and the previous operation was 105 months. After a mean follow-up of 50.5 months, the patients with no obvious underlying heart disease have done well. Each of the eight patients who have died had underlying cardiovascular disease. None of the deaths was thought to be pacemaker related. Sinus node dysfunction should be considered in the differential diagnosis of young patients with syncope or dizziness, especially if they have undergone a reparative cardiac surgical procedure. If symptomatic sinus node dysfunction is confirmed, permanent pacing is an effective therapeutic modality. In the absence of associated heart disease, the prognosis seems to be excellent.

Adolescent↗
PubMed1985

Cardiac arrhythmias in patients with surgical repair of Ebstein's anomaly.

Preoperative, perioperative and postoperative arrhythmias in 52 consecutive patients who underwent operation for Ebstein's anomaly were reviewed. There were 25 male and 27 female patients (mean age 18 years, range 11 months to 64 years). Thirty-four patients had one or more documented arrhythmias preoperatively (18 had paroxysmal supraventricular tachycardia, 10 had paroxysmal atrial fibrillation or flutter, 13 had ventricular arrhythmia and 3 had high grade atrioventricular block). Seven patients without documented arrhythmias had a history typical of tachyarrhythmias. During the perioperative and early postoperative periods, 14 patients had atrial tachyarrhythmias and 8 had ventricular tachycardia or ventricular fibrillation. There were seven deaths between day 1 and 27 months after operation. Five of these deaths were sudden (all in male patients, aged 12 to 34 years), and four of the patients had had perioperative ventricular tachycardia or ventricular fibrillation. One patient was taking one antiarrhythmic agent and another patient was taking two at the time of sudden death. Of the 18 patients with paroxysmal supraventricular tachycardia and 9 patients with paroxysmal atrial fibrillation or flutter preoperatively who were followed up for a mean of 40 and 36 months, respectively, 22 and 33% continued to have symptomatic tachycardia. Of the 11 patients (mean age 9 years) without preoperative documentation or symptoms of arrhythmia, follow-up data were obtained (range 1 to 144 months, mean 31) in 9 patients. None died suddenly or developed symptomatic arrhythmia.

Adolescent↗
PubMed1985

Bipolar tined polyurethane ventricular lead: a four-year experience.

With the advent of polyurethane as an insulating material for permanent pacemaker leads, concern has arisen over the integrity and long-term durability of polyurethane-insulated pacing leads. Specific concern has arisen over particular bipolar tined polyurethane ventricular leads. We have assessed our 4-year experience with this lead. This experience involves two groups of patients, those with leads manufactured before a certain date and those with leads manufactured at a later date. In the first group (judged to be at increased risk) the failure rate was 8.8%, and in the second group (judged not to be at increased risk) the rate was 3.9%. Lead failure occurred at an average of 17.5 months in the first group. Adequate follow-up on the second group is not available to determine whether or not the failure rate may eventually be as high as that in the early group. Actuarial analysis suggests that survivorship free of lead failure is probably not significantly different in the two groups. This experience points out the need for determining lead failure rates, identifying optimal lead design and configuration, and establishing a lead registry or mechanism by which the integrity of various pacing leads can be evaluated.

Electrocardiography↗
PubMed1985

Update on infections involving permanent pacemakers. Characterization and management.

From January, 1974, to December, 1983, 75 patients with infections related to permanent pacemakers were successfully treated. Demographic characterization, mode of presentation, types of infecting organisms, potential predisposing factors, significance of a retained infected pacemaker lead, and various medical and surgical treatment methods were analyzed. Likely infecting organisms depended on the mode of presentation and the time of the infection. Dermatologic diseases accounted for a significant number of secondary infections. Removal of the entire infected pacing system was required for eradication of infection in 74 of 75 patients. In 31 patients, the infected system was removed at the same time that the new system was implanted. In 26 patients, a two-stage procedure was used that included a period of temporary pacing between explantation of the old system and implantation of the new. No difference in complications or incidence of reinfection was found between these two groups. Infections occurring within 2 weeks after operation accounted for 15% of the cases. In these patients, Staphylococcus aureus was the most common organism. In patients with later infections, Staphylococcus epidermidis was the most common.

Adult↗
PubMed1984

Stability of AV conduction in sick sinus node syndrome patients with implanted atrial pacemakers.

Single-chamber atrial pacing is effective in the management of sinus node dysfunction, subject to the uncertainty of long-term atrioventricular conduction. Despite the accepted observation that many patients with sinus node dysfunction also have atrioventricular conduction disease, data do not exist on the development of atrioventricular block in those patients with permanent single-chamber atrial pacing. Of 70 patients who received single-chamber atrial pacing from 1967 to 1982 (mean duration of pacing was 33 months), only two patients of 58 (3.4%) of those with sinus node dysfunction developed atrioventricular (AV) block--after 14 months in one patient and after 23 months of successful atrial pacing in the other. None of the 12 patients paced for tachyarrhythmia management developed AV block. Of the 70 patients, 37 had assessment of AV conduction by incremental atrial pacing at the time of implant and 20 patients underwent atrial pacing on the basis of surface ECG and clinical judgment. Electrophysiologic studies were conducted only in those patients being paced for control of supraventricular arrhythmias. Only 5 of the 70 patients required conversion to ventricular pacing for technical difficulties; three of these conversions occurred in the early 1970's before the advent of atrial tined or J leads; one was for irreparable lead fracture and only one occurred in a patient with a newer design atrial lead. In conclusion, progression to AV block in patients with permanent atrial pacing is uncommon; formal electrophysiologic studies are necessary mainly in patients with supraventricular arrhythmias; and in the majority of patients, AV conduction can be assessed at the time of implant. Continued improvement in atrial leads should make atrial pacing even more successful.

Adult↗
PubMed1984

Platypnea-orthodeoxia: clinical profile, diagnostic workup, management, and report of seven cases.

Platypnea-orthodeoxia is a rare and poorly understood syndrome of orthostatic accentuation of a right-to-left shunt, usually across a patent foramen ovale. The syndrome is most commonly recognized in patients with a history of a major pulmonary disorder such as pneumonectomy, recurrent pulmonary emboli, or chronic lung disease. Pulmonary artery pressures are typically normal. The physiologic mechanism is unknown. We recommend that initial assessment consist of measurement of blood gases with the patient in the supine and upright positions. Orthostatic desaturation should prompt further investigation. A definitive diagnosis can most easily be obtained by tilt-table two-dimensional echocardiography with peripheral venous contrast medium. The shunt can be localized at the atrial level and directly visualized and semiquantitated. The decision about surgical closure of the patent foramen ovale is based on the degree of clinical disability. Because a significant shunt is manifest only in the upright position, astute clinical suspicion is of paramount importance for proper diagnosis. Increased awareness of this syndrome and ease of echocardiographic diagnosis will facilitate recognition of this potentially treatable cause of orthostatic hypoxia.

Cardiac Catheterization↗
PubMed1984

Importance and long-term utility of a multiparameter programmable pulse generator.

Almost all pacemakers currently implanted in patients in the United States are now capable of some degree of noninvasive programmability. Although programmability seems to be a very useful feature and allows flexibility in the patient's pacemaker system, the use of programmability in the late follow-up period has not been well substantiated. We compare the use of programmability in the early and late postoperative periods in 100 consecutive patients who received a multiparameter programmable pulse generator. Programmability is definitely a desirable feature, particularly for alterations in rate, pulse width, and sensitivity.

Adolescent↗
PubMed1984

Changing experience with dual chamber (DDD) pacemakers.

Dual chamber (DDD) or "universal" pacemakers have had a significant impact on the advancement of artificial pacemakers by providing a more physiologic approach to cardiac pacing. However, with the early generation of DDD pacemakers (pacemakers that sense and pace in both the atrium and the ventricle), a significant number of patients experienced pacemaker-mediated tachycardia because intact ventriculoatrial conduction was sensed in the atrium and a reentrant tachycardia was induced. Newer generation DDD pacemakers have provided longer atrial refractory periods, which should correct this problem. In this study the first and second years of a 2 year experience with DDD pacemakers were compared to determine if the newer generation devices have allowed maintenance of pacing in the DDD mode as opposed to reprogramming to some alternate mode because of pacemaker-mediated tachycardia or other pacing problems. The results showed a significant decrease in pacemaker-mediated tachycardia during the second year and continuation of pacing in the DDD mode in a higher percent of patients. This improvement is attributed to improvement in the pulse generator as well as better patient selection.

Adult↗