Biomedical subjects

Douglas Cameron

Publications and source records attributed to Douglas Cameron.

5 recordsLinked to original sources

PubMed2006

Cardiac electrophysiological consequences of neuromuscular incapacitating device discharges.

OBJECTIVES: The purpose of this study was to evaluate the cardiac consequences of neuromuscular incapacitating device (NID)/stun gun discharge in an experimental model. BACKGROUND: The large-voltage electrical discharges from NIDs have been suggested to pose a risk for triggering cardiac arrhythmias. METHODS: Intracardiac catheters and blood pressure transducers were inserted before the application of NID discharges in six anesthetized pigs. Two different commercially available models (NID-1 and NID-2), two different vectors of discharges (thoracic: parallel to the long axis of the heart on the chest wall, and nonthoracic: away from the chest, across the abdomen), and two different durations of discharge (5 and 15 s) were tested. The effect of simulated adrenergic stress using epinephrine was also evaluated. RESULTS: We studied a total of 150 discharges to 6 pigs; 74 of these discharges resulted in stimulation of the myocardium, as documented by electrical capture (mean ventricular rate during stimulation and capture, 324 +/- 66 beats/min). Of the 94 thoracic discharges, 74 stimulated the myocardium, compared with none from 56 nonthoracic discharges (p < 0.0001). During 16 discharges with epinephrine, there were 13 episodes of stimulation of the myocardium, of which 1 induced ventricular fibrillation and 1 caused ventricular tachycardia. Thoracic discharges from NID-1 were more likely to stimulate the myocardium than those from NID-2 (98% vs. 54%, p = 0.0007). CONCLUSIONS: In an experimental model, NID discharges across the chest can produce cardiac stimulation at high rates. This study suggests that NIDs may have cardiac risks that require further investigation in humans.

Animals↗

PubMed2004

Radiofrequency catheter ablation of a posteroseptal accessory pathway along the morphologic tricuspid valve in a patient with congenitally corrected transposition of the great arteries and complete atrioventricular block.

We report a patient with Congenitally Corrected Transposition of the Great Arteries, complete atrioventricular block and a posteroseptal accessory pathway across the morphologic tricuspid valve. Ablation of the accessory pathway was performed for her symptomatic palpitations.

Abnormalities, Multiple↗

PubMed2004

Inappropriate therapy from a defibrillator complicating transcoronary ablation of septal hypertrophy in a patient with hypertrophic obstructive cardiomyopathy.

This case report describes a patient with obstructive hypertrophic cardiomyopathy who received therapy inappropriately from his implanted defibrillator, subsequent to transcoronary alcohol ablation for septal hypertrophy (TASH). Widening of the intracardiac electrogram postablation resulted in "double counting" of the intrinsic ventricular electrogram by the device and inappropriate tachycardia detection.

Atrial Fibrillation↗

PubMed2003

Atrial evoked response integral for automatic capture verification in atrial pacing.

Beat-by-beat Autocapture is currently limited to operation in the ventricle with bipolar leads. The authors investigated the integral of the negative-going portion of the atrial evoked response integral (AERI) as a potential resource for verification of atrial capture. Intracardiac electrogram signals were collected from 59 patients (ages 67.8 +/- 15.1 years) with bipolar, low polarization atrial leads. The signals were collected over a mean period of 6.1 months (minimum 4 days) after lead implantation. St. Jude Medical Affinity pulse generators were used to perform automatic capture threshold tests while the electrogram signals were recorded by a Model 3510 programming device. These signals were transferred to a personal computer in digital form for later analysis. The AERI was calculated at each programmable pacing voltage until capture was lost. The difference between the polarization integral at loss of capture and evoked response integral with successful capture was sufficient to justify enabling the atrial Autocapture feature in 53 of 59 patients in whom bipolar pacing and unipolar sensing was performed. The authors developed a calibration routine to identify automatically those patients in whom atrial Autocapture could be programmed On, based on the polarization integral at loss of capture, the estimated maximum polarization integral, and the AERI. Preliminary analysis indicated that the AERI is a practical resource for beat-by-beat atrial capture detection when used with low polarization leads.

Aged↗

PubMed2002

Split atrial electrograms recorded during dual chamber pacing.

Split atrial electrograms (AEGs), as a measure of intraatrial conduction delay, have been previously identified during electrophysiological studies and as such, may be related to the development of atrial tachyarrhythmias. This article reports the finding of split AEGs observed in two patients with implanted dual chamber pacemakers. The event marker and the surface electrogram identified these AEGs by using and interpreting the intracardiac AEG derived from the atrial pacing lead.

Aged↗