Biomedical subjects

A R Gelzer

Publications and source records attributed to A R Gelzer.

5 recordsLinked to original sources

PubMed2000

Temporal organization of atrial activity and irregular ventricular rhythm during spontaneous atrial fibrillation: an in vivo study in the horse.

INTRODUCTION: Atrial fibrillation (AF) is common in healthy horses. We studied the temporal organization of AF to test the hypothesis that the arrhythmia is governed by a high degree of periodicity and therefore is not random in the horse. Further, we surmised that concealed conduction of AF impulses in the AV node results in an inverse relationship between AF frequency and ventricular frequency. METHODS AND RESULTS: Fast Fourier transform (FFT) analysis of atrial activity was done on signal-averaged ECGs (n = 11) and atrial electrograms (n = 3) of horses with AF at control (C), after quinidine sulfate (22 mg/kg by mouth every 2 hours) at 50% time to conversion (T50), and immediately before conversion (T90) to sinus rhythm. FFT always revealed a single dominant frequency peak. The mean dominant frequency decreased until conversion (C = 6.84 +/- 0.85 Hz, T50 = 4.87 +/- 1.5 Hz, T90 = 3.41 +/- 1.18 Hz; P < 0.001). Mean AA intervals (n = 500) gradually increased after quinidine. Mean RR intervals (n = 500), standard deviation of the mean (SDM), Poincaré plots, and serial autocorrelograms (SACs) of 500 RR intervals were measured at C and T90 to determine the ventricular response to AF and quinidine-induced changes in the variability of the ventricular response. Mean RR interval and SDM were reduced after quinidine (C = 1431 +/- 266 msec and 695 +/- 23 msec; T90 = 974 +/- 116 msec and 273 +/- 158 msec, respectively; P < 0.01). Poincaré plots and SAC at C and at T90 revealed a significant correlation of consecutive RR intervals typical of a system with a deterministic behavior. At T90, the variability of RR intervals was reduced and the overall periodicity of RR intervals was increased after quinidine administration. CONCLUSION: In the horse, AF is a complex arrhythmia characterized by a high degree of underlying periodicity. The inverse AA-to-RR interval relationship and reduced variability of RR intervals after quinidine suggest that the ventricular response during AF results from rate-dependent concealment of AF wavelets bombarding the AV node, which nevertheless results in a significant degree of short-term predictability of beat-to-beat changes in RR intervals.

Animals↗

PubMed1999

Introduction of an endocardial pacing lead through the costocervical vein in six dogs.

Lead dislodgement is one of the most common complications of endocardial pacing lead implantation in dogs. Incidence of lead displacement appears to be higher in large-breed, compared with small-breed, dogs, suggesting that excessive neck movements may be a contributing factor. To avoid introducing pacing leads through a vein in the neck, we developed a technique for implantation of endocardial pacing leads through the right costocervical vein. A right second intercostal space thoracotomy was performed to expose the vein, and the pacing generator was placed in the musculature over the lateral aspect of the thorax. The technique was performed in 6 dogs, 5 of which had had an endocardial pacing lead dislodge. None of the dogs had problems with lead dislodgement during follow-up periods of 15 to 20 months. Implantation of endocardial pacing leads through the costocervical vein should not be considered a replacement for implantation through the jugular vein. However, we believe that this technique is indicated for large dogs in which endocardial pacing leads implanted through the jugular vein have dislodged.

Animals↗

PubMed1997

Validation of a telemetry system for measurement of blood pressure, electrocardiogram and locomotor activity in beagle dogs.

A model is described for the continuous recording of arterial blood pressure, electrocardiogram and locomotor activity by telemetry in conscious unrestrained beagle dogs. Validation of the system was accomplished by simultaneous acute catheterisation and telemetry recording ten weeks after implantation, under anaesthesia. Systolic, mean and diastolic pressures, measured over 30-40 mm Hg, were not significantly different. Telemetric measurements in their home cage over several days revealed clear diurnal variations in blood pressure, heart rate, locomotor activity and contractility (QA-interval). Despite these diurnal variations the 24 h mean values were highly reproducible. This model was further characterised by pharmacological interventions designed to increase contractility (ouabain) and blood pressure (NG-nitro-L-arginine methyl ester) and to lower blood pressure (isosorbide-5 mononitrate and molsidomine). The high daily reproducibility of cardiovascular parameters allowed each dog to be used as its own control and allowed investigation of these long-acting active agents, which would not have been possible with conventional methods for cardiovascular measurement. These findings demonstrate the utility of this model for investigations into blood pressure regulation as well as the potential for pharmacological intervention.

Animals↗

PubMedDate not supplied

Accessory lung lobe torsion and chylothorax in an Afghan hound.

Torsion of the accessory lung lobe is extremely rare and has been reported only in one human. Accessory lung lobe torsion (LLT) and chylothorax occurred in a 3.5-year-old, male Afghan hound. An exploratory thoracotomy was used to remove the torsed lung lobe. When medical management of the chylous effusion failed, thoracic duct ligation was performed, resulting in resolution of the effusion. The dog remains clinically healthy 29 months postoperatively.

Animals↗

PubMedDate not supplied

Primary hyperaldosteronism in two cats.

A condition of primary hyperaldosteronism resulting from an adrenal tumor in two cats is presented and was characterized by hypertension, hypokalemia, inappropriate kaliuresis, low normal plasma renin activity, and markedly increased serum aldosterone concentration. One of the two cats underwent a laparotomy, and in this case hypertension and hypokalemia resolved following the removal of an adrenal tumor.

Adrenal Gland Neoplasms↗