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Abstract

Objective—To characterize the salient variables of the time-domain analysis of heart rate variability (HRV) in clinically normal Doberman Pinschers and to compare those variables with those of Doberman Pinschers with cardiomyopathy and mild to moderate myocardial failure.

Animals—46 Doberman Pinschers.

Procedure—HRV was analyzed in the time-domain from 24-hour Holter recordings obtained from 28 Doberman Pinschers with normal echocardiograms and 18 Doberman Pinschers with echocardiograms consistent with mild to moderate myocardial failure.

Results—Significant differences in HRV variables between the 2 groups of dogs were not detected. The HRV was greater during the nighttime (12 AM to 6 AM), compared with the 24-hour day and an 18-hour (6 AM to 12 AM) period.

Conclusions and Clinical Relevance—HRV of dogs with mild to moderate myocardial failure was not different from that of clinically normal dogs, because there were no disturbances of autonomic balance, baroreceptor function, and other factors that influence HRV in the dogs with cardiomyopathy, or the sensitivity of time-domain analysis was overwhelmed by normal sinus arrhythmia. The techniques now used to study HRV have important limitations, especially in dogs, and better noninvasive tests of autonomic function are needed. ( Am J Vet Res 2000;61: 506–511)

Full access
in American Journal of Veterinary Research

Abstract

Objective

To determine whether ventricular late potentials (LP) identified by time-domain analysis (TDA) of the signal-averaged ECG could be identified by three-dimensional frequency-domain analysis (FDA).

Animals

11 dogs (9 of which subsequently died suddenly) with ventricular tachyarrhythmias (10 with ventricular tachycardia) and abnormal TDA of the signal-averaged ECG.

Procedure

Signal-averaged ECG that were abnormal when analyzed in the time domain subsequently were processed further in the frequency domain. Correlation ratios were calculated, and spectro-temporal maps were plotted, which were then compared with control data.

Results

Three-dimensional FDA did not detect LP.

Conclusions and Clinical Relevance

LP may be detectable by TDA of the signal-averaged ECG and may be a specific marker for VT and sudden death in some dogs. However, FDA by use of the method applied in this study is invalid. (Am J Vet Res 1999;60: 396-401)

Free access
in American Journal of Veterinary Research

Objective

To determine whether ventricular late potentials, detected by means of signal-averaged electrocardiography (SAECG), were associated with sudden death in Doberman Pinschers with occult cardiomyopathy.

Design

Case series.

Animals

39 Doberman Pinschers with occult cardiomyopathy.

Procedure

Cardiomyopathy was diagnosed by means of serial echocardiography and ambulatory electrocardiography; SAECG was performed 1 or more times for each dog.

Results

12 dogs died suddenly; the other 27 died after developing overt clinical signs of congestive heart failure. Results of SAECG were associated with outcome, and dogs in which ventricular late potentials were detected were more likely to die suddenly. However, 5 dogs for which results of SAECG were normal (n = 2) or equivocal (3) also died suddenly.

Clinical Implications

Results suggest that SAECG may be useful in predicting whether Doberman Pinschers with occult cardiomyopathy, confirmed on the basis of results of echocardiography, are at risk of dying suddenly. However, the possibility of sudden death cannot be ruled out simply because results of SAECG are normal. (J Am Vet Med Assoc 1998;213:235-239)

Free access
in Journal of the American Veterinary Medical Association
in Journal of the American Veterinary Medical Association

Abstract

Objectives

To establish data for selected variables of the signal-averaged ECG and determine whether sedation affects segment lengths and points within the terminal QRS complex where windows began.

Sample Population

Overtly healthy dogs with no detected abnormalities.

Procedure

Signal-averaged ECG (600 beats) were obtained from dogs in left-lateral recumbency, using X, Y, and Z leads with 26-gauge subdermal platinum electrodes. Frequency-domain analyses were performed by fast Fourier transform (FFT), using a postprocessing computer software package. Analyses were extracted from 30-, 40-, and 50-millisecond windowed (Blackman-Harris) segments of the terminal 10 or 20 milliseconds of the QRS complex and ST segment. Correlation ratios were calculated by cross-correlation of frequency spectra of each FFT in the range of 40 to 200 Hz. The reference spectrum was the last FFT (nearest the T wave). Spectro-temporal maps were plotted for each analysis.

Results

Noise levels were < 1 μV. Sedation resulted in less noise and slower heart rate, but did not affect results. Correlation ratios were not different among 30-, 40-, and 50-millisecond segments, but were lower when 20 (vs 10) milliseconds of the terminal QRS was included. Spectro-temporal maps were similar in all subjects.

Conclusions

Use of sedation facilitated the procedure without affecting results. Segment lengths of 40 and 50 milliseconds, beginning 10 milliseconds prior to the end of the QRS complex and analyzed in the range of 40 to 200 Hz, yielded correlation ratios > 67%, 95% of the time.

Clinical Relevance

Spectro-temporal mapping may identify dogs with ventricular late potentials (high-frequency signals commonly associated with myocardial fibrosis) that may be at increased risk of sudden death. (Am J Vet Res 1997;58:211–217)

Free access
in American Journal of Veterinary Research

Abstract

Objective—To characterize ambulatory electrocardiographic results of overtly healthy Doberman Pinschers and determine associations between those results and development of dilated cardiomyopathy.

Design—Cohort study.

Animals—114 (58 male, 56 female) overtly healthy Doberman Pinschers without echocardiographic evidence of cardiac disease on initial examination.

Procedure—Echocardiograms and 24-hour ambulatory electrocardiograms (Holter recordings) were obtained initially and at variable intervals. The status (live vs dead) of all dogs was known at least 2 years and as long as 10 years after initial examination (mean [± SD] follow-up time, 4.33 ± 1.84 years). Associations between development of dilated cardiomyopathy and number of ventricular premature contractions (VPC), age, and sex were determined.

Results—55 dogs (48%) did not have VPC on initial Holter recordings, and only 8 dogs had > 50 VPC/24 hours. The likelihood that a dog would have VPC was associated with increasing age and being male. At least 1 VPC/24 hours, and in particular, > 50 VPC/24 hours or ≥ 1 couplet or triplet of VPC/24 hours, were predictive of subsequent development of dilated cardiomyopathy. Fifty-four dogs (47%) developed dilated cardiomyopathy; 12 were still alive at the end of the study, and 42 had died. Twenty-five of these 42 dogs died after the onset of congestive heart failure (CHF), 15 died suddenly before the onset of overt CHF, and 2 died of noncardiac causes. More males developed dilated cardiomyopathy than females, and dogs that died suddenly were approximately 1 year younger than those that developed CHF.

Conclusions and Clinical Relevance—Results of high-quality Holter recordings may be used to identify overtly healthy Doberman Pinschers that are at a high risk for dilated cardiomyopathy. ( J Am Vet Med Assoc 2000;216:34–39)

Full access
in Journal of the American Veterinary Medical Association