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- Author or Editor: Clay Calvert x
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Abstract
Objective—To determine whether results of analysis of heart-rate variability (HRV) in overtly healthy Doberman Pinschers remain stable over time.
Animals—24 overtly healthy client-owned Doberman Pinschers.
Procedure—The HRV was analyzed in time- and frequency- domains from 24-hour ambulatory electrocardiographic (Holter) monitor recordings. Activity during paired tests (tests 1 and 2) was similar (17 dogs) or nearly identical (7). Holter recordings and HRV analyses of those 17 dogs were repeated at a mean ± SD of 65 ± 50 weeks (median, 51 weeks; range, 10 to 177 weeks), whereas it was repeated for the other 7 dogs at 3 to 9 weeks (mean, 7.3 ± 2.1 weeks).
Results—Differences between test 1 and test 2 were not significantly different, except for 24-hour means of the normal beat-to-normal beat (NN) intervals in all 5-minute segments. Strongest correlations were for SD of all NN intervals and root mean square successive difference between adjacent NN intervals of the time-domain analyses and total power, verylow frequency power, and high-frequency power of the frequency-domain analyses. When activity during tests 1 and 2 in 7 dogs was stringently controlled, the differences were not significantly different, and correlation factors for the 24-hour HRV analyses exceeded 0.83.
Conclusion and Clinical Relevance—Variables from sequential HRV analyses in overtly healthy Doberman Pinschers with normal echocardiograms are moderately stable when physical activity is not stringently controlled and extremely stable for at least 3 to 9 weeks when physical activity is stringently controlled. (Am J Vet Res 2002;63:53–59)
Abstract
Objective—To determine results of ambulatory electrocardiography in and outcome of overtly healthy Doberman Pinschers with equivocal echocardiographic evidence of dilated cardiomyopathy.
Design—Case series.
Animals—44 overtly healthy (25 male, 19 female) Doberman Pinschers.
Procedure—24-hour ambulatory electrocardiographic (Holter) recordings with > 90% scan quality obtained the same day that echocardiography was performed were reviewed.
Results—Holter recordings from 42 of 44 (95%) dogs contained ventricular premature complexes (VPC). Fifteen of 44 (34%) dogs had > 100 VPC, 9 (20%) had > 500 VPC, and 5 (11%) had > 1,000 VPC. Nonsustained (< 30 seconds) ventricular tachycardia was detected in 4 dogs. Eighteen of 27 (67%) dogs with > 100 VPC, any couplets or triplets of VPC, or ventricular tachycardia developed dilated cardiomyopathy within 1 year, compared with 8 of 17 (47%) dogs with < 100 VPC, no couplets or triplets of VPC, and no ventricular tachycardia. Of the 18 dogs that did not develop dilated cardiomyopathy within 1 year, 11 (61%) did so within 3 years.
Conclusions and Clinical Relevance—Results suggest that a high percentage of Doberman Pinschers with equivocal echocardiographic evidence of dilated cardiomyopathy will be found to have VPC during 24-hour ambulatory electrocardiography and that most will develop echocardiographic abnormalities indicative of cardiomyopathy. (J Am Vet Med Assoc 2001;219:782–784)
Abstract
Objective—To determine whether heart rate variability (HRV) is reduced in Doberman Pinschers with dilated cardiomyopathy.
Design—Case series.
Animals—62 overtly healthy Doberman Pinschers.
Procedure—Heart rate variability was analyzed in time and frequency domains from data obtained during 24-hour ambulatory electrocardiographic Holter recordings in 41 overtly healthy Doberman Pinschers with normal echocardiograms and 21 overtly healthy Doberman Pinschers with abnormal echocardiograms.
Results—Heart rate variability usually was greater during night versus day, and 2 dogs with the most severe myocardial failure had reduced HRV.
Conclusions and Clinical Relevance—Reduced HRV was detected only in Doberman Pinschers with the most severe myocardial failure. Thus, HRV in less severely affected dogs is not reduced, or the normal sinus arrhythmia of dogs renders HRV relatively insensitive. Analysis of HRV did not provide additional information relative to the severity of left ventricular dysfunction or risk of sudden death from that which could be derived from echocardiography, analysis of Holter recordings, and signal-averaged electrocardiography. (J Am Vet Med Assoc 2001;219:1076–1080)
Abstract
Objective—To determine correlations between timedomain and frequency-domain variables of heart rate variability (HRV) derived from 24-hour recordings obtained by use of an ambulatory electrocardiographic recorder (Holter monitor).
Animals—59 overtly healthy Doberman Pinschers (41 without echocardiographic evidence of cardiomyopathy and 18 with precongestive heart failure attributable to cardiomyopathy).
Procedure—The HRV was analyzed from 24-hour recordings. Variables were calculated from the entire 24-hour recording as well as 4 user-selected time epochs. Comparisons were made for total power to SD of normal beat-to-normal-beat (NN) intervals (SDNN), ultra-low frequency power to SD of the means of NN intervals, low-frequency power and verylow- frequency power to mean of the SD of NN intervals, and high-frequency (HF) power to the root mean square successive difference of NN intervals (RMSSD) and percentage of NN intervals that varied from the previous NN interval by > 50 milliseconds (PNN50).
Results—58 of 66 (88%) comparisons revealed significant values, indicating that relationships between variables were not random (r > 0.7 in 41 of 66 [62%]) comparisons). Strong correlations (r > 0.8) were found between the square root of total power and SDNN and between HF power and RMSSD.
Conclusions and Clinical Relevance—Time-domain surrogates for variables of frequency-domain analysis variables that correlated in the dogs reported here are the same ones that reportedly correlate in humans. When 24-hour recordings obtained by use of a Holter monitor are used to calculate HRV, SDNN and total power as well as RMSSD and HF power are interchangeable. (Am J Vet Res 2001;62:1787–1792)
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)
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)
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)
