Heart rate variability in Doberman Pinschers with and without echocardiographic evidence of dilated cardiomyopathy

Sympathetic Arousal Detection in Horses Using Electrodermal Activity

The continuous monitoring of stress, pain, and discomfort is key to providing a good quality of life for horses. The available tools based on observation are subjective and do not allow continuous monitoring. Given the link between emotions and sympathetic autonomic arousal, heart rate and heart rate variability are widely used for the non-invasive assessment of stress and pain in humans and horses. However, recent advances in pain and stress monitoring are increasingly using electrodermal activity (EDA), as it is a more sensitive and specific measure of sympathetic arousal than heart rate variability. In this study, for the first time, we have collected EDA signals from horses and tested the feasibility of the technique for the assessment of sympathetic arousal. Fifteen horses (six geldings, nine mares, aged 13.11 ± 5.4 years) underwent a long-lasting stimulus (Feeding test) and a short-lasting stimulus (umbrella Startle test) to elicit sympathetic arousal. The protocol was approved by the University of Connecticut. We found that EDA was sensitive to both stimuli. Our results show that EDA can capture sympathetic activation in horses and is a promising tool for non-invasive continuous monitoring of stress, pain, and discomfort in horses.

Heart rate variability analysis in horses for the diagnosis of arrhythmias

Heart rate variability (HRV) analysis has been performed on ECG-derived data sets for more than 170 years but is currently undergoing a rapid evolution, thanks to the expansion of the human and veterinary medical technology sector. Traditional HRV analysis was initially performed to identify changes in vago-sympathetic balance, while the most recent focus has expanded to include the use of complex computer algorithms, neural networks and machine learning technology to identify cardiac arrhythmias, particularly atrial fibrillation (AF). Some of these techniques have recently been translated for use in the field of equine cardiology, with particular focus on improving the diagnosis of arrhythmias both at rest and during exercise. This review focuses on understanding the basic HRV variables and important factors to consider when collecting data for use in HRV analysis. In addition, the use of HRV analysis for the diagnosis of arrhythmias is discussed from human, small animal and equine perspectives. Finally, the future of HRV analysis is briefly introduced, including an overview of future developments in this rapidly expanding and exciting field.

European Society of Veterinary Cardiology screening guidelines for dilated cardiomyopathy in Doberman Pinschers

BACKGROUND

Dilated cardiomyopathy (DCM) is the most common cardiac disease in large breed dogs and is inherited in Doberman Pinschers with a high prevalence (58%).

OBJECTIVE

The European Society for Veterinary Cardiology convened a task force to formulate screening guidelines for DCM in Dobermans.

RECOMMENDATIONS

Screening for occult DCM in Dobermans should start at three years of age and use both Holter monitoring and echocardiography. Yearly screening over the life of the dog is recommended, as a one-time screening is not sufficient to rule out future development of DCM. The preferred echocardiographic method is the measurement of the left ventricular volume by Simpson's method of discs (SMOD). Less than 50 single ventricular premature complexes (VPCs) in 24 h are considered to be normal in Dobermans, although detection of any number of VPCs is cause for concern. Greater than 300 VPCs in 24 h or two subsequent recordings within a year showing between 50 and 300 VPCs in 24 h is considered diagnostic of occult DCM in Dobermans regardless of the concurrent echocardiographic findings. The guidelines also provide recommendations concerning ancillary tests, that are not included in the standard screening protocol, but which may have some utility when recommended tests are not available or financially untenable on an annual basis. These tests include assay of cardiac biomarkers (Troponin I and N-Terminal pro-B-type Natriuretic Peptide) as well as a 5-min resting electrocardiogram (ECG).

CONCLUSION

The current guidelines should help to establish an early diagnosis of DCM in Dobermans.

Heart rate turbulence after ventricular premature beats in healthy Doberman pinschers and those with dilated cardiomyopathy

OBJECTIVES

To describe the measurement of heart rate turbulence (HRT) after ventricular premature beats and compare HRT in healthy Doberman pinschers and those with dilated cardiomyopathy (DCM), with and without congestive heart failure (CHF).

ANIMALS

Sixty-five client-owned Dobermans: 20 healthy (NORMAL), 31 with preclinical DCM and 14 with DCM and CHF (DCM + CHF).

METHODS

A retrospective study of data retrieved from clinical records and ambulatory ECG (Holter) archives, including data collected previously for a large-scale prospective study of Dobermans with preclinical DCM. Holter data were reanalysed quantitatively, including conventional time-domain heart rate variability and the HRT parameters turbulence onset and turbulence slope.

RESULTS

Heart rate turbulence could be measured in 58/65 dogs. Six Holter recordings had inadequate ventricular premature contractions (VPCs) and one exhibited VPCs too similar to sinus morphology. Heart rate turbulence parameter, turbulence onset, was significantly reduced in DCM dogs, whereas conventional heart rate variability measures were not. Heart rate variability and HRT markers were reduced in DCM + CHF dogs as expected.

CONCLUSIONS

Heart rate turbulence can be measured from the majority of good quality standard canine 24-hour Holter recordings with >5 VPCs. Turbulence onset is significantly reduced in Dobermans with preclinical DCM which indicates vagal withdrawal early in the course of disease. Heart rate turbulence is a powerful prognostic indicator in human cardiac disease which can be measured from standard 24-hour ambulatory ECG (Holter) recordings using appropriate computer software. Further studies are warranted to assess whether HRT may be of prognostic value in dogs with preclinical DCM and in other canine cardiac disease.

Heart rate variability parameters of myxomatous mitral valve disease in dogs with and without heart failure obtained using 24-hour Holter electrocardiography

Time-domain heart rate variability (HRV) parameters and the correlation between echocardiography and Holter examinations in dogs with myxomatous mitral valve disease (MMVD) were determined. Holter examination was also performed at different time frames: an entire 24-hour period, a four-hour period during sleep, and a four-hour period while awake. Ten healthy (control group) and 28 MMVD dogs, 15 with and 13 without heart failure, were evaluated. The SDANN (sd of the mean normal RR intervals for all five-minute segments during 24-hour Holter) and pNN(50) (percentage of differences between adjacent normal RR intervals that are >50 ms computed over 24-hour Holter) variables were significantly lower in the dogs with MMVD heart failure. The differences in HRV between the groups were only detected during the 24-hour evaluation period (P<0.05). There were high correlations (canonical analysis) between Holter and echocardiography examinations when considering pNN(50), SDANN, and LA/AO (left atrial to aortic root ratio) (r=0.92; P<0.05), indicating that both are important in evaluating MMVD dogs. SDANN and pNN(50) are measures of parasympathetic control of the heart, and thus, it is possible to infer that the MMVD dogs exhibit parasympathetic withdrawal during the development of heart failure.

Evaluation of N-terminal pro-B-type natriuretic peptide as a diagnostic marker of various stages of cardiomyopathy in Doberman Pinschers

OBJECTIVE

To evaluate the diagnostic value of plasma N-terminal pro-B-type natriuretic peptide (NT-proBNP) concentrations in Doberman Pinschers in various stages of dilated cardiomyopathy (DCM).

ANIMALS

328 Doberman Pinschers.

PROCEDURES

Staging of DCM was determined via analysis of results of physical examinations, 24-hour ambulatory ECG (Holter) recordings, and echocardiographic evaluations. Plasma samples for NT-proBNP assays were obtained at each examination. Concentrations of NT-proBNP were measured in 337 samples obtained from 196 healthy Doberman Pinschers (control dogs) and in 195 samples obtained from 132 Doberman Pinschers in various stages of DCM. These included dogs that had ventricular premature contractions (VPCs; 79 samples), echocardiographic changes (23 samples), or both (51 samples); 16 samples were from dogs with overt DCM, and 26 were from dogs that were considered normal during initial examination but developed DCM within 1.5 years after this assessment. Receiver operating characteristic curves were analyzed to determine sensitivity and specificity of NT-proBNP concentrations for detection of DCM.

RESULTS

NT-proBNP concentrations in dogs that had or developed DCM were significantly higher than those of control dogs. Sensitivity and specificity of NT-proBNP concentrations (cutoff value, > 400 pmol/L) to detect all stages of DCM were 81.1 % and 75.0%, respectively; sensitivity was 90.0% and specificity was 75.0% to predict echocardiographic changes. Specificity to detect echocardiographic changes was 90.4% at a cutoff value of 550 pmol/L.

CONCLUSIONS AND CLINICAL RELEVANCE

Plasma concentrations of NT-proBNP were increased in dogs with DCM and in apparently healthy dogs that developed DCM within 1.5 years after samples were obtained, compared with concentrations in control dogs.

Ability of a 5-minute electrocardiography (ECG) for predicting arrhythmias in Doberman Pinschers with cardiomyopathy in comparison with a 24-hour ambulatory ECG

BACKGROUND

Ventricular premature contractions (VPCs) are common in the occult stage of cardiomyopathy in Doberman Pinschers. Although the gold standard for detecting arrhythmia is the 24-hour ambulatory electrocardiography (ECG) (Holter), this method is more expensive, time-consuming and often not as readily available as common ECG.

OBJECTIVES

Comparison of 5-minute ECGs with Holter examinations.

ANIMALS

Eight hundred and seventy-five 5-minute ECGs and Holter examinations of 431 Doberman Pinschers.

METHODS

Each examination included a 5-minute ECG and Holter examination. A cut-off value of > 100 VPCs/24 hours using Holter was considered diagnostic for the presence of cardiomyopathy. Statistical evaluation included calculation of sensitivity, specificity, positive predictive value, and negative predictive value.

RESULTS

Holter examinations revealed > 100 VPCs/24 hours in 204/875 examinations. At least 1 VPC during a 5-minute ECG was detected in 131 (64.2%) of these 204 examinations. No VPCs were found in the 5-minute ECG in 73 (35.8%) examinations of affected Doberman Pinschers. A 5-minute ECG with at least 1 VPC as cut-off had a sensitivity of 64.2%, a specificity of 96.7%, a positive predictive value of 85.6% and a negative predictive value of 89.9% for the presence of > 100 VPCs/24 hours.

CONCLUSIONS AND CLINICAL IMPORTANCE

A 5-minute ECG is a rather insensitive method for detecting arrhythmias in Doberman Pinschers. However, the occurrence of at least 1 VPC in 5 minutes strongly warrants further examination of the dog, because specificity (96.7%) and positive predictive value (85.6%) are high and could suggest occult cardiomyopathy.

Cardiac troponin I in Doberman Pinschers with cardiomyopathy

BACKGROUND

Cardiac troponin I (cTnI) is useful for detection of cardiac myocyte damage, but its efficacy in detecting various stages of dilated cardiomyopathy (DCM) in Doberman Pinschers is unclear.

OBJECTIVES

To evaluate the diagnostic value of cTnI in various stages of DCM in Dobermans.

ANIMALS

Six hundred and fifty-three cTnI measurements of 336 Doberman Pinschers.

METHODS

Using a longitudinal study design, staging of the disease was based upon 24-hour-ambulatory-ECG (Holter) and echocardiography. A total of 447 cTnI measurements were performed in 264 healthy Dobermans, and 206 cTnI measurements in 75 Dobermans with cardiomyopathy. Eighty-eight cTnI samples were from dogs with >100 ventricular premature contractions (VPCs)/24 hour, but without echocardiographic changes ("VPC group"). Additional 19 samples originated from dogs with only echocardiographic changes ("ECHO group"), and 56 samples from dogs with both VPCs and echocardiographic changes ("VPC plus ECHO group"). Twenty samples were from dogs with clinical signs ("clinical group"). The group "incipient" included 23 dogs, that were considered to be normal according to Holter and echocardiography at the time of the exam, but that developed DCM within 1.5 years.

RESULTS

cTnI values of dogs in all disease groups, including the "incipient" (0.30+/-0.20) and "VPC group" (0.36+/-0.34), were significantly (P=.04, P<.001) higher than the control group (0.07+/-0.16). A cut-off value of >0.22 ng/mL had a sensitivity of 79.5% and a specificity of 84.4% to detect all forms of cardiomyopathy.

CONCLUSIONS AND CLINICAL IMPORTANCE

cTnI measurement is a valuable diagnostic test that can detect cardiomyopathy in dogs that are otherwise clinically normal.

Influence of antiarrhythmia therapy on survival times of 19 clinically healthy Doberman pinschers with dilated cardiomyopathy that experienced syncope, ventricular tachycardia, and sudden death (1985-1998)

Overtly healthy Doberman pinschers, having moderate to severe myocardial failure secondary to dilated cardiomyopathy, which experienced ventricular tachycardia, syncope or collapse, and sudden death were studied to determine the effect of antiarrhythmic medication on their clinical outcome. Antiarrhythmia drug therapy may have retarded sudden death in 13 treated dogs compared to the six dogs not administered antiarrhythmia drugs.

Differences between breeds of dog in a measure of heart rate variability

The vasovagal tonus index (VVTI), a time-domain indicator of heart rate variability, was measured in 92 dogs of six breeds (German shepherd dogs, labrador retrievers, cocker spaniels, boxers, bulldogs and cavalier King Charles spaniels). There was a significant difference in VVTI between the six breeds (P = 0.003). Brachycephalic dogs had a higher VVTI than other types of dog (P < 0.005), and when comparing individual breeds brachycephalic breeds tended to have a higher VVTI than non-brachycephalic breeds, although the difference was not always significant. The VVTI was negatively correlated with heart rate (P < 0.01) and dogs suffering from congestive heart failure had a lower VVTI than other dogs, whether compared within or between breeds (P < 0.01).

Assessment of heart rate variability in Boxers with arrhythmogenic right ventricular cardiomyopathy

OBJECTIVE

To assess heart rate variability (HRV) in Boxers with arrhythmogenic right ventricular cardiomyopathy (ARVC), assess the ability of HRV analysis to identify differences in Boxers on the basis of severity of their arrhythmia, and evaluate the use of HRV to determine whether persistently high sympathetic tone is present in these dogs.

DESIGN

Prospective study.

ANIMALS

24 Boxers with ARVC and 10 clinically normal non-Boxer dogs.

PROCEDURE

Boxers were categorized as dogs with congestive heart failure (CHF), dogs with < or = 2 ventricular premature complexes (VPCs)/24 h (designated unaffected), or dogs with > 1,000 VPCs/24 h (designated affected). Ambulatory electrocardiography (24 hours) was performed in each dog. Recordings were analyzed for HRV variables at a commercial laboratory; differences in HRV variables among groups were compared with 1-way ANOVA.

RESULTS

Compared with control non-Boxer dogs and Boxers without CHF (affected and unaffected Boxers), HRV was reduced in Boxers with CHF. No differences in HRV variables were detected between affected and unaffected Boxers. Inconsistent differences were identified between the control dogs and Boxers without CHF that had various degrees of arrhythmias.

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggest that persistently high sympathetic tone is not a consistent feature of ARVC. Differences in some HRV variables between Boxers without CHF and control dogs suggest that Boxers may have different autonomic control of heart rate, compared with that of clinically normal non-Boxer dogs. The usefulness of HRV analysis appears limited to Boxers with ARVC that have systolic dysfunction and CHF.

Evaluation of stability over time for measures of heart-rate variability in overtly healthy Doberman Pinschers

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, 73 +/- 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, very-low 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.

CONCLUSIONS 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.

Effect of severity of myocardial failure on heart rate variability in Doberman pinschers with and without echocardiographic evidence of dilated cardiomyopathy

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.