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The aim of this study was to demonstrate the diagnostic accuracy of P-wave dispersion in predicting recurrence of atrial fibrillation in dogs with sinus rhythm restoration after external cardioversion. The study was performed on 15 dogs, which underwent electrical external cardioversion after atrial fibrillation. Nine-lead surface electrocardiogram of each dog was recorded 1 min after the cardioversion process to measure the P-wave duration. Dogs with recurrent atrial fibrillation had significantly higher P-wave dispersion compared to dogs that had a sinus rhythm lasting more than 3 months (9.26 ±2.01 ms vs 20.9 ±2.18 ms, P=0.001). This study suggests that P-wave dispersion analysis in dogs after a successful external electrical cardioversion has diagnostic accuracy to predict the recurrence of atrial fibrillation.
Heart rate turbulence (HRT) is modulated by the baroreceptor reflex and it was suggested that it could be used as a measure of autonomic dysfunction. Impaired HRT is of a significant prognostic value in humans after myocardial infarction, suffering from dilated cardiomyopathy and patients with heart failure. So far no studies were performed assessing the importance of HRT in dogs. The aim of this study was to prospectively evaluate the HRT turbulence onset (TO) and the turbulence slope (TS) in healthy dogs and in dogs with DCM and to compare the HRT in dogs with DCM that died during the first 30 days of observation and dogs with DCM that survived the first 30 days after the HRT analysis. The current study was aimed at determining reference value of the TO and TS of HRT in healthy dogs (control group) and dogs with dilated cardiomyopathy (DCM group). The tests were carried out on 30 healthy dogs and 30 dogs with DCM composed of Boxers, Doberman pinschers and Great Danes, of different sexes and body weights from 22 to 72 kg, aged between 1.5 and 11.5 years, submitted to the 24-hour Holter monitoring. HRT parameters were calculated using an HolCard software algorithm. TO is a percentage difference between the heart rate immediately following ventricular premature complex (VPC) and the heart rate immediately preceding VPC. TS corresponds to the steepest slope of the linear regression line for each sequence of five consecutive normal intervals in the local tachogram. The average TO in healthy dogs was determined as -13.55 ± 11.12%, TS was 21.33 ± 9.66 ms/RR. TO in dogs with DCM was determined as - 2.61 ± 2.1% and TS was 6.15 ± 3.86 ms/RR. Parameters of HRT were statistically significantly decreased (p<0.01) in dogs with DCM. HRT TO and TS were statistically significantly decreased in dogs with DCM. Dogs with DCM that survived more than 30 days of observation had HRT statistically significantly decreased in comparison to dogs with DCM that died after the 30’th day of observation. Decreased HRT parameters in dogs with DCM suggest an autonomic neuropathy which principally consists of the withdrawal of the cardiac parasympathetic tone. The more the autonomic neuropathy is advanced the faster the death of the dog with DCM might occur, with no correlation with the level of the heart failure.
The purpose of this study was to develop prognostic models for heart failure in dogs with dilated cardiomyopathy (DCM). The prospective study included 26 dogs with DCM and 58 healthy dogs. The ervation time median was 250 days (1-600 days). All the dogs were clinically examined, had echocardiography, electrocardiography, and morphological and biochemical blood sampling. Twenty four deaths were found in the group of dogs with DCM and 1 demise in the healthy dog's group. There was a significant increase in the level of NT-pro-BNP and cTnI (p<0.0005) in the group of dogs with DCM and a significant higher level of NT-pro-BNP and cTnI (p<0.0005) in the dead dogs from group with DCM that died or were euthanized up to the 60'th day of observation, compared to the animals that outlasted over 60 days of observation. The median level of NT-pro-BNP in the dogs which had short survival period (no more than 60 days) was 4865 pmol/L and the median level of cTnI in the same group of dogs was 0.63 ng/ml. The median level of NT-pro-BNP in the group of dogs with DCM, which lived longer than 60 days of observation was 978 pmol/l and the median level of cTnI in this group was 0.1 ng/ml. The level of NT-pro-BNP (r=0.79) and cTnI (r=0.4) correlated with the dogs' death. NT-pro-BNP and cTnI measurements could be useful to evaluate the survival the dogs with DCM. Increased level of NT-pro-BNP and cTnI is a bad prognosis. In the performed analysis of the Cox hazard regression it was found that cTnI level has a significant impact of the survival of the dogs (HR=8.54; Cl 1.1-46.6; p=0.02).
Heart rate turbulence (HRT) is a new electrocardiographic parameter used in human medicine to predict the possibility of death in patients with cardiac diseases. There is no information about HRT in healthy dogs and those with cardiac diseases. The aim of the present study was to compare the HRT in healthy Boxers dogs with Boxers with mild and moderate subaortic stenosis (SAS), to disclose the relationship between HRT and specific echocardiographic parameters and to evaluate if HRT can be used as a prognostic value in dogs with aortic stenosis. The study revealed significantly lower values of turbulence onset (TO) and turbulence slope (TS) HRT dogs with SAS (TO = -0.76 ± 2.6, TS = 7.1 ± 3.21) in compared with healthy dogs (TO = -7.45 ± 9.72, TS = 14.33 ± 8.76). TO values correlated with the left ventricular mass (LVM)/body mass factor (r = 0,32; p = 0.048). Based on the results obtained it can be stated that dogs with SAS have a compromised baroreceptor response, which can influence the mortality of the animals with described cardiac defect.
The aim of this research was to evaluate the assessment of changes of heart electrophisiological parameters, the determination of the frequency of occurrence and kinds of arrhythmias possible to release in invasive electrophysiological study of the heart and the assessment of the connection between electrophysiological parameters and morphological changes of the heart muscle. The experimental material included 10 pigs of Wielka Bia³a Zwis³oucha breed. Hyperthyroxinemia was induced experimentally in 5 pigs through the oral administration of L-tyroxine at a dose of 20 µg/kg body weight once daily for 8 weeks. The control group included 5 pigs which were not administered L-tyroxine. The electrophysiological study of the heart was carried out 4 times, preceded by a blood test. The statistically significant shortening of the atrial effective refraction period and atrio-ventriculat nodal refraction period, concentric hypertrophy of the heart muscle, and change of biochemical blood parameters were observed.
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