Topic:Electrocardiography
Electrocardiography (ECG) in horses is a diagnostic tool used to assess the electrical activity of the heart. It involves recording the electrical impulses that govern heartbeats, providing insights into cardiac function and rhythm. This non-invasive method is useful for identifying arrhythmias, conduction disturbances, and other cardiac abnormalities in equine patients. Electrocardiography can be performed at rest or during exercise to evaluate cardiac performance under different physiological conditions. This page compiles peer-reviewed research studies and scholarly articles that explore the methodology, interpretation, and clinical applications of electrocardiography in equine health.
Equine heart disease. An overview. The clinician must appreciate unique aspects of equine cardiovascular physiology in order to distinguish normal variation from a pathophysiologic state. Cardiovascular problems in the horse include auscultation of cardiac murmurs, identification of cardiac arrhythmias, and recognition of congestive heart failure. A cardiac data base including history, general and cardiovascular examination, and resting and postexercise electrocardiogram are necessary to evaluate most horses for significant heart disease. Additional studies, such as echocardiography and cardiac catheterization, are useful in se...
Diagnosis and treatment of cardiac arrhythmias. Cardiac arrhythmias are probably more common in horses than in any other domestic animal species. The most frequent clinical complaint associated with cardiac arrhythmias is exercise intolerance. Physical examination is characterized by auscultation abnormalities such as fast or slow heart rate, irregular rhythm, extra sounds, long pauses, or abnormal heart sounds. The electrocardiogram is used to make a definitive diagnosis of the dysrhythmia. Other laboratory and cardiac function tests are employed to determine the etiology and to assess the significance of the arrhythmia. Antiarrhythmic the...
[Electrocardiography in the horse. (2). Disorders of impulse formation and impulse conduction]. The cardiac arrhythmias, classified in disturbances of impulse formation and conduction disturbances, their genesis and clinical significance are described and illustrated with electrocardiograms, registered with the bipolar chest leads.
[Electrocardiography in the horse (1). Principles and normal picture]. The physiological and technical basis of the electrocardiography are shortly explained. The electrodes used for the recording of bipolare thoracal leads, their fixation on the horse, the practical procedure of a ECG-recording, its appearance and variation are described and illustrated. A recommendation for a systematic evaluation and interpretation is being proposed.
Relationship between potassium administration, hyperkalaemia and the electrocardiogram: an experimental study. Hyperkalaemia affected the equine myocardium. The minimum plasma potassium concentration required to induce electrocardiographic changes was 6.2 mmol/litre and severe cardiotoxic effects were observed at levels of 8.0 to 10.1 mmol/litre in this experimental situation. The most consistent sign of hyperkalaemia was broadening and flattening of the P wave, which was generally associated with a change in T waves in the chest lead from negative to positive. The more pronounced the hyperkalaemia, the less pronounced the P wave and the more peaked positive the T wave. Severe hyperkalaemia was associa...
Echocardiography in foals from birth to three months old. Simultaneous echocardiograms, phonocardiograms and electrocardiograms were performed on 16 foals at the following times after birth: 15 mins, 60 mins, 2, 4, 12, 24, 48 h, four, seven, 14 days and four, eight and 12 weeks. Positive correlations were found between both age and body weight and the following measurements: left ventricular end-diastolic dimension, right ventricular end-diastolic dimension, left atrial dimension and aortic root dimension, posterior left ventricular wall thickness and interventricular septal thickness. Heart rate was negatively correlated with left ventricular electr...
Blood pressure, electrocardiogram and echocardiogram measurements in the growing pony foal. Twelve newborn pony foals underwent cardiovascular examinations (auscultation, arterial blood pressure measurements, electrocardiograms and M-mode echocardiograms) on their first day of life and then on Days 7, 14, 21, 30, 60 and 90. An age dependent, statistically significant, rapid increase of the arterial blood pressure in the first month was documented together with a slower decrease of the resting heart rate after two and three months of life. Innocent soft systolic murmurs were audible over the left heart base in a large number of the foals. The electrocardiograms showed age dependent in...
Interrelationship of some electrocardiogram amplitudes, time intervals and respiration in the horse. The relationship of the scalar and vector magnitudes of the QRS waveform to RR, PR and respiration was examined in 10 horses in regular rhythm using an orthogonal lead system. There were no significant changes in the durations of RR and PR with respiration. The amplitudes of the scalar variables XR and YR were directly related and that of XQ (or XS) and ZR were inversely related to PR in this group of horses. The peak spatial vector magnitude and its H-plane angle were directly related to PR and inversely related to RR. The effect of inspiration on the QRS was a decrease in YR and ZR, an incre...
Three cases of ruptured mitral valve chordae in the horse. The paper describes clinical observations in three horses with ruptured mitral valve chordae. Horses with ruptured mitral valve chordae may have a history of sudden onset of acute distress with predominantly respiratory symptoms. On auscultation there will be a widespread pansystolic murmur with an extension of the area of cardiac auscultation. The third heart sound may be very pronounced and unduly prolonged, associated with high volume flow during early ventricular filling in diastole. However, these sounds are not specific for chordal rupture--they are typical of severe mitral regurgitation...
Effects of clenbuterol hydrochloride on certain respiratory and cardiovascular parameters in horses performing treadmill exercise. Five standardbred geldings received intravenous clenbuterol hydrochloride and saline in a crossover experiment to evaluate the effects of clenbuterol on certain cardiorespiratory parameters during and after treadmill exercise. The exercise test consisted of four steps. Step 1 at a speed of 76 m per minute, step 2 at 129 m per minute, step 3 at 190 m per minute and step 4 at 236 m per minute. The duration of each step was two minutes, except step 4 which was four minutes. The treadmill was set at a grade of 19 per cent. Before exercise, 30 minutes after clenbuterol or saline administration, art...
Studies on the physiopathology of chronic obstructive pulmonary disease in the horse. VIII. Mean modal vectors of the P wave and the QRS complex. Mean modal vectors of P1, P2 and QRS were determined in the 3 planes of a semi-orthogonal EKG lead system in 17 horses and ponies with chronic obstructive pulmonary disease (COPD) and in 17 clinically normal horses and ponies. Subjects were paired so that the heart rates of each pair were not dissimilar by more than 2 cycles per minute. Probably significant differences were observed between the mean angles of P1 vectors in the transverse and sagittal planes (T plane, normal = 324 degrees +/- 24,6 degrees, COPD = 342 degrees +/- 21,0 degrees, t = 2,0, P less than 0,05; S plane, normal = 331 deg...
Electrocardiographic changes in induced hyperkalemia in ponies. In 11 crossbred ponies, hyperkalemia was induced by acute intracardiac infusion of a 0.4M solution of potassium chloride. The ECG changes noticed can be assigned to 4 stages: (1) a widening and a lowering of amplitude followed by inversion and final disappearance of the P wave; (2) an increase in the amplitude of the T wave; (3) an increase in the QRS interval, with some irregularity in the ventricular rate; and (4) periods of cardiac arrest that became terminal or were followed by ventricular fibrillation. At plasma potassium values of greater than 7.5 mM/L, the T-wave amplitude and duration ...
Multiple congenital heart anomalies in five Arabian foals. Five Arabian or half-Arabian foals with suspected multiple cardiac anomalies were examined. Various combinations of clinical examination, electrocardiography, angiocardiography, cardiac catheterization, blood gas analysis, radiography, and echocardiography resulted in clinical data that allowed accurate antemortem diagnoses to be made. In 4 cases, the clinical diagnosis was substantiated by postmortem findings. The confirmed diagnoses were: pseudotruncus arteriosus, a combination of patent ductus arteriosus, pulmonic stenosis, and tricuspid stenosis, pentalogy of Fallot, and tricuspid atresia....
Microprocessor-based system for collection and storage of the equine vectorcardiogram. To evaluate the clinical application of a semiorthogonal lead system for use in the horse, an inexpensive means of recording and storing the ECG was required which would allow the subsequent vectorcardiographic analysis to be computerized. In investigating the various options for the system the basic requirements for the digitization of analogue data were reviewed and previous studies examined. The system subsequently developed used an 8080 microprocessor and a multichannel 8-bit analogue to digital converter. This unit was signal-level compatible with the laboratory recorder used in the study...
The equine electrocardiogram with standardized body and limb positions. Eleven-lead electrocardiograms (ECGs) were recorded from 50 Thoroughbred (TB) and 50 Standard bred (SB) horses at rest with 40 tracings being selected from each group for more complete analysis. Incomplete atrioventricular block with dropped beats commonly reported in mature horses was recorded only in the TB (15%), while wandering of the atrial pacemaker (WAP) thought also to be associated with variations in tone of the autonomic nervous system was detected almost equally in both breeds (30%). In some horses (12.5%), the initial component of the P wave (P1) did not vary as seen with WAP but h...
[ECG similarities in the parents and offspring of thoroughbred horses]. The ECG characters were studied in two sires (Manrico and Infernal) and their 26-membered set of progeny as well as in one mare (Victoire) and her five daughters. The confer of some ECG characters from the sire's side as well as from the mare's side to the offspring was demonstrated. The consistency of some ECG characters was particularly obvious in externally dominant Manrico sire and his offspring as well as in the breeding mare and her five daughters (inclination of the electric cardiac axis, intrinsicoid deflexion lag, P wave shape, deep S in the 3rd connection).
Equine laryngeal hemiplegia part II: Some clinical observations. Some clinical features of laryngeal hemiplegia in 127 horses are described. Possible aetiologic factors were found in only 11% of affected animals. The onset of clinical signs was either sudden or insidious. The majority of cases were presented because of an abnormal respiratory noise made at exercise. Other clinical signs, particularly those usually attributed to laryngopalatal dislocation, were observed in a substantial proportion of affected animals. In all cases surveyed the left arytenoid was affected, although in 3 animals a bilateral laryngeal dysfunction was noted. Thirty of 65 animals...
Monitoring the anesthetized horse. The objectives of monitoring are to gain much information as possible about the anesthetized horse and to follow changes in that information, with the ultimate aim of making anesthesia and surgery as safe as possible for the horse. Information necessary to achieve that aim will vary depending on patient category. For example, a young, healthy horse undergoing a short elective procedure can be clinically well monitored by patient signs, electrocardiogram, and indirect blood pressure response. More invasive monitoring is justified and warranted if the health status of the horse is in question. T...
Effects of xylazine and ketamine hydrochloride on the electroencephalogram and the electrocardiogram in the horse. A continuous series of electroencephalograms (EEG) was obtained from each of 6 mature horses which had been given xylazine and ketamine hydrochloride IV. Electrocardiograms and respiratory rates were also obtained. The EEG of the unsedated standing adult horse displayed a dominant fast activity in the range of 25-35 Hz, 5-30 microV superimposed over slower 1-4 Hz, 10-50 microV activity with occasional 10-14 Hz, 10-40 microV spindle-type activity. The xylazine-sedated horse displayed hypersynchronous EEG patterns, with the dominant activity being 1-3 Hz, 10-70 microV with overlying mixed freque...