Disorders of the Cardiovascular System

Assessment of systolic and diastolic function in clinically healthy horses using ambulatory acoustic cardiography

“…The fourth heart sound is heard in late diastole immediately prior to S1. It should be detected in nearly all horses in sinus rhythm and is particularly pronounced in horses with slow heart rate and long PQ interval [5,49,50]. In agreement with this study, the literature suggests that auscultatory characteristics of S4 appeared similar in animals of different age [49].…”

“…Ambulatory Holter ECG recordings have previously been used in horses for heart rate and rhythm analyses over prolonged periods of time [5].…”

“…Cardiovascular disease accounts for 5.1% of deaths in 15-23 years old horses and for 8.5% of deaths in horses older than 24 years [2]. The most common cardiac diseases include mitral and aortic insufficiency [2][3][4][5], ventricular septal defects [5,6] and arrhythmias such as atrial fibrillation [5,7,8]. Because progression of disease into heart failure is relatively rare and heart failure is only diagnosed when overt clinical signs of exercise intolerance and congestion develop, its real prevalence is largely unknown [5].…”

“…In field practice, these primarily include physical examination, careful cardiac auscultation, exercise testing and laboratory examination. Specialised clinicians and larger referral centres also offer resting electrocardiography (ECG), stress ECG, ambulatory Holter ECG and event monitoring, transthoracic echocardiography, noninvasive blood pressure measurement and cardiac catheterisation [5]. These more advanced methods require extensive training and experience and access to the necessary equipment.…”

“…In a recent study, it was shown that systolic time intervals can be altered in horses with mitral and aortic insufficiency, but their clinical value could not be well documented and remains uncertain at this time [28]. Similarly, S3 can be heard in healthy horses and in horses with heart disease, but lacking accurate methods for quantification of the strength of S3, its diagnostic and prognostic value in horses with heart disease is not well established [5,29].…”