Topic:Heart Murmur
Heart murmurs in horses are audible vibrations or sounds produced by turbulent blood flow within the heart or large blood vessels. These sounds are detected during auscultation and can vary in intensity, timing, and duration. Heart murmurs may be associated with structural heart abnormalities, such as valvular insufficiencies or septal defects, or they might occur in the absence of any underlying pathology, often termed "innocent" murmurs. The evaluation of heart murmurs involves assessing their characteristics and potential impact on the horse's cardiovascular function. This page compiles peer-reviewed research studies and scholarly articles that explore the etiology, classification, and clinical implications of heart murmurs in equine patients.
Pulsed wave Doppler echocardiography in normal horses. Reference values were established for selected Doppler derived variables from a group of 40 normal Thoroughbred and Thoroughbred cross horses. Standard two-dimensional (2-D) images used for guiding the Doppler sampling site allowed accurate alignment with flow. Tricuspid inflow velocities during rapid filling (E) and atrial contraction (A) were significantly higher when recorded from a right parasternal angled view than from a right parasternal long-axis view. In 8 horses the tricuspid inflow peak A velocity was higher than the peak E velocity. The peak acceleration of blood flow was higher (P...
A survey of cardiac auscultatory findings in horses. Auscultation was used to examine 545 horses for cardiac murmurs and some arrhythmias. The most significant finding was the high prevalence of right-sided holosystolic or pansystolic plateau-type murmurs compatible with a diagnosis of tricuspid regurgitation in National Hunt racing Thoroughbreds of all ages (16.4%). This condition was found in 4.7% of flat-racing Thoroughbreds, 3.7% of non-racing Thoroughbreds and Thoroughbred crosses, and in none of the ponies examined. High prevalences of left-sided early systolic murmurs (53%), left-sided early diastolic murmurs (23%), right-sided early dias...
[B-mode, M-mode and Doppler sonographic findings in mitral valve insufficiency of horses]. B- and M-mode echocardiography was performed on 38 horses. 34 patients had systolic heart murmur with the point of maximal intensity over mitral valve. Additionally, 17 of these patients were examined with the pulsed wave doppler echocardiography (Vingmed 200). In 26 patients with cardiac murmur and in 4 patients without cardiac murmur a mitral valve insufficiency was diagnosed by echocardiography. In 8 horses with a systolic murmur over mitral valve M- and B-mode evaluation could not reveal a haemodynamic importance of the murmur. The diagnosis of MVI was based on a dilation of left atrium wi...
Medical evaluation of the cardiovascular system. The approach to pre-purchase evaluation of the equine cardiovascular system is discussed with emphasis on cardiac auscultation and on the terminology that should be used when reporting clinical findings. Innocent cardiac murmurs and arrhythmias are contrasted with those that should be considered as reliable signs of cardiovascular disease. Ultrasonography and electrocardiography are recommended to establish baseline values for future reference, to support opinions rendered by the examining veterinarians, or to provide for diagnosis and treatment.
Vegetative endocarditis in an Appaloosa gelding. A 5-year-old Appaloosa gelding was presented with a history of intermittent multiple joint swelling, weight loss, and anemia. Physical examination and clinical pathology revealed a grade IV/VI holodiastolic murmur, louder on the left, and a marked hyperproteinemia. Echocardiography of the heart demonstrated a large vegetative lesion on one of the aortic valve cusps. Blood cultures did not elucidate the causative organism, and the disease was refractory to empiric antibiotic therapy. The horse was euthanized after approximately 2 months of therapy.
Tetralogy of Fallot and segmental uterine aplasia in a three-year-old Morgan filly. A 3-year-old Morgan filly was presented to the University of Florida, Veterinary Medical Teaching Hospital, for heart murmur, poor growth, and progressive exercise intolerance. Thoracic radiographs, cardiac ultrasound, cardiac catheterization, and differential blood gases were utilized to tentatively diagnose tetralogy of Fallot. Postmortem examination confirmed tetralogy of Fallot and additionally revealed segmental uterine aplasia.
Confirmation by Doppler echocardiography of valvular regurgitation in a horse with a ruptured chorda tendinea of the mitral valve. Regurgitation of blood through the left atrioventricular valve owing to the rupture of one of the chordae tendineae of the valve was diagnosed in a horse with sudden-onset respiratory distress and a holosystolic cardiac murmur. Severe regurgitation was confirmed with Doppler echocardiography and prolapse of part of the valve leaflet was identified with B-mode ultrasonography. The rupture of one of the chordae tendineae of a right accessory cusp of the left atrioventricular valve was confirmed post mortem. Bronchiolitis, multifocal haemorrhages and haemorrhagic fibrous plaques were found in the...
Aortic valve insufficiency in a one-year-old colt. Aortic insufficiency was suspected in a thin 1-year-old colt with a grade IV/V decrescendo holodiastolic murmur and a bounding arterial pulse. Echocardiographic findings (diastolic fluttering of the septal leaflet of the mitral valve, left ventricular volume overload, and incomplete aortic valve closure) were diagnostic for aortic valve insufficiency. Moderately thick fibrotic aortic valve leaflets were found at necropsy. Fenestrations were found in the aortic and pulmonic valve cusps. Congenital valvular disease may have led to aortic valvular insufficiency in this horse.
Echocardiographic evaluation of equine aortic insufficiency. Echocardiographic evaluation of 23 horses with aortic insufficiency was performed, using M-mode (n = 23) and 2-dimensional real-time echocardiography (n = 14 of 23). Echocardiograms were evaluated for abnormalities of aortic and mitral valves and alterations in motion of these valves. Changes in left ventricular chamber size and function, as well as aortic root size, were evaluated. The presence of other cardiac disease was also evaluated. Horses with aortic insufficiency had significant increases (P less than 0.01) in mean values of left ventricular chamber size, aortic root diameter, and sho...
Systemic and pulmonary haemodynamics in normal neonatal foals. Cardiopulmonary function was studied in 10 full-term healthy foals from birth to 14 days of age. Systemic and pulmonary haemodynamics were recorded in lateral recumbency via indwelling aortic and pulmonary artery catheters. Mean body weight increased from 45.4 +/- 2.4 kg on Day 1 to 70.6 +/- 6.1 kg on Day 14. All foals had a continuous murmur of patent ductus arteriosus for 3-6 days. From Day 1 (12 h old) to Day 14, heart rate increased (89 +/- 4 to 95 +/- 5/min), mean aortic pressure increased (87.7 +/- 1.9 to 100.3 +/- 3.2 mmHg), mean pulmonary artery pressure decreased (38.6 +/- 4.6 to 27.4...
Rupture of an aortic sinus aneurysm in a 15-year-old broodmare. A 15-year-old, Standardbred broodmare with an aortic sinus aneurysm developed rupture of the aneurysm with subsequent rupture of a tricuspid valve chorda tendinae, tricuspid regurgitation, acute right-sided congestive heart failure, and pulmonary thromboembolism. Shunting of blood from the aorta through the ruptured aneurysm into the right ventricle resulted in decreased renal perfusion and acute renal failure. Initially, treatment of the mare with analgesics, fluids, and digoxin resulted in clinical improvement, but the mare's condition deteriorated after 8 days and the mare was euthanatized ...
Acquired cardiovascular disease. This article reviews the etiology, clinical findings, and significance of diseases of the heart valves, myocardium, pericardium, and great vessels of the horse. Each valve is considered separately from the point of view of murmur production. In addition, the role of the cardiovascular system in the etiology of sudden and unexpected death is considered.
Observations on seven cases of mitral insufficiency in the horse. Observations on seven cases of mitral insufficiency are described. Three of the horses had recent histories of cardiac failure and formed a separate group in which there were marked haemodynamic changes which varied in relation to heart rate but were associated with pulmonary hypertension, elevated right ventricular pressure and low peak left ventricular pressure. In the other four horses the heart appeared to be compensating at rest but to be unable to cope with severe exertion. On auscultation, a widespread pansystolic murmur and a prominent third heart sound were characteristic of the left ...
Cardiovascular disease in the equine neonate. Cardiac disease in the equine neonate occurs infrequently. Murmurs are often heard in foals and are not considered significant unless they persist beyond 4 days of age. Congenital cardiac defects are the most common form of primary cardiac disease in the foal, with ventricular septal defects occurring most frequently. Other neonatal foal diseases such as ruptured bladders, white muscle disease, neonatal respiratory distress syndrome, and septicemia have secondary cardiac involvement.
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...
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...
Echocardiographic features of aortic valve endocarditis in a dog, a cow, and a horse. A horse, a cow, and a dog with aortic valve vegetative endocarditis were studied by M-mode echocardiography. Echocardiographic abnormalities of the aortic valve, mitral valve, and left ventricle were observed. These features were identical to those reported in human beings with aortic valve endocarditis. Abnormalities associated with aortic valve endocarditis included irregular thickening of the valve, multiple linear echoes in the aortic root, diastolic prolapse of the aortic vegetation, and diastolic fluttering of a torn aortic valve. Some of these features were found in each animal. The con...
Pulmonary atresia with dextroposition of the aorta and ventricular septal defect in three Arabian foals. Three Arabian males foals were presented with cyanosis, heart murmur, and exercise intolerance, Results of clinical evaluation suggested a tentative diagnosis of ventricular septal defect in conjunction with malformations of the great arteries. Each foal had a poor prognosis and was killed at the owners' requests. At necropsy, the malformed hearts of the three foals were virtually identical. Each heart had a large defect in the upper interventricular septum. The aorta originated from the hypertrophied right ventricle and partially overrode the ventricular septal defect. The aortic ostium was g...
Echocardiography in assessing mitral valve motion in 3 horses with atrial fibrillation. Echocardiography is a non-invasive, safe means of assessing intracardiac structures and their motion. In the normal motion of the mitral valve there is anterior motion noted during atrial systole. In 3 horses with atrial fibrillation the mitral valve motion had no anterior motion to correspond with atrial contractions. Quinidine returned the electrocardiogram of one horse to a sinus rhythm after which echocardiography demonstrated the reappearance of the anterior motion of the mitral valve.
Electrocardiography in the horse. (A report of findings in 138 horses). Over a period of approx. 3 years, electrocardiograms (ECG) were recorded from 138 horses referred as patients to the Medical Clinic. Of these, 22 horses (approx. 16 per cent) has ECG alterations. The 22 ECG's revealed a total of 29 ECG abnormalities. The most frequent ECG alteration was incomplete AV block, that was seen in 9 horses (31 per cent of the ECG abnormalities). Abnormal (i.e. broad, tent-like and, sometimes, inverted) T waves and deviations of the ST segment were seen each in 5 ECG's from 7 horses, 3 of which had both abnormalities which were associated with severe underlying diseas...
Persistent right aortic arch associated with a persistent left ductus arteriosus and an interventricular septal defect in a horse. In this article a description is given of the clinical and postmortem findings of a persistent right aortic arch in association with a persistent left ductus arteriosus and a ventricular septal defect in a horse.
Phonocardiography in the horse: 2. The relationship of the external phonocardiogram to intracardiac pressure and sound. The paper describes observations during individual cardiac cycles on the changing pressures and sounds recorded from the various chambers of the heart and aorta, related to phonocardiograms from an external microphone hand-held over the cardiac area. The majority of the first sound appears to arise from the left side of the heart after the AV valves have closed and the second sound is a consequence of sudden deceleration of blood against already closed semilunar valves. Systolic murmurs at the aortic root may be benign from increased flow and turbulence at the peak of ejection but these may no...
Phonocardiography in the horse: 1. The intracardiac phonocardiogram. Using microtransducers, the intracardiac phonocardiogram was recorded in 8 horses from the right heart and in 6 of them also on the left side. All 4 heart sounds were recorded but not in all sites. Their timing was related to pressure events. Systolic ejection murmurs were recorded in both the pulmonary artery and the aorta. Diastolic murmurs were recorded in 2 horses with aortic regurgitation, with maximum amplitude in the left ventricle. The findings were similar to those reported in man and agree with some of the recent concepts on heart sound production.
Haemodynamics in the horse: 1. Pressure pulse contours. Using a catheter with 2 transducers, one mounted at the tip and one 9 cm proximal to it, enabled transvalval pressure waveforms to be recorded in 8 horses. A simultaneous electrocardiogram acted as a time base. The changing waveforms produced in the chambers of the heart and great vessels are described and related to the events of the cardiac cycle. The effect of second degree AV block, ectopic beats, a pan diastolic murmur and chronic obstructive pulmonary disease are described.
Tetralogy of Fallot and cranial mesenteric arteritis in a foal. A 5 month old colt foal with recurrent pyrexia and a loud pansystolic murmur later developed signs of cardiac failure. Peritoneal fluid and blood samples both demonstrated an extreme leucocytosis and neutrophilia. At post-mortem both a cranial mesenteric arteritis and the congenital cardiac anomaly, Tetralogy of Fallot were found. The detailed clinical and post-mortem findings contributing to the case are described.