Multiple cardiac anomaly in sheep: a case study and review of the literature

A multiple cardiac anomaly in sheep is presented to show how complicated the result of abnormal development can be. The heart of a 12-hour-old sheep was fixed in 8% formaldehyde solution and subsequently dissected by an anatomical method, and the abnormalities were recorded on digital pictures. The abnormal anatomy is described and compared with the simple developmental anomalies. Developmental abnormalities were found in the distal portion of the bulbus, the aortic arches and the interatrial septum. A special type of the double-outlet right ventricle was observed, which was not a real double-outlet ventricle because it occurred in combination with pulmonary atresia. Coarctation of the aorta was seen, the ductus arteriosus was absent, and there were five vessels originating from the aortic arch instead of one vessel seen in normal cases, as a result of the abnormal development of the aortic arches.     

Double-outlet right ventricle with an intact interventricular septum and concurrent hypoplastic left ventricle in a calf

A 3-day-old Hereford heifer calf presented for evaluation of lethargy and dyspnea, with persistent hypoxia despite supplemental oxygen therapy. A grade III/VI right apical systolic murmur was noted during cardiac auscultation. Echocardiography revealed a double-outlet right ventricle with an intact interventricular septum and concurrent hypoplastic left ventricle and tricuspid valve dysplasia. Post-mortem examination revealed additional congenital anomalies of ductus arteriosus, patent foramen ovale, and persistent left cranial vena cava. This report illustrates the use of echocardiographic images to diagnose a double-outlet right ventricle with an intact interventricular septum and a hypoplastic left ventricle in a calf.     

AORTO-CARDIAC FISTULAS IN SEVEN HORSES

This report describes the history, clinical, electrocardiographic and echocardiographic findings, treatment, outcome, and post-mortem findings in seven horses with aorto-cardiac fistula. Affected horses included 5 stallions, one gelding and one mare; 2 each of the Thoroughbred, Arabian and Standardbred breeds and one Thoroughbred-cross with a mean ± s.d. age of 12 ± 4 years, range 6–18 years. The presenting sings were acute distress (four horses), exercise intolerance (two horses) and the lesion was detected during a routine examination in one horse. Five horses had monomorphic ventricular tachycardia on admission and one other had a history of this arrhythmia. Five horses had a characteristic continuous murmur loudes in the right fourth intercostal space. Echocardiography (six horuses) and/or post-mortem examination (four horses) revealed the horses had aorto-cardiac fistulas arising from the right aortic sinus in all five horses in which the site was recorded. Two horses had ruptured aneurysmall dilatations of the aortic wall at this site. Fistulas extended into the right ventricle in four horses; the right atrium in two horses, the left ventricle in one horse, and five horses had dissecting tracts in the septal myocardium. Horses survived for periods ranging from 24th to 4 years. Aorto-cardiac fistula should be considered in the differential diagnosis for horses presenting with acute distress, bounding arterial pulse, a right-sided continuous murmur and/or monomorphic ventricular tachycardia, particularly in middle-aged or older stallions. Echocardiography is the technique of choice for confirming the diagnosis and demonstrating accompanying cardiac changes.     

Ventricular septal defects in the horse

Clinical, echocardiographic, and right-side cardiac catheterization data were collected in 6 horses with ventricular septal defects. The defects were confirmed by necropsy in 5 horses. On echocardiography, the cardiac dimensions were normal in 3 horses and enlarged in 2 others. A step-up in partial oxygen pressure between right atrium and right ventricle suggested a left-to-right shunt in 3 of the 4 horses catheterized. In 1 foal, a small defect without PO2 step-up was documented by angiocardiography. The oxymetry and pressure data were compared with previous cases from the reviewed literature, and the importance of pressure measurements to rule out concomitant defects was emphasized.     

Pulmonary hypertension as a cause of atrial fibrillation in young horses: four cases (1980-1989)

Four young horses of various breeds and suffering from atrial fibrillation died of heart failure. All had markedly high pulmonary arterial pressure, right-sided cardiomegaly, and lack of histologic lesions in the right atrium or pulmonary parenchyma. Three horses had hypertrophy and/or necrosis of the tunica media of the pulmonary vasculature. Clinical signs of disease, physiologic data, and pathologic findings indicated that these horses had primary pulmonary hypertension with secondary right-sided cardiac ventricular hypertrophy and dilatation, atrial fibrillation, and heart failure.     

A cardiac rhabdomyoma in a Guinea pig

A guinea pig (9-week-old) that had been placed in a control group for a pharmacological test was found to have a single nodule on the surface of the right ventricular wall. In a transverse section of the heart after fixation, a whitish mass was found that extended from the subendocardium to the subepicardium of the right ventricular wall. Histopathological examination revealed a spongy network consisting of vacuolated spaces in the myocardium of the right ventricle extending to the myocardium and subepicardium of the right atrium. The vacuolated space was PAS-positive. Immunohistochemical examinations revealed that the lesions contained striated fibers that were positive for anti-desmin and anti-myoglobin. Electron micrographs revealed the lesions resulting in affected striated muscle fibers and accumulations of many glycogen granules. Based on the findings, the lesions were diagnosed as a cardiac rhabdomyoma. This is the first report of application of immunohistochemical examinations to diagnosis of cardiac rhabdomyoma in the guinea pig.     

Day-to day variability of cardiac pressure values in horses measured with right heart catheterization on 3 consecutive days

In the present study, a right heart catheterisation was carried out on three consecutive days in 17 healthy horses to evaluate the day-to-day variability of cardiac pressure values. Cardiac pressure values were measured in the right atrium, the right ventricle, the pulmonary artery, and the pulmonary capillaries (pulmonary artery wedge pressure). Additionally it was examined wether the cardiac pressure variability was influenced by the heart rate and if there are differences between trained and untrained horses. Beside the coefficient of variances, statistical analysis with assessment of variance components were carried out. Therefore the variation between repeated measurements at one day and within one horse, and the variation between repeated measurements over three days and within the horses (day to day intraindividual variation) as well as the variation between the horses (interindividual variation) were taken into account. The absolute interindividual variance of the pressure values and the heart rate was between 0.4 and 19.6 at all day and for all horses. Between trained and untrained horses the variation of the pressure values and the heart rate was lower than in the trained horses. A significant difference between trained and untrained horses was seen in right atrial mean pressure (p < 0.001) and right atrial diastolic pressure (p < 0.005). The coefficient of variances of the mean heart rate was 11.8%. The coefficient of variances of the different pressure values ranged between 13.1 (mean pulmonary artery pressure) and 46.4% (right ventricular pressure). By splitting the variances, 54.4-78.9% of the variation was caused by the effect of days, 6.2-30.7% of the variation was caused by the effect of horses and 12.5-23% of the variation was caused by the repeated measurements at the different days. In sumary the results shows that nearly all of the pressure values had a low effect of days on the variation, thus cardiac pressure measurements at one day seem to be sufficient.     

Double-outlet right ventricle associated with discordant atrioventricular connection and dextrocardia in a cat

The prevalence of congenital cardiac disease in cats varies from 0.2 to 1 per cent, with males being more affected than females. This is probably an underestimate due to the fact that not all affected kittens are presented. Discordant atrioventricular connection (where the morphological right atrium connects to the morphological left ventricle, and the morphological left atrium connects to the morphological right ventricle) is an uncommon condition in humans and, to the authors' knowledge, has not to date been described in animals. The association between this anomaly and the double-outlet right ventricle (where both great arteries arise entirely or partially from the morphological right ventricle) is extremely rare in children. This report describes a case of a cat which presented with this association of cardiac defects.     

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.     

Influence of subclinical pulmonary findings on cardiac parameters in Icelandic horses

In the present study we examined, if in Icelandic horses an increase in heart and/ or breathing rate is physiological and breed dependend or a sign of a pulmonary or cardiac disease. Therefore we examined 37 Icelandic horses with the prereport of being healthy. During clinical lung examination four horses showed symptoms of a pulmonary disease like increased breathing rate and enforced breathing at rest. These horses were excluded from the study. The other 33 horses were clinically normal. 17 of these horses were unridden (untrained) and 16 horses were regularly worked (trained). After clinical examination in all horses analysis of arterial blood gas, endoscopy with tracheo- bronchial secret analysis and radiographic examination of the lung were carried out. Additionally electro- and echocardiographic examinations and standardised exercise tests with determination of heart and breathing rate as well as plasma lactate values were performed in all horses. During electro- and echocardiographic examination no pathological findings were observed. In total 22 of the 33 horses showed abnormal lung findings. Seven horses had mild signs of RAO and 15 horses had mild signs of interstitial bronchitis. Three horses had additional pulmonary haemorrhage. Eleven out of the 33 horses showed no abnormal lung findings. The breathing rate at rest differed not significantly between horses with (21 +/- 1/min) or without (23 +/- 2/min) pulmonary findings. The heart rate also did not differ significantly between horses with (39 +/- 1/min) or without (42 +/- 1/min) pulmonary findings. In contrast to this the trained Icelandic horses with abnormal pulmonary findings had significantly higher heart rates (p = 0.01) and significantly lower breathing rates (p = 0.009) compared to those without abnormal pulmonary findings. During echocardiography Icelandic horses with abnormal pulmonary findings had significantly larger left atrial diameter (without abnormal pulmonary findings: 82 +/- 7 mm, with abnormal pulmonary findings: 90 +/- 8 mm, p = 0.02). Compared to the untrained Icelandic horses (5.4 +/- 2 mmol/l) the trained horses showed significantly lower plasma lactate values (3.1 +/- 2 mmol/l, p = 0.001) immediately after exercise. After exercise the icelandic horses with abnormal pulmonary findings had significantly higher breathing rates (p < 0.05) and longer recovery periods (30 minutes) than horses without abnormal respiratory findings (15 minutes). Recovery of heart rate after exercise showed no differences between groups.     

Aortic root disease in four horses

Clinical findings in 4 horses with aortic root disease are described. Three of the horses had aneurysms of the right aortic sinus, and in 2 of the 3, the aneurysm ruptured, creating a fistula between the aorta and right ventricle. One of these horses had had a murmur since birth, and the aortic sinus aneurysm may have been a congenital anomaly. In a second horse, the aneurysm may have been an acquired condition that developed secondary to chronic aortic regurgitation. Another horse had a large subendocardial hematoma associated with dissection of blood from the aorta to the interventricular septum because of a tear in the aortic root near the right aortic sinus. Ventricular ectopy and signs of abdominal pain were the most common initial signs in these horses.     

THE APPLICATION OF TECHNETIUM-99m HEXAMETHYLPROPYLENEAMINE OXIME (99mTc-HMPAO) LABELED WHITE BLOOD CELLS FOR THE DIAGNOSIS OF RIGHT DORSAL ULCERATIVE COLITIS IN TWO HORSES

The application of 99mTc-HMPAO labeled white blood cells to support the diagnosis of right dorsal ulcerative colitis was studied in two horses with a history and clinical signs consistent with phenylbutazone toxicity. These images were compared to a reference horse unaffected by right dorsal ulcerative colitis. Blood was collected aseptically in heparinized syringes from the patients for in vitro white blood cell (WBC) radiolabeling. The buffy coat was separated out and radiolabeled with 99mTc-HMPAO. The radiolabeled blood was re-injected i.v. and four images of the right and left side of the patient's abdomen were acquired at 4 hours and 20 hours post-injection. Results of the nuclear study revealed no abnormal findings in the abdomen at the four-hour post-injection images in any horse. Images obtained 20 hours post-injection revealed a linear uptake of radiolabeled WBCs in the right cranioventral abdomen in the region of the right dorsal colon in both horses with right dorsal ulcerative colitis. The reference horse had no radiopharmaceutical uptake in this region. This nuclear imaging study was a rapid, non-invasive method to identify right dorsal colon inflammation. These findings not only supported the diagnosis of right dorsal ulcerative colitis, but also facilitated appropriate medical management of each horse.     

Severe cardiac malformation with secondary polycythemia in a 5-month old calf

A 5-month old female Red-Holstein calf in poor condition was presented with a history of reduced appetite, respiratory disease and collapse. Clinical examination revealed an elevated heart rate and pronounced cyanosis of the mucous membranes. Heart and lung auscultation were normal. A complete blood count revealed profound polycythemia with severely increased values for packed cell volume, hemoglobin concentration and erythrocyte count. Cardiac ultrasonography revealed abnormal position of the great vessels with two arteries located in the right ventricle output tract and a high ventricular septum defect (VSD). Intracardial pressure and blood gas measurements confirmed pressure overload in the right heart, a left-to-right shunt through the VSD and a right-to-left-shunt leading to hypoxemia and secondary polycythemia. Based on poor prognosis, the animal was euthanized. Post-mortem examination confirmed the results of the further investigations conducted to determine the cause of polycythemia in this calf.     

Myocardial Function of Horses Under Sedation with Romifidine Using Two-Dimensional Speckle Tracking

Two-dimensional speckle tracking echocardiography (2DST) provides the assessment of the left ventricle deformation parameters strain (St) and strain rate (SR). The objective of this study was to evaluate St and SR under the influence of romifidine in healthy horses and horses affected with heart disease. The study subjects were 45 privately owned horses. Valvular insufficiencies were identified by color Doppler in 21 out of 45 horses. Dimensional changes were identified in 13 of these 21 horses. These dimensional changes included dilatations of the left ventricle (130 ± 8.95 mm) and/or the left atrium (141 ± 4.8 mm). The other 24 horses were without echocardiographic findings and had normal heart dimensions. Based on clinical signs, echo-, and electrocardiographic examinations, 24 horses were categorized as group 1 (healthy), 13 as group 2 (heart disease without dimensional changes), and 8 as group 3 (heart disease with dimensional changes). The radial St and SR were assessed in the left ventricular free wall and the interventricular septum using 2DST. After application of romifidine, a significant reduction of St and the systolic peak of SR were found in all three groups. Group 3 showed the most significant reduction of these parameters (41.5%). The reduction of St and SR under romifidine showed a reduced myocardial function, which is more obvious in horses with cardiac dilatation. It can be assumed that heart disease with myocardial dilatation leads to decreasing myocardial function, which becomes more obvious after romifidine application and of clinical importance in horses with severe heart disease and cardiac dilatation.     

Retrospective evaluation of episodic collapse in the horse in a referred population: 25 cases (1995-2009)

Background: Episodic collapse in horses has equine welfare and human safety implications. There are, however, no published case series describing this syndrome. Objectives: To characterize the cause and outcomes for horses referred for investigation of episodic collapse. Animals: Twenty‐five horses referred for investigation of single or multiple episodes of collapse. Methods: Retrospective study. Clinical records from the Dick Vet Equine Hospital, University of Edinburgh from November 1995 to July 2009 were searched using the following keywords: collapse, collapsing, fall, syncope. Collapse was defined as an incident in which the horse lost postural tone with or without progression to recumbency and with or without loss of consciousness. Long‐term follow‐up information was obtained by telephone conversation with the owner. Results: A final diagnosis was reached in 11 cases, namely cardiac arrhythmia (4), right‐sided heart failure (1), hypoglycemia (2), generalized seizures (2), and sleep disorder (2). A presumptive diagnosis was reached in 8 cases, namely neurocardiogenic syncope (5), exercise‐induced pulmonary hemorrhage (2), and generalized seizures (1). No diagnosis was reached in 6 cases despite comprehensive investigations. Three horses were euthanized at presentation. Treatment was attempted in 9 horses with 6 cases having successful outcome before discharge. Follow‐up information was available for 14 of 19 horses discharged from the hospital. Only 1 of these horses was observed to collapse after discharge. Conclusions and Clinical Importance: Definitive diagnosis was more likely to be reached in cases with multiple episodes of collapse. Horses in which 1 episode of collapse occurred did not necessarily collapse again.     

Aortic rupture and aorto‐pulmonary fistulation in the Friesian horse: Characterisation of the clinical and gross post mortem findings in 24 cases

Reasons for performing study: In horses, aortic sinus of Valsalva aneurysms or tears in the aortic root are well‐recognised conditions in breeding stallions, often leading to sudden death. A more uncommon form of aortic rupture, located proximal to the ligamentum arteriosum has been reported in 3 Friesian horses. Objectives: The purpose of this study was to phenotypically characterise aortic rupture and aorto‐pulmonary fistulation in Friesian horses in terms of clinical and post mortem data based on 24 cases. Methods: Friesian horses that were diagnosed with aortic rupture and aorto‐pulmonary fistulation over a period of 13 years (1997–2010) at the Department of Equine Sciences of Utrecht University (n = 15) and Wolvega Equine Hospital (n = 9), were included in this study. Case history, results of clinical examination and gross post mortem findings were screened and analysed. Results: Some cases were found dead without prior symptoms, but in several cases signs such as recurrent colic, peripheral oedema and sustained tachycardia were present for several weeks prior to cardiac failure. Clinical examination during hospitalisation revealed increased rectal temperature, peripheral oedema and increased jugular pulse with a bounding arterial pulse. In the majority of horses an aortic rupture of the aortic arch near the ligamentum arteriosum, concurrent with a circumferential cuff of perivascular haemorrhage and aorto‐pulmonary fistulation, was found at post mortem examination. Conclusions: Aorto‐pulmonary fistulation in conjunction with aortic rupture is more common in Friesians than previously estimated. In some cases findings demonstrate a progressive pathology rather than acute cardiac failure and sudden death. An appropriate approach is necessary during post mortem examination of the heart in order not to overlook the diagnosis. Potential relevance: Equine practitioners should realise that in Friesian horses presented with a history of recurrent false colic, coughing, sustained tachycardia and/or peripheral oedema, aortic rupture and aorto‐pulmonary fistulation should be included in the differential diagnosis.     

Influence of detomidine on echocardiographic function parameters and cardiac hemodynamics in horses with and without heart murmur

30 warmblood horses were examined before and after sedation with 20 micrograms/kg BW detomidine, to determine changes of cardiac function parameters, using B-mode, M-mode and Doppler echocardiography. 15 horses showed a heart murmur, but no clinical signs of cardiac heart failure, 15 horses had neither a heart murmur nor other signs of cardiac disease. After sedation with detomidine we could recognise a significant increase of end-diastolic left atrium diameter, an increase of end-systolic left ventricular diameter and aortic root diameter. The end-systolic thickness of papillary muscle and interventricular septum showed a decrease. Fractional shortening and amplitude of left ventricular wall motion was decreased after sedation. The mitral valve echogram revealed a presystolic valve closure and an inflection in the Ac slope (B-notch) in xy horses before sedation. Both increased after sedation with detomidine. Doppler echocardiography showed a decrease of blood flow velocity and velocity time integral (VTI) in the left and right ventricular outflow tract after sedation. Regurgitant flow signals were intensified following sedation in xy horses, especially at the mitral valve.     

Congestive heart failure in horses: 14 cases (1984-2001)

OBJECTIVE: To identify clinical signs, underlying cardiac conditions, echocardiographic findings, and prognosis for horses with congestive heart failure. DESIGN: Retrospective study. ANIMALS: 14 horses. PROCEDURE: Signalment; history; clinical signs; clinicopathologic, echocardiographic, and radiographic findings; treatment; and outcome were determined by reviewing medical records. RESULTS: All 14 horses were examined because of a heart murmur; tachycardia was identified in all 14. Twelve horses had echocardiographic evidence of enlargement of 1 or more chambers of the heart. Other common clinical findings included jugular distention or pulsation, crackles, cough, tachypnea, and ventral edema. Nine horses had signs consistent with heart failure for > 6 days. Underlying causes for heart failure included congenital defects, traumatic vascular rupture, pericarditis, pulmonary hypertension secondary to heaves, and valvular dysplasia. Seven horses were euthanatized after diagnosis of heart failure; 5 were discharged but were euthanatized or died of complications of heart disease within 1 year after discharge. The remaining 2 horses were discharged but lost to follow-up. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that congestive heart failure is rare in horses. A loud heart murmur accompanied by either jugular distention or pulsation, tachycardia, respiratory abnormalities (crackles, cough, tachypnea), and ventral edema were the most common clinical signs. Echocardiography was useful in determining the underlying cause in affected horses. The long-term prognosis for horses with congestive heart failure was grave.     

Advances in echocardiography

Before the development of echocardiography, cardiac disease in the horse was diagnosed if a loud heart murmur (grade III-IV/VI or louder) and clinical signs of congestive heart failure (coughing, edema, venous distention, jugular pulsations) were detected on physical examination. Arrhythmias that persisted during and after exercise also indicated cardiac disease, which could be characterized electrocardiographically. Electrocardiography, thoracic radiography, angiography, cardiac catheterization, and oximetry could add only small pieces of information about the heart. M-mode echocardiography provided the first "window" with which to evaluate the heart and its intracardiac structures, albeit an ice-pick one-dimensional view. With M-mode echocardiography, the diameter of the aorta at the valves, the left ventricle, right ventricle, and left atrial appendage, as well as the thickness of the interventricular septum and left ventricular free wall, could be measured. Motion and thickness of the tricuspid, mitral, and aortic valves could be assessed, but only in a one-dimensional plane. Two-dimensional echocardiography provided an added dimension, resulting in visualization of all the intracardiac structures, aorta, and pulmonary artery. Two-dimensional echocardiography became the diagnostic technique of choice for the evaluation and characterization of congenital cardiac disease in critically ill neonates, as well as in adult horses. Two-dimensional echocardiography also improved the ability to diagnose valvular regurgitations, characterize valvular lesions (bacterial endocarditis, ruptured chorda tendineae), myocardial function (segmental wall motion abnormalities), atrial size, mass lesions (endocarditis, neoplasia, and thrombi), and pericardial effusion. Information about blood flow was obtained using contrast echocardiography but was limited to certain cardiac abnormalities (congenital cardiac defects and tricuspid regurgitation). This information about blood flow was limited to the detection of positive or negative contrast jets. Comprehensive information about blood flow was lacking until the application of Doppler echocardiography to equine cardiology. Pulsed-wave and color flow Doppler echocardiography resulted in precise localization of the abnormal blood flow and semiquantitation of the shunt flow or regurgitant jet. Color flow Doppler echocardiography sped up the localization and semiquantitation of the jet in many instances and provided some information about blood flow velocity in the enhanced and variance modes. The peak velocity of jets can be determined using continuous-wave Doppler echocardiography. This value then can be used to estimate pressure difference between cardiac chambers or to calculate cardiac output noninvasively if angles parallel to flow can be obtained. Thus, information about cardiac size, function, and blood flow can be combined to diagnose cardiac disease in horses and to formulate a prognosis for life and performance.     

Echocardiographic evaluation of cardiac tamponade in dogs before and after pericardiocentesis: four cases (1984-1986)

The echocardiographic (M-mode and 2-dimensional) features (before and after pericardiocentesis) of 4 dogs with pericardial effusion and clinical evidence of cardiac tamponade were reviewed. M-Mode echocardiography revealed pericardial effusion, with exaggerated swinging motion of the heart and abnormal septal motion in all 4 dogs. In each case, 2-dimensional echocardiography demonstrated right ventricular diastolic free-wall collapse. Three dogs had right atrial diastolic collapse as well. Clinical signs improved, and right ventricular and right atrial diastolic collapse subsided after pericardiocentesis. Two-dimensional echocardiographic features of right atrial and ventricular collapse were used as indicators for determining the presence of cardiac tamponade.