Supravalvular mitral stenosis in a cat

A 3-year-old, 4-kg, castrated male domestic shorthair cat presented with signs of progressive respiratory distress. Thoracic radiographs showed pulmonary edema and pleural effusion. Echocardiography revealed a perforate membrane immediately above the mitral valve that divided the left atrium into proximal and distal chambers. The left auricle was proximal to the dividing membrane and connected to the markedly enlarged proximal left atrial chamber, consistent with the diagnosis of supravalvular mitral stenosis (SMS). Position of the obstructing membrane relative to the left auricle distinguishes SMS from cor triatriatum sinister (CTS). In CTS, the left auricle is distal to the dividing membrane and connects to the distal left atrial chamber.     

Double-outlet right atrium in a 9 year-old cat

Double-outlet right atrium (DORA) is a type of atrioventricular septal defect that is described as an extreme leftward deviation of the lower portion of the interatrial septum, resulting in insertion into the atrial wall left and posterior to the mitral orifice. This rare anomaly, which has been reported in humans and only just recently in cats, was identified by transthoracic echocardiography in a 9 year-old cat that was presented for further evaluation of a tachyarrhythmia and cardiomegaly. This case report describes the diagnostic findings in this cat and summarizes the anatomy, classification and clinical consequences of this rare congenital heart defect.     

Symptomatic partial anomalous pulmonary venous connection in a kitten

A 3-month-old intact female American Shorthair cat, with syncope and tachypnea, underwent cardiac examination which identified no heart murmur or gallop. Thoracic radiography disclosed mild generalized enlargement of the cardiac silhouette and a bronchial and interstitial pattern throughout the lungs. Echocardiography identified tubular structures near the left atrium. After agitated saline contrast imaging, persistent left cranial vena cava with unroofed coronary sinus was suspected. Computed tomography angiography showed the right cranial, right caudal and left caudal pulmonary veins draining into the coronary sinus and flowing into the right atrium. The left cranial pulmonary vein drained normally into the left atrium. Partial anomalous pulmonary venous connection (PAPVC) was diagnosed. The kitten was treated with diuretics but died of heart failure 2 months later. Permission for necropsy was not granted. This case represents symptomatic PAPVC in a kitten. Most pulmonary veins were connected abnormally with the coronary sinus. The prognosis was grave because of refractory heart failure.     

Dysplasia of the tricuspid valve in the dog and cat.

Dysplasia of the tricuspid valve in 14 dogs and 13 cats was studied. The clinical, electrocardiographic, radiographic, hemodynamic, angiocardiographic, and pathologic findings were reviewed in each species. Alterations of the tricuspid valve complex included long, thick septal leaflets adhered to the septum; absent or short, stout fused chordae tendineae; hypertrophic fused papillary muscles; insertion of papillary muscles directly into the lateral leaflets; incomplete development of the valvular tissue; and enlargement of the right atrium and ventricle. Additional intracardiac anomalies included malformation of the mitral valve complex (5 dogs and 3 cats), ventricular septal defect (3 dogs and 3 cats), pulmonary stenosis (1 dog and 1 cat), aortic stenosis (1 dog and 1 cat), and persistent left cranial vena cava (1 dog).     

Management of cor triatriatum dexter by balloon dilatation in three dogs

Two dogs, one immature and one adult, were presented with a history of progressive ascites. In a third, immature dog, increasing exercise intolerance had been noted. Echocardiography demonstrated a partition in the right atrium (cor triatriatum dexter) and echocontrast studies documented normal flow from the cranial vena cava into the right atrium and ventricle. A saphenous vein contrast study demonstrated flow from the caudal vena cava into an accessory right atrial chamber (sinus venarum). The sinus venarum communicated with the true right atrium via a small defect in the atrial membrane in one dog, and additionally with the left atrium via a right-to-left shunting foramen ovale in the other dogs. All defects were visualised on angiographic studies by selective catheterisation of the caudal vena cava via the femoral vein. Balloon dilatation of the defect was then performed using a small followed by a larger balloon angioplasty catheter to enlarge the defect in the atrial membrane. Clinical signs improved within days and were sustained in the long-term in all cases.     

Atrioventricular septal defects: Natural history,echocardiographic, electrocardiographic,and radiographic findings in 26 cats

ObjectivesTo evaluate signalment, echocardiographic, electrocardiographic, and radiographic findings as well as natural history in a group of cats with atrioventricular septal defects (AVSD).Animals26 client owned cats.MethodsMedical records were reviewed retrospectively for signalment, morphologic type of AVSD, presence of concurrent congenital heart disease (ConcCHD), diagnostic findings, and natural history.ResultsSeventeen cats had an isolated AVSD; 13/17 had a partial and 4/17 had a complete AVSD. Double outlet right atrium (DORA) was diagnosed in 4/17 cats. Of those with a partial AVSD, 7/13 had an atrial communication while 6/13 had a ventricular communication. Congestive heart failure (CHF) developed in 5/17 cats; all 3 cats diagnosed with a DORA not lost to follow-up developed pulmonary edema. Sudden death was documented in 4/17 (23.5%). The 5 year survival was 53.0% (9/17). Concurrent congenital heart disease was identified in 9/26 cats with 7/9 having a conotruncal abnormality. Electrocardiography was performed in 14 cats with 11/14 diagnosed with a conduction disturbance.ConclusionsOverall the echocardiographic and electrocardiographic findings with AVSD are similar to that seen in humans. Cats may have a higher prevalence than humans of partial AVSD with ventricular communication only as well as a higher prevalence of DORA. Cats with an AVSD have an overall guarded prognosis although some can live for a protracted time.     

Cor triatriatum sinister in a cat

A heart murmur was detected in a five-month-old Persian chinchilla cat. The animal was referred to Nihon University Animal Medical Center where radiographic examination revealed an enlarged heart with dilation of pulmonary arteries and veins and pulmonary oedema. Echocardiography revealed partition of the left atrium, with turbulent blood flow within the left atrium. The patient was placed under continuous care at the facility, but died at seven months of age. Postmortem examination revealed that the left atrium was partitioned by a fibromuscular septum, with a 1 mm diameter perforation, consistent with a diagnosis of cor triatriatum sinister.     

A case of sustained atrial fibrillation in a cat with a normal sized left atrium at the time of diagnosis

This case illustrates an unusual presentation of atrial fibrillation in a 10-year-old male neutered Maine coon. At the time of diagnosis of the arrhythmia the size of the left atrium determined by echocardiography was within normal limits and no structural or functional heart or other systemic disease was identified. Traditionally it has been suggested that the atria must be of a sufficient size in order to sustain atrial fibrillation (multiple wavelet theory) and therefore only cats with significant cardiac disease can attain sufficiently large atria to sustain this arrhythmia. To the author's knowledge this is the first detailed case report of sustained atrial fibrillation in a cat with a normal sized left atrium and no obvious structural heart disease seen on cardiac ultrasound.     

Multiple cardiac anomalies in a cat.

A 7-week-old domestic shorthair cat was examined because of congestive heart failure. Echocardiography and angiography were used to identify multiple cardiac anomalies. Because of the uncorrectable nature of the defects, the cat was euthanatized. Necropsy revealed persistent left vena cava, patent foramen ovale, and a right atrial/left ventricular canal. The right atrioventricular valve was replaced by a small ostium, and no chordae tendinae or papillary muscles were observed around the ostium. The pulmonary trunk originated from the right atrium. The right ventricular free wall was approximately 1 mm thick.     

Presumed congenital Gerbode defect in an American Domestic Shorthair cat

A five-month-old, intact female Domestic Shorthair cat presented to the Kansas State Veterinary Health Center for evaluation of a murmur and exercise intolerance. Physical exam revealed a grade V/VI right, parasternal, holosystolic murmur. On echocardiogram, there was an abnormality in the membranous interventricular septum and tricuspid valve, allowing blood to shunt from the left ventricle to the right atrium. This lesion is consistent with an infravalvular Gerbode defect. The Gerbode defect is a rare, left ventricle-to-right atrial shunt that can be congenital or acquired, and in cats, has only been reported once. At the time of submission, the patient is alive and is maintaining a good quality of life.     

Hypereosinophilic syndrome with cardiac infiltration and congestive heart failure in a cat

Hypereosinophilic syndrome is an uncommon disorder in the cat. It is a heterogeneous group of conditions defined by a persistent hypereosinophilia associated with organ damage directly attributable to tissue hypereosinophilia. A seven-year-old castrated domestic shorthair cat presented to the emergency service for dyspnea. Initial physical examination identified the presence of a grade III/VI systolic left parasternal murmur with no gallop or arrhythmia. A snap N-terminal-pro hormone brain natriuretic peptide was abnormal, and a point-of-care ultrasound revealed mild pleural effusion, scant pericardial effusion, and an enlarged left atrium. There was leukemia (72.35 K/uL, reference range 4.5–15.7 K/uL) predominated by eosinophilia (33.84 K/uL; reference range 0–1.9 K/uL). On echocardiogram, there was concentric hypertrophy of the left ventricular walls with irregular endocardial borders. The left atrium was enlarged with evidence of spontaneous echogenic contrast. The mitral valve was thickened with a vegetative lesion on the anterior leaflet. Despite treatment, the patient experienced cardiopulmonary arrest, and cardiopulmonary resuscitation was unsuccessful. Complete necropsy with histopathology revealed eosinophilic infiltrates in multiple organs and the presence of a severe, acute-on-chronic, fibrinous, and eosinophilic-granulomatous endomyocarditis with mural thrombosis and marked endocardial fibrosis. This case represents an unusual presentation of the hypereosinophilic syndrome in the cat with cardiac involvement and congestive heart failure as a primary clinical sign.     

Patent ductus arteriosus: anatomy and surgery in a cat

A 5-month-old cat with patent ductus arteriosus (PDA) and probable small ventricular septal defect had severe cardiomegaly and congestive heart failure. The cat improved slightly with medical therapy and markedly after surgical closure of the ductus. A 4th left intercostal space thoracotomy gave good exposure. The external anatomy of the PDA was similar to that of a short, wide PDA in dogs; however, the internal aortic orifice was situated more cranial than in dogs, as evidenced by preoperative cardiac catheterization. Examination 1 year later showed marked reductions in heart size and electrocardiographic amplitude. The cat was 1 of 3 with clinically diagnosed PDA at the University of Pennsylvania from 1968 to 1980. The prevalence of PDA in 14,224 cats (0.2/1,000) was significantly less than in 68,049 dogs (4.7/1,000).     

Diagnosis and management of cor triatriatum dexter in a Pyrenean mountain dog and an Akita Inu

Cor Triatriatum Dexter is a rare, congenital cardiac defect in which the right atrium is partitioned into two compartments, effectively creating a triatrial heart. The clinical signs exhibited by the patient usually relate to impeded venous return via the caudal vena cava. The two dogs in this report both displayed ascites from a young age and grew poorly. In both cases the diagnosis was made during echocardiographic examination and was confirmed by angiography. Both dogs were successfully treated by resection of the partitioning membrane within the right atrium, using hypothermia and inflow occlusion to achieve a clear surgical field. Both dogs recovered well, their clinical signs resolved and they have grown to normal adult size.     

Echocardiographic diagnosis of congenital membranous ventricular septal aneurysm in the dog and cat

Membranous ventricular septal aneurysm was diagnosed by echocardiography in 17 dogs and three cats. The aneurysm appeared as a thin membrane protruding into the right ventricle from the margins of a congenital ventricular septal defect (VSD). The aneurysm was intact in nine dogs and two cats and perforated by a small VSD in eight dogs and one cat. Other congenital heart defects were present in seven dogs. In all animals, the aneurysm was an incidental finding observed during echocardiographic examination, and it did not appear to directly cause any cardiac dysfunction.     

Echocardiographic diagnosis of an anomaly of the tricuspid valve in a male pygmy goat.

A 3-year-old male pygmy goat was evaluated because of a grade III/V plateau pansystolic murmur that was auscultated over the tricuspid valve area and a grade II/V plateau pansystolic murmur that was auscultated over the left heart base. Echocardiography revealed a large right atrium and ventricle, an atrial septal defect, and a dysplastic tricuspid valve displaced apically into the right ventricle. Contrast echocardiography and color-flow Doppler echocardiography revealed flow from right to left through the atrial septal defect and severe tricuspid regurgitation. A diagnosis of tricuspid valve dysplasia and severe tricuspid regurgitation was made. This anomaly (Ebstein's anomaly) of the tricuspid valve should be considered in goats that have systolic, with or without diastolic, murmurs over the tricuspic valve. Two-dimensional echocardiography can confirm the diagnosis of the anomaly. The associated tricuspid regurgitation and interatrial right-to-left shunt flow can be detected and semiquantitated by use of contrast, continuous wave, and color-flow Doppler echocardiography.     

Hybrid cutting balloon dilatation for treatment of cor triatriatum sinister in a cat

A hybrid surgical approach and balloon dilatation were performed successfully in a cat with cor triatriatum sinister and clinical signs of congestive heart failure. Left lateral thoracotomy was used to access the heart and cutting balloon followed by standard balloon dilatation were utilized to dilate the perforation in the anomalous left atrial membrane. Clinical signs resolved completely after dilation of the anomalous left atrial membrane. Based upon the outcome of this case, balloon dilatation appears to be a viable treatment option for cats affected with cor triatriatum sinister.     

Partial anomalous pulmonary venous connection in a dog

A 2-year-old male intact Belgian Malinois was presented for exercise intolerance. A grade III/VI left basilar systolic murmur was detected. Echocardiography revealed moderate right atrial and ventricular dilation and increased pulmonic outflow velocity. Thoracic radiographs showed right heart enlargement and a dilated caudal vena cava. In addition, on the left lateral projection, an enlarged aberrant right cranial pulmonary lobar vein was suspected to be diverging ventrally from the course of the right cranial lobar bronchus and inserting more ventrally than normal in the region of the right atrium. A left-to-right pulmonary vascular shunt was suspected, and the patient underwent further diagnostics under general anesthesia. An agitated saline study was positive, suggestive of a concurrent right to left shunt. A right heart catheterization was performed. Angiography was inconclusive. Oximetry testing revealed an increase in oxygen saturation within the right atrium at the level of the caudal cava supportive of a left-to-right shunt in this region. Computed tomography angiography revealed a large single pulmonary vein that anomalously entered into the caudolateral aspect of the right atrium (left-to-right shunt) and was suspicious for a small arteriovenous malformation between the right caudal pulmonary artery and the right pulmonary vein returning to the left atrium (right to left shunt). The patient was diagnosed with a partial anomalous pulmonary venous connection and a possible arteriovenous malformation.     

Pulmonic stenosis and right-to-left atrial shunt in three dogs

Using cardiac catheterization, pulmonic stenosis and right-to-left atrial shunt were diagnosed in 3 young dogs that were evaluated because of weakness, cyanosis, and polycythemia. Injection of contrast material into the caudal vena cava or crossing the atrial septal defect with the catheter tip from the right atrium into the left atrium confirmed the diagnosis. Tetralogy of Fallot, with right-to-left shunt through a ventricular septal defect, is a more common congenital malformation associated with the aforementioned clinical signs. Differentiation between the 2 defects is important, because surgical decompression of the right ventricle will lead to reduction of right atrial pressure and diminishment of the shunt.     

Incomplete atrioventricular canal complicated by cardiac tamponade and bidirectional shunting in an adult dog

An incomplete atrioventricular (AV) canal with bidirectional shunting and cardiac tamponade in a 6-year-old dog was initially diagnosed echocardiographically as a common atrium. The dog failed to respond to medical therapy and was euthanized. Upon necropsy, the defect was confirmed as an incomplete AV canal. A mechanism for the potential sequence of clinical events demonstrated in this dog is proposed.     

Endocardial ossifying myxoma of the right atrium in a cat

Primary cardiac neoplasms are rare in humans and animals. In humans, the most common primary cardiac tumor is the myxoma, which is frequently found in the left atrium. Cardiac myxoma has been reported in the dog but not in the cat. We describe the gross, immunohistochemical, and light microscopic examination of a myxoma in the right atrium of a 6-year-old domestic shorthair cat. Histologically, the tumor consisted predominantly of mesenchymal cells with several foci of bone and cartilage present. The tumor was encapsulated and benign.