Spontaneous closure of a traumatic acquired Gerbode defect in a dog

A one-year-old female English Springer Spaniel with no previous history of cardiac disease presented to the Queen's Veterinary School Hospital following a blunt traumatic incident with an acquired, direct Gerbode defect and associated third-degree atrioventricular block. Two months after the initial incident, follow-up echocardiography showed a nearly closed Gerbode defect with just trivial residual flow. A 24-h Holter monitor indicated second-degree atrioventricular block with occasional junctional tachycardia. A reassessment 22 months later confirmed spontaneous closure of the previously acquired traumatic Gerbode defect, with 2:1 second-degree atrioventricular block. The dog remained clinically asymptomatic, and free of treatment. To our knowledge, this is the first reported case of spontaneous closure of a previously acquired traumatic Gerbode defect in a dog.     

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.     

Fossa ovalis tear causing right to left shunting in a Cavalier King Charles Spaniel

Left atrial tear is an infrequent sequela of severe mitral regurgitation due to myxomatous mitral valve degeneration. Interatrial septal tear due to mitral regurgitation causing a left-to-right shunt is uncommon. Right to left shunting secondary to acute interatrial septal tear is very rarely reported in the human literature, and has not been reported in the veterinary literature in a dog. This case describes the clinical, radiographic, echocardiographic, gross pathologic, and histopathologic features of a dog presented in acute respiratory distress secondary to acute onset right to left shunting through the interatrial septum. This was later documented to be due to a tear in the septum secondary to tricuspid regurgitation and pulmonary hypertension. The presence of an acquired right to left shunting atrial septal defect is of clinical and prognostic significance, and should be considered in cases of acute respiratory distress.     

Pulmonary artery compression in a Thoroughbred colt due to a mediastinal abscess

In the case presented, a young horse was referred for further evaluation based on a presumptive diagnosis of pulmonic valve endocarditis, bronchopneumonia and a cranial mediastinal abscess based on thoracic ultrasound, echocardiography and clinical signs. However, further echocardiographic evaluation revealed that the abscess was compressing the right ventricular outflow track causing outflow obstruction, a murmur associated with right ventricular outflow tract obstruction (acquired pulmonic stenosis) and right ventricular hypertrophy. Vegetative endocarditis was not present. Medical management was unsuccessful, but surgical drainage and long‐term antimicrobial therapy were effective and the horse returned to a successful racing career.     

Left ventricular outflow tract to left atrial fistula associated with endocarditis in a dog

A one-year-old, intact male, 28-kg, mixed-breed dog developed neurological episodes consistent with emboli. An acquired III/VI holosystolic heart murmur was ausculted in the mitral area, and valvular endocarditis with pulmonic and aortic insufficiency were noted at echocardiographic examination. An abnormal communication (i.e., fistula) between the left ventricular outflow tract (LVOT) and the left atrium adjacent to the mitral valve annulus was noted with Doppler imaging and confirmed with angiography. Infective valvular endocarditis was confirmed based on two of three blood cultures being positive for Staphylococcus intermedius. In humans, a sequela to infective endocarditis of the aortic or mitral valve, or both, is rupture of the mitral-aortic intervalvular fibrosa, resulting in a communication between the LVOT and the left atrium. This is the first report of this sequela in the dog.     

Trifoliate left atrioventricular valve with and without intact septal structures in four dogs: echocardiographic findings and surgical repair

Trifoliate left atrioventricular (AV) valve with common atrioventricular junction is considered part of the spectrum of atrioventricular septal defect. This valve morphology is typically associated with defects in the AV septum resulting in communication at the atrial or ventricular level, but has also been described as an isolated defect in the setting of a common AV junction without AV septal defect. Trifoliate left AV valve exhibits a line of apposition between the bridging leaflets that is directed toward the inlet interventricular septum, distinguishing it from isolated mitral valve cleft in which the orientation of the bridging leaflets are toward the left ventricular outflow tract. The echocardiographic findings of four dogs with trifoliate left AV valve are described; two with intact septal structures and two with large ostium primum defects. Three dogs underwent open surgical repair using different approaches depending on the presence or absence of a septal defect. One of these underwent concurrent surgical repair for right AV valve dysplasia. One dog with intact septal structures underwent interventional closure of a concurrent patent ductus arteriosus. Current terminology associated with trileaflet left AV valve malformations is reviewed.     

Stenting of the right ventricular outflow tract in 2 dogs for palliation of dysplastic pulmonary valve stenosis and right-to-left intracardiac shunting defects

Two dogs with severe dysplastic pulmonary valve stenosis and right-to-left shunting defects (patent foramen ovale, perimembranous ventricular septal defect) underwent palliative stenting of the right ventricular outflow tract and pulmonary valve annulus using balloon expandable stents. One dog received 2 over-lapping bare metal stents placed 7 months apart; the other received a single covered stent. Both procedures were considered technically successful with a reduction in the transpulmonary valve pressure gradient from 202 to 90 mmHg in 1 dog and from 168 to 95 mmHg in the other. Clinical signs of exercise intolerance and syncope were temporarily resolved in both dogs. However, progressive right ventricular concentric hypertrophy, recurrent stenosis, and erythrocytosis were observed over the subsequent 6 months leading to poor long-term outcomes. Stenting of the right ventricular outflow tract is feasible in dogs with severe dysplastic pulmonary valve stenosis, though further study and optimization of the procedure is required.     

Surgical correction of a partial atrioventricular septal defect with a ventricular septal defect in a dog

Echocardiography of a dog with a cardiac murmur revealed an ostium primum septal defect, a ventricular septal defect, and mitral valve malformation with regurgitation. The mitral valve and tricuspid valve were separated and displaced at the same level as the ventricular septum. The mitral valve had a cleft in the septal cusp. Cardiac catheterization and angiocardiography showed a left-to-right shunt and a "goose-neck sign," which indicated an elongated left ventricular outflow tract. The diagnosis of a partial atrioventricular septal defect with ventricular septal defect was made. Surgical correction was successfully performed under extracorpo-real circulation using a cardiopulmonary bypass system.     

Aortic endocarditis associated with a perforated septal membranous aneurysm in a boxer dog

Perimembranous ventricular septal defect is a common congenital heart disease in the dog. It can partially or completely close with age by development of a membranous ventricular septal aneurysm. Aortic endocarditis is a reported complication of ventricular septal defect and membranous ventricular septal aneurysm in human beings. This report describes a case of aortic endocarditis associated with a membranous ventricular septal aneurysm perforated by a small ventricular septal defect in a boxer dog.     

ECHOCARDIOGRAPHIC APPEARANCE OF FLAIL AORTIC VALVE IN A DOG WITH INFECTIVE ENDOCARDITIS

A 4-year-old female Boxer was suffering from aortic valve endocarditis with perforation of the right coronary cusp resulting in a flail aortic cusp and subsequent acute aortic insufficiency. This flail aortic cusp was observed on M mode and two-dimensional endocardiograms as a free linear echostructure in the left ventricular outflow tract. Although rarely observed, a free linear echostructure seems more specific of a flail aortic valve than a shaggy echostructure, which can represent a free moving vegetation and thus be confusing. Severe acute aortic insufficiency resulted in an uncommon abnormal mitral valve motion in the absence of early mitral diastolic opening. The absence of early mitral valve opening was thought to be a consequence of coupled aortic regurgitation, reduced left ventricular compliance, and presumably delayed mitral valve opening secondary to coronary artery occlusion. An exaggerated septal diastolic dip accounted for the decreased transmitral inflow. All the usual contractility parameters were within normal range; subsequently, mitral valve motion alterations seems to be more reliable indicators of left ventricular dysfunction during acute aortic insufficiency.     

Dynamic left ventricular outflow tract obstruction secondary to hypovolemia in a German Shepard dog with splenic hemangiosarcoma

Dynamic left ventricular outflow tract obstruction (DLVOTO) is a common condition in cats and humans. In this case report, a dog is described with DLVOTO secondary to severe intra-abdominal hemorrhage caused by a hemangiosarcoma. The dog was a 9-year-old, 35.7-kg, spayed female German Shepard dog that presented with a history of tachypnea and collapse. A Levine II/VI systolic murmur was present at the heart base. Abdominal ultrasonography revealed a splenic mass and a large amount of ascites. Echocardiography showed a reduced left ventricular diameter and an increased aortic velocity caused by systolic anterior motion (SAM) of the mitral valve apparatus. The heart murmur and the SAM were resolved after treatment including a splenectomy and a blood transfusion.     

Isolation of methicillin-resistant Staphylococcus lugdunensis in a dog with endocarditis

A 4-year-old male castrated Borzoi dog presented on referral for evaluation of pleural effusion, ventricular arrhythmias, and suspected dilated cardiomyopathy. Echocardiogram identified several masses along the chordae tendineae, as well as a long the annulus of the mitral valve. A blood culture was positive for methicillin resistant Staphylococcus lugdunensis. The dog was also positive for Bartonella DNA on PCR testing. Aggressive antibiotic therapy was instituted. However, the dog continued to have recurrent pleural effusion and progressive azotemia. The dog was euthanized 39 days after diagnosis. Necropsy confirmed the presence of intracardiac abscesses, thrombosis and endocarditis. S. lugdunensis is a recently identified rare cause of endocarditis in humans characterized by intracardiac abscess formation, highly destructive valvular lesions preferentially affecting the mitral valve and a high mortality rate. This is the first reported case of S. lugdunensis isolation in a dog with endocarditis.     

Left ventricular outflow tract obstruction caused by a congenital accessory mitral valve leaflet and treated by open-heart surgery in a young dog

A 3-month-old Shetland sheepdog presented with a loud ejection murmur and exercise intolerance. Echocardiography revealed an accessory mitral valve leaflet, characterised by a valve-like structure separate from the mitral valve seen in the subaortic region of the ventricular septum. The left ventricular outflow tract was partially obstructed with a pressure gradient of 12 mmHg. Accessory mitral valve leaflet resection and mitral valvuloplasty were performed during open-heart surgery. Histology performed on the membrane-like structures were indicative of fibrous connective tissues. Postoperative echocardiography confirmed removal of the valve-like structure with resolution of the left ventricular outflow tract obstruction. The pressure gradient was decreased to 4.6 mmHg. The dog was in good condition and no further treatment was required 5 months after surgery. Both cardiac troponin I and NT-proBNP were markedly decreased. In this dog, surgical resection combined with mitral valve plasty resolved the left ventricular outflow tract obstruction and the clinical signs.     

Recommendations for Standards in Transthoracic Two-Dimensional Echocardiography in the Dog and Cat

Recommendations are presented for standardized imaging planes and display conventions for two-dimensional echocardiography in the dog and cat. Three transducer locations ("windows") provide access to consistent imaging planes: the right parasternal location, the left caudal (apical) parasternal location, and the left cranial parasternal location. Recommendations for image display orientations are very similar to those for comparable human cardiac images, with the heart base or cranial aspect of the heart displayed to the examiner's right on the video display. From the right parasternal location, standard views include a long-axis four-chamber view and a long-axis left ventricular outflow view, and short-axis views at the levels of the left ventricular apex, papillary muscles, chordae tendineae, mitral valve, aortic valve, and pulmonary arteries. From the left caudal (apical) location, standard views include long-axis two-chamber and four-chamber views. From the left cranial parasternal location, standard views include a long-axis view of the left ventricular outflow tract and ascending aorta (with variations to image the right atrium and tricuspid valve, and the pulmonary valve and pulmonary artery), and a short-axis view of the aortic root encircled by the right heart. These images are presented by means of idealized line drawings. Adoption of these standards should facilitate consistent performance, recording, teaching, and communicating results of studies obtained by two-dimensional echocardiography. (Journal of Veterinary Internal Medicine 1993; 7:247–252. Copyright © 1993 by the American College of Veterinary Internal Medicine.)     

Surgical correction of subaortic stenosis via right ventriculotomy and septal resection in a dog

After 2 years of medical management with a beta-adrenoreceptor blocking agent, a 30-month-old castrated male Golden Retriever with subaortic stenosis was treated surgically because of progression of its condition. In an attempt to achieve complete relief of the left ventricular outflow obstruction, a modified Konno procedure consisting of right ventriculotomy and septal myectomy from the infundibular portion of the right ventricle was performed; this combination of procedures allowed wide resection of the septal portion of the left ventricular outflow obstruction. Two years after surgery, the mass of the dog's left ventricle had decreased and the peak calculated pressure gradient across the aortic valve had decreased to 40 mm Hg, compared with a preoperative value of 240 mm Hg; at that evaluation, the dog had gained weight and was able to play normally. It is suggested that use of this modified approach to the outflow tract may have a positive effect on long-term survival time in dogs with subaortic stenosis.     

Mitral valve dysplasia in a cat causing reversible left ventricular hypertrophy and dynamic outflow tract obstruction

A 6-month-old male European shorthair cat was examined because of a 2/6 systolic left apical cardiac murmur. Echocardiography revealed severe concentric left ventricular hypertrophy and severe dynamic left ventricular outflow tract obstruction (pressure gradient of 85 mmHg) caused by systolic anterior motion (SAM) of the septal mitral valve leaflet. After 2 months of oral treatment with atenolol, the cardiac murmur had disappeared. Echocardiography showed only slight thickening of the interventricular septum and resolution of the pressure gradient. The cat was discharged and its owner was advised to continue atenolol lifelong. Echocardiographic findings of a combination of left ventricular concentric hypertrophy and dynamic left ventricular outflow tract obstruction can be caused by hypertrophic obstructive cardiomyopathy (HOCM) or mitral valve dysplasia in the absence of hypertension and fixed aortic stenosis. In the case of HOCM, left ventricular hypertrophy is the primary process. In the case of mitral valve dysplasia, systolic anterior motion of the mitral valve is the primary problem, which leads to dynamic left ventricular outflow tract obstruction and ultimately to left ventricular concentric hypertrophy, due to pressure overload. If the left ventricular outflow tract obstruction is reduced with an oral beta-receptor blocker the secondary left ventricular hypertrophy may resolve. This would not happen in the case of hypertrophic obstructive cardiomyopathy. To the best of the authors' knowledge, this is the first documented case of severe dynamic left ventricular outflow tract obstruction and severe left ventricular hypertrophy in a cat successfully treated with oral atenolol.     

RECOMMENDATIONS FOR STANDARDS IN TRANSTHORACIC TWO-DIMENSIONAL ECHOCARDIOGRAPHY IN THE DOG AND CAT*

Recommendations are presented for standardized imaging planes and display conventions for two-dimensional echocardiography in the dog and cat. Three transducer locations (“windows”) provide access to consistent imaging planes: the right parasternal location, the left caudal (apical) parasternal location, and the left cranial parasternal location. Recommendations for image display orientations are very similar to those for comparable human cardiac images, with the heart base or cranial aspect of the heart displayed to the examiner's right on the video display. From the right parasternal location, standard views include a long-axis four-chamber view and a long-axis left ventricular outflow view, and short-axis views at the levels of the left ventricular apex, papillary muscles, chordae tendineae, mitral valve, aortic valve, and pulmonary arteries. From the left caudal (apical) location, standard views include long-axis two-chamber and four-chamber views. From the left cranial parasternal location, standard views include a long-axis view of the left ventricular outflow tract and ascending aorta (with variations to image the right atrium and tricuspid valve, and the pulmonary valve and pulmonary artery), and a short-axis view of the aortic root encircled by the right heart. These images are presented by means of idealized line drawings. Adoption of these standards should facilitate consistent performance, recording, teaching, and communicating results of studies obtained by two-dimensional echocardiography.     

DOPPLER ECHOCARDIOGRAPHY IN THE NORMAL DOG: PART I VELOCITY FINDINGS AND FLOW PATTERNS

This study examined the blood flow velocities and flow patterns in the normal dog using pulsed wave spectral Doppler echocardiography in eight areas of the heart. Two breeds of dogs, aged between 8 and 112 weeks and of both sexes, were used. The dogs were fully conscious and no drugs were used. The areas examined were the mitral valve, left atrium, tricuspid valve, right atrium, aorta, left ventricular outflow tract, pulmonary valve and the right ventricular outflow tract. The peak and mean velocities, direction of flow and whether flow was systolic or diastolic was determined for each of these flow areas. Additionally each of these waveforms were described. Aortic flow was also measured from the thoracic inlet by continuous wave Doppler.