Echocardiographic findings in a dog with vegetative bacterial endocarditis (Case report)

Definitive diagnosis of mitral and aortic valvular endocarditis in a dog was based on echocardiograpic findings and was then confirmed by positive blood culture. Abdominal ultrasound examination revealed a renal abcess. This case illustrates that echocardiography associated with abdominal ultrasound has become an essential tool for the diagnosis of bacterial endocarditis and for the detection of sequela or initial source of bacteriemia, while waiting for blood culture results. A short review of echocardiographic and Doppler abnormalities associated with bacterial endocarditis is presented.     

Beating heart mitral valve replacement with a bovine pericardial bioprosthesis for treatment of mitral valve dysplasia in a Bull Terrier

OBJECTIVES: To describe an open, beating heart surgical technique and use of a bovine pericardial prosthetic valve for mitral valve replacement (MVR) in the dog. STUDY DESIGN: Clinical case report. ANIMALS: Male Bull Terrier (17-month-old, 26 kg) with mitral valve dysplasia and severe regurgitation. METHODS: A bovine pericardial bioprosthesis was used to replace the mitral valve using an open beating heart surgical technique and cardiopulmonary bypass. RESULTS: Successful MVR was achieved using a beating heart technique. Mitral regurgitation resolved and cardiac performances improved (left ventricular end-diastolic diameter decreased from 57.6 to 48.7 mm, and left atrium/aorta ratio returned to almost normal, from 1.62 to 1.19). Cardiopulmonary by-pass time and total surgical duration were decreased compared with standard cardioplegic techniques. Surgical recovery was uneventful and on echocardiography 6 months later valve function was excellent. CONCLUSION: Considering the technique advantages (no cardiac arrest, ischemic reperfusion injury, and hypothermia, or the need for aortic dissection and cannulation for administration of cardioplegic solution), short-term mortality and morbidity may be reduced compared with standard cardioplegic techniques. CLINICAL RELEVANCE: Based on experience in this dog, beating heart mitral valvular replacement is a seemingly safe and viable option for the dog and bovine pericardial prosthesis may provide better long-term survival than mechanical prostheses.     

Echocardiographic features of accessory mitral valve tissue presenting left ventricular outflow tract obstruction in a dog

In a 3-year-old Samoyed, aortic bulging was found on radiography during a general check-up. On echocardiography, turbulent flow was found in left ventricular outflow tract (LVOT) with high velocity (6.1 m/s). A linear structure was attached to the interventricular septum and connected to the chordae tendineae reaching the papillary muscle. A part of the structure moved during cardiac cycle, similar to mitral motion. This dog was diagnosed with LVOT obstruction caused by accessory mitral valve tissue (AMVT). This is the first report of AMVT in veterinary medicine. AMVT should be considered as a possible cause of LVOT obstruction in dogs.     

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).     

Brain abscess and bacterial endocarditis in a Kerry Blue Terrier with a history of immune-mediated thrombocytopenia

Objective: To describe a case of multifocal brain abscessation as a sequela from bacterial endocarditis in a dog with a 4‐month history of immune‐mediated thrombocytopenia (ITP) and treatment with immunosuppressive therapies. Case summary: An 8‐year‐old spayed female Kerry Blue Terrier weighing 13 kg was presented for evaluation of progressive neurologic deficits after a 4‐month history of immunosuppressive treatment of ITP. Brain magnetic resonance imaging revealed lesions consistent with multiple central nervous system abscesses and rupture of an abscess into an adjacent ventricle. Staphylococcus species were cultured from blood and cerebral spinal fluid and a vegetative lesion of the mitral valve was identified by echocardiographic examination. Intensive care, intravenous antibiotics, and supportive therapy led to resolution of clinical signs. Resolution of the vegetative lesion on the mitral valve was documented by serial echocardiographic examination. The dog was clinically normal 11 months after treatment. New or unique information provided: Bacterial endocarditis can be an occult infection and difficult to diagnose. Emboli from endocarditis are common, but those that affect the spleen and kidneys are often clinically silent in dogs. This case represents the first report of multifocal brain abscessation (documented with magnetic resonance imaging) as a sequela from bacterial endocarditis.     

Gerbode type defect and third degree atrioventricular block in association with bacterial endocarditis in a dog

Gerbode type defects are rare left ventricular outflow tract–right atrial communications in people that may be congenital or acquired; they have been reported only once previously in dogs. Acquired forms in humans have been reported secondary to bacterial endocarditis, trauma, and valve replacement surgery, among other causes. We report a case of left ventricular outflow tract to right atrium and right ventricle communications (Gerbode type defect) in association with aortic and tricuspid valve bacterial endocarditis in a geriatric dog. The dog also developed third degree atrioventricular block and had underlying subaortic stenosis. The authors hypothesize that the Gerbode type defect in this case was acquired secondary to invasion and destruction of the membranous interventricular septum due to bacterial endocarditis.     

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.     

Chronic renal failure in an English bull terrier with polycystic kidney disease

An entire female English bull terrier, aged five years and one month, was diagnosed with polycystic kidney disease by renal ultrasonography. It had thickening and abnormal motion of the mitral valve on 2D and M mode echocardiography, and left ventricular outflow tract obstruction, characterised by turbulence in the left ventricular outflow tract and elevated aortic blood flow velocity, detected by colour flow and spectral Doppler echocardiography, respectively. Two years later, haematology, serum biochemistry and urinalysis data suggested the presence of compensated renal failure. The dog was euthanased at 10 years and eight months of age, with haematology, serum biochemistry and urinalysis data Indicating decompensated chronic renal failure. Postmortem examination confirmed polycystic kidney disease, chronic renal disease, mitral and aortic valvular myxomatous degeneration, and mixed mammary neoplasia. This case demonstrates that bull terriers with polycystic kidney disease may develop associated chronic renal failure.     

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.     

Diagnosis of right coronary artery to right atrial fistula in a dog using two-dimensional echocardiography

A five-year-old boxer dog developed cardiac murmurs, complete heart block and car-diomegaly associated with vegetative bacterial endocarditis. Using two-dimensional echocardiography, vegetative lesions of the aortic valves and extension of the vegetations into the proximal right coronary artery and adjacent atrial septum were identified. The vegetation within the atrial septum appeared as a cavitated mass which protruded into the right atrium. Fistulae within the atrial septal vegetation permitting communication between the coronary artery and right atrium were observed with colour Doppler echocardiography. The dog died despite medical treatment. Post mortem examination confirmed the echo-cardiographic findings. Vegetative endocarditis with invasion into the right coronary artery and atrial septum producing fistulae and communication with the right atrium has not been reported previously in dogs. Doppler echocardiography proved useful in demonstrating the abnormal anatomy, intraluminal fistular blood flow and its communication with the right atrium.     

Echocardiography and Surgery in a Dog With Left Atrial Rupture and Hemopericardium

Endocardial splitting and left atrial rupture were diagnosed in a dog with mitral regurgitation that experienced the sudden onset of collapsing episodes, weakness, depression, labored breathing, and weak pulses. Thoracic radiographs showed a rounded cardiac silhouette with prominent left atrium consistent with hemopericardium due to left atrial rupture. Two-dimensional echocardiography confirmed the presence of severe mitral valve disease, pericardial fluid, and a laminated blood clot caudal to the left ventricle. A sterile emergency thoracotomy was performed, the hemopericardium and blood clot were removed, and the rupture site in the left atrium was repaired with reinforced sutures. The dog recovered from surgery but died the next day, presumably from a ventricular arrhythmia.     

Pathologic and clinical features of infectious endocarditis

Infectious endocarditis is a systemic disease associated with high morbidity and mortality. Clinical recognition and effective management is challenging, but insights can be gleaned from relevant pathologic features. Risk factors include subaortic stenosis, possibly certain other congenital anomalies, and bacteremia. Auscultation can provide clues regarding valvular involvment, particularly when a diastolic left basilar murmur of aortic valve regurgitation is present. Aortic valve vegetations and insufficiency may also alter femoral arterial pulse characteristics. Echocardiography may facilitate diagnosis, particularly with aortic valve lesions, but may not be able to distinguish between small mitral valve vegetations and early chronic degenerative valve disease. Vegetative lesions develop along edges of valve closure on the ventricular aspect of the aortic valve and the atrial surface of atrioventricular valves. They may extend across valve leaflet, from valves to adjacent left atrial endocardium, interventricular or interatrial septum, or chordae tendineae. Vegetations can be friable and frequently embolize to spleen, kidney, and left ventricle — often before clinical recognition of the disease. Valvular insufficiency develops as a consequence of valvular vegetations, necrosis, perforation, or rupture of the chordae tendineae. Histopathologic appearance varies with respect to duration of disease and antimicrobial therapy. These factors influence the amount of necrotic material, blood clot, fibrin, and inflammatory cells which make up the vegetations. Bacteria are not always identified in valvular lesions, especially following antibacterial therapy, but may be detected in other organs. Common sequellae include congestive heart failure, sepsis, arrhythmias, and systemic organ infarction.     

Pathology of bartonella endocarditis in six dogs

In a 5-year retrospective study of dogs presenting to the Veterinary Medical Teaching Hospital at the University of California, Davis, there were 31 histologic diagnoses of valvular endocarditis. By polymerase chain reaction (PCR) amplification of embedded valvular tissue, Bartonella organisms were exclusively associated with 6 out of 31 cases (19%). Confirmed Bartonella cases involved the aortic valve alone (five out of six) or in combination with the mitral valve (one of six). Microscopic features of Bartonella endocarditis were compared with valves from non-Bartonella endocarditis and with valvular change unrelated to infectious agents (endocardiosis). Features of Bartonella endocarditis included a combination of fibrosis, mineralization, endothelial proliferation, and neovascularization with variable inflammation. None of these features is specific; however, the combination is distinct both from endocarditis caused by culturable bacteria and from endocardiosis. Ultrastructural analyses revealed both extracellular and intraendothelial bacteria. Clinical history, serology, and PCR are currently necessary to establish an etiologic diagnosis of Bartonella endocarditis.     

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.     

Clinical, echocardiographic, and Doppler imaging characteristics of mitral valve stenosis in two dogs.

Mitral stenosis was diagnosed noninvasively by echocardiography and Doppler imaging in 2 Bull Terriers. Two-dimensional echocardiography revealed severe atrial and moderate left ventricular dilatation; severely reduced mitral valve opening excursion; doming of the cranial mitral valve leaflet into the left ventricle during diastole; thickened, nodular cranial mitral valve leaflets; and reduced mitral valve orifice. M-mode echocardiographic findings additionally indicated greatly diminished mitral valve E to F slope and abnormal caudal mitral valve leaflet motion. Color flow Doppler imaging revealed bright bursts of color with aliasing originating from the stenotic mitral valve orifice, extending into the left atrium during systole, and into the left atrium during diastole. Spectral Doppler recordings revealed transvalvular mitral valve gradients and prolonged pressure half-times. Necropsy performed on 1 dog revealed extremely thickened, nodular, and stiff mitral valves with short, thickened, and fused chordae tendineae. The diagnosis of mitral valve stenosis was easily facilitated with diagnostic ultrasonography.     

Echocardiographic detection of tricuspid atresia in two foals

M-mode, 2-dimensional, and contrast echocardiographic studies were used to detect tricuspid atresia in 2 foals. M-mode echocardiographic findings included a small right ventricle, large left ventricle, large mitral valve excursion, large left atrium (foal 2), dropout of the cranial aspect of the aortic root, and a thick band of echoes in the tricuspid valve region. These findings were confirmed by 2-dimensional echocardiography. In addition, a large right atrium, persistent foramen ovale, ventricular septal defect, and large mitral valve apparatus were imaged. One foal also had a thick right atrial wall. Contrast echocardiography confirmed the intracardiac flow of blood from right to left atrium and then to the left ventricle, followed by simultaneous opacification of the right ventricle and aorta. The use of these echocardiographic techniques enables accurate antemortem diagnosis and prognosis of tricuspid atresia in the foal.     

Malformation of the canine mitral valve complex.

Twenty-nine dogs, including 13 Great Danes and 5 German Shepherd Dogs and averaging 7.3 months age, were diagnosed clinically and radiographically as having mitral regurgitation. Alterations of the mitral valve complex included enlarged anulus; short thick leaflets, with an occasional cleft; short and stout or long and thin chordae tendineae; upward malposition of atrophic or hypertrophic papillary muscles; insertion of one papillary muscle directly into one or both leaflets; and diffuse endocardial fibrosis, occasionally with jet lesions in te left atrium. Other cardiac anomalies included dysplasia of the tricuspid valve (5 dogs), patent ductus afteriosus (2 dogs), aortic stenosis (2 dogs), and ventricular septal defect (1 dog).     

Bacterial aortic valvular endocarditis associated with subaortic stenosis

The clinical and pathological findings in four young adult rottweiler dogs with subaortic stenosis and secondary bacterial endocarditis of the aortic valve are described. The four dogs, two males and two females, ranged in age from 18 months to three years. Three had three- to four-week histories of lethargy, anorexia, weight loss and intermittent coughing that progressively worsened. Bacterial aortic valvular endocarditis was diagnosed on the basis of physical examination and radiographic and ultrasound findings. Subaortic stenosis was not suspected clinically, but was found at necropsy. The fourth dog was known to have a subaortic stenotic ring at six months of age and developed clinical signs similar to the other dogs four weeks before euthanasia. Bacterial aortic valvular endocarditis and a subaortic stenotic ring were found at necropsy. It is suspected that the turbulence in blood flow caused by the stenotic rings damages the endocardium of the aortic valve, predisposing to the development of endocarditis.     

DOPPLER ECHOCARDIOGRAPHY IN THE NORMAL DOG: PART II

Doppler echocardiography was used to determine blood flow velocities in the normal canine heart. The areas examined were the mitral valve, left atrium, tricuspid valve, right atrium, aortic valve, left ventricular outflow tract, pulmonic valve and right ventricular outflow tract. This study then statistically evaluated the influence of breed, age, sex, heart rate, mass and various interactions of these factors on the cardiac flow values determined. Mass and heart rate had the most significant effect on the various determinations with decreasing mass and increasing heart rates generally resulting in increasing peak and mean velocities. The pulmonary artery was statistically judged as being the flow area most susceptible to such influences. Comparisons were made between pulsed and continuous wave Doppler for peak velocities over the four valve areas with only aortic flow, as measured from the left caudal view, showing a significant difference between the two techniques. Mitral flow as compared to tricuspid flow showed a statistically significant difference between peak late diastolic velocities only. The ratio of early mitral diastolic flow to late mitral diastolic flow was always greater than one. Pulmonary flow showed a number of statistically significant differences when compared to aortic flow.