(1) Normal to mild left ventricular wall thickening
(2) Diastolic ventricular dysfunction (3) Biatrial enlargement
(4) Mitral regurgitation (5) Pleural effusion (6) Pericardial effusion
b. Electrocardiography: Similar to hypertrophic cardiomyopathy
c. Thoracic radiographs: Similar to hypertrophic cardiomyopathy 6. Treatment. Medical management
a. "-Blocker or calcium channel blocker b. ACE inhibitor c. CHF (1) Oxygen (2) Diuretics (3) Pleurocentesis (4) Abdominocentesis d. Antiarrhythmic therapy e. Thromboembolism (1) Aspirin, clopidogrel (2) Pain medication (3) Physical therapy 7. Prognosis
a. Mild: Favorable; rarely develop clinical signs b. Moderate: May develop clinical signs c. Severe: Develop clinical signs; prognosis
is poor
I. Arrhythmogenic right ventricular cardiomyopathy in cats
1. Characterized by fatty or fi brofatty infi ltration of the right ventricle
2. Clinical signs a. May be normal b. Exercise intolerance c. Lethargy
d. Right-sided heart failure: Cough, dyspnea, ascites e. Syncope f. Sudden death g. Weight loss h. Decreased appetite 3. Physical examination
a. Systolic sternal murmur b. Gallop
c. Arrhythmia
d. Normal pulse quality
e. Normal to pale mucous membrane color
f. Dyspnea g. Crackles h. Ascites
i. Hepatosplenomegaly j. Jugular venous distension k. Hypothermia
4. Diagnosis
a. Echocardiogram
(1) Right ventricular enlargement (2) Right atrial enlargement (3) Tricuspid regurgitation (4) Pleural effusion (5) Pericardial effusion b. Electrocardiography. Ventricular arrhythmias c. Thoracic radiographs
(1) Normal in cats with an early stage of the disease
(2) Generalized cardiomegaly (3) Pleural effusion
5. Treatment. Medical management a. Positive inotropic support b. ACE inhibitor c. CHF (1) Oxygen (2) Diuretics (3) Pleurocentesis (4) Abdominocentesis d. Antiarrhythmic therapy 6. Prognosis poor
II. Valvular endocardiosis
A. Commonly acquired heart disease in middle-aged to older dogs
B. Occurs with less frequency in cats
C. Result of myxomatous degeneration of the atrioventricular valves (mitral valve more frequently than tricuspid valve)
D. Progression to heart failure is highly variable E. Acute decompensation occurs with chordae
tendinae rupture, left atrial rupture, and the onset of arrhythmias
F. More common in small breed dogs but does occur in large and giant breeds
G. Common breeds: Cavalier King Charles spaniel, dachshund, miniature poodle, cocker spaniel, Pomeranian, Miniature schnauzer, Boston terrier, Chihuahua
H. Clinical signs: May be normal; exercise intoler- ance, lethargy, anorexia, weight loss, left or right heart failure (cough, dyspnea, ascites), syncope, sudden death
I. Physical examination
1. Systolic left apical murmur with mitral regurgitation
2. Systolic right heart murmur with tricuspid regurgitation
3. Mid-systolic click 4. Normal pulse quality 5. Arrhythmia
6. Gallop 7. Dyspnea
8. Signs of right-sided heart failure if tricuspid endocardiosis or pulmonary hypertension a. Ascites
b. Positive hepatojugular refl ex c. Jugular venous distension J. Diagnosis
1. Echocardiogram
a. Left atrial enlargement b. Left ventricular enlargement
c. Normal, increased, or decreased systolic function
d. Normal left ventricular wall thickness e. Thickened valve leafl ets
f. Prolapse or fl ail of the valve leafl ets g. Mitral regurgitation
h. Normal transaortic and transpulmonic velocities
i. Signs of right heart enlargement with tricus- pid endocardiosis or pulmonary hypertension (1) Right atrial enlargement
(2) Right ventricular enlargement (3) Tricuspid regurgitation (4) Pulmonic regurgitation (5) Pulmonary artery enlargement 2. Electrocardiography
a. Sinus arrhythmia b. Sinus tachycardia
c. Tall R waves in lead II suggestive of left ventricular enlargement
d. Wide P waves in lead II suggestive of left atrial enlargement
e. Tall P waves in lead II suggestive of right atrial enlargement
f. Supraventricular or ventricular premature beats
g. Atrial fi brillation or fl utter 3. Thoracic radiographs
a. Normal in dogs with an early stage of the disease
b. Left ventricular enlargement c. Left atrial enlargement
d. Mainstem bronchial compression e. Enlarged pulmonary veins f. Pulmonary edema
g. Signs of right-sided heart disease with tricuspid endocardiosis or pulmonary hypertension
(1) Right atrial enlargement (2) Right ventricular enlargement (3) Pulmonary artery enlargement (4) Pleural effusion
4. Blood pressure
a. Normal systolic pressure
b. May be decreased in severe cases with reduced cardiac output
c. May be increased with comorbidities such as renal or endocrine disease
5. Serum biochemistry panel and electrolytes K. Treatment. Medical management
1. Preclinical
a. No medication shown to delay the progres- sion of the disease
b. ACE inhibitors frequently prescribed c. The use of "-blockers is under investigation 2. CHF
a. Oxygen b. Diuretics
c. Positive inotropic support d. Nitroglycerin ointment e. ACE inhibitor
f. Pleurocentesis g. Abdominocentesis
3. Mainstem bronchial compression
a. Cough suppressant such as hydrocodone, butorphanol, or dextromethorphan b. Bronchodilator such as theophylline
4. Systemic hypertension: Afterload reducers such as hydralazine, amlodipine, or ACE inhibitors
5. Antiarrhythmic therapy
6. Surgery: Valvular repair or replacement; high degree of diffi culty, requires special equipment, costly, not readily available L. Prognosis: Dependent on progression and sever-
ity of the disease. Cavalier King Charles spaniels may have a faster rate of progression
III. Valvular endocarditis
A. Incidence is higher in large breed dogs and dogs with congenital heart disease (aortic stenosis and ventricular septal defects)
B. Most common valves affected are aortic, mitral C. Most common infectious organisms
1. Escherichia coli 2. Staphylococcus aureus 3. Streptococcus spp. 4. Corynebacterium
5. Bartonella vinsonii more common in culture-negative endocarditis
D. Embolism of the kidney, spleen, liver, gastrointesti- nal (GI) tract, brain and limbs have been reported E. Clinical signs: May be normal; exercise intolerance,
lethargy, left-sided heart failure (cough, dyspnea), syncope, sudden death, anorexia, weight loss F. Physical examination
1. Systolic left apical murmur if mitral regurgitation
2. Diastolic left basilar murmur if aortic regurgitation
3. Systolic left basilar murmur if aortic stenosis 4. Systolic right sternal murmur if ventricular
septal defect 5. Gallop 6. Arrhythmia
7. Normal to increased pulse quality 8. Pulse defi cits
9. Normal to pale mucous membrane color 10. Dyspnea
11. Painful joints resulting from septic arthritis 12. Fever
G. Diagnosis
1. Echocardiogram
a. Left ventricular dilation b. Left atrial enlargement
c. Normal to increased left ventricular wall thickness. Increased with aortic stenosis d. Mitral regurgitation
e. Aortic regurgitation
f. Normal to increased transaortic velocities g. Vegetative valvular lesions
h. Thickened aortic valve leafl ets 2. Electrocardiography
a. Tall R waves in lead II suggestive of left ventricular enlargement
b. Wide P waves in lead II suggestive of left atrial enlargement
c. Ventricular arrhythmias
d. Supraventricular premature beats e. Atrial fi brillation
3. Thoracic radiographs
a. Normal in dogs with an early stage of the disease