Lecture 12: Acquired Valvular & Endocardial Disease

What are the causes of mitral valve regurgitation?

What is MMVD?

thickening and elongation of the valve leaflets, leads to valvular insufficiency (regurgitation) and volume overload of the left atrium & ventricle

75-80% of all canine heart disease (small dogs < 45 lbs and older dogs)

What are the symptom differences between early and progressive MMVD and MMVD with CHF?

Early: Asymptomatic; incidental left apical systolic murmur

Progressive: Cough (esp. night), exercise intolerance, tachypnea, restlessness

CHF: Dyspnea, syncope, collapse, +/- ascites if bivent failure)

How is MMVD diagnosed (not including echo)?

PE:

• Left apical systolic murmur

• +/- tachycardia, arrhythmia, dyspnea, crackles, weak pulses

ECG: ± sinus tachycardia, arrhythmias, large LA/LV patterns

Thoracic radiographs:

• Cardiomegaly over time (LA), with L bronchus compression

• LAA bulge at 3 o’clock on DV (“Bow-legged cowboy” sign = separation of mainstem bronchi)

• Lateral projection - tracheal elevation and left atrial bulge caudodorsal aspect of heart

• Pulmonary venous congestion

• Interstitial to alveolar pattern (pulmonary edema) if CHF

How does MMVD appear on an echo?

• Thickened mitral leaflets

• Mitral valve prolapse

• Mitral regurgitation +/- tricuspid regurgitation

• LV volume overload → LV, LA dilation - La:Ao ratio > 1.6 is significant

• May develop chordae tendinae rupture

• May develop pericardial effusion (If endocardial splitting and then LA tear)

• Less often develop pleural effusion

What can explain peracute worsening symptoms of MMVD?

ruptured chordae tendinae

What is the typical presentation of ruptured chordae tendinae?

acute LCHF

What are the clinical syndromes of MMVD?

• No clinical signs (asymptomatic murmur or click)

• Cough: Left mainstem bronchus compression, Early CHF

• Left sided congestive heart failure: Dyspnea due to pulmonary edema

• Ruptured chordae tendinae (acute L-CHF): Incidence ~15% (up to 70% of dogs with severe CHF)

• Syncope: Vasovagal syncope, tussive syncope, arrhythmia, pulmonary hypertension

• Endocardial split/LA tear: Cardiac tamponade

What are the big 4 of MMVD treatment?

• Furosemide

• Spironolactone

• Pimobendan

• ACE Inhibitor

What is the new combo therapy for MMVD?

cardalis = spironolactone/benazepril combination

What is stage A MMVD?

Dogs at higher than average risk for developing heart failure but without any apparent structural abnormality (ie. no murmur) → no treatment

What is stage B MMVD?

Structural abnormality (ie. MMVD) but no clinical signs of heart failure

Stage B1: Asymptomatic dogs with MV regurgitation from MMVD not severe enough to meet criteria used to trigger treatment

Stage B2: Asymptomatic dogs with MV regurgitation from MMVD severe enough to result in cardiac remodeling (LA/LV enlargement) sufficient to recommend treatment

What are the treatment options for stage B MMVD?

B1: No drug or dietary treatment is recommended → Reeval by echocardiography or radiography in 6-12 months

B2:

• Pimobendan

• Diet - mild sodium restriction, adequate protein/calories, highly palatable

• Angiotensin converting enzyme inhibitors (ACEI)

• Beta blockade is not recommended routinely to delay the onset of heart failure in dogs in Stage B2, regardless of heart enlargement

• Spironolactone is not recommended for routine use to delay the onset of heart failure although a pilot study suggests this approach should be used

What is stage C MMVD?

MMVD severe enough to cause current or past clinical signs of heart failure Hospitalized (Acute) vs Home (Chronic)

How is stage C MMVD diagnosed?

• ECG, BP, Thoracic Radiographs, Echocardiogram, NT-proBNP

• Normal/near normal [NT-proBNP] in dog w/ cough, dyspnea, or exercise intolerance = NOT CHF!!!

How is stage C MMVD treated?

Hospital/Acute:

• Furosemide, Oxygen, Pimobendan, Sedation PRN, Centesis PRN, Nursing care, Dobutamine/Sodium nitroprusside/ACEi/Nitroglycerin all PRN

Home/Chronic:

• Furosemide, Pimobendan, ACEi, Spironolactone

• Cough suppressants? Bronchodilators?

• Continue diet per Stage B, promote appetite PRN, adjust K/Mg PRN, omegas?

• Monitor BUN/Cr/Lytes!

• Inc. in resting RR above normal has best predictive value for impending clinical decompensation

What is stage D MMVD?

Patients have clinical signs of failure refractory to standard treatment for Stage C heart failure from MMVD

How is stage D MMVD treated?

Hospital/Acute:

• Furosemide higher dose or Torsemide (0.1-0.2 mg/kg q12h-q24h or approx 5%-10% of the current furosemide dosage to deliver a furosemide-equivalent dose)

• Centesis PRN, More potent afterload reduction, More Pimobendan?

• Sildenafil PRN if pulmonary hypertension

Home/Chronic:

• Furosemide/Torsemide, Hydrochlorothiazide?, Pimobendan, ACEi, Spironolactone, More afterload reduction, Cough suppressants? Bronchodilators?

• Continue diet per Stage B, promote appetite PRN, adjust K/Mg PRN, omegas?

• Monitor BUN/Cr/Lytes!

• Increase in resting respiratory rate above normal baseline has the best predictive value for impending clinical decompensation

What is the prognosis for MMVD?

• B1: Years, may never progress

• B2: 3.5 years to CHF with Pimobendan

• C: 6-12 months

• D: Weeks to months

What is the most common type of endocarditis?

valvular endocarditis

What are the complications associated with bacterial endocarditis?

• thickening/fibrous valvular changes

• vegetative lesions may create stenosis or insufficiency

What are the risk factors for bacterial endocarditis?

• Pre-existing valvular disease (esp. congenital SAS)

• Immunosuppressive drugs (28%)

• Middle aged, intact male large breed dogs (90%)

• Recent surgery

• Recent IV catheter placement

• Antimicrobial use (74%, often inadequate or inappropriate)

• Allergic factor (proposed for equine endocarditis)

What are the cardiac effects of bacterial endocarditis?

Mitral valve:

• Mitral regurgitation (systolic regurgitant quality murmur)

• Mitral stenosis (diastolic murmur)

• Left-sided CHF

Aortic valve:

• Aortic regurgitation (Diastolic murmur & bounding arterial pulses)

• Aortic stenosis (systolic ejection murmur)

• Left-sided CHF

Pulmonic and tricuspid valve:

• Tricuspid &/or pulmonic stenosis or insufficiency

• Right-sided CHF

• Pulmonary thromboembolism

What are the systemic effects of bacterial endocarditis?

• Pyelonephritis

• UTI

• Meningitis

• Septic arthropathy

• Myocarditis

• Immune mediated GN or polyarthritis

• Thrombosis can lead to infection or infarction (“bland thrombus”) - spleen, kidney, left ventricle, lungs, CNS, GI tract

What clinical scenarios are associated with bacterial endocarditis?

• CHF

• fever of unknown origin

• multisystemic signs

• organ embolism

What are the common clinical findings associated with bacterial endocarditis?

• fever

• leukocytosis

• cardiac murmur

• lameness

• lethargy, anorexia depression

What diagnostic testing should be performed if suspecting bacterial endocarditis?

• bartonella testing

• arthrocentesis

• blood and urine cultures

What are the echocardiographic findings of bacterial endocarditis?

• Thick, asymmetric, shaggy, hyperechoic vegetative valvular lesions

• Oscillating, vibratory, or mobile valvular lesions

• Cardiac chamber enlargement or hypertrophy

• Valvular regurgitation or stenosis

• Diagnostic accuracy 80-90%

• Transesophageal echocardiography: Better definition of structures at heart base, Improves diagnostic accuracy

How is bacterial endocarditis treated?

• Antibiotic based on culture & sensitivity or serology

• IV antibiotics for the first 5-14 days

• Broad spectrum antibiotics

• Oral antibiotics for 4 to 8 weeks

corticosteroids contraindicated and reduce survival

What is the prognosis of bacterial endocarditis?

Median survival 2 months (0-1,028 days)

Aortic valve 3 days vs. mitral valve 476 days

Worse prognosis if:

• CHF is already present at time of diagnosis

• Aortic valve is affected

• Gram negative sepsis

• Renal failure or increased creatinine

• Thrombocytopenia

• Thromboembolic complications

• Azotemia

• Treated with corticosteroids

• Large animal species? Cats?