Cardiovascular Diseases and Drugs

What are the 4 heart chambers?

R atrium, R ventricle, L atrium, L ventricle

What does the R atrium do?

receives deoxygenated blood from body (vena cava)

What does the R ventricle do?

pumps deoxygenated blood to lungs (pulmonary artery)

What does the L atrium do?

receives oxygenated blood from lungs (pulmonary vein)

What does the L ventricle do?

pumps oxygenated blood to body (aorta)

Describe the right side of the heart’s blood contents and pressure

blood: low O2, high CO2

pressure: low (short distance to lungs)

Describe the left side of the heart’s blood contents and pressure

blood: high O2, low CO2

pressure: high (far distance to body)

What is involved in electrical conduction of the heart?

SA node, AV node, Bundle of His, Purkinje fibers

What is an electrocardiogram (ECG)

measures electrical activity of heart at skin surface

What is the P wave

contraction (depolarization) of atria

What is the QRS complex

contraction of ventricles; repolarization of atria (hidden by vent activity)

What is the T wave

repolarization of ventricles

What is heart failure

not a heart attack; returning blood is not pumped fast enough to meet body’s needs

What are the 2 causes of heart failure

Myocardial (heart muscle) dysfunction

Circulatory failure

What are causes of myocardial heart failure

cardiomyopathy, myocarditis, taurine deficiency in cats

What are causes of circulatory heart failure

hypovolemia (shock, hemorrhage, dehydration), anemia, valvular dysfunction, congenital shunts or defects

What is congestive heart failure

when failing heart leads to fluid congestion (in lungs and in body)

How common is Dilated Cardiomyopathy (DCM) in dogs

one of the most commonly acquired heart diseases in dogs

When is Dilated Cardiomyopathy (DCM) commonly seen?

seen in older large/giant breeds

What happens to the heart with Dilated Cardiomyopathy (DCM)

heart chambers dilate because heart wall becomes thin, weak, and flabby

What does Dilated Cardiomyopathy (DCM) cause?

causes decreased CO and increased blood left in heart after systole

What are the clinical signs for Dilated Cardiomyopathy (DCM)?

giant / large breed dogs; older (4-10 years)

exercise intolerance

R sided failure: ascites / abdominal distention, hepatomegaly, weight loss

L sided failure: coughing, pulmonary edema, syncope

What will a PE on a dog with Dilated Cardiomyopathy (DCM) look like?

weakness, depression, hypokinetic femoral pulse from low CO, pulse deficits, jugular pulses, HR 150-200+ bpm

How is Dilated Cardiomyopathy (DCM) diagnosed

x-rays may show dilated heart

ultrasonography will show dilated heart chambers

ECG - widened / large QRS and P waves, rhythm disturbances

What can be used as treatment for dogs with Dilated Cardiomyopathy (DCM)

diuretics to decrease fluid buildup - furosemide

digoxin - increase strength of contraction, increase CO2

nitroglycerin x 24-48 hours

OXYGEN

vasodilators - enlaopril, etc.

pimobendan - + inotrope, increases survival

What information should be told to clients with a dog with Dilated Cardiomyopathy (DCM)?

fatal disease (6 months to 2 years) - SUDDEN DEATH

more prevalent in large breeds

diet - decrease Na intake

minimal exercise

What are the signs of feline Dilated Cardiomyopathy (DCM)

older, mixed breed (Siamese, Burmese, Abyssinian)

dyspnea, tachypnea, inactivity, anorexia

acute lameness / paralysis (rear legs)

pain / lack of circulation in affected limbs (no pulse due to thromboemboli)

What will the PE of a cat with Dilated Cardiomyopathy (DCM) look like

HR variable (fast, normal, slow), systolic heart murmur, gallop rhythm, + / - arrythmia, hypothermia, increased CRT, tachypnea, quiet lung sound (if pleural effusion), crackles (if pulmonary edema), hypokinetic femoral pulses, + / - posterior paresis / paralysis

What can be used as treatment for cats with Dilated Cardiomyopathy(DCM)

oral taurine supplement (250-500 mg/d)

furosemide

oxygen

digoxin

aspirin or heparin - prevent thromboemboli

vasodilator; decrease vascular resistance (hydralazine)

What information should be told to owners with a cat with Dilated Cardiomyopathy (DCM)?

most dangerous time is first 2 weeks of treatment

if the cat responds to taurine treatment, good px

unresponsive to taurine treatment, poor long-term px