Disease of the Heart

What are the primary functions of the heart?

Move blood through vasculature, deliver oxygen-rich blood to tissues, carry CO₂-rich blood to lungs.

What happens when the heart (pump) fails?

Fluid backs up into lungs/pleural space (pulmonary edema) or abdomen (ascites).

Common signs of cardiac disease?

Cardiomegaly, tracheal deviation, pulmonary edema, cough, exercise intolerance, collapse, poor perfusion.

What is cardiomegaly?

Enlargement of the heart.

What causes tracheal deviation on radiographs?

Enlarged heart pushing the trachea dorsally.

What is pulmonary edema?

Fluid accumulation in the lungs due to left-sided heart failure.

Why does cough occur with cardiac disease?

Enlarged heart or pulmonary edema compressing airways.

Why does exercise intolerance occur with cardiac disease?

Poor perfusion and decreased cardiac output.

Most common cause of cardiac enlargement in small breed dogs?

Mitral valve insufficiency.

What type of murmur is heard with mitral valve insufficiency?

Systolic murmur.

Why does mitral valve insufficiency cause a systolic murmur?

Regurgitation of blood back into the left atrium during systole.

Why is dental health important in mitral valve insufficiency?

Dental disease can worsen valvular disease via bacterial spread.

Symptoms of mitral valve insufficiency?

Exercise intolerance, murmur, cough.

Causes of cough in mitral valve insufficiency?

Pulmonary edema and left atrial enlargement.

How is mitral valve insufficiency diagnosed?

Radiographs and echocardiography.

Therapy for mitral valve insufficiency?

Sodium restriction, ACE inhibitors, bronchodilators, diuretics, tranquilization, oxygen.

What does left atrial enlargement indicate?

Chronic mitral valve insufficiency.

What breeds commonly develop dilated cardiomyopathy (DCM)?

Large breeds, especially Dobermans and Boxers.

Symptoms of dilated cardiomyopathy?

Similar to mitral valve insufficiency: cough, exercise intolerance, poor perfusion.

Therapy for dilated cardiomyopathy?

Similar to mitral valve insufficiency: ACE inhibitors, diuretics, positive inotropes.

What is hypertrophic cardiomyopathy (HCM)?

Thickening of the ventricular muscle, most common in cats.

What condition commonly causes secondary HCM in cats?

Hyperthyroidism.

Why does hyperthyroidism cause HCM?

Increased workload causes ventricular muscle hypertrophy.

Signs of hypertrophic cardiomyopathy?

Dyspnea, severe tachycardia, gallop S3 sound.

Signs of hyperthyroidism in cats?

Vomiting, weight loss, palpable thyroid mass.

What is congestive heart failure (CHF)?

Failure of the heart pump leading to fluid accumulation.

What fluid accumulation occurs with right-sided CHF?

Ascites (abdominal fluid).

What fluid accumulation occurs with left-sided CHF?

Pulmonary edema.

Therapy for congestive heart failure?

Diuretics, positive inotropes (e.g., pimobendan), ACE inhibitors, sodium restriction.

What is thromboembolic disease?

Formation of blood clots, often associated with HCM.

What is a saddle thrombus?

Clot at the bifurcation of the abdominal aorta.

Signs of saddle thrombus?

Acute hindlimb paresis, lack of femoral pulse, cyanotic nail beds, ischemic pain, cold limbs.

Therapy for thromboembolic disease?

Acepromazine (vasodilation), anticoagulants (heparin), aspirin (81 mg every 3 days for cats), surgery.

Prognosis for saddle thrombus?

Guarded.

What is an ECG/EKG?

Recording of electrical activity of the heart.

What does the P wave represent?

Atrial depolarization.

What does the QRS complex represent?

Ventricular depolarization.

What does the T wave represent?

Ventricular repolarization.

What is the P-Q(R) interval?

Beginning of atrial excitation to beginning of ventricular excitation.

What is the S-T interval?

Depolarization of the entire ventricle.

What is the Q-T interval?

Ventricular depolarization through repolarization.

What is the cardiac cycle?

Repeating changes in pressure and volume during one heartbeat.

What is an arrhythmia?

Abnormal conduction of the heart's electrical system.

Example of a benign arrhythmia?

Sinus arrhythmia in dogs.

Example of a lethal arrhythmia?

Ventricular fibrillation.

Therapy for arrhythmias?

Antiarrhythmics, pacemaker.

What causes heartworm disease?

Dirofilaria immitis.

Where do adult heartworms reside?

Great pulmonary vessels and right side of the heart.

Why do heartworms reside in the right side of the heart?

They enter pulmonary circulation first and obstruct pulmonary arteries.

Failure on the right side of the heart causes...

fluid accumulation in abdoment

Failure on the left side of the heart causes...

fluid accumulation in lungs (fluid edema, pleural effusion)

What is cardiomegaly

Enlarged heart visible on radiographs; often due to valve disease or cardiomyopathy

What is deviation of the trachea

The enlarged heart pushes the trachea dorsally - common with left atrial enlargement

What is pulmonary edema

Fluid in the lungs from left-sided heart failure; causes crackles and dyspnea.

Why is coughing a sign of heart disease

from pulmonary edema or compression of mainstem bronchi by an enlarged left atrium

Where do you start when evaluating cardiac size on a radiograph?

At the level of the T4 vertebra

Normal size of heart in dogs.

within a range of 8.4 to 10.5

What positioning is standard for taking heart radiographs

Right lateral radiographs

We commonly say that on a V/D radiograph right side cardiomegaly looks like a reverse ______________?

D

The vertebral heart score measures the _________________ axis and __________________ axis and compares it to the vertebrae starting at which vertebrae____________?

(long, short, 4th)