Show:
Pathology
Signalment and Physical
Diagnostics
Treatment & Prognosis
R --> L shunt
100
What is the ductus arteriosus and what is its purpose before birth?
Normal fetal connection between the aorta and pulmonary artery which shunts blood away from non-functional lungs back to systemic circulation. It allows the right heart to develop.
100
What is the most common signalment for animals that have a PDA and which breeds are most affected?
Young animals. Females are affected more than males. Breeds: Collies, Shelties, Labs, Poodles, Maltese, Spaniels, Newfoundlands, German Shepherds, Pomeranians, Keeshonds, Bichons, Yorkies
100
What abnormalities are seen on radiographs?
enlargement of the left atrium, left ventricle, aorta, and pulmonary artery
100
What are the 2 main treatment options for fixing a PDA?
Surgical ligation and Device occlusion (catheters or plugs)
100
What causes a right to left shunt?
Pulmonary pressure > systemic pressure reverses the blood flow and causes pulmonary hypertension
200
What causes the DA to not close at birth?
Inadequate amount of smooth muscle. Increased oxygen tension associated with blood flow through ductus stimulates smooth muscle vasoconstriction.
200
Is there a genetic basis to inheritance?
Yes and it has been identified in toy/mini poodles and Welsh corgis
200
What is the characteristic sign of a PDA seen on radiographs?
Aneurysmal bulge in the aorta at the level of the ductus
200
What are some complications of surgical ligation and which is the most important one?
Hemorrhage, laryngeal dysfunction, air embolization, CNS hypoxia, myocardial hypoxia, hypothermia, hypo/hypercapnea, respiratory acidosis/alkalosis
200
How is the reversal of blood flow clinically important?
Mixes non-oxygenated blood from the pulmonary artery with oxygenated blood from the aorta, causing some of the non-oxygenated blood being sent into systemic circulation
300
What causes the left sided eccentric hypertrophy?
Volume overload of the left atrium and ventricle due to excess volume overload of the pulmonary system
300
How do animals with PDAs normally present?
Asymptomatic puppies MC. May present for exercise intolerance or stunted growth Owners may report that they hear the heart "buzzing"
300
What abnormalities are seen on ECG?
Wide P waves (LA enlarged), Tall R waves (LV enlarged), normal MEA, atrial fibrillation
300
What are some complications of device occlusion?
Coil dislodgement, inaccurate coil deployment, lameness, residual flow, hemorrhage at cut down, pulmonary artery embolization, hemolysis, implant infection
300
What are some physical exam findings? Which is the hallmark finding?
Differential cyanosis, no murmur, normal-weak pulses, lethargy, syncope, dyspnea, tachypnea
400
What determines if the blood flow of the PDA is continuous?
blood pressure of systemic circulation > pulmonary circulation
400
What abnormalities are heard on thoracic auscultation?
Continuous murmur high in the left axilla (washing machine or waterfall). PMI at 3rd intercostal space but heard all over thoracic cavity. Left apical systolic murmur may be identified if mitral regurgitation is also present.
400
What abnormalities are seen on Echo?
High velocity turbulent flow and continuous flow into the pulmonary artery as blood exits the PDA; LA and LV eccentric hypertrophy, flattening of intraventricular septum
400
What is the prognosis with surgery in comparison to without surgery?
Excellent prognosis if PDA is closed by 6 months but 65% develop CHF by 1 year of age if PDA is not closed
400
What are the diagnostic findings on radiographs, ECG, and Echo?
ECG: P pulmonale, negative QRD, right axis shift of MEA. Rads: enlarged RA, RV, and pulmonary artery. Echo: enlarged RA, RV, pulmonary artery, and bubbles in the aorta.
500
Which outcome is more likely associated with a large shunt than a small shunt?
CHF is more likely because increased flow in a large shunt overwhelms the left heart and the lungs
500
What abnormalities are found on physical exam other than those found on thoracic auscultation?
bounding femoral pulses, tachypnea, crackles, wheezes, exercise intolerance, weight loss
500
What is the appearance of the cardiac silhouette on radiographs?
Lateral: tall and wide, loss of cranial waist; DV: elongated cardiac silhouette
500
What radiographic and physical exam changes are noted after surgery?
Patient should no longer have a murmur. Pulmonary vessels are WNL in 1 week. Heart should look normal on radiographs within 3 months.
500
What are the treatment options for a right to left shunt?
medical management via phlebotomy, Hydroxyurea, Pentoxyfyilline, and exercise restriction