Lecture 18 9/23/24

Question 1

What are the characteristics of subvalvular aortic stenosis?

Answer 1

-results from a subvalvular fibrous ring
-valvular and supravalvular stenosis are uncommon in the dog

Question 2

What is the pathophysiology of subvalvular aortic stenosis?

Answer 2

-LV must generate abnormally high systolic pressures to maintain normal systemic pressures and flow
-pressure gradient develops across the obstruction
-imposes a pressure overload on the LV

Question 3

What are the classifications of SAS based on pressure gradient?

Answer 3

mild: < 40 mmHg
moderate: 40-80 mmHg
severe: > 80 mmHg

Question 4

What is the typical signalment of SAS?

Answer 4

-large breed dogs
-uncommon in puppies/younger animals

Question 5

What are the physical findings associated with SAS?

Answer 5

-systolic murmur over the left heart base
-weak/hypokinetic arterial pulse

Question 6

What are the characteristics of SAS diagnosis?

Answer 6

-important to diagnose all forms, even mild ones, because of genetic implications
-auscultation is accepted screening method
-doppler echo. indicated when a murmur is detected

Question 7

What are the treatment options for severe SAS?

Answer 7

-balloon dilation
-potential for cutting balloon/high pressure balloon
-beta-blockade; ineffective in decreasing mortality

Question 8

What are the history characteristics of SAS?

Answer 8

-broad spectrum of severity
-heart failure and pulmonary edema are uncommon
-severe cases create risk for sudden cardiac death

Question 9

What is a ventricular septal defect?

Answer 9

a hole or defect in the interventricular septum

Question 10

What is the pathophysiology of ventricular septal defect?

Answer 10

-isolated VSD results in a left-to-right shunt and imposes a volume load on LA and LV
-clinical importance depends on size of defect and presence of other defects

Question 11

What is the typical signalment/history of VSD?

Answer 11

-relatively common in cats
-predisposed in bloodhounds, english bulldogs, and shiba inus
-common congenital malformations in horses and cattle

Question 12

What are the physical findings associated with VSD?

Answer 12

-isolated VSD results in systolic murmur
-restrictive defects associated with right apical thrill

Question 13

What are the treatment options for large VSD shunts and other complex anomalies?

Answer 13

-surgery under bypass
-transcatheter occlusion
-medical therapy

Question 14

What does VSD prognosis depend on?

Answer 14

-defect size
-presence of concurrent lesions

Question 15

What are the characteristics of atrial septal defects?

Answer 15

-left-to-right ASD imposes a volume load on the RA and RV
-any resulting murmur is a “flow murmur” that results from a “relative PS”
-uncommon defect that can be repaired with catheterization or surgery

Question 16

What are the consequences of tricuspid or mitral valve dysplasia?

Answer 16

regurgitation and/or stenosis

Question 17

What are the characteristics of AV valve dysplasia?

Answer 17

-tricuspid/right AV valve dysplasia is relatively common in labrador retrievers
-severity is quite variable
-regurg. as a result of dysplasia requires bypass for correction

Question 18

What are the characteristics of cyanotic heart disease?

Answer 18

-defects that result in venous admixture/right-to-left shunts
-uncommon defect

Question 19

What are the requisites for cyanotic heart disease?

Answer 19

-communication between pulmonary and systemic circulations
-right atrial hypertension or pulmonary artery/right ventricular hypertension

Question 20

What determines the direction of the shunt with small/restrictive VSD?

Answer 20

pressure difference

Question 21

What determines the direction of the shunt with large VSD?

Answer 21

-PVR
-left-to-right if PVR < SVR
-right-to-left if PVR > SVR

Question 22

What are the clinical signs associated with cyanotic heart disease?

Answer 22

-exercise intolerance
-complications of polycythemia/too many red blood cells

Question 23

What is Eisenmenger’s physiology?

Answer 23

elevated pulmonary blood flow can result in vascular disease, rise in PVR, and shunt reversal

Question 24

What are the characteristics of right-to-left PDA?

Answer 24

-shunt reversal occurs early in life
-typically do not have murmurs
-marked hind-limb exercise intolerance
-therapeutic phlebotomy is palliative

Question 25

What are the characteristics of Tetralogy of Fallot?

Answer 25

-PS/VSD/right ventricular hypertrophy/aortic override occur together
-definitive repair under bypass, phlebotomy, and beta blockade are potential treatments