Lecture 18 9/23/24 Flashcards
What are the characteristics of subvalvular aortic stenosis?
-results from a subvalvular fibrous ring
-valvular and supravalvular stenosis are uncommon in the dog
What is the pathophysiology of subvalvular aortic stenosis?
-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
What are the classifications of SAS based on pressure gradient?
mild: < 40 mmHg
moderate: 40-80 mmHg
severe: > 80 mmHg
What is the typical signalment of SAS?
-large breed dogs
-uncommon in puppies/younger animals
What are the physical findings associated with SAS?
-systolic murmur over the left heart base
-weak/hypokinetic arterial pulse
What are the characteristics of SAS diagnosis?
-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
What are the treatment options for severe SAS?
-balloon dilation
-potential for cutting balloon/high pressure balloon
-beta-blockade; ineffective in decreasing mortality
What are the history characteristics of SAS?
-broad spectrum of severity
-heart failure and pulmonary edema are uncommon
-severe cases create risk for sudden cardiac death
What is a ventricular septal defect?
a hole or defect in the interventricular septum
What is the pathophysiology of ventricular septal defect?
-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
What is the typical signalment/history of VSD?
-relatively common in cats
-predisposed in bloodhounds, english bulldogs, and shiba inus
-common congenital malformations in horses and cattle
What are the physical findings associated with VSD?
-isolated VSD results in systolic murmur
-restrictive defects associated with right apical thrill
What are the treatment options for large VSD shunts and other complex anomalies?
-surgery under bypass
-transcatheter occlusion
-medical therapy
What does VSD prognosis depend on?
-defect size
-presence of concurrent lesions
What are the characteristics of atrial septal defects?
-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
What are the consequences of tricuspid or mitral valve dysplasia?
regurgitation and/or stenosis
What are the characteristics of AV valve dysplasia?
-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
What are the characteristics of cyanotic heart disease?
-defects that result in venous admixture/right-to-left shunts
-uncommon defect
What are the requisites for cyanotic heart disease?
-communication between pulmonary and systemic circulations
-right atrial hypertension or pulmonary artery/right ventricular hypertension
What determines the direction of the shunt with small/restrictive VSD?
pressure difference
What determines the direction of the shunt with large VSD?
-PVR
-left-to-right if PVR < SVR
-right-to-left if PVR > SVR
What are the clinical signs associated with cyanotic heart disease?
-exercise intolerance
-complications of polycythemia/too many red blood cells
What is Eisenmenger’s physiology?
elevated pulmonary blood flow can result in vascular disease, rise in PVR, and shunt reversal
What are the characteristics of right-to-left PDA?
-shunt reversal occurs early in life
-typically do not have murmurs
-marked hind-limb exercise intolerance
-therapeutic phlebotomy is palliative
What are the characteristics of Tetralogy of Fallot?
-PS/VSD/right ventricular hypertrophy/aortic override occur together
-definitive repair under bypass, phlebotomy, and beta blockade are potential treatments
