Cardiac #2: Congenital Heart Defects

What is a Patent Ductus Arteriosus (PDA)?

• The ductus arteriosus is a connection between the pulmonary artery and the aorta in the fetus

• When it doesn’t close after birth, it becomes a PDA

A PDA is most common in what species? In what sex?

• Dogs

• Females

What are some Sequelae that a PDA could cause?

1. Continuous murmur

2. Bounding Femoral Pulse

3. Left congestive heart failure

What are the Hemodynamics of PDA?

1. Blood shunts from L to R via the PDA

2. Inc of blood flow to the lungs

   1. Inc of Venous blood to the LA+LV

      1. Volume overload of LV

         1. LV hypertrophy

   2. Rare CASES: Pulmonary Hypertension (Inc B.P of arteries in the lungs)

      1. Pressure overload of RV

         1. RV COncentric hypertrophy

What is Eisenmenger Syndrome? What are the C.S associated with this syndrome?

• Pressure of the RV becomes higher than the LV causing the shunt to reverse

• C.S

  • Are caused by unoxygenated blood being pumped into the LV and then around the body (bc pressure in RV>LV)

  • Cyanosis

    • Lethargy

    • Exercise intolerance

    • Collapse

    • Erythrocytosis (Higher # of RBCs)

Image is wrong, just using it to associate

What are the hemodynamics of an Atrial Septal Defect (if the defect is large enough)?

1. Blood Shunts from LA to RA

2. Inc of Blood volume in the right ventricle

3. Volume overload of RV

4. RV essentric hypertrophy

Volume overload of a ventricle causes _________ hypertrophy

Eccentric

Pressure overload of a ventricle causes ________ hypertrophy

Concentric

What is a ventricular septal defect (VSD)? What are the 2 variants?

A VSD is when the wall/septum that separates the ventricles does not form properly, resulting in communication between the LV and RV

1. High VSD

   1. Defect in the upper membranous portion of the interventricular septum

2. Low VSD

   1. Defect in the lower muscular portion of the interventricular septum

What are the Hemodynamics of a VSD?

1. Blood shunts from LV to RV (high to low pressure)

2. Inc of Blood Volume in the RV

3. Equalization of pressure between RV and LV (RV=LV)

4. LV and RV hypertrophy

What is Valvular Dysplasia?

• Abnormal shape/appearance of the valves of the heart

  • Short, thick, misshapen

  • Rolled edges

  • Absence of chordae tendineae

  • Fusions of leaflerts or chordae to the ventricular wall

  • Thick or atrophic papillary muscle

Valvular dysplasia may cause _____ or _____ of the valve

• Insufficiency

  • Valvular insufficiency is when the valve doesn’t close and blood can move “backward“

• Stenosis

  • A heart condition where a heart valve narrows, preventing it from opening fully and restricting blood flow

What are the Hemodynamics of Valvular Dysplasia?

1. Dysplastic valve is insufficient (blood can flow backwards)

2. Regurgitant blood flow during systole (contraction of the heart)

3. Volume overload of the atrium and ventricle

4. Atrial dilation and Eccentric ventricular hypertrophy

What is Pulmonic Stenosis? What are the 3 types

• Narrowing of the Pulmonary a. (carries blood from RV→Lungs for oxygenation)

1. The types are classified based off of the location of stenosis in regard to the valve

   1. Valvular

   2. Subvalvular

   3. Supravalvular

What are the hemodynamics of a Pulmonic Stenosis?

1. Stenotic valve restricts outflow

2. Pressure overload of RV

3. RV concentric Hypertrophy

4. Right Heart Failure

T/F: Pre-stenotic arterial dilation is often found in the artery, proximal to the stenosis

False, it is a Post-stenotic dilation that is often found distal to the stenosis

What is a Subaortic Stenosis (SAS)?

A narrowing of the aortic valve orifice caused by a fibromuscular membrane just below the aortic valve

T/F: A SAS is usually accompanied by a post-stenotic dilation in the aorta

True

What is the Hemodynamics of a SAS?

1. Stenotic valve restricts outflow of blood from LV→Aorta

2. Pressure overload of LV

3. LV concentric hypertrophy

   1. Arrhythmias and sudden cardiac death (if severe enough)

   2. Congestive Left Heart Failure

Along with Post-stenotic dilation, what other lesions may appear in the Aorta of a dog with SAS?

• Jet Lesions

  • The result of turbulent blood flow

What are the 4 parts of Tetralogy of Fallot?

1. Ventricular Septal Defect

2. Overriding Aorta

3. Pulmonic Stenosis

4. Right ventricular Hypertrophy

What are the Hemodynamics of the Tetralogy of Fallot?

1. Pulmonic Stenosis valve restricts valve outflow

2. pressure overload of RV

3. RV concentric hypertrophy

4. R→L shunt of blood through Ventricular Septal defect (VSD)

5. Cyanosis

   1. From un-oxygenated blood going from RV→LV→Rest of the body

What usually results in the death of animals with Tetralogy of Fallot?

Hypoxia or Hyperviscosity

Which Congenital Cardiovascular Defect(s) cause(s) L→R shunting of blood?

1. PDA

2. ASD

3. VSD

Which Congenital Cardiovascular Defect(s) cause(s) R→L shunting of blood?

Tetralogy of Fallot

Which Congenital Cardiovascular Defects cause volume overload?

Volume Overload=Eccentric Hypertrophy

1. PDA

2. ASD

3. VSD

4. Valvular Dysplaisa

Which Congenital Cardiovascular Defect(s) cause(s) pressure overload?

Aortic and Pulmonary Stenosis

Which Congenital Cardiovascular Defects cause cyanosis?

Tetralogy of Fallot