Congenital heart defects, arrhythmias & congestive heart failure

What are congenital heart defects?

Heart defects present at birth

Coarctation of the aorta

Narrowing of a segment of the aorta = decreased flow of oxygenated blood

• forces the L ventricle to pump harder, increasing BP

Patent ductus arteriosus

Failure of the ductus arteriosus to close

• results in aortic blood flowing into the pulmonary trunk

• this increases the pressure in the pulmonary trunk = overworking of both ventricles

What are the 4 congenital defects in tetralogy of Fallot?

• interventricular septal defect

• aorta emerging from both ventricles

• stenosed pulmonary valve

• enlarges R ventricle

What is the result of the 4 congenital defects in tetralogy of Fallot?

Decreased blood flow to the lungs and mixing of blood across heart chambers = impaired O2 delivery to tissues = cyanosis

• can be surgically repaired

What is an arrhythmia?

Abnormal heart rhythm

Symptoms of arrhythmias

• chest pain

• bradycardia

• fibrillations

What is AV block?

Conduction between atria and ventricles is blocked at the AVN

What does 1st degree AV block present as on an ECG?

Prolonged PQ interval

Atrial fibrillation

Where contraction of the stria is asynchronous = atria stop pumping altogether

• the atria don’t contract fully - just flutter = blood pooling/ stagnation in atria

• this increases the likelihood of stroke (due to blood clots)

What do ECGs look like for atrial fibrillation?

No clearly defined P wave

• irregular spaced QRS complexes (and R-R intervals)

What is congestive heart failure?

Loss of pumping efficiency by the heart

What can cause CHF?

• CAD

• Congenital defects

• Long-term hypertension

• MIs

• valve disorders

What effect does the loss of pumping efficiency have on the heart?

• more blood remains in the ventricles at the end of each cycle = gradually the end-diastolic volume (preload) increases

• initially the increased preload promotes increased contractility BUT in the LT as preload increases further the heart is overstretched and contraction decreases in force

What does L sided heart failure result in?

Blood backing up onto the lungs = pulmonary oedema

• if the fluid accumulates it can cause suffocation

What does R sides heart failure result in?

Fluid backs up in systemic veins and and over time kidneys increase blood volume

• peripheral oedema = more noticeable in the feet and ankles