Lecture 8- Aetiology of congenital heart disease Flashcards

Question

acyantoic defects

Answer 1

* **Left to right shunts** * Atrial septal defects (ASD) * Ventricular septal defect (VSD) * Patient ductus arteriosus (PDA) * **Obstructive lesions** * Aortic stenosis (hypoplasia) * Pulmonary stenosis (valve, outflow, branch) * Mitral stenosis * Coarctation of the aorta

Answer 2

* Caused by underdevelopment of the **septum primum or secundum,** resulting in a hole in the atrial septum * Allows blood in the left atrium to flow into the right atrium * Increased volume in the right atrium leads to a higher volume of blood being pumped around the pulmonary circulation * If left untreated, this will cause damage to the vasculature and fibrosis of the arteries in the lungs * Making arteries less distensible which increases resistance to blood flow and results in **pulmonary hypertension:** * Meaning right side of the heart must work against the increased AFTERLOAD * Can cause right heart enlargement (hypertrophy)à leading to heart failure * Can also cause pulmonary oedema as blood under high pressure forces fluid out of the capillaries into the lungs

Answer 3

is **not** classed as an ASD. PFO is caused by the failure of the foramen ovale to shut after birth. It is not an ASD because it is a unidirectional shunt (right atrium to left atrium) and there is no defect in the septum of the atria. In adults it generally doesn’t cause symptoms. This is because the pressure in the left ventricle is higher than that in the right, so the shunt does not allow blood to move down this gradient.

Answer 4

* If pressure in the pulmonary circulation becomes high enough due to increased resistance, the pressure in the right atrium will exceed that in the left * This will cause the flow of blood to reverse and deoxygenated blood will mix with oxygenated blood in the left atrium * Patient will become **cyanotic** due to reduce pO2 in systemic circulation- ***Eisenmenger syndrome***

Answer 5

* During development of the interventricular septum, the **membranous** portion of the septum fails to develop properly * Primary interventricular foramen remains open * Blood in the left ventricle will flow into the right ventricle * The pressure difference between the ventricles is greater than that between he atria, so more blood movement in **VSD than ASD** * By the same mechanism as ASD, VSD if left untreated will cause **pulmonary hypertension, right sided hypertrophy --\>****heart failure**

Answer 6

* Caused by failure of the endocardial cushions to develop properly * Results in a hole in the middle of the heart with one common atrioventricular valve, instead of a mitral and pulmonary valve * *Common in Down’s syndrome*

Answer 7

* Ductus arteriosus connecting the right pulmonary artery to the arch of the aorta normally shunts after the baby takes its first breath, however in PDA it remains open * This patient connection allows blood under high pressure in the aorta to flow into the pulmonary artery * This result in a higher volume of blood in the pulmonary artery, leading to a high AFTERLOAD for the right ventricle, which can eventually causes **right-sided heart failure)** * This is acyanotic heart defect because the blood reaching the systemic circulation is fully saturated with oxygen from, the lungs

Answer 8

* One or both **semilunar** valves don’t develop properly and are narrow when the baby is born * e.g. in the aortic valve – only has 2 leaflets * Results in left/right ventricular hypertrophy as the heart is having to generate more force to push blood through the stenosed valve * Hypertrophy can lead to heart failure

Answer 9

* Congenital narrowing of part of the aorta- commonly around the **ductus arteriosus** area * Upstream of the coarctation (towards the heart), blood pressure is high because it struggles to flow past the coarctation Increases risk of aneurysms of the aortic arch, and aortic root dilation which can lead to aortic valve regurgitation

Answer 10

* Downstream of the coarctation (towards the body), patients will have weak pulses and claudication (cramping in the legs due to reduced perfusion) * If narrowing is after the 3 branches of the arch of the aorta, there will be a delay between feeling the radial and femoral pulses (radio-femoral delay) * If narrowing is between the brachiocephalic trunk and the left subclavian, then there will be a delay between feeling the radial pulses in both wrists- radial-radial delay

Answer 11

*A group of heart defects that present with central cyanosis- blood in the systemic circulation is not saturated with oxygen so pO2 is low.* 1. Tetralogy of Fallot 2. Transposition of the great arteries 3. Total anomalous pulmonary venous drainage 4. Univentricular heart

Answer 12

* The tricuspid valve fails to form * Blood cannot flow from the right atrium to the right ventricle * In these babies, there is **ASD and VSD** which allows blood to flow into the pulmonary circulation * Deoxygenated blood mixes with oxygenated blood in the left side of the heart as it can only move through the ASD as the valve is fused * This mixing means that blood being pumped into the aorta and to the body will have a low pO2 resulting in central cyanosis

Answer 13

* The pulmonary valve fails to form * The only way the blood can leave the right hand side of the heart is via a septal defect * A ventricular septal effect allows deoxygenated blood to move from the right ventricle to the left ventricle where it mixes with oxygenated blood * Newborns can have a patent ductus arteriosus to allow blood into pulmonary circulation

Answer 14

* The aorticopulmonary septum forms, but does not spiral, therefore when the baby is born the aorta arises from the right ventricle, and the pulmonary trunk arises from the left ventricle * The pulmonary and systemic circulation are almost separates, with only an ASD and PDA allowing some oxygenated blood to enter the systemic circulation * This is a **neonatal emergency** and **prostaglandins** must be given to the baby quickly in order to maintain the PDA and allow some oxygenated blood into the systemic circulation until surgery can be performed

Answer 15

**Characterised by 4 defects that present together:** 1. **Pulmonary stenosis-** the pulmonary artery or valve is narrowed, so less blood can enter 2. **Overriding aorta-** aorta is large and situated right next to the VSD so most of the blood in the heart flows through it 3. **Ventricular septal defect-** allows blood from the right ventricle which cannot be pumped through the stenosed pulmonary artery/valve to move into the left ventricle and be pumped around the body via the aorta 4. **Hypertrophy of the right ventricle-** in an attempt to generate more force to pump blood through the stenosis in the pulmonary artery

Answer 16

* The ventricular septum doesn’t form, so oxygenated and deoxygenated blood mixes in the ventricle, and gets pumped into both the aorta and pulmonary trunk

Answer 17

* Mitral or aortic valve are stenosed in utero which means that less blood flows into the left ventricle- results in left ventricle being underdeveloped * ASD allows blood to flow into the right side of the heart and be pumped to the pulmonary artery and a PDA allows this blood to enter the aorta from the left pulmonary artery