Lecture 4.1 - Congenital Heart Diseases PDF

Congenital heart defects: ◦Present from birth ◦Detection has been possible for ~30 years - prenatal ultrasound ‣ Can see the 'moderator band' which allows you to establish the right ventricle. ‣ Allows you to see if the heart is forming at the right angle...

Congenital heart defects: ◦Present from birth ◦Detection has been possible for ~30 years - prenatal ultrasound ‣ Can see the 'moderator band' which allows you to establish the right ventricle. ‣ Allows you to see if the heart is forming at the right angle and in the right location ◦Screened at 20 weeks gestation ◦Most defects which permits months of intrauterine life = live offspring at full term ◦Can be classified as cyanotic and acyanotic Acyanotic congenital heart defects: ◦Left to right shunt - direction of blood flow, since left side is at a higher pressure ◦Oxygenated blood pushed to deoxygenated blood ◦Does not cause cyanosis ◦Increased pulmonary blood flow ‣ Atrial septal defect ‣ Ventricular septal defect ‣ Patent ductus arteriosus ◦Common causes: ‣ Down syndrome (trisomy 21) ‣ Foetal alcohol syndrome ‣ Intrauterine infections (e.g. rubella) ‣ Maternal diabetes ‣ Advanced maternal age Atrial septal defect: ◦Primum ASD (septum primum doesn't reach septum intermedium) ◦Secundum ASD (septum secundum) doesn't completely block ostium secundum - more common ◦Sinus venosus defects ◦Most common congenital heart defects found in the adult ◦Left to right shunt - describes the flow of blood from the left to the right side of the heart ◦Excess blood in the right atrium and right ventricle ◦Right ventricular dilation: ‣ Parasternal heave (behind the sternum)  ‣ Reduced CO (as you lose oxygenated blood from the right side of the heart) ‣ Sympathetic activation: raised HR, RR and fatigue ◦Increased pulmonary artery hypertension (PAH) - can cause blood to leak out of pulmonary arteries and excess fluid flows into the lungs (pulmonary oedema): ‣ Dyspnoea (shortness of breath as there is blood in the lungs) ‣ Recurrent chest infections (as there is excess fluid in the chest cavity) ◦Increased venous congestion -> raised JVP (jugular vein pressure), swollen ankles - due to oedema, hepatomegaly (excess blood in the liver, so liver becomes enlarged) ‣ Right ventricular afterload increases, so blood backs up into the right atria and then the veins ◦Systolic ejection murmur (upper left sternal border), fixed splitting of S2 (atrial-septal defect - excess blood flowing into the right ventricles, so pulmonary valve closes slower than mitral valve), diastolic rumble (left lower sternal border in the tricuspid area) ◦Surgical repair if volume is significant ◦Different from patent foramen ovale (not an atrial septal defect) - here blood flow is from RA to LA as the foramen ovale doesn't close. ‣ Patients could present with stroke due to increased risks of blood clotting (paradoxical clot formation) Ventricular septal defect: So ◦Membranous VSD (membranous portion does not form) - more common ◦Muscular VSD (muscular portion does not form ◦Most common congenital cardiac malformation ◦Left to right shunt, increased pulmonary artery hypertension (PAH) - as there is excess blood in pulmonary artery ◦Large defects may lead to dilation of left atrium and left ventricle (displaced apex beat) ‣ Ventricular preload increases ◦Holosystolic (or pansystolic) murmur left sternal angle (pulmonary valve area), loud S2 - as there is excess blood pushed into pulmonary arteries, diastolic rumble (apical-in the apex) ‣ Excess blood flowing through the mitral valve, which can be felt at the left sternal border ◦Small VSDs create larger murmurs and vice versa - a smaller VSD means blood flows at higher velocity Patent ductus arteriosus: ◦Some of the blood from the aorta crosses the ductus arteriosus and flows into the pulmonary artery (as the aorta is at higher pressure in comparison to the pulmonary arteries) ◦Continuous 'machinery' murmur best heard below the left clavicle in the first interspace or over the first rib ‣ You can hear this in diastole and systole ◦Increased pulmonary artery pressure - as there is excess blood in the pulmonary arteries ◦Left heart dilation (displaced apex beat) and volume overload (from pulmonary veins) ◦PDA: Prostaglandins keep the ducts open as its level doesn't go down. So, drugs to inhibit PGE can be given Coarctation of the aorta: ◦Narrowing of the aorta at, or just distal to, the insertion of the ductus arteriosus ◦Severe obstruction of blood flow in the descending thoracic aorta ◦Encourages the formation of a collateral arterial circulation involving the intercostal arteries (rib notching) - can be seen on chest X-ray ◦Significant coarctation leads to hypertension in the upper limbs and weak, delayed (radio-femoral delay) pulses in the legs.  ◦Differential cyanosis (cyanosis of lower limbs only) Congenital aortic valve stenosis: ◦Thickening of aortic valve leaflets ◦Bicuspid aortic leaflet structure ◦LV hypertrophy due to increased LV afterload - left ventricle cannot pump properly, so the body tries to compensate this ◦Children: Tachycardia, tachypnoea, poor feeding ◦Adults: Fatigue, exertional dyspnoea, angina, syncope ◦Crescendo-decrescendo murmur ◦Balloon valvuloplasty (balloon at the end of a catheter, and placed into a distal artery) can be used to repair stenosis Congenital pulmonic valve stenosis: ◦Impairment of RV outflow (therefore increased afterload)→ Increased RV pressure→ RV dilation and hypertrophy ◦Increased RV pressure ◦RV dilation and hypertrophy (parasternal heave) ◦Right sided heart failure ◦Dyspnoea on exertion, exercise intolerance, pedal oedema ◦Systolic ejection murmur at the upper left sternal border ◦Splitting of the S2 heart sound due to delayed closure of the pulmonary valve Cyanotic congenital heart defects - need immediate treatment: ◦Left to right shunts can progress to Eisenmenger syndrome (acyanotic to cyanotic condition) ◦If the septal defect is big, can progress to Eisenmenger syndrome ◦Left to right shunts lead to increased pulmonary arterial hypertension (PAH) ◦Right sided pressure eventually rises above left side→ shunt reversal→ blood flowing from right to left→ cyanosis ◦Mixed oxygenated and deoxygenated blood is now pumped into the systemic circulation ◦Low oxygen levels in blood ‣ Cyanosis ‣ Clubbing of fingers ‣ Polycythemia - RBC volume increases Eisenmenger in PDA (patent ductus arteriosus): ◦Large PDA can develop Eisenmenger syndrome ◦Cyanosis/clubbing of feet and lower extremities  Tetralogy of fallot (cyanotic): ◦Pulmonary obstruction ◦Right ventricular hypertrophy ◦Overriding aorta ◦Ventricular septal defect ◦'PROVe it' - all problems happening at the same time ◦With severe pulmonary outflow obstruction blood is shunted through VSD from right to left ◦Thus the patient is centrally cyanosed (cyanosis of digits, mucous membranes and lips) ◦Identified in-utero during ultrasound scanning ◦Surgical closure of the VSD and pulmonary valve replacements are needed The overall survival of those who have had operative repair is excellent Transposition of great arteries (TGA): ◦Not compatible with life - has to be treated as soon as possible ◦Occurs due to incomplete spiralling of great arteries in embryogenesis sees ◦Aorta connected to RA and pulmonary artery connected to LA ◦Incompatible with life since deoxygenated blood from the systemic venous return passes into the right heart and then, via the aorta, back to the systemic circulation ◦Babies with transposition are born cyanosed and rely on an ASD, VSD or PDA allowing oxygenated and deoxygenated blood to be mixed. ◦In those without an adequate shunt a balloon atrial septostomy (BAS) is performed in utero: a balloon is deployed to dilate the foramen ovale and is used to maintain saturations at 50–80% until a definitive procedure can be performed. ◦Arterial switch should be done as soon as possible after birth ◦Survival rate is high