Acyanotic congenital heart defects

Acyanotic congenital heart defects Jamie Mathew, PGY-1July 27, 2015

Overview Review of fetal circulation Individual lesions L to R shunts, vascular anomalies Epidemiology, embryology, pathophysiology, presentation, diagnosis, treatmentDiscussion, questions Fetal circulation

3 shunts; Ductus venosusForamen ovale Ductus arteriosus Placental umbilical vein Joins with portal vein to supply the liver Less than 1/3: passes through ductus venosus, shunt number 1 away from liver, join directly with IVC IVC RA bypass lungs via foramen ovale (shunt number 2) LA LV aorta internal iliac aa umbilical aa Most blood enters RV pulmonary circulation passes from PA to descending aorta via ductus arteriosus (shunt number 3) - RV receives more CO than LV, so it is more dominant. Identical pressures in both Fetal heart cannot increase SV. The only way to increase CO is to increase HR. that is why decrease in HR can be so dangerous 3Removal of low resistance placenta Increased systemic resistance Closure of ductus venosus Lung expansion pulmonary vascular resistance, pulmonary blood flow, pulmonary artery pressure pulmonary venous return LAP LAP > RAP foramen ovale closes arterial SpO2 closure of PDAChanges in circulation after birth-oxygen acts as vd on pulmonary vasculatuew 4Left to right shunts ASDVSDECDAtrial septal defect: Epidemiology 2nd most common congenital heart defect 0.67 2.1 / 1000 live births 30-50% children with heart defects have an ASDSecundum most commonTwice as many females Four typesOstium primum ASDOstium secundum ASDSinus venosus defectCoronary sinus septal defect -secundum 90%, sinus venosum and primum each 3-4%6

Atrial septal defect: EmbryologyRight pic: Embryologic formation of foramen ovale. A: septum primum begins to grow from the mid-portion of the common atrium roof towards the endocardial cushions and the ostium primum (OP) remains between them. B: septum primum fusion with endocardial cushions. C: a second wall begins to form, septum secundum, to the right of the septum primum; a second orifice, ostium secundum (OS), forms in the upper portion of the septum primum; the septum secundum finally covers the OS. D: lateral view of the interatrial wall with foramen ovale. E: frontal view of the interatrial wall.

-first 23 days: atrial chamber is common -third week: atrial septation begins. Septum primum forms from endocardial cushion, grows toward AV canal area. This becomes superior and ingeruir cushionsss. The cushions fuse and bend toward the atria as the septum primum goes downward. The small resulting passageway between the atria is the ostium primum. -ostium primum eventually closes, but before that there is a central opening in it that forms and it is called the ostium secundum. To the right of the ostium primum the septum secondulk forms; its edge is called the foramen ovale. -birth: high LAP + increased pulmonary blood flow septum primum pushed against septum secundum closure of ostium secundum7ASD: ClassificationOstium primum ASDEndocardial cushions do not close the ostium primumAssociated with cleft in anterior mitral leaflet, trisomy 21 Ostium secundom ASD Most common and least harmful ASDDefect in fossa ovalisExcessive resorption of septum primum underdevelopment of ostium secundumMay be associated with atrial septum aneurysm

-Because endocardial cushions also form the mitral and tricuspid valves, ostium primum defects are virtually always associated with a cleft in the anterior mitral valve leaflet-Ostium primum ASDs may occur in isolation but most commonly present with a cleft in the anterior leaflet of the mitral valve. This is sometimes termed a partial AV canal defect or a partial AV septal defect. Can lead to mitral regurg. 8ASD: Classification Sinus venosus defect Near SVC or IVCPartial anomalous pulmonary venous connection of right upper or lower pulmonary vein Coronary sinus septal defect Least common Associated with L SVC-also seen in secumdum -most common form partial anomalous

-roof of coronary sinus mising blood shunted from LA into coronary sinus RA 9ASD: Presentation Magnitude of shunt determined by: Size of defect Compliance of ventricles Usually no sx Poor weight gain, DOE, frequent URIsSystolic murmur from increased flow across pulmonary valve (LUSB)Diastolic murmur from increased flow through tricuspid valve (LLSB)Wide split and fixed S2 from RBBB-RV more compliant than LV L to R shunt -magnitude of shunt reflected in degree of cardiac enlargement -shunt itself does not cause a murmur-diastolic murmur if it is a large shunt-may not have any auscultation findings in ingant -RBBB delays RV depol and contract pulm valve closes late-fixed: large shunt abolish resp-related fluctuations in VR. Large venous return to RA fixed S210ASD: Echo

11ASD: EKG

-ECG from a patient with a partial atrioventricular septal defect. The PR interval is mildly prolonged. Left axis deviation with Q waves in leads I and aVL are present, consistent with a counterclockwise loop in the frontal plane (from AV node being displaced conduction is altered). Right atrial enlargement and an rsR' pattern in the right chest leads also are noted.-Diagnosis of a primum ASD or a partial AV canal defect often can be made based on physical examination findings and the ECG alone. The ECG abnormalities (seen in the image below) are predominantly caused by abnormalities of the conduction system. Specifically, the AV node is displaced posteriorly and inferiorly, and atrial and/or AV nodal conduction often is delayed.-Displacement of the AV node results in a counterclockwise loop in the frontal plane in 95% of cases. The QRS axis is outside the normal range for age, demonstrating either a left or far left axis, and Q waves are present in leads I and aVL.-Delayed conduction through the atria or through the AV node may lead to prolongation of the PR interval (ie, a first degree AV block).-Abnormalities in the right precordial leads are similar to those in secundum-type ASDs. The QRS pattern typically is either an rSr' or an rsR' resulting from dilation and hypertrophy of the right ventricular outflow tract caused by volume overload of the right heart.-Right atrial enlargement is often detected, demonstrated by a peaked P wave measuring more than 2.5 mm (standard 10 mV/mm). It is best seen in leads II, III, V1, and V3R.-With significant mitral regurgitation, left atrial enlargement may be present, demonstrated by a P wave duration of more than 0.08 sec and/or terminal and deep inversion of the P wave in lead V1 or V3R.

12ASD: CXR

-cardiomegaly, large RA and RV-prominent PA, increased pulm vasc markings -obliteration of retrosternal space - Superimposed mitral regurgitation results in left atrial and13ASD: Natural history ASD 80% ASD >8mm: spontaneous closure rareRisk of CHF, pulmonary HTN in adulthood Most children no sx. Rare risk of infant-onset CHFNo significant risk of infective endocarditis Paradoxical embolism rare Arrhythmias rare ASD: Treatment Depends on comorbiditiesCardiac catheterization Surgical repair Pulmonary to systemic flow ratio > 1.5:1RA and RV enlargement 1/3 experience postpericardiotomy syndrome -CHF, mitral valve problems -to be asurgery candidate, need evidence of significant shunt -surgery very safe, 1 year: shunt Qp>Q2 > 2:1 Contraindications: R to L shunt, pulmonary vascular obstructive disease Mortality: 2-5% after 6 months Higher: