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Acyanotic Congenital Heart Disease

Atrial Septal Defect
Cause is benign. ASD represents ~ 10% of all CHD

Eitiology
· Failure of septal growth
· Excessive reabsorption of tissue

Natural hx :
-make ~ 7% of all cases of cong HD
-female:male=2:1
-pulmo vasc resistance is lower than N
-heart failure is rare
-in adulthood significant number of individual who had HF/A.flutter/pulmo vasc D èhad surgery / catheter closure (wh has low risk)wh was performed after 5y.o

3 Types of ASD:
i. Primum
-defect located near the endocardial cushion
-may B part of a complete AV canal defect
-occur in lowermost part of the atrial septum & extend to mitral & tricuspid valve
-usually accomp with AV valve defects
-cleft in ant leaflet of mitral valve
-septal leaflet in tricuspid valve
-in severe case: primum ASD + deformities of mitral & tricuspid valve + VSD = commom AV canal

ii. Secundum
-most common ASD
-hole in region of foramen ovale
-can B isolated or accomp with other cardiac lesion
-hemodynamically significant lesions are accomp with RA & RV dilatation, RV hypertrophy, dilatation of pulmo artery àsignify effect of chronically ↑ volume load on R-side of heart
-s/t accomp with pulmo HPT
-most likely to present in middle to late adulthood, either with ↑ fatigue or with atrial aryhthmias

iii. Sinus venosus
-least common
-assoc with anomalous pulmo venous return to RA or SVC
-located hi in atrial septum

Amount of shunting depends on :
-size of defect
-relative compliance of R+L ventricle

CM:
-infants with ASD rarely present with CHF
-chlidren mostly have no CV symptom
-some pt remain asymp, may B dev easy fatigability as older children or adults
-cyanosis not dev unless pulmo HPT dev

PE:
-periph pulse: normal & equal
-RV impulse at left lower sternal border
-no thrills usually
- S2 at pulmonic area is wide & oftenly fixed
-soft systolic ejection murmur at upper /2nd L sternal border (at RV outflow tract)àdt ↑ flow in pulmonic valve
-No murmur from flow across ASD dt low velocity

Imaging studies:
v ECG: pure RV enlargement
-↑ blood flow via RA, RV, pulmo arteries & lungs
-RV hypertrophy
v CXR:
-cardiomegaly
-RA enlargement
-prominent pulmo artery (↑ pulmo artery vascularity)

Treatment:
1) Secundum ASD:
-surgical / catheterization lab closure (with interventional device)
-perform electively in pt btwn ages 1 & 3 y.o
-mortality rate is <1%
-when closure is performed by age 3y.o, late complication of RV dysF(x) & significant dysrhythmias are avoided
-early : always indicated for infant with CHF or pulmo HPT

2) Non secundum ASD
-prophylactic antibiotic vs subacute bact endocarditis
-significant shunt is still present at 3y.o àclosure is required

3) Primum + sinus venosus à surgical closure

Complication:
a. Pulmo HPT
b. Right to left shunt
c. Infective endocarditis


Patent Ductus Arteriosus:

AD allows blood to flow from pulmo artery to dec part of aorta drg fetal life. Failure of normal closure of DA results in PDA
↓ of pulmo vasc resistance after birth results in L to R shunting of blood & ↑ pulmo blood flow to occur
PDA represent ~ 5%-10% of all CHD

Natural hx of PDA:
-is poorly defined
-3 major deviations:
1. At the same pulmo artery P, the risk of dev of pulmo vasc D > in PDA than in VSD
-in PDA blood go to pulmo artery immediately
2. At same age, risk to egt infective endocarditis > in PDA than VSD coz jet stream induces initial damage
3. The incidence of spont. closure in PDA is v. small. So, dt simple surgery wh is low risk, all single congenital PDA with L to R shunting shud be closed
-some using double umbrella device, some using surgical ligation
Now, w/out surgery, put device intraartery & dt jet stream, the device opened (just like an umbrella)

CM:
Symptoms dpnds on amount of extra blood flow to lung wh dpnds on:
- Size of PDA
- Pulmo vasc resistance

Ø Widened pulse pressure

Ø Continuous machine like murmurà run off of blood from aorta into pulmo circ during diastole (dt P pulmo artery is < P aorta)
-best heard at L intraclavicular area
-palpable thrill
-radiate along pulmo arteries(usually radiate fairly well in ant lung field but poor over post lung field) & well heard over the L back
-begin shortly after S1, rises to a peak at S2, & passes to S2 in diastole where it becomes a decrescendo murmur & fades before S1

Ø Mid-diastolic murmur (often heard at apex) à ↑flow across mitral valve
Ø If the caliber of PDA is wide, > transmission of systemic pressure in pulmo artery occurs. The wider & shorter PDA, the higher RV pressure & the > PV hypertrophy, as well as LV hypertrophy

Imaging Studies:
1) ECG & Echo:
-LV hypertrophy + LA enlargement
-RV hypertrophy (if pulmo HPT is present)
2) CXR:
-full pulmo artery silhouette
-↑pulmo vascularity

Treatment:
· Spontaneous closure is uncommon in full-term infants
· Moderate to large PDA à diuretics + digoxin
· Most PDA can be closed in catheterization lab à coil embolization or PDA closure device (when W =5kg)
· Ico pulmo HPT Ö, operation by age of 1y.o to prevent dev of progressive pulmo vasc D

Ventrical Septal defect
Delaying closure in vent septum btwn 5-6 wks of embryonated life
Variable in size, can B located in any part of vent septum, single or multiple lesion

Location:
1) Subpulmonary (membranous)
2) Perimembranous (most common)
3) AV canal type (give severe defect)
4) Muscular (usually small, may close spont)

Anatomy: 4 components of vent septum:
§ Muscular
§ Membranous (below aortic valve)
§ Supracristal /subarterial(comprises conotruncal tissues)
§ Inlet or posterior (comprises endocardial cushion tissues)

History of VSD
-most common cardiac lesion, making ~30% of congenital HD
-catheterization:- to access
-VSD small enuff to have normal P pulmo artery : P syst flow = 2:1 à no need for surgery if closure x (↑ pulmo vasc resistance xoccur
-small % of baby had HF + admin to hosp à almost always had HF by 2m.o (ico large L-R shunt)

-VSD occur when any of these components fail to dev normally
-most common CH defect à 25% of all CHD
-female = male
-The amount of flow crossing VSD (give significant clinical value) dpnds on:
§ Size of defects
§ Pulmo vasc resistance
§ Variation of both above factors with age
-even large defects are asymptomatic at birth dt hi pulmo vasc resistance. Pulmo vasc resistance usually ↓ over 1st 6-8 wks of life
-at 6-8 wks of life, symptoms of VSD may dev
-often detected at 2-6 wks of life
-murmur at 1st day of life esp ico small or moderate defect

CM:

Small VSD:
Often asympt
Clinical course is benign
Normal pulmo artery pressure

Moderate to Large VSD:

§ Pulmo overcirc
§ CHF presenting as fatigue, diaphoresis with feedings + poor growth
§ Pansystolic murmur + thrill à best heard at lower L sternal border (1-2 months, dt vent F 2˚ to large L-R shunting
§ P2 not accentuated
§ Initial:-
-tachyP with ↑ resp effort
-excessive sweating dt ↑ sympathetic tone
-fatigue when feeding (hx of feeding is imp)

Large VSD:

-Mid-diastolic murmur at apex dt ↑ flow across mitral valve
-Acyanotic
-Easy fatigability
-CHF in infants only
-hyperactive heart, bivent enlargement
-pansystolic murmur, max at lower L sterna border
P2 accentuated
-Diastolic flow murmur at apex

Rx

Small VSD:
§ Close spont
§ Prophylactic antibiotic needed to prevent subacute bact endocarditis (if defect xclose)
§ No catheterization

Moderate to large VSD:

§ Initial Rx:
-diuretics
-Digoxin
§ Continued poor growth / pulmo HPT:
-close defect by surgery
-close by devices placed at cardiac catheterization

Large VSD:
Surgery & med management of HF
Ico VSD: resp infection, underweight, growth retardation are common

PE:
-L chest deformity
- ↑ precordial activity
- change in ausc sx

Imaging Studies:
1) ECG:
-LA + LV enlargement
-LV hypertrophy

2) CXR:
-cardiomegaly
-↑pulmo artery silhoutte

3) Echo:
-↑ pulmo blood flow

-editted & revised version. Source: lect notes, Robbin's Pathology, Lange Pediatric, Nelson Pediatric.

Enjoy!