ATRIAL SEPTAL DEFECT

Presenter: Dr. Archana Shrestha Yadav

Resident Phase A

OBJECTIVES

IntroductionEmbroyology Incidence and Genetic AssociationsPathophysiologyTypes of ASDNatural History Evaluation and Management

INTRODUCTION

ASD is an acyanotic CHD characterized by defect in the interatrial septum causing a left to right flow between the atria

Severity depends on : - size of defect - size of shunt - associated anomaliesResulting in spectrum from : asymptomatic to right sided overload, PAH , even atrial arrhythmias

EMBROYOLGY OF HEART

Septum formation in primitive atrium

INCIDENCEASD constitutes 8-10% of congenital heart

defects in children.Incidence = 56 per 100,000 live birthsRecent estimates are much higher (100 per

100,000 live births), likely due to increased recognition in the era of common use of echocardiography

female: male ratio for secundum ASD = 3:1For sinus venosus ASD= 1:1

ETIOLOGYActual etiology of this congenital defect is

unknown.

Some factors may play role as there are some evidences of being association with ASD.

Factors include: - Genetic factor - Environmental factor including antenatal

use of teratogenic drugs, congenital infection

GENETICSThe genetic basis of ASD is not completely

understood.In the majority of cases this is a sporadic

lesion, yet some homeobox gene defects have been found to explain some of the well known familial cases of ASDs, such as NKX2-chromosome-5, which has an autosomal dominant inheritence and AV conduction defect.

Other genetic syndromes with skeletal abnormalities HOLT-ORAM Syndrome, which is accused by mutations in the transcription factor TBX5, essential in development of both the heart and upper limbs.

ASD can be part of many other syndromes like DOWN syndrome and Noonan syndrome

HEMODYNAMICS

Desaturated blood enters the right atrium from the vena cava at a volume of 3 L/min/m2 and mixes with an additional 3 L of fully saturated blood shunting left to right across the ASD

Results in :increase in oxygen saturation

in the right atrium. Six liters of blood flows

through the tricuspid valve and causes a mid-diastolic flow rumble.

Oxygen saturation may be slightly higher in the right ventricle because of

incomplete mixing at the atrial level.

The full 6 L flows across the right ventricular outflow tract and causes a systolic ejection flow murmur.

Six liters returns to the left atrium, with 3 L shunting left to right across the defect and 3 L crossing the mitral valve to be ejected by the left ventricle into the ascending aorta.

PATHOPHYSIOLOGY

TYPES

Ostium Secundum (75-85%)Ostium Primum (10-15%)Sinus Venosus (5-10%)Coronary Sinus septal defect (1%)

Ostium Secundum

• Most common type.• Defect in the region of

fossa ovalis.• Single or Multiple.• May be associated with

partial anomalous venous return most commonly of the right upper pulmonary vein.

Ostium Primum

• Situated in the lower portion of the artrial septum and overlies the mitral and tricuspid valve.

• Often associated with clefts in the anterior mitral and septal tricuspid valve leaflets and small VSDs.

Sinus Venosus

• Least common type.• Situated in the upper

part of atrial septum in close relation to the entry of the Superior venacava.

• Abnormal fusion between embryologic sinus venosus and atrium.

ACCORDING TO SIZE:In younger children – In older children Small defect: <3 mm Small defect: <6 mm Moderate defect: Moderate defect: 3 – 8 mm 6 – 12mm Large defect: >8 mm Large defect: >12 mm

ASSOCIATIONS

Associated malformations are nearly 30% of Cases. Like: Secundum ASD ● Pulmonic stenosis ● Mitral valve prolapse ● Partial anomalous pulmonary venous connection Primum ASD ● Cleft mitral valve ● Discrete subaortic stenosis Sinus Venosus septal defect ● Partial anomalous pulmonary venous returnCoronary Sinus septal defect ● Partial and total anomalous pulmonary venous return ● Persistent left superior vena cava

SYMPTOMS AND SIGNSVary with the size of defect.

Small defect: Asymptomatic and is usually diagnosed during a routine health check up.

Large defect: Symptomatic and patients usually present with Failure to thrive. Easy fatigability. Increased perspiration Recurrent Pulmonary infections. Platypnea Orthodeoxia

On examination

General examination Appearance: Usually normal Heart rate: Normal Respiratory rate: Normal Weight and height: may be less than 10th centile.

Precordium

Inspection: Slight prominence of precordium

Palpation: Apex beat may be shifted to left P2 may be palpable Left parasternal heave may be

present

Auscultation:

S1 is normal S2 is widely splitted and

fixedEjection systolic

murmur ,medium pitched, soft, grade 1-3/6 & best heard at left 2nd & 3rd ICS

A diastolic flow rumble across the tricuspid valve region.

INVESTIGATIONS

Routine tests :(CBC, septic screening, s.electrolyte, s. creatinine, blood grouping, coagulation profile, etc) should be done before management.

Diagnostic Investigations includes- -X-ray -Ecg -Echocardiography -Sometimes cardiac catheterization

Xray Findings

CardiomegalyRA enlargement RV enlargementFull pulmonary conusIncreased pulmonary

vascular markingsPlethoric lung fields

ECG

Enlarged ‘p’ wave indicating Right atrial hypertrophy

rsR’ seen and tall R waveIndicating RBBB and RVH

Also note that the aVF is predominantly upwards as compared to Lead I indicating Right Axis Deviation

LAD with rSR’ in V1 is suggestive of Ostium primum defect

Associated lesions- -Right atrial and RV enlargement with diastolic flattening and paradoxical IVS motion are evidence of RV volume overload and a significant left- to-right shunt, - mitral valve prolapse, -cleft mitral valve, -anomalous pulmonary veins. Contrast echocardiography with intravenous

agitated saline may be used to confirm the presence of a shunt if color Doppler are not conclusive.

RA LA

RV

Echocardiogram

Primary diagnostic imaging modality for ASD.

Provides: - exact localization of ASD - size of ASD - measurement of septal rims - Confirmation of the shunt - Abnormal motion of ventricular septum. - Associated lesions can be identified

Cardiac catheterization

Patients with the classic features of a hemodynamically significant ASD on physical examination and chest radiography, in whom echocardiographic identification of an isolated secundum ASD is made, need not undergo diagnostic catheterization before repair, with the

Exception: an older patient, in whom pulmonary vascular resistance may be a concern.

NATURAL HISTORY

In patients with an ASD <3 mm in size diagnosed before 3 months of age, spontaneous closure occurs in 100% of patients at 1½ years of age.

Spontaneous closure occurs more than 80% in patients with defects between 3-8 mm before 1½ years of age.

An ASD with a diameter > 8 mm rarely closes spontaneously.

Most children with an ASD remain active and asymptomatic. Rarely, congestive heart failure (CHF) can develop in infancy.

If untreated, pulmonary hypertension and subsequent CCF may develop during or after third decade, and reversal of shunt may occur (rare), it may be progressive with pregnancy

With or without surgery, atrial arrhythmias (flutter or fibrillation) may occur in adults.

Infective endocarditis does not occur in patients with isolated ASDs.

Cerebrovascular accident, resulting from paradoxical embolization through an ASD, is a rare complication.

Mitral stenosis may occur as a result of rheumatic fever in a case of ASD (Lutembacher syndrome).

COMPLICATIONS OF ASD

Right sided heart failureFrequent pulmonary infectionsFlow-related PAHPulmonary vascular obstructive diseaseParadoxical embolismTricuspid and mitral insufficiencyAtrial arrhythmias—atrial flutter, atrial fibrillation,

and Sick Sinus Syndrome.

MANAGEMENT

Patients with small shunts and normal RV size are generally asymptomatic and require no therapy but need longtime follow up for spontaneous closure.

Moderate to large shunt and/or symptomatic ASD should be managed with following strategies:

- Medical therapy

- Interventional therapy

- Surgical therapy

Medical management

Aim to reduce volume overload and to strengthen functions of heart muscles.

Symptomatic children : Diuretics: -These agents relieve ventricular overload, peripheral and pulmonary congestion Digoxin:

-Helps to strengthen the heart muscle, enabling it to pump more efficiently

Afterload reducers:

- Enalapril

- Captopril

Exercise restriction is no necessary

Prophylaxis for infective endocarditis is not

indicatedAtrial arrythmias : Appropriate Antiarrhythmic

drugs.Atrial fibrillation : Antiarrhythmic drugs +

anticoagulants.

Irreversible PAH :dobutamine, calcium channel blockers (high dose), diuretics, prostacycline, sildenafil or oxygen therapy.

Treatment of Other complications, like-

pulmonary infections, thrombo- embolic events

or heart failure should also be treated

accordingly.

Interventional therapy

Closure of ASD :In patients with small secundum ASDs and

minimal left-to-right shunts without right ventricular enlargement, closure is not required

Indications of ASD closure-All symptomatic patients Asymptomatic patients with-

• Qp : Qs ratio of at least 2 : 1 • Right ventricular enlargement

Time of closure- usually after the 1st yr and before entry into school

Interventional therapy

Indication:i. Echocardiographic evidence of ostium secundum ASDii. Clinical evidence of RV volume load ( i.e. 1.5:1 degree

of left to right shunt or RV enlargement ) iii. ASD diameter less than 36 mmiv. Presence of sufficient rim of tissue( at least 5 mm) v. Patient with fenestrated Fontan lateral tunnel if

temporary balloon occlusion is tolerated

Contraindication:Sinus venosus, coronary sinus or primum ASDExtensive congenital cardiac anomaly.Known sepsis within one month prior to implantation or

any untreated systemic infection prior to device placement.

Bleeding disorder, untreated ulcer or any other contraindications to aspirin therapy.

Demonstrated intracardiac thrombi on echo. Any patient whose size or condition would cause to be a

poor candidate for cardiac catheterization.

Different ASD closure devices:

Clamshell(TM) device

Buttoned device

Angel wings(TM) device

Atrial septal defect occluder system device

Advantages of device closure-

It is safe and cost-effective than

surgery

Successful implantation rates

more than 96%,

Fewer complications: Major<1%,

Shortened hospitalization

Avoidance of pain and residual

thoracotomy scars

Reduced need for blood

products.

Disadvantages of device closure-

Higher rate of small residual leak

Complications of Device Closure:

Device misalignment/embolization

Device erosion of atrial wall or aorta

Device impingement on adjacent structures AV valve, Coronary sinus, SVC, Pulmonary veins, Aorta

Infection including endocarditisThromboembolic ComplicationAllergic reactionValvular regurgitationResidual shunt

Follow– Up After Device Closure:

Clinical - assessment of symptoms of arrhythmia, chest

pain, or embolic events.

Echocardiography surveillance - device position, residual

shunting, and complications such as thrombus

formation or pericardial effusion.

Frequency of follow-up echocardiography - usually at

24 hours, 1 month, 6 months, and 1 year and at

regular intervals thereafter.

Surgical management

Surgical management

Surgical closure has been the “gold standard” form of treatment of ASD

Surgeons need proper training and expertise in performing operations.

The surgical approach can be by right thoracotomy or sternotomy, and more limited incisions are feasible with either approach.

Procedure- Simple suture or patch closure

Timing-Surgery is usually delayed

until the patient is 2 to 4 years of age because the possibility of spontaneous closure exists.

In infancy- If CCF not respond to medical management

Indication: ASD with RA and RV enlargement with / without

symptoms.

ASD minimum diameter > 10 mm on echocardiography

A sinus venosus, coronary sinus or primum ASD

Chronic atrial arrythmia with ASD (concomitant Maze

procedure)

Contraindication: Patients with severe irreversible PAH & reverse shunt

SPO2 < 90%

Advantages of Surgery-

Can be performed in any type of ASD

Associated anatomical abnormality can be corrected concurrently.

Excellent late outcome.

Disadvantages of Surgery-

CostlyNeeds expertise handsProlong Hospital staypain and residual

thoracotomy scars

Complications:

● Pericardial effusion / constriction

● Residual shunt

● RV systolic and diastolic dysfunction

● Pulmonary artery pressure

● Mitral regurgitation

● Pulmonary vein stenosis or caval vein stenosis (sinus venosus defects)

● Arrhythmia

● Tricuspid regurgitation

Follow – Up After Surgical Closure:Early postoperative follow-up:

-Symptoms of undue fever, fatigue, vomiting, chest pain, or abdominal pain

( may represent post pericardiotomy syndrome with tamponade and needs immediate evaluation with echocardiography.)

Annual clinical F/U: (if following conditions persist or develop)

- PAH.

- Atrial arrhythmias.

- RV or LV dysfunction.

- Coexisting valvular or other cardiac lesion

PROGNOSIS:Patients generally survive up to adulthood without

surgical or percutaneous intervention mainly with small to moderate size ASD and many patients live to advanced age.

The results after surgical or device closure in children with moderate to large shunts are excellent.

Mortality is less than 2% after surgical closure of uncomplicated ASD

Mortality and morbidity increase with pulmonary vascular disease

TAKE –HOME MESSAGES

Atrial septal defects are relatively common CHD

Early symptoms are usually rare except very large deffect.

Any kind of closure is safe and effective and associated with improved life expectancy

A comprehensive treatment plan should include input from the primary care provider, the Paediatric Cardiologist and the Paediatric Cardiovascular surgeon.

THANK YOU