ATRIAL SEPTAL DEFECT 3RD MOST COMMON CHD

TIME RUNNING OUT FOR RAREST PRIMATE

RESCUE BID LAUNCHED TO SAVE HAINAN GIBBON FROM BECOMING FIRST APE DRIVEN TO EXTINCTION BY HUMANS

Human runs so much behind his achievement, Neither he is accountable nor has time to see what car wheel has crushed

INCIDENCE

• 56 per 100 000 livebirths• 100 per 100 000 livebirths by Echocardiograghy• 65—70% :II ASD• 50% of primum ASD and 40—50% SV ASD are seen in

female.

CAUSES/ASSOCIATION

• Familial clustering:autosomal dominant• Mutations in the cardiac transcription factor gene NKX2-5,GATA4 and TBX5 and MYH6

[14q12]• AV block: NKX2-5

• Fetal alcohol syndrome• Cigarette consumption• Antidepressants• Diabetes• Maternal age ≥35 years

SYNDROME ASSOCIATION

• Holt-Oram:60% cases have ASD• Ellis van Creveld• Noonan• Down:42% have primum and secundum ASD• Budd-Chiari• Jarcho-Levine

DEVELOPMENT

• Atrial septation is derived from septum primum, septum secundum, septum spurium and the atrioventricular canal septum

• At 28 days after gestation, septum primum (Sep 1°)—the first septum to appear in the developing atria—develops as a crescent-shaped structure. Its leading edge is covered by a layer of mesenchymal cells called mesenchymal cap. The space between the developing septum primum and the developing endocardial cushions is called foramen primum or ostium primum. Septum secundum (Sep 2°; limbus of the fossa ovalis) is a crescent-shaped muscular infolding of the atria wall that appears shortly thereafter to the right of septum primum

• At 35 days, both septum primum and septum secundum continue to develop. The openings within septum primum are called foramina secondi

• At 60 days, the atrial septum is nearly fully formed and the foramina secundi close by way of coalescing fenestrations within septum primum. The foramen ovale remains patent throughout pregnancy

CONTD……

Normal development of the atrial septum results in formation of the fossa ovalis, which includes two anatomical elements: first, muscular boundaries contributed by septum secundum; and second, the valve of the fossa ovalis, which attaches on the left atrial aspect of septum secundum—septum primum. The atrial component of the atrioventricular canal septum lies anterior and inferior to the fossa ovalis, separating it from the tricuspid and mitral valve annuli—the atrioventricular canal septum. The tissue that separates the right pulmonary veins from the superior vena cava and from the posterior and inferior aspects of the right atrial free wall is termed sinus venosus. The tissue that separates the coronary sinus from the left atrium is termed coronary sinus septum

ANATOMY

• PFO:All new born;25-30% adult• II ASD:Most common after PFO• PRIMUM ASD:A cleft in the AML and conduction abnormality • SV ASD:4—11% of all ASD;80-85% at SVC and RUPV junction• CS ASD:Raghib’ syndrome• COMMON ATRIUM: Heterotaxy syndrome • COMPLEX ASD

PATHOPHYSIOLOGY

• Left-to-right shunt• The direction and shunt : Size of the defect and by the relative atrial

pressures and compliances of the left and right ventricles• Size and the compliances of the ventricles can change over time• At birth: A transit from high PVRI and low RV compliance to a high

compliance and low resistance • Shunt works : late ventricular systole,early diastole, increasing during

atrial contraction and expiration•

• Small defects• Most defects smaller than 10 mm and shunt <1.5

• Larger defects• changes in the myocardium and in the pulmonary vasculature• Initially volume overload and later pressure overload on the right heart • Decreased left ventricular diastolic filling• Increased pulmonary-to-systemic flow ratio through the defect, and diminished systemic

output• Left ventricular systolic dysfunction develop late in patients with a large atrial septal

defect• Decrease left-to-right flow : valve or vessel stenosis and PVOD

NATURAL HISTORY

•Defect size •Clinical presentation• Exercise capacity• Pulmonary hypertension• Arrhythmia• Life expectancy

DEFECT SIZE

• Anatomical type, size, and patient-specific factors• SV and primum defects : significant shunt, do not decrease in size, and usually

need surgical closure• Secundum defects vary widely• Spontaneous closure occurs frequently in young patients with small defects• Secundum defect can increase or decrease with age• 70% of initially small (≤4 mm) defects decrease in size, 12% remain unchanged,

and 18% increase• defect size greater than 8—12 mm, only 9% decreased in size, 15% remain

unchanged, and 76% increased

PRESENTATION

• Most asymptomatic in childhood• Large also lies until adulthood• Incidental • Adult + large• Fatigue, exercise intolerance, palpitations, syncope, shortness of

breath, peripheral oedema, manifestations of thromboembolism, and cyanosis.

EXERCISE ABILITY

• Exercise intolerance is uncommon in young children• Pulmonary function is often impaired in this age• The frequency of exercise intolerance increases insidiously

with age• Exercise capacity and peak oxygen consumption are

decreased in most adults with unrepaired Secundum defect, often at 50—60% of predicted values in healthy controls

PAH

• Uncommon in children • PAH increase with age• High altitude• Eisenmenger syndrome: 5—10% • Female-to-male ratio 3

ARRYTHMIA

• Uncommon in children • Most common :atrial flutter and fibrillation• >20% have by age > 40 yrs• AV block occassional

LIFE EXPECTANCY

Campbell reported a low annualised mortality rate in the first two decades of life (0·6% and 0·7% per year, respectively), increasing to 4·5% per year in the fourth decade and 7·5% per year in the sixth decade

DIAGNOSIS

• ECHO• CT/MRI for complex anatomy or doubtful PV venous

drainage/obstruction• Cardiac catherization for PVRI in doubtful cases

CLOSURE OF ASD

• Indications• Contraindication • Timing of defect closure • Strategies :Surgery and Transcathetor closure • Clinical and haemodynamic results of defect closure

INDICATION

• American and European practice guidelines86, 87 state that an atrial septal defect can be closed if the pulmonary vascular resistance is lower than two-thirds of the systemic vascular resistance (at baseline or after pulmonary vasodilator acute challenge or targeted pretreatment course) and there is evidence of a pulmonary-to-systemic flow ratio greater than 1·5 (class IIB, level of evidence C)

CONTRAINDICATION

• American and European practice guidelines: PVR> 8 Woods units precludes closure and Eisenmenger syndrome• Pop-off valve:COPD with corpulmonale • Balloon occlusion :rise in PAP

TIMING OF SURGERY

•Ideally: 3-5 years•Usually before 25 years•Elderly: Improves morbidity and mortality

STRATEGY

• MM• DEVICE CLUSRE• SURGERY:SV ASD,PRIMUM ASD,CS TYPE,>36 MM size and

deficient rims

ADULTS WITH ATRIAL SEPTAL DEFECTS

•Unrepaired •Repaired •Pregnancy •

UNREPAIRED

• Occasionally go undiagnosed for decades• 25—30% of of GUCH• Exercise test discovers subnormal exercise capacity• Later age: fatigue, exercise intolerance, shortness of breath, palpitations,

and HF• Age,CAD,HTN and AS add to detriment• Atrial flutter and fibrillation in 21% of adults older than 40 years with a

rising frequency over time

REPAIRED

• By the age of forty• Irrespective of technique, closure of atrial septal defects after age 40 years confers morbidity and

mortality benefits compared with medical therapy alone• The risk of atrial flutter and fibrillation, remains high• In view of the risk of unmasking left ventricular diastolic dysfunction by closing an atrial

communication, test occlusion in the catheterisation laboratory is recommended before closure of the defect

• By the of age 60 years• symptomatic improvement and increase in 6 min walking distance coupled with a low procedural

risk provide the rationale for defect closure in elderly patients.

PREGNANCY

• WITHOUT PAH• Maternal complications are uncommon• Arrhythmias (4%) and transient ischaemic attack (1%).

• WITH PAH• Avoided in severe• maternal mortality was prohibitively high (28%) in women with congenital heart disease

and pulmonary hypertension, despite use of pulmonary vasodilator therapy in more than half of the patients

• Maternal deaths tended to occur shortly after delivery and were often caused by heart failure, thromboembolism, pulmonary hypertensive crisis, and sudden cardiac death.

TAKE HOME

Any kind of closure is safe and effective and when done before age 25 years is associated with normal life expectancy