SHA24/004001

Wail alkashkari Consultant adult congenital and structural heart disease intervention King Faisal Heart Center King abdulaziz Medical City National Guard, Jeddah

Definition

Atrial septal defect (ASD) is a direct communication between the cavities of the atrial chambers that permits shunting of blood

Anatomy

Classification

Secundum

Primum

Sinus venosus superior

Sinus venosus inferior

Unroofed coronary sinus defect

Secundum ASD (70%) It is defects within the oval fossa, in spite of the fact that the oval fossa is the primum septum

Superior SVD (5-10%) It is a deficiency of infolding of the atrial wall in the environs of the SVC. It is found within the mouth of the SVC, which has a biatrial connection, overriding the rim of the oval fossa so as to produce what is effectively an extracardiac but interatrial communication.

It is associated in 80–90% with partial anomalous return of the RUPV, which empties into the upper part of the RA or directly into the SVC

Inferior SVD (2%) It is localized in the mouth of the IVC and is associated with partial anomalous return of the RLPV. The Eustachian fold may constitute a false rim of the defect and detour blood from the IVC to the LA. This type of defect may thus be an undetected cause of cyanosis in adulthood

Defect of the coronary sinus (unroofed coronary sinus) It is very rare defect.

The defect is in the wall separating the coronary sinus from the left atrium.

It is usually associated with persistence of the LSVC that emptying into the left atrium or into the coronary sinus

ASD of the ostium primum type constitutes an incomplete form of atrioventricular septal defect It accounts for 15–20% of all defects at atrial level.

Patent foramen ovale is not considered a defect; it occurs in 25–30% of the population at large.

Large interatrial communications may represent a confluence of one type of defect with another.

Genetics and Epidemiology

ASD accounting for about 9–11% of all CHD in childhood.

ASD accounts for 22–30% of all CHD in series of adult patients.

It is the most frequent CHD in adults (except bicuspid aortic valve).

Down syndrome Primum and Secundum ASD DiGeorge syndrome and Ellis-van Creveld syndrome Primum ASD Secundum defects may be associated with skeletal abnormalities of the forearm and hand (Holt–Oram syndrome) which result from mutations of TBX5, a member of the brachyury family of genes.

The familial forms of secundum ASD have been associated with GATA4 &NKX2.5 mutations. In these forms, prolonged AV conduction times are common.

Pathophysiology

The ASD allows shunt blood flow between the atria.

The magnitude & direction of BF depends on the ASD size & the compliance (stiffness) of the ventricles.

The pressure in the respective atria is dependent on the compliance of the respective ventricles The Lďƒ R shunt is due to higher compliance of the RV (less stiff) than LV.

Lďƒ R shunt RV dilation RV failure

Ventricular arrhythmias

TR

RA dilatation Atrial arrhythmias (AF, Aflut,AT) Clot formation CVA, Distal embolization PE

Increase Pul flow Pulmonary A dilation (PR) Hyperkinetic pulmonary hypertension PA remodeling (thickening)

Established Pul Hypertension

Factors to be considered in adult Even a small defect <10 mm can be associated with significant shunt in conditions that decrease LV compliance (>stiff) eg IHD, HPT (systolic and diastolic dysfunction) or left sided valve disease.

RV failure (decrease compliance) and severe TR especially with exercise can decrease the Lď&#x192; R shunt.

Diastolic function of the LV is adversely affected by the volume-overloaded RV (interventricular interaction) LVEDP SHUNT In childhood RV dilation can led to LV hypoplasia.

There are other factors in adult contribute to high PA pressure: LV dysfunction LVEDP LAP  PCWP Chronic lung disease Adult at higher risk of PE (DVT) and in situ thrombi formation

Underlying genetic factors can modify the phenotype and predispose the patient to the development of severe pulmonary vascular disease in the presence of a shunt at the atrial level.

The high pulmonary blood flow can trigger the development of pulmonary vascular disease.

Clinical Presentation

ASD in adult usually asymptomatic.

Many young patients with even a large ASD practiced sports experiencing no problems at all.

Symptoms set are insidiously, most often after the age of 40 or 50.

Symptoms may include the following: - Reduced exercise tolerance, tiredness.

- Exertional dyspnea.

- Palpitations (due to SVT eg AF) or syncope for sick sinus syndrome - Atypical chest pain (right ventricular ischemia).

- Frequent respiratory tract infections.

- Symp of right HF or left HF. - Paradoxical embolism from peripheral venous or pelvic vein thrombosis, atrial arrhythmias, unfiltered intravenous infusion, or indwelling venous catheters.

Endocarditis (rare) Pulmonary hypertension ď&#x192; Eisenmenger syndrome

The problem most of theses symptoms can be attributed to different diseases that commonly occur in elderly.

In women, the clinical status may deteriorate during pregnancy or after delivery.

Natural History and Long-Term Sequelae

Most patients who have undergone early closure of a defect remain well with an excellent outlook and a normal survival (when repair is undertaken before 25 years of age).

Older age at repair is a risk factor for premature late death, which becomes progressively more powerful with increasing age at operation

Survival

Arrhythmia

Exercise Capacity

Cardiac Remodeling Remodeling of the RA and the RV can occur within 24hr from the ASD closure up to one year.

The magnitude of RA remodeling is inversely related to patient age at the time of closure, as demonstrated in one study that reported persistent RA dilation in up to 64% of patients who underwent late ASD closure

Pulmonary HPT Pulmonary vascular disease may occur in up to 5% to 10% of patients with untreated ASDs, predominantly in females

Clinical Examination

Cyanosisâ&#x20AC;&#x201D;uncommon and more likely with a large defect or virtually common atrium, an inferior sinus venosus defect, a large coronary sinus defect, pulmonary vascular disease, or associated pulmonary stenosis, right ventricular dysfunction, or Ebstein anomaly.

RV heave, but the LV impulse is usually normal.

Wide and fixed split of the second heart sound (delayed pulmonary artery valve closure); a loud pulmonary component reflects severe pulmonary hypertension.

Ejection systolic murmur heard best at the left sternal border (increased blood flow through the pulmonary artery orifice) (relative pulmonary stenosis); sometimes, a pulmonary ejection click can be heard.

Diastolic murmur at the lower right sternal border due to increased blood flow through the tricuspid orifice (relative tricuspid stenosis).

Examination should focus also on the status of the left heart pathology eg MR.

CXR Mild to moderate cardiomegaly.

Increased pulmonary vascular markings in patients with large left-to-right shunts

Ostium secundum ASD. Mild right-axis deviation, voltage evidence of RVH

Ostium primum ASD. First-degree AV block, left-axis deviation, voltage evidence of RVH

Sinus venosus ASD. Inverted inferior P waves, right-axis deviation

Eisenmenger ASD. Marked right-axis deviation, right atrial overload, right ventricular hypertrophy with strain pattern

TTE To see the defect: Defect in the atrial septum, best seen in the apical four chamber and sub-costal long-axis views.

However it is common to see ‘echo fallout’ in the region of the interatrial septum misdiagnosis

Improvements in 2D echo with harmonic imaging have improve the diagnostic accuracy.

Some key points regarding the use of these imaging modalities: - Bubble contrast echocardiography with provocation has led to the accurate diagnosis of interatrial communications - The left arm is chosen so as not to miss a persistent left SVC with anomalous drainage to the left atrium

A positive test sees the rapid transit of bubbles from the right to the left heart within three to five cardiac cycles.

The amount of bubbles seen is related to the size of the defect. Late transit (>5 cardiac cycles) of bubbles is associated with intrapulmonary shunting

Some maneuvers are performed to transiently increase right atrial pressure and to provoke shunting through a potential interatrial communication.

Typical maneuvers include a sharp nasal sniff, a cough, or the relaxation phase of the Valsalva maneuver.

TTE can demonstrate the hemodynamic consequences of the Lď&#x192; R shunt.

Dilation of the RA, RV, and PA. Tricuspid valve annular dilation with associated TR. Estimation of the RVSP and in the absence of PV stenosis an estimate of the SPAP

thrombus

PA

Associated lesions of the MV (MVP, MS, MR), TV (Ebsteinâ&#x20AC;&#x2122;s anomaly), PV (PR,PS).

Exclude intracardiac thrombus

TEE It is mandatory prior to consideration of device closure or surgery.

Demonstration of all four pulmonary veins draining to the LA. Measure the margins of the atrial septum for suitability for device closure.

Exclude other ASD

PV

LA

PV LA

PV

LA SCV RA

Sup

Ant

Post nf

MRI It is an additional means of demonstrating the ASD and its location.

To assess pulmonary venous connections if doubts remain after other imaging modalities have been used, and it can also be used to estimate Qp/Qs

CTA It is an additional means of demonstrating the ASD and its location.

To assess pulmonary venous connections, if doubts remain after other imaging modalities have been used.

To assess the existence of CAD in patients >40 years of age when surgical repair is contemplated.

Cardiac catheterization To determine PAP & PVR. To assess pulmonary vascular reactivity if pulmonary hypertension is present To delineate anomalous pulmonary venous connection(s) For selective coronary angiography, in patients at high risk for CAD or in patients >40 years when surgical repair is contemplated

Epidemiology in Saudi Arabia Dr Abbag reported the pattern of CHD in the all children referred to the Pediatric Cardiology clinic in Asir central hospital with suspected CHD (July 1994 to June 1996), total of 335 patient.

The prevalence of ASD was 10.4%

Ann Saudi Med 1998;18(5):393-395.

Alnajjar et al, found that ASD is the second most common CHD in madena maternity and children hospital, 9%.

Saudi Medical Journal 2009; Vol. 30 (9): 1186-1191

Mansour Alqurashi et al, conducted study covering the major 5 regions in Saudi Arabia between 2004-2005.

Alabdulgader et al found in epidemiological studies done in 4 regions of Saudi Arabia (August 1988-February 2000) and 2604 individuals with congenital heart disease were evaluated, atrial septal defect (18.1%).

East Mediterr Health J. 2006 ;12 Suppl 2 :S157-67

Al-ama et al conducted study to find out what is the pattern of CHD in down syndrome patients (112) in KAAU hospital jeddah 2007-2011.

ASD in 38/92 (41.3%).

Saudi Med J 2012; Vol. 33