Atrial septal defect

An atrial septal defect (ASD) is a pathological opening with a shunt between both atria. The persistent Foramen ovale, which has no hemodynamic significance, must be distinguished from this. However, the transitions are sometimes but fluid (Lapp 2010).

The ASD shows anatomically 4 different appearances:

• Ostium secundum defect, also called septum secundum defect or ASD II: This defect is the result of an inhibition of the development of the septum secundum and is located in the middle section of the atrial septum, near the foramen ovale. (pinger 2019). The defect must be diagnostically delimited from a persistent foramen ovale (Kasper 2015). In about 25% of these defects there is also a partial pulmonary vein malfunction (Pinger 2019).
• Ostium primum defect, also called septum primum defect or ASD I: This defect is caused by a disturbed development of the septum primum. The defect is located near the AV valves, which are usually malformed or insufficient (Kasper 2015). The defect is almost always connected to a cleft in the mitral valve (Pinger 2019) and is more common in children with trisomy 21 (Kasper 2015).
• Sinus-venosus defect, also known as high atrial septal defect: This defect is located in the posterior upper part of the atrial septum, mostly at the junction of the superior cava (Kasper 2015), then called superior type (Herold 2019), less frequently at the inferior cava (< 1%), which corresponds to the inferior type (Herold 2019). It is combined up to 90 % with a partial pulmonary vein malfunction (Pinger 2019).
• Coronary sinus defect: The defect is located in the area of the coronary sinus (Pinger 2019).

The atrial septal defect accounts for approximately 25% of congenital vitae in adults (Herold 2019). It occurs predominantly in combination with other viti (Pinger 2019).

Women are affected twice as often as men (Herold 2019), with up to 75% of ASD II occurring in the female sex, while the other forms show no gender preference (Pinger 2019).

ASD I occurs in about 15% of cases, ASD II in about 80%, sinus venosus defects in about 5% (Pinger 2019), the rest are rare defects (Herold 2019).

ASD is one of the congenital heart vities.

There is also a familial ASD with autosomal dominant inheritance. However, this is extremely rare and is called Holt-Oram syndrome. In this case, both an ASD and a ventricular septal defect can exist along with other anomalies (radius aplasia, complete right bundle branch block or AV block, etc.).

(Schmaltz 2008)

The clinical picture varies greatly, depending on the severity of the defect.

In children, often only:

• Growth disorders
• recurrent infections

(Kasper 2015)

The actual manifestation of the disease usually begins at an early age. Then it can come to:

• reduced physical resilience
• Apnea, initially only under stress
• Palpitations
• common respiratory infections
• in the further course of the disease, signs of right heart failure may appear (edema of the dependent body parts, jugular venous congestion, liver enlargement, in the late stage also ascites and pleural effusion possible [Herold 2018])

Patients with small or medium-sized defects (up to 10 mm) often remain asymptomatic into adulthood.

(pinger 2019)

Chest X-ray

In the X-ray thorax, typical signs of congenital vitia with left-right shunt are found:

• increased lung perfusion
• increased pulmonary vascular drawing (also called pulmonary plethora [Stierle 2014]; this weakens with the development of pulmonary vascular disease [Kasper 2015])
• prominent pulmonary arch

[Herold 2019)

In addition, radiographs may show:

• enlarged atrium on the right
• enlarged ventricle on the right (may become marginal on the left [Stierle 2014])
• narrowed aorta

[Herold 2019)

• dilated cardiac waist (Pinger 2019)

Echocardiography

Echocardiography should be performed both transthoracically and transesophageally, as some changes are better visualized on transesophageal examination (Herold 2019).

From subcostal, the septal- secundum defect is best visualized, and from apical, the primum defect (Pinger 2019).

The following changes may exist:

• a contour defect is found in the atrial septum
• dilatation of the right atrium, right ventricle and truncus pulmonalis
• the interventricular septum shows paradoxical movement (caused by volume loading of the right ventricle)
• detection of the shunt direction

in the Doppler method:

- estimation of right ventricular and pulmonary arterial pressure

in contrast echo

(Herold 2019)

• Evidence of shunt':
  • low contrast crossover from the right atrium to the left atrium
  • any washout phenomenon present gives evidence of a left-right shunt

(Pinger 2019)

Cardiac MRI

This method of investigation is not required for a simple ASD II unless the patient is poorly palpable.

However, if there is a suspicion of other abnormalities, cardio- MRI should be performed to detect, differentiate, or exclude them. (Pinger 2019)

Sometimes the right ventricle can only be assessed to a limited extent by echocardiography due to its anterior position in the thorax. In this case, cardiac MRI is also indicated (Kasper 2015). Likewise for exact shunt quantification (Qp/Qs [Stierle 2014]) and postoperative follow-up (Kasper 2015).

Cardiac catheterization

Cardiac catheterization can provide concrete information for oxymetric shunt quantification, pulmonary resistance can be calculated accurately, and defect size (balloon- sizing) can be determined (Herold 2019).

Indications for investigation are:

• Non-invasive measures have proven inadequate for assessment.
• V. a. pulmonary hypertension
• V. a. associated abnormalities
• V. a. a CHD

Provided an uncomplicated ASD is present or non-invasive measures have already accurately assessed the defect, cardiac catheterization is not necessary.

(Pinger 2019)

Natural history

The natural course in an ASD can differ widely. It is possible to have:

- Spontaneous occlusion

Spontaneous occlusion may occur in a small ASD (< 5 mm) in 80% of cases in the first 4 years of life.

• Risk of endocarditis

However, in an isolated ASD, the risk of endocarditis is low.

• Atrial arrhythmias may occur (atrial flutter or fibrillation).

• Increase in pulmonary arteriolar resistance (this risk is only slight in isolated ASD and then occurs preferably only in older age).

• Symptomatology in natural history:

With a small left-right shunt, patients may be asymptomatic until the 5th decade of life. Only thereafter do symptoms appear. By the 6th decade of life, almost all patients are symptomatic.

(Herold 2019)

• Life expectancy with natural history:

Overall life expectancy is reduced, but not as much as other vitias. The average life expectancy without therapy is approximately 40 years. In ASD I or complete AV canal defect, the prognosis is very poor if untreated even in infancy. The lethality in the 1st year of life is about 50%.

(Stierle 2014)

In contrast, patients with small vitia have a very good prognosis (male patients > 18 years have a median survival of 80 years [Pinger 2019]).

Overall mortality in ASD is up to 6.3% in the first 4 decades of life and between 6.3% to 9.4% after the 4th decade of life (Apitz 1998)

• Causes of death may include:
  • cerebral embolism (in atrial fibrillation)
  • Pulmonary embolism
  • paradoxical embolism (passage of a thrombus across the ASD)
  • right heart failure (in later years)
  • Brain abscess
  • Endocarditis (in associated mitral valve lesions; in isolated ASD, the risk is only slight)

(Herold 2019)

Inspection / Palpation

• mostly a gracile physique is found
• the skin color is pale
• there are lifting pulsations in the 3rd ICR left, in the right ventricular outflow tract

In the case of an already existing right-left shunt, the following symptoms are also present

• Cyanosis
• drumstick finger (Kasper 2015)

Auscultation

• in the 2nd ICR left, the 2nd heart sound is wide and fixed split auscultable (typical sign of ASD; however, this is not always auscultable; it results from the right bundle branch block and the increased right ventricular stroke volume, which leads to a delayed closure of the pulmonary valve
• in the 2nd ICR on the left, a systolic interval murmur is also heard (caused by relative pulmonary stenosis due to increased blood flow)
• in the 4th ICR on the left and along the left sternal border (Kasper 2015), an early diastolic interval murmur can be auscultated (this is caused by relative tricuspid valve stenosis)

In patients with pre-existing pulmonary hypertension, there may also be:

• in the 2nd ICR on the left an early systolic pulmonary ejection click
• a systolic interval murmur
• a tympanic 2nd heart sound
• early diastolic decrescendo murmur (due to relative pulmonary valve regurgitation, also known as Graham- Steell murmur.

Once a right-to-left shunt is in place, the auscultation sounds change:

• the pulmonary and tricuspid sounds decrease in intensity
• there is an accentuation of the pulmonary part of the 2nd heart sound and of the systolic expulsion sound
• both parts of the 2nd heart sound may coincide
• a diastolic murmur of pulmonary valve regurgitation may occur

(Kasper 2015)

ECG

The following changes may be present in the ECG:

• Right-sided type ( typical in an ASD II [Stierle 2014]).
• Steep type
• overexcited left type (typical in an ASD I; may also occur in associated mitral valve prolapse)
• ectopic atrial rhythm (especially in patients with a sinus venosus defect [Kasper 2015])
• Atrial arrhythmias
• P- dextroatrial ( P in II and III is peak positive with > 0.2 mV and in V1 , V2 the positive portion of the P- prong is peak positive and higher than 0.15 mV)
• 1st degreeAV block (occurs preferentially in patients with a sinus venosus defect [Kasper 2015])
• incomplete or complete right bundle branch block
• right ventricular hypertrophy (Sokolow- Lyon index: RV1 + SV 5 / 6 > 1.05 mV)

[Herold 2019)

• Idiopathic dilatation of the pulmonary artery. Here we find:

- a systolic-pulmonary expulsion sound

- Dilatation of the pulmonary trunk

- central pulmonary arteries are prominent

Differentiation from ASD possible by:

- during auscultation a normal division of the 2nd heart tone is found

- ECG is unremarkable

- No pulmonary plethora detectable in the chest X-ray

- no ASD is detectable in the echo; there are no signs of cardiac stress

- in case of doubt, a right heart catheter examination should be performed

• Functional heart murmur:

- is usually quieter

- the intensity decreases both in sitting position and during the Valsalva manoeuvre

• Abnormalities of the thoracic skeleton:

- in pectus excavatum and flat back, there is often a systolic expulsion sound and an incomplete right thigh block

Differentiation possible with:

- during auscultation a normal division of the 2nd heart tone is found

- There is no pulmonary plethora in the chest X-ray

- the echo shows no ASD

• Bicuspid aortic valve:

- this often causes a systolic expulsion sound

For further distinction, the following should be made:

- ECG, X-ray, chest and echo

• Pulmonary valve stenosis:

Here you can find

- a wide cleft of the 2nd heartbeat

- Signs of stress on the right ventricle

A delimitation is possible by:

- during auscultation the 2nd heartbeat shows a non-fixed cleavage

- there's no pulmonary plethora in the chest X-ray.

- the echo shows no ASD

- if doubts remain, a right heart catheter is recommended

• Mitral valve defect:

A differentiation is possible by:

- during auscultation the 2nd heartbeat shows a non-fixed cleavage

- there is no pulmonary plethora in the chest X-ray

- no right bundle branch block in the ECG

- the echo shows no ASD

If both ASD and mitral valve defects are present, a right heart catheter examination is recommended for further diagnosis.

• Lutembacher syndrome:

- The Lutembacher syndrome is a very rare malformation. It can be distinguished from ASD by echocardiography and Doppler examination.

• Persistent Foramen ovale (PFO):

- is often found by chance during right heart catheterization. The PFO represents a standard variant, it is not ASD in the true sense of the word. The prevalence is 30%, although the data in the literature vary widely (Herold 2019). It can only be distinguished from ASD on the basis of saturation and pressure criteria. Sometimes, however, the transitions are fluid.

• Partial pulmonary vein malfunction:

- this defect is mostly combined with ASD. A reliable differentiation is not possible with non-invasive methods. In this case a right heart catheter examination should always be performed.

(Stierle 2014)

Asymptomatic patients who are not restricted in their physical activity can be treated conservatively with

• a small shunt of Qp: Qs < 1.5: 1
• a small shunt and also greatly increased pulmonary vascular resistance (PVR: SVR > 0.7: 1).

Regular follow-ups are necessary. Echocardiography should be performed every 2 - 3 years. If atrial fibrillation occurs, cardioversion can be performed.

(pinger 2019)

In general, it can be said that symptomatic patients - regardless of age - always benefit in terms of morbidity (physical strain, dyspnoea, right heart failure) from the closure of ASD (Herold 2019).

The indication for surgical treatment is given:

• in all symptomatic children and young adults
• in echocardiography there is evidence of right heart enlargement
• when the blood flow in the pulmonary circulation is in relation to the blood flow in the systemic circulation (Qp / Qs) ≥ 1.5 to 2.0: 1
• Patients with paradoxical embolism after exclusion of other causes
• u. Possibly for women before a planned pregnancy

(Herald 2019)

The indication classes for surgical or interventional therapy according to ESC 2010 are:

• Indication class I:

Patients, regardless of symptoms, who have a significant shunt with signs of right ventricular volume overload and pulmonary vascular resistance (PVR) < 5 Wood units

• Indication class IIa:

Patients with paradoxical embolisms in whom other causes of embolism have been excluded

• Indication class IIb:

Patients with a relevant shunt (Qp / Qs > 1.5) and a pulmonary vascular resistance (PVR) of > 5 Wood units, if

- pulmonary vascular resistance (PVR) is less than 2/3 of the system resistance (SVR)

or

- pulmonary vascular resistance (PVR) is less than 2/3 of the arterial pressure

(ping 2019)

The objective of surgical treatment is the prophylaxis of irreversible cardiac damage caused by chronic volume stress (Herold 2019)

Contraindications for surgical treatment are given if:

• pulmonary vascular resistance (PVR) or pulmonary arterial pressure (PAP) exceeds 2/3 of the system resistance or pressure AND the ratio of Qp: Qs is < 1.5 OR vasoreactivity no longer exists
• there is pulmonary hypertension with a pulmonary artery resistance of > 10 WE x m² or the pulmonary artery resistance after administration of a vasodilator is > 7 WE x m²
• in the case of left ventricular dysfunction - both systolic and diastolic - if a pulmonary congestion develops in the catheter laboratory in the event of testoclosure via a left-atrial pressure increase

(Herald 2019)

In surgical treatment, we differentiate between interventional catheter occlusion and surgical therapy (Herold 2019).

1. interventional catheter occlusion:

Today, a total of about 80% of patients are treated with an interventional catheter occlusion (Pinger 2019). These are mainly patients with an ASD II (septum secundum defect [Schmaltz 2008]).

Different closure systems have been available for years (e.g. Angel Wings, CardioSeal Starflex, Amplatzer- Septal- Occluder etc.).

Indication:

Defects with a size of < 38 mm - 40 mm and a marginal margin of at least 5 mm

(ping 2019)

The success rate is over 90%.

Complications occur at about 1.4 %.

A residual shunt remains in about 5 % to 10 % of cases.

The mortality rate is 0 %.

Long-term experience is based on an average of 78 months.

(pinger 2019)

Postoperatively, patients should receive an antiplatelet aggregation inhibitor (e.g. ASS) and endocarditis prophylaxis for 6 months (Herold 2019).

Dosage recommendation for endocarditis prophylaxis:

• Amoxicillin or ampicillin 2 g p. o.
• if oral administration is not possible, ampicillin or cefalexin 2 g i.v. is recommended
• in case of ampicillin or penicillin allergy, clindamycin 600 mg should be given orally or i.v. - Clindamycin 600 mg i.v.

(Herald 2018)

2. surgical therapy:

Surgical therapy is carried out in the case of ASD I (often also clefts have to be repaired [Kasper 2015]), sinus-venosus defects and coronary sinus defects.

An ASD II is usually only treated surgically if an interventional treatment is not possible.

If a significant tricuspid valve insufficiency is present, surgery is also required for valve reconstruction.

(pinger 2019)

Time of the operation:

In case of an uncomplicated ASD II, the surgical therapy should be performed before the patient starts school, approx. in the 3rd - 5th year of life. In older patients, the surgical measure is recommended as an elective procedure after diagnosis.

(Herold 2019)

Technical execution:

The ASD is closed by a direct seam or by a patch closure.

(Herald 2019)

Operational lethality:

The operative lethality of uncomplicated ASD is < 1% in the first two decades (Herold 2019). After the age of 60 it increases to > 6 % (Stierle 2014).

Eisenmenger syndrome

In patients who already have Eisenmenger's syndrome, surgery alone is contraindicated for defect closure (Stierle 2014). Instead, a lung transplantation plus surgical ASD closure or a heart-lung transplantation are required.

(Herold 2019)

Patients with untreated, hemodynamically effective ASD have a life expectancy of approximately 40 - 50 years (Barmeyer 2010).

The mortality rate is 50% until the age of 36, after the age of 60 90% (Pinger 2019).

Pulmonary hypertension develops before the age of 20 in about 4 % of cases, between the age of 20 and 40 in 18 % and after the age of 40 in 40 %.

If the surgical correction of the defect does not take place until adulthood, the number of patients with normal ECG and normal x-ray is less than if the correction took place before the age of 6.

Also with regard to resilience, better results are found if the surgical correction took place before the age of 6. In the case of an operation in childhood, 93.3 % can reach the maximum stress level with ergometry, whereas this figure is only 81.2 % for patients undergoing surgery in adulthood.

(Barmeyer 2010)

Follow-up status after operative ASD closure:

Patients with operated ASD II have a prognosis comparable to the general population if

• the operative closure was performed before the age of 24

or

• preoperatively the systolic pulmonary pressure was < 40 mmHg

(Herald 2019)

• The 10-year survival is 95% for patients whose surgery was performed after the age of 40 and 84% for conservatively treated patients with a Qp: Qs > 1.5: 1 (Pinger 2019).

• In the early postoperative phase a postcardiotomy syndrome (also known as Dressler syndrome ) often occurs

• Patients who underwent surgery in childhood showed no complications such as apoplexy, heart failure, pulmonary hypertension and mortality after more than 26 years. Only symptomatic atrial arrhythmias occurred in 6% after 15 years.

(pinger 2019)

• In patients who are operated on in adulthood, dilatation of the right heart and the abnormal movement pattern of the ventricular septum often persist.

• Disorders of left ventricular function are possible

• A reduced pumping function of the right chamber and impaired compliance can occur

• The increased pressure in the pulmonary arteries can remain, progress or even reappear

• An obstruction of the superior vena cava can develop after the closure of a sinus venosus defect

• Cardiac arrhythmias can occur (atrial fibrillation, atrial flutter, supraventricular reentry tachycardia are particularly common, which may require ablation)

• A re-shunt or a residual shunt can occur in the atrial region

• Brain embolisms

(Herald 2019)

• There are no contraindications against pregnancy
• There are also no contraindications against hormonal contraceptives
• There are no restrictions against physical activities or sports, provided that:
  • there is no pulmonary hypertension
  • no significant dysfunction of the right ventricle is detectable
  • no significant arrhythmias are present
  • Follow-up examinations are not necessary in the case of early surgery (although the exact period is not defined in more detail)
• The upper age limit for invasive procedures is unclear

(ping 2019)

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