​Kembara Xtra - Medicine - Atrial Septal Defect

​Kembara Xtra - Medicine - Atrial Septal Defect 
Anatomically, the atrial septum has a hole that allows blood to pass between the two atria.
– Because there is no missing septal tissue, a patent foramen ovale is not regarded as an atrial septal defect (ASD).
Types are categorized by location and abnormal embryogenesis (1). 75% of cases involve an ostium secundum defect in the midseptum; 15-20% involve an ostium primum defect in the inferior septum, which is linked to a cleft mitral valve and a failure of endocardial cushion development; and 5-10% involve a sinus venosus defect in the superiorposterior septum, which is close to the orifice of the superior vena cava and is
- 1%: coronary sinus defect, which is characterized by the absence of the whole common wall between the coronary sinus and the left atrium.
The degree of Left-to-Right shunting in late ventricular systole and early diastole is dependent on the extent of the defect and the relative pressures of the two ventricles.
- Leads to increased blood flow through the right-sided circulation, which eventually results in heart failure and reactive pulmonary hypertension.
Pulmonary and cardiovascular systems are affected.

Child Safety Considerations
The majority of ASD cases are found in children and treated there; the likelihood of spontaneous closure is higher for smaller defects in younger children.

EPIDEMIOLOGY

Incidence: 1/1,500 live births; dominant age: present from birth; female-to-male ratio: 2-4:1; no racial predilection; >90% of all congenital heart lesions in the adult population are caused by ostium secundum alone.
Prevalence

13% of congenital cardiac conditions are ASDs.

PATHOPHYSIOLOGY AND ETIOLOGY
Due to increased left-sided pressures, flow across ASD typically shunts left to right:
- Early ventricular systole with minimal right-to-left shunting, particularly after inspiration
- Right ventricular and pulmonary vascular volume overload, right-sided heart failure, and increased right-sided pressure/pulmonary arterial hypertension can reverse shunt flow (Eisenmenger syndrome), resulting in cyanosis and clubbing.

Genetics Although there are a few uncommon familial occurrences, the majority of cases are spontaneous.
25% of people have Down syndrome, while 5% have chromosomal abnormalities.

RISK FACTORS: Maternal age >35 years; family history; other congenital cardiac abnormalities; gestational exposures: thalidomide; alcohol; smoke; high blood sugar.

CONDITIONS OFTEN Associated with
Approximately 70% of ASDs are solitary, but they can also be a part of more serious structural problems in the heart, like aberrant pulmonary venous return.
May be related to uncommon underlying genetic syndromes such as Noonan syndrome, Down syndrome, Holt-Oram syndrome, Ellis-van Creveld syndrome, VACTERL syndrome, or Holt-Oram (ASD present in 66% of cases),

DISEASE HISTORY

The majority of ASDs are mild, asymptomatic during childhood, and only detectable as an accidental heart murmur during a regular physical examination.
Right-sided heart failure (more advanced, only 10% at diagnosis), tachypnea, recurrent respiratory infections, or failure to thrive may be evident in infants with severe ASDs.
By the age of 40, untreated abnormalities typically start to show symptoms, which can include palpitations (most frequently), exercise intolerance, dyspnea, syncope, peripheral edema, cyanosis, or weariness.
Children and young adults may exhibit exercise intolerance or atrial arrhythmias but are rarely symptomatic.
 

Children and young adults are largely asymptomatic, with the exception of cyanosis and hyperdynamic precordium, which they may occasionally show.
According on the degree of shunting, the signs change.
Cardiac palpation: Right ventricle hyperdynamic precordium; left upper sternal border palpable pulmonary artery pulse
Cardiac auscultation: Fixed, widely split S2 (important physical finding);
Diastolic murmur (pulmonic regurgitation), low-pitched diastolic rumbling (tricuspid flow murmur), and systolic ejection murmur (pulmonic flow murmur) are all heart murmurs.
Systolic regurgitation (murmur in the heartbeat)
 Right-sided heart failure is accompanied with the fourth heart sound.

Eisenmenger syndrome symptoms include:
- Clubbing and cyanosis - Jugular venous edema and distention

DIFFERENTIAL DIAGNOSIS: Right bundle branch block (for widely separated S2), other congenital heart disease


DETECTION & INTERPRETATION OF DIAGNOSIS
Initial examinations (lab, imaging)
The best initial test is a transthoracic echocardiography (TTE) with Doppler imaging of the entire atrial septum, which is sensitive to abnormalities in the sinus venosus (44%) and secundum (89%), primum (100%), and both.
Transesophageal echocardiography (TEE) should be performed if TTE is nondiagnostic or demonstrates right ventricular overload.

Oximetry during rest and exercise: Cyanosis or SpO2 90% may indicate Eisenmenger syndrome (right-to-left shunting). These symptoms might only show up with activity in some patient subgroups.
A normal ECG is not diagnostic, but it may reveal a number of symptoms of right- or left-sided cardiac strain, an inverted P wave in lead III (in the sinus venosus), or a leftward axis (in the ostium primum or sinus venosus).

Tests in the Future & Special Considerations
TEE may be required to describe ASD anatomy and to detect the pulmonary veins; it is frequently used prior to percutaneous closure. Bubble contrast enhancement may be helpful. TEE has exceptional specificity and sensitivity.

Other/Diagnostic Procedures
Echocardiography is the initial line, as was already mentioned.
Cardiac catheterization is used to diagnose ASDs, detect coexisting cardiac disease, and determine whether there is hypertension or pulmonary vascular resistance (especially if surgery is being considered). Young individuals should not have this treatment unless it is necessary for a planned closure, simultaneous evaluation of another condition, or when other imaging techniques are insufficient.
Cardiac magnetic resonance is a noninvasive adjunct to echocardiography that can be used to assess right ventricular function, shunt fraction, and abnormalities in the sinus venosus and pulmonary veins.
Chest x-rays can be utilized to identify right ventricular or pulmonary artery enlargement. Exercise testing can be performed to track change over time.
Cardiac CT: may help to further identify ASD but exposes the patient to a lot of radiation

GENERAL MEASURES/TREATY
75% of tiny secundum ASDs (8 mm) will spontaneously close by the age of 18 months, however close follow-up is necessary.
Primum and sinus venosus problems frequently necessitate surgical closure.

First Line: MEDICATION
Treatment of secondary cardiac or pulmonary vascular disease - Cardioversion, sinus rhythm control, or anticoagulation for atrial fibrillation/supraventricular tachycardia (SVT) - Treatment of heart failure using diuretics, oxygen, digoxin, etc.
- Remodeling therapy for patients with severe pulmonary arterial hypertension using prostaglandins, endothelin blockers, and PDE-5 inhibitors
Adults with severe or worsening pulmonary vascular disease should think about receiving pulmonary vasodilator therapy.
Next Line
Aspirin alone or a combination of aspirin and clopidogrel 75 mg for at least 6 months is advised to prevent thrombus formation after device deployment. Antibiotic prophylaxis is NOT advised for unrepaired/isolated ASDs or as prophylaxis against infective endocarditis during dental procedures.

SURGICAL AND OTHER PROCEDURE

By the age of two years old, the majority of tiny secundum defects (less than 6 mm) spontaneously close. Closure is typically recommended for children with malformations > 8 mm and for children > 5 years old with defects of any size and associated symptoms.
Before the age of two, secundum defects are not advised to be closed in asymptomatic patients due to the likelihood of spontaneous closure. Additionally, it should not be used in individuals with severe, irreversible pulmonary hypertension who are not receiving ongoing shunt therapy.
Adults with right heart enlargement, pulmonary systemic flow ratio of 2:1 (or >1.5:1 and 21 years old per the AHA), or symptoms such as orthodeoxia/platypnea or paradoxical embolism may benefit from secundum closure via percutaneous transcatheter device or surgery to lower subsequent morbidity and mortality (1).
Surgical repair is the norm for a sinus venosus, coronary sinus, or primum ASD. Percutaneous closure with a closure device is thought to be the preferred therapy of secundum ASD in adults. therapy with a closure device has no substantial impact on aortic/mitral valve function.
It is secure and efficient, and long-term clinical follow-up has been excellent. Furthermore, the function of the mitral or aortic valves is not considerably impacted by the use of a closure device.
For individuals with recurrent or persistent atrial tachyarrhythmias, the maze procedure may be considered either before or after closure.
CONTINUING CARE AFTERCARE RECOMMENDATIONS
Depending on the physiologic stage of the problem, outpatient cardiology visits might range from every three months to every five years. ECGs can range from every one to every five years.

TTE: depending on the physiologic stage of the defect, every 1 to 5 years; exercise stress test: for severe disease, every 6 to 24 months.

patient observation
Follow up with generally healthy, asymptomatic youngsters until the defect has closed or shrunk noticeably.
ASDs treated as adults might necessitate ongoing long-term follow-up.
ASDs treated throughout childhood typically don't have any long-term issues.
The risk of maternal and fetal death during pregnancy is raised in cases with unrepaired ASD/Eisenmenger syndrome, whereas pregnancy is often tolerated in situations of repaired/small unrepaired ASDs.
Recommend consultation for people with untreated ASDs before going scuba diving or ascending a mountain.

EDUCATION OF PATIENTS

Consult the websites of the American Heart Association or Mayo Clinic ASD for patient education resources on this subject.


PROGNOSIS
ASD closure in adults who are asymptomatic, hardly symptomatic, or symptomatic lowers morbidity, especially if done before age 25.
Delaying ASD repair until late adolescence may not reduce the long-term risk of developing atrial arrhythmias in the future.
In one trial, pretreatment with PAH medications and pulmonary remodeling treatments led to a >20% reduction in pulmonary resistance after ASD closure.

Unoperated ASDs can result in mortality rates of up to 25% by 27 years and up to 90% by 60 years, as well as higher rates of atrial arrhythmias, decreased functional capacity, and more severe pulmonary arterial hypertension.

COMPLICATIONS
Untreated infections raise the chance of developing congestive heart failure, stroke, atrial arrhythmias, and pulmonary, cerebral, and endocarditis infections. Rarer side effects include paradoxical embolism and pulmonary arterial hypertension/Eisenmenger syndrome.

 After a surgical correction, there is a 5% chance of late-onset arrhythmias occurring 10 to 20 years later, a 10% to 13% chance of perioperative atrial tachyarrhythmias, and an increased chance of arrhythmia-related embolic events.

Device closure risks include device embolization (1%), device erosions, heart perforation, thrombus development, endocarditis, and supraventricular arrhythmias.