Atrial Septal Defect
Anatomy of heart
Heart located in front and left side of the chest near to the apex beat.
Superiorly, an imaginary line passing through the jugular notch ,
In inferiorly, a parallel line passing through the xiphoid process
bilaterally, two imaginary vertical to midclavicular lines both sides.
Heart composed by cardiac muscle which is striated but involuntary and have intercalated disc.
Heart has 4 Chambers in human :
The right atrium receives non oxygenated blood from the superior venacava and inferior venacava and pumps it to the right ventricle through the tricuspid valve.
The right ventricle get blood from the right atrium and pumps this non oxygenated blood to the lungs for oxygenation . The left atrium receives oxygenated blood from the lungs (after oxygenation ) and pumps it to the left ventricle.The left ventricle (more Powerful than another chmaber) pumps oxygenated blood through the Arch Of Aorta in the whole body by powerful contraction.
Heart covered by a membrane that’s called pericardium.
Landmarks of Heart: Thoracic 5 to thoracic 8 vertebrata (supine), Thoracic 6 toThoracic 9 (erect)
Left atrium
Receives nutrient rich oxygenated blood from the lungs via the four pulmonary veins.
Right atrium
Receives poor nutrient rich deoxygenated blood from the systemic circulation via the venacava.
left ventricle
Receives oxygenated blood from left atrium
Then pump to the arch of aorta.
Right Ventricle
Receives non oxygenated blood from right atrium then pump into the Pulmonary artery.
The heart is at the center of the cardiovascular system, the heart pumps blood through vassels in the body to the target target tissue. It is a pyramidal organ made up of two muscular pumps that are
1) left heart and
2) Right Heart
an upper part of the chamber that receive incoming non oxygenated blood , called the atrium, and a lower part of the chamber thats pump blood out of the heart through the Aorta called the ventricle.
Circulation of blood :
Systemic circulation:
Blood pump left ventricle to arch of aorta
⬇️
Pulmonary circulation:
blood pass through the Right ventricle
⬇️
Pulmonary aorta
⬇️
Lungs
⬇️
Pulmonary vein
⬇️
Left atrim
⬇️
Left ventricle
The heart have three three muscular layers of tissue. The inner layer is known as the endocardium and outer layer is the epicardium. Between those two layers is known as the myocardium which is more thik than another.
The thickness of the middle layer myocardium varies between regions of the heart.
the ventricles are altime thicker than the atria.
the left chambers are more thicker than the right Chamber , Left ventricle 3 times thicker than right ventricle due to pumps blood against greater resistance.
the heart needs own circulation network which is known as the coronary circulation by coronary artery and vein. The coronary arteries are arising from the base of the ascending aorta.
Coronary artery gives numerous branches that supply of the heart. There are several venous tributaries drain poor nutrient deoxygenated blood from the heart and back it mainly to the right atrium; some vein have been shown to drain to the right ventricle.
Fetal circulation :
In intrauterine life, a physiological shunting of oxygenated blood enters the right atrium and passes the left atrium by foramen ovale then blood passed to the left ventricle and pump throughout the whole body
Some blood pass right atrium to lungs for oxygenation via Pulmonary trunk then pass to left ventricle.
As a result blood of left ventricle mixed of oxygenated blood and de-oxygenated blood.
that’s called feotal circulation. In Normal condition the gap of foramen ovale repair Normally within three month of extrauterine life.
Atrial septal defects
Atrial septal defects refer to abnormal communications between the left atrium and right atrium. In Normal condition the gap of foramen ovale repair Normally within three month of extrauterine life.
Unluckily, over time, the right atrium will be exposed to relatively higher pressures and its myocardium will hypertrophy and enlargement . If the right atrial pressure increase more than the left atrial pressure, the shunt will be change from ( left to right) to (right to left). As a Result , blood with lower oxygen(more de oxygeneted blood/less oxygeneted blood ) saturation will be passed into the systemic circulation and occurs hypoxemia for low oxygen saturation.
genetic cause of atrial septal defects
- DiGeorge syndrome (microdeletion of 22q11.2),
- Down syndrome (trisomy 21), and
- Ellis-van Creveld syndrome or chondroectodermal dysplasia (mutation of 4p16 )
Types of Atrial septal defect
- Ostium secundum -75%(followed by patent foramen ovale)
- Ostium primum-15%(endocardial cushion defect)
- Sinus venosus-10%
Most common types of Atrial septal defect (ASD) is Ostium secundum
commonly diagnosed in childhood.
60% patients of ASD are female.
Most Commonly seen in female
Clinical feature of ASD :
- Small defect -Asymptomatic
- Large defect-have some symptoms
- Wide and fixed splitting of 2nd heart sound & Soft mid-diastolic Murmur at left sternal border
- Exercise intolerance
- Fatigability
- Increased perspiration
- Failure to thrive or poor weight gain
- Recurrent chest infection
- Dyspnea on exertion
Complications of ASD :
- Pulmonary Hypertension with Eisenmenger syndrome
- Atrial fibrilation
- Pulmonary embolism
- Systemic embolism
- Infective endocarditis
- Recurrent respiratory tract infection
Laboratory investigation :
- Chest X-ray show cardiomegaly, full Pulmonary conus
- ECG change
- 1.in ostium secundum show RBBB with Right axis daviation
- 2.ostium primum show RBBB with left axis daviarion
- 3.RSR pattern in V1
- Echocardiogram show dilated right heart
- CT or CMR maybe helpful
Treatment of ASD :
- Counselling to the parents about ASD, treatment and Prognosis
- Reduce volume overload and prevent congestive cardiac failure by furosemide
- Surgical closure
- Cardiac cathterizetion
