4.Atrial septal defect(ASD) Flashcards
ASD definition?
Corresponds for a certain type of communication between the atria.
It is more common in females.
Where ASD can appear?
The atrial septal defect
can be in the upper or lower part of the septum.
What does ASD represent?
Represents a state where foramen ovale is closed only functionally from the
embryonal period. It is known as foramen ovale persistents (ostium secundum ASD). In some cases it
is closed anatomically but in such a way that there will be an opening which remains and this opening
is of different sizes. This case is known as foramen ovale apertum.
The size of the defect and the pressure changes in the atria will
determine the amount of blood flowing from the left to the right atrium.
Ostium primum defect?
Less commonly, an ASD appears in the inferior portion of the interatrial septum, adjacent to the AV
valves. Named as ostium primum defect, this abnormality results from the failure of the septum
primum to fuse with the endocardial cushions.
Sinus venosus defect?
Sinus venosus defect and is closely related to ASDs but is morphologically distinct. This condition
represents an “unroofing” defect with absence of normal tissue between the right pulmonary vein(s)
and the right atrium but is technically not a deficiency of the anatomic atrial septum
Patent foramen ovale (PFO)?
A PFO is usually clinically silent because the one-way valve, though not sealed, remains functionally
closed since the left atrial pressure is higher than that in the right atrium. However, a PFO takes on
signifi cance if the right atrial pressure becomes elevated (e.g., in states of pulmonary hypertension
or right-heart failure), resulting in pathologic right-to-left intracardiac shunting.
In that case,
deoxygenated blood passes directly into the arterial circulation.
PFO is implicated in patients?
Who has suffered a systemic embolism (e.g., a stroke). This situation, termed
paradoxical embolism, occurs when thrombus in a systemic vein breaks loose, travels to the right
atrium, passes across the PFO to the left atrium (if right-heart pressures are elevated, at least
transiently), and then into the systemic arterial circulation.
Blood flow in atrial septal defect?
The flow of blood through the defect in the atrial
septum during diastole, leads to an increment of the filling of the right ventricle and hence an
increment of the blood flow through the pulmonary area. More blood flows to the left atrium yet
once again part of it is transferred to the right atrium via the defect and is recirculated through the
lung field. In long lasting and markedly increased pulmonary blood flow there will be an increased
arterial vascular tonus of the lung field. So the arterial blood pressure is gradually increasing in the
pulmonary artery and as a consequence of this there will be right ventricular hypertrophy, then to an
increment in the connective tissue and finally even the formation of atherosclerosis in the small
circulation.
Those
patients are not symptomatic from the beginning. Usually there are some respiratory infections.
Problems?
In older ages there are cardiorespiratory problems. Later there might be atrial arrhythmias and
pulmonary hypertension.
Right ventricular hypertrophy can present in children
