Atrial septal defect natural history
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Natural history
As many atrial septal defect patients are asymptomatic, it is common to survive into adulthood without any need for intervention. Adulthood, however, can lead to onset of symptoms and altered life expectancy. Beyond 40-50 years of age, survival without intervention is under 50% with an attrition rate of about 6% per year. Complications may onset later in life and include associated conditions such as atrial fibrillation, pulmonary hypertension, and stroke.
Complications
In some patients, surgical intervention may result in developing complications such as:
- Atrial fibrillation
- Infective endocarditis (primarily within the first 6 months post-surgery)
- congestive heart failure
- Arrhythmia
- Pulmonary hypertension
- Cyanosis
- Paradoxical embolization
- Stroke
Complications involving comorbidity
Many atrial septal defect patients are at risk for developing comorbid complexes with the following conditions:
- ====Atrial septal defect and atrial fibrillation====
50-60% of atrial septal defect patients over the age of 40 exeperience atrial fibrillation issues. This late-onset is correlated as a major cause in morbidity and mortality. Some research suggests that pharmacologic therapy such as anticoagulants can assist with lower mortality risks associated with atrial flutter.
- ====Atrial septal defect and pulmonary hypertension====
15-20% of atrial septal defect patients develop pulmonary hypertension. Characteristically rare during youth, pulmonary hypertension has been observed in 50% of patients over the age of 40. In particular, Eisenmenger syndrome patients are at risk for severe pulmonary obstruction and can result in significant reversal of blood shunting from right-to-left. This can lead to systemic circulation conditions such as hypoxemia and cyanosis.
- ====Atrial septal defect and right heart failure====
Due to the nature of the defect, atrial septal defect patients of all ages experience strain on the right-heart complex. Patients may experience heart failure as a result of the cardiac volume overload the right side of the heart experiences during left-to-right shunting.
- ====Atrial septal defect and stroke====
Even without surgery, as many as 5-10% of all atrial septal defect patients experience thromboembolic events such as stroke and transient ischemia. Research suggests that paradoxical emboli in atrial septal defect patients is mutually exclusive of defect size and can potentially occur in all patients.
Prognosis
Most atrial septal defect patients live to advance in age. The mortality rate for surgical intervention repair is less than 1% for atrial septal defect patients under the age of 45, with no history failure or pulmonary artery pressure issues. Morbidity, too, is low. As atrial septal defect patients age, mortality rates of surgical intervention repair increases linearly with age and pulmonary artery pressure. If an atrial septal defect is detected and diagnosed early in life, surgery is most successful when performed at 2-4 years of age. Repair is normally only performed in youth with clinically significant complications. Surgery is still advised for all patients with uncomplicated ASDs with clinically significant shunting from left-to-right. Patients with normal pulmonary artery pressure have comparable age- and sex-matched 30-year survival rates until the age of 40. Patients with pulmonary artery pressure issues may experience a lower survival rate. Life expectency in surgical therapy older patients, though, is better than that of patients with medical therapy. In a small population of patients over the age of 60, presenting without comorbodities, still benefit from surgical intervention.
In general, surgical intervention of an ASD is associated with an increase in mortality. However, the age of the patient at the time of surgical closure is the single most important predictor of development of potentially serious life-threatening comorbidities. Most types of atrial septal defects, when repaired with surgical intervention, are associated with low mortality and low morbidity risks. In children, surgical repair can even result in reduction in the right ventricular size from abnormal to closer to normal. Size reduction is not as common in adults with only 20% of all repairs experiencing changes in dimensions. Patients with tricuspid regurgitation and right ventricular failure may experience lifelong symptoms and may have differed long-term outcomes. Complications are more common in older atrial septal defect patients after surgical intervention. It is believed that prognosis is influenced by the long-term effect of volume overload on the chambers of the right side. It is also associated with the volume overload as a result of right atrial enlargement and of pulmonary hypertension. These particular strains on the right chamber of the heart lead to increased risk for atrial arrhythmia and stroke. As many as 22% of late deatsh can be attributed to cerebrovascular events. Age at repair as well as preoperative status, such as NYHA class III and IV heart failure, are independent predictors of mortality.