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Atrial and Ventricular Septal Defect Closure
Atrial Septal Defect Closure
Aside from the bicuspid aortic valve, an atrial septal defect (ASD) is the most common congenital cardiac anomaly in adults with an approximate prevalence of 1 per 1000 individuals. This chapter focuses on echocardiographic imaging during ASD closure. Embryology, classification, diagnosis, and hemodynamic significance of ASDs are discussed in detail in the congenital heart disease section of this book. Briefly, there are four main types of ASDs (listed in decreasing order of frequency): secundum ASD, primum ASD, sinus venosus ASD, and unroofed coronary sinus. When indicated, ASDs can be closed either surgically or via a percutaneous approach. According to most recent guidelines, the primary indication for ASD closure is the presence of right atrial or right ventricular enlargement, especially in the presence of symptoms (classes I and II). Secundum ASDs are the only ASDs for which percutaneous closure with current devices is indicated. All other ASDs are closed surgically in eligible patients. Indications for percutaneous or surgical ASD closure in adults with isolated secundum ASD are summarized in Table 169.1 . The primary contraindication of ASD closure is the presence of irreversible, severe pulmonary arterial hypertension and no evidence of left-to-right shunt (class III). During ASD closure attempts, an occlusion test may be performed. ASD is transiently closed using sizing balloon while the patient’s hemodynamic parameters are monitored. Closure is aborted if hemodynamic instability or signs of acute pulmonary edema develop.
TABLE 169.1
Indications for Percutaneous or Surgical Closure of Isolated Secundum Atrial Septal Defect in Adults
| Class I | Class IIA | Class IIB | Class III | |
|---|---|---|---|---|
| Symptoms | Symptomatic | Asymptomatic | ||
| Right heart enlargement | Present | |||
| Qp:Qs ratio | >1.5:1 (net left > right shunt) | <1.0 (net right > left shunt) | ||
| PA pressure | <50% systemic | >50% systemic | >2/3 systemic | |
| PVR | <1/3 systemic | >1/3 systemic | >2/3 systemic | |
| Cyanosis at rest or with exercise | Absent | |||
PA, Pulmonary artery; PVR, pulmonary vascular resistance; Qp, pulmonic flow; Qs, systemic flow.
Surgical Atrial Septal Defect Closure
The earliest surgical closure of an ASD was reported in the early 1950s. Surgical ASD closure was the first successful open-heart operation (performed under general hypothermia and inflow occlusion) even before the advent of cardiopulmonary bypass (CPB). Subsequently, ASD closure became the very first type of cardiac surgery to use CPB. Surgical closure can be accomplished by either direct suture or using a patch. It is recommended that the surgical ASD closure be performed by surgeons with expertise and special training in congenital heart disease. Surgery remains the only recommended means of closing primum, sinus venosus, and coronary sinus types of ASDs. Surgery is an alternative to percutaneous closure of secundum ASDs.
Percutaneous Atrial Septal Defect Closure
Percutaneous closure of an ASD was first described in the mid-1970s. Currently, percutaneous closure has become the most common means of repairing secundum ASDs. All currently available ASD closure devices in the United States are only approved for secundum-type ASDs. These devices have a similar basic structure; they all contain two disks connected by a waist. Some are approved for simple secundum ASDs with a solitary hole, whereas others are specifically designed for secundum ASDs with multiple holes, referred to as fenestrated or cribriform (sieve-like) ASDs. The three most commonly used devices ( Fig. 169.1 ) are:
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The Amplatzer atrial septal occluder (St. Jude Medical) is used to close nonfenestrated secundum ASDs. It contains a larger left atrial disk connected to a smaller right atrial disk. The waist connecting the two disks ranges from 4 to 38 mm in diameter. When selecting an appropriate device size, the waist diameter of the device should correspond to the ASD diameter.
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The Gore Cardioform atrial septal occluder (WL Gore & Associates) contains two equal-sized disks connected by a spiral shaft; disk diameter ranges from 15 to 35 mm. An appropriately selected Gore device should have a disk diameter that at is at least twice the ASD diameter.
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The Amplatzer multifenestrated atrial septal occluder (St. Jude Medical) contains two equal-sized disks connected by a thin shaft for use with cribriform ASDs. Disk diameters range from 18 to 35 mm. An appropriately selected device should have a disk size of a sufficient diameter to cover the entire ASD.
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