A HANDA Diagnosis of atrial septal defects (ASDs) is largely by echocardiography. Cardiac CT and MRI can give valuable information regarding quantification of shunt and haemodynamics. Echocardiography is used for imaging guidance during percutaneous transcatheter closure of ASDs and patent foramen ovales (PFOs). Real-time intraprocedural echocardiography TTE, TEE, 3D imaging or ICE provide vital information before, during and after deployment of the device.1 Although each modality has its own advantages and disadvantages, echocardiographic augmentation of fluoroscopic imaging offers significant information in individual patient selection, device selection, procedural guidance, monitoring for complications and assessment of the results. Regardless of modality, baseline transthoracic echocardiography is essential in the monitoring of transcatheter procedure guidance and post-procedural complications. A list of all major complications of transcatheter closure and the appropriate imaging modality to assist with the diagnosis is provided in Table 8.1. Transthoracic echocardiography is the baseline invasive imaging modality for percutaneous transcatheter closure and could be adequate for procedure guidance in smaller patients.2 Its limitations include suboptimal imaging in larger patients and interference of the echocardiographic probe with fluoroscopy.2 In addition, the implanted device creates artefacts, frequently precluding interrogation of the lower rim of the atrial septal tissue above the inferior vena cava (IVC). Transesophageal echocardiography provides detailed imaging findings during percutaneous transcatheter closure. General anaesthesia can be used whenever TEE is performed to enhance patient comfort and improve imaging anatomy and better delineation of the intended structure for analysis. In addition to the anaesthetist, a dedicated echocardiographer is optional to perform the TEE during the closure procedure. In selected cases conscious sedation can be used rather than general anaesthesia. Intracardiac echocardiography has emerged as an alternative imaging modality for transcatheter closure guidance. ICE imaging is comparable to TEE and more helpful for LA structures and the postero-inferior rim of the septum.3 The ICE system requires additional logistics, especially 8-F to 11-F sheaths. If the patient weights more than 35 kg, then sheaths for both the device and the ICE system can be placed in the same femoral vein using two separate punctures several millimetres apart. In thinner patients, venous access for the ICE catheter should be obtained in the contralateral vein. Although separate echocardiographic expertise is helpful for providing assistance during the procedure, it is not always required as the interventionalist performing the septal closure can also manipulate the catheter. The procedure does not require general anaesthesia. Also shorter procedure and shorter fluoroscopy times are possible, and the cost is lower compared to TEE-guided percutaneous closure, where use of general anaesthesia is essential.4 Three-dimensional ICE has been introduced recently, and the preliminary results have started emerging from evaluating patients with structural heart disease. Three-dimensional TEE offers live real-time imaging of the septum, providing a comprehensive analysis of the defect and its relationship to the surrounding structures.5 Direct visualization of the deployed device from both sides of interatrial septum augments the post-deployment assessment of the defect and efficacy of the device closure and potential complications associated with the procedure. All patients undergoing percutaneous transcatheter closure of septal defects require pre-procedural echocardiographic imaging, with either TTE or TEE, to assess the septal anatomy and determine the suitability of an atrial defect for device closure.2 This includes a detailed echocardiographic investigation of the entire IAS and surrounding structures using multiple sequential planes, as previously defined. The different type of ASD (ASD type, ASA, PFO), the number of defects adjacent to main defect (up to 13% of patients could have more than one defect), defect size, its location, morphology and the surrounding atrial septal tissue (rims) should be delineated (Table 8.1). Other associated abnormalities of the adjoining structures such as the pulmonary veins, IVC, SVC, coronary sinus, eustachian valve and AV valves should be evaluated. The septal defect and surrounding rims of atrial tissue should be carefully evaluated. Using TEE with the midesophageal four-chamber view (starting from 0″ multiplane and moving in 15″ multiplane increments), the inferior–anterior and superior–posterior rims can be defined (Figures 8.1–8.3). The anterior rim or the aortic rim of the atrial septal defect and the posterior rim are measured in the midesophageal short-axis view (30″–45″ multiplane and moving in 15″ increments). The midesophageal bicaval view (110″–130″) is used to visualize the superior as well as inferior rims. Imaging with 3D TEE allows for acquisition of similar sets of data but without the need for serial assessment in multiple stepwise views (Figures 8.4 and 8.5). Also transgastric imaging could be required to visualize the inferior rim of an ASD in some cases and can be used to define the relationship of the inferior aspects of the device and the IAS.4 Figure 8.1
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Role of echocardiography in transcatheter device closure
IMAGING MODALITIES IN TRANSCATHETER GUIDANCE
Transthoracic echocardiography, transesopahageal and intracardiac echo
INTRAPROCEDURAL GUIDANCE OF TRANSCATHETER INTERVENTIONS6
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