Andersons pediatric cardiology 1122

valvuloplasty (Video 42.4) FIG 42.29 Basic procedural stages of balloon pulmonary valvuloplasty (A-plane projection to the left, lateral to the right) Top, Baseline right ventricular angiogram documenting a doming pulmonary valve (annulus measured at hinge points) Middle, Balloon inflation with visible waist (midway through inflation) Bottom, Right ventricular angiogram after balloon dilation Balloon pulmonary valvuloplasty is usually performed using fluoroscopic guidance, even though it is possible to perform the procedure under echocardiographic guidance alone.80 However, there is evidence that echocardiographic pulmonary valve measurements are smaller on average than angiographic measurements, with a significant variation in this discrepancy; this limits the ability to choose the appropriate balloon size safely.29 Fluoroscopy times are usually very short, with results from the C3PO registry documenting the median fluoroscopy time to be 20 minutes (75th/95th centile 32/68 minutes).81 The median total air Kerma was 87, 133, 244, 319, 1781 mGy for patients less than 1, 1 to 4, 5 to 9, 10 to 15, and above 15 years of age, respectively Access to the circulation is most commonly through a femoral venous puncture In patients with problems of vascular access due to venous thrombosis, other techniques can be employed, including use of the jugular,82 axillary,83 or hepatic84 veins Although balloon valvuloplasty can be performed percutaneously in patients weighing less than 1.5 kg,85 an alternative hybrid approach may be more suitable in selected patients, in particular in extremely low-weight infants with a poorly functioning and dilated right ventricle, in whom a percutaneous approach may not be well tolerated.86 Right heart catheterization is performed using either a curved end-hole catheter, such as a right coronary catheter or one that is cobra shaped, or a balloon-tipped catheter Transvalvar peak-to-peak gradient and the right ventricle–to–systemic arterial pressure ratio are carefully documented It is important to be attentive to the presence of subvalvar and/or supravalvar stenosis during the hemodynamic evaluation These gradients may be difficult to distinguish from valvar gradients using a standard end-hole catheter, and the use of a pressure wire should be considered when coexisting sub- or supravalvar stenosis is suspected (Fig 42.30).87 The advantage of using a pressure wire is that the recording element is located at some distance from the distal end of the wire, thereby enabling a withdrawal through the supravalvar, valvar, and subvalvar areas while the distal tip of the wire is still positioned in the main