elevated wedge often greater than 20 mm Hg This is compared with the direct left atrial pressure or the left ventricular end-diastolic pressure The pulmonary artery wedge angiogram can be performed using a 12-mm syringe on a balloontipped catheter The syringes filled first with 4 mL of saline and then carefully, without mixing the solution, 8 mL of contrast This injection is usually slow and steady, and if complete occlusion of the pulmonary veins is observed, then the injection should be stopped due to the risk of pulmonary venous capillary rupture When pulmonary venous capillary rupture occurs, the extravasation of contrast and blood will be seen clearly in the airways on fluoroscopy If this occurs, the balloon should be deflated, a cuffed endotracheal tube can be placed in the unaffected lung, and the patient's anticoagulation should be reversed Left Atrium Saturations The most consistent value is obtained at the mid-posterior LA away from the left atrial appendage For children, a significant decrease in saturations is considered less than 5%, suggesting the presence of a right-to-left shunt Pressures ■ A wave: atrial systole during the open mitral valve (Fig 17.11) Normal: children 4 to 6 mm Hg and adults 6 to 10 mm Hg and increased in left ventricular hypertrophy, left ventricular noncompliance, mitral stenosis, atrioventricular dissociation FIG 17.11 Left atrial tracing with A wave and V wave measurement ■ V wave: filling against closed mitral valve Normal: children 6 to 8 mm Hg and adults 9 to 14 mm Hg and increased in mitral regurgitation, left-to-right atrial septal defect ■ Normal mean LA pressure = children 3 to 7 mm Hg and adults 6 to 12 Left Atrial Appendage Knowing the location of the left atrial appendage is important because, in normal anatomy, it is an anterior leftward structure while the pulmonary veins are posterior and the mitral valve is inferior Mitral Valve Mitral Valve Atresia This is predominately seen with hypoplastic LV and single ventricle anatomy Mitral Valve Stenosis Measurement of the A wave and mean gradient is important This can be achieved with a catheter in the LA across the atrial septum or by using a pulmonary artery wedge catheter simultaneously with a pigtail catheter retrograde from the arterial access and into the left ventricular cavity Left Ventricle and Left Ventricular Outflow Tract (LVOT)13 General LVOT lesions typically refer to obstructive lesions below, at, or above the level of the aortic valve, including the subvalvar region, valvar aortic lesions, and supravalvar aortic stenosis (AS) A decrease in oxygen saturations suggests the presence of a right-to-left shunt Subaortic Stenosis Subaortic stenosis refers to a discrete fibrous ring or a fibromuscular narrowing beneath the aortic valve and commonly distal to any VSD Cardiac catheterization can also be used as a diagnostic tool when there is a need for direct measurement of the hemodynamic gradients to determine the timing or need for surgical repair Diastolic Dysfunction Diastolic dysfunction refers to elevation in the end-diastolic pressure and/or elevation in the diastolic pressure, such that it does not come down to the zero line This should be carefully assessed to ensure that this is not a simple error in zeroing of the line or related to catheter position or air in the line This can occur secondary to primary systolic dysfunction of the LV or related to long-standing LVOT or aortic arch obstruction, systemic hypertension, or significant volume load of the left heart Hypertrophic Cardiomyopathy Hypertrophic cardiomyopathy patients have hypertrophy of the myocardium in