FIGURE 9.1 A-C, Three sets of right atrial pressures in a patient with severe aortic stenosis and radiation-induced pericardial disease s/p pericardiectomy. The panels reveal normal, moderately elevated, and severely elevated right atrial pressures, all recorded on a 5 mm Hg scale. The tracings were taken a few seconds apart, with the transducers positioned above, at, and below the level of the patient’s heart. Failure to compulsively align the transducer with the level of the patient’s heart produces substantial error in hemodynamic recordings. Note the steep Y descent, which falsely appears to have an excursion below zero in the tracing at left (A). Reproduced with permission from Turi ZG. Pitfalls in the evaluation of hemodynamic data. In: Moscucci M, ed. Grossman & Baim’s Cardiac Catheterization Angiography and Intervention. Philadelphia: Lippincott Williams and Wilkins; 2014.

FIGURE 9.2 Graph showing minimum left ventricular pressure (LVPmin) measurement error due to hydrostatic pressure influences attributable to a midchest reference position as a function of patient anterior-posterior (A-P) chest thickness. H indicates measurement taken at the uppermost blood level in the left ventricle. Reproduced with permission from Courtois M, Fattal PG, Kovács SJ Jr, Tiefenbrunn AJ, Ludbrook PA. Anatomically and physiologically based reference level for measurement of intracardiac pressures. Circulation. 1995;92:1994-2000.