cardiovascular disorders
Cardiac Catheterization
Procedure for Cardiac Catheterization
Many but not all preprocedure protocols require patients to fast for 4 to 6 hours before cardiac catheterization. Most patients do not require overnight hospitalization unless a therapeutic intervention is also done. Left heart catheterization is most commonly used to assess Coronary artery anatomy and presence of coronary artery disease Left heart catheterization is also used to assess Aortic blood pressure Aortic valve function Left ventricular pressure and function Mitral valve function Systemic vascular resistance Left heart catheterization is done via femoral, subclavian, radial, or brachial artery puncture, with a catheter passed into the coronary artery ostia and/or across the aortic valve into the left ventricle (LV). Catheterization of the left atrium (LA) and LV is occasionally done using transseptal perforation during right heart catheterization. Right heart catheterization is commonly used to measure Right atrial pressure Right ventricular pressure Pulmonary artery pressure Pulmonary artery occlusion pressure (pulmonary artery wedge pressure) (PAOP—see figure The most frequent indications for right heart catheterization are to assess hemodynamics, diagnose pulmonary hypertension, guide therapy, and assess need for cardiac transplantation or mechanical cardiac support (eg, a ventricular assist device). PAOP approximates left atrial and left ventricular end-diastolic pressure. In seriously ill patients, PAOP helps assess volume status and, with simultaneous measurements of cardiac output, can help guide therapy. Right heart catheterization is also useful for assessing cardiac filling pressures, pulmonary vascular resistance, tricuspid or pulmonic valve function, intracardiac shunts, and right ventricular pressure. Right heart pressure measurements may help in the diagnosis of Overview of Cardiomyopathies , The Procedure is done via femoral, subclavian, internal jugular, or antecubital vein puncture. A catheter is passed into the right atrium, through the tricuspid valve, into the right ventricle, and across the pulmonary valve into the pulmonary artery. Selective catheterization of the coronary sinus can also be done. Hemodynamic assessment via right heart catheterization during exercise is increasingly being done as part of the workup for dyspnea of uncertain etiology. The test can be done at the same time as cardiopulmonary exercise testing, called invasive cardiopulmonary exercise testing. This is considered the standard for diagnosis of cardiac limitation to exercise but is currently available at relatively few centers. An exercise right heart catheterization should be considered in patients at intermediate pretest probability for Classification if the diagnosis is uncertain after an initial evaluation. An increase in the PAOP > 25 mm Hg confirms the diagnosis when patients have signs and symptoms of heart failure irrespective of left ventricular ejection fraction. The phases of the cardiac cycle are atrial systole (a), isometric contraction (b), maximal ejection (c), reduced ejection (d), protodiastolic phase (e), isometric relaxation (f), rapid inflow (g), and diastasis, or slow LV filling (h). For illustrative purposes, time intervals between valvular events have been modified, and the z point has been prolonged. In the jugular venous pulse tracing, the A wave represents atrial contraction at end-diastole, C wave is the carotid artery impulse or bulging of the tricuspid valve into the right atrium in early systole, V wave is the increase in pressure and volume of right atrial filling in late systole and early diastole, X and X' descents represent movement of the lower part of the right atrium toward the ventricle with X' at end-systole, and the Y descent is tricuspid valve opening and ventricular filling in diastole. AO=aortic valve opening; AC=aortic valve closing; LV=left ventricle; LA=left atrium; RV=right ventricle; RA=right atrium; MO=mitral valve opening. 