cardiac catheterization

Cardiac catheterization can be performed as right heart catheterization (RHC) or left heart catheterization (LHC). RHC involves passing a catheter through venous access (femoral or internal jugular vein) into the right atrium, right ventricle, pulmonary artery, and pulmonary capillary wedge position (Swan-Ganz catheter) to measure right atrial pressure, RV pressure, PA pressure, and pulmonary capillary wedge pressure (PCWP), which estimates left atrial pressure. It's used to diagnose and manage heart failure, pulmonary hypertension, shock, and valvular disease, and to calculate cardiac output (via thermodilution or Fick method) and shunt fractions (oxygen step-up in ASD/VSD).

LHC involves arterial access (femoral or radial artery) with retrograde catheter advancement through the aorta into the left ventricle, allowing measurement of LV pressures, aortic pressures, and coronary angiography—the gold standard for diagnosing coronary artery disease (CAD). Contrast is injected into coronary arteries under fluoroscopy to visualize stenoses, which can be treated with percutaneous coronary intervention (PCI)/stenting in the same session.

Key clinical indications: acute coronary syndrome (STEMI requires emergent LHC/PCI), stable angina with positive stress test, evaluation of valvular disease severity (e.g., aortic stenosis gradients), constrictive pericarditis vs restrictive cardiomyopathy (via simultaneous RHC/LHC pressure tracings), and pre-transplant evaluation.

Complications include vascular access site bleeding/hematoma, pseudoaneurysm, arterial dissection, contrast-induced nephropathy, arrhythmias, and rarely stroke or MI. Hemodynamic calculations frequently tested include Fick principle for cardiac output, Gorlin equation for valve area, and shunt calculations using oxygen saturation differences between chambers.

USMLE relevance: Understand normal pressure values in each chamber, PCWP as a surrogate for LA pressure, and classic hemodynamic patterns (e.g., elevated PCWP in LV failure, step-up in O2 saturation in left-to-right shunts, equalization of diastolic pressures in constrictive pericarditis and tamponade).