Typically, these devices are placed in the left upper chest and enter the left subclavian vein and electrodes are placed in the right atrium, right ventricle, and coronary sinus (for the left ventricle stimulation). Valve assessment
Echocardiography is a non-invasive method to evaluate the heart valves. However, sometimes the valve pressure gradients need to be measured directly because echo is equivocal for the severity of valve disease. Invasive assessment of the valve can be done with catheterization by placing a catheter across the valve and measuring the pressures simultaneously on each side of the valve to obtain the pressure gradient. In conjunction with a right heart catheterization, the valve area can be estimated. For example, in aortic valve area calculation the Gorlin equation can be used to calculate the area if the cardiac output, pressure gradient, systolic period, and heart rate are known. Pulmonary angiography
Evaluation of the blood flow to the lungs can be done invasively through catheterization. Contrast is injected into the pulmonary trunk, left or right pulmonary artery, or segment of the pulmonary artery. Shunt evaluation
Cardiac shunts can be evaluated through catheterization. Using oxygen as a marker, the oxygen saturation of blood can be sampled at various locations in and around the heart. For example, a left-to-right atrial septal defect will show a marked increase in oxygen saturation in the right atrium, ventricle, and pulmonary artery as compared to the mixed venous oxygen saturation from the oxygenated blood from the lungs mixing into the venous return to the heart.
These methods have drawbacks, but give invasive estimations of the cardiac output, which can be used to make clinical decisions (e.g., cardiogenic shock, heart failure) to improve the persons condition.Cardiac catheterization can be used as part of a therapeutic regimen to improve outcomes for survivors of out-of-hospital cardiac arrest.Cardiac catheterization often requires the use of fluoroscopy to visualize the path of the catheter as it enters the heart or as it enters the coronary arteries. The coronary arteries are known as "epicardial vessels" as they are located in the epicardium, the outermost layer of the heart. The use of fluoroscopy requires radiopaque contrast, which in rare cases can lead to contrast-induced kidney injury (see Contrast-induced nephropathy). People are constantly exposed to low doses of ionizing radiation during procedures. Ideal table positioning between the x-ray source and receiver, and radiation monitoring via thermoluminescent dosimetry, are two main ways of reducing a persons exposure to radiation. People with certain comorbidities (people who have more than one condition at the same time) have a higher risk of adverse events during the cardiac catheterization procedure. These comorbidity conditions include aortic aneurysm, aortic stenosis, extensive three-vessel coronary artery disease, diabetes, uncontrolled hypertension, obesity, chronic kidney disease, and unstable angina. Left heart catheterization
Left heart catheterization (LHC) is an ambiguous term and sometime clarification is required:
LHC can mean measuring the pressures of the left side of the heart.