A PAC is not indicated in situations where it will provide no diagnostic information that cannot be acquired by less invasive means. For example, while a PAC may be helpful in diagnosing or treating patients with mitral regurgitation or ventricular septal defects following myocardial infarction, echocardiography may be sufficiently diagnostic and may obviate the need for a PAC. The same can be true in cases of cardiac tamponade. The PAC may also be superfluous in situations where it will provide little or no therapeutic guidance. The insertion of a PAC is not necessary if a therapeutic trial of fluid administration restores urine output and blood pressure in a hypovolemic patient who has normal cardiac function. Other contraindications include patients with: cardiac dysrhythmias, implanted pacemakers or defibrillators, pulmonary hypertension, right-sided endocarditis, right-sided intracardiac valvular abnormalities, right-sided prosthetic heart valves, right-sided intracardiac thrombi, or severe hypotension. A PAC should not be inserted if the appropriate equipment is unavailable or if personnel experienced with the insertion and interpretation of the PAC data are not present.19,20