Initially, pressures are measured in the aorta, right heart, and left heart. Right heart pressures include pulmonary capillary wedge pressure, pulmonary artery pressures, right ventricular pressures, and right atrial pressure. Left heart pressures are the left ventricular systolic, early diastolic, and end-diastolic pressures. Pressure measurement is followed by determination of cardiac output. Contrast opacification of the left ventricular chamber (left ventricular cineangiography) and other chambers if clinically indicated is also included‚ e.g., contrast opacification of the left atrium in the assessment of an atrial septal defect. Selective angiography of the coronary arteries follows.
How is cardiac output measured?
Cardiac output is commonly measured by dilutional techniques (e.g., thermodilution) or by the Fick method. In the Fick method, cardiac output (CO) = oxygen consumption (VO,)/ arteriovenous oxygen difference (AV02A). Oxygen consumption is measured directly by a mask that fits over the patient’s mouth or face, and blood is sampled from the pulmonary artery and femoral artery to compute AV02A.
What are the normal values for intracardiac chamber pressures in the human heart?
Recalling this information is made easy by applying the rule of fives.‚ In this rule, all pressures are estimated as multiples of five. The right atrial pressure (central venous pressure) is normally -5 mmHg. The right ventricular systolic pressure is -25 mmHg with an end-diastolic pressure of -5 mmHg. The left atrial pressure (estimated by the pulmonary capillary wedge pressure) is -10 mmHg. The left ventricular systolic pressure is normally -125 mmHg with a left ventricular end-diastolic pressure of 10 mmHg.