Cardiac blood pressures (measured via Swan-Ganz catheterization)
Right atrium: < 5 mm Hg
Right ventricle (pulmonary artery pressure): 25/5 mm Hg
During systole, pressures in the right ventricle are much lower than in the left ventricle (only ~25 mm Hg compared to ~120 mm Hg). As a result, coronary perfusion pressure is able to overcome right ventricular wall pressure throughout the cardiac cycle, leading to relatively constant blood flow to the right ventricular myocardium.
Left atrium (pulmonary capillary wedge pressure): < 12 mm Hg (higher than left ventricular pressure in mitral stenosis)
Left ventricle: 130/10 mm Hg
Coronary perfusion pressure
The driving pressure that forces blood into the coronary arteries during diastole
Calculated as the difference in pressure between the aorta and left ventricle during diastole
Cardiac Conduction System
Component
Location
Intrinsic Rate (bpm)
Conduction Velocity (m/s)
SA Node
Upper wall of the right atrium at the junction with the SVC.
60-100 (Primary Pacemaker)
~0.5
Atrial Myocardium
Spreads from SA node across both atria.
N/A
~1.0
AV Node
Interatrial septum, near the opening of the coronary sinus.
40-60 (Secondary Pacemaker)
~0.05 (Slowest)
Bundle of His
Continuation of the AV node; travels through the interventricular septum.
40-60
~2.0
Bundle Branches
Right and Left branches within the interventricular septum.
20-40
~2.0
Purkinje Fibers
Subendocardial surface of the ventricular walls.
~20-40 (Tertiary Pacemaker)
~4.0 (Fastest)
Ventricular Myocardium
Spreads from Purkinje fibers throughout the ventricles.
