Anesthesia Student Survival Guide.pdf - Index of

266 ● AnesthesiA student survivAl Guide
Table 17.1 Coronary artery supply.
Source Branch #1 Branch #2 Supply
left main
Circumflex Obtuse marginal
branches
left ventricle lateral & posterior walls
left anterior
septal branches Majority of interventricular septum
descending (lAd)
diagonal branches left ventricle surface
right main Acute marginal branches right ventricle
Av nodal & sA nodal Av & sA nodes
Posterior descending inferior & posterior ventricles
(LAD) artery and the circumflex artery. These provide blood supply to the left
ventricle and the anterior 2/3 of the interventricular septum. The right main
coronary artery gives rise to the posterior descending artery (PDA) and other
branches which supply the right ventricle and posterior 1/3 of the interventricular
septum. The origin of the PDA (right coronary versus circumflex artery)
determines whether the coronary circulation is right or left dominant, respectively.
Perfusion of the left sided coronary arteries occurs during diastole only.
The venous supply from the heart follows the arterial supply and the
coronary veins drain into the coronary sinus which then drains into the right
atrium. Thebesian veins, which connect directly to the left ventricular cavity
also provide a route for venous drainage.
There are four heart valves that promote unidirectional flow (see Fig. 17.1).
They open and close based on pressure changes that occur on either side of
the valve. The heart’s atrioventricular valve on the left side is the mitral valve
(between the left atrium and ventricle), which has two leaflets: anterior and
posterior. The atrioventricular valve that connects the right atrium and right
ventricle is the tricuspid valve, which has three leaflets: anterior, posterior, and
septal. The left ventricle pumps blood into the aorta via the aortic valve. The right
ventricle pumps blood into the pulmonary artery via the pulmonary or pulmonic
valve. Both of these valves are semilunar valves and have three cusps.
The cardiac conduction system is comprised of autorhythmic cells that
initiate and conduct action potentials. In a normal heart, the sinoatrial (SA)
node is the heart’s pacemaker. After an impulse is generated here, it conducts
to the atrioventicular (AV) node, where it splits into the Bundle of His
down the left bundle branch and right bundle branch. Eventually, the ventricular
muscle is innervated when the impulse reaches the Purkinje fibers.