Cardiac Assessment Flashcards
(96 cards)
Position of the heart
In mediastinum Left of midline Above diaphragm Between medial/lower borders of lungs 3rd-6th ICS Also called the precordium
Position of heart varies with body build
Tall, slender = vertical and positioned centrally
Shorter = more left and horizontal
Factors affecting heart position
body build, chest configuration and diaphragm level
Dextrocardia
Heart positioned to the right, sometimes rotated or displaced as a mirror image
Situs Inversus
Organs flip-flopped
Pericardium
Tough, double-walled, fibrous sac encasing and protecting the heart
Several milliliters of fluid are present between inner and outer layer for low-friction
Layers of the heart
Epicardium
Myocardium - muscular layer for pumping
Endocardium - innermost layer, lining chambers and covering valves
Anatomy and Physiology of Left Ventricle
Bigger in adult heart
higher pressure in systemic circulation requires greater force of contraction (and more muscle mass) in order for blood to be pumped to body
LV contraction and thrust = apical pulse
Atrioventricular Valves
Tricuspid (3 leaflets)
Mitral or Bicuspid (2 leaflets)
Close on systole
Semilunar Valves
Aortic and Pulmonary (3 cusps)
Open on systole
Close on diastole
What factors influence how much blood volume returns to the heart?
Body activity, physical, and metabolic (exercise and fever)
Systole
Pressure raises in ventricles AV valves close S1 or "lub" intraventricular pressure > aortic/pulmonic pressure SL valves open
Diastole
Ventricle pressure < aortic/pulmonic SL valves close S2 or "dub" A2 is aortic and P2 is pulmonic closure Ventricle < atrial pressure AV valves open
Filling of ventricles = what sound?
S3
Atrial contraction = sometimes what sound?
S4
S2 Splitting
Aortic closes before pulmonic sometimes
A2 before P2
Sounds heard best in area away from the heart because sound is transmitted in the direction of BF
Electrical conductivity pathway
SA wall of RA AV atrial septum (delayed impulse) bundle of His Purkinje fibers in ventricular myocardium Moves from Apex towards the base
ECG records what?
Ions moving in and out of the myocardial membranes
PR interval
delay from initial stimulation of atria to stimulation of ventricle AV node (gatekeeper) responsible for delay NO DELAY = possible backflow/insufficient BF
ST segment
ST elevation is due to possible MI
Ventricular repolarization
U wave
Related to repolarization of purkinje fibers
Also seen in electrolyte abnormalities like severe hypokalemia
QT interval
Onset of ventricular depolarization to repolarization
Heart function in infants
Patent ductus arteriosis (bypass lungs) and foramen ovale (atrial septum hole) close to allow blood flow to lungs (within 24-48 hours)
RV and LV assume pulmonary and systemic circulation
LV mass increases within first year
Heart lies more horizontal and apex higher
Adult heart position reached at 7 years
Indications for Infants
Tiring during feeding Breathing changes Cyanosis Weight gain Knee-chest position Mother's health during pregnancy