Cardiac Bioengineering Flashcards
What wraps the heart?
a protective sheath called the Pericardium
What are the three layers of the heart?
Epicardium - outer layer including connective tissue
Myocardium - the cardiac muscle
Endocardium - endothelium layer
What is the cardiac muscle?
myocardium
only found in heart
contracts to pump blood through heart
appears striated, long cells
short branching cell with one or two large nuclei
cardiac fibers join the cells for cellular networks
free passage of ions
What are the chambers of the heart?
Two atria- receiving chamber
Two ventricles - discharging chamber
How many valves are there?
4 unidirectional valves
What are the atriventricular valves?
between atria and ventricles
tricuspid (right atria-ventricular valve)
bicuspid/mitral valve ( left atria-ventricular valve)
What are the semilunar valves?
between ventricle and artery
pulmonary valve
aortic valve
How are the systems for heart beat?
Sinoatrial Node
Atrioventricular Node
His-Purkinje System
What is the SA node?
sinoatrial node
natural pacemaker
contains specialized innervated cells
produces 60-100 electrical signals per minute
What is the AV node?
atrioventricular node
located in the bridge between the atria and ventricles
electric signals pass from the atria down to the ventricles through the AV node
What is the Purkinje System?
carries electrical signal throughout the ventricles to produced contractions
What are the steps for cardiac conduction?
Pacemaker impulse generation
AV node impulse conduction
AV bundle conduction
Purkinje fiber conduction
What is an electrocardiogram?
ECG/EKG
measures cell potential
measure of cardiac muscle depolarization followed by depolarization
What are the three components of ECG?
P wave: depolarization of atria, pacemaker firing
QRS complex: depolarization of ventricles
T wave: depolarization of ventricles
What are the important segments of the ECG?
PR interval: time electrical impulse takes to travel from SA to AV
ST segment: time in which ventricles are depolarized
QT: ventricle contraction until the heart is ready to fire again
What is a cardiogram?
graph of voltage v time
What is a pacemaker?
electrode device used to imitated a heartbeat when the intrinsic system fails when there is no output or signal is too weak to generate enough
What are the components of the pacemaker?
pulse generator electrode battery sensor leads can be single or dual chamber
What are the types of heart valves?
mechanical: inert and durable
bioprosthetic: animal tissue
What is the silastic ball valve?
mechanical heart valve bulky not suitable for mitral replacement induces hemolysis smaller sizes become stenotic
What is the tilting disc valve?
good hemodynamics excellent durability central laminar flow anticoagulation mandatory (therapy) higher risk of thrombosis
What is the St. Jude medical bileaflet valve?
most common low bulk, light weight superior hemodynamics greater opening area performs well under a range of cardiac pressures
What is the trileaflet?
closer mimic of physiological function
even greater hemodynamics
reduced thombosis
Describe bioprosthetic heart valves.
xenograft
allograft
stented or stentless
scentless: lower post op gradient, greater flow, earlier regression of LVH, implantation is more complex
