Cardiac physiology and murmurs Flashcards
Describe the pathway of blood circulation
starting at VC
DeO2 blood enters via IVC/SVC
Enters right atrium
^ pressure opens tricuspid valve -> right ventricle
^ pressure opens pulmonary valve -> pulmonary arteries -> lungs
O2 enters via pulmonary veins
enters left atrium
^ pressure opens mitral valve -> left ventricle
^ pressure opens aortic valve -> aorta -> body
What is the Endocardium
Innermost layer of the heart wall
lines heart valves and cavities
regulates heart contractions
What is the Myocardium
Middle layer of the heart wall,
composed of cardiac muscle fibers.
Causes heart contractions
What is the Epicardium
Outermost layer of the heart wall aka visceral pericardium
Thin layer of connective tissue and fat that serves as an additional layer of protection
What are the pectinate muscles
muscular ridges located in the atria of the heart, specifically in the right atrium and auricle. They increase the surface area.
What are the Chordae tendineae
Cord-like tendons that connect the papillary muscles to the tricuspid valve and mitral valve in the heart.Prevent the valve from prolapsing during the ventricular systole.
What are the Trabeculae carneae
Muscular columns in the right/left ventricles.
Provide additional ventricular valve support
Help maintain the SV + CO
What are Papillary muscles
Located in the ventricles.
Attach to AV valves cusps via chordae tendineae
Contract to prevent inversion/prolapse during systole (or ventricular contraction)
What is the interventricular septum
Muscular wall that separates the ventricles of the heart. Wall of cardiac tissue that comprises muscular and membranous tissue
Components of systole
Isovolumetric contraction
Rapid ejection
Reduced ejection
Components of diastole
Isovolumetric relaxation
Rapid filling
Reduced filling
Cardiac output eq
CO= HR x SV
vol of blood pumped in one min
Stroke volume eq
SV = EDV - ESV
Mean arterial pressure eq
MAP = DP + 1/3(SP - DP)
What happens during isovolumetric contraction
Wave of ventricular depolarisation - QRS complex
AV valves close -> S1 sound
no change in volume as pressure hasn’t exceeded aorta yet
What happens during isovolumetric relaxation
Start of diastole
SL valves close -> S2 sound
no vol change as atrial pressure has not exceeded ventricles yet.
What occurs during rapid ejection
SL valves open
dec. ventricular volume but pressure is still greater than aorta
What occurs during reduced ejection
T wave - repolarised ventricles
ventricular vol decreases more slowly
What occurs during rapid filling
isoelectric ECG
AV open, ^ vol in ventricles
What occurs during reduced filling
^ ventricular vol slows
No atrial contraction
What occurs during atrial systole
P wave - atrial excitation
atria contract to ^ ventricular volume
What causes the S1 heart sound
AV valves closing during start of ventricular contraction
What causes the S2 heart sound
SL valves closing during isovolumetric relaxation
What causes the S3 heart sound
Rapid filling and expansion of ventricles
During early diastole (rapid filling)
Pathology - congestive heart failure
What causes the S4 heart sound
Forced atrial contractions pushing blood into stiff ventricles
During late diastole (atrial systole)
Pathology - atrial hypertrophy/stiff ventricles (HTN, Cardiomyopathy, ischaemia)
What is a heart murmur
Caused by turbulent flow through valves
whooshing/rasping heard during heartbeat
Types of murmurs
Systolic murmur
Diastolic murmur
Continuous murmur
When does a systolic murmur occur
Heart pumping blood to the rest of the body
When does a diastolic murmur occur
Heart relaxes btw beats to fill with blood
When does a continuous murmur occur
Throughout the heartbeat
Murmur heard in Aortic stenosis
Ejection systolic murmur
Murmur heard in Aortic regurg
Early diastolic murmur
Murmur heard in Mitral stenosis
Mid diastolic murmur
Murmur heard in Mitral regurg
Pansystolic murmur
Murmur heard in patent ductus arteriosus
continuous “machinery” murmur
What is aortic stenosis
Narrow, inflexible aortic valve
Blood enters through small opening in systole
difficult entry to aorta
What is aortic regurg
Valve leaflets floppy, improper valve closure
Leak blood into ventricle during diastole
What is Mitral stenosis
Narrow, inflexible mitral valve
Difficult for blood to travel atria -> ventricle during diastole (mid)
What is mitral regurg
Floppy mitral valve leaflets cause backflow of blood during systole
What is a patent ductus arteriosus
Hole in the heart btw Aorta and pulmonary artery
Mixing of blood, free flow btw lungs, aorta and pulmonary artery.
