Cardiac Cycle

Question 1

When the heart walls thicken during contraction, what does that mean? (not pathological)

Answer 1

thicken bc heart shortening and sarcomeres closer together, chambers getting smaller and forcing blood out through aorta

Question 2

Why are recordings of venous pulse usually on the right side?

Answer 2

venous pulse is the acv wave .. recorded on R side bc catheter goes in groin, IV, and then to side of R atrium.
R atrial pressure = venous pressure. (no valve between R atria and IVC)
no valve, also low pressure side of body..the venous side of body) don’t put catheters in arterial system..high pressure system could break off clot,

Question 3

What happens right before the p wave?

Answer 3

sinus node is activated right before the p wave, pressure is falling in arterial system from previous cycle, still in diastole from previous cycle.
so sinus node fires, conducts through atria muscle, and thats the p wave.

Question 4

What is diastasis?

Answer 4

its the second part of filling. (reduced part)

Question 5

Discuss atrial contraction.

Answer 5

impulse spreads across atria, when atria contracts it pumps a little blood through mitral valve into ventricle (that’s atrial systole which occurs during ventricle diastole) …atria only contribute about 5 percent or less under resting conditions to L ventricle - does become more important under exercise.
when vigorously exercising, atrial contribution is more significant to L ventricular filling - more like 10 percent

Question 6

Why might someone not experience any symptoms of a fib under resting conditions? When might you experience symptoms?

Answer 6

no symptoms bc atria don’t contribute significantly to resting filling. under resting conditions affect Cardiac output. but exercise conditions it does. by reducing filling of L ventricle, you’re reducing preload, which is one of things in L-tension rel, that det. strength of contraction of L ventricle and thus SV. so walking quickly in airport or climb stairs- these people will get tired bc their cardiac output compromised a little bit.

Question 7

What are the 3 phases of diastole?

Answer 7

rapid filling phase, slow filling phase, atrial systole/atrial kick.

Question 8

Discuss the a wave in the venous pulse graph.

Answer 8

When R atria contracts it does generate an increase in pressure. (a wave)

Question 9

What physical indication might you see when examining a patient in heart failure?

Answer 9

venous pulse recording is same venous pulse you look at in patients on neck (the jugular feeds right into SVC)…imp. in heart failure… bulging venous pulse in neck bc heart not able to empty.

Question 10

Describe the impulse pathway.

Answer 10

impulse has already entered the AV node by the time get to p wave. impulse is sitting in AV node transferred from atria to ventricle.. slow conduction. now impulse enters His-P system. coming right into ventricle, activated QRS,

Question 11

What is the first heart sound? What does it result from?

Answer 11

closure of mitral valve (closes as a result of passive pressure gradients, atria has just emptied blood into ventricle so pressure in atria is v low and in ventricle its high and that pressure gradients between the atrial and ventricular chambers closes the valve

not due to contraction of ventricle or activation of ventricle electrically. valve not electrically excitable- its a piece of connective tissue. doesn’t carry electrical impulses. just flappy valve. thin. easily open and close in response to pressure gradients. they’re completely passive. activation of chords tendenae/papillary muscle holding onto it preventing it from prolapsing in wrong direction when pressure is developed in ventricle

Question 12

What causes the c wave in the venous pulse graph?

Answer 12

AP conduction around heart- QRS, that activates all cells within 100 ms. and those cells bring up pressure quite dramatically. at same time, this increase in pressure, see c wave. turns increase in pressure in ventricle is causing the mitral valve to bulge back - doesn’t open but pressure generated during isovolumic contraction is pretty high and it pushes the valve back and sends a pressure wave back into atria and into venous system.

Question 13

Describe the isovolumic contraction phase.

Answer 13

isovolumic contraction - volume of ventricle is iso, not changing. mitral valve is closed and aortic valve is closed and ventricle is electrically activated to try to compress imcompressable fluid, so pressure goes up v high, requires ATP- a lot of it. this uses more energy than actual ejection of blood. isometric phase v energy consuming. increase in pressure occurs and is as close as heart gets to isometric contraction. shape of heart does change and some cells are stretching sarcomeres and others contraction but if you measure all, no change over time. shape may change but no change in volume. heart has to generate enough tension to overcome pressure on other side of valve, thats afterload, load on muscle after contraction starts

Question 14

When does the aortic valve open?

Answer 14

as pressure increases and after load decreasing from previous cycle, will exceed it and open aortic valve at that point. explosive opening of aortic valve and blood ejected.

Question 15

What are the two phases following isovolumic contraction?

Answer 15

after aortic valve opens bc of pressure in ventricle exceeding arterial pressure… rapid ejection- most volume is lost, slow ejection -

Question 16

What is happening during ventricular systole in the atria?

Answer 16

blood returning to atria from venous return …blood back from SVC and IVC filling atrial chamber and that pressure goes up as result of filling of atria on both sides of heart. thats atrial diastole which is occurring during ventricular systole. cant have systole in both chambers at same time.

Question 17

Why does ejection slow down?

Answer 17

one reason is that heart increasing pressure downstream from ventricle (arterial pressure) increasing its own afterload.

Question 18

What happens to the amount of shortening of ventricular muscle as afterload increases?

Answer 18

it decreases. after load is high, so muscle has already shortened, at shorter muscle length and increased after load can generate less force. highest velocity of shortening is initial and later on is reduced (due to increase in after load and reduction in length of muscle) this phase is isotonic like contraction, but not pure isotonic. isotonic-like bc muscle shortening..isotonic contraction that has larger and larger after load in heart. bc it creates its own afterload. if arterial pressure at this point higher than ventricular pressure, how does blood move forward? bc of inertia, velocity of blood flow has energy to it, not strictly to pressure gradient, really energy gradient, part of energy is inertia, movement (kinetic and potential =pressure) so energy gradient is still forward.

Question 19

What is happening during the t wave?

Answer 19

repolarization of the ventricle. Ca taken back into SR. pressure in ventricle is falling, pressure in arterial system falling as well, has ejected blood, ejection fraction of ventricle is about 60 percent in efficient and healthy heart.

Question 20

Discuss the fraction of blood ejected with one stroke.

Answer 20

should have fraction of blood ejected with one stroke about 60 percent. leaving behind about 40 percent=blood left behind is end systolic volume. diff between end diastolic volume and end systolic volume= diff between when heart filled with blood and what’s left in heart=what was ejected. so that’s stroke volume.

Question 21

As heart relaxes, after reduced ejection, what happens?

Answer 21

v low pressure in ventricle but pressure in arterial system quite high. in next phase what separates them? closure of aortic valve. as pressure in ventricle drops, at that moment pressure in ventricle lower than pressure in arterial system and that passively closes the aortic valve and causes the second heart sound. 2nd heart sound, closure of aortic and pulmonary valves, due to pressure has fallen below pressure in arterial system and that passively closes aortic valve. this decline in pressure is isovolumic relaxation

Question 22

What is happening in isovolumic relaxation?

Answer 22

(no change in volume bc both valves closed) pressure is falling, both valves closed, so pressure in the ventricle is falling and pressure in arterial system not falling bc aortic valve closed.

Question 23

What causes the notch in the pressure graph after the aortic valve closes?

Answer 23

aortic valve snaps closed then what happens to cause increase in arterial pressure? it bounces up… the aorta is most elastic tissue in arterial system, so what happens in normal heart is that blood ejected into arterial system (large volume) compliant arterial system, elastin in arterial wall allows arterial wall to distend bc its compliant. vessel extends, aortic valve closes and recoils, like rubber band, so that recoil is like secondary pump, blows up arterial pressure.

Question 24

What would happen if the aortic valve did not recoil back after it closed?

Answer 24

if you didn’t have that… aortic valve closes, now diastolic pressure drops. not better bc now heart has to bring pressure from lower value all way back to 120, more work of heart. so low compliance of aorta- its independent risk factor for congestive heart failure. its an after load on heart…more difficult for heart to pump against fibrotic/low compliant aorta. important.

Question 25

What happens after the aortic valve closes?

Answer 25

muscle recoils causes notch, ventricular pressure falls to zero. falls until pressure in ventricle falls below the pressure below that in arterial (atrial?) system which is filling w blood, so atrial pressure now higher than ventricular pressure. as soon as they cross mitral valve pops open passively bc pressure gradient. completely passive. passive gradient, pressure in atria higher than pressure in ventricle and initial phase of filling is rapid filling bc large pressure gradient between atria and ventricle. outflow, most gone during rapid ejection phase, at filling phase- ventricular volume is right here, where mitral valve opens

Question 26

Discuss the two phases after isovolumic relaxation.

Answer 26

most of volume, 60-70 percent increase in rapid filling phase. majority of filling of heart during rapid filling then slows down bc pressure gradient is reduced (more blood in ventricle, pressure going up) and pressure in atria going down, similar to e/o so pressure gradient lost and 2nd phase of filling is slow or reduced filling phase. due to decrease in pressure gradient.

Question 27

Where would premature beats occur?

Answer 27

during filling phases. during electrical diastole. premature beat occurs…follow it down… about 60 or 70 percent of blood already in ventricle, but still about 30 percent short so preload is lower, but lots in there. arterial pressure at that moment is really high compared to before so after load during premature beats is quite high which makes it v difficult for low contractility of premature beat to open the aortic valve. so the earlier premature beat occurs, higher the after load and lower the preload. premature beat late in diastole arterial pressure lower and filled up maybe 90 percent in ventricle and maybe get ejection there…Ca recovered more if longer ventricle.

Question 28

Describe diastasis.

Answer 28

2nd phase of filling/ diastasis, reduced filling phase. blood trickling in, valve wide open during rapid filling then in next phase the mitral valve still open but trickling in at that point. last phase of diastole is atrial systole and blood being ejected from mitral valve again actively … 90 percent of filling of ventricle due to passive pressure gradient between atria and ventricle

Question 29

What happens if someone has mitral stenosis?

Answer 29

blood flows across the mitral valve during diastole. if it doesn’t open well then nothing is allowing blood to flow into ventricle (its passive, not active, flowing downstream)
so if something preventing blood flow then serious problem. people with mitral stenosis heart not filling w blood normally, atrial contraction becomes such more important bc thats the only active filling you have left

Question 30

In congestive heart failure there’s lots of blood left in heart, what will that do to pressure gradient for blood to flow into the heart?

Answer 30

if you have large end systolic volume (heart congested w blood), what will that do to pressure gradient ? ejected 10 percent, leaving behind 90 percent of blood in ventricle. will slow down filling of ventricle quite a bit bc no gradient. passive gradient has important implications.
leaving behind most blood, gradient for blood flow during diastole reduced and not filling normally relying on atrial kick… atrial systole to fill ventricle

Question 31

What happens if someone has a-fib and congestive heart failure?

Answer 31

leaving behind most blood, gradient for blood flow during diastole reduced and not filling normally relying on atrial kick… atrial systole to fill ventricle, if go into a-fib very little diastole filling, then shortness of breath

Question 32

What causes the v wave of the venous pulse graph?

Answer 32

v wave - when mitral valve opens, atria empty and that causes v wave. filling and emptying of atria- v wave

Question 33

What would happen to the venous pulse graph if someone had tricuspid stenosis?

Answer 33

acv wave- a wave.. a wave due to atrial contraction, pumping blood through tricuspid and mitral valves … what happens if tricuspid stenosis (doesn’t open normally) more diff for blood to enter atria to ventricle… what happens to pressure in atria? goes up dramatically and see large a wave (give away for tricuspid stensois) used diagnostically to look at normal cardiac function.

Question 34

What are the 3rd and 4th heart sounds?

Answer 34

they are turbulence. third heart sound usually pathological- usually dilated cardiomyopathy where heart dialated abnormally …when blood rushes in at rapid filling, that rapid filling causes turbulence and hear that as 3rd heart sound. called gallop when hear 1st, 2nd and 3rd heart sounds.

4th heart sound happens just after p wave, its caused by turbulence generated by atrial contraction. in some people in normal people can hear 4th heart sound. 4th caused by atrial systole and 3rd by rapid filling both by turbulent blood flow.

in general 3rd pathological and 4th may or may not be pathological and depends on circumstances.

normal heart- only see 1st (slamming of mitral valve) and second (slamming of semilunar valve) 3rd-rapid filling of ventricle (dont hear that often, if not athlete or pregnant could be concerned bc could be bc of dilation of heart) … 4th almost always concerning. is due to stiff ventricles. is atrial kick against stiff ventricles-ventricles not as compliant as they should be and atirum will compensate by hypertrophy and getting stronger to use more force to kick in…

Question 35

What is a murmur?

Answer 35

can be due to turbulent blood flow, due to blood too narrow, stenosis or when blood leaks… blood can go back from high pressure side to low pressure side…

Question 36

What happens in mitral regurgitation? Aortic stenosis? How might you tell them apart?

Answer 36

mitral regurgitation- when ventricle contracts blood squirting back across mitral valve- leaky…happens during systole. incompetent valve

aortic stenosis- aortic valve narrow maybe bc valve leaflets not opening well. also happens during systole.

stenosis from regurgitation? both whooshing sound during systole. how do tell apart ? clues besides presence or absence of sounds… feel around where might come from aortic valve vs mitral valve.
aortic stenosis- loudest as blood goes from aorta. mitral regurgitation more of a steady sound.
mitral regurgitation- during systole, lower freq. sound
aortic regurgitiation- during systole, (shorter waves and high pitch sound)

aortic stenosis -narrowing of aortic valve. during systole get sound as blood whooshing past. will be after heart sound 1. between lub and dub hear whooshing. stenosis is only loud when blood rushing quickly.. high pitch bc super high pressure. blood squeeking through at high pitch.

Question 37

How do you measure left arterial pressure? (Want to know bc of mitral stenosis…)

Answer 37

if mitral valve stenosed and unable to pump blood easily from L atrium to L ventricle then L atrial pressure elevated…this is pressure concerned w pulmonary edema cause that pressure from L atria backing up into lungs. pulmonary wedge- catheter with balloon at end… put catheter in branch of pulmonary artery, inflate the balloon and cut off pressure from the heart. if u cut off pressure from heart then no longer pressure downstream and pressure at this point equilibrates with pressure in L atrium and can measure pressure in L atrium by using pulmonary wedge. catheter that goes into R side of heart to branch of pulmonary artery, inflate balloon, cuts off pressure downstream transducer… pressure downstream from balloon equilibrates with pressure in L atrium. thats why pulmonary wedge same as L atrial pressure. now can measure non invasively w echo. memorize the averages but fit into cardiac cycle and were these pressures are coming from and why.

Question 38

Why does a stenosis cause turbulant blood flow?

Answer 38

if you narrow a valve, reducing cross sectional area of the valve. what happens? increases velocity coming out, shoots up more forcibly and by narrowing cross sectional valve force fluid through narrow opening and that creates turbulent flow which causes sound.. stenosis is narrowing of valve

Question 39

What are the causes and mechanisms of systolic murmur?

Answer 39

creating stenosis in brachial artery. stenosis is general term for narrowing… if you narrow a valve, reducing cross sectional area of the valve. increases velocity coming out, shoots up more forcibly and by narrowing cross sectional valve force fluid through narrow opening and that creates turbulent flow which causes sound.. stenosis is narrowing of valve. if mitral valve didn’t close then during ventricle systole blood would squirt back through mitral valve in retrograde direction-causes murmor. when valve incompetent, opens a little bit and blood flows back. infarction of papillary muscle doesn’t hold onto valve and now bc of pressure during systole it flops back a little bit and have blood squirting back in retrograde direction.

when does systolic murmur occur? during ventricular systole. which way does blood normally go? out through aortic and pulmonic valve on each side of heart? get systolic murmur… if just ejecting into pulmonary or aortic, get stenosis of aortic or pulmonary valve. if aortic stenosis valve not flopping open … (that would be no resistance to blood flow) get stenosis from infection/inflammatory reaction where valve becomes fibrotic. rheumatic fiber- antigen antibody reaction on mitral valve causing mitral stenosis..valve fibrotic, doesn’t flap open, has a hard time opening, becomes stiff, if you have aortic stenosis - have more rapid velocity of blood flow through aortic valve and causes turbulence and hear systolic murmor. can also get systolic murmor… (stenosis in outflow tract is 1st way) also retrograde blood flow back through atria on R or L side by mitral or triscuspid valve and that would be caused by incompetent mitral or tricuspid valve. if mitral valve doesn’t close normally blood can flow backward… turbulent blood flow through narrowed valve.

Question 40

What causes a diastolic murmur?

Answer 40

turbulent blood flow across valve during diastole. normally crosses mitral and tricuspid valve during diastolic filling, normal blood flow across mitral valve so if stenosis of mitral or tricuspid then have diastolic murmur. aortic or pulmonary insufficiency when pulmonary or aortic valve closed (beginning of diastole for heart) then blood flowing from arterial system back into ventricle through insufficient aortic or pulmonary valve…