Cardio Physiology Flashcards by Rachel Longwell

What causes hs1 and 2?

1- closure of the AV valves

2- closure of the SL valves

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Why does HS2 have a physiological split

Pulmonary valve always closes slightly after the aortic

Exaggerated in inspiration as increased blood to the RA

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What causes a fixed split S2

ASD

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What causes a widened split S2 and why?

Delayed pulmonary valve closure
RBBB
HOCM
Pulm stenosis

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What causes a pathological split S2

Aortic closing after the pulmonary
LBBB
Aortic stenosis

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What causes a single S2

Pulm HTN
Truncus, pulm or aortic atresia
TOF, TGA, univentricular circ

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What are the normal sats and pressures of the right heart-
RA
RV
Pulm a

RA-75% 5mmhg
RV- 75% 25/0mmhg
PA- 75%- 25/10

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How do you calculate mixed venous sats

3xsvc+1xivc/4

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What are the normal sats and pressure values for the L heart

LA-97% 5-10mmhg
LV-100/10 97%
Aorta- 97% 100/70

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How do you calculate qp and Qs

What does Qs equate to

120/(pulm v- pulm a sats) hb x1.36
120/(aorta-Mv sats) x hb x1.36

Cardiac output

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What is normal qp:Qs
What will it be in a right to left shunt
What will
It be in a left to right shunt

1
<1
>1

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How do you calculate pulmonary vascular resistance

What is the normal value

Pa-la sats over qp

2, high is >6

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What level is the shunt in ASD
is it volume or pressure related? Why?
What controls the degree and magnitude of the shunt

Arterial
Volume- occurs in diastole
Ventricular elasticity (compliance)

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What level is the shunt in VSD
Is it volume or pressure related?
What controls the degree and magnitude of the shunt in a small or large lesion

Ventricular
Pressure related- increased left pressures
Small- pressure gradient
Large- pulmonary and systemic compliance

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Left to right shunts- what is eisenmengers syndrome and why does it occur

Reversal to a right to left shunt over time- increased pulm pressure to the point where right heart pressure higher than left

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Give 5 right to left shunts

What is the cardinal feature

Cyanosis

Truncus, TGA, tricuspid atresia, TOF, TAPVD

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What are 2 physiological mechanisms behind cyanosis

Reduced oxygenation

Increased tissue usage

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What are the 5 phases of the cardiac cycle

In which stages are the heart sounds
In which phase is the p wave, QRS complex and t wave

Isovolumetric ventricular contraction 
Rapid ejection 
Reduced ejection 
Isovolumetric ventricular relaxation 
Ventricular filling

Isovolumetric contraction- HS1
Isovolumetric relaxation- HS2
P wave- ventricular filling 
QRS- isovolumetric contraction
T wave- reduces ejection

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At what developmental point can the fetal heart circulate blood?
When do AV valves form?

3 weeks

6 weeks

Outline the anatomy of the fetal circulation

Placenta sends oxygenated blood to the umbilical vein.
Shunts through the liver via the porta hepatis to the hepatic vein which attaches to the ivc
1/3 goes across the PFO (right to left shunt)
2/3 goes to the pulm artery
Highest oxygenated blood to the brain and coronaries
90% of blood across pda
Only 15%through the lungs

What happens after birth to alter fetal back to normal circulation

Placenta is removed so systemic vascular resistance is raised. Porta hepatis closes
Take a breath, pulm vascular resistance falls, reversal of shunt and closure of PFO
o2 is sensed In the aorta and prostaglandin is released which causes the PDA to constrict

Why does the PDA not close in premature babies ( 2 reasons)

Smooth muscle hasn’t learned to constrict with increased o2 levels
High levels of PGE2

Why are premature babies more likely to have heart failure with a PDA

Smooth muscle isn’t developed as well
Sharp fall in PVR
large L to right shunt

Timing of PDA closure:
Physiological
Anatomical

10-15 hrs

2-3 weeks

Outline the pattern of electrolyte movement in the cardiac action potential

``` Resting potential -90 Na rushes in- rapid increase to positive K starts to leave- becomes more negative Calcium enters- plateaus- slow channels K leaves again and ca channels close- returns to negative ```

How do you calculate cardiac output

HR x SV

How do you calculate stroke volume?

End systolic volume- end diastolic

How do you calculate blood pressure

Cardiac output x SVR

How do you calculate pulse pressure

Systolic BP- diastolic BP

How do you calculate MAP

Diastolic + 1/3 pulse pressure

What does Bernoulli’s equation calculate?

Change in pressure across a shunt or valve

What is the equation used in a simple Bernoulli calculation

Change in pressure=4(distal velocity squared)

What is the difference between ejection fraction and fractional shortening?

Ejection fraction=percentage pumped out with each contraction of systole Fractional shortening=how much systole cuts into the end diastolic volume

How do you calculate ejection fraction? | What is the normal value?

ESV-EDV/ESV | 60%

How do you calculate fractional shortening? | What is the normal value?

EDD-ESV/EDD | 30%

What is seen on ECG with right atrial and left atrial hypertrophy

Right- tall tented p waves | Left-bifid p waves (p mitrale)

When are t waves upright

First week of life. After adolescence

Axis What is the mnemonic to remember a right and left axis deviation What will a superior axis look like

Look at leads 1 and AVF Right- right for each other- pointing towards Left- left each other- pointing away Superior- both point down

What is the easy criteria for RVH

RAD Upright t waves in v1 Tall R in v1 Deep S in v6

What is the easy criteria for LVH

Tall r in v6, deep S in v1

What do you seen in biventricular hypertrophy

Both and right criteria positive | Bibentricular forces v3-6

``` ECG and electrolytes What do you see in: Hyperkalaemia Hypokalaemia Hypercalcaemia Hypocalcaemia Hypomagnesaemia ``` Hypothermia?

``` HyperK- tall tented t waves and widened QRS HypoK- u waves HyperCa- short QT HypoCa- long QT HypoMG- long QT ``` Long QT

What is the main cause of systole in pacemaker cells

Rapid ca influx- stored in the sarcoplasmic reticulum

Which embryonic structure is the heart made from When do the 2 tubes fuse When does looping begin

Mesoderm 20 days 28 days

What makes the left and right ventricles When does looping occur When do the 4 chambers form? When do the valves form?

``` Left- primative ventricle Right- bulbous cordis 24 days 28 days 8 weeks ```