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Cardiology > Formulas > Flashcards

Formulas Flashcards

1
Q

Laplace

A

Wall Stress: Pressure x Radius/ 2x Wall thickness

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2
Q

Cardiac Output

A

SV x HR

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3
Q

Stroke Volume

A

LVEDV-LVESV

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4
Q

LV Stroke Index

A

SV/BSA

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5
Q

LV Cardiac Index

A

CO/BSA

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6
Q

FS

A

(LVd-LVs / LVd) x 100

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7
Q

EF

A

SV/EDV x 100

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8
Q

RV systolic pressure from VSD

A

Systolic BP- 4V2

V is max VSD velocity
(Systolic BP is LVSP in the absence of obstruction)

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9
Q

PA diastolic pressure

A

RA pressure plus 4V2 (V equals PR max at end diastole)

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10
Q

LV systolic pressure

A

Systolic pressure plus 4V2 (V equals AoV max)

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11
Q

LV EDP

A

Diastolic cuff pressure -4V2 (V equals AR max at end diastole)

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12
Q

LA systolic pressure

A

Systolic pressure -4V2 (V equals MR max)

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13
Q

PISA

A

(2 pi r 2) x Val / V max x VTI

Val- aliasing velocity
V max
Peak velocity of stenosis jet
R is PISA radius

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14
Q

Instantaneous flow rate by PISA

A

2 pi r2 X Val X 6

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15
Q

Pressure half time

A

Deceleration time x 0.29

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16
Q

FICK

A 
02 consumption (ml/min) / 
(CaO2 - CvO2) x 10 (for liters per minute)

Or
O2 consumption/
A-VO2 1.36Hgb*10, where A-VO2 is arterial venous saturation difference

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17
Q

O2 content arterial blood

A

CaO2=(1.36 x Hb x SaO2) +0.003 x PaO2

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18
Q

O2 content venous blood

A

CvO2=(1.36 x Hb x SvO2) +0.003 x PvO2

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19
Q

thermodilution CO

A

(Temp Diff) x C /

Area under TDCO curve

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20
Q

Systemic Vascular resistance

A
  1. Measures LV afterload

(Ao mean - RA mean)*80/Qs

(Units are dynes/sec/cm-5)
Qs = systemic cardiac output

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21
Q

MAP

A

(2 x diastolic BP) + Systolic BP/ 3

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22
Q

Hakki valve area calculation

A

CO/

sq rt of peak to peak gradient

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23
Q

Gorlin for aortic valve area

A
  1. Measures valve area

CO (in cc’s) /
(SEP *HR)/44.3 *sq rt mean gradient

SEP- another Flashcard!

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24
Q

SEP (systolic ejection pd)

A

Time semilunar valves open to time they close
Measure @ 100mm/s paper speed
1 sm box 4mm, boxes x HR / paper speed

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25
Q

Peak to Peak

A

P1-P2- gradient

P1 is max LV systolic
P2 is max Ao systolic

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26
Q

Flamm

A

SvO2= 3 (SVC) plus 1(IVC) / 4

27
Q

Qp

A

VO2 / (CpvO2-CpaO2) x 10

VO2 is O2 consumption

28
Q

Qs

A

VO2/ (CaO2-CmvO2) x 10

29
Q

Absolute Shunt

A

Qp-Qs

Pulmonic blood flow-Systemic blood flow

30
Q

% shunt

A

(Qp-Qs) / Qp

31
Q

No shunt

A

PBF = SBF = EBF

32
Q

What is tau?

A

Time constant of isovolumetric relaxation (preload independent)
Highly dependent on accuracy of ventricular pressure measurements

33
Q

Bainbridge reflex

A

Increased HR due to increased CVP

  • increased venous return increases stretch on atria
  • stretch receptors increase B fiber firing
  • modulates autonomics to SA node –>increased HR
34
Q

Poiseuilles law

A

The principle that the volume of homogeneous fluid passing per unit time through a capillary tube is directly proportional to the pressure difference btwn its ends and to the 4th power of its internal radius, and inversely proportional to its length and to the viscosity of fluid

35
Q

Reynolds number

A

Dimensionless quality in fluid mechanics- used to determine the transition from laminar to turbulent flow.

Laminar flow occurs at low Reynolds numbers, where viscous forces are dominant
Turbulent flow is produced at high reynolds numbers, and dominated by inertial forces, chaotic flow instabilities

36
Q

Left to right shunt

A

Qp-Qs

37
Q

Flow ratios- what they mean

A

<1 indicates R–>L shunt
1 indicates no shunt
<1.5 indicates small shunt
>2.0 large shunt–> needs surgical intervention

38
Q

Flow ratio equation (Qp:Qs)

A

Qp/ = (SA O2 - MV O2)/
Qs (PV O2 - PA O2)

MV is mixed venous

39
Q

Anachrotic notch

A

Early notch on arterial pressure wave corresponding to the presystolic rise in pressure (isovolumetric contraction).

-notch occurs earlier and lower down on upstroke with severe SAS-
Slow build up of pressure and long interval btwn flow through narrowed orifice and aortic pressure peak
Venturi effect may contribute
-not

40
Q

Bisferiens pulse

A

Presence of notch in middle of waveform suggests mild stenosis, but depth of notch suggestive of high flow velocity.
May see in diseases with increased volume - PDA, AR, mild AS
- presence is contraindication for valvulotomy in people- by already have significant regurg

41
Q

Dichrotic notch

A

Corresponds to reflected waves from aortic valve closure.

42
Q

Pulses alternans

A

Beat to beat alteration in pulse size and intensity. Left heart failure,poor contractility, tachycardia

43
Q

Pulses paradoxus

A

Exaggerated decline in BP during inspiration (increased neg intrathoracic pressure). Tamponade, constrictive pericarditis, severe lung disease.

44
Q

Decremental conduction

A

Functional block; attenuation of action potential amplitude as it progresses through the AV node and a reduction in its efficacy to excite adjoining cells.
AV nodal cells have slow recovery period and it becomes slower as HR increases.
Prolonged refractory pd also characteristic of nodal cells.

45
Q

Pulmonary vascular resistance

A

(Mean PA pressure) - (PAW) x 80/CI

P

46
Q

L–>R shunt formula

A

PBF-SBF

Or Qp-Qs

47
Q

Bidirectional shunt formula

A

PBF-EBF

Where ebf is effective blood flow, the fraction of mixed venous return to lungs without shunt contamination

48
Q

R–>L shunt formula

A

SBF-EBF

49
Q

Tei index

A

IMP = (IVRT+IVCT) / ET

ET is ejection time

50
Q

Continuity equation

A

Flow across LVOT equals flow across aortic valve

SV/ TVI (of AoV)

51
Q

Mitral valve area from PHT

A

MVA = 220/PHT

52
Q

Acoustic impedance

A

Resistance to flow of sound through medium (density X speed)

Bone shadow is high acoustic impedance

53
Q

Reflection

A

Sound turned back at the boundary of a medium

54
Q

Refraction

A

Change in direction of sound from one medium to another

55
Q

Scatter

A

Structures that are small and irregular scatter sound in all directions- offered info about tissue character

56
Q

Attenuation

A

Loss of energy from traveling through medium
(high freq more than low freq)
Large degree of attenuation = less transmission

57
Q

Tissue harmonic imaging

A

U/S transmitted at one frequency and returned at higher frequency
Good for poor acoustic windows

58
Q

Pulse repetition frequency

A

Number of pulses per seconds
Should be 2X sample depth
Nyquist the limit is 1/2 PRF

59
Q

Nyquist limit

A

1/2 PRF.
Signal ambiguity of limit exceeded
Aliasing= signal ambiguity

60
Q

SV

A

LVOT area x LVOT TVI

61
Q

Regurgitant volume (from PISA)

A

EROA (from PISA) x MR TVI

62
Q

Dp/dt

A

32mmHg/time (sec)

63
Q

Qp:Qs

A

(Ao sat-MV sat) / (PV sat-PA sat)

64
Q

Cardiac output

A

(Edv-esv)*hr

Cardiology (4 decks)

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