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Cardiology > Formulas > Flashcards

Formulas Flashcards

(64 cards)

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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
Peak to Peak
P1-P2- gradient P1 is max LV systolic P2 is max Ao systolic
26
Flamm
SvO2= 3 (SVC) plus 1(IVC) / 4
27
Qp
VO2 / (CpvO2-CpaO2) x 10 VO2 is O2 consumption
28
Qs
VO2/ (CaO2-CmvO2) x 10
29
Absolute Shunt
Qp-Qs | Pulmonic blood flow-Systemic blood flow
30
% shunt
(Qp-Qs) / Qp
31
No shunt
PBF = SBF = EBF
32
What is tau?
Time constant of isovolumetric relaxation (preload independent) Highly dependent on accuracy of ventricular pressure measurements
33
Bainbridge reflex
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
Poiseuilles law
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
Reynolds number
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
Left to right shunt
Qp-Qs
37
Flow ratios- what they mean
<1 indicates R-->L shunt 1 indicates no shunt <1.5 indicates small shunt >2.0 large shunt--> needs surgical intervention
38
Flow ratio equation (Qp:Qs)
Qp/ = (SA O2 - MV O2)/ Qs (PV O2 - PA O2) MV is mixed venous
39
Anachrotic notch
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
Bisferiens pulse
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
Dichrotic notch
Corresponds to reflected waves from aortic valve closure.
42
Pulses alternans
Beat to beat alteration in pulse size and intensity. Left heart failure,poor contractility, tachycardia
43
Pulses paradoxus
Exaggerated decline in BP during inspiration (increased neg intrathoracic pressure). Tamponade, constrictive pericarditis, severe lung disease.
44
Decremental conduction
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
Pulmonary vascular resistance
(Mean PA pressure) - (PAW) x 80/CI P
46
L-->R shunt formula
PBF-SBF Or Qp-Qs
47
Bidirectional shunt formula
PBF-EBF Where ebf is effective blood flow, the fraction of mixed venous return to lungs without shunt contamination
48
R-->L shunt formula
SBF-EBF
49
Tei index
IMP = (IVRT+IVCT) / ET ET is ejection time
50
Continuity equation
Flow across LVOT equals flow across aortic valve SV/ TVI (of AoV)
51
Mitral valve area from PHT
MVA = 220/PHT
52
Acoustic impedance
Resistance to flow of sound through medium (density X speed) | Bone shadow is high acoustic impedance
53
Reflection
Sound turned back at the boundary of a medium
54
Refraction
Change in direction of sound from one medium to another
55
Scatter
Structures that are small and irregular scatter sound in all directions- offered info about tissue character
56
Attenuation
Loss of energy from traveling through medium (high freq more than low freq) Large degree of attenuation = less transmission
57
Tissue harmonic imaging
U/S transmitted at one frequency and returned at higher frequency Good for poor acoustic windows
58
Pulse repetition frequency
Number of pulses per seconds Should be 2X sample depth Nyquist the limit is 1/2 PRF
59
Nyquist limit
1/2 PRF. Signal ambiguity of limit exceeded Aliasing= signal ambiguity
60
SV
LVOT area x LVOT TVI
61
Regurgitant volume (from PISA)
EROA (from PISA) x MR TVI
62
Dp/dt
32mmHg/time (sec)
63
Qp:Qs
(Ao sat-MV sat) / (PV sat-PA sat)
64
Cardiac output
(Edv-esv)*hr

Cardiology (4 decks)

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