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M2016 > Physics > Flashcards

Physics Flashcards

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1
Q

Nyquist limit =

A

PRF / 2

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2
Q

Max detectible Doppler shift aka =

A

Nyquist limit

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3
Q

Vmax =

A

(PRF * v) / ( f transducer * cos theta)

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4
Q

Frame rate (temporal res) =

A

v / (N scan lines * depth)

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5
Q

Prosthetic MV - abnormal values

A

MG >10
VTI ratio (prosth/lvot) > 2.2
EOA = SV/VTI prosth
EOA <1 bad (EOAi <0.9) bad
low EOA + PHT <130 –> severe PPM!
VTI >2.2, PHT >130 –> obstruction
VIT > 2.2, PHT <130 –> pathologic regurg

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6
Q

EOA MV prosth =

A

SV / VTI prosthesis

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7
Q

PASP
PAEDP
mPAP

A

4(TR)2 + RAP
4(PR end diast)2 + RAP

90-(.6AT) or 80-(.5AT)
.61(RVSP) +2 ***remember RVSP includes RAP! don’t forget to get the full RVSP into the equation
4(PR peak vel)2 + RAP

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8
Q

PVR =

A

(TR peak vel / RVOT VTI) *10 + .16

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9
Q

Axial resolution =

A

SPL / 2
(and temporal res/frame rate = PRF/2)

Note: you want axial res # to be LOW for better axial res

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10
Q

Duty factor =

A

PD / PRP

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11
Q

Matching layer thickness =

A

1/4 λ

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12
Q

PZT (pioezelectric crystal thickness) =

A

1/2 λ

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13
Q

Near-field depth =

A

d^2 / 4λ

(d = diameter of probe)

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14
Q

Which tissue boundary has highest reflection?

A

Air / soft tissue boundary

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15
Q

As PD increases, SPL does what

A

Also increases

PD goes up, SPL goes up…and if SPL goes up, axial res worsens (higher #)

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16
Q

2nd order =

A

twice the frequency

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17
Q

Normal Tei index (MPI)

A

LV <0.39
RV <0.28

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18
Q

Normal propagation velocity
Abnormal =

A

50 cm/s

ABnormal is <50 cm/s

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19
Q

Athlete’s heart falls into which box?

A

Eccentric

  • increased LV mass, dilated LV cavity (but <6 mm)
  • increased LA vol, symmetric LVH
    **NORMAL GLS and LVEF
    **increased e’ velocities (lateral and septal)
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20
Q

Signs of LVAD thrombosis (4)

A

4 Consequences of poor LV unloading d/t thrombus:
-increased AV opening (w/ every beat)
-increased LVIDd
-increased MR
-septal shift to RV

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21
Q

Signs of LVAD suction

A

Low flow alarm
LVIDd small
Septum shift to left (into LV)
—rx: decrease speed

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22
Q

PV flow:
High LVEDP:
Afib:
Severe MR:
ASD:
Severe MS:

A

High LVEDP: prominent AR reversal
Afib: loss of AR reversal
Severe MR: holosystolic flow reversal
ASD: fusion of A & D
Severe MS: S»D (D falls)

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23
Q

Exclusion criteria (can’t have TEER for MR…RRRRRs):

A

1) flail gap >10 mm
2) flail width >15mm
3) depth > 11mm
4) length less than 2mm

Need small gap, width, and depth. But need large length.

Also MVA must be >4, MG<??
Ideally A2/P2 pathology

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24
Q

Barlow valve aka:

A

MVP
mid-systolic click

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25
What happens to Y descent in: -tamponade -CP
Tamponde - absent Y descent CP - exaggerated Y
26
Which is best to eval pericardial thickness?
TEE
27
Angiosarcomas
-3:1 male predominance -a/w pericardial effusion -can completely fill the RA (80% are in the RA) -rapidly fatal, often present late
27
Distinguish CP from COPD
Both can have >25% mitral inflow variation w/ respiration. But, COPD does not have restrictive filling of the mitral inflow, unlike CP. Also, COPD has *marked* increased SVC flow with inspiration.
28
Septal bounce d/t chronic CP - M-mode
Early diastolic motion of septum & LV posterior wall (looks like beaking but into the RV), d/t rapid and then suddenly halted diastolic filling
29
SVC flow w/ inspiration
In COPD: increases MARKEDLY w/ insp In nml pts: increases w/ inspiration In CP: increases only minimally w/ inspi
30
CP: what happens to strain?
Normal longitudinal Reduced circumferential & rotation strain
31
Down syndrome with AVSD often have ToF
32
AVSD a/w cleft in which leaflet?
Anterior MV leaflet
33
AVSD a/w ____ rotation of the pap muscles (what direction), and ____ movement of the LVOT?
Lateral rotation of papillary m. Anterior "sprung forward" LVOT --> LV inlet: LV outlet ratio <1
34
CoA of ___ % will begin to affect blood pressure? MC type of VSD a/w CoA?
50% Peri-membraneous VSD
34
Supracristal (subpulmonary) VSD is a/w which other valve dz?
AR bc the AV cusp prolapses into the VSD
35
Alagille is a/w ?
Pulmonary branch stenosis or RVOT obstruction
36
Holt-Oram is a/w?
Secundum ASD
37
Turner (45XO) is a/w?
CoA & BAV
38
DiGeorge (22q11) is a/w?
Truncus arteriosus Interrupted ao arch Hypoparathyroid (no thymus)
39
Types of interrupted ao arch
Type A (after L subclavian) Type B (btwn L common carotid & L subclavian) Type C (btwn R innom. & L common carotid)
40
Abd Ao Doppler in: -severe AR -CoA
Severe AR: holoDIAstolic flow reversal CoA: delayed upstroke w/ diastolic runoff
41
Grading pulmonic stenosis by velocity Severe stenosis gradient?
mild <3 m/s mod 3-4 m/s severe 4 m/s thus, severe is peak gradient 64 mmHg
42
Noonan is a/w (name 3):
PS HCM ASD
43
Gorlin syndrome a/w:
cardiac fibroma (in the septum or free wall) nevoid basal cell ca.
44
Carney syndrome a/w:
-multiple myxomas -endocrine tumors (adrenal, thyroid, testicular) -acromegaly -schwannomas -blue nevi & skin lentigines (brown)
44
Myxoma sx:
Dyspnea Fever d/t IL-6 Weight loss - myxomas have a stalk to the atrial septum
44
Tuberous sclerosis a/w:
rhabdomyoma (kids) --> rhabdomyomas are actually hamartomas --> 80% of pts w/ rhabdomyomas have tuberous sclerosis -->50%+ rhabdos regress seizures TSC gene mutation
44
PFEs are:
-usually single -have a pedicle attached to valve -rarely cause regurg or other valve dysfcn -but DO often p/w embolic phenom/TIA! --> offer surgery if sx develop, or tumor becomes mobile. Surgery is curative (do not recur)
45
MC malignant tumor of heart
1) mets from elsewhere 2) angiosarcoma (MC *primary* malignant tumor of heart)
46
Synovial sarcoma is d/t:
translocation of 18 & X chromosomes it's malignant, rare, poor prognosis
47
Prosthetic TV stenosis:
-PHT >230 (mechanical) -MG >6 mmHg (in the absence of high output state like anemia, hyperthryoid, sepsis) -peak vel 1.7 m/s
48
RV restrictive filling
Tricuspid E/A >2.1 decel time <120 (similar to MV restrictive)
49
JVP 15 cm of water = ? RAP
15cm H2O * 0.7 = 10 mmHg RAP
50
mPAP = PADP + 1/3 pulse pressure =
PADP + 0.33(PASP - PADP) ***remember to add RAP to get the PADP and PASP (which is RVSP unless there's PV disease)
51
VSD calculation
SBP - VSD 4v2 = RVSP (and PASP if no stenosis) 150 BP - 4(5.5^2) = 29 mmHg = RVSP
52
Severe TR: RVSP will be very similar to the RA "v" wave pressure
53
Hepatic vein AR wave: with RVH, RV stiffness --> prominent *AR* signal in hepatic veins with RA contraction.
with RVH, RV stiffness --> prominent AR signal in hepatic veins with RA contraction.
54
Narrower diameter --> ____ divergence Lower frequency --> ____ divergence
Narrow (smaller) diameter crystal will INCREASE divergence Lower frequency will INCREASE divergence divergence = 1/ diam crystal*f
55
Divergence =
1/ (diam * f) More divergence = wider beam in far field, but worse lateral resolution in far field
56
How to reduce aliasing?
-increase the angle (which makes cosine theta smaller) -increase the PRF (which means, lower depth, lower PRP, less listening time) -use a lower frequency transducer -use baseline shift
57
Increasing the Nyquist limit makes the system less sensitive to what?
Makes system less sens to low velocities (and regurg jets will appear smaller)
58
λ (mm) =
λ (mm) = 1.54 / __ MHz
59
The major source of u/s information used to create a 2D image is:
backscatter
60
Lateral resolution is determined by:
beam (pulse) width/diameter (and therefore, depth)
61
Point spread artifact is another way of describing *suboptimal* lateral resolution
62
Beam diameter/width changes with depth, so lateral resolution also changes by depth
63
Sound travels very rapidly in bone because:
Bone is high stiffness, low density
64
PRF is determined solely by:
Depth So if 2D imaging and M-mode are at same depth of view, the PRF is equal in 2D and M-mode
65
Refraction only occurs if there is:
Oblique incident & different propagation speeds between 2 mediums
66
Narrower sector is another way of saying decreased scan lines
67
Tissue harmonics:
All harmonics are the result of non-linear behavior -contrast harmonics (low MI!) are created from non-linear behavior of the microbubbles -tissue harmonics are created from non-linear behavior of sound waves as they propagate
68
PRP =
13µs * cm depth If a pulse emitted has a go-return time of 125 microseconds, what is the estimate for the distance that the pulse traveled? 125µs / 13µs = 9.6 cm---> then multiply by 2 to account for going AND coming back
69
Water attenuates sound the LEAST
sound attenuates more in air, bone, lung, soft tissue
70
PW Doppler suffers from:
aliasing
71
CW Doppler suffers from:
range ambiguity
72
Lateral resolution depends on: Axial resolution depends on:
Lateral resolution depends on: pulse WIDTH (aka beam diameter) Axial resolution depends on: pulse length (SPL) --> axial res = SPL/2
73
Water has the least attenuation Air has the least impedence
74
What to do if you can only see reflectors in the far-field, but not near?
Adjust the system's compensation
75
What to do if you can only see reflectors in the near-field, but not far?
Adjust the system's compensation
76
What to do if the image is saturated (too bright everywhere)?
Decrease the output power
77
CW vs PW
CW: minimum of 2 crystals, has range ambig, unlimited max velocity, **uses UNdamped, hi Quality factor, LOW bandwidth transducer (has more sensitivity to small doppler shifts)
78
Color variance map (vs velocity):
adds green/yellow to show turbuence
79
Post-TAVR paravalular leak: moderate = ?%
10-30% of clockface
80
Complication with plugging a prosthetic MV paravalvular leak?
MV leaflet impingement
81
TAVR issues with low vs high implantation Underexpanded:
Low implantation: -paravalvular regurg -MV disruption -heart block Underexpanded: -paravalvular regurg -prosth regurg -decrease valve durability
82
Rvol =
EROA * VTI (you haven't used VTI yet for EROA, only PISA and velocities- aliasing and regurg vel)
83
Tenting area >6 cm2 =
Severe MR
84
AI will increase the LVOT VTI MR will increase the MV VTI
85
SPL =
# cycles * wavelength
86
Mechanical index =
Peak neg pressure / sq root frequency
87
Doppler shift =
PRF/2
88
CW

M2016 (2 decks)

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