test 2 Flashcards
Pressure waves are sent through body and echo waves return to the transducer elements and are processed to create ultrasound images
ultrasound
the major source of sound wave attenuation is soft tissue (the conversion of energy to heat)
absorption
occurs when sound waves encounter a boundary between two different media.
reflection
when waves are reflected off of bone an ____ _____ will be created
acoustic shadow
when us waves encounter a medium with non-homogenous surface
scatter
the consequence of scatter is
speckle
why is gel used in ultrasound
ensures proper contact between transducer and patient, for sound to travel through tissues
frequency (Hz) of the wave is measured in
cycles per second
Ultrasound imaging frequency
1-20 MHz
what frequency is better for deeper structures
lower frequency waves
frequency that provides better resolution for shallow structures
high frequency waves
Ultrasound gets _____ in tissue, signals get ____ in deeper structures, resulting in _____images.
Ultrasound gets attenuated in tissue, signals get weaker in deeper structures, resulting in darker images
_______ may prevent imaging behind solid structures
absorptions
_________may prevent imaging behind solid structures or air
Hard reflections
ultrasound transducer that provides a wide, near field image
Curved Array
when scanning for fetus or abd what type of transducer would you use
Curved array
pie shaped image, quality not as good as curved array.
phased array
what type of transducer would be better for ultrasounding the heart behind ribs
Phased array
transducer that gives the best resolution, used in vascular and superficial soft tissue studies
linear array
runs parallel to the ground separating superior from inferior
transverse plane
oriented perpendicular to ground separating pt left from right
Sagittal/longitudinal plane
separates the pt anterior from posterior
coronal plane
used to image structures that don’t line up with the other planes
Oblique plane
commonly used mode in ultrasound, different shades of gray in a 2 dimensional picture
B mode
captures returning echos along one line of the real time image. Used to quantify motion over time
M mode (motion mode)
frequency shift caused by sound waves interacting with a moving target
Doppler
used to visualize and quantify blood flow information
pulsed wave doppler
shows approx speed and direction of blood flow inside the vessel
color doppler
is used to identify blood flowing toward the transducer
red
is used to identify blood flowing away from the transducer
blue
looks at the strength or amplitude of the returning signal. assigns a color based on the strength or amplitude of the returning signal
power doppler
P on the R side of the cone image indicates what mode
cardiac
P on the L side of the cone image indicates what mode
standard
in cardiac mode the probe should be facing the
L shoulder
the Left ventricle should be on what side of the screen for cardiac mode
Left
in standard mode the probe should be facing the
Left hip
what is the optimal pt positioning for a cardiac ultrasound (Transthoracic echocardiography)
L lat decubitus positon which brings heart forward
steps for Parasternal Long Axis for Echocardiography
1) cardiac mode
2) Indicator to R shoulder
3) nipple line/4th intercostal space
3 Ls for success
for the PLA put the LV on the Left of the screen
gold standard for estimating ejection fraction in Echocardiography
Eyeballing EF by looking at the squeeze of the heart, and how closely the anterior mitral valve leaflet gets to the intraventricular septum
in the PLA view
what are the exceptions that would falsely quantify EF using the eyeball method
Aortic regurgitation
mitral stenosis
fluid is anterior to the descending aorta in the echocardiogram
Pericardial effusion
if the effusion is posterior to the descending aorta
Pleural effusion
diastolic collapse of the Rv with clinical symptoms of hypoperfusion (hypotension, tachycardia, syncope, sob, ect)
Pericardial tamponade
if you start at the PLA and rotate the probe 90 degrees clockwise towards to pt L shoulder, fan towards apex then up towards base
Parasternal short axis (PSA view)
“fish mouth and mercedes benz sign view”
to get the mid papillary on the PSA
fan towards apex
papillary muscles in view
Mitral valve view on PSA
fan probe towards base
“fish mouth mitral view)
Aortic valve view on PSA
Fan probe towards base
Mercedes-benz aortic valve
D sign on PSA
R ventricular strain
Apical 4 chamber
Left axilla,
Fan upwards at apex (towards pt head)
Subxiphoid View on Echocardiography
Subxiphoid region
Indicator to Left
overhand grip on probe
probe almost parallel to skin
IVC measurements help with
fluid management
caval index =
preload reserve
electrical path for heart
SA node ->AV node ->HIs purkinje system -> R and L bundle
electricity that moves towards a lead creates ___________ known as a ____
electricity that moves towards a lead creates a positive deflection known as a R wave.
electricity that moves away from a lead creates a _______ or an _____
electricity that moves away from a lead creates a negative deflection or an S wave
The leads that are placed across the chest are known as the ______-
Precordial leads (V1-V6, V3R, V4R)
Leads I, aVL, V5, V6, V7 cover the
L lateral side of the heart
Leads aVR, V3R and V4R cover the
R side of the heart
Leads II, III and aVF are classically known as the
inferior leads
V1-V4
anterior leads
V1 and V2
give a better idea of how the septum depolarizes
each small box on the EKG is
40 milliseconds in duration
in terms of the amplitude, the ECG is performed at
10millimeters per millivolt, 10 squares high
mathematical way of calculating heart rate on an EKG strip
Count squares between each QRS complex (each small square is 40milliseconds)
# s x 40ms = cycle length divide 60,000 by the cycle length and this will give you the heart rate in beats per minute
Estimation method for calculating HR
find QRS closest to a thick black line and start counting at the next thick black line…300, 150, 100, 75 till you get to the next QRS
or 300 divided by 4 will give you the same
NSR is set by the
SA node
Atrial contraction produces what on the EKG
P wave
Ventricular contraction produces what on the EKG
QRS complex
In normal adults, electricity moves downwards and to the left towards the left ventricle.
what does this do to the ekg
On the EKG you will see a R wave in lead I and in aVF
In children, the _____ is more dominant. As a result, electricity tends to move downwards and towards the R side of the chest. This is seen in what age?
R ventricle
over the first 6 months it starts to shift
If a pt had a right axis deviation, you would see a
lead 1 would have Prominent S wave
In II, III and aV5 they all have prominent S waves so they have the negative deflections
Superior Axis
what does a Superior axis indicate and who is it seen in commonly
Atrioventricular canal
- common in pt with Trisomy 21
Tricuspid Atresia
what represents atrial depolarization (contraction)
P wave
1st half of the P wave represents the
R atrial contraction
2nd half of the P wave represents the
L atrial contraction
Normal values for P wave
No more than 3 squares high and 3 squares wide
Less than 0.3 millivolts or duration less than 120 milliseconds
where is the best place to look at the P wave
leads II and V1 (most prominent deflections on an ECG)
Large peaked P wave is seen in
R atrial enlargement (usually >0.3 millivolts)
a Large notched P wave is seen in
L atrial enlargement
usually greater than 120 milliseconds
what does L atrial enlargement look like in lead V1
slurred terminal portion of the P waves (Biphasic P wave)
what part of the EKG reflects intra-atrial conduction
PR interval
A normal PR interval is less than
200milliseconds
1st degree heart block refers to a PR interval
greater than 200miliseconds
electricity from time to time gets blocked in the AV node so every now an then you have a P wave without a QRS complex
2nd degree heart block
second degree heart block that the PR intervals get longer and longer until a QRS is dropped then it starts over
Mobitz type 1 (Wenckebach)
P waves that do not have a QRS complex afterwards. Before the dropped QRS, the PR interval stays the same throughout
Mobitz type 2
which 2nd degree heart block is always pathological
Mobitz type 2
There is no impulses conducted through the AV node to the ventricles
3rd degree heart block
on the EKG strip the atrium and ventricle are beating independent of each other
3rd degree heart block
abnormal conduction through the ventricles can be seen by evaluating the
QRS complex
wide QRS complex is >
120 milliseconds
what has a wide QRS
R bundle branch block because electricity moves slower through the R Purkinje fibers and thus the left ventricle activates first
In R bundle branch block what does EKG show
first half of QRS complex = LV depolarization
V1 will have a small R wave
V6 will have a qR complex
(left ventricle depolarizing)
in V1 you see a tall slurred R prime (“bunny ear complex”)
V6 you see a slurred S wave as electricity moves away from V6 as the R ventricle contracts
L bundle branch block
V1 has an rS pattern
V6 has the bunny ear pattern with a tall notched R wave
In terms of hypertrophy the QRS deflections reflect the
mass of ventricles
what does R ventricular hypertrophy show on EKG
large R wave in V1
large S wave in V6
abnormal T waves in the R precordium
QR pattern in V1 or an RSR prime pattern (R prime has to be quite large) in V1 can also be used to diagnose RVH
L ventricular hypertrophy
large R wave in V6 large S wave in V1 or RS ratio greater than 98% percentile T wave inversions in the Left lateral precordium can also be looked for as can a left axis deviation
the end of the QRS complex to the beginning of the T wave is the
ST segment - isoelectric
changes in the ST segment can reflect
ischema or inflammation
diffuse ST elevations across all of your leads
Pericarditis
what shows ventricular depolarization and can change as the patient ages
T wave
In general the T wave follows the axis of the
QRS
T wave changes along the R precordium is observed in leads
v1-v3
from birth to seven days what do you see on the EKG
positive T waves noted
from 1 week to adolescence what happens to the T waves
the t waves flip over and are negative
After your teenage years, what happens to T waves
they flip over and become positive in the r precordium
after one week old, positive T waves seen in V1 reflect
RVH
the beginning of the QRS complex to the End of the T wave
QT interval
when measuring QT interval what leads do you use
Lead II and V5
Pt with prolonged QT interval is at risk for
ventricular arrhythmia and sudden death
Bazett’s formula
Divide QT interval by the sq root of the preceding RR complex (ms between QRS complexes right before the QT interval of interest)
In general the number to keep in your head for Bazett’s formula is less than
QTc = 450 ms
Anatomic presence of an accessory conduction pathway that allows for reentrant SVT
Wolff-Parkinson White (WPW)
what population is at higher risk for WPW
males
Symptoms of WPW
palpitations presyncope/syncope sudden cardiac death Dizziness Chest Pain
characteristic ECG findings associated with WPW
short PR interval
delta wave which is a slurring of the P wave into the QRS
widening of the QRS complex
Associated congenital heart disease lesions in WPW
Ebstein anomaly (abnormal development of tricuspid valve)
Hypertrophic cardiomyopathy
L-transposition of great arteries (congenitally corrected transposition of great arteries, ventricular inversion)
diagnostics of WPW
ECG
Echocardiogram
Holter exercise stress ECG
Treatment WPW
B Blockade for symptomatic patients- only if not able to have ablation
Activity restriction with pts who have high risk pathways
Intracardiac catheterization for electrophysiology studies (EPS) with ablation of accessory pathway
meds contraindicated in WPW
Ketamine
Caution in reversal agents - neostigmine/atropine/glycopyrrolate - tachyarrhythmias
If pt has irregular wide complex tachycardia, these meds are highly contraindicated- at higher risk for life threatening ventricular arrhythmias
Adenosine
CCBs
B Blockers
genetics Long QT
Can be inherited in both autosomal dominant and receptive fashions
Symptoms Long QT
syncope/presyncope
Palpitations
Sudden cardiac arrest
Lightheadedness
Normal QTc
males: <440ms, females <460ms
For assessing QTC what leads do you use on EKG
II or V5
How do you calculate QTC
Step 1: Calculate the QT interval (every small box is 400ms, big box is 200ms)
Draw a tangential line along the descending slope of the T wave. Where it intersects at the baseline would be the end of the QT interval. The beginning of the QRS to the end of the T milliseconds
Step 2: Calculate the R-R interval preceding the QT interval you calculated.
STep 3: Using Bazett’s formula: The QTC is equal to the QT interval divided by the square root of the preceding R to R interval.
2 other arrhythmias seen in long QT
Torsades de point is seen in Long QT syndrome - polymorphic ventricular tachycardia that varies from a large amplitude QRS complexes to small amplitude QRS complexes and goes back and forth.
PALS algorithm
Treat with magnesium sulfate to reverse
Pseudo 2:1 AV block in the presence of a long QT
In neonates - poor prognosis with high risk of mortality. High suspicion for needing an ICD.
How do you treat Torsades de point in long QT
magnesium sulfate
PALS algorithm
diagnostic tools for long QT
ECG
Stress Testing
Holter monitor
Genetic testing
Probability tool used in long QT
Schwartz Score (probability scoring)
Less than or equal to 1 point - low (genetic testing should not be pursued)
1.5-3 points - Intermediate (genetic testing for pt and recommended ECG for relatives)
Greater than or equal to 3.5 points - High (genetic testing probability of positive is 80%)
what are the 3 types of long QT and what are their frequencies
LQTS1 -most common
LQTS2
LQTS3- least common type
Associated gene mutation for
LQTS1
Mutation in KCNQ1
Associated gene mutation for
LQTS2
Mutation in KCNH2
Associated gene mutation for
LQTS2
Mutation in SCN5A
LQTS1 due to loss of function in ?
Due to loss of function in the potassium ion gene
what is the key EKG feature for LQTS1
Early peaking T wave that comes soon after QRS complex