Cardio GW Flashcards by Hannah Minton

Atrial depolarization

P wave

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AV slowing pulse down

PR interval

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Ventricular depolarization

QRS wave

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Rest period between depolarization and repolarization of vent

ST segment

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Repolarization of ventricles

T wave

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Depression of ST segment means

decreased blood flow to myocardium

Indicated myocardial ischemia

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Elevated ST segment may mean

Acute MI

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What is hibernating myocardium

severely, chronically ischemic tissue that is viable but appears to be nonfunctioning and has decreased perfusion

-high likelihood of benefiting from revascularization

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What is myocardial stunning

A temporary response where the myocardium is deprived of blood flow.

Occurs after the pt experiences acute episode of severe ischemia or an acute MI that is terminated by thrombolysis or revascularization

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Myocardial perfusion imaging RPs

Tl201 thallous chloride

99mTc Sestamibi

99mTc Tetrofosmin

Rb82 chloride, N13 ammonia, F18 FDG

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Exercise prep

Fast for at least 3 hours prior

No physical exertion 12 hours prior

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Drugs that can affect exercise

Beta blockers 72 hrs
Calcium channel blockers 48-72 hours
Antihypertensives 4-7 days
Anti arrhythmic agents 2 days
Sedatives 1 day
Nitroglycerin 1 hr
Long acting nitrates 12 hr
Digitalis (digoxin) 1-2 weeks

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Target heart rate calculation

(220 - pts age) x 85%

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Right and left arm electrode placement

Midclavicular line, below clavicle

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Rt and left leg electrodes are placed where

Just below rib cage on either side

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Pharmacological stress test prep

NPO minimum 4 hours prior
D/C xanthine derivatives 12-24 hours
No caffeine 12 hours prior

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If possible, aminophylline should not be administered until ____ minutes after tracer

1-2 minutes

Can cause false positive if injected too early

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1-6 EKG placement

1 - fourth intercostal space on left side of sternum
2 - fourth intercostal space on right side of sternum
3 - in between 2 and 4
4 - fifth intercostal space directly below midclavicular line
5 - right beside or 4 at left anterior axillary line
6 - right beside or 4 at left midaxillary line

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Dipyridamole (Persantine) contraindications

Bronchospasm, pulmonary disease, active wheezing, hypotension, severe mitral valve disease

MI within 2 days, unstable angina within 48 hours, severe aortic stenosis, severe obstructive hypertrophic cardiomyopathy, and severe orthostatic hypotension

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Contraindications for adenosine

Same as dipyridamole +

Second or third degree AV block (without pacemaker)

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If patient is taking oral dipyridamole for heart medication and needs stress test

Cannot give adenosine

Must d/c dipyridamole 2 days before regadenoson

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Contraindications for regadenoson

2nd or 3rd AV block (without pacemaker)

Bronchospasm, low BP, hypersensitivity to reg.

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Contraindications for exercise

LBBB

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Combination of low level or isometric exercise with dipyridamole, adenosine, or regadenoson (during or after drug) has what benefits

Decreased side effects
Decreased sub diaphragmatic uptake
Increased target to background ratio

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Dobutamine stimulates what receptors

Dobutamine is indicated for

Pts who cannot exercise and cannot undergo pharmacologic stress due to severe bronchospastic disease

Pt prep for dobutamine

NPO at least 4 hours Withhold beta blockers for 24-48 hours

Contraindications for dobutamine

Recent MI less than 1 week, unstable angina, critical aortic stenosis, atrial tachyarrhythmias, v-tach, uncontrolled HBP, aortic dissection, large aortic aneurysm

Planar MPI, a zoom factor of _____ should be used if using large FVOC

Zoom factor of 1.2-1.5

Diaphragmatic attenuation on planar MPI may cause

False positive defect in inferior wall of left ventricle

Quantitative myocardial perfusion information on planar imaging

Circumferential profile analysis

Heart to lung ratio things to remember

Same size ROIs The myocardial ROI should not be placed on the anterior or anteriolateral wall because of heart/lung overlap

SPECT MPI acquisition step and shoot method

32 or 64 stops for 180° Or 64 or 128 stops for 360°

recommended pixel size for SPECT MPI

6.4 + or - 0.2 mm For a 64 x 64 matrix

ECG configuration for gated MPI

Standard lead II configuration

Gated SPECT allows for evaluation of

Wall motion, Thickening, And EF

SPECT MPI most common low pass filter

Butterworth -smooths and suppresses noise, loss of resolution

Reconstruction of planar projections may be performed with

Filtered back projection technique or iterative technique

Reconstruction methods for planar MPI

Filtered back projection Iterative reconstruction

Filtered back projection uses what filter

Ramp (high pass filter)

SPECT reconstruction MPI uses what filter

Butterworth (low pass filter)

which reconstruction method for planar MPI is more accurate

Iterative reconstruction

Tl201 thallous chloride is a ____ analog

Potassium -this is why tl201 is redistributed because of the sodium potassium pump -potassium is used to make heart contract

Tl201 redistribution can be seen

On delay images (2-4 hours) Resting images 24 hour delays Or reinjection images

SPECT or planar is more commonly preferred for Tl201 stress/redistribution images

SPECT, unless pt cannot lie still

Tl201 planar injection to image time

10 minutes

Tl201 dose

2-4 mCi

Info about tl201 energy

Mercury X-rays in the 68-89 keV range are emitted during the decay - a 30% window is over 72 keV An optional second 20% window is over 167 keV

Tl201 planar imaging acquisition parameters

LEAP 128 x 128 word mode 600,000 counts minimum

Tl201 instructions between stress image and 3-4 delay image

Don’t eat May have a light snack but avoid caffeine, sugar, and carbs because glucose ingestion results in accelerated clearance of tl201

How long is each image acquired for in Tl201 SPECT

40 seconds

Resting Tl201 indication

Previous possible Acute MI

Resting tl201 dose and acquisition

2.5-3 mCi Image at 10-15 mins Image delays at 3-4 hours

Stress tl201 dose and acquisition

2-4 mCi Image at 10 minutes Image delays at 3-4 hours

Reinjection tl201 dose and acquisition

Wait until after delays are taken, then inject 1.5 mCi at 3-4 hours or even 24 hours Image at 10-15 minutes

What is the purpose of reinjection images for Tl201

Increase the sensitivity of stress/redistribution imaging for the detection of viable myocardium

How is sestamibi excreted

Hepatobiliary

Injection to image time for Sestamibi

Rest: 15-60 minutes Stress: 60-90 minutes *max 4 hours

Acquisition time per view for Sestamibi

Planar: 5 mins/view Gated planar: 10 mins/view SPECT: 20-25 secs/stop for high dose 40 sec/stop for low dose

differences between Tetrofosmin and Sestamibi

Can image earlier due to rapid uptake and background clearance Localizes in mitochondria Clears from the liver and lungs faster

Dual tracer MPI SPECT

Rest: Tl201 2.5 mCi Stress: 99mTc agent 22-25 mCi

MUGA/ERNA RP and dose

99mTc pertechnetate labeled RBCs (15-30 mCi) Or 99m Tc human serum albumin

Tagging method % labeling efficiency

In vitro: 95% Modified in vivo: 90% In vivo: 60-90%

Resting muga pt prep

None

Number of counts for each view for MUGA

3-7 million

During MUGA, if assessment of right ventricular function is indicated, can do a gated first pass study but remember:

Do it in list mode Acquired in 10°-15° RAO position Take flow while injected labeled RBCs

MUGA data is acquired by dividing the cardiac cycle into _____ frames

16, 24, and 32

The time that an individual frame will accumulate counts during a single cardiac cycle depends on

The average length of the r-r interval

Ventricular EF formula

LVEF% = [(EDV - EDS)/ EDV] x 100

The volume of blood ejected by either ventricle during ventricular systole

Stroke volume

The volume of blood that the heart pumps per minute

Cardiac output

Cardiac output formula

CO = SV x heart rate

The capacity of the ventricle after it is completely filled with blood; the largest volume reached by ventricle during a cardiac cycle

End diastolic volume

The residual capacity of the ventricle at the end of contraction; the smallest volume reached during a cardiac cycle

End systolic volume

Stroke volume formula

SV = EDV - ESV

First pass is useful for

Right ventricular dysfunction Interventricular shunts Ischemia and infarction

First pass RP

Any 99mTc pharmaceutical If only first pass study then DYPA or Pertechnetate is preferred

What must be done before first pass study

Baseline ECG

What is essential for a successful first pass study

Regular rhythm Small rapid unfragmented bolus of <1mL with large needle, flushed with 10 mL saline Because first pass are representative of only 2-3 beats

Acquisition preference for first pass

Multi crystal camera or gamma camera that can take 200,000 counts/sec or greater High sensitivity collimator

Cardio GW Flashcards

(80 cards)