Ch 6

Stress Echo

What is a stress echo?

a stress test and an echo performed pre/during/post echo

what is an echo most commonly used to detect?

coronary artery disease/ischemic heart disease in patients with angina or other symptoms

what are the two types of stress echos?

physiological (exercise) and pharmacological

what are the two kinds of physiological stress echos?

treadmill and supine bike

what drug is used during the pharmacological stress echo?

dobutamine (most common) but sometimes a vasodilator (dipyridamole, adenosine, regadenason)

Is physiological or pharmaceutical stress echo preferred?

physiological

What are the hemodynamic effects of stress on the heart?

• ischemia

• myocardial supply and demand issue

• WMA

• valvular abnormality

What are the advantages of a stress echo?

• non invasive (IV is required for pharmaceutical SE or UEA

• no exposure to radioactive material, dye, or radiation

• relatively inexpensive

• quick and reliable technique with immediate rfeedback

• more sensitive and specific than a standard 12 lead EKG stress test

• ability to evaluate cardiac anatomy and fxn prior to stress so we can rule out contraindications

• perfect for the patient with abnormal EKG becuase it shows electrical response and mechanical response to stress

• provides a live, visual connection between the patients symptoms and cardiac fxn

What are the indications for a stress echo?

• abnormal EKG

• athletes heart

• CAD/IHD

• chest pain of unknown origin

• chest radiation

• exercise related arrhythmia

• exercise dyspnea

• systolic or diastolic HF

• heart transplant

• left bundle branch block

• nonischemic cardiomyopathy

• evaluate cardiac fxn prior to the start of an exercise program

• predicts prognosis

• previous nondiagnostic 12 lead stress test

• pre-op clearance/risk stratification

• pulmonary hypertension

• RV fxn/TAPSE

• presence of risk factors

• valvular disease

• other

What does the ASE require to be done prior to a stress echo?

if a TTE has not been preformed recently, a baseline, resting TTE is necessary prior to stress

What must happen if there are contraindications found prior to stress echo?

they must be notes and SE is postponed or cancelled

What is an absolute contraindication?

a contraindication that requires a stress echo to not be performed under any circumstances

What is a relative contraindication?

a contraindication that may be overlooked if the physical determines that the benefit of performing the stress echo outweighs the risk; SE is performed with extreme caution

What are the contraindications for a stress echo?

• significant decrease in EF

• elevated cardiac enzymes

• known, severe CAD

• large aortic aneurysm, unless indicated for pre-op clearance

• LVOTO, AS cardiomyopathy

• mobile thrombus

• MI within the last 48 hours

• myocarditis

• patient is combative/uncooperative/refuses SE

• pericarditis

• pregnant

• pulmonary embolus

• seizures

• significant EKG findings - ventricular arrhythmia, 2nd or 3rd degree heart block

• suboptimal echo images/TDS - consider UEA

• suspect recent MI that has not been fully evaluated

• syncope

• uncontrolled HTN

• unstable angina

What is the goal of a stress echo?

achieve the target HR for at least 1 min

What is the target HR?

85-90% of the patients predicted max HR

What is the patients predicted max HR?

220 - patients age in years

What is the normal cardiac response to stress?

increased LV wall contractility, decrease LV volume and size (greater demand = stronger contractions = increased HR)

What is CAD?

plaque build up within the lumen of a coronary artery and blocks blood flow - can occur in any location within any or all of the coronary arteries

What does CAD result in?

WMA

Are WMA always obvious at rest?

no

When do most WMA appear?

during or immediate post stress

What can it mean if a WMA appears at low stress?

that the coronary obstruction may be more severe with less myocardial perfusion reserve

What can it mean if a WMA persists into recovery?

may be due to stunning an indicates more severe disease

what does it mean if the WMA presents towards the base of the heart?

blockage is located in the proximal portion of the coronary artery

what does it mean if the WMA presents towards the apex of the heart?

blockage is located in the distal portion of the coronary artery

What does a negative SE mean?

it was a normal stress echo - normal global and regional wall motion at rest and at stress

What does a positive SE mean?

there is a fixed WMA or new/worsening WMA indicative of ischemia

What is a fixed WMA?

a WMA present at rest and during stress

A resting WMA unchanged with stress is classified as what and usually represents what?

fixed; prior MI

What is a provoked regional WMA?

normal WM at rest becomes hypo/a/dyskinetic/aneurysmal during and/or post stress OR hypo kinetic WM at rest becomes more hypo kinetic or worse at peak and/or immediate post

What other criteria usually indicate WMA during stress?

• decrease in overall EF from rest to peak and/or immediate post - evaluate wall motion and thickening from diastole to systole

• an increase in LV volume and size from rest to peak and/or immediate post

Ischemia may delay the onset of contraction known as __ and may __ __ of contraction

tardokinesis; decrease velocity

A false positive SE may be due to what?

microvalvular disease, endothelial dysfxn, vasospasm, small vessel CAD, amyloidosis deposits, or apical ballooning syndrome

What score does a normally functioning wall segment receive?

1

How do you calculate the wall motion score index?

sum of all segments analyzed / total number off segments analyzed

The 16 segment model is typically used when?

regional wall motion and thickening are scored

The 17 segment model is typically used when?

if myocardial perfusion is assess such as single photon emission computed tomography (SPECT) or if SE is compared to another modality such as SPECT or PET scan

When is UEA indicated according to the ASE?

when 2+ continuous wall segments and/or coronary artery territories are not well visualized

What score does a hypokinetic (systolic increase in thickening >40%) wall segment receive?

2

What score does a severe hypokinetic or akinetic (systolic increase in thickening <10%) wall segment receive?

3

What score does a dyskinetic (paradoxical motion away from center of LV) wall segment receive?

4

What score does an aneurysmal (diastolic deformation) wall segment receive?

5

What does tissue harmonic imaging do?

reduces near field artifact, enhances myocardial signals, and improves endocardial boarder delineation

What part of the cardiac cycle does the machine capture the images off of for a stress echo?

R wave

What are the stages of the SE?

rest, peak, impost, final

What are the most common SE views?

LAX, SAX, 4C, 2C - consider substitution 3C if better quality than LAX

Within each quadrant of the quad screen view, what part of the cardiac cycle is being shown and in how many frames?

systolic or full beat; 8-12 frames

How does the quad screen view being broken down into the same number of frames per image help assessment of the walls?

allows for caparison of images taken at different heart rates

What should frame 1 include?

end diastole - LV is fully expanded and AOV is closed

What should frame 2 include?

early systole - AOV opens

What should frame 3-7 include?

continuation of systole - LV contracts, wall thickens and AOV remains open

What should frame 8 include?

early diastole - AOV closes and LV pops back out providing verification that end systole was included on 7

What is the standard Bruce protocol?

• every 3 min increase grade and velocity

• if a low level se is indicated, utilize a modified bruce or naughton protocol

Terminate the SE if:

• THR was achieved for at least one minute

• significant symptoms or can’t go on

• EKG changes - ST segment changes or arrhythmia

• HTN (systolic BP >= 220 mmHg

• hypotension

• patient/cardiologist stops the exam

Normal LV response to stress:

• decreased volume and size

• increased thickening

Normal regional response:

post stress hyperkinesis

ischemic regional response:

post stress hypokinesis

Normal global response:

• increased EDV

• decreased ESV

• increased EF

ischemic global response:

• Increased EDV

• Increased ESV

• decreased EF

How do you calculate the double product?

(HR x systolic BP) / 100

What supine bike stress echo usually has a ___ response than TMSE

lower HR and higher BP

SBSE is known for its assessment of what?

viability and diastolic

Normal regional response for SBSE:

post stress hyperkinesis

Ischemic regional response for SBSE:

post stress hypokinesis

Normal global response for SBSE:

• small increase in EDV

• decrease ESV

• modest increase in EF

Ischemic global response for SBSE:

• Increase in EDV

• increase in ESV

• decrease in EF

PHARMACOLOGICAL SE/DSE