UNIT 1 LESSON 1 : STRESS ECHOCARDIOGRAPHY IN ISCHEMIC HEART DISEASE

List the 4 clinical significances of stress echocardiography.

• Non-invasive

• Combines ECG and echocardiography, making it more specific and sensitive

• False positives can occur

• Detects regional wall-motion abnormalities (RWMAs)

What is myocardial ischemia?

Myocardial ischemia occurs when the coronary arteries become narrowed, blocked, or unable to deliver enough oxygen-rich blood to the heart.

list the 4 possible causes for myocardial ischemia

• Atherosclerosis

• Blood clots

• Coronary artery spasms

• Any other condition that restricts blood supply

What is the ischemic cascade?

The sequence of events that occurs after the onset of myocardial ischemia.

List the 6 steps of the ischemic cascade in order.

• Coronary demand-supply mismatch

• Cellular metabolic derangements

• Diastolic dysfunction

• Systolic dysfunction

• Ischemic ECG changes

• Anginal symptoms

List the 3 abnormal wall-motion findings that may occur with myocardial ischemia.

• Hypokinesia

• Akinesia

• Dyskinesia

During the ischemic cascade, when are RWMAs, ECG changes, and angina usually seen?

RWMAs can be detected before ECG changes, while angina occurs last. ECG changes may sometimes occur after exercise has stopped during the recovery period.

List the 3 reasons ECG changes may be seen before you visibly detect a RWMA in clinical practice.

1. Image quality is suboptimal

2. Ischemia is mild or transient

3. The affected area is small

The ECG is more sensitive but less specific.

List the 5 clinical indications for stress echocardiography.

• Symptoms of myocardial ischemia

• Chest pain without ACS or MI

• Recent ACS without angiography

• Stable CAD or change in clinical status

• Suspected risk for CAD before noncardiac surgery

List the 8 absolute contraindications for stress echocardiography.

• Acute MI within 2 days

• Unstable angina

• Uncontrolled cardiac arrhythmias

• Symptomatic severe aortic stenosis

• Uncontrolled symptomatic heart failure

• Acute pulmonary embolism

• Acute myocarditis, pericarditis, or infective endocarditis

• Acute aortic dissection

List the 8 relative contraindications for stress echocardiography.

• Left main coronary artery stenosis

• Moderate stenotic valvular heart disease

• Electrolyte abnormalities

• Severe arterial hypertension

• Tachyarrhythmias or bradyarrhythmias

• HCM or other forms of outflow-tract obstruction

• Mental or physical impairment causing inability to exercise

• High-degree AV block

List the 7 pieces of equipment needed for an exercise stress echo.

• Ultrasound machine

• ECG

• Treadmill

• Synapse

• Ultrasound bed

• BP cuff

• Code cart

List the 3 personnel requirements for an exercise stress echo.

• Physician readily available

• Qualified monitor, such as a stress tech or RN

• Stress-trained sonographer

List the 5 things that should be reviewed or completed when preparing the patient before the stress echo.

• Patient should be NPO for more than 3 hours

• Review patient history and CAD risk factors/history of MI, PTCA, or CABG

• Review prior relevant tests and medications

• Know the indication for the exam

• Obtain informed consent

List the 3 things performed immediately before beginning the stress exam.

• Place a 12-lead ECG

• Obtain resting BP and ECG

• Start an IV if Definity contrast is needed

List the 4 types of exercise stress testing.

• Treadmill

• Supine bicycle

• Upright bicycle

• Isometric exercise

What is the formula for maximal heart rate?

Maximal HR = 220 − age

What percentage of the maximal heart rate is the target heart rate, and what should the patient achieve?

The target HR is 85% of the maximal HR. The patient should achieve at least their target HR, and images are taken at target HR.

What is the target heart rate for a 22-year-old?

Max HR:

220 − 22 = 198 bpm

Target:

198 × 0.85 = approximately 168 bpm

List the 3 conditions that should be ruled out before beginning the Aurora exercise stress echo protocol.

• Significant valvular disease, especially severe AS

• Aortic aneurysm

• Severe pulmonary hypertension

List the 5 baseline views obtained before exercise.

• Apical 4-chamber

• Apical 2-chamber

• Apical 3-chamber

• PLAX

• Mid-PSAX

Obtain one-beat clips with or without contrast.

List the 3 things that are done after exercise during the Aurora stress echo protocol.

• Obtain post-exercise images in less than 60 seconds

• Continuously capture the same 5 views

• If RWMAs are present, continue imaging until they normalize

List the 7 abnormalities that should be assessed during the mini echo before baseline images.

• Valvular abnormalities

• Indications of heart failure

• HCM or another obstructive disease

• CAD

• ECG abnormalities

• Acute PE

• Aortic dissection

List the 4 things quickly assessed in the PLAX and PSAX during the mini echo.

• Effusion

• Wall thickness

• Function/CAD assessment

• Sweep with color through all valves

List the 3 things quickly assessed from the apical views during the mini echo.

• Function

• Valvular abnormalities

• CW/PW Doppler if needed

List the first 4 stages of the standard Bruce protocol with their grade, speed, and total time.

• Stage 1: 10% grade, 1.7 mph, 3 minutes

• Stage 2: 12% grade, 2.5 mph, 6 minutes

• Stage 3: 14% grade, 3.4 mph, 9 minutes

• Stage 4: 16% grade, 4.2 mph, 12 minutes

List the last 3 stages of the standard Bruce protocol with their grade, speed, and total time.

• Stage 5: 18% grade, 5.0 mph, 15 minutes

• Stage 6: 20% grade, 5.5 mph, 18 minutes

• Stage 7: 22% grade, 6.0 mph, 21 minutes

What is 1 MET equal to?

1 MET = 3.5 mL O₂/kg/min.

List the 3 main features of the Modified Bruce protocol.

• Lower initial workload

• Fewer stages

• Safer for patients with low exercise tolerance

List the first 3 stages of the Modified Bruce protocol.

• Stage I: 1.7 mph, 0% grade, 3 minutes — PowerPoint lists 2.9 METs

• Stage II: 1.7 mph, 5% grade, 3 minutes — 3.7 METs

• Stage III: 1.7 mph, 10% grade, 3 minutes — PowerPoint lists 9 METs and states this matches Stage 1 of the standard Bruce protocol

List the last 4 stages of the Modified Bruce protocol.

• Stage IV: 2.5 mph, 12% grade, 3 minutes

• Stage V: 3.4 mph, 14% grade, 3 minutes

• Stage VI: 4.2 mph, 16% grade, 3 minutes

• Stage VII: 5.0 mph, 18% grade, 3 minutes

List the 3 ECG territories and the leads used to identify infarction in each territory.

• Anterior: V1–V4

  • Anteroseptal: V1–V2

  • Anterolateral: V3–V4

• Lateral: I and aVL

• Inferior: II, III, aVF

List the 3 ECG findings and what each one indicates.

• Prominent Q wave = necrosis

• ST depression = subendocardial infarct

• ST elevation = acute injury

List the 4 abnormal ST-change examples shown in the PowerPoint and what each represents.

• Point A: Horizontal ST depression

• Point B: Down-sloping ST depression

• Point C: ST elevation greater than 1 mm — indicative of myocardial ischemia

• Point D: Upsloping ST depression less than 1.5 mm — does not meet criteria for ischemia

List the 3 factors included in the Duke Treadmill Score and state what the score predicts.

1. Functional capacity

2. Exertional angina

3. Ischemic ECG changes

It predicts the risk of CAD and future cardiac events based on the stress-test results.

What is the normal regional response to exercise stress?

Hyperkinesis after exercise compared with rest.

List the 2 global findings of a normal stress response.

• Decrease in ESV

• Increase in EF by at least 5%

What is the annual rate of cardiac death or nonfatal MI after a normal stress echo?

Less than 1% per year.

List the 4 important characteristics or uses of bicycle/treadmill exercise stress

• Preserves the integrity of the electromechanical response

• Preferred in patients who can achieve adequate exercise with known or suspected CAD

• Bicycle stress is preferred for assessing diastolic function

• Increases myocardial oxygen demand

List the 5 hemodynamic responses to exercise.

• Heart rate increases

• Stroke volume increases through the Frank-Starling mechanism

• Systolic BP increases by approximately 50%

• Contractility increases

• Myocardial blood flow increases

What is a regional ischemic response during a stress echo?

A reduction in wall motion compared with resting function in the same region or compared with other regions that have normal blood supply.

List the 2 findings of a global ischemic response.

• Increase in EDV and/or ESV

• Decrease in EF with left-main or multivessel disease

What is tardokinesis, and what can it result in?

Ischemia may delay the onset of contraction, called tardokinesis, resulting in post-systolic contraction or dyssynchrony. Evaluate the images frame by frame for delayed contraction

List the 2 other conditions given in the PowerPoint that can cause delayed contraction.

• LBBB

• RV pacing

List the 5 rest-to-stress wall-motion responses and what each one means.

• Normal at rest → Hyperdynamic with stress = Normal

• Normal at rest → Unchanged or worse with stress = Ischemia

• Abnormal at rest → Worse with stress = Ischemia

• Abnormal at rest → Unchanged with stress = Infarct

• Akinetic at rest → Improves or worsens with stress = Viable myocardium

How many segments are typically used for the Wall Motion Score Index, and when may 17 segments be used?

A 16-segment model is typically used. A 17-segment model may be used when evaluating the apical cap to compare with another imaging modality.

List the 5 wall-motion scores used for WMSI.

• Normal or hyperkinetic

• Hypokinetic

• Akinetic

• Dyskinetic

• Aneurysmal

What is the formula for Wall Motion Score Index?

WMSI = sum of the segment scores ÷ total number of segments

List the 3 findings used to distinguish normal, hypokinetic, and akinetic wall motion.

• Normal: Normal inward motion and systolic thickening; endocardial thickening >40%

• Hypokinetic: Reduced inward motion and thickening; endocardial thickening <30%

• Akinetic: No inward motion or thickening; endocardial thickening <10%

List the 2 characteristics of dyskinetic wall motion.

• Paradoxical thinning or outward motion during systole

• Usually associated with thin wall segments and scarring

List the 2 characteristics of aneurysmal wall motion.

• Dilation and outward movement throughout the cardiac cycle

• Associated with thin wall segments and diastolic deformation

List the 6 conditions that may cause RWMAs even without significant angiographic coronary stenosis.

• Microvascular abnormalities

• Endothelial dysfunction

• Vasospasm

• Small-vessel disease

• Amyloidosis

• Apical ballooning syndrome

List the 2 additional conditions associated with false-positive wall-motion findings on the next slide.

• DCM

• LBBB/postoperative state

List the 4 causes of a false-positive ECG given

• LVH

• Women older than 40

• LBBB, RBBB, or pacemaker

• Digoxin

List the 4 causes of a false-negative stress echo.

• Small-vessel disease

• Inadequate workload or heart rate

• Rapid resolution of RWMAs before images are captured

• Intermediate stenosis of 50%–70%

List the 7 limitations of stress echocardiography imaging.

• Poor imaging windows

• User dependent

• Respiratory interference

• Translational motion

• Difficulty acquiring identical views

• Time after exercise

• Medications such as beta blockers

List the first 5 stages of the bicycle stress protocol with the watts, METs, and total time.

1. Stage 1: 25 watts, 2.4 METs, 2 minutes

2. Stage 2: 50 watts, 3.7 METs, 4 minutes

3. Stage 3: 75 watts, 4.9 METs, 6 minutes

4. Stage 4: 100 watts, 6.1 METs, 8 minutes

5. Stage 5: 125 watts, 7.3 METs, 10 minutes

Each stage lasts 2 minutes.

List the last 5 stages of the bicycle stress protocol with the watts, METs, and total time.

1. Stage 6: 150 watts, 8.6 METs, 12 minutes

2. Stage 7: 175 watts, 9.8 METs, 14 minutes

3. Stage 8: 200 watts, 11.0 METs, 16 minutes

4. Stage 9: 225 watts, 12.2 METs, 18 minutes

5. Stage 10: 250 watts, 13.5 METs, 20 minutes

Each stage lasts 2 minutes.

List the 3 advantages of bicycle stress testing.

• Continuous real-time imaging — helps catch transient RWMAs or filling changes

• More controlled workload — resistance can be increased gradually and precisely

• Useful for patients with exercise limitations — such as neurologic, orthopedic, or balance problems

List the 4 diastolic measurements that can be obtained during bicycle stress.

1. E/e′

2. Mitral E/A

3. Tissue Doppler

4. TR velocity

These can be measured at any stage rather than only after exercise.

List the 4 diagnostic endpoints shown for exercise stress testing.

• Workload at least 80% predicted for age and sex

• Marked ECG positivity

• Obvious echo positivity

• Severe chest pain

List the 5 causes for stopping the stress test shown on the slide.

• Intolerable symptoms

• Muscular exhaustion

• Severe hypertension — 220/120 mmHg

• Symptomatic hypotension

• Arrhythmias such as SVT, new AF, or frequent/complex ventricular ectopy

List the 3 major findings of an abnormal stress test shown on the slide.

• Symptoms such as angina, syncope/near-syncope, or fatigue at a low workload

• Ischemia with a new or worsening RWMA

• Arrhythmias

List the 3 additional abnormalities that may develop during stress testing.

• E/septal e′ greater than 15

• Pulmonary hypertension

• Ischemic mitral regurgitation

What is an isometric handgrip stress test?

It is a low-level afterload stress test in which the patient squeezes a device at a sustained effort while the sonographer obtains images.

List the 4 things an isometric handgrip test can evaluate.

• Diastolic reserve

• Mitral regurgitation

• Subtle hemodynamic changes

• RWMAs, although it is less sensitive than treadmill or bicycle stress

What is the physiologic sequence that occurs during sustained isometric contraction?

Sustained isometric contraction → sympathetic activation → peripheral vasoconstriction

List the 3 things that increase during an isometric stress test.

• Systemic vascular resistance

• Blood pressure

• Heart rate

List the 7 cardiac responses to isometric stress.

• LV pumps against higher resistance

• Wall stress increases

• Myocardial oxygen demand increases

• Relaxation becomes more impaired when diastolic dysfunction is present

• E/e′ increases

• TR velocity increases

• Mitral regurgitation increases

List the 5 reasons for routine termination of an exercise stress test.

• Target HR or double product achieved

• Fatigue

• Shortness of breath

• Unable to complete exercise

• Angina greater than 7

List the 9 abnormal findings that may require termination of the stress test.

• Moderate-to-severe angina

• Severe shortness of breath

• O₂ saturation below 90% or a drop greater than 10% from baseline

• Decrease in SBP greater than 10 mmHg or severe hypertension with SBP greater than 250 mmHg

• Evidence of hypoperfusion

• Sustained VT, SVT, heart block, bradyarrhythmias, NSVT, or BBB

• ST elevation greater than 1 mm or ST depression greater than 2 mm

• Development of RWMAs or global hypokinesis

• Development of severe pulmonary hypertension with PAP greater than 60 mmHg

List the 3 things that should be reported during the baseline regional wall-motion assessment.

• Number, location, and severity of regional or global wall-motion abnormalities

• Presence of wall thinning or increased thickness

• Assessment of EF

List the 6 things that should be reported during the stress regional wall-motion assessment.

• Number, location, and severity of regional or global wall-motion abnormalities

• EF response to stress

• End-systolic size response to stress

• Response during various stages of stress, especially if resting RWMAs are present

• Adequacy of imaging

• UEA use, including the agent and dose

List the 3 things that should be documented about the type and adequacy of the stress test.

• Type of stress-testing protocol and drug doses if pharmacologic stress is used

• Adequacy of the stress/workload for the patient's age and sex

• Whether target HR was achieved during dobutamine stress testing

What should be stated if ischemia is not detected but the stress level was inadequate?

The report should state that inadequate stress may reduce the sensitivity for detecting ischemia.

List the 3 things that should be documented at each stage of the stress test

• Heart rate and blood pressure

• ECG findings, including ischemia or arrhythmias

• Cardiac symptoms

List the 3 additional reporting recommendations shown on the slide.

• Include a diagram or graphic of wall motion at rest and with stress

• Describe additional resting findings if the patient has not already had a TTE

• For exertional dyspnea, E/e′, RV systolic pressure, and/or oxygen saturation at rest and stress may be helpful

List the 4 possible overall stress-echo interpretations.

• Normal

• Ischemia

• Fixed wall-motion abnormality

• Combination of findings

When should a UEA be used during stress echocardiography, and when should it be given?

Use a UEA for LV opacification when 2 or more LV segments cannot be adequately visualized. It should be used during both baseline/resting and stress imaging.

Why is visualization of all LV wall segments and coronary territories important during stress echo?

It is optimal for evaluating coronary disease and ischemic changes.

List the 6 other clinical applications for UEAs.

• LV volumes, LVEF, and RWMAs

• Intracardiac thrombi

• Intracardiac masses

• Apical HCM

• Post-MI complications

• TEE left atrial appendage imaging

List the 3 common contrast artifacts.

• Attenuation

• Swirling

• Apical dropout

List the 4 best imaging practices when using contrast.

• Low MI, less than approximately 0.2–0.3

• Low gain

• Place the focal position in the far field and adjust toward the apex when needed

• Slow infusion rate

List the 4 uses of saline contrast

• Evaluate right-to-left intracardiac shunts

• Evaluate persistent left SVC or unroofed coronary sinus using a left-arm IV

• Enhance Doppler signals

• Evaluate catheter placements

What can negative contrast in the right atrium indicate?

It may indicate a left-to-right shunt.

How does bubble timing help distinguish an ASD/PFO from a pulmonary AVM?

• ASD/PFO: bubbles appear in less than 3 beats

• Pulmonary AVM: late bubbles appear after more than 5 beats