Exercise Stress Electrocardiography. Dr Bijilesh.U. Exercise is a common physiological stress used to elicit cardiovascular abnormalities not present at rest and to determine adequacy of cardiac function.
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Exercise Stress Electrocardiography
Exercise is a common physiological stress used to elicit cardiovascular abnormalities not present at rest and to determine adequacy of cardiac function.
Exercise ecg - one of the most frequent noninvasive modalities used to assess patients with suspected or proven cardiovascular disease.
Estimate likelihood & extent of CAD , the prognosis , determine functional capacity & effects of therapy.
Exercise test indications
Specific Clinical Applications
Safety and risks of exercise testing
Termination of exercise
skeletal muscle blood flow is increased
O2 extraction increases by as much as threefold
total calculated peripheral resistance decreases
systolic blood pressure, mean arterial pressure, and pulse pressure increase
- cardiac output
- peripheral AV oxygen difference
- Contractility & HR
MHR = 206 − 0.88 (age in years)
METs = Speed x [0.1 + (Grade x 1.8)] + 3.5 3.5
Calculated automatically by Device!
- Approximately 8 to 12 minutes of continuous progressive exercise
- myocardial oxygen demand elevated to patient's maximum
HR & BP responses to a
given workload > leg exercise
Peak vo2 and peak HR
- 70% of leg testing
starting at 25 – 50 watts
No caffeinated beverages or smoke 3hr before
Wear comfortable shoes and clothes.
Unusual physical exertion should be avoided
Brief history & physical examination performed
Explain risks and benefits
Informed consent is taken
12 lead ECG is recorded with electrodes at the distal extremities
Torso ECG is obtained in supine & standing position
If false +ve test is suspected, hyperventilation should be performed
Room temp should be 18 –24 C & humidity < 60%
Walking should be demonstrated to the patient
HR, BP & ECG recorded at end of each stage.
Resuscitator cart, defibrillator and appropriate cardioactive drugs should be available
right axis shift
increased voltage in inferior leads
loss of inferior Q waves
new Q waves in lead aVL
may persist with down sloping ST segments and T wave
inversion - returning to baseline after 5-10 min
Measurement of ST-Segment Displacement
PQ junction is chosen as isoelectric point
TP segment is true isoelectric point but impractical choice
Abnormal ST depression
0.1mv (1mm) or > ST depression from PQ junction with a flat ST segment slope ( <0.7-1mv /sec)
80 msec after J point (ST 80)
in 3 consecutive beats with a stable base line
When ST 80 measurement difficult at rapid heart rates > 130/mt measure at ST 60
When ST is depressed at rest- additional 0.1mv or more during exercise is considered abnormal
2. J POINT
Rapid upsloping ST segment (more than 1 mV/sec) depressed less than 1.5 mm after the J point - normal
Slow upsloping ST segment
at peak exercise
In patients with high CAD prevalence, slow up sloping ST ,depressed > 1.5mm ST 80 is considered abnormal
Horizontal ST-segment depression
Eight typical exercise ecg patterns at rest and at
at rest to positive T wave in exercise – pseudonormalisation
patients without prior MI
diagnostic or prognostic
content of test
Development of typical angina during exercise can be a useful diagnostic finding
Chest discomfort usually occurs after the onset of ST segment abnormality
Exercise-induced angina and a normal ECG requires assessment using a myocardial imaging
INDICATION FOR EXERCICE ECG FOR DIAGNOSIS . ACC/AHA Guidelines 2002
down sloping ST - involving ≥5 leads,
- ≥5 min into recovery
0-if no angina
1-if typical angina occurs during exercise
2-if angina was the reason pt stopped exercise
Specific Clinical Applications
Exercise testing is useful to determine
Functional capacity for activity prescription
Assessment of adequacy of medical therapy
Incidence cardiac events with test after MI is low
Slightly greater for symptom-limited protocols
achievement of 5 to 6 METs
70% to 80% of age-predicted maximum HR
VPCs are common during exercise test & increase with age.
Occur in 0-5% of asymptomatic subjects - no increased risk of cardiac death
Suppression of VPCs during exercise is nonspecific.
In patients with recent MI, presence of repetitive VPC is associated with increased risk of cardiac events.
Premature beats are seen in 4-10%of normal persons & 40%of patients with heart disease.
Sustained arrhythmia occur in 1-2%.
Rapid ventricular response is seen in initial stages of exercise
Effect of digitalis & beta-blockers on attenuating this can be assessed by exercise testing
1.new onset ST depression in V5 & V6, or L II or avF
2.reduced exercise capacity
3.inability to adequately increase systolic BP
more frequent with left sided than right sided
Diagnostic accuracy is less in women due to lower prevalence of CAD.
False +ve results are common during menses or preovulation, & in postmenopausal women on
athletic participation - Class IIa
Excessive HR response to low levels of
Exercise-induced hypotension & chest pain
- Favor earlier valve repair
Impaired coronary vascular reserve in a successfully dilated vessel
Maximal O2 uptake & work capacity
improved as compared with pre-operative findings.
Abnormalities that may be seen are
2.slow HR response during mild to moderate exercise
3.more prolonged time for HR to return to baseline during
Absolute Contraindications to Exercise Testing
Relative Contraindications to Exercise Testing