Chapter Five: Clinical Exercise Testing and Interpretation
Explain where a doctor should be while clinical exercise testing is occuring?
"in the immediate vicinity...and available for emergencies"
List criterion for confirming a maximal effort during a GXT.
- A plateau in VO2 (or failure to increase VO2 by 150mL/min) with increase in workload. - Failure of HR to increase with increases in workload - A post-exercise venous lactate concentration > 8.0mmol/L - A rating of perceived exertion (RPE) at peak exercise > 17 on the 6-20 scale or >7 on the 0-10 scale - A peak RER > 1.10. Peak RER is perhaps the most accurate and objective noninvasive indicator of subject effort during a GXT.
What are absolute contraindications for symptom-limited maximal exercise testing?
- Acute myocardial infarction within 2 days - Ongoing unstable angina - Uncontrolled cardiac arrhythmia with hemodynamic compromise - Active endocarditis - Symptomatic severe aortic stenosis - Decompensated heart failure - Acute pulmonary embolism, pulmonary infarction, or deep venous thrombosis - Acute myocarditis or pericarditis - Acute aortic dissection - Physical disability that precludes safe and adequate testing
Concerning DBP during exercise:
- EXERTIONAL ISCHEMIA = DBP > 90 OR > 10 increase from pretest value - RELATIVE INDICATION TO STOP A TEST = DBP > 115
How do you describe and/or measure a patient's exercise capacity?
- Estimated peak METs - VO2peak
What can cardiopulmonary exercise testing can get accurate measurements of?
- Exercise Capacity - Prognosis & Timing of Cardiac Transplantation for Heart Failure Patients - Differential Diagnosis for Cardiovascular and Respiratory Disease - Cardiac or Pulmonary Etiology for Dyspnea - Variables: VO2peak, VE-VCO2 slope, VAT, oxygen pulse, slope of the change in work rate to change in VO2, oxygen uptake efficiency slope, partial pressure of end-tidal CO2, breathing reserve, RER
What are causes of false negative symptom-limited maximal exercise test results for the diagnosis of ischemic heart disease?
- Failure to reach an ischemic threshold - Monitoring an insufficient number of leads to detect ECG changes - Failure to recognize non-ECG signs and symptoms that may be associated with underlying CVD (e.g., exertional hypotension) - Angiographically significant CVD compensated by collateral circulation - Musculoskeletal limitations to exercise preceding cardiac abnormalities - Technical or observer error
What are other names for a clinical exercise test?
- Graded exercise test (GXT) - Exercise tolerance test (ETT)
What variables are monitored during clinical exercise testing?
- HR - ECG (Repolarization changes) - Cardiac Rhythm - BP - Perceived Exertion - Expired Gases - Oxygen Saturation - Arterial Blood Gases - Clinical Signs & Patient-Reported Symptoms suggestive of myocardial ischemia, inadequate blood perfusion, inadequate gas diffusion, and limitations in pulmonary ventilation - Light-headedness, Dyspnea, Claudication, Angina, Fatigue
What should you consider when interpreting the clinical exercise test?
- Heart Rate Response - Blood Pressure Response - Rate-Pressure Product - Electrocardiogram - Symptoms - Exercise Capacity - CPET
What are relative contraindications to symptom-limited maximal exercise testing>
- Known obstructive left main coronary artery stenosis - Moderate to severe aortic stenosis with uncertain relationship to symptoms - Tachyarrythmias with uncontrolled ventricular rates - Acquired advanced or complete heart block - Recent stroke or transient ischemia attack - Mental impairment with limited ability to cooperate - Resting hypertension with systolic > 200mmHg or diastolic > 110mmHg -Uncorrected medical conditions, such as significant anemia, important electrolyte imbalance, and hyperthyroidism
What can alter pulse oximetry readings?
- Low pulse wave - Dyshemoglobinemias (hemoglobin abnormalities) - Low oxygen saturation - Dark skin tones - Nail polish - Acrylic nails - Movement during exercise
What are relative indications for terminating a symptom-limited maximal exercise test?
- Marked ST displacement (horizontal or downsloping of >2mm, measured 60 to 80ms after the J point in a patient with suspected ischemia) - Drop in systolic blood pressure > 10mmHg (persistently below baseline) despite an increase in workload, in the absence of other evidence of ischemia - Increasing chest pain - Fatigue, shortness of breath, wheezing, leg cramps, or claudication - Arrhythmias other than sustained ventricular tachycardia, including multifocal ectopy, ventricular triplets, supraventricular tachycardia, and brachyarrhythmias that have the potential to become more complex or to interfere with hemodynamic stability - Exaggerated hypertensive response (systolic blood pressure > 250mmHg or diastolic blood pressure > 115mmHg) - Development of bundle-branch block that cannot be distinguished from ventricular tachycardia - SpO2 < 80%
What other tests can be coupled with exercise testing?
- Myocardial perfusion imaging (nuclear stress test) - Echocardiography
What is the normal response of the ECG during exercise?
- P-wave: increased magnitude among inferior leads - PR segment: shortens and slopes downward among inferior leads - QRS: duration decreases, septal Q-waves increase among lateral leads, R waves decrease, and S waves increase among inferior leads - J point (J junction): depresses below isoelectric line with upsloping ST segments that reach the isoelectric lie within 80ms - T-wave: decreases amplitude in early exercise, returns to prexercise amplitude at higher exercise intensity, and may exceed preexercise amplitude in recovery - QT interval: absolute QT interval decreases. THE QT interval corrected for HR increases with early exercise and then decreases at higher HRs.
What are other indications for clinical exercise testing?
- Pulmonary disease - Exercise intolerance and unexplained dyspnea - Exercise -induced bronchoconstriction - Exercise-induced arrhythmias - Pacemaker or Heart Rate response to exercise - Preoperative risk evaluation - Claudication in peripheral arterial disease - Disability evaluation - Physical activity counseling
What is a hypertensive BP response?
- RELATIVE INDICATION to stop a test = SBP > 250 - EXAGGERATED RESPONSE = SBP > 210 (men) and 190 (women) - FUTURE RESTING HYPERTENSION = increase in SBP > 140 above pretest value or peak SBP > 250
List additional data that can be provided from a CPET with expired gas analysis:
- Respiratory Exchange Ratio (RER) - Ventilatory-derived anaerobic threshold (VAT) - Rate of change of minute ventilation (volume of expired air per unit time) to change in volume of carbon dioxide (VCO2) during exercise
What are considerations that may necessitate adjunctive imaging when the indication is the assessment of ischemic heart disease?
- Resting ST-segment depression > 1.0 mm - Ventricular paced rhythm - Left ventricular hypertrophy with repolarization abnormalities - Left bundle-branch block - Leads V1 through V3 will not be interpretable with right bundle-branch block - Wolff-Parkinson-White - Digitalis therapy
What is a post-exercise BP response?
- SBP is returns to pretest or lower levels by 6 minutes of recovery - a delay in recovery is related to ischemic abnormalities and poor prognosis
What are absolute indications for terminating a symptom-limited maximal exercise test?
- ST elevation (>1.0mm) in leads without preexisting Qwaves because of prior MI (other than aVR, aVL, or V1) - Drop in systolic blood pressure of >10mmHg, despite an increase in workload, when accompanied by other evidence of ischemia - Moderate-to-severe angina - Central nervous system symptoms (e.g., ataxia, dizziness, or near syncope) - Signs of poor perfusion (cyanosis or pallor) - Sustained ventricular tachycardia or other arrhythmia, including second- or third-degree atrioventricular block, that interferes with normal maintenance of cardiac output during exercise - Technical difficulties monitoring the ECG or systolic blood pressure - The subject's request to stop
What are causes of false positive symptom-limited maximal exercise test results for the diagnosis of ischemic heart disease?
- ST-segment depression > 1.0mm at rest - Left ventricular hypertrophy - Accelerated conduction defects (e.g., Wolff-Parkinson-White syndrome) - Digtalis therapy - Nonischemic cardiomyopathy - Hypokalemia - Vasoregulatory abnormalities - Mitral valve prolapse - Pericardial disorders - Technical or observer error - Coronary spasm - Anemia
List the sensitivity, specificity, and predictive value of symptom-limited maximal exercise testing for the diagnosis of ischemic heart disease (IHD):
- Sensitivity = [TP / (TP + FN)] x 100 The percentage of patients with IHD who have a positive test - Specificity = [TN / (FP + TN)] x 100 The percentage of patients wihtout IHD who have a negative test - Positive Predictive Value = [TP/ (TP + FP)] x 100 The percentage of positive tests that correctly identify patients with IHD - Negative Predictive Value = [TN / (TN + FN)] x 100 The percentage of negative tests that correctly identify patients without IHD
What factors determine the diagnostic value of exercise testing?
- Sensitivity and Specificity - Prevalence of IHD in population tested
If you are suspicious of angina pectoris, what should you be noting?
- Timing - Character - Magnitude - Resolution
What are abnormal responses of the ST segment during exercise?
- To be clinically meaningful, ST-segment depression or elevation should be present in at least three consecutive cardiac cycles within the same lead. The level of the ST segment should be compared to the end of the PR segment. Automated computer-averaged complexes should be visually confirmed. - Horizontal or downsloping ST-segment depression > 1mm at 80ms after the J point is a strong indicator of myocardial ischemia. - Clinically significant ST-segment depression that occurs during postexercise recovery is an indicator of myocardial ischemia - ST-segment depression at a low workload or low rate-pressure product is associated with worse prognosis and increased likelihood for multivessel disease - When ST-segment depression is present in the upright resting ECG, only additional ST-segment depression during exercise is considered for ischemia - When ST-segment elevation is present in the upright resting ECG, only additional ST-segment depression below the isoelectric line during exercise is considered for ischemia - Upsloping ST-segment depression > 2mm at 80ms after the J point may represent myocardial ischemia, especially in the presence of angina. However, this response has a low positive predictive value; it is often categorized as equivocal - Among patients after myocardial infarction (MI), exercise-induced ST-segment elevation (>1mm or >0.1mV for 60ms) in leads with Q waves is an abnormal response and may represent reversible ischemia or wall motion abnormalities - Among patients without prior MI, exercise-induced ST-segment elevation most often represents transient combined endocardial and subepicardial ischemia but may also be due to acute coronary spasm - Repolarization changes (ST-Segment depression or T-wave inversion) that normalize with exercise may represent exercise-induced myocardial ischemia but is considered a normal response in young subjects with early repolarization on the resting ECG
What are measures of arterial oxygen saturation?
- [Gold Standard] Measurement of arterial blood gases, providing the partial pressure of arterial oxygen (PaO2) and partial pressure of carbon dioxide in arterial blood (PaCO2) - Pulse Oximetry
What are reasons to do field walking tests such as the 6-minute walk test or endurance shuttle walk tests?
- a better representation of a patient's ability to perform ADLs since they are self-electing their walking pace - minimal cost and simple testing - measurements of exercise capacity, estimate prognosis, and evaluate responses to treatment
What is a hypotensive BP response?
- decrease below pretest resting value - more than 10 decrease (especially after a slight increase) can indicate myocardial ischemia, left ventricular dysfunction, and an increased risk of subsequent cardiac events
What does the Duke Treadmill Score/Nomogram consider? And what do they relate the score to?
- exercise capacity - magnitude of ST-segment depression - presence and severity of angina pectoris - chronotropic incompetence and abnormal HR recovery The calculated score is related to annual and 5-year survival rates and allows the categorization of patients into low-, moderate-, and high-risk subgroups.
What are the cognitive skills required to competently supervise clinical exercise tests?
- knowledge of appropriate indications for exercise testing - knowledge of alternative physiologic cardiovascular tests - knowledge of appropriate contraindications, risks, ad risk assessment of testing - knowledge to promptly recognize and treat complications of exercise testing - competence in cardiopulmonary resuscitation and successful completion of an AHA-sponsored course in advanced cardiovascular life support and renewal on a regular basis - knowledge of various exercise protocols and indications for each - knowledge of basic cardiovascular and exercise physiology including hemodynamic response to exercise - knowledge of cardiovascular drugs and how they can affect exercise performance, hemodynamics, and the electrocardiogram - knowledge of the effects of age and disease on hemodynamic and the electrocradiographic response to exercise - knowledge of principles and details of exercise testing including proper lead placement and skin preparation - knowledge of endpoints of exercise testing and indications to terminate exercise testing - 50 to 200 supervised exercise tests for independent practice - 25 to 50 supervised exercise test for maintenance
Clinical exercise testing with ECG should not happen in the following cases:
- low pretest probability of IHD - high pretest probability of IHD - left ventricular hypertrophy with ST-segment depression - Wolff-Parkinson-White - ventricualr pacing - >1mm of ST-segment depression on resting ECG - left bundle branch block
What causes a greater response in BP during exercise?
- male population - age - patients on casodialaters, calcium channel blockers, angiotensin-converting enzyme inhibitors, and apha-and-beta-adrenergic blockers.
What decrease exercise testing sensitivity?
- myocardial stress - medications that attenuate the cardiac demand to exercise or reduce myocardial ischemia (Beta Blockers, nitrates, calcium channel blockers) - insufficient ECG lead monitoring (left ventricular hypertrophy, left bundle-branch block, and pre-excitation syndrome limit the ability to interpret exercise-induced ST segment changes)
What classifies an exercise test as negative for IHD detection?
- myocardial stress >85% of predicted HRmax - Peak rate-pressure product > 25,000 mmHg/min
What can echocardiographic examination measure?
- wall motion - wall thickness - valve function (Ejection Fracture)
What are the three indications for clinical exercise testing?
1. diagnosis (presence of disease or abnormal physiologic response) 2. prognosis (risk for an adverse event) 3. evaluation of the physiologic response to exercise (blood pressure and peak exercise capacity)
[Fill in the Blank] The cycle ergometer in a __________--__________% lower score than the treadmill due to regional muscle fatigue.
5-20%
How long should total exercise duration be when performing a sign- and symptom- limited maximal exercise test?
6-12 minutes
What are cases when it is ideal to perform exercise testing in an ER?
A. Patients who are at low-to-intermediate risk for IHD and have been appropriately screened by a physician B. To improve the accuracy of diagnosing acute coronary syndrome C. Reduce the cost of care by reducing the need for additional tests and length of stay
Is sustained ventricular tachycardia during exercise an (absolute or relative) criterion to terminate a test?
Absolute Criterion
If someone has ventricular ectopy during exercise, what are they at increased risk of?
Cardiac arrest
If someone cannot achieve an age-predicted HRmax > 85% in the presence of maximal effort, what does that indicate?
Chronotropic incompetence (associated with morbidity and mortality)
What does myocardial oxygen uptake have a linear relationship with?
Coronary blood flow and exercise intensity
Describe the linear relationship of myocardial oxygen uptake and coronary blood flow and exercise intensity.
Coronary blood flow increases due to increased myocardial oxygen demand as a result of increases in HR and myocardial contractility. IF coronary blood flow supply is impaired, which can occur in obstructive IHD, myocardial ischemia signs and symptoms will become present.
What is the most accurate measure of exercise capacity?
Direct measurement of VO2 (via analysis of expired gas during CPET)
What is the most widely accepted and used of the clinical exercise testing prognostic?
Duke Treadmill Score/Nomogram
When is exercise testing appropriate in a chest pain unit?
For patients (1) whose symptoms have resolved, (2) have a normal ECG, and (3) had no change in enzymes reflecting cardiac muscle damage
What is rate pressure product? What is the normal range for peak rate-presure product?
HR x systolic BP, used to evaluate myocardial oxygen uptake 25000-40,000 mmHg x beats/minute
What is the best time to perform the echocardiography during an exercise test?
Immediately after the exercise test *Patient needs to lay on their LEFT SIDE to open the echocardiographic window of the heart.
What is a blunted BP response?
In patients with a limited ability to augment cardiac output (Q), the response of SBP during exercise will be slower compared to normal
If someone's heart rate does not decrease 12bpm in the first minute post-exercise or 22bpm in the second minute post-exercise, what does it indicate?
Increased risk of mortality and IHD
What is a dysrhythmia that increases in frequency or complexity (especially in regards to exercise) associated with?
Ischemia or hemodynamic instability
Exercise-induced angina (especially with ST-segment depression) puts someone at a risk of?
Ischemic Heart Disease (IHD)
What distinguishes a cardiopulmonary exercise test (exercise metabolic test) from other exercise tests?
It includes the analysis of expired gases during exercise.
Does diastolic blood pressure typically change during exercise?
No
Who is the Duke Treadmill Score/Nomogram appropriate for?
Patients with or without a history of IHD being considered for coronary angiography without a history of MI or revascularization procedure
Why is a cool-down in clinical exercise testing important?
Support of venous return and hemodynamic stability
[Fill in the Blank] Either absolute or age- and gender- normalized exercise capacity is highly related to ______________________.
Survival
What is the most widely used submaximal testing protocol for clinical exercise testing in the US?
The Bruce Treadmill Protocol
What is conditional probability??
The probability of identifying a patient with IHD given the probability of IHD in the underlying population
[Fill in the Blank] The __________________ is the most common testing mode in the US, while the ________________ ___________________ is the most common in Europe.
Treadmill - US Cycle Ergometer - Europe
True or False: Measuring exercise capacity is important because it is relative to the prognosis of patients with Heart Failure or Cardiovascular Disease.
True
[True or False] Arm ergometry, Dual-action ergometry, and Seated steeping ergometry may be ideal exercise testing modes for patients with balance issues, amputation, extreme obesity, and other mobility deficiencies.
True
[True or False] Symptoms consistent with myocardial ischemia (angina/dyspnea) or hemodynamic instability (light-headedness) should be noted and correlated with ECG, HR, and BP abnormalities.
True
What is the best measurement of exercise capacity?
Via respiratory gas analysis using open circuit indirect calorimetry for the determination of maximal volume of oxygen consumed per unit of time (VO2max)
What is ischemic threshold?
When myocardial ischemia becomes present during exercise.
What is the predictive value of clinical exercise testing?
a measure of how accurate a test result (positive or negative) correctly identifies the presence or absence of IHD in patients and is calculated from sensitivity and specificity
If someone has stable chest pain, how should you test them?
a symptom limited maximal exercise test with electrocardiographic monitoring
What is the most common diagnostic indication for clinical exercise testing?
assessment of symptoms suggestive of ischemic heart disease [IHD]
Does HR increase or decrease with age?
decrease
[Fill in the Blank] A high exercise ______________________ is indicative of a high peak Q and therefore suggests the absence of serious limitations of let ventricular function.
exercise capacity
What is a healthy HR response to exercise?
increases of ~ 10bpm per 1 MET
What is a healthy systolic blood pressure response to exercise?
increases of ~ 10mmHg per 1 MET
[Fill in the blank] There is an ___________ relationship between cardiorespiratory fitness measured from an exercise test and the risk of mortality amount apparently healthy individuals; patients at risk for IHD; and those with diagnosed heart disease, heart failure, and lung disease.
inverse
[Fill in the Blank] During a clinical exercise test, patients are _______________________________ while performing _________________________ (most common) or constant work exercise using standardized protocols and procedures and typically using a treadmill or a stationary cycle ergometer.
monitored incremental
What is it a sign of if you have deterioration in the regional wall motion with exercise?
myocardial ischemia
What is the positive predictive value?
percentage of individuals identified by the test as positive who actually have the diagnosis
What is negative predictive value?
percentage of individuals with a negative test who are free of IHD
What can myocardial perfusion imaging help measure?
radioisotopes can indicate coronary blood flow and ventricular function, starting the 'ischemic cascade'
What is specificity?
the ability to correctly identify patients who do not have IHD
What is sensitivity?
the ability to positively identify patients who truly have IHD
What is a true negative test?
the test is negative for myocardial ischemia and the patient is free of IHD
What is a false negative?
the test is negative for myocardial ischemia but the patient truly has IHD
What is a true positive?
the test is positive for myocardial ischemia and hte patient truly has IHD
What is a false positive test?
the test is positive for myocardial ischemia but the patient does not have IHD
