Post on 02-Dec-2014
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Stress Exercise Testing and
InterpretationDr. Ravinder Narwal
Type of CPX1.Max. Execise test2.Submaximal exercise testing
1. In this strategy, the patients exercise enough to achieve 70% of maximum predicted heart rate for their age (ie, 70% of 220 minus age in years).
2. This test is commonly performed prior to discharge and is followed by maximal exercise testing 6-8 weeks later (when patients aim to achieve 90% of maximum predicted heart rate)
3.Symptom-limited exercise testing1. The patients exercise soon after a cardiac event.2. A representative schedule might begin exercise at
intervals, such as 7-21 days following uncomplicated acute myocardial infarction (MI), 3-10 days following angioplasty, or 14-28 days after bypass surgery.
Indications for CPX
• General indications– Assessment of general fitness– Evaluation of dyspnea
• Evaluation of certain pulmonary disorders– COPD, including EIA– Interstitial lung disease
Indications for CPX
• Evaluation of certain cardiovascular disorders– Pulmonary vascular disorders– Coronary artery disease– Other vascular disorders
• Other general disorders– Neuromuscular disorders– Obesity– Anxiety induced hyperventilation
Exercise Testing
• Best used for :• Patients w/ signs & symptoms who are probably + for CAD
• Persons w/ multiple risk factors but who are asymptomatic
Contraindications for CPX
• General contraindications– Limiting neurological disorders– Limiting neuromuscular disorders– Limiting orthopedic disorders
Contraindications for CPX
• Cardiovascular contraindications– Acute pericarditis– CHF– Recent MI (<4 weeks)– 2nd or 3rd degree H block– Significant atrial or ventricular tachyarrhymias
Contraindications for CPX
• Uncontrolled hypertension
• Unstable angina
• Recent systemic or pulmonary embolism
• Severe aortic stenosis
• Thrombophlebitis or intracardiac thrombi
Complication of CPXCardiacBradyarrhythmiasSinusAtrioventricular junctionalVentricularAtrioventricular blockAsystoleSudden death (ventricular tachycardia/fibrillation)Myocardial infarctionHeart failureHypotension and shockNoncardiacMusculoskeletal traumaIll-defined and miscellaneousSevere fatigue sometimes persisting for days, dizziness, fainting, body aches, delayed feelings of illness
Key Points of Exercise Testing
• Manual SBP measurement (not automated) most important for safety
• Adjust to clinical history• No Age predicted Heart Rate Targets• The BORG Scale of Perceived Exertion• METs• Fit protocol to patient (RAMP)• Use standard ECG analysis/ 3 minute recovery/
use scores• Heart rate recovery • Expired Gas Analysis?
6-20 BORG BORG
SCALESCALE
6
7 Very, very light
8
9 Very light
10
11Fairly light
12
13Somewhat hard
14
15Hard
16
17Very hard
18
19Very, very hard
20
RPE
SC
ALE
0 No exertion at all 0.5 Extremely light (just noticeable) 1 Very light 2 Light 3 Somewhat hard 4 5 Hard (heavy) 6 7 Very hard 8 9 10 Extremely hard (almost maximal) * Maximal exertion
Perceived Exertion Scale (CR 10) Adapted from Borg (1998)
Symptom-Sign Limited Testing Endpoints – When to
stop! Dyspnea, fatigue, chest pain
Systolic blood pressure drop
ECG--ST changes, arrhythmias
Physician Assessment
Borg Scale (17 or greater)
Target Heart Rate
• Approximates the actual heart rate at an oxygen consumption of 65 to 75% of the predicted vo2max
How to read an Exercise ECG
Good skin prepNot one beatThree consistent complexes
Averages can helpThree minute recovery
Types of Exercise Isometric (Static)
–weight-lifting–pressure work for heart, limited cardiac output, proportional to effort
Isotonic (Dynamic)–walking, running, swimming, cycling–Flow work for heart, proportional to external work
Mixed
Problems with Age-Predicted Maximal Heart Rate
Which Regression Formula? (220 - ..5 x Age) Confounded by Beta Blockers A percent value target will be maximal for some and sub-max for others
Borg scale is better for evaluating Effort Do Not Use Target Heart Rate to Terminate the Test or as the Only Indicator of Effort or adequacy of test
Information Obtained From CPX
Monitor The Patient on CPX
• HR & BP• Anginal Scale• Dyspnea Scale• Borg’s RPE Scale• EKG monitoring - Leads I, II, V5• Patient’s subjective symptomatology
Information Obtained From CPX
– Lung function• RR• Vt and VE• Spo2• Oxygen uptake or consumption (VO2 and
vo2max• Carbon dioxide production (VCO2)• Respiratory quotient (RQ)
Information Obtained From CPX
• Cardiovascular function– Hr– B/p– ECG– O2 pulse (O2 consumption per beat)– Cardiac output– HR reserve ( 1-[HRmax –Hrrest/
Hrpred.Max – Hrrest]
Information Obtained From CPX
• Metabolic equivalents of energy expenditure (METS)
– 1 MET equals +/- 3.5 ml O2 consumption per kg of body weight per minute (at rest, all pts are at 1 MET)
• Anaerobic threshold (AT)• VD/VT• Breathing reserve (1 – [VEmax/MVV]
Oxygen Consumption During Dynamic Exercise TestingThere are Two Types to Consider:
Myocardial (MO2)–Internal, Cardiac
Ventilatory (VO2)–External, Total Body
Myocardial (MO2)
Systolic Blood Pressure x HR
SBP should rise > 40 mmHg
Drops are ominous (Exertional Hypotension)
Diastolic BP should decline
Ventilatory (VO2) Cardiac Output x a-VO2 Difference
VE x (% Inspired Air Oxygen Content - Expired Air Oxygen Content)
External Work Performed
****Direct relationship with Myocardial O2 demand and Work is altered by beta-blockers, training,...
VO2 VO2 THE FICK EQUATIONTHE FICK EQUATION
VO2 = C.O. x C(a-v)O2VO2 = C.O. x C(a-v)O2
Equipment and Personnel
Equipment and Personnel
• Equipment– Metabolic cart (breath by breath analysis)– Spirometer with computer– Pulse oximeter– Ergometer and/or treadmill– ECG recorder and monitor– B/P cuff (automated if possible)– Crash cart
Equipment
Treadmill tests
Upper arm ergometryRepetitive
lifting/weight carrying test
Devices Used for Exercise
• Ergometer (stationary bicycle)– Pro’s
• Pt. Is seated
• Work load is independent of patient weight or size
– Con’s• Slightly longer learning curve
Devices Used for Exercise
• Treadmill– Pro’s
• Minimal learning curve– Con’s
• Workload dependant upon pt size and weight• Workload varies with handgrip• Can be dangerous
WORKWORK
TREADMILLTREADMILL
WORK WORK
TIME TIME TIME TIME
WORK WORK
Why Ramp?
Individualized test Using Prior Test, history or Questionnaire
Linear increase in heart rate Improved prediction of METs Nine-minute duration for most patients Requires special Treadmill controller or manual control by operator
Types Of Testing protocols
Types Of Tests protocols
• Treadmill tests• Bruce or Ellestad - good for young folks
because the between-stage graduations of grade and speed are more aggressive
• USAFSAM or Naughton - good for older folks because of the more gradual between-stage progressions of grade and speed
Bruce Protocol GXTStage Speed Grade Dur.
I 1.7 mph 10 % 3 min
II 2.5 mph 12 % 3 min
III 3.4 mph 14 % 3 min
IV 4.2 mph 16 % 3 min
V 5.0 mph 18 % 3 min
VI 5.5 mph 20 % 3 min
Modified BruceStage Speed Grade Dur.
I 1.7 mph 0 % 3 min
II 1.7 mph 5 % 3 min
III 1.7 mph 10 % 3 min
IV 2.5 mph 12 % 3 min
V 3.4 mph 14 % 3 min
VI 4.2 mph 16 % 3 min
VII 5.0 mph 18 % 3 min
USAFSAM GXTStage Speed Grade Dur.
I 2.0 mph 0 % 3 min
II 3.3 mph 0 % 3 min
III 3.3 mph 5 % 3 min
IV 3.3 mph 10% 3 min
V 3.3 mph 15% 3 min
VI 3.3 mph 20% 3 min
Reasons To Stop The Test• Drop in BP with increases in workload• Moderate to severe angina• Ataxia, dizziness, syncope• Dysrhythmias• ST segment elevations and depressions• Hypertensive responses
CPX Testing significance HRR
Should Heart Rate Recovery be added to ET?
Long known as a indicator of fitness: perhaps better for assessing physical activity than METsRecently found to be a predictor of prognosis after clinical treadmill testingStudies to date have used all-cause mortality
Heart Rate Drop in Recovery
Probably not more predictive than Duke Treadmill Score or METs
Should be calculated along with Scores as part of all treadmill tests
RPP =SBP(MAX) × HR(MAX)
RPP =SBP(MAX) × HR(MAX)
What is a MET?
What is a MET?
Metabolic Equivalent Term
1 MET = "Basal" aerobic oxygen consumption to stay alive = 3.5 ml O2
/Kg/min
Actually differs with thyroid status, post exercise, obesity, disease states
But by convention just divide ml O2/Kg/min by 3.5
Key MET Values (part 1)
1 MET = "Basal" = 3.5 ml O2 /Kg/min
2 METs = 2 mph on level
4 METs = 4 mph on level
< 5METs = Poor prognosis if < 65; limit immediate post MI; cost of basic activities of daily living
Key MET Values (part 2)
10 METs = As good a prognosis with medical therapy as CABS
13 METs = Excellent prognosis, regardless of other exercise responses
16 METs = Aerobic master athlete
20 METs = Aerobic athlete
Calculation of METs on the Treadmill
METs = Speed x [0.1 + (Grade x 1.8)] + 3.5 3.5
Calculated automatically by Device!
Note: Speed in meters/minute conversion = MPH x 26.8 Grade expressed as a fraction
METs-(Report Exercise Capacity in METs)
Optimize Test by Individualizing for Patient
Adjust test to 8-10 minute duration (aerobic capacity--not endurance)
Use prognostic power of METs
Estimated vs Measured METs
All Clinical Applications based on Estimated Estimated Affected by:
Habituation (Serial Testing) Deconditioning and Disease State
Measured Requires a Mouthpiece and Delicate Equipment
Measured More Accurate and Permits measurement of Gas Exchange Anaerobic Threshold and Other Mxments (VE/VCO2)
Diagnosis vs Prognosis
CARDIAC RISKvs
METs
METs
10 to 15% increase in survival per MET
Can be increased by 25% by a training program
Duke Treadmill Score (uneven lines, elderly?)
Single measurement of steady state heart rate
Can use step or bicycle ergometer
Nomogram is for age 25 years
Need to adjust for older and younger (for which standard table available)
“All-comers” prognostic score
SCORE = (1=yes, 0=no)
METs<5 + Age>65 + History of CHF + History of MI or Q wave
a=0, b=1, c=2, d=more than 2
Interpretation
Parameters at Max Parameters at Max exerciseexercise
Poor conditioningPoor conditioning Pulmonary Pulmonary disordersdisorders
Cardiovascular Cardiovascular disordersdisorders
VO2maxVO2max LowLow LowLow LowLowMETSMETS LowLow LowLow LowLowVEmax/MVVVEmax/MVV LowLow HighHigh LowLowO2 saturationO2 saturation NN LowLow NNVD/VTVD/VT NN N or HighN or High NNHRmax/workloadHRmax/workload HighHigh NN HighHighO2 pulseO2 pulse NN NN LowLow
Diagnosis vs Prognosis
SUMMARYMETs
CPX Testing Procedure and INDICATION
CPX Testing
• Steps in testing
• After filling of Consent form
• Patient prepratation– Baseline READING OR RESTING– Resting EKG– Baseline B/P
AHA/ACC Exercise Testing Guidelines: Recommendations for
Exercise Testing
Diagnosis CAD Prognosis with symptoms/CADAfter MIUsing Ventilatory Gas AnalysisSpecial Groups
AHA/ACC Exercise Testing Guidelines: Recommendations for
Exercise Testing
Special Groups: Pre- and Post-Revascularization Women AsymptomaticPre-surgery Valvular Heart DiseaseCardiac Rhythm Disorders
AHA/ACC Exercise Testing Guidelines: Recommendations for
Exercise Testing
Diagnosis
The ACC/AHA Guidelines for the Diagnostic Use of the Standard
Exercise Test
Class I (Definitely appropriate) - Adult males or females (including RBBB or < 1mm resting ST depression) with an intermediate pre-test probability of coronary artery disease based on gender, age and symptoms (specific exceptions are noted under Class II and III below).
Class IIa (Probably appropriate) - Patients with vasospastic angina.
Diagnostic Use, continued:
•Class IIb (Maybe appropriate) – Patients taking Digoxin with less than 1 mm resting ST depression.
Patients with ECG criteria for left ventricular hypertrophy with less than 1 mm ST depression.
Patients with a high pre-test probability of coronary artery disease by age, symptoms and gender.
Patients with a low pre-test probability of CAD by age, symptoms and gender.
Diagnostic Use, continued:
Class III (Not appropriate) - 1. To use the ST segment response in the diagnosis of coronary artery disease in patients who demonstrate the following baseline ECG abnormalities:
pre-excitation (WPW) syndrome;electronically paced ventricular rhythm; more than one millimeter of resting ST depression;LBBB
2. To use the ST segment response in the diagnosis of coronary artery disease in MI patients
Comparison of Tests for Diagnosis of CAD
Grouping # of Studies
Total # Patients
Sens Spec Predictive Accuracy
Standard ET 147 24,047 68% 77% 73% ET Scores 24 11,788 80% Score Strategy 2 >1000 85% 92% 88%
Thallium Scint 59 6,038 85% 85% 85% SPECT 16+14 5,272 88% 72% 80% Adenosine SPECT 10+4 2,137 89% 80% 85% Exercise ECHO 58 5,000 84% 75% 80% Dobutamine ECHO 5 <1000 88% 84% 86% Dobutamine Scint 20 1014 88% 74% 81% Electron Beam Tomography (EBCT)
16 3,683 60% 70% 65%
Variable Circle response
Sum
Maximal Heart Rate Less than 100 bpm = 30
100 to 129 bpm = 24
130 to 159 bpm =18
160 to 189 bpm =12
190 to 220 bpm =6
Exercise ST Depression
1-2mm =15
> 2mm =25
Age >55 yrs =20
40 to 55 yrs = 12
Angina History Definite/Typical = 5
Probable/atypical =3
Non-cardiac pain =1
Hypercholesterolemia?
Yes=5
Diabetes? Yes=5
Exercise test Occurred =3
induced Angina Reason for stopping =5
Total Score:
MalesChoose
only one per
group
<40=low prob
40-60= intermediate probability
>60=high probability
Positive=-5, Negative=5
Total Score
Reason for stopping =15
induced Angina (x3)Estrogen Status
Occurred =9Exercise test
Yes=10Diabetes? (x2)
Yes=10Smoking? (x2)
Non-cardiac pain =2
Probable/atypical =6
Definite/Typical = 10Angina History (x2)
50 to 65 yrs = 15(x5)
>65 yrs =25Age
> 2mm =10Depression (x2)
1-2mm =6Exercise ST
190 to 220 bpm =4
160 to 189 bpm =8
130 to 159 bpm =12
100 to 129 bpm = 16Rate (x4)
Less than 100 bpm = 20
Maximal Heart
SumCircle response
Variable WomenChoose
only one per
group
<37=low prob
37-57= intermediate probability
>57=high probability
AHA/ACC Exercise Testing Guidelines: Recommendations for
Exercise Testing
Prognosis with symptoms/CAD
The ACC/AHA Guidelines for the Prognostic Use of the Standard Exercise Test
Indications for Exercise Testing to Assess Risk and prognosis in patients with symptoms or a prior history of coronary artery disease:
Class I. Should be used:Patients undergoing initial evaluation with suspected or known CAD. Specific exceptions are noted below in Class IIb.
Patients with suspected or known CAD previously evaluated with significant change in clinical status.
Prognostic Use, continued:
Class IIb. Maybe Appropriate for:Patients who demonstrate the following ECG abnormalities:
Pre-excitation (WPW) syndrome;Electronically paced ventricular rhythm;More than one millimeter of resting ST
depression; andLBBB.
Patients with a stable clinical course who undergo periodic monitoring to guide management
Prognostic Use, continued:
Class IIa. Probably Appropriate: None
Class III. Should not be used for prognostication:
Patients with severe co-morbidity likely to limit life and/or consideration for revascularization procedures
CPX Testing significance Prognostic
Problems with max tests in average/less fit subjects
1. May not be accustomed to exercise at severe levels, so may not reach maximum
2. On a bike, need strong quads, so lightly built subjects, possibly most female subjects, will lack strength to reach VO2max
3. Can use treadmill, but significant minority find treadmill disorienting or have balance problems
Submaximal exercise tests
Most follow this pattern:
Subjects does standardised work scheduleHeart rate is measuredWork capacity at age-predicted heart rate max is calculatedOxygen consumption at work rate calculated for HRmax is estimated from average relation between VO2 and work rate for the test could use a short “ramp” test
Drawbacks of submaximal tests:
Assume reliable HR-VO2 relation across subjects (1 point tests) or linearity of HR relation for multi-point tests
Depend on estimating age-related HRmax.(error +/- 10%)
Assume same VO2-work relation in all subjects, i.e. constant efficiency
Are subject to error from fluctuations in HR due to time of day, eating patterns, uncontrolled stressors.
McArdle estimates a typical submax test can only give VO2max estimates to within +/- 16%
Field Tests
• 12 min run– VO2 = 3.126 (meters in 12 min) - 11.3
• 1.5 mile run– VO2 = 3.5 + 483/(time in minutes)
• Rockport Walking Test (1 mile walk)– VO2 = 132.853 - 0.1692 (BW in kg) - 0.3877 (age in y)
+ 6.315 (gender) - 3.2649 (time in min) - 0.1565 (HR)
– 0 for female; 1 for male; HR at end of walk
Non-exercise methods 1.Use Exercise heart rate variability.
Non-exercise methods 1.Use Exercise heart rate variability.
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0 50 100 150 200 250 300 350 400 450
Time, sec
Heart rate variability during exerciseBest by beat variability falls during exercise. This is due to reduction in vagal (parasympathetic) drive to the heart. Part of the way heart rate is increased (NB other factors are increased sympathetic drive and circulating adrenaline)
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Time, sec
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“Ins
tant
aneo
us”
hear
t rat
e, m
in-1
Resting Moderate-hard exercise
Non-exercise methods 2.
Use just age, gender, level of physical activity, perceived functional ablility (latter two from simple questionnaires). Claimed can estimate fitness to within +/- 3.4 ml/min.kg (SEE, standard error of estimate, so 5% confidence limit about 7 ml/min.kg). This appears better than any of the “real” tests, so some doubt that comparisons are being made in a fair way….
.
Monitoring change in fitness
Submax exercise tests are much more reliable on repeat testing in the same individual. So for following the effect of an “exercise for health” individual programme, they are fine. But in this situation may be better to forget VO2max altogether. Simply follow trend in final heart rate for a standard exercise, e.g. short step test or timed walk test.
SummaryFitness levels vary markedly between individuals and are highly predictive of future health.
Need simple methods to monitor fitness in individuals and in populations
Various sub-max tests are suitable for this purpose. However, because of inherent non-linearities in the underlying physiology, will have low accuracy.
For reliable VO2max estimates in a performance context or clinically, need a maximum test.
Key Points of Exercise Testing
Key Points of Exercise Testing
• Manual SBP measurement (not automated) most important for safety
• Adjust to clinical history• No Age predicted Heart Rate Targets• The BORG Scale of Perceived Exertion• METs not Minutes• Fit protocol to patient (RAMP)• Use standard ECG analysis/ 3 minute
recovery/ use scores• Heart rate recovery • Expired Gas Analysis?
What is the most important prognostic measurement from the exercise test?
1. BORG scale estimate2. ST depression3. Exercise time4. Exercise capacity
Question 1
What is the most appropriate indicator of a maximal effort?
1. BORG scale 2. ST depression3. Heart rate4. Exercise capacity
Question 2
Thank you