Exercise ECG
-
Upload
laeeq-r-malik -
Category
Documents
-
view
50 -
download
2
description
Transcript of Exercise ECG
EXERCISE STRESS ELECTROCARDIOGRAPHY
Dr.Tahsin N
EXERCISE PHYSIOLOGY
Sympathetic activation
Parasympathetic withdrawal
Vasoconstriction, except-
Exercising muscles
Cerebral circulation
Coronary circulation
↑nor epinephrine and renin
EXERCISE PHYSIOLOGY
↑ventri contractility
↑O2 extraction(upto 3)
↓peripheral resistance
↑SBP,MBP,PP
DBP –no significant change
Pulm vasc bed can accommodate 6 fold CO
CO - ↑ 4-6 times
EXERCISE PHYSIOLOGY
Isotonic exercise(cardiac output)
Early phase- SV+HR
Late phase-HR
Oxygenconsumption(liters/min)
V02 peak
Work rate (watts)
↑ ↑ Exercise work Exercise work ↑ O↑ O22 usage usage
Person’s max. OPerson’s max. O22 consumption (V consumption (V
O2maxO2max) reached) reached
The slope of the o2–work relationship is a measure of
the biochemical efficiency of exercise
V o2max is the product of maximal arteriovenous
oxygen difference and cardiac output
The V o2max depends on
Age
Men than in women
Genetic factors
Cardiovascular impairment
Physical inactivity.
Oxygenconsumption(liters/min)
70% V02 max (trained) V02
peak
(trained)
V02 peak
(untrained)
100% V02 max
(untrained)
Work rate (watts)
The ability to deliver OThe ability to deliver O22 to muscles to muscles and muscle’s and muscle’s
oxidativeoxidative capacity limit a person’s Vcapacity limit a person’s VO2maxO2max.. T Training raining
↑ V↑ VO2maxO2max
175
• During dynamic exercise of
increasing intensity, ventilation
increases linearly over the mild
to moderate range, then more
rapidly in intense exercise
• Workload at which rapid
ventilation occurs is called the
ventilatory breakpointventilatory breakpoint (together
with lactate threshold)
Respiration during exerciseRespiration during exercise
Lactate acidifies the blood, driving off CO2 and increasing ventilatory rate
BLOOD BLOOD PPRESSURE RESSURE (BP) (BP) ALSO RISES IN EXERCISEALSO RISES IN EXERCISE • Systolic pressure (SBP)
goes up to 150-170 mm
Hg during dynamic dynamic
exerciseexercise;; diastolic scarcely
alters
• In isometricisometric (heavy static)
exercise, SBP may exceed
250 mmHg, and diastolic
(DBP) can itself reach 180
Bloodlacticacid(mM)
Relative work rate (% V02 max)
Intense exerIntense exercisecise Glycolysis>aerobic metabolism Glycolysis>aerobic metabolism
↑ ↑ bblood lactate (other organs use some)lood lactate (other organs use some)
Lactate Lactate threshold; threshold; endurance endurance estimationestimation
MAXIMUM HR
HR=220 - age in years
POST EXERCISE PHASE
Vagal reactivation
Imp cardiac deceleration mech
↑in well trained athletes
Blunted in CCF
MET
• Metabolic Equivalent Term
• 1 MET = "Basal" aerobic oxygen consumption to stay alive = 3.5
ml O2 /Kg/min
• Differs with thyroid status, post exercise, obesity, disease
states
KEY MET VALUES
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;
10 METs = same progn with medical thpy as CABG
13 METs = Excell prognosis,
regardless of othr exercise responses
KEY MET VALUES
3-5 METs:
Raking leaves,light carpentry,golf,3-4 mph
5-7 METs:
Exterior carpentry, singles tennis
>9 METs:
Heavy labour, hand ball, squash, running 6-7 mph
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
TREADMILL PROTOCOL
Bruce protocol
Naughton protocol
Weber protocol
ACIP(asymptomatic cardiac ischemia pilot)
Modified ACIP
PROTOCOL DESCRIPTION (BRUCE)
Stage Time (min) M/hr Slope
1 0 1.7 10%
2 3 2.5 12%
3 6 3.4 14%
4 9 4.2 16%
5 12 5.0 18%
6 15 5.5 20%
PROCEDURE
Standard 12 lead ECG- leads distally
Torso ECG + BP
Supine and Sitting / standing
HR ,BP ,ECG
Before, after, stage end
Onset of ischemic response
Each minute recovery(5-10 mints)
PROCEDURE- LEAD SYSTEMS
Mason-Liker modification
RAD
↑inf lead voltage
Loss of Q in inf leads
New Q in AVL
CONTRAINDICATIONS TO EXERCISE TESTING
Absolute
1) Acute MI (< 2 d)
2) High-risk unstable angina
3) Uncontrolled cardiac arrhythmias causing symptoms
or hemodynamic compromise
4) Symptomatic severe AS
5) Uncontrolled symptomatic CCF
6) Acute pulmonary embolus or pulmonary infarction
7) Acute myocarditis or pericarditis
8) Acute Aortic dissection
CONTRAINDICATIONS TO EXERCISE TESTING
Relative
1. LMCA stenosis
2. Moderate stenotic valvular heart disease
3. Electrolyte abnormalities
4. Severe HTN
5. Tachyarrhythmias or bradyarrhythmias
6. HOCM and other forms of outflow tract obstruction
7. Mental or physical impairment leading to inability to
exercise adequately
8. High-degree AV block
Both MI and deaths have been reported and can be expected to occur at a rate of up to 1 per 2500 tests
CLASSIFICATION OF CHEST PAIN
Typical angina
Atypical angina
Noncardiac chest pain
1. Substernal chest discomfort with characterstic quality and duration
2. Provoked by exertion or emotional stress
3. Relieved by rest or NTG
Meets 2 of the above characteristics
Meets one or none of the typical characteristics
‘The post test probability is proportional to the pretest probability’
BAYES' THEOREM A THEORY OF PROBABILITY
PRETEST PROBABILITY
Based on the patient's history ( age, gender, chest pain ),
physical examination and initial testing, and the clinician's
experience.
Typical or definite angina →pretest probability high - test result
does not dramatically change the probability.
Diagnostic testing is most valuable in intermediate pretest
probability category
PRE TEST PROBABILITY OF CORONARY DISEASE BY SYMPTOMS, GENDER AND AGE
Age
Gender
Typical/Definite Angina Pectoris
Atypical/Probable Angina Pectoris
Non-
Anginal Chest Pain
Asymptomatic
30-39
Males
Intermediate
Intermediate
low (<10%)
Very low (<5%)
30-39
Females
Intermediate
Very Low (<5%)
Very low
Very low
40-49
Males
High (>90%)
Intermediate
Intermediate
low
40-49
Females
Intermediate
Low
Very low
Very low
50-59
Males
High (>90%)
Intermediate
Intermediate
Low
50-59
Females
Intermediate
Intermediate
Low
Very low
60-69
Males
High
Intermediate
Intermediate
Low
60-69
Females
High
Intermediate
Intermediate
Low
High = >90% Intermediate = 10-90% Low = <10% Very Low = <5%
INDICATIONS OF EXERCISE TESTING
TO DIAGNOSE OBSTRUCTIVE CAD
Class I
Adult patients (including RBBB or <1 mm of resting ST↓)
with intermediate pretest probability of CAD
Class IIa
Patients with vasospastic angina.
TO DIAGNOSE OBSTRUCTIVE CAD
Class IIb
1. Patients with a high pretest probability of CAD
2. Patients with a low pretest probability of CAD
3. Patients with <1 mm of baseline ST ↓and on digoxin.
4. Patients with LVH and <1 mm baseline ST ↓.
TO DIAGNOSE OBSTRUCTIVE CAD
Class III
1. Patients with the following baseline ECG
abnormalities:
• Pre-excitation syndrome
• Electronically paced ventricular rhythm
• >1 mm of resting ST depression
• Complete LBBB
IN ASYMPTOMATIC PERSONSWITHOUT KNOWN CAD
Class IIa
• Evaluation of asymptomatic T2 DM pts who plan to start
vigorous exercise ( C)
Class IIb
• 1. Evaluation of pts with multiple risk factors as a guide to
risk-reduction therapy.
• 2. Evaluation of asymptomatic men > 45 yrs and women >55
yrs:
• • Plan to start vigorous exercise
• • Involved in occupations which impact public safety
• • High risk for CAD(e.g., PVOD and CRF)
Class III
• Routine screening of asymptomatic
RISK ASSESSMENT AND PROGNOSIS IN PATIENTS WITH SYMPTOMS OR A PRIOR HISTORY OF CAD
Class I
• 1. Initial evaluation with susp/known CAD, includingRBBB or <1
mm of resting ST Depression
• 2.Susp/ known CAD, previously evaluated, now significant
change in clinical status.
• 3. Low-risk UA pts >8 to 12 hrs & free of active ischemia/CCF
• 4. Intermed-risk UApts > 2 to 3 days & no active ischemia/ CCF
Class IIa
• Intermed-risk UA pts – initial markers (N),rpt ECG –no signi
change, and markers >6-12 hrs (N) & no other evidence of
ischemia during observation.
AFTER MYOCARDIAL INFARCTION
Class I
• 1. Before discharge (submaximal --4 to 6 days).
• 2. Early after discharge if the predischarge exercise test was not
done (symptom limited --14 to 21 days).
• 3. Late after discharge if the early exercise test was submaximal
(symptom limited --3 to 6 weeks).
Class IIa
• After discharge as part of cardiac rehabilitation in patients who
have undergone coronary revascularization.
AFTER MYOCARDIAL INFARCTION
Class IIb
1. Patients with the following ECG abnormalities:
• • Complete LBBB
• • Pre-excitation syndrome
• • LVH
• • Digoxin therapy
• • >1 mm of resting ST-segment depression
• • Electronically paced ventricular rhythm
2. Periodic monitoring in patients who continue to participate in
exercise training or cardiac rehabilitation.
AFTER MYOCARDIAL INFARCTION
Class III
1. Severe comorbidity likely to limit life expectancy and/or
candidacy for revascularization.
2. At any time to evaluate pts with AMI with uncompensated
CCF, arrhythmia, or noncardiac exercise limiting conditions.
3. Before discharge to evaluate pts who have already been
selected for, or have undergone, cardiac cath.
Although a stress test may be useful before or after cath
to evaluate or identify ischemia in the distribution of a
coronary lesion of borderline severity, stress imaging tests
are recommended.
Submaximal protocols
• Predetermined end point
• Peak HR 120 bpm, or
• 70% predicted max HR or
• Peak MET - 5
Symptom-limited tests
• To continue till signs or symptoms necessitating termination
(i.e., angina, fatigue, ≥ 2 mm of ST↓,ventricular
arrhythmias, or ≥10-mm Hg drop in SBP from the resting
blood pressure)
BEFORE AND AFTER REVASCULARIZATION
Class I
• 1. Demonstration of ischemia before revascularization.
• 2. Evaluating recurrent symps suggesting ischemia after
revascularization.
Class IIa
• After discharge for activity counseling and/or exercise training as
part of rehabilitation in pts aft revascularization.
BEFORE AND AFTER REVASCULARIZATION
Class IIb
• 1. Detection of restenosis in selected, high-risk
asymptomatic pts < first 12 months aft PCI.
• 2. Periodic monitoring of selected, high-risk asymptomatic
ps for restenosis, graft occlusion, incomplete coronary
revascularization, or disease progression.
Class III
• 1. Localization of ischemia for determining the site of
intervention.
• 2. Routine, periodic monitoring of asymptomatic pts after
PCI or CABG without specific indications.
STRESS TESTING
Modality Sensitivity Specificity
Exercise test 68% 77%
Nuclear Imaging
87-92% 80-85%
Stress
Echo80-85% 88-95%
INVESTIGATION OF HEART RHYTHM DISORDERS
Class I
• 1. Identification of appropriate settings in pts with rate-
adaptive pacemakers.
• 2. Evaluation of cong CHB in pts considering
↑activity/competitive sports. (C)
Class IIa
• 1. Evaluating known or suspected exercise-induced
arrhythmias.
• 2. Evaluation of medical, surgical, or ablative therapy in
exercise-induced arrhythmias
INVESTIGATION OF HEART RHYTHM DISORDERS
Class IIb
1. Isolated VPC in middle-aged pts without other evidence of
CAD.
2. Prolonged 1˚AV block or type I-2˚AV block , LBBB, RBBB,
or VPC in young pts considering competitive sports. (C)
Class III
Routine investigation of isolated VPC in young pts.
INTERPRETING TMT
NORMAL ECG CHANGES DURING EXERCISE
↓ PR, QRS, QT
↑ P amplitude
Progressive downsloping PR in inf leads
j point depression
1 = Iso-electric2 = J point3 = J + 80 msec
THE EXERCISE ECG
ST 60 -- HR > 130/minST 80 -- HR ≤ 130/min
CRITERIA FOR READING ST-SEGMENT CHANGES ON THE EXERCISE ECG
ST DEPRESSION:
Measurements made on 3 consecutive ECG complexes
ST level is measured relative to the P-Q junction
When J-point is depressed relative to P-Q junction at baseline:
Net difference from the J junction determines the amount of deviation
When the J-point is elevated relative to P-Q junction at baseline and
becomes depressed with exercise:
Magnitude of ST depression is determined from the P-Q junction and
not the resting J point
J point depression of 2 to 3
mm in leads V4 to V6 with
rapid upsloping ST segments
depressed approximately 1
mm 80 msec after the J point.
The ST segment slope in leads
V4 and V5 is 3.0 mV/sec. This
response should not be
considered abnormal.
Upsloping
CRITERIA FOR ABNORMAL AND BORDERLINE ST-SEGMENT DEPRESSION
ABNORMAL:
1.0 mm or greater horizontal or downsloping ST
depression at 80 msec after J point on 3 consecutive ECG
complexes
BORDERLINE:
0.5 to 1.0 mm horizontal or downsloping ST depression at
80 msec after J point on 3 consecutive ECG complexes
2.0 mm or greater upsloping ST depression at 80 msec
after J point on 3 consecutive ECG complexes
Normal
Rapid Upsloping
Minor ST Depression
Slow Upsloping
Horizontal
Downsloping
Elevation (non Q lead)
Elevation (Q wave lead)
• In lead V4 , the
exercise ECG result is
abnormal early in the
test, reaching 0.3 mV
(3 mm) of horizontal
ST segment
depression at the end
of exercise.
• Consistent with a
severe ischemic
response.
•The J point at peak exertion is depressed 2.5 mm, the ST segment slope is 1.5 mV/sec, and the ST segment level at 80 msec after the J point is depressed 1.6 mm. •This “slow upsloping” ST segment at peak exercise indicates an ischemic pattern in patients with a high coronary disease prevalence pretest. •A typical ischemic pattern is seen at 3 minutes of the recovery phase when the ST segment is horizontal and 5 minutes after exertion when the ST segment is downsloping.
•Becomes abnormal at 9:30 minutes (horizontal arrow right) of a 12-minute exercise test and resolves in the immediate recovery phase. •This ECG pattern in which the ST segment becomes abnormal only at high exercise workloads and returns to baseline in the immediate recovery phase may indicate a false-positive result in an asymptomatic individual without atherosclerotic risk factors.
ST ELEVATION(LOCALISING)
Abnormal response
– J ↑ ≥0.10mV(1 mm)
– ST 60 ≥0.10mV(1 mm)
– Three consecutive beats
Q wave lead (Past MI)
• Severe RWMA, ↓EF, ↓Prognosis
Non Q wave lead (Past MI)
• Severe ischemic response
Non Q wave lead (No past MI)-1%
• Transmural reversible myocardial ischemia- ----
vasospasm, ↑coronary narrowing
•This type of ECG pattern is usually
associated with a full-thickness, reversible
myocardial perfusion defect in the
corresponding left ventricular myocardial
segments and high-grade intraluminal
narrowing at coronary angiography.
Rarely, coronary vasospasm produces this
result in the absence of significant
intraluminal atherosclerotic narrowing.
ECG Patterns Indicative of Myocardial Ischaemia
ECG Patterns Not Indicative of Myocardial Ischaemia
ECG CHANGES DURING STRESS TEST
ST HEART RATE SLOPE
Maximal change in ST with heart rate calculated at the end of each
stage
Heart rate adjustment of ST segment depression - improve the
sensitivity
Calculation of the maximal ST/heart rate slope in mV/beats/min -
linear regression
An ST/heart rate slope
>2.4 mV/beats/min - abnormal
>6 mV/beats/min - three-vessel CAD.
THE ST/HEART RATE INDEX
Average change of ST segment depression with heart rate
throughout the course of the exercise test.
>1.6 - abnormal
CONFOUNDERS OF EXERCISE TREADMILL TEST INTERPRETATION
Digoxin
Abnormal ST-segment response to exercise
In 25% to 40% of healthy subjects
Related to age.
Left Ventricular Hypertrophy
Decreased specificity
sensitivity is unaffected.
Resting ST Depression
Decreased specificity
CONFOUNDERS OF EXERCISE TREADMILL TEST INTERPRETATION
Left Bundle-Branch Block
Up to 1 cm of ST depression can occur in healthy normal
subjects
Right Bundle-Branch Block
Does not reduce the sensitivity, specificity, or predictive
value of the stress ECG
Beta Blocker Therapy
Reduced diagnostic or prognostic value because of
inadequate heart rate response
EARLY REPOLARIZATION AND RESTING ST↑
Return to the PQ junction is normal
Hence ST↓ determined from PQ junction
Not from the elevated J point before exercise
DUKE TREADMILL SCORE
Treadmill Score=Exercise time
-5X (amount of ST-seg. deviation in mm) - 4X
exercise angina index
(0-no angina, 1 angina, 2 if angina stops test).
High Risk= -11, mortality >5% annually.
Low Risk= +5, mortality 0.5% annually.
Ann Intern Med 1987;106:793.
ACC/AHA GUIDELINES:
Patients with a high-risk exercise test result (mortality ≥ 4%/yr), should be referred for cardiac catheterization.
Pts. with an intermediate-risk result (mortality of 2% to
3%/yr), should be referred for additional testing, either
cardiac catheterization, or an exercise imaging study.
PSEUDO NORMALIZATION PATTERN
No prior MI
Nondiagnostic finding
Prior MI
Suggests Reversible myocardial ischemia
Needs substantiation by rev myo perfusion defect
R WAVE AMPLITUDE
LVH Voltage criteria
ST seg – less reliable to ∆ CAD even in the absence of
LV strain pattern
Loss of R wave (MI)
↓Sensitivity of ST response in that lead
U INVERSION
Occasionally in precordial leads at HR<120
Relatively nonsensitive
Relatively specific
ABNORMAL BP RESPONSE
• Failure to ↑SBP >120 mmHg
• Sustained ↓(15 secs) >10mmHg
• ↓SBP below resting BP during progressive exercise
Inadequate ↑ of CO
3VD LMCA disease
Cardiomyopathy Arrhythmias
Vasovagal LVOT obstruction
Hypovolemia Prolonged vigorous exercise
MAXIMUM WORK CAPACITY
Important prognostic measurement
Work performed in METs
Not the no: of minutes of exercise
EXERCISE CAPACITY
VO max = (mph x 26.8) x (0.1 + [% grade X 1.8] + 3.5
1 MET (metabolic equivalent) = 3.5 ml 0 /kg/min
Stage 1 = 5 METS
Stage 2 = 6 - 8 METS
Stage 3 = 8 -10 METS
22
22
EXERCISE CAPACITY
“The strongest predictor of the risk of death among both
normal subjects, and those with cardiovascular disease”.
“Each 1-MET increase in exercise capacity conferred a 12%
improvement in survival”.
NEJM 2002;346:793-801.
For each 1-MET increase in exercise capacity, the survival improved by 12 percent N Engl J Med 2002
EXERCISE CAPACITY
In pts. with CAD > 13 METS (Stage IV) prognosis excellent
regardless of whether medical or surgical therapy is selected.*
Documented CAD, ≥ 2 mm ST-segment depression. Stage IV
had a 100% 5-year survival rate.**
In the Coronary Artery Surgery Study (CASS), patients with 3-
vessel disease, and high exercise capacity (≥ 10 METS),
showed no benefit from surgery. (JACC 1986;8:741 748)
*Circ 1984;70:226.
**Circ 1982;65:482.
HEART RATE RESPONSE
Inappropriate ↑ at low work load
Anxiety (<1minute-transient)
Persisting several minutes
AF Physically deconditioned
Hypovolemia Anemia
Marginal LV function
HEART RATE RESPONSE
Chronotropic incompetence
Inability to attain THR OR
Abnormal HR Reserve(<80%)
{%HR Reserve=(HRpeak-HRrest)/(220-age-
HRrest)}
Autonomic dysfunction SN dysfuntion,
Drugs Myocardial ischemia
↑long term mortality (not on β blockers)
CHRONOTROPIC INCOMPETENCE
Circ 1996;93:1520..Framingham Heart Study
HEART RATE RECOVERY
During exercise, HR increases due to withdrawal of vagal
tone, and increase of sympathetic tone.
During recovery, there is a rapid reactivation of vagal tone
leading to a decrease in heart rate.
Delayed recovery is a marker of poor outcome
HEART RATE RECOVERY
Abnormal:
1 minute
TMT (upright) < 12 bpm
TMT (supine) < 18 bpm
An upright value <22 bpm at 2 minutes is abnormal
Poor prognosis independent of other factors
EXERCISE INDUCED CHEST DISCOMFORT
Usually after ischemic ST changes
May be associated with increased DBP
In some, only chest discomfort
In CSA, CP less freq than ST↓
Angina with no ST ↓- MPI useful to assess ischemic
severity.
ANGINA DURING STRESS TEST
MortalityMortality
(+) ve Stress Test with angina (+) ve Stress Test with angina 5%/yr.5%/yr.
(+) ve Stress Test, no angina (+) ve Stress Test, no angina 2.5%/yr.2.5%/yr.
Circ 1984;70:547-551.
MARKEDLY POSITIVE STRESS TEST
1. ECG changes in the first three minutes.
2. ECG changes that last through recovery.
3. Hypotensive response.
ADVERSE PROGNOSIS & MULTIVESSEL CAD
1. Symptom limiting exercise < 5METs
2. Abnormal BP response
3. ST↓≥2mm or downsloping ST↓
<5METs, ≥5 leads, persisting ≥5 mins
into reco
4. ST↑
5. Angina at low exercise work loads
6. Reproducible sustained/symptomatic VT
INDICATIONS FOR TERMINATING EXERCISE TESTING
Absolute indications
1. Drop in systolic BP >10 mm Hg from baseline when
accompanied by other evidence of ischemia
2. Moderate to severe angina
3. ↑ CNS sympts (ataxia, dizziness, or near-syncope)
4. Signs of poor perfusion (cyanosis or pallor)
5. Technical difficulties in monitoring ECG or systolic BP
6. Subject’s desire to stop
7. Sustained VT
8. ST ↑ (≥1.0 mm) in leads without Q-waves (other than V1 or
aVR)
INDICATIONS FOR TERMINATING EXERCISE TESTING
Relative indications
1. ↓ in systolic BP (≥10 mm Hg) in the absence of other evidence of
ischemia
2. ST or QRS changes such as excessive ST↓ (>2 mm of horizontal or
downsloping ST↓ ) or marked axis shift
3. Arrhythmias other than sustained VT, including multifocal PVCs,
triplets of PVCs, SVT, heart block, or bradyarrhythmias
4. Fatigue, shortness of breath, wheezing, leg cramps, or claudication
5. Development of BBB or IVCD that cannot be distinguished from VT
6. Increasing chest pain
7. Hypertensive response
THANK YOU