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EXERCISE STRESS TEST Physiology and Protocol, Indications and Contraindications DN.

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Presentation on theme: "EXERCISE STRESS TEST Physiology and Protocol, Indications and Contraindications DN."— Presentation transcript:

1 EXERCISE STRESS TEST Physiology and Protocol, Indications and Contraindications DN

2 Essential ET Terminology Performance of the E S T Assess Exercise Test Responses Interpretation Of The Exercise Stress Test

3 Exercise Test Terminology Vo2max METs Myocardial Oxygen Consumption

4 Maximal Oxygen Uptake (VO2max) Greatest amount of oxygen an individual utilizes with maximal exercise (ml O2 /kg/ min) Gold Standard for cardiorespiratory fitness Fick Equation Vo2max = (HRmax x SVmax) x (CaO2max - CvO2max)

5 VO 2 max = (HRmax X SVmax) X (CaO2max - CvO2max) Genetic Factors (Heart Size) Conditioning Factors Contractility/Afterload/Preload Disease Factors Wall Motion/Ventricular Fn, Valve Stenosis or Regur Skeletal Muscles Aerobic Enzymes Fiber Type Muscle Disease Cap density PaO2 Hgb [ ] SaO2 Diffusion Ventilation Perfusion FICK EQUATION (220 - Age) Sinus Node Dysfunction Drugs (e.g., B - blockers)

6 MET Metabolic Equivalent Term 1 MET = "Basal" aerobic oxygen consumption to stay alive = 3.5 ml O2 /Kg/min inf- thyroid status, post exercise, obesity, disease states

7 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;

8 10 METs = prognosis with med therapy = CABG 13 METs = Excellent prognosis 16 METs = Aerobic master athlete

9 Calculation of METs on the Treadmill METs = Speed x [0.1 + (Grade x 1.8)] Calcul automatically by device Speed in meters/minute = MPH x 26.8 Grade expressed as a fraction

10 Myocardial (MO 2 ) Accurate measurement - cardiac catheterization n Coronary Flow x Coronary (a – v)O2 diff n HR, SBP, LVEDV, CONTRACTILITY, WALL THICKNESS.

11 Myocardial Oxygen Consumption Indirectly measured as the Double Product Double Product = HR x SBP – A normal value is greater than 20,000 – 25,000 – < 20,000 is low heart work load – > 29,000 indicates high heart work load Angina & SToccur at the same DP for an individual

12 Types of Exercise 1. Isometric (Static) -weight-lifting -pressure work for heart, limited cardiac output 2. Isotonic (Dynamic) -walking, running, swimming, cycling -Flow work for heart - CO, TPR 3. Mixed

13 Exercise physiology Sympathetic activation Parasympathetic withdrawal Vasoconstriction, except in- – Exercising muscles – Cerebral circulation – Coronary circulation norepinephrine and renin

14 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 times

15 Exercise physiology Isotonic exercise(cardiac output) Early phase- SV+HR Late phase-HR

16 peak oxygen consumption- age, sex, & training level of the person performing the exercise The plateau in peak oxygen consumption- Vo2 max Vo2 max is limited by 1)the ability to del O 2 to sk. muscles 2) muscle oxidative capacity. Oxygen consumption (liters/min) Work rate (watts) V 0 2 peak (V O2max )

17 dynamic exercise- ventilation increases linearly over the mild to moderate range, then > rapidly in intense exercise ventilatory breakpoint workload at which rapid ventilation occures is called the ventilatory breakpoint (together with lactate threshold) Respiration during exercise Lactate acidifies the blood, driving off CO2 and increasing ventilatory rate

18 BP rise in exercise BP rise in exercise dynamic exercise; (SBP) up to mm Hg during dynamic exercise; diastolic rarely alters isometric isometric - SBP may250 mmHg, and DBP can reach 180

19 Blood lactic acid (mM) Relative work rate (% V 0 2 max) Intense exercise Glycolysis>aerobic metabolism blood lactate Intense exercise Glycolysis>aerobic metabolism blood lactate Lactate threshold; endurance estimation

20 Age Pred Max HR APMHR=220 - age in years\ APMHR=200-1/2 age MHR with age Lower/higher than actual value(+/_12beats) Not used as an indicator of max exertion in EST/ Indi to terminate test

21 .

22 Post exercise phase Vagal reactivation -Imp-cardiac decceleration mech in well trained athletes Blunted in CCF


24 Exercise Stress Testing Pathophysiology: – At rest- adequate coronary blood flow – with exercise-supply\demand mismatch -ST segment changes – 70-80%occlusion - detection by EST – Sign CAD can exist with a -VE Exercise Stress Test.

25 Treadmill protocol EST- stand protocols to progressively cardiovascular work load in a uniform and repro ducible way Bruce protocol Naughton protocol Weber protocol ACIP(asymptomatic cardiac ischemia pilot) Modified ACIP

26 The Bruce protocol 1949 by Robert A. Bruce, considered the father of exercise physiology. Published as a standardized protocol in gold-standard for detection of myocardial ischemia when risk stratification is necessary.

27 BRUCE Protocol StageTime (min)M/hrSlope % % % % % %

28 Peak Vo2 is the same regardless of the protocol used diff – rate at which it is achieved PROTOCOL USES COMMENTS BRUCENormally usedlargeVo2 bet stages\runningst 3 NAUGHTON&WEBERLimited ex tolerance-CCF1-2 min stages\1 MET increment ACIPEstablished CAD2 min stages\> linear in HR & Vo2 MOD-ACIPShort elderly individuals

29 Procedure Standard 12 lead ECG- leads Torso ECG + BP – Supine and Sitting / standing HR,BP,ECG – Before,after,stage – Onset of ischemic response – Each min recovery(5-10 mints)

30 Procedure- Lead systems Mason-Liker modification-extremity electrodes moved to torso 2 motion artifacts – RAD – inf lead voltage – Loss of inf lead q – New Q in AVL

31 Contraindications to Exercise Testing Absolute A/c MI (< 2 d) High-risk unstable angina Uncontrolled cardiac arrhythmias causing symptoms or hemo compromise Symptomatic severe AS Uncontrolled symptomatic CCF Acute pulmonary embolus or pulmonary infarction A/c myocarditis or pericarditis A/c Ao dissection

32 Contraindications to Exercise Testing Relative LMCA stenosis Mod- stenotic VHD Electrolyte abnormalities Sev HTN Tachyarrhythmias or bradyarrhythmias HOCM and other outflow tract obstructions Mental or physical impairment leading to inability to exercise adequately High-degree AV block

33 SAFETY & RISKS In nonselected pat pop-mortality-.01% -morbidity-.05% In k/c CAD- 1 C.arrest/59000 person hours -AMI in 1.4 / tests Arrythmias-AF-Mc-9/10,000 tests -VT-6/10,000 tests -VF-.6/10,000 tests Deaths& MI estimated occur in 1 of tests

34 The post test probability is proportional to the pretest probability To diagnose, test sensitivity,specificity& prevalence in the population being tested req Bayes' theorem A theory of probability

35 Sensitivity- a person with the disease having a positive test. Specificity-person without the disease having a negative test. Prevalence- % in the population having disease.

36 Pretest Probability Based on the pat's h/o ( age, gender, chest pain ), phy ex and initial testing, and the clinician's experience. Typical or definite angina pretest probability high - test result does not dramatically change the probability. Diag power maximal when the pretest probability is intermediate-30-70%

37 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

38 Pre Test Probability of Coronary Disease by Symptoms, Gender and Age


40 E T TO DIAGNOSE OBSTRUCTIVE CAD Class I Adult (including RBBB or <1 mm of resting ST) with intermed pretest probability of CAD Class IIa Patients with vasospastic angina.

41 E T TO DIAGNOSE OBSTRUCTIVE CAD Class IIb 1. Patients - high pretest probability of CAD 2. Patients - 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. 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


43 Exercise Testing in Asymptomatic Persons Without Known CAD Class I None. Class IIa Evaluation of asymP DM pts - plan to start vigorous exercise ( C) Class IIb 1. Eval of pts with multiple risk factors - guide to risk-reduction therapy. 2. Eval 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

44 RISK ASSESS AND PROG IN PAT WITH SYMP OR A PRIOR HISTORY OF CAD Class I 1. Initial evalu with susp/known CAD +/- RBBB or <1 mm of resting ST Depression 2.Susp/ known CAD, previously evaluated-+ signi change in clinical status nw 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.

45 AFTER MYOCARDIAL INFARCTION Class I 1. Before discharge (submaximal --4 to 6 days). 2. Early after discharge (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.

46 AFTER MYOCARDIAL INFARCTION Class IIb 1. Patients with the following ECG abnormalities: Complete LBBB Pre-excit synd LVH Dig therapy >1 mm of resting ST-segment dep paced ventricular rhythm 2. Periodic monitoring in patients who continue to participate in exercise training or cardiac rehabilitation. Class III 1. Severe comorbidity likely to limit life expectancy and/or candidacy for revascularization. 2. any time to eval 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..

47 Submaximal protocols predetermined end point, often a peak HR 120 bpm, or 70% predicted max HR or peak MET – 5 Symptom-limited tests to continue till signs or sympt needing termination (i.e., angina, fatigue, 2 mm of ST,v. arrhy, or 10-mm Hg drop in SBP from the resting blood pressure)

48 The incidence of fatal cardiac events(inclu fatal MI & cardiac rupture) % Nonfatal MI and successfully resuscitated cardiac arrest % Complex arrhythmias, including VT --1.4%. Symptom-limited protocols have an event rate that is 1.9 times that of submaximal tests

49 High risk predischarge Present Absent Cardiac cath strategy 2 strategy3 symp lim EST(14-21d) sub max (4-7d)

50 Symp lim EST(14-21 days) Markedly ab mildly ab negative Card cath Ex imaging Reversible ischemia no rev ischemia Med Rx

51 Sub max (4-7 days) Markedly ab mildly ab negative Ex imaging Rev ischemia no rev isch symp lim ex(3-6wks) card cath markedly ab mildly ab negative rev isch no rev isch Med Rx

52 E S T Before and After Revascularization Class I 1. Demo of ischemia before revascularization. 2. Eval rec symps suggesting ischemia aft revascularization. Class IIa Aft discharge for activity counseling and/or exercise training as part of rehabilitation in pts aft 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.

53 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

54 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.

55 IN VALVULAR HEART DISEASE Class1- c/c AR-Fun capacity & symp resp in pats with equivocal sympt Class 2A c/c AR- FN capacity- athletic activity prog in c/c AR before AVR

56 Stress Testing Modality Sensitivity Specificity Exercise test68%77% Nuclear Imaging 87-92%80-85% Stress Echo 80-85%88-95%


58 Normal Response to Stress Testing Heart rate increases Blood pressure increases Cardiac output increases Total peripheral resistance decreases Dysrhythmias – isolated unifocal PVCs and PACs (suppressed at increased heart rate) Oxygen consumption increases

59 Abnormal Response to Stress Testing Heart rate fails to rise above 120 or unable to attain THR of 85% of max SBP shows a drop Physically unable to complete test Marked hypertension, >260/115 Chest Pain and/or unusual shortness of breath

60 Normal Response of ECG to Stress Testing ECG Changes – QRS complex in size – PR,QRS,QT shorten – J point, resulting in up sloping of ST segment – ST segment returns to baseline by 80 milliseconds – PR segment may down slope(Inf leads– baseline PQ junction) – R amplitude may decr at rates > 130 – P ampl – T wave decreases

61 The Electrocardiographic Response

62 1 = Iso-electric 2 = J point 3 = J + 80 msec The Exercise ECG

63 ST HR > 130/min ST HR 130/min

64 Criteria for Reading ST-Segment Changes on the Exercise ECG ST DEPRESSION: Measurements made on 3 consecutive ECG complexes ST level is meas rel to the P-Q junction When J-point is dep rel to P-Q junction at baseline: – Net diff from the rest J junction - amount of deviation When the J-point is rel to P-Q junction at baseline and becomes isoel with exercise: – Mag of ST dep - P-Q junction and not the resting J point

65 Abnormal and Borderline ST-Segment Depression ABNORMAL: – 1.0 mm or > horizontal or downsloping ST dep at 80 msec after J point on 3 consecutive ECG complexes BORDERLINE: – 0.5 to 1.0 mm horizontal or downsloping ST dep at 80 msec after J point on 3 consecutive ECG complexes – 1.5 mm or > upsloping ST dep at 80 msec after J point on 3 consecutive ECG complexes

66 ECG changes during stress test

67 Normal Rapid Upsloping Minor ST Depression Slow Upsloping

68 Horizontal Downsloping Elevation (non Q lead) Elevation (Q wave lead)

69 ECG Patterns Indicative of Myocardial Ischaemia ECG Patterns Not Indicative of Myocardial Ischaemia

70 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. severe ischemic response.

71 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. slow upsloping ST segment at peak exercise indicates an ischemic pattern in patients with a high coronary disease prevalence pretest. 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.

72 abnormal at 9:30 minutes ES test and resolves in the immediate recovery phase. 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.

73 ST Elevation Abnormal response – J 0.10mV(1 mm) – ST mV(1 mm) – Three consecutive beats Q wave lead (Past MI) Severe RWMA, EF, Prognosis Non Q wave lead (Past MI) Severe ischemic response Localise the culprit Non Q wave lead (No past MI)-1% Transmural reversible myocardial ischemia vasospasm, coronary narrowing

74 ST segment elevation in leads V2 and V3 with lesser degrees of ST segment elevation in leads V1 and V4 and J point depression with upsloping ST segments in lead II, associated with angina 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 coronary vasospasm produces this result in the absence of significant intraluminal atherosclerotic narrowing

75 Confounders of EST Interpretation Digoxin – abnormal ST-segment response to exercise. – occurs in 25% to 40% – directly related to age. LVH – specificity of EST, sensitivity unaffected. – still the first test – Ab test- ref to add tests Resting ST – Resting ST-segment -even otherwise adverse

76 LBBB – Ex-induced ST -no asso with ischemia – no level of ST-seg dep - diag RBBB – do not sensitivity, specificity, or predictive value β- # THERAPY – routine- unnecessary- to stop beta-blockers- symp – in patients taking - diag & prog value - inadequate HRR

77 ERS and resting ST Return to the PQ Jn –nl ST meas from PQ jn Not from the elevated J point before ex.

78 Duke Treadmill Score Treadmill Score = Ex.tme (min) -5 х (ST-seg dev in mm)- 4 х ex.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

79 DUKE TM SCORE Independent prog information =y good in males & females Not as effective in age 75 yrs


81 ACC/AHA Guidelines: high-risk test result- mortality 4%/yr for cardiac cath Intermediate-risk result -mortality 2- 3%/yr additional testing- cardiac cath, exercise imaging study

82 Pseudo normalization pattern of T No prior MI Nondiagnostic finding Prior MI Sugg Reversible myocardial ischemia Needs - rev myo perfusion defect

83 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

84 U inversion Occ in precordial leads at HR<120 Relatively insensitive but Relatively specific 4 CAD

85 ST/HR SLOPE MAESUREMENTS HR adj of ST seg dep- sensitivity ST/HR slope of 2.4 mV/beats/min-abnormal >6mV/beats/min -3 vessel disease CORNELL protocol-gradual inc in HR ST seg/HR index-av change of ST dep with HR through out the course of ex test > 1.6 -abnormal

86 Abnormal BP Response Failure to SBP >120 mmHg Sustained (15 secs) >10mmHg SBP below resting BP during progressive exe Inadequate of CO Hypo episode 3- 9% of symp pats Extensive CAD & perfusion defects LMCA/ 3 VD

87 Exercise Capacity VO max = (mph x 26.8) x (0.1 + [% grade X 1.8] Stage 1 = 5 METS Stage 2 = METS Stage 3 = METS 2 2

88 1-MET in exercise capacity, the survival improved by 12 % N Engl J Med 2002

89 Heart rate response Chronotropic incompetence-adv prog Inability to attain THR OR Ab HRR (<80%) {%HR Reserve=(HR peak -HR rest )/(220-age- HR rest )} Chronotropic index ANS dysfunction,SN dysfuntion, drugs, myocardial ischemia long term mortality-< 80%CI (not on β blockers)

90 Heart Rate Recovery -Rapid reactivation of vagal tone - in heart rate post ex- nl -Slow decceleration post ex - vagal tone HRR=HR (peak)-HR (1 min later)

91 TMT (upright)< 12 bpm TMT (supine)< 18 bpm upright value <22 bpm at 2 minutes is abnormal Prognostic power independent of other factors

92 HRR Predicts Outcome in CAD

93 Exercise induced Chest discomfort Usually after ischemic ST changes +/-DBP chest discomfort –only sgn of CAD In CSA, CP less freq than ST Angina with no ST - MPI to assess ischemic severity. (+) Stress Test with angina 5%/yr.( mortality) (+) Stress Test with angina 5%/yr.( mortality) (+) Stress Test, no angina 2.5%/yr. (+) Stress Test, no angina 2.5%/yr.

94 Adverse prognosis & multivessel CAD Symptom limiting exercise < 5METs Abnormal BP response ST 2mm or downsloping ST <5METs, 5 leads, persisting 5 mins into recovery ST( except aVR) Angina at low exercise work loads Reproducible sustained/symptomatic VT

95 Indications for Terminating Exercise Testing Absolute indications SBP >10 mm Hg fm baseline +other evidence of ischemia Mod - severe angina CNS sympts (ataxia, dizziness, or near-syncope) Signs of poor perfusion (cyanosis or pallor) Technical diff in monitoring ECG or systolic BP Subjects desire to stop Sustained VT ST (1.0 mm) in leads without Q-waves (other than V1 or aVR)

96 Relative indications in S BP (10 mm Hg) in the absence of other evidence of ischemia ST or QRS changes - excessive ST (>2 mm of horizontal or downsloping ST ) or marked axis shift Arrhythmias other than sustained VT, including multifocal PVCs, triplets of PVCs, SVT, heart block, or bradyarrhythmias Fatigue, shortness of breath, wheezing, leg cramps, or claudication Devp of BBB or IVCD that cannot be distinguished from VT Increasing chest pain Hypertensive response(250/115 mm hg)

97 Sub maximal ex test Signs & sympt of ischemia Att of a work load of 6 METS 85% of APMHR HR of 110 beats / min –on β blockers BORG score 17


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