Stress testingStress testing

Physiology:Physiology:

Sympathetic system activation increases: Sympathetic system activation increases: Heart rateHeart rateStroke volumeStroke volumeCardiac outputCardiac outputVentricular contractilityVentricular contractilityAfterload (Vasoconstriction)Afterload (Vasoconstriction)Muscular & Coronary flow (Vasodilatation)Muscular & Coronary flow (Vasodilatation)

Demand vs. Supply Demand vs. Supply

Coronary flowOxygen consumption

(VO2)

Resting VO2 = 1 Mets = 3,5 ml O2 / min / kg.

Exercise testsExercise tests

Master testMaster test

Bicycle Bicycle

TreadmillTreadmill

ECG - 3 leads (V5), 12 ECG - 3 leads (V5), 12 leadsleads

Computerized ST Computerized ST analysisanalysis

Treadmill stress testTreadmill stress test

Positive stress testPositive stress test

Anginal pain or dyspneaAnginal pain or dyspnea

ST↓ horizontal ST↓ horizontal >>1 mm 0.08” after J point1 mm 0.08” after J point

ST↓ downsloping ST↓ downsloping >> 0.5 mm 0.5 mm

ST↓ upsloping ST↓ upsloping >> 1.5 mm 1.5 mm

ST↑ elevationST↑ elevation

QRS wideningQRS widening

Exercise test accuracyExercise test accuracy

SensitivitySensitivity =% of pts. w. CAD & ETT(+) ~ 66 % =% of pts. w. CAD & ETT(+) ~ 66 %

SpecificitySpecificity = % of normals with ETT(-) ~77 % = % of normals with ETT(-) ~77 %

False negative: borderline lesions, collateralsFalse negative: borderline lesions, collaterals

False positive: LVH, MVP, digitalis, LBBBFalse positive: LVH, MVP, digitalis, LBBB

Indications for ETTIndications for ETT

I. I. DiagnosticDiagnostic – probability of CAD – probability of CAD Evaluation of symptoms: chest pain, Evaluation of symptoms: chest pain,

dyspnea, fatiguedyspnea, fatigue Asymptomatic – Multiple CAD risk factorAsymptomatic – Multiple CAD risk factor ScreeningScreening Functional CapacityFunctional Capacity Detection of Arrthymia and response to RxDetection of Arrthymia and response to Rx Hypertensive responseHypertensive response

II. II. PrognosticPrognostic::

Known CAD – risk stratificationKnown CAD – risk stratification

Stable AP, or worsening AP, DOE, FCStable AP, or worsening AP, DOE, FC

Before and after revascularization Before and after revascularization (PTCA, CABG)(PTCA, CABG)

Pre operative risk evaluationPre operative risk evaluation

Indications for ETTIndications for ETT

III. III. Post Acute Coronary SyndromePost Acute Coronary Syndrome

Need for revascularization Need for revascularization Medical treatment adjustment Medical treatment adjustment

(AP, BP, HR, Arrhythmias)(AP, BP, HR, Arrhythmias)Guide for cardiac rehabilitation, Guide for cardiac rehabilitation, Self-confidenceSelf-confidenceTiming of return to work and its intensityTiming of return to work and its intensity

Indications for ETTIndications for ETT

High risk ETT High risk ETT > 4 % Mortality risk> 4 % Mortality risk

Low F.C. < 6 min exerciseLow F.C. < 6 min exercise

ST depression at low HR or stressST depression at low HR or stress

ST depression > 2 mmST depression > 2 mm

ST elevation or QRS wideningST elevation or QRS widening

Severe AP or dyspneaSevere AP or dyspnea

Arrhythmias (VT, PAF)Arrhythmias (VT, PAF)

Systolic BP dropSystolic BP drop

Contraindications for ETTContraindications for ETT

Risk < 0.01 %, Post MI 0.03%Risk < 0.01 %, Post MI 0.03%

Unstable AnginaUnstable AnginaAcute Heart FailureAcute Heart FailureArrhythmiasArrhythmiasMyo- or Peri-carditisMyo- or Peri-carditisSevere Aortic StenosisSevere Aortic StenosisHypertrophic obstructive cardiomyopathyHypertrophic obstructive cardiomyopathySevere Hypertension (>220/110 mmHg)Severe Hypertension (>220/110 mmHg)

Exercise testingExercise testing

Fasting, off Fasting, off ββ-blockers-blockers

Symptom limited: Symptom limited:

AP, dyspnea, dizziness, fatigue, leg painAP, dyspnea, dizziness, fatigue, leg pain

Max. heart rate = 220 – ageMax. heart rate = 220 – age

Target heart rate: 85 % of max. HRTarget heart rate: 85 % of max. HR

If not achieved – non diagnostic testIf not achieved – non diagnostic test

Stop ifStop if: ST↓ : ST↓ >> 3 mm, ST↑, SBP↓ > 10mmHg, 3 mm, ST↑, SBP↓ > 10mmHg,

technical problems with ECG monitoringtechnical problems with ECG monitoring

Nuclear CardiologyNuclear Cardiology

Myocardial perfusionMyocardial perfusion

Thallium – 201Thallium – 201

Cyclotron product: dose - 2 mCurieCyclotron product: dose - 2 mCurie

Long half life – 72 hoursLong half life – 72 hours

85% - first pass myocardial uptake85% - first pass myocardial uptake

Na-K-ATPase pumpNa-K-ATPase pump

Redistribution: 4 or 24 hr.= viabilityRedistribution: 4 or 24 hr.= viability

LAO view of the heart

(pathology)

SRV

PW

A

LV

Thallium image during anginaThallium image during angina

Thallium - planar views of the heartThallium - planar views of the heart

ThalliumThalliumTreadmill Treadmill

stress stress testtest

Severe exercise – induced ischemia

Multiple defects, lung uptake, LV dilatation

Thalium 201Thalium 201

DiagnosisDiagnosis

Infarct: Perfusion defect at stress and restInfarct: Perfusion defect at stress and rest

Ischemia: Defect at stress that normalizes after Ischemia: Defect at stress that normalizes after 4 or 24 hours.4 or 24 hours.

Sensitivity ~ 90 %Sensitivity ~ 90 %

Specificity ~ 80 %Specificity ~ 80 %

Localization of ischemia / infarctLocalization of ischemia / infarct

Extend and severity of CADExtend and severity of CAD

Functional vs. anatomic assessment (angio)Functional vs. anatomic assessment (angio)

Planar vs. spect (tomographic) imagingPlanar vs. spect (tomographic) imaging

Normal Myocardial Perfusion

Myocardial Ischemia

Myocardial Infarction

Technetium SestamibiTechnetium Sestamibi

Higher dose (30 mCurie), improved image Higher dose (30 mCurie), improved image qualityquality

Shorter half life (6 hours)Shorter half life (6 hours)

No redistribution, therefore 2 separate No redistribution, therefore 2 separate injections for rest and stressinjections for rest and stress

ECG gating for wall motion, EFECG gating for wall motion, EF

First pass imagingFirst pass imaging

Pharmacologic vs. stress imagingPharmacologic vs. stress imaging

Indicated for pts. unable to complete full stress Indicated for pts. unable to complete full stress test due to low HR, PVD, COPD, CHF, test due to low HR, PVD, COPD, CHF, orthopedic disabilityorthopedic disability

Adenosin or dypiridamole drip: vasodilatation Adenosin or dypiridamole drip: vasodilatation

of normal vs. narrowed coronariesof normal vs. narrowed coronaries

Thallium or Tech. sestamibi injectionThallium or Tech. sestamibi injection

Perfusion abnormality similar to stressPerfusion abnormality similar to stress

Contrast left Contrast left ventricular ventricular

angiography: angiography: Antero – apical Antero – apical

aneurysmaneurysmRAO viewRAO view

Diastole

Systole

Technetium 99 labeled RBCTechnetium 99 labeled RBC

First pass image or at equilibriumFirst pass image or at equilibriumMultigated acquisition (MUGA)Multigated acquisition (MUGA)Regional wall motion at rest and / or stressRegional wall motion at rest and / or stress

Ejection Fraction (%)= X 100Ejection Fraction (%)= X 100

Assessment of ischemia Assessment of ischemia Viability: Dobutamine effectViability: Dobutamine effect

m

EDC - ESC

EDC

ECG – gated acquisition

MUGA – RAO viewMUGA – RAO view

MUGA – LAO viewMUGA – LAO view

RVLV

Diastole Systole

RV LV

MUGA – bicycle exerciseMUGA – bicycle exercise

Gated Cardiac Results

Indications for nuclear testingIndications for nuclear testing

I.I. DiagnosticDiagnostic

CAD assessment – best for intermediate CAD assessment – best for intermediate likelihood of CADlikelihood of CAD

Extent and severity of CADExtent and severity of CAD Extent of ischemic vs. infarcted areasExtent of ischemic vs. infarcted areas Need for revascularization Need for revascularization

II. II. PrognosticPrognostic: :

Risk stratification - MI / Death:Risk stratification - MI / Death:

0.5 – 50 % for normal vs. high risk scan0.5 – 50 % for normal vs. high risk scan

Pre-operative assessmentPre-operative assessment

Post ACS / MIPost ACS / MI

Change in symptoms / ETT resultsChange in symptoms / ETT results

Indications for nuclear testingIndications for nuclear testing

High risk nuclear testHigh risk nuclear test

Multiple and / or severe perfusion defectsMultiple and / or severe perfusion defects

Increased lung uptakeIncreased lung uptake

Stress induced LV dilatation Stress induced LV dilatation

III. III. Viability studyViability study (hybernating vs. scar tissue) (hybernating vs. scar tissue)

Thallium late redistributionThallium late redistribution

MUGA with dobutamine dripMUGA with dobutamine drip

Positron emission tomography (PET)Positron emission tomography (PET)

Mismatch between reduced perfusion Mismatch between reduced perfusion (ammonia or rubidium) and preserved (ammonia or rubidium) and preserved metabolism (glucose)metabolism (glucose)

Improved function following revascularizationImproved function following revascularization

Indications for nuclear testingIndications for nuclear testing

PET Scan: Viability studyPET Scan: Viability study