Exercise stress EKG운동 심전도 , 운동부하 심전도

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.

Treadmill protocol

• Bruce protocol• Naughton protocol• Weber protocol• ACIP(asymptomatic cardiac ischemia pilot)• Modified ACIP

The Bruce protocol• 1949 by Robert A. Bruce,

considered the “father of ex-ercise physiology”.

• Published as a standardized protocol in 1963.

• gold-standard for detection of myocardial ischemia when risk stratification is necessary.

BRUCE Protocol

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%

Peak Vo2 is the same regardless of the protocol useddiff – rate at which it is achieved

PROTOCOL USES COMMENTS

BRUCE Normally used large↑Vo2 bet stages\running≥st 3

NAUGHTON&WEBER Limited ex tolerance-CCF 1-2 min stages\1 MET increment

ACIP Established CAD 2 min stages\> linear ↑ in HR & Vo2

MOD-ACIP Short elderly individuals

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)

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

Contraindications to Exercise Testing

Absolute• A/c MI (< 2 d)• High-risk unstable angina• Uncontrolled cardiac arrhythmias causing symp-

toms or hemo compromise• Symptomatic severe AS• Uncontrolled symptomatic CCF• Acute pulmonary embolus or pulmonary infarc-

tion• A/c myocarditis or pericarditis• A/c Ao dissection

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 inabil-

ity to exercise adequately• High-degree AV block

SAFETY & RISKS

In nonselected pat pop-mortality- .01% -morbidity-.05%In k/c CAD- 1 C.arrest/59000 person hours -AMI in 1.4 / 10000 testsArrythmias-AF-Mc-9/10,000 tests -VT-6/10,000 tests -VF- .6/10,000 tests

Deaths& MI estimated occur in 1 of 25000 tests

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

• Sensitivity- a person with the disease having a pos-itive test.

• Specificity-person without the disease having a negative test.

• Prevalence- % in the population having disease.

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 in-termediate-30-70%

Classification of chest pain

• Typical angina1. Substernal chest discomfort with characterstic quality and

duration2. Provoked by exertion or emotional stress3. Relieved by rest or NTG

• Atypical angina• Meets 2 of the above characteristics

• Noncardiac chest pain• Meets one or none of the typical characteristics

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

Age Gender Typical/DefiniteAngina Pectoris

Atypical/ProbableAngina 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%

INTERMEDIATE CATEGORYAGE GROUP GENDER & SYMPTOMS

30-39 YEARS M& F + TYPICAL ANGINA M + ATYPICAL/ PROBABLE ANGINA

40-49 YEARS F + TYPICAL ANGINAM + ATYPICAL/ NON ANGINAL CP

50-59 YEARS F+ TYPICAL ANGINAM&F + ATYPICAL NAGINAM+ NON ACP

60-69 YEARS M& F+ ATYPICAL/PROB ANGINAM&F + NACP

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.

E T TO DIAGNOSE OBSTRUCTIVE CAD

Class IIb1. 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 III1. Patients with the following baseline ECG abnormalities:

• Pre-excitation syndrome• Electronically paced ventricular rhythm• >1 mm of resting ST depression• Complete LBBB

EST SENSITIVITY SPECIFICITY

OVERALL 68% 77%

SVD(LAD>RAD>LCX) 25-71%

MULTIVESSEL DIS 81% 66%

LMCA/3-VD 86% 53%

Exercise Testing in Asymptomatic PersonsWithout 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

RISK ASSESS AND PROG IN PAT WITH SYMP OR A PRIOR HIS-TORY 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 is-chemia/ CCF

Class IIa

Intermed-risk UA pts – initial markers (N),rpt ECG –no signi change, and markers >6-12 hrs (N) & no other evi-dence of ischemia during observation.