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TMT

TMT. EXERCISE PHYSIOLOGY. Vagal withdrawl-increased HR Symp activation-increased venous return -increased ventilation -increased HR Increase in CO, BP. MET Values . 1 MET = "Basal" = 3.5 ml O2 /Kg/min 2 METs = 2 mph on level

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TMT

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  1. TMT

  2. EXERCISE PHYSIOLOGY • Vagal withdrawl-increased HR • Symp activation-increased venous return • -increased ventilation • -increased HR • Increase in CO, BP

  3. MET Values 1 MET = "Basal" = 3.5 ml O2 /Kg/min 2 METs = 2 mph on level 4 METs = 4 mph on level

  4. 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

  5. Calculationof 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

  6. Exercise is a common physiological stress used to elicit cardiovascular abnormalities not present at rest and to determine adequacy of cardiac function. • TMT is the one of the most frequent noninvasive modalities used to assess patients with suspected or proven cardiovascular disease. • It is used to estimate the prognosis and to determine functional capacity, the likelihood and extent of CAD & effects of therapy.

  7. Tread mill protocol 1.Bruce multistage maximal treadmill protocol has 3min periods to achive steady state before workload is increased. In older individuals or those whose exercise capacity is limited, it can be modified by two 3 min warm up stages at 1.7mph and 0 percent grade and 1.7mph and 5%grade. 2.The Naughton and Weber protocols use 1-2min stages with 1-MET increments between stages, 3.Asymptomatic cardiac ischemia pilot trial and modified ACIP protocols use 2min stages with 1.5mets increments between stages after two 1min warm up

  8. Formula to estimate VO2 from treadmill speed and grade is • Vo2 (ml O2/kg/min)=(mph *2.68) +(1.8*26.82*mph*grade/100)+3.5

  9. Technique 1.Patients should be instructed not to drink,eat caffeinated beverages or smoke 3hr before testing & to wear comfortable shoes and clothes. 2.Unusual physical exertion should be avoided 3.Brief history & physical examination should be performed 4.Should be instructed about risks and benefits 5. Informed consent is taken

  10. 6.12 lead ECG is recorded with electrodes at the distal extremities 8.Torso ECG is obtained in standing and sitting position 9.If false +ve test is suspected,hyperventilation should be performed 11.Area of electrode application should be rubbed with alcohol saturated pad to remove oil and rubbed with sand paper to reduce skin resistance to 5000ohms or less

  11. 12.cables should be light flexible and shielded 13 room temp should be 18 –24 C & humidity less than 60% 13.walking should be demonstrated to the patient 14.HR, BP & ECG should be recorded at the end of each stage. 15.Minimum of 3 leads should be displayed continuously on the monitor 16.A resuscitator cart, defibrillator and appropriate cardioactive drugs should be available in the TMT room. 17. IV line should be started in high risk patients.

  12. Lead system: 1.Arm electrodes should be located in the most lateral aspect of infra clavicular fosse & leg electrode should be above ant iliac crest and below rib cage 2.bipolar lead groups place the negative electrode over manubrium(CM5), right scapula (CB5), RV5 (CC5),or on the forehead (CH5) and active electrode at V5

  13. 1.In myocardial ischemia, ST segment becomes horizontal, with progressive exercise depth of ST segment may increase 2.In immediate post recovery phase ST segment displacement may persist with down sloping ST segments and T wave inversion returning to baseline after 5-10 min 3.In 10% , ischemic response may appear in recovery phase

  14. 1. PQ junction is chosen as isoelectric point , TP segment is true isoelectric point but impractical choice 2. Development of 0.1mv (1mm) or greater of ST segment depression measured from PQ junction with a relatively flat ST segment slope (e.g. <0.7-1mv /sec), 80 msec after J point (ST 80) in 3 consecutive beats with a stable base line is considered to be abnormal response

  15. 3.When ST 80 measurement is difficult to determine at rapid heart rates ST 60 measurements should be used 4.when ST segment is depressed at rest, j point or ST 80 measurements should be depressed an additional 0.1mv or more, to consider abnormal

  16. Upsloping ST segment In patients with high CAD prevalence, slow up sloping ST segment depressed 0.15mv or greater at 80msec, after J point is considered abnormal ST segment elevation Development of 0.1mv ( 1mm) or greater of J point elevation, at 60msec after J point in 3 consecutive beats with stable baseline is considered abnormal response. Occurs in 30% of AWMI & 15% of IWMI When it occurs in non q wave lead in a patient without previous MI it indicates transmural ischemia caused by coronary spasm or high grade coronary narrowing. ST elevation is relatively specific for territory of ischemia

  17. Blood pressure: 1.Normal exercise response is to increase systolic BP progressively with increasing workloads. In normal persons diastolic BP doesn’t change significantly 2.Failure to increase systolic BP beyond 120mm Hg, or a sustained decrease greater than 10 mmHg is abnormal

  18. Heart rate response • Sinus rate increases progressively with exercise. • Inappropriate increase in heart rate at low exercise work loads may occur in patients who are in AF,physically deconditioned, hypovolumic, anemic, or have marginal left ventricular function

  19. Chronotropic incompetence is determined by decreased heart rate sensitivity to the normal increase in sympathetic tone during exercise and is defined as inability to increase heart rate to at least 85%of age predicted maximum. Heart rate reserve is calculated as Chronotropic index refers to heart rate increment per stage of exercise that is below normal. It indicates autonomic dysfunction, sinus node disease, drug therapy(beta blockers), myocardial ischemic response. When chronotropic index is less than 80%, long term mortality is increased

  20. Tread mill (TM) score: is designed to provide survival estimates based on results from exercise test. Provides accurate prognostic & diagnostic information TM score: Exercise time-(5*ST deviation)-(4*treadmill angina index) Angina index- 0-if no angina 1-if typical angina occurs during exercise 2-if angina was the reason pt stopped exercise <5-low risk:no coronary art stenosis or svd-5yr survival of 97% -10 to+4 :-moderate risk --- 5yr survival of 91% >11– high risk: 3vd or Lt main CAD:- 5yr survival of 72%

  21. Rate-pressure product Heart rate –systolic BP product increases progressively with exercise and peak rate pressure product can be used to characterize cardiovascular performance. Normal individuals develop peak rate-pressure product of 20-35 mmHg *beats/min* 10-3 Chest discomfort Chest discomfort usually occurs after the onset of ST segment abnormality

  22. 1.Sensitivity in patients with CAD is 68% and specificity is 77% 2.In SVD -- sensitivity is 25-71% 3.In multivessel CAD-- sensitivity is 81%, specificity is 66% 4.Left main or 3vd -- sensitivity is 86%, specificity is 53%

  23. Asymptomatic population Prevalence of abnormal TMT in asymptomatic middle aged men ranges from 5-12%. Appropriate asymptomatic subjects would be those with an estimated annual risk greater than 1 or 2% per year. Symptomatic patients Exercise should be routinely performed in patients with chronic ischemic heart disease before CAG. Patients who have excellent effort tolerance (>10 METS) have excellent prognosis regardless of anatomical extent of CAD.

  24. Salient myocardial ischemia In patients with documented CAD, exercised induced ST segment depression confers increased risk of subsequent cardiac events Acute coronary syndrome Incidence of angina or ST segment abnormalities in these patients ranges from 30-40%. ST segment changes or chest pain is associated with significantly increased risk of subsequent cardiac events

  25. After MI Exercise testing is useful to determine 1.risk stratification and assessment of prognosis 2.functional capacity for activity prescription 3.assessment of adequacy of medical therapy & need to use supplemental diagnostic or treatment options Ability to complete 5-6METS of exercise or , 70-80% age predicted maximum in the absence of abnormal ECG or BP is associated with 1 year mortality rate of 1-2%.

  26. Preoperative risk stratification before non-cardiac surgery It provides measurement of functional capacity and potential to identify the likelihood of perioperative ischemia in patients with low ischemic threshold

  27. Cardiac arrythmias & conduction disturbances VPCs are common during exercise test & increase with age. Occur in 0-5% of asymptomatic subjects. Suppression of VPCs during exercise is nonspecific. 20% of patients with known heart disease and 50-70% of sudden cardiac death survivors have repetitive ventricular beats induced by exercise. In patients with recent MI, presence of repetitive forms is associated with increased risk of cardiac events. 5 yr all cause mortality is higher in patients who have frequent ectopics in recovery phase.

  28. Test is useful in evaluating : 1.effects of antiarrhythmic drugs 2.detecting supraventricular arrhythmias 3.treating patients with chronic AF to test for ventricular rate control 4.possible drug toxicity in patients on antiarrhythmic drugs Evaluation of ventricular arrythmia 1.Exercise testing provokes VPCs in most patients with sustained ventricular tachyarrythmia. 2.VPC that occurs in the early post exercise phase is associated with worse long term prognosis.

  29. Supraventricular arrythmias Premature beats are seen in 4-10%of normal persons, 40%of patients with underlying heart disease. Sustained arrythmia occur in 1-2%. May approach 10-15% in patients referred for management of episodic arrythmias.

  30. Atrial fibrillation • Rapid ventricular response is seen in initial stages of exercise. • Sinus node dysfunction • Lower heart rate response is seen at submaximal and maximal workloads. • Atrioventricular block • In congenital AV block, exercise induced heart rate is low . Some develop symptomatic rapid junctional rhythms. • In acquired diseases, exercise can elicit advanced AV block.

  31. LBBB ST depression is seen in patients with LBBB & cant be used as diagnostic indicator. Relative risk of death or other major cardiac events in these patients is increased three fold. RBBB Exercise induced ST depression in leads V1-V4 is common in patients with RBBB and is non-diagnostic

  32. In patients with RBBB • 1.new onset ST depression in V5 & V6, or L II or avF • 2.reduced exercise capacity • 3.inability to adequately increase systolic BP • -------indicate presence of CAD. • New development of exercise induced RBBB is uncommon • (0.1%) • Preexcitation syndrome • Presence of WPW syndrome invalidates the use of ST • segment analysis as a diagnostic method. • False +ve ischemic changes are seen • Exercise may normalise QRS complex with disappearance of • delta waves in 20-50%

  33. Exercise induced disappearance of delta wave is more frequent with left sided than right sided pathway Cardiac pacemakers and ICD Test is useful in 1.Evaluating sensor trigger rate adaptive pacing 2.To assess performance following CRT in patients with heart failure and ventricular conduction delay

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