SPDX: STRESS TEST

• Angina was first described in 1772 by the English physician William Heberden.
• The “cornerstone” of modern stress testing was the recognition of the importance of ST segment changes to predict the presence of coronary artery disease
• The ST segment is the flat, isoelectric section of the ECG between the end of the S wave (the J point) and the beginning of the T wave.
• The ST Segment represents the interval between ventricular depolarization and repolarization.
• ST depression occurs when the J point is displaced below baseline.
• 1918 ST depression first noted during angina
• 1928 ST changes during exercise (sit ups) are associated with chest pain & decreased cardiac blood flow
• 1929 Master’s Step test, first “standard” exercise protocol
• 1932 ST depression is present in only 75% of patients with angina during exercise (similar to percentages todAY)
• 1938 First to use maximal exercise testing to test for CAD
• 1940- Continuous EKG monitoring, depression > 1.0 mm is clinically significant
• 1941- EKG changes after exercise can be useful to detect CAD
• 1942- The Harvard Step Test used to assess fitness from HR during recovery
• 1950- Maximal exercise (stair climbing) was more sensitive (88%) to detect CAD than submaximal exercise (39%)
• 1952- Treadmill testing used with set criteria to screen for CAD
• 1954- Cycle tests used to predict fitness
• 1956- Bruce established the guidelines used today: treadmill, with EKG, during exercise
• 1969- Refined interpretation of ST changes (V5 or CM5 most sensitive leads)
• Dr. Robert A. Bruce is the father of the treadmill exercise stress test, died on February 12, 2004 when he was 87 years of age.
• Dr. Bruce used improvements in both EKG's and treadmills to perfect his new procedure.
• His first studies, published in 1949, analyzed minute-to-minute changes in respiratory and circulatory function of normal adults who took a single-stage treadmill test. He then published a paper describing a multistage test in 1963.
• Bayes Theorem was named after 18th-century British mathematician Thomas Bayes, is a mathematical formula for determining conditional probability
• Conditional probability is the likelihood of an outcome occurring in the Bayes Theorem, based on a previous outcome having occurred in similar circumstances
• The probability of a “true” positive stress test depends on the pre-test risk of the patient
• Stress test is used in Medicine to measure heart’s ability to respond to external stress in a controlled clinical environment
• Exercise Stress Test is the most common and basic heart stress test.
• Exercise Stress Test shows how your heart works during physical activity
• Exercise Stress Test usually involves walking on a treadmill or riding a stationary bike.
• A pharmacological stress test is done when an exercise stress test is not possible due to physical limitations like back trouble, joint disease, prior stroke, dizziness or shortness of breath.
• A chemical or pharmacological stress test uses a medication that increases your heart load in the place of exercise.
• A nuclear stress test, also called a myocardial perfusion scan, is a type of nuclear medicine procedure.
• A radiotracer (Tc-99 sestamibi or thallium) is injected in Nuclear Stress Test.
• Scans are acquired with a gamma camera to capture in Nuclear Stress Test.
• Nuclear Stress Test is usally done on two separate days.
• The subject should be instructed not to eat or smoke at least 2 hours prior to the test.
• In general, 6 to 12 minutes of continuous progressive exercise during which the myocardial oxygen demand is elevated to the patient's maximal level is optimal for diagnostic and prognostic purposes.
• The Bruce multistage maximal treadmill protocol has 3-minute periods to allow achievement of a steady state before work-load is increased for next stage
• The Bruce protocol treadmill test was designed by cardiologist Robert A. Bruce in 1963 as a non-invasive test to assess patients with suspected heart disease.
• In this capacity, is perhaps more widely known as a stress test or exercise tolerance test.
• Limitations of Treadmill Stress Test: Sensitivity- 68%