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Lesson Four

Lesson Four. COMMON NONINVASIVE DIAGNOSTIC TESTS. CHAPTER 24. The ECG Paper. Horizontally One small box - 0.04 s One large box - 0.20 s Vertically One large box - 0.5 mV. The ECG Paper (cont). 3 sec. 3 sec. Every 3 seconds (15 large boxes) is marked by a vertical line.

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Lesson Four

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  1. Lesson Four

  2. COMMON NONINVASIVE DIAGNOSTIC TESTS CHAPTER 24

  3. The ECG Paper • Horizontally • One small box - 0.04 s • One large box - 0.20 s • Vertically • One large box - 0.5 mV

  4. The ECG Paper (cont) 3 sec 3 sec • Every 3 seconds (15 large boxes) is marked by a vertical line. • This helps when calculating the heart rate.

  5. The 12-Leads The 12-leads include: • 3 Limb leads (I, II, III) • 3 Augmented leads (aVR, aVL, aVF) • 6 Precordial leads (V1- V6)

  6. Views of the Heart Lateral portion of the heart Some leads get a good view of the: Anterior portion of the heart Inferior portion of the heart

  7. ST Elevation One way to diagnose an acute MI is to look for elevation of the ST segment.

  8. Anterior View of the Heart The anterior portion of the heart is best viewed using leads V1- V4.

  9. RateRhythm Axis Intervals Hypertrophy Infarct Right atrial enlargement • Take a look at this ECG. What do you notice about the P waves? The P waves are tall, especially in leads II, III and avF. Ouch! They would hurt to sit on!!

  10. SUMMARYRateRhythm AxisIntervals Hypertrophy Infarct Infarct: Are there T wave changes? No

  11. Rhythm Summary • Rate 90-95 bpm • Regularity regular • P waves normal • PR interval 0.12 s • QRS duration 0.08 s Interpretation? Normal Sinus Rhythm

  12. Rhythm #1 • Rate? 30 bpm • Regularity? regular • P waves? normal • PR interval? 0.12 s • QRS duration? 0.10 s Interpretation? Sinus Bradycardia

  13. Rhythm #2 • Rate? 130 bpm • Regularity? regular • P waves? normal • PR interval? 0.16 s • QRS duration? 0.08 s Interpretation? Sinus Tachycardia

  14. Rhythm #3 • Rate? 70 bpm • Regularity? occasionally irreg. • P waves? 2/7 different contour • PR interval? 0.14 s (except 2/7) • QRS duration? 0.08 s Interpretation? NSR with Premature Atrial Contractions

  15. PVCs • Deviation from NSR • Ectopic beats originate in the ventricles resulting in wide and bizarre QRS complexes. • When there are more than 1 premature beats and look alike, they are called “uniform”. When they look different, they are called “multiform”.

  16. 1st Degree AV Block • Deviation from NSR • PR Interval > 0.20 s

  17. 2nd Degree AV Block, Type I • Deviation from NSR • PR interval progressively lengthens, then the impulse is completely blocked (P wave not followed by QRS).

  18. 3rd Degree AV Block • Deviation from NSR • The P waves are completely blocked in the AV junction; QRS complexes originate independently from below the junction.

  19. ELECTROCARDIOGRAPHY • The ECG / EKG. • The tracing given by the evaluation of electrical impulses generated by the heart during depolarization (contraction) and repolarization (relaxation).

  20. ELECTROCARDIOGRAPHY USED IN THE EVALUATION OF • CHEST PAIN - ISCHEMIA VS. INFARCTION. • RHYTHM DISTURBANCES / ARRHYTHMIAS. • DRUG TOXICITY – digitalis, quinidine. • METABOLIC EFFECTS – electrolytes, hyper and hypokalemia, calcium, magnesium. • CONDUCTION DEFECTS – heart block(s).

  21. HOLTER MONITOR • An ambulatory electrocardiograph. • Used to detect / evaluate arrhythmias that are episodic. • Also used to assess response to treatment.

  22. ELECTROENCEPHALOGRAPHY • The EEG. • Records electrical activity of the brain, mainly the superficial layers of the cortex. • Used to detect foci of abnormal activity, such as in epilepsy. • ALSO: brain death, sleep studies (the “somnogram”), sleep apnea, narcolepsy, etc

  23. ELECTROMYELOGRAPHY • THE EMG – measures electrical activity of muscle. • Used to evaluate neuromuscular disorders, to differentiate between neuropathy (primary disease of motor neurons, such as polio), and myopathy (primary disease of muscle, such as myesthenia gravis).

  24. Normal recruitment pattern • . (A) With minimal effort: a single motor unit is seen firing at 6 Hz. The time between 2 discharges is approximately 166 milliseconds (ms), • (B) Gradual increase in muscle strength results in recruitment of a second motor unit. In this example, it is 12 Hz, the reciprocal of the recruitment interval, which is 85 ms. • (C) With further increase in muscle strength, a third motor unit is recruited.

  25. Amyotphic Lateral Sclerosis: rapid firing unit • myositis, many motor units are activated simultaneously at a low level of muscle contraction. Note the low amplitude and short duration of individual units.

  26. 45-year-old man presented with a 6-month history of progressive muscle weakness. Atrophy of several leg muscles and intrinsic hand muscles accompanied by occasional fasciculations but no sensory loss. The recording is from the anterior tibial muscle. • The motor unit firing at about 25 Hz indicates decreased recruitment as in a neurogenic disorder. The most likely cause in this setting of widespread motor involvement without sensory findings is a motor neuron disorder or motor neuropathy.

  27. PULMONARY FUNCTION TESTS • The PFT’s. • Assessment of inspiration and expiration to determine if a respiratory problem is due to an obstructive defect, a restrictive defect, or both. • OBSTRUCTIVE- an increase in airway resistance; Ex: asthma, COPD. • RESTRICTIVE- a limitation of chest expansion; Ex: pulmonary fibrosis, muscular dystrophy, obesity, severe scoliosis.

  28. PULMONARY FUNCTION TESTS • See text re the various parameters, the FVC, the FEV-1, etc.

  29. The Alveolar Sac

  30. PEAK FLOW TESTING • A hand-held gizmo used in ambulatory monitoring of air flow in patients w/ asthma. • Monitors expiratory capacity, and can be plotted on a daily basis to assess for decreased flow. • Is a sensitive monitor of increased resistance, and can show a change before a patient becomes symptomatic. • Can thus be used for intervention prior to a full-blown flare-up.

  31. http://www.mayoclinic.com/health/asthma/MM00399

  32. Peak Expiratory Flow (liters per minute)

  33. Peak Expiratory Flow RateNORMAL CHILDREN AND ADOLESCENTS

  34. UREA BREATH TEST FOR H.pylori • H. pylori the cause of many cases of gastritis and peptic ulcer. • If detected, can be eradicated and disease healed. • H. pylori produces an urease, an enzyme that breaks down urea, creating CO2 that is absorbed from the GI tract then exhaled. • Test measures changes in CO2 from baseline to after patient is given synthetic urea. • Serologic (antibody) tests exist, but can not differentiate between current and prior infection.

  35. CHAPTER 26 • STRESS TESTS. • CARDIAC CATH. • ELECTROPHYSIOLOGIC STUDIES. • SYNCOPE TESTS.

  36. STRESS TESTS • See http://www.emedicine.com/med/topic2961.htm • For an excellent, comprehensive review of exercise stress testing.,

  37. STRESS TESTS • A test in which a patient exercises on a treadmill, thereby increasing cardiac demand for oxygen while oxygen consumption in skeletal muscle increases. • EKG monitoring is done, looking for evidence of ischemia, ie ST segment depression.

  38. STRESS TESTS USED FOR • 1) Assessment of probability of and extent of coronary artery disease (CAD). • 2) Estimate prognosis in patients w/ CAD. • 3) Determine functional capacity. • 4) Assess the effects of therapy. • 5) Assess need for cardiac cath and / or coronary revascularization.

  39. STRESS TESTS • Mortality – your text says 1 death per 10,000 procedures; eMedicine web site says 1 per 2500. Either way, not a 100% benign study. • Sometimes used in conjuction w/ thallium radionuclide study, whereby post-exercise scans are used to assess myocardial perfusion. The “Thallium Stress Test” or “Thallium Treadmill.”

  40. CARDIAC CATHETERIZATION • Catheterization of the left side of the heart via the femoral artery, or the right side of the heart via the IVC. Dye is injected to assess anatomy of the heart and patency of the coronary arteries. • If aortic stenosis is present the left heart can be assessed from the right heart via the “trans-septal” technique in which a needle injects the dye thru the interventricular septum. • Measurements are taken of pressure to assess flow, and O2 to assess oxygenation.

  41. CARDIAC CATHETERIZATION • USES • Assess cardiac malformations – congenital and acquired such as valvular defects. • Assess need for coronary revascularization, which can be done at the same time via balloon angioplasty, or later via CABG.

  42. OCCLUSION OF THE L.A.D.

  43. ELECTROPHYSIOLOGIC STUDIES • A type of cardiac cath in which electrodes are used to assess cardiac conduction. • Can locate the focus of aberrant conduction pathways. • Can be used for diagnostic as well as therapeutic purposes, such as treatment of tachyarrhythmias.

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