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ECG Basics
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Powerpoint slides for ECG basic sciences ECG presentation for teaching medical graduates
Dr (Prof) Subroto MandalFollow
Doctor at Mamata medical College, Khammam, APAdvertisement
ECG Basics
- Basics of ECG http://emergencymedic.blogspot.com Dr Subroto Mandal, MD, DM, DC Associate Professor, Cardiology
- MODERN ECG INSTRUMENT
- With EKGs we can identify Arrhythmias Myocardial ischemia and infarction Pericarditis Chamber hypertrophy Electrolyte disturbances (i.e. hyperkalemia, hypokalemia) Drug toxicity (i.e. digoxin and drugs which prolong the QT interval)
- NORMAL ECG
- EKG Leads which measure the difference in electrical potential between two points 1. Bipolar Leads: Two different points on the body 2. Unipolar Leads: One point on the body and a virtual reference point with zero electrical potential, located in the center of the heart
- EKG Leads The standard EKG has 12 leads: 3 Standard Limb Leads 3 Augmented Limb Leads 6 Precordial Leads
- Standard Limb Leads
- Standard Limb Leads
- Augmented Limb Leads
- All Limb Leads
- Precordial Leads
- Precordial Leads
- Right Sided & Posterior Chest Leads
- Arrangement of Leads on the EKG
- Anatomic Groups (Septum)
- Anatomic Groups (Anterior Wall)
- Anatomic Groups (Lateral Wall)
- Anatomic Groups (Inferior Wall)
- Anatomic Groups (Summary)
- RULE 6 The R wave must grow from V1 to at least V4 The S wave must grow from V1 to at least V3 and disappear in V6
- P Pulmonale P Mitrale
- QRS in LVH & RVH
- Conditions with Tall R in V1
- Right Atrial and Ventricular Hypertrophy
- Variable Shapes Of ST Segment Elevations in AMI Goldberger AL. Goldberger: Clinical Electrocardiography: A Simplified Approach. 7th ed: Mosby Elsevier; 2006.
- T wave
- QT Interval
- Determining the Heart Rate Rule of 300/1500 10 Second Rule
- Rule of 300 Count the number of “big boxes” between two QRS complexes, and divide this into 300. (smaller boxes with 1500) for regular rhythms.
- What is the heart rate? (300 / 6) = 50 bpm
- What is the heart rate? (300 / ~ 4) = ~ 75 bpm
- What is the heart rate? (300 / 1.5) = 200 bpm
- The Rule of 300 It may be easiest to memorize the following table: 50 6 60 5 75 4 100 3 150 2 300 1 Rate No of big boxes
- 10 Second Rule EKGs record 10 seconds of rhythm per page, Count the number of beats present on the EKG Multiply by 6 For irregular rhythms.
- What is the heart rate? 33 x 6 = 198 bpm
- Calculation of Heart Rate
- The QRS Axis The QRS axis represents overall direction of the heart’s electrical activity. Abnormalities hint at: Ventricular enlargement Conduction blocks (i.e. hemiblocks)
- The QRS Axis Normal QRS axis from -30 ° to +90 ° . -30 ° to -90 ° is referred to as a left axis deviation (LAD) +90 ° to +180 ° is referred to as a right axis deviation (RAD)
- Determining the Axis The Quadrant Approach The Equiphasic Approach
- Determining the Axis Predominantly Positive Predominantly Negative Equiphasic
- Quadrant Approach: Example 1 Negative in I, positive in aVF RAD
- Quadrant Approach: Example 2 Positive in I, negative in aVF Predominantly positive in II Normal Axis (non-pathologic LAD)
- The Equiphasic Approach 1. Most equiphasic QRS complex. 2. Identified Lead lies 90° away from the lead 3. QRS in this second lead is positive or Negative
- QRS Axis = -30 degrees
- QRS Axis = +90 degrees-KH
- Equiphasic Approach Equiphasic in aVF Predominantly positive in I QRS axis ≈ 0°
- Thank You
- BRADYARRYTHMIA Dr Subroto Mandal, MD, DM, DC Associate Professor, Cardiology
- Sinus Bradycardia
- Junctional Rhythm
- Mobitz type 1 (Wenckebach Phenomenon)
- Third Degree Heart Block 3rd degree AV block with a left ventricular escape rhythm, 'B' the right ventricular pacemaker rhythm is shown.
- The nonconducted PAC's set up a long pause which is terminated by ventricular escapes; Wider QRS morphology of the escape beats indicating their ventricular origin. AV Dissociation
- AV Dissociation Due to Accelerated ventricular rhythm
- Thank You
- Ventricular Conduction Normal Signal moves rapidly through the ventricles Abnormal Signal moves slowly through the ventricles
- RIGHT ATRIAL ENLARGEMENT
- Left Ventricular Hypertrophy
- Bundle Branch Blocks
- Normal Impulse Conduction Sinoatrial node AV node Bundle of His Bundle Branches Purkinje fibers
- RBBB
- HYPERKALEMIA
- HYPERKALEMIA
- SEVERE HYPERKALEMIA
- HYPOKALEMIA
- HYPOKALEMIA
- HYPOKALEMIA
- HYPERCALCEMIA
- HYPOCALCEMIA
- ACUTE PERICARDITIS
- ACUTE PERICARDITIS
- CARDIAC TAMPONADE
- PERICARDIAL EFFUSION-Electrical alterans
- HYPOTHERMIA-OSBORNE WAVE
- HYPOTHERMIA- Giant Osborne waves
Editor's Notes
- Atrial depolarisation Electrically both atria act almost as one. They have relatively little muscle and generate a single, small P wave. P wave amplitude rarely exceeds two and a half small squares (0.25 mV). The duration of the P wave should not exceed three small squares (0.12 s). The wave of depolarisation is directed inferiorly and towards the left, and thus the P wave tends to be upright in leads I and II and inverted in lead aVR. Sinus P waves are usually most prominently seen in leads II and V1. A negative P wave in lead I may be due to incorrect recording of the electrocardiogram (that is, with transposition of the left and right arm electrodes), dextrocardia, or abnormal atrial rhythms. Normal P waves may have a slight notch, particularly in the precordial (chest) leads. Bifid P waves result from slight asynchrony between right and left atrial depolarisation. A pronounced notch with a peaktopeak interval of > 1 mm (0.04 s) is usually pathological, and is seen in association with a left atrial abnormality—for example, in mitral stenosis.
- The R wave in lead V6 is smaller than the R wave in V5, since the V6 electrode is further from the left ventricle. The depth of the S wave, generally, should not exceed 30 mm in a normal individual (although > 30 mm are occasionally recorded in normal young male adults) In another website it is also shown that small q wave seen in leads III and aVF Normal q-waves reflect normal septal activation (beginning on the LV septum); they are narrow (<0.04s duration) and small (<25% the amplitude of the R wave). They are often seen in leads I and aVL when the QRS axis is to the left of +60o, and in leads II, III, aVF when the QRS axis is to the right of +60o. Septal q waves should not be confused with the pathologic Q waves of myocardial infarction (http://medstat.med.utah.edu/kw/ecg/ecg_outline/Lesson3/index.html)
- Sokolow + Lyon (Am Heart J, 1949;37:161) S V1+ R V5 or V6 > 35 mm Cornell criteria (Circulation, 1987;3: 565-72) SV3 + R avl > 28 mm in men SV3 + R avl > 20 mm in women Framingham criteria (Circulation,1990; 81:815-820) R avl > 11mm, R V4-6 > 25mm S V1-3 > 25 mm S V1 or V2 + R V5 or V6 > 35 mm R I + S III > 25 mm Romhilt + Estes (Am Heart J, 1986:75:752-58) Point score system
- ST segment depression is always an abnormal finding, although often nonspecific (http://medstat.med.utah.edu/kw/ecg/ecg_outline/Lesson3/index.html)
- As a general rule, T wave amplitude corresponds with the amplitude of the preceding R wave, though the tallest T waves are seen in leads V3 and V4. Tall T waves may be seen in acute myocardial ischaemia and are a feature of hyperkalaemia.
- Poor Man's Guide to upper limits of QT: For HR = 70 bpm, QT<0.40 sec; for every 10 bpm increase above 70 subtract 0.02 sec, and for every 10 bpm decrease below 70 add 0.02 sec. For example: QT < 0.38 @ 80 bpm QT < 0.42 @ 60 bpm
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