Practice ECGs Part I Copyright © 2006 by Mosby Inc. All rights reserved.

Objectives Develop a systematic approach for infarct recognition on the ECG. Gain familiarity with 12-Lead ECG interpretation. Objectives Develop a systematic approach for infarct recognition on the ECG. Gain familiarity with 12-Lead ECG interpretation. Copyright © 2006 by Mosby Inc. All rights reserved.

Reviewing a 12-Lead ECG Assess the quality of the tracing. Identify the rate and underlying rhythm. Examine for evidence of infarction. Assess the quality of the tracing. If baseline wander or artifact is present to any significant degree, note it. If the presence of either of these conditions interferes with the assessment of any lead, use a modifier such as “possible” or “apparent” in your interpretation. Identify the rate and underlying rhythm. Determining rate and rhythm is the first priority when interpreting the ECG. Remember, the treatment of life-threatening dysrhythmias initially takes precedence over the acquisition and interpretation of the 12-Lead ECG. Examine for evidence of infarction. Examine each lead for the presence of a Q wave and/or poor R wave progression. If a Q wave is present, express the duration in milliseconds. Examine each lead for the presence of ST-segment displacement (elevation or depression). If ST-segment elevation is present, express it in millimeters. Assess the areas of ischemia or injury by assessing lead groupings. Examine the T waves for any changes in orientation, shape, and size. If acute myocardial infarction is suspected, mentally picture the cardiac anatomy to localize the infarction and predict which coronary artery is occluded. The relative extent of the infarction can be gauged by the number of leads showing ST-segment elevation. In right coronary artery occlusions, right-sided chest leads should be obtained to help gauge the extent of the infarct and identify possible right ventricular infarction. Copyright © 2006 by Mosby Inc. All rights reserved.

Reviewing a 12-Lead ECG Ascertain if infarct impostors are present that may account for ECG changes. Clinical presentation. Interpret your findings. Ascertain if infarct imposters are present that may account for ECG changes. When changes indicative of an acute infarction are noted on the ECG, ascertain if other conditions are present that might also account for the changes. To accomplish this task, a working list of these conditions is needed. In cases where these conditions are present, do not rule out infarct, but recognize that these ECG changes may be due either to infarction or one of the infarct impostors. Remember, infarction can still occur in the presence of each of these conditions. Therefore, when you are screening potential infarct patients, recognition of indicative changes in the presence of one of the infarct impostors warrants an immediate physician overread. One of the most distracting and frequent imitators is left bundle branch block (LBBB). The ECG changes of LBBB look much like those of infarction. Left ventricular hypertrophy (LVH) occurs more often than does LBBB, but usually provides a less striking resemblance of infarction. Ventricular rhythms, whether occurring spontaneously or as the result of a ventricular pacemaker, are not uncommon and often produce both Q waves and ST-segment elevation. Two less common conditions are pericarditis and early repolarization. The ECG changes produced by pericarditis are very subtle and recognition can be quite difficult. It is often the patient’s clinical presentation that causes the clinician to suspect pericarditis. Once suspected, the specific ECG evidence becomes more apparent. Early repolarization produces no clinical symptoms; it does produce an ECG resembling that of infarction, particularly anterior or anterolateral infarction. Early repolarization accounts for many of the tracings that indicate infarction obtained from young, healthy patients. Clinical presentation Discovering the patient’s clinical presentation is a priority. The inclusion of the clinical presentation at this point does not imply that it is the first time that you should obtain patient information. Rather, it is assumed that you will already have obtained the relevant subjective and objective information from the patient. The specific inclusion of the clinical presentation is included here to emphasize the importance of integrating the clinical presentation into the ECG interpretation. When incorporating the clinical picture into the ECG interpretation, remember that not all patients experiencing an acute coronary syndrome will present with substernal chest pain. A high index of suspicion is always warranted, especially when treating women, diabetics, or the elderly. Complicating the effort to recognize infarction is the fact that only a minority of nontraumatic chest pain is due to infarction. Causes of non-infarction chest pain include pericarditis, aneurysm, musculoskeletal pain, a variety of pulmonary conditions, gastrointestinal disorders, and various emotional and psychologic states. Clearly, the task of early infarct recognition can be challenging. It is the physician’s task to ultimately differentiate infarction from other conditions. Interpret your findings. Copyright © 2006 by Mosby Inc. All rights reserved.

Infarct Impostors Left bundle branch block Ventricular rhythms Left ventricular hypertrophy Pericarditis Early repolarization Copyright © 2006 by Mosby Inc. All rights reserved.

Figure 9-1 Copyright © 2006 by Mosby Inc. All rights reserved.

Poor R wave progression Figure 9-1 Poor R wave progression Copyright © 2006 by Mosby Inc. All rights reserved.

Figure 9-1 Baseline wander or artifact? Baseline wander V1 Interpretation: Extensive anterior infarction, reciprocal changes Low voltage over entire tracing Underlying rhythm? Sinus rhythm at 83 bpm Pathologic Q waves? Leads: III?, V2, V3 Poor R wave progression? Leads: V5 ST-segment elevation? Leads: I, aVL, V1 – V6 ST-segment depression? Leads: II, III, aVF T wave changes? Leads: Inversion III, aVF; tall V3 – V5 Copyright © 2006 by Mosby Inc. All rights reserved.

Practice 9-2 32-year-old Caucasian woman Copyright © 2006 by Mosby Inc. All rights reserved.

Practice 9-2 32-year-old Caucasian woman Artifact Copyright © 2006 by Mosby Inc. All rights reserved.

Practice 9-2 Baseline wander or artifact? Artifact in aVR Interpretation: Normal ECG PR interval 160 ms QRS 80 ms QT/QTc 414/462 ms P-R-T axes 62 42 31 Underlying rhythm? Sinus rhythm at 75 bpm Copyright © 2006 by Mosby Inc. All rights reserved.

Figure 9-3 Copyright © 2006 by Mosby Inc. All rights reserved.

Figure 9-3 Baseline wander Baseline wander Baseline wander Copyright © 2006 by Mosby Inc. All rights reserved.

Figure 9-3 Baseline wander or artifact? Baseline wander in II, III, aVL Interpretation: Anteroseptal infarction, previous inferior wall infarction; low voltage in lead II Underlying rhythm? Sinus rhythm at 93 bpm Pathologic Q waves? Leads: III, aVF ST-segment elevation? Leads: V2, V3; slight in V1 Copyright © 2006 by Mosby Inc. All rights reserved.

Figure 9-4 Copyright © 2006 by Mosby Inc. All rights reserved.

Figure 9-4 Underlying rhythm? Sinus bradycardia at 55 bpm with occasional PVCs Interpretation: Sinus bradycardia with occasional PVCs, otherwise normal ECG PR interval 142 ms QRS 94 ms QT/QTc 436/417 ms P-R-T axes 60 14 54 Copyright © 2006 by Mosby Inc. All rights reserved.

Figure 9-5 Copyright © 2006 by Mosby Inc. All rights reserved.

Poor R wave progression Figure 9-5 Baseline wander Baseline wander Baseline wander Poor R wave progression Baseline wander Copyright © 2006 by Mosby Inc. All rights reserved.

Figure 9-5 Baseline wander or artifact? Baseline wander in I, II, V1, V6 Interpretation: Anteroseptal infarction with lateral extension; reciprocal changes noted Underlying rhythm? Atrial fib at 100 bpm Pathologic Q waves? Leads: aVL Poor R wave progression? Leads: V2 ST-segment elevation? Leads: I, aVL, V1 – V5 ST-segment depression? Leads: II, III, aVF T wave changes? Leads: Peaked T wave V2, tall/peaked V3, V4 Copyright © 2006 by Mosby Inc. All rights reserved.

Figure 9-6 67-year-old Caucasian woman Copyright © 2006 by Mosby Inc. All rights reserved.

Figure 9-6 67-year-old Caucasian woman Copyright © 2006 by Mosby Inc. All rights reserved.

Figure 9-6 Underlying rhythm? Sinus rhythm at 75 bpm Interpretation: Left bundle branch block PR interval 130 ms QRS 144 ms QT/QTc 406/453 ms P-R-T axes 13 -16 58 ST-segment elevation? Leads: V1 – V3 ST-segment depression? Leads: V4 – V6 Copyright © 2006 by Mosby Inc. All rights reserved.

Figure 9-7 71-year-old Caucasian woman Copyright © 2006 by Mosby Inc. All rights reserved.

Figure 9-7 71-year-old Caucasian woman Copyright © 2006 by Mosby Inc. All rights reserved.

Figure 9-7 Underlying rhythm? Sinus bradycardia at 56 bpm Interpretation: Inferior infarction – age undetermined, ST & T wave abnormality – consider lateral ischemia PR interval 168 ms QRS 88 ms QT/QTc 424/402 ms P-R-T axes 7 0 101 ST-segment elevation? Leads: II, III, aVF ST-segment depression? Leads: I, aVL T wave changes? Leads: I, aVL Copyright © 2006 by Mosby Inc. All rights reserved.

Figure 9-8 42-year-old Caucasian woman Copyright © 2006 by Mosby Inc. All rights reserved.

Figure 9-8 Underlying rhythm? Sinus arrhythmia at 67 bpm Interpretation: Normal ECG PR interval 164 ms QRS 66 ms QT/QTc 392/414 ms P-R-T axes 81 84 61 ST-segment depression? Leads: III T wave changes? Leads: Inversion in V1 Copyright © 2006 by Mosby Inc. All rights reserved.

Figure 9-9 Copyright © 2006 by Mosby Inc. All rights reserved.

Figure 9-9 Copyright © 2006 by Mosby Inc. All rights reserved.

Figure 9-9 Baseline wander or artifact? Artifact I, II, III, aVL, V1 Interpretation: Anteroseptal infarction, possible previous lateral infarction. Nearing voltage criteria for LVH. Pattern similar to early repolarization. Underlying rhythm? Sinus rhythm at 77 bpm Pathologic Q waves? Leads: V5, V6; Q wave approaching 40 ms in V4 ST-segment elevation? Leads: V1, V2, V3 ST-segment depression? Leads: V5, V6 T wave changes? Leads: Tall in V2-V4; peaked in II, aVF, V2-V6; inverted in aVL Copyright © 2006 by Mosby Inc. All rights reserved.

Figure 9-10 58-year-old Caucasian man Copyright © 2006 by Mosby Inc. All rights reserved.

Figure 9-10 58-year-old Caucasian man Copyright © 2006 by Mosby Inc. All rights reserved.

Figure 9-10 Underlying rhythm? Sinus bradycardia at 58 bpm Interpretation: Extensive anterior infarction PR interval 184 ms QRS 92 ms QT/QTc 416/409 ms P-R-T axes 39 16 16 ST-segment elevation? Leads: I, aVL, V2 – V6 ST-segment depression? Leads: II, III, aVF Copyright © 2006 by Mosby Inc. All rights reserved.

Figure 9-11 42-year-old Caucasian man Copyright © 2006 by Mosby Inc. All rights reserved.

Figure 9-11 Underlying rhythm? Sinus bradycardia at 56 bpm Interpretation: Sinus bradycardia, otherwise normal ECG PR interval 126 ms QRS 100 ms QT/QTc 432/416 ms P-R-T axes 51 24 29 Copyright © 2006 by Mosby Inc. All rights reserved.

Figure 9-12 Copyright © 2006 by Mosby Inc. All rights reserved.

Figure 9-12 Copyright © 2006 by Mosby Inc. All rights reserved.

Figure 9-12 Underlying rhythm? Sinus tachycardia at 107 bpm Interpretation: Anteroseptal infarction, reciprocal changes present ST-segment elevation? Leads: I, aVL, V1–V5 ST-segment depression? Leads: II, III, aVF T wave changes? Leads: Tall/peaked V2 – V4; inverted in III Copyright © 2006 by Mosby Inc. All rights reserved.

Figure 9-13 Copyright © 2006 by Mosby Inc. All rights reserved.

Figure 9-13 Copyright © 2006 by Mosby Inc. All rights reserved.

Figure 9-13 Underlying rhythm? Sinus rhythm at 71 bpm Interpretation: Inferior infarction; low QRS voltage (<0.5 mV) in limb leads PR interval 144 ms QRS 108 ms QT/QTc 376/398 ms P-R-T axes 43 44 38 ST-segment elevation? Leads: II, III, aVF ST-segment depression? Leads: V1 – V4 Copyright © 2006 by Mosby Inc. All rights reserved.

Figure 9-14 Copyright © 2006 by Mosby Inc. All rights reserved.

Figure 9-14 Copyright © 2006 by Mosby Inc. All rights reserved.

Figure 9-14 Underlying rhythm? Junctional rhythm at 55 bpm Interpretation: Inferior infarction; marked ST depression consistent with subendocardial injury PR interval 0 ms QRS 104 ms QT/QTc 448/436 ms P-R-T axes 999 58 84 ST-segment elevation? Leads: II, III, aVF ST-segment depression? Leads: I, aVL, V1 – V4 T wave changes? Leads: Inverted in aVL, V1 Copyright © 2006 by Mosby Inc. All rights reserved.

Figure 9-15 71-year-old Caucasian woman Copyright © 2006 by Mosby Inc. All rights reserved.

Figure 9-15 71-year-old Caucasian woman Copyright © 2006 by Mosby Inc. All rights reserved.

Figure 9-15 Baseline wander or artifact? Artifact V1, baseline wander V2 Interpretation: Right bundle branch block, inferior infarction – age undetermined PR interval 168 ms QRS 130 ms QT/QTc 388/430 ms P-R-T axes 60 -21 46 Underlying rhythm? Sinus rhythm at 74 bpm Pathologic Q waves? Leads: III, aVF T wave changes? Leads: Inverted V1, V2 Copyright © 2006 by Mosby Inc. All rights reserved.

Figure 9-16 Copyright © 2006 by Mosby Inc. All rights reserved.

Figure 9-16 Copyright © 2006 by Mosby Inc. All rights reserved.

Figure 9-16 Underlying rhythm? Sinus rhythm at 67 bpm Interpretation: Right bundle branch block PR interval 208 ms QRS 122 ms QT/QTc 430/454 ms P-R-T axes 33 80 6 Copyright © 2006 by Mosby Inc. All rights reserved.

Figure 9-17 Copyright © 2006 by Mosby Inc. All rights reserved.

Figure 9-17 Copyright © 2006 by Mosby Inc. All rights reserved.

Figure 9-17 Underlying rhythm? Sinus tachycardia with short PR interval, short QT interval Interpretation: Inferior infarction PR interval 116 ms QRS 76 ms QT/QTc 228/306 ms P-R-T axes 59 2 77 ST-segment elevation? Leads: II, III, aVF ST-segment depression? Leads: I, aVL T wave changes? Leads: Inverted in aVL, V1 Copyright © 2006 by Mosby Inc. All rights reserved.

Figure 9-18 59-year-old Caucasian woman Copyright © 2006 by Mosby Inc. All rights reserved.

Figure 9-18 Underlying rhythm? Sinus bradycardia at 58 bpm Interpretation: Sinus bradycardia, otherwise normal ECG PR interval 122 ms QRS 86 ms QT/QTc 416/408 ms P-R-T axes 41 54 22 Copyright © 2006 by Mosby Inc. All rights reserved.

Figure 9-19 Copyright © 2006 by Mosby Inc. All rights reserved.

Figure 9-19 Copyright © 2006 by Mosby Inc. All rights reserved.

Figure 9-19 Underlying rhythm? Sinus rhythm at 81 bpm Interpretation: Inferior infarction PR interval 184 ms QRS 92 ms QT/QTc 352/389 ms P-R-T axes 60 23 106 Pathologic Q waves? Leads: III ST-segment elevation? Leads: II, III, aVF ST-segment depression? Leads: I, aVL, V5, V6 T wave changes? Leads: Inverted in I, aVL Copyright © 2006 by Mosby Inc. All rights reserved.

Figure 9-20 Copyright © 2006 by Mosby Inc. All rights reserved.

Poor R wave progression Figure 9-20 Poor R wave progression Copyright © 2006 by Mosby Inc. All rights reserved.

Figure 9-20 Baseline wander or artifact? Baseline wander and artifact in lead I, artifact in II, III, aVL Interpretation: Anteroseptal infarction, possible previous inferior infarction Underlying rhythm? Sinus rhythm at 91 bpm Pathologic Q waves? Leads: II?, III, aVF Poor R wave progression? Leads: V3; no initial R wave in V1 ST-segment elevation? Leads: V1 – V4 ST-segment depression? Leads: II T wave changes? Leads: Flattened T wave aVL Copyright © 2006 by Mosby Inc. All rights reserved.

Figure 9-21 Copyright © 2006 by Mosby Inc. All rights reserved.

Figure 9-21 Copyright © 2006 by Mosby Inc. All rights reserved.

Figure 9-21 Baseline wander or artifact? Baseline wander V5, V6 Interpretation: Septal infarction, possible anterior epicardial injury PR interval 164 ms QRS 96 ms QT/QTc 380/433 ms P-R-T axes 62 -62 83 Underlying rhythm? Sinus rhythm at 95 bpm ST-segment elevation? Leads: V1 – V3 ST-segment depression? Leads: II, III, V5, V6 T wave changes? Leads: Inverted in aVL Copyright © 2006 by Mosby Inc. All rights reserved.

Figure 9-22 88-year-old Caucasian man Copyright © 2006 by Mosby Inc. All rights reserved.

Figure 9-22 88-year-old Caucasian man Copyright © 2006 by Mosby Inc. All rights reserved.

Figure 9-22 Underlying rhythm? Sinus rhythm at 65 bpm Interpretation: Inferolateral ischemia Note: This is the same patient as in figure 9-26 – 29 minutes after the ECG in figure 9-26 was obtained PR interval 182 ms QRS 82 ms QT/QTc 410/426 ms P-R-T axes 76 52 -79 ST-segment depression? Leads: II, III, aVF, V4 – V6 T wave changes? Leads: II, III, aVF, V5 – V6 Copyright © 2006 by Mosby Inc. All rights reserved.

Figure 9-23 Copyright © 2006 by Mosby Inc. All rights reserved.

Figure 9-23 Copyright © 2006 by Mosby Inc. All rights reserved.

Figure 9-23 Baseline wander or artifact? Baseline wander lead I Interpretation: Low voltage throughout tracing. Inferior infarction, lateral extension Underlying rhythm? Sinus rhythm at 88 bpm Pathologic Q waves? Leads: V2-V4 ST-segment elevation? Leads: II, III, aVF, V4 – V6 ST-segment depression? Leads: V1 T wave changes? Leads: Peaked in II, III, aVF, V3, V4 Copyright © 2006 by Mosby Inc. All rights reserved.

Practice 9-24 64-year-old Caucasian woman Artifact Copyright © 2006 by Mosby Inc. All rights reserved.

Practice 9-24 Baseline wander or artifact? Artifact in V1 Interpretation: Normal ECG PR interval 154 ms QRS 80 ms QT/QTc 394/449 ms P-R-T axes 77 78 55 Underlying rhythm? Sinus rhythm at 78 bpm Copyright © 2006 by Mosby Inc. All rights reserved.

Figure 9-25 Copyright © 2006 by Mosby Inc. All rights reserved.

Figure 9-25 Artifact Artifact Copyright © 2006 by Mosby Inc. All rights reserved.

Figure 9-25 Underlying rhythm? Sinus rhythm at 69 bpm with occasional PVCs Interpretation: RSR (QR) in V1/V2 consistent with right ventricular conduction delay PR interval 172 ms QRS 104 ms QT/QTc 400/420 ms P-R-T axes 74 69 44 Copyright © 2006 by Mosby Inc. All rights reserved.

Figure 9-26 Copyright © 2006 by Mosby Inc. All rights reserved.

Figure 9-26 Baseline wander Copyright © 2006 by Mosby Inc. All rights reserved.

Figure 9-26 Baseline wander or artifact? Baseline wander V2 Interpretation: Lateral ischemia Underlying rhythm? Sinus rhythm at 67 bpm with occasional PVCs PR interval 190 ms QRS 82 ms QT/QTc 408/431 ms ST-segment depression? Leads: II, aVF, V3-V6 P-R-T axes 76 53 111 T wave changes? Leads: V5, V6 Copyright © 2006 by Mosby Inc. All rights reserved.

Figure 9-27 Copyright © 2006 by Mosby Inc. All rights reserved.

Figure 9-27 Copyright © 2006 by Mosby Inc. All rights reserved.

Figure 9-27 Underlying rhythm? Sinus rhythm at 100 bpm Interpretation: Inferior infarction PR interval 180 ms QRS 96 ms QT/QTc 380/436 ms P-R-T axes 73 35 84 Pathologic Q waves? Leads: III ST-segment elevation? Leads: II, III, aVF ST-segment depression? Leads: aVL T wave changes? Leads: aVL Copyright © 2006 by Mosby Inc. All rights reserved.

Figure 9-28 88-year-old Caucasian woman Copyright © 2006 by Mosby Inc. All rights reserved.

Figure 9-28 88-year-old Caucasian woman Copyright © 2006 by Mosby Inc. All rights reserved.

Figure 9-28 Baseline wander or artifact? Baseline wander V5, V6 Interpretation: Septal infarction, possible anterior epicardial injury Underlying rhythm? Sinus rhythm at 95 bpm ST-segment elevation? Leads: V1- V3 PR interval 164 ms QRS 96 ms QT/QTc 380/433 ms ST-segment depression? Leads: II, III, V5, V6 T wave changes? Leads: Inverted in aVL P-R-T axes 62 -62 83 Copyright © 2006 by Mosby Inc. All rights reserved.

Figure 9-29 Copyright © 2006 by Mosby Inc. All rights reserved.

Figure 9-29 Underlying rhythm? Electronic atrial pacemaker at 80 bpm Interpretation: Electronic atrial pacemaker PR interval 626 ms QRS 92 ms QT/QTc 358/412 ms P-R-T axes 0 52 16 Copyright © 2006 by Mosby Inc. All rights reserved.

Figure 9-30 39-year-old Caucasian man Copyright © 2006 by Mosby Inc. All rights reserved.

Figure 9-30 Underlying rhythm? Sinus tachycardia with nonconducted (blocked) premature atrial complexes at 92 bpm Interpretation: Sinus tachycardia with nonconducted (blocked) premature atrial complexes, otherwise normal ECG PR interval 156 ms QRS 88 ms QT/QTc 326/403 ms P-R-T axes 54 26 54 Copyright © 2006 by Mosby Inc. All rights reserved.

Figure 9-31 Copyright © 2006 by Mosby Inc. All rights reserved.

Figure 9-31 Copyright © 2006 by Mosby Inc. All rights reserved.

Figure 9-31 Underlying rhythm? Sinus rhythm at 62 bpm Interpretation: Anterolateral infarction; meets minimal voltage criteria for LVH, may be normal variant PR interval 168 ms QRS 100 ms QT/QTc 388/393 ms P-R-T axes 55 -29 35 ST-segment elevation? Leads: V2 – V5 ST-segment depression? Leads: II, III, aVF T wave changes? Leads: Tall in V2 – V5 Copyright © 2006 by Mosby Inc. All rights reserved.

Figure 9-32 66-year-old Caucasian woman Copyright © 2006 by Mosby Inc. All rights reserved.

Figure 9-32 66-year-old Caucasian woman Copyright © 2006 by Mosby Inc. All rights reserved.

Figure 9-32 Underlying rhythm? Sinus rhythm at 82 bpm Interpretation: ST-segment elevation? Leads: V1 Incomplete right bundle branch block ST-segment depression? Leads: II, III, aVF, V5, V6 PR interval 136 ms QRS 96 ms QT/QTc 388/453 ms P-R-T axes 62 12 27 Copyright © 2006 by Mosby Inc. All rights reserved.

Figure 9-33 Copyright © 2006 by Mosby Inc. All rights reserved.

Figure 9-33 Copyright © 2006 by Mosby Inc. All rights reserved.

Figure 9-33 Baseline wander or artifact? Baseline wander II, III, aVL, aVF Interpretation: Inferior infarction, reciprocal changes present PR interval 260 ms QRS 104 ms QT/QTc 444/458 ms P-R-T axes 90 -75 105 Underlying rhythm? Sinus rhythm with first-degree AV block at 66 bpm with occasional supraventricular premature complexes Pathologic Q waves? Leads: II, III, aVF ST-segment elevation? Leads: II, III, aVF ST-segment depression? Leads: I, aVL, V1 – V6 T wave changes? Leads: Tall in II, III, aVF; depressed in I, aVL, V1 – V3 Copyright © 2006 by Mosby Inc. All rights reserved.

Figure 9-34 86-year-old Caucasian woman Copyright © 2006 by Mosby Inc. All rights reserved.

Figure 9-34 86-year-old Caucasian woman Baseline wander Copyright © 2006 by Mosby Inc. All rights reserved.

Figure 9-34 Baseline wander or artifact? Baseline wander V4 – V6 Interpretation: Atrial fibrillation with rapid ventricular response PR interval None QRS 90 ms QT/QTc 304/405 ms P-R-T axes None 69 17 Underlying rhythm? Atrial fibrillation at 107 bpm ST-segment depression? Leads: V6 T wave changes? Leads: Tall in V2 Copyright © 2006 by Mosby Inc. All rights reserved.

Figure 9-35 69-year-old Caucasian woman Copyright © 2006 by Mosby Inc. All rights reserved.

Figure 9-35 69-year-old Caucasian woman Copyright © 2006 by Mosby Inc. All rights reserved.

Figure 9-35 Underlying rhythm? Sinus rhythm at 73 bpm Interpretation: Left bundle branch block ST-segment elevation? Leads: V1 – V2 ST-segment depression? Leads: I, II, aVL, aVF, V5 – V6 PR interval 136 ms QRS 144 ms QT/QTc 438/482 ms P-R-T axes 28 -5 238 Copyright © 2006 by Mosby Inc. All rights reserved.