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Title | Description | Subject | Collection |
51 |
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Atypical LBBB with Q waves in leads I and aVL | In typical LBBB, there are no initial Q waves in leads I, aVL, and V6. If Q waves are present in 2 or more of these leads, myocardial infarction is present. | | Knowledge Weavers ECG |
52 |
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AV dissociation by default | The nonconducted PAC's set up a long pause which is terminated by ventricular escapes; note the wider QRS morphology of the escape beats indicating their ventricular origin. Incomplete AV dissociation occurs during the escape beats, since the atria are still under the control of the sinus node. | | Knowledge Weavers ECG |
53 |
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AV dissociation by default | If the sinus node slows too much a junctional escape pacemaker may take over as indicated by arrows. AV dissociation is incomplete, since the sinus node speeds up and recaptures the entricles. | | Knowledge Weavers ECG |
54 |
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AV dissociation by usurpation | Normal sinus rhythm is interrupted by an accelerated ventricular rhythm whose rate is slightly faster than the sinus rhythm. Fusion QRS complexes occur whenever the sinus impulse enters the ventricles at the same time the ectopic ventricular focus initiates its depolarization. | | Knowledge Weavers ECG |
55 |
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AV sequential pacemaker - marquette | (Summary) | | Knowledge Weavers ECG |
56 |
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Bifascicular block: RBBB + LAFB | Bifascicular block: RBBB + LAFB | | Knowledge Weavers ECG |
57 |
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Bifascicular block: RBBB + LAFB | This is the most common of the bifascicular blocks. RBBB is most easily recognized in the precordial leads by the rSR' in V1 and the wide S wave in V6 (i.e., terminal QRS forces oriented rightwards and anterior). LAFB is best seen in the frontal plane leads as evidenced by left axis deviation (-50... | | Knowledge Weavers ECG |
58 |
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Bradycardia-dependent LBBB with carotid sinus massage | When carotid sinus massage slows the heart rate in this example, the QRS widens into a LBBB. This form of rate-dependent bundle branch block is thought to be due to latent pacemakers in the bundle undergoing phase 4 depolarization; when the sinus impulse enters the partially depolarized bundle, slow... | | Knowledge Weavers ECG |
59 |
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Calibration signal - marquette | Calibration signal - marquette | | Knowledge Weavers ECG |
60 |
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Cardiac conduction system diagram - marquette | Cardiac conduction system diagram - marquette | | Knowledge Weavers ECG |
61 |
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Compensatory vs. non-compensatory pauses - marquette | Compensatory vs. non-compensatory pauses - marquette | | Knowledge Weavers ECG |
62 |
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Complete AV block (3rd degree) with junctional rhythm | Complete AV block (3rd degree) with junctional rhythm | | Knowledge Weavers ECG |
63 |
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Complete AV block, junctional escape rhythm, and ventriculophasic sinus arrhythmia | Complete AV block is seen as evidenced by the AV dissociation. A junctional escape rhythm sets the ventricular rate at 45 bpm. The PP intervals vary because of ventriculophasic sinus arrhythmia; this is defined when the PP interval that includes a QRS is shorter than a PP interval that excludes a ... | | Knowledge Weavers ECG |
64 |
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Conceptual framework: aArrhythmias and conduction abnormalities | Conceptual framework: aArrhythmias and conduction abnormalities | | Knowledge Weavers ECG |
65 |
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Diagram: frontal plane leads | Diagram: frontal plane leads | | Knowledge Weavers ECG |
66 |
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Diagram: stages of acute Q-wave MI | Diagram: stages of acute Q-wave MI | | Knowledge Weavers ECG |
67 |
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Diagram: type I vs. type II 2nd degree AV block | In type I 2nd degree AV block the PR progressively lengthens until a nonconducted P wave occurs. The PR gets longer by smaller and smaller increments; this results in gradual shortening of the RR intervals. The RR interval of the pause is usually less than the two preceding RR intervals. The RR i... | | Knowledge Weavers ECG |
68 |
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Diagram: AV nodal reentrant tachycardia | The AV node often has dual pathways; in this diagram the alpha pathway is fast, but has a long refractory period; the beta pathway is conducts more slowly, but recovers faster.In sinus rhythm the faster alpha pathway is used and accounts for the normal PR interval. When a PAC occurs, however, the i... | | Knowledge Weavers ECG |
69 |
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Diagram: digitalis effect on rhythm and conduction | Diagram: digitalis effect on rhythm and conduction | | Knowledge Weavers ECG |
70 |
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Diffuse anterolateral T wave abnormalities | Diffuse anterolateral T wave abnormalities | T Wave Abnormalities | Knowledge Weavers ECG |
71 |
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Digitalis intoxication: Junctional tachycardia with and without AV block | In a patient with longstanding atrial fibrillation being treated with digoxin, a regular tachycardia, as seen in A, with a RBBB suggests a junctional or supraventricular tachycardia. Group beating, in B, is likely due to a 2nd degree, Type 1, exit block below the ectopic junctional focus. This is h... | | Knowledge Weavers ECG |
72 |
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Digitalis intoxication: junctional tachycardia with and without exit block | In A the rhythm is junctional tachycardia with RBBB. In B there is 2nd degree exit block with a 3:2 conduction ratio; i.e., every 3rd junctional impulse fails to reach the ventricles... at least for the first two groupings on 1.4sec. | | Knowledge Weavers ECG |
73 |
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ECG components diagram - marquette | ECG components diagram - marquette | | Knowledge Weavers ECG |
74 |
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ECG intervals and waves | The P wave represents atrial activation; the PR interval is the time from onset of atrial activation to onset of ventricular activation. The QRS complex represents ventricular activation; the QRS duration is the duration of ventricular activation. The ST-T wave represents ventricular repolarizatio... | | Knowledge Weavers ECG |
75 |
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ECG of the century - part II: dual AV pathways | An astute cardiology fellow, yours truly, went to the patient's bedside on Day 2 and massaged the right carotid sinus as indicated by the arrow. Four beats later at a slightly slower heart rate the PR interval suddenly normalized suggesting an abrupt change from a slow AV nodal pathway to a fast AV... | | Knowledge Weavers ECG |