16
Answers and Teaching Points to Chapter 14 EKGs
Rate: 72 beats per minute (bpm)
Rhythm: Regular, sinus
Axis: Normal +30 degrees
Block: First-degree atrioventricular (AV) block with PRi approximately 280 milliseconds
Infarction: None
Interpretation: Normal sinus rhythm with first-degree AV block
Teaching point: The PR interval is greater than one large box, which is consistent with a first-degree AV block. This is not uncommon in the setting of antiarrhythmic therapy with Flecainide, given its mechanism of action.
Rate: 156 bpm
Rhythm: Regular, sinus
Axis: Normal +30 degrees
Block: None
Infarction: None
Interpretation: Sinus tachycardia
Teaching point: The QRS complexes are narrow and fast, but there are P waves visible in most leads. These findings, in addition to the clinical information of anxiety, are consistent with sinus tachycardia.
Rate: 60 bpm
Rhythm: Regular, sinus
Axis: Normal +60 degrees
Block: None
Infarction: None
Interpretation: Sinus rhythm with mild sinus arrhythmia
Teaching point: There are normal appearing P waves prior to each QRS complex. The rate is approximately 60 bpm. Mild sinus arrhythmia with a normal to slow resting heart rate is common in a young, healthy, physically active patient.
Rate: 78 bpm
Rhythm: Regular, sinus
Axis: Borderline right axis deviation. Lead I is isoelectric placing the axis at approximately +90 degrees
Block: Slight prolongation of the QTc. Note that the QT interval is slightly more than half the R–R interval in most leads.
Infarction: Anteroseptal ST elevation and T wave inversion involving the anterior and lateral leads
Interpretation: Normal sinus rhythm with acute anterolateral injury pattern. This is causing a slight prolongation of the QTc and delayed R wave transition in the precordial leads.
Teaching point: There is ST segment elevation with terminal T wave inversion. This finding is consistent with a hyperacute injury pattern. There is T wave inversion in the lateral leads consistent with an early ischemic pattern. This is an EKG that warrants immediate attention given the extent of the actively ischemic process.
Rate: 72 bpm
Rhythm: Irregularly irregular involving repetitive cycles. This is due to variable block in the setting of atrial flutter. The flutter waves are negative in leads II, III, and aVF and positive in lead V1.
Axis: Normal axis. aVF is predominantly positive, although the QRS is partially obscured by the flutter waves. Lead I is positive.
Block: None, although the flutter waves are blocking in a variable 3:1 to 4:1 pattern.
Infarction: None evident
Interpretation: Typical atrial flutter with a controlled, variable ventricular response
Teaching point: There are sawtooth flutter waves in between the QRS complexes, which follow a typical pattern. The QRS complexes are irregularly irregular. Atrial flutter is a common arrhythmia in the setting of structural heart disease, especially that which involves the mitral valve, given the association with atrial enlargement.
Rate: 36 bpm
Rhythm: Regular, sinus
Axis: Left axis. aVR is most isoelectric placing the axis at approximately –60 degrees
Block: Complete AV block
Infarction: Cannot reliably evaluate for ischemia in the setting of a ventricular escape rhythm.
Interpretation: Complete AV block with a ventricular escape at a rate of 36 bpm
Teaching point: There is clear evidence of AV dissociation with a wide QRS complex consistent with complete heart block and a ventricular escape rhythm. Patients with first-degree AV block and a left bundle branch block should be followed closely to optimize early recognition of the progression of conduction system disease.
Rate: 72 bpm
Rhythm: Regular, sinus
Axis: Left axis. Lead II is the most isoelectric placing the axis at approximately –30 degrees.
Block: None
Infarction: 3 to 4 mm ST segment elevation in the inferior leads with reciprocal ST depression in the lateral leads. There is 1- to 2-mm ST depression in the anteroseptal leads as well.
Interpretation: Normal sinus rhythm with acute inferior wall injury pattern and posterior involvement
Teaching point: There is significant ST segment elevation above the baseline in the inferior leads. Reciprocal ST segment depression is seen in the lateral leads confirming this as an acute inferior wall injury pattern. There is ST segment depression in leads V1 to V2 (positive mirror sign) consistent with posterior wall involvement.
Rate: Approximately 84 bpm
Rhythm: Irregularly irregular consistent with atrial flutter with variable block. P waves are positive in leads II, III, aVF, and V1.
Axis: Right axis. Lead I is predominantly negative and lead aVF is predominantly positive. Lead aVR is isoelectric, placing the axis at approximately +120 degrees.
Block: None, although the atrial flutter is occurring with a variable 3:1 to 4:1 block
Infarction: None
Interpretation: Atypical atrial flutter with variable block and a controlled ventricular response
Teaching point: There are sawtooth flutter waves in between irregular QRS complexes, consistent with atrial flutter with a variable ventricular response. The P waves do not follow a typical pattern. Obstructive sleep apnea and chronic obstructive pulmonary disease are both risk factors for atrial flutter, as their respective underlying pathophysiology ultimately causes myocyte stretching and strain.
Rate: 66 bpm
Rhythm: Regular, sinus
Axis: Normal +30 degrees
Block: The QRS complex is wide and greater than 120 milliseconds. Left bundle branch block pattern is evident upon examination of leads V1 and V6.
Infarction: None evident
Interpretation: Normal sinus rhythm with left bundle branch block and probable left atrial enlargement
Teaching point: The QRS complexes are very wide, negative in lead V1, and positive in lead V6. They are also positive in lead I and aVL. These findings are consistent with a left bundle branch block. Dilated cardiomyopathy can be associated with a left bundle branch block due to extensive myocardial damage.
Rate: 84 bpm
Rhythm: Regular, sinus
Axis: Right axis. Lead I is negative and lead aVF is positive. Lead aVR has both positive and negative forces, placing the axis at approximately +120 degrees
Block: No evidence of heart block. The negative forces in leads I and aVL are the result of Q waves from an old lateral wall MI, not from a true posterior fascicular block, which would cause an rS pattern in these leads
Infarction: Q waves are predominantly seen in the lateral leads with anterior involvement causing poor R wave progression in the precordial leads
Interpretation: Normal sinus rhythm with old anterolateral wall myocardial infarction causing poor R wave progression across the precordial leads
Teaching point: This patient has suffered an extensive myocardial infarction involving the anterior and lateral wall. The axis points to the right (negative QRS in lead I) because electrical vectors are pointing away from the area of infarcted myocardium.
Rate: 150 bpm
Rhythm: Regular with evidence of AV dissociation
Axis: Right axis. Lead I is negative and lead aVF is positive. Lead aVR is most isoelectric placing the axis at approximately +120 degrees.
Block: Right bundle branch block pattern. Evidence of A-V dissociation is noted with visible P waves in several leads.
Infarction: Unable to evaluate given the rapid rate and wide QRS
Interpretation: Rapid monomorphic ventricular tachycardia with a right bundle branch block pattern
Teaching point: The ventricular rate is rapid, the QRS complexes are wide, and there is evidence of AV dissociation. These findings are consistent with ventricular tachycardia. When in doubt, a wide complex tachycardia should be treated as ventricular tachycardia (VT) until proven otherwise. It is important to note that there is not a true right bundle branch block. The EKG appearance of VT will reflect where the rhythm is generated from within the ventricles. This concept is beyond the scope of this text.
Rate: 42 bpm
Rhythm: Regular. P waves noted in 2:1 pattern with QRS
Axis: Left axis. Lead aVR is the most isoelectric placing the axis at approximately –60 degrees
Block: Right bundle branch block, left anterior fascicular block with 2:1 AV block
Infarction: T waves are inverted in several leads, likely the result of the ventricular conduction delay
Interpretation: 2:1 AV block with right bundle branch block and left anterior fascicular block
Teaching point: There are two P waves for every one QRS complex. Every other P wave is associated with a QRS complex. There is evidence of advanced conduction system disease with a right bundle branch block pattern in leads V1 and V6 in the setting of a left axis deviation. This left axis deviation in the setting of a right bundle branch block should raise suspicion for a concomitant left hemiblock, which can be confirmed by an rS pattern in the inferior leads and a qR pattern in the lateral limb leads. The patient is “dropping” every other QRS complex due to this advanced conduction system disease, and is likely experiencing periods of ventricular standstill during her symptoms.
Rate: 84 bpm
Rhythm: Irregularly irregular without identifiable P waves
Axis: Normal +30 degrees
Block: None
Infarction: None
Interpretation: Atrial fibrillation with a variable but controlled ventricular response
Teaching point: There are irregularly irregular QRS complexes with no identifiable P waves in between them. This is consistent with atrial fibrillation. This inefficient rhythm is likely causing her to experience exertional fatigue and shortness of breath.
Rate: 36 bpm
Rhythm: Regular with sinus activity and AV association
Axis: Normal +30 degrees
Block: None
Infarction: None
Interpretation: Sinus bradycardia with slow ventricular response
Teaching point: The ventricular rate is less than 60 bpm and there is a normal appearing P wave associated with each QRS complex. This is consistent with sinus bradycardia, likely secondary to his beta blocker. Given his symptoms, a medication or dosage change is warranted. Follow-up should be scheduled afterward to ensure a resolution of his symptoms.
Rate: 60 bpm
Rhythm: Regular, sinus
Axis: Left axis. Lead aVR is most isoelectric placing the axis at approximately –60 degrees
Block: Left anterior fascicular block
Infarction: None
Interpretation: Normal sinus rhythm with left anterior fascicular block
Teaching point: There is left axis deviation without evidence of a complete bundle branch block. This should raise suspicion for a fascicular block. Note the rS pattern in leads II, III, and aVF, a qR pattern in leads I and aVL, and an axis more negative than –30 to –45 degrees. These findings are diagnostic of a left anterior fascicular block.
Rate: 108 bpm (Intrinsic rate 80 bpm, not accounting for ectopy)
Rhythm: Regularly irregular
Axis: Normal +30 degrees
Block: None
Infarction: None
Interpretation: Normal sinus rhythm with unifocal ventricular trigeminy
Teaching point
Stay updated, free articles. Join our Telegram channel
Full access? Get Clinical Tree
