Answer: Choice 4: Brugada Type 2

Explanation:

Brugada syndrome is a disorder characterized by sudden death associated with one of several ECG patterns characterized by incomplete right bundle-branch block and ST-segment elevations in the anterior precordial leads.

Type I: Lead V1 has a “coved” ST segment elevation of at least 2 millimeters, followed by a negative T wave.

Type II: There is a “saddleback” appearance of the ST segment in lead V1 with ST segment elevation of at least 2 millimeters; this can be present in normal individuals as well.,

Type III: Features of type I (coved) or type II (saddleback) with < 2 mm of ST segment elevation.,

These ECG changes can be provoked in the electrophysiology lab by infusing procainamide.,

The treatment for Brugada Syndrome is an ICD (implantable cardioverter defibrillator)

Brugada J, Campuzano O, Arbelo E, Sarquella-Brugada G, Brugada R. Present Status of Brugada Syndrome: JACC State-of-the-Art Review. J Am Coll Cardiol. 2018;72(9):1046-1059.

doi:10.1016/j.jacc.2018.06.037

Answer: Choice 2: Atrioventricular nodal reentrant tachycardia (AVNRT)

Explanation:

Atrioventricular nodal reentrant tachycardia (AVNRT), the most common form of supraventricular tachycardia, results from conduction through a reentrant circuit comprising fast and slow atrioventricular nodal pathways.

• In AVNRT the atrial activity is manifested by 'Discrete Retrograde P Waves'

• In Sinus Tachycardia the atrial activity is manifested by 'Discrete Anterograde P Waves'

• In Atrial Flutter the atrial activity is manifested by 'Regular Undulating waves

• In Ectopic Atrial Tachycardia the atrial activity is manifested by 'Discrete Modified P waves'

Catheter ablation is the treatment of choice for symptomatic patients with atrioventricular nodal re-entrant tachycardia (AVNRT). When the diagnosis of AVNRT is established, ablation should be only directed towards the anatomic position of the slow pathway.

Verapamil, diltiazem, and beta-blockers are options for the chronic management of AVNRT (Class IIa indication). 2019 ESC Guidelines for the Management of Patients With Supraventricular Tachycardia Eur Heart J 2020;41:655-720.

Gomes J.A. (2020) Atrioventricular Nodal Reentry. In: Heart Rhythm Disorders. Springer, Cham. https://doi.org/10.1007/978-3-030-45066-3_6

Answer: Multifocal Atrial Tachycardia

Explanation:

The characteristic EKG feature is variability in P wave morphology, with each unique P wave morphology felt to indicate a different site of atrial origin (N Engl J Med 1990; 322:1713-1717 DOI: 10.1056/NEJM199006143222405)

The term MAT was used as early as 1955 (N Engl J Med 1955; 252:928-933 DOI: 10.1056/NEJM195506022522202)

Patients with multiple P wave morphologies but a normal heart rate (60 to 100 beats per minute) are considered to have a wandering atrial pacemaker, since the heart rate does not meet criteria for a tachycardia. (Christopher V. DeSimone, Niyada Naksuk, Samuel J. Asirvatham. (2018) Supraventricular Arrhythmias: Clinical Framework and Common Scenarios for the Internist. Mayo Clinic Proceedings 93:12, 1825-1841)

Treatment of an underlying condition is recommended as a first step (Class I). Verapamil, diltiazem, or a selective beta-blocker should be considered (Class IIa). Atrioventricular (AV) nodal ablation followed by biventricular or His-bundle pacing should be considered for patients with left ventricular dysfunction due to recurrent multifocal AT refractory to drug therapy (Class IIa) (Brugada J, Katritsis DG, Arbelo E, et al. 2019 ESC Guidelines for the Management of Patients With Supraventricular Tachycardia: The Task Force for the management of patients with supraventricular tachycardia of the European Society of Cardiology (ESC): Developed in collaboration with the Association for European Pediatric and Congenital Cardiology (AEPC). Eur Heart J 2020;41:655-720)

https://www.ahajournals.org/doi/pdf/10.1161/01.CIR.42.3.397

Answer: Choice 2: Prolonged PR interval

Explanation:

The PR interval is prolonged ~432 msec

The PR interval is defined as the time from the onset of the P wave to the onset of the QRS complex (whether the first wave in this QRS complex is a Q wave or an R wave)

The PR interval measures the time required for an electrical impulse to travel from the atrial myocardium adjacent to the sinoatrial node to the ventricular myocardium adjacent to the fibers of the Purkinje network

The PR interval tends to increase with age. Normal PR interval in adults is from 140 to 210 msec, in adolescents from 120 to 160 msec and in childhood from 100 to

The major portion of the PR interval reflects the conduction of the impulse through the atrioventricular (AV) node and is therefore dependent on the balance between the sympathetic and parasympathetic tone

Therefore, the PR interval varies with heart rate, being longer with slower heart rates and vice versa

Answer: Choice 3: Mobitz Type 1 Heart Block

Explanation:

This patient has Mobitz Type 1 Heart Block or Wenckebach sequence in which the PR interval gradually lengthens with each successive beat until there is a failure to conduct an impulse and no ventricular beat is produced

There is progressive lengthening of the the PR interval because each successive atrial impulse arrives progressively earlier in the relative refractory period of the AV node, and therefore takes progressively longer to penetrate the node and reach the ventricles

Answer: Choice 2: Junctional Bradycardia

Explanation:

Bradyarrhythmias are usually sinus bradycardia, a junctional bradycardia or ventricular rhythm

The absence of regular P wave with narrow QRS complex suggests junctional bradycardia

Answer: Choice 2: Pericarditis

Explanation:

ST-segment elevation can most often be attributed to 3 specific causes:

1) a normal variant, frequently referred to as early repolarization, commonly characterized by J-point elevation and rapidly upsloping or normal ST segment;

2) injury currents associated with acute ischemia or ventricular dyskinesis; and

3) injury currents usually associated with pericarditis.

Because pericarditis usually involves the entire pericardium there is ST-segment elevation of all of the standard leads that are positive leftward and anteriorly & with ST depression in lead aVR

However, when pericarditis is localized ST segment elevation may occur only in a few leads

Depression of the PR segment was also present in half of a series of consecutive patients with acute pericarditis

Spodick DH. Differential characteristics of the electrocardiogram in early repolarization and acute pericarditis. N Engl J Med. 1976;295:523– 6.

Rautaharju PM, Surawicz B, Gettes LS. AHA/ACCF/HRS recommendations for the standardization and interpretation of the electrocardiogram: part IV: the ST segment, T and U waves, and the QT interval: a scientific statement from the American Heart Association Electrocardiography and Arrhythmias Committee, Council on Clinical Cardiology; the American College of Cardiology Foundation; and the Heart Rhythm Society. J Am Coll Cardiol 2009;53:982–91.

Answer: Choice 3: Hypothermia (body temperature < 35 ºC or < 95 ºF)

Explanation:

Although all options cause sinus bradycardia, this EKG in addition shows Osborn waves

Osborn or 'J' waves are upward deflections at the junction of the QRS complex and ST segment

The height of the Osborn waves is considered to be roughly proportional to the degree of hypothermia but recent papers have disputed this finding

J-waves are not specific to hypothermia and can be seen in other arrhythmogenic conditions including Brugada and malignant early repolarization syndromes.

In hypothermia all intervals of the EKG may lengthen including the RR, PR, QRS and QT intervals

Okada M et al. The J wave in accidental hypothermia. J Electrocardiol 1983;23-28

Hesham R Omar, Enrico M Camporesi. The correlation between the amplitude of Osborn wave and core body temperature. European Heart Journal: Acute Cardiovascular Care 2015 4:4, 373-377

Answer: Choice 4: Complete Heart Block

Explanation:

When no atrial impulses are no longer conducted to the ventricles, the cardiac rhythm is 'third-degree' heart block

The escape rhythm, whether junctional or ventricular escape rhythm, is almost always precisely regular because these sites are not as influenced by the parasympathetic/sympathetic balance as is the sinus node

This EKG shows ventricular escape (which occurs at a slower rate than junctional escape)

Answer: Choice 2: Ventricular Fibrillation

Explanation:

Neither QRS complexes nor T waves are clearly formed

The rhythm looks similar when viewed right-side up or upside down

The baseline is undulant

Answer: Choice 2: Ventricular Tachycardia

Explanation:

Wide QRS complex tachycardia with NORTHWEST axis (QRS complex negative in both lead 1 and in lead avF) suggests ventricular tachycardia

Answer: Choice 2: Left Ventricular Hypertrophy

Explanation:

This EKG meets several voltage criteria for LVH including

a) Soklow-Lyon criteria for LVH: 1) S in V1
+ R in V5 or V6 ≥ 35 mm OR R in V5 or V6 > 25 mm

b) R in V5 > 33 mm (Wilson FN, Johnston FD, Rosenbaum FF, et al. The precordial electrocardiogram. Am Heart J. 1944;27:19–85).

c) R in V6 > 25 mm (Wilson FN, Johnston FD, Rosenbaum FF, et al. The precordial electrocardiogram. Am Heart J. 1944;27:19–85).

The various criteria for LVH have different positive and negative predictive values in different patient populations, suggesting that the value of multiple criteria may be additive.

Hancock EW, Deal BJ, Mirvis DM, Okin P, Kligfield P, Gettes LS. AHA/ACCF/HRS recommendations for the standardization and interpretation of the electrocardiogram: part V: electrocardiogram changes associated with cardiac chamber hypertrophy: a scientific statement from the American Heart Association Electrocardiography and Arrhythmias Committee, Council on Clinical Cardiology; the American College of Cardiology Foundation; and the Heart Rhythm Society. J Am Coll Cardiol 2009;53:992–1002

Answer: Choice 2: Left Ventricular Hypertrophy

Explanation:

At the extreme left of this EKG the standardization shows 'half' standardization. Therefore, if normal standardization is used then this EKG meets voltage criteria for LVH

Using normal standardization, 10 mm (10 small boxes) equals 1 mV; 1 mm equals 0.1 mV.)

When the wave forms are very large, half standard may be used (5 mm equals 1 mv).

It is important prior to reading each EKG that the reader determines whether the standardization is calibrated normally. Paper speed and voltage are usually printed on the bottom of the ECG

Answer: Choice 3: Neither of the chambers are enlarged

Explanation:

At the extreme left of this EKG, the standardization shows double standard (20 mm equals 1 mv)

Using normal standardization, 10 mm (10 small boxes) equals 1 mV; 1 mm equals 0.1 mV.)

When the waveforms are small, the EKG machine automatically uses double standard (like in this EKG) to 'magnify' the EKG

Therefore, before applying voltage criteria it is important to check whether the calibration is at the usual 10 mm

Answer: Choice 1: Right Axis Deviation

Explanation:

The mean frontal plane electrical axis, determined by the vector of the maximal (dominant) QRS deflection, depends on age and body habitus

It shifts to the left with increasing age.

In adults, the normal QRS axis is considered to be within 30° and 90°.

Moderate right-axis deviation in adults is from 90° to 120°

Marked right-axis deviation, which is often associated with left posterior fascicular block, is between 120° and 180°.

In the absence of a dominant QRS deflection, as in an equiphasic QRS complex, the axis is said to be indeterminate.

Surawicz B, Childers R, Deal BJ, Gettes LS. AHA/ACCF/HRS recommendations for the standardization and interpretation of the electrocardiogram, part III: intraventricular conduction disturbances: a scientific statement from the American Heart Association Electrocardiography and Arrhythmias Committee, Council on Clinical Cardiology; the American College of Cardiology Foundation; and the Heart Rhythm Society. Circulation. 2009;119:e235–e240

https://www.ahajournals.org/doi/10.1161/CIRCULATIONAHA.108.191095

Answer: Choice 2: Left Axis Deviation

Explanation:

The mean frontal plane electrical axis, determined by the vector of the maximal (dominant) QRS deflection, depends on age and body habitus

It shifts to the left with increasing age.

In adults, the normal QRS axis is considered to be within 30° and 90°.

Left-axis deviation is 30° and beyond.

Moderate left-axis deviation is between 30° and 45°.

Marked left-axis deviation is from 45° to 90° and is often associated with left anterior fascicular block.

Surawicz B, Childers R, Deal BJ, Gettes LS. AHA/ACCF/HRS recommendations for the standardization and interpretation of the electrocardiogram, part III: intraventricular conduction disturbances: a scientific statement from the American Heart Association Electrocardiography and Arrhythmias Committee, Council on Clinical Cardiology; the American College of Cardiology Foundation; and the Heart Rhythm Society. Circulation. 2009;119:e235–e240

https://www.ahajournals.org/doi/10.1161/CIRCULATIONAHA.108.191095

Answer: Choice 3: Complete Left Bundle Branch Block

Explanation:

QRS duration ≥ to 120 ms in adults, > 100 ms in children 4 to 16 years of age, and > 90 ms in children < 4 years of age.

Broad notched or slurred R wave in leads I, aVL, V5, and V6 and an occasional RS pattern in V5 and V6 attributed to displaced transition of QRS complex.

Absent q waves in leads I, V5, and V6, but in the lead aVL, a narrow q wave may be present in the absence of myocardial pathology.

R peak time > 60 ms in leads V5 and V6 but normal in leads V1, V2, and V3, when small initial r waves can be discerned in the above leads.

ST and T waves usually opposite in direction to QRS.

Positive T wave in leads with upright QRS may be normal (positive concordance).

Surawicz B, Childers R, Deal BJ, Gettes LS. AHA/ACCF/HRS recommendations for the standardization and interpretation of the electrocardiogram, part III: intraventricular conduction disturbances: a scientific statement from the American Heart Association Electrocardiography and Arrhythmias Committee, Council on Clinical Cardiology; the American College of Cardiology Foundation; and the Heart Rhythm Society. Circulation. 2009;119:e235–e240.

https://www.ahajournals.org/doi/10.1161/CIRCULATIONAHA.108.191095

Answer: Choice 3: Complete Right Bundle Branch Block

Explanation:

QRS duration ≥ 120 ms in adults, > 100 ms in children ages 4 to 16 years, and > 90 ms in children less than 4 years of age.

rsr, rsR, or rSR in leads V1 or V2. The R or r deflection is usually wider than the initial R wave. In a minority of patients, a wide and often notched R wave pattern may be seen in lead V1 and/or V2.

S wave of > duration than R wave or > than 40 ms in leads I and V6 in adults.

Normal R peak time in leads V5 and V6 but 50 ms in lead V1.

Of the above criteria, the first 3 should be present to make the diagnosis of complete RBBB.

When a pure dominant R wave with or without a notch is present in V1, criterion 4 should be satisfied.

Surawicz B, Childers R, Deal BJ, Gettes LS. AHA/ACCF/HRS recommendations for the standardization and interpretation of the electrocardiogram, part III: intraventricular conduction disturbances: a scientific statement from the American Heart Association Electrocardiography and Arrhythmias Committee, Council on Clinical Cardiology; the American College of Cardiology Foundation; and the Heart Rhythm Society. Circulation. 2009;119:e235–e240.

https://www.ahajournals.org/doi/10.1161/CIRCULATIONAHA.108.191095

Answer: Choice 1: Right Ventricular Outflow Tachycardia

Explanation:

The wide complex tachycardia indicates ventricular tachycardia

The negative QRS complex in lead V1 and V2 with a left bundle branch pattern in lead V6 suggests that it arises from the right ventricle

The positive QRS complexes in inferior limb leads II, III and aVF suggests that it arises from the outflow tract--i.e., the right ventricular outflow tract

Answer: Choice 2: Type B Wolff-Parkinson-White Pattern

Explanation:

PR interval < 120 ms (assuming no intra-atrial or interatrial conduction block) during sinus rhythm in adults and less than 90 ms in children.

Slurring of initial portion of the QRS complex (delta wave), which either interrupts the P wave or arises immediately after its termination

QRS duration > 120 ms in adults and > 90 ms in children.

Secondary ST and T wave changes.

Wolff­-Parkinson­-White pattern has been classified into two types (Type A or Type B) according to the ECG morphology of the precordial leads

In type B, the delta wave and QRS complex are predominantly negative in leads V1 and V2 and positive in the other precordial leads, resembling left bundle branch block

In type A, the delta wave and QRS complex are predominantly upright in the precordial leads. The dominant R wave in lead V1 may be misinterpreted as right bundle branch block, RVH or posterior MI

Answer: Type A Wolff-Parkinson-White pattern

Explanation:

PR interval < 120 ms (assuming no intra-atrial or interatrial conduction block) during sinus rhythm in adults and less than 90 ms in children.

Slurring of initial portion of the QRS complex (delta wave), which either interrupts the P wave or arises immediately after its termination.

QRS duration > 120 ms in adults and > 90 ms in children.

Secondary ST and T wave changes.

Wolff­-Parkinson­-White pattern has been classified into two types (Type A or Type B) according to the ECG morphology of the precordial leads

In type A, the delta wave and QRS complex are predominantly upright in the precordial leads. The dominant R wave in lead V1 may be misinterpreted as right bundle branch block, RVH or posterior MI

In type B, the delta wave and QRS complex are predominantly negative in leads V1 and V2 and positive in the other precordial leads, resembling left bundle branch block

Answer: Choice 1: Torsades de Pointes

Explanation:

Torsades de Pointes is a type of ventricular tachycardia with variations in morphology

This French term translates into 'twisting of the points"

The waveforms are neither characteristic of QRS complexes nor T waves and the rate varies from 180 to 250 beats per minute

It is usually non-sustained

It may evolve into ventricular fibrillation

Prevention of Torsade de Pointes in Hospital SettingsA Scientific Statement From the American Heart Association and the American College of Cardiology Foundation Endorsed by the American Association of Critical-Care Nurses and the International Society for Computerized Electrocardiology, American Heart Association Acute Cardiac Care Committee of the Council on Clinical Cardiology, Council on Cardiovascular Nursing, American College of Cardiology Foundation. Journal of the American College of Cardiology March 02, 2010, 55 (9) 934-947

Answer: Choice 2: This EKG shows bidirectional tachycardia (VT), alternating left- and right-axis deviation, is usually seen in digitalis toxicity

Explanation:

An important differential diagnosis of this rare ventricular arrhythmia is catecholaminergic polymorphic VT, which can manifest as bidirectional.

However, the clinical circumstance of exercise- or stress-induced tachycardia in a usually young individual without structural heart disease points to the correct diagnosis.

The proposed arrhythmia mechanism is triggered activity arising alternately from the left anterior and posterior fascicle. This results in an alternating left and right frontal-plane axis, giving rise to a typical “bidirectional” appearance

Answer: Choice 2: Mid-RCA occlusion

Explanation:

ST elevation in lead III > lead II suggests RCA occlusion -- suggests injury of the inferior wall of the LV

ST depression in chest leads V1 and V2 suggests mid RCA occlusion -- suggesting epicardial injury also involves the lateral aspects of the LV

Reference: Table 10.7: Infarction Terminology Relationships: Marriott's Practical Electrocardiography, eleventh edition by Galen S. Wagner, Lippincott Williams and Wilkins, 2008, ISBN-13: 9780781797382

Answer: Choice 4: Left Circumflex (LCx) Coronary Artery

Explanation:

When the LCx is occluded, the spatial vector of the ST segment in the frontal plane is more likely to be directed to the left than when the RCA is occluded. For this reason, the ST segment may be elevated to a greater extent in lead II than in lead III and may be isoelectric or elevated in leads 1 and aVL

ST-segment elevation in I, aVL, V5 to V6 is also seen with LCx occlusion

Bairey CN, Shah PK, Lew AS, Hulse S. Electrocardiographic differentiation of occlusion of the left circumflex versus the right coronary artery as a cause of inferior acute myocardial infarction. Am J Cardiol. 1987; 60: 456–69

Baliga RR, Bahl VK, Alexander T, et al. Management of STEMI in low- and middle-income countries. Glob Heart. 2014;9(4):469-510

https://www.ahajournals.org/doi/full/10.1161/CIRCULATIONAHA.108.191098

https://www.sciencedirect.com/science/article/pii/S2211816014026684?via%3Dihub

Answer: Choice 1: Right Coronary Artery

Explanation:

Inferior wall infarction that results in ST-segment elevation in only leads II, III, and aVF may be the result of occlusion of either the right coronary artery (RCA) or the left circumflex coronary artery (LCx), depending on which provides the posterior descending branch, that is, which is the dominant vessel.

When the RCA is occluded, the spatial vector of the ST segment will usually be directed more to the right than when the left circumflex is occluded. This will result in greater ST segment elevation in lead III than in lead II and will often be associated with ST-segment depression in leads I and aVL, leads in which the positive poles are oriented to the left and superiorly

It is not possible to determine whether the RCA or LCx vessel is occluded when changes of inferior wall ischemia/ infarction are accompanied by depression of the ST segment in leads V1, V2, and V3; however, the absence of such changes is more suggestive of RCA than LCx occlusion.

Zimetbaum PJ, Krishnan S, Gold A, et al. Usefulness of ST-segment elevation in lead III exceeding that of lead II for identifying the location of the totally occluded coronary artery in inferior wall myocardial infarction. Am J Cardiol. 1998; 81: 918–9.

Herz I, Assali AR, Adler Y, et al. New electrocardiographic criteria for predicting either the right or left circumflex artery as the culprit coronary artery in inferior wall acute myocardial infarction. Am J Cardiol. 1997; 80: 1343–5.

https://www.ahajournals.org/doi/full/10.1161/CIRCULATIONAHA.108.191098

Answer: Choice 1: Distal LAD occlusion

Explanation:

When the occlusion is located more distally, that is, below both the first septal and first diagonal branches, the basal portion of the left ventricle will not be involved, and the ST-segment vector will be oriented more inferiorly.

Therefore, the ST segment will not be elevated in leads V1, aVR, or aVL, and the ST segment will not be depressed in leads II, III, or aVF

Indeed, because of the inferior orientation of the ST-segment vector, elevation of the ST segment in leads II, III, and aVF is seen

Moreover, ST-segment elevation may be more prominent in leads V3 through V6 and less prominent in V2 than in the more proximal occlusions

Engelen DJ, Gorgels AP, Cheriex EC, et al. Value of the electrocardiogram in localizing the occlusion site in the left anterior descending coronary artery in acute anterior myocardial infarction. J Am Coll Cardiol. 1999; 34: 389–95

https://www.ahajournals.org/doi/full/10.1161/CIRCULATIONAHA.108.191098

Answer: Choice 3: LAD occlusion

Explanation:

When the LAD occlusion is located between the first septal and first diagonal branches, the basal interventricular septum will be spared, and the ST segment in lead V1 will not be elevated.

In this situation, the ST-segment vector will be directed toward aVL, which will be elevated, and away from the positive pole of lead III, which will show depression of the ST segment

https://www.ahajournals.org/doi/full/10.1161/CIRCULATIONAHA.108.191098

Answer: Choice 3: Mid to Distal LAD Coronary Artery

Explanation:

This EKG shows anteroseptal infarction as evidenced by ST elevation in V1-V3

This pattern suggests occlusion of the mid to distal LAD

Anterior wall ischemia/infarction is invariably due to occlusion of the LAD coronary artery and results in the spatial vector of the ST segment being directed to the left and laterally.

This will be expressed as ST elevation in some or all of leads V1 through V6.

Answer: Choice 3: Occlusion of Proximal LAD

Explanation:

Anterior wall ischemia/infarction is invariably due to occlusion of the LAD coronary artery and results in the spatial vector of the ST segment being directed to the left and laterally

This will be expressed as ST elevation in some or all of leads V1 through V6

The location of the occlusion within the LAD coronary artery, that is, whether proximal or distal, is suggested by the chest leads in which the ST-segment elevation occurs and the presence of ST-segment elevation or depression in other leads

Occlusion of the proximal LAD coronary artery above the first septal and first diagonal branches results in involvement of the basal portion of the left ventricle, as well as the anterior and lateral walls and the interventricular septum

This will result in the ST-segment spatial vector being directed superiorly and to the left and will be associated with ST-segment elevation in leads V1 through V4, I, aVL, and often aVR.

It will also be associated with reciprocal ST-segment depression in the leads whose positive poles are positioned inferiorly, that is, leads II, III, aVF, and often V5

Typically, there will be more ST elevation in aVL than in aVR and more ST-segment depression in lead III than in lead II, because the ST-segment spatial vector will be directed more to the left than to the right

AHA/ACCF/HRS recommendations for the standardization and interpretation of the electrocardiogram: part VI: acute ischemia/infarction Circulation. 2009 Mar 17;119(10):e262-70

https://www.ahajournals.org/doi/full/10.1161/CIRCULATIONAHA.108.191098

Answer: Choice 1: Left Main Coronary Artery occlusion resulting in extensive anterolateral ischemia/infarct

Explanation:

Elevation in leads aVR and V1 with global ST-segment depressions suggests left main coronary artery occlusion; particularly because ST elevation in aVR > V1

AHA/ACCF/HRS recommendations for the standardization and interpretation of the electrocardiogram: part VI: acute ischemia/infarction Circulation. 2009 Mar 17;119(10):e262-70

https://www.ahajournals.org/doi/full/10.1161/CIRCULATIONAHA.108.191098

https://www.ncbi.nlm.nih.gov/pubmed/25592801

Answer: Choice 2: Atrial Flutter; this EKG also shows PVCs or aberrantly conducted complexes

Explanation:

The F waves of atrial flutter are typically between 200 and 350 bpm

In coarse fibrillation prominent f waves are clearly seen in many leads of the EKG

Whereas, in fine atrial fibrillation either there are small f waves or no visible atrial activity

Answer: Choice 3: Brugada Syndrome--Type 2 pattern

Explanation:

The term Brugada pattern to describe a pattern that simulates incomplete RBBB in lead V1 with ST-segment changes

In borderline ECG changes the pattern can be elicited by infusion of sodium channel blocking drugs such as procainamide

Three are 3 types of Brugada ECG patterns:

(1) Type 1 typically shows coved ST segment elevation and inverted T waves in V1 to V3,

(2) Types 2 & 3 are associated with saddle-back morphology where ST segment descends towards the baseline but then rises again with biphasic or upright T waves.

(3) Type 2 Brugada shows ST elevation greater than than 1 mm whereas Type 3 pattern the ST elevation is less than 1 mm

Answer: Choice 4: Third Degree Heart Block (with ventricular escape rhythm)

Explanation:

When no atrial impulses are conducted to the ventricles, the rhythm is termed 'Third Degree Heart Block'

The escape rhythm may be junctional or ventricular and is usually regular because these sites are not influenced by sympathetic/parasympathetic balance as in the in the sinus node

Answer: Choice 2: Junctional Tachycardia

Explanation:

Narrow QRS complexes with HR>100 bpm and not preceded by P waves. In this patient this P waves follow the QRS complex

Answer: Choice 1: Accelerated Junctional Rhythm

Explanation:

Accelerated Junctional Rhythm is apparent from the frequent, regular 'narrow' QRS complex not preceded by P waves. In this EKG, P waves follow the QRS complex

In Accelerated Ventricular Rhythm the rhythm is apparent from frequent, regular, 'wide' QRS complexes not preceded by P waves

Answer: Choice 1: AV Nodal Re-Entrant Tachycardia

Explanation:

There are discrete retrograde P waves between the QRS complex and T wave

Answer: Choice 3: Ectopic Atrial Tachycardia

Explanation:

Discrete modified P waves in both limb and chest leads

Answer: Choice 2: Sinus Tachycardia

Explanation:

Ectopic Atrial Tachycardia -------------- Discrete Modified P waves

Sinus Tachycardia ------------------------ Discrete Anterograde P waves

AV Nodal Re-Entrant Tachycardia ------- Discrete Retrograde P waves

Atrial Flutter ------------------------- Regular Undulating Waves

Answer: Choice 3: Atrial Flutter

Explanation:

The typical 'saw-tooth' appearance of F waves is seen in this rhythm strip and is typically seen in inferior leads

Atrial Flutter is seen more often seen with ischemic disease and is relatively uncommon in mitral valve disease

Answer: Choice 2: LVH

Explanation:

The patient meets the voltage criteria for LVH, i.e., R in aVL > 11 mm

This EKG also meets another voltage criteria, i.e, R in lead I + S in lead III >25 mm

The sensitivity of both these criteria is similar, ~11%

The various criteria have different positive and negative predictive values in different patient populations (suggesting that the value of multiple criteria may be additive

The commonly applied voltage criteria apply to adults > 35 years of age

Voltage criteria standards for the 16- to 35-year age group are not as well established, and therefore, the diagnosis of LVH based on voltage alone has a low accuracy in this age group

AHA/ACCF/HRS recommendations for the standardization and interpretation of the electrocardiogram: part V: electrocardiogram changes associated with cardiac chamber hypertrophy: . J Am Coll Cardiol 2009;53:992–1002.

http://www.onlinejacc.org/content/53/11/992

Answer: Choice 4: Juvenile T waves

Explanation:

In adolescents >12 years of age and in young adults < 20 years of age, the T wave may be slightly inverted in aVF, inverted in lead V2 and occasionally in V3

In adults >20 years old, the normal T wave is inverted in aVR; upright or inverted in leads aVL, III, and V1; and upright in leads I and II and in chest leads V3 through V6.

AHA/ACCF/HRS recommendations for the standardization and interpretation of the EKG: part IV: the ST segment, T and U waves, and the QT interval . J Am Coll Cardiol. 2009;53(11):982.

https://www.sciencedirect.com/science/article/pii/S0735109708041363?via%3Dihub

Answer: Choice 2: Left Ventricular Hypertrophy

Explanation:

This patient has LVH as evidenced by Cornell Voltage Criteria for LVH.

In Females: R wave in lead aVL + S in lead V3 > 20 mm

In Males: R wave in lead aVL + S in lead V3 > 28 mm

The sensitivity of the Cornell Voltage criteria is 42% and specificity is ~96%.

The sensitivity of EKG voltage criteria for LVH is less than 50% (although specificity is high). Because of differences in specificity and sensitivity of different criteria patients who meet one criteria often does not meet another set of criteria for LVH.

In one study only 11% of patients met both Cornell Voltage criteria and Sokolow-Lyon Criteria for LVH

Sokolow Lyon Criteria: S in lead V1 + R in lead V5 or V6 ≥ 35 mm or R in lead V5 or V6 ≥ 26 mm . It is reported that these criteria have sensitivity of only 22% with a specificity of 100% (Circulation 1987;75:565)

Criteria should be adjusted for factors known to alter accuracy, including gender, race, and body habitus, when such criteria have been validated.

No single diagnostic criterion can be recommended for use compared with the others.

https://www.ahajournals.org/doi/pdf/10.1161/CIRCULATIONAHA.108.191097

Answer: 2: Hyperkalemia

Explanation:

The T wave is remarkable for the narrow shape due to an abbreviated depolarization time. This change is suggestive of hyperkalemia. While the T wave of hyperkalemia is often peaked, it is always narrow, and frequently not peaked.

Hyperkalemia triggers a progression of EKG changes, beginning with peaked T waves and PR prolongation. More severe elevations in serum potassium levels can result in QRS widening and flattening/loss of P waves, with eventual formation of the sine-wave pattern. The rhythm can degenerate into ventricular fibrillation if the cardiac membrane is not stabilized.

It must be remembered that there may be poor correlation between serum potassium levels and typical EKG changes of hyperkalemia

Surawicz B. Relationship between electrocardiogram and electrolytes. Am Heart J 1967;73:814-834

Ettinger PO, Regan TJ, Olderwurtel HA. Hyperkalemia, cardiac conduction and the electrocardiogram. A review. Am Heart J 1974;58;160-171

Answer: 5: Ectopic Atrial Bradycardia

Explanation:

The P wave is inverted in leads II, III, aVF & chest leads suggesting that the arrhythmia originates outside the sinus node and in the atria

When heart rate is less than 50 beats per minute then suspect sinus node dysfunction

http://www.onlinejacc.org/content/early/2018/10/29/j.jacc.2018.10.044?_ga=2.186953256.1060670576.1544828938-774281285.1520756046

Answer: 2: Lateral Injury or lateral myocardial infarction (LMI)

Explanation:

This EKG shows ST elevation in leads aVL and lead I with reciprocal changes in leads III, and aVT

The lateral leads are chest leads V4-6, limb leads I and aVL with reciprocal ST depressions present in limb leads III and aVF.

The lateral wall of the left ventricle is supplied by branches of the left anterior descending (LAD) and left circumflex (LCx) arteries

There are 3 broad patterns of lateral injury/infarction. (1) Anterolateral: caused by occlusion of the LAD. (2) Inferior-posterior-lateral: caused by occlusion of the LCx. (3) Isolated lateral infarction: due to infarction of smaller vessels such as diagonal, obtuse marginal(OM) or ramus intermedius.

Coding Pointer: ST elevation is coded as 'suggestive of myocardial injury' whereas ST depression is coded as 'suggestive of myocardial ischemia' & pathologic Q waves (duration >0.04 seconds) as 'infarction'.

ST elevation/injury should be considered as primary event and when Q waves are present, infarction should also be coded

Answer: 1: AVNRT

Explanation:

Atrioventricular nodal reentry tachycardia (AVNRT) is the most common type of reentrant supraventricular tachycardia (SVT) & arises from a level above the Bundle of His.

The substrate for AVNRT is the presence of dual AV nodal pathways: the fast pathway and the slow pathway, which are both in the right

Like most SVTs, the QRS complex in AVNRT is usually narrow (ie, ≤120 milliseconds), reflecting normal ventricular activation through the His-Purkinje system, although aberrant conduction (eg, underlying bundle branch block) can result in a wide QRS complex

The P wave that occurs after the QRS complex (a short RP interval)

EKG courtesy Dr. Joseph Marine, MD, Vice-Director, Johns Hopkins Division of Cardiology

https://www.hopkinsmedicine.org/profiles/results/directory/profile/0019424/joseph-marine

Answer: Choice 2: Brugada Syndrome--Type 1 pattern

Explanation:

The term Brugada pattern to describe a pattern that simulates incomplete RBBB in lead V1 with ST-segment changes

In borderline ECG changes the pattern can be elicited by infusion of sodium channel blocking drugs such as procainamide

Three are 3 types of Brugada ECG patterns: (1) Type 1 typically shows coved ST segment elevation and inverted T waves in V1 to V3,

(2) Types 2 & 3 are associated with saddle-back morphology where ST segment descends towards the baseline but then rises again with biphasic or upright T waves.

(3) Type 2 Brugada shows ST elevation greater than than 1 mm whereas Type 3 pattern the ST elevation is less than 1 mm.

Answer: Choice 2: Atrial Tachycardia

Explanation:

The P wave is inverted in leads II, III, aVF & chest leads suggesting that the arrhythmia originates outside the sinus node and in the atria.

Atrial tachycardia happens when a site outside of the sinus node, but within the atria, creates action potentials faster than the sinus node. This ectopic focus becomes the predominant pacemaker of the heart. When the atrial rate is greater than 100 beats per minute, the rhythm is atrial tachycardia.

The narrow QRS complex suggests that the origin of the tachycardia is not below the AV node

EKG courtesy by Dr. Joseph E. Marine, MD, Vice-Chair, Division of Cardiology, Johns Hopkins

https://www.hopkinsmedicine.org/profiles/results/directory/profile/0019424/joseph-marine

Answer: Choice 4: Mobitz Type 1 Heart Block

Explanation:

Type 1 (Wenckebach) AV block is owing to depressed AV nodal conduction and is recognized by a prolonging PR interval ending in a "dropped beat."

EKG courtesy Dr Brad Knight, MD, the Chester C. and Deborah M. Cooley Distinguished Professor of Cardiology at Northwestern University, and has been the Director of Cardiac Electrophysiology at the Bluhm Cardiovascular Institute at Northwestern Memorial Hospital since November 1, 2009 https://www.feinberg.northwestern.edu/faculty-profiles/az/profile.html?xid=18543

Hay Heart Block : https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6655013/pdf/CLC-23-869.pdf

Answer: Choice 3: Complete Heart Block above Bundle of His

Explanation:

In complete heart block there is no atrioventricular conduction. The ventricular escape mechanism can occur anywhere from the atrioventricular node to the bundle-branch Purkinje system. The narrow QRS complex suggests that the block is above the His bundle

The electrocardiogram in complete heart block can be divided into 2 groups: (1) those with very slow ventricular rate and widened QRS complex, and this group is more likely to have Stokes-Adams attacks. The wide QRS complex suggests that the heart block is at or below the bundle of His (2) those who have normal QRS complex and faster ventricular rate, usually over 40 beats/min. The narrow QRS complex suggest that the heart block is usually above the bundle of His

EKG features of complete heart block include (1) Regular P-P interval (2) Regular R-R interval (3) Lack of an apparent relationship between the P waves and QRS complexes (4) More P waves are present than QRS complexes

http://www.onlinejacc.org/content/early/2018/10/29/j.jacc.2018.10.044?_ga=2.186953256.1060670576.1544828938-774281285.1520756046

Answer: Choice 3: Right Ventricular Hypertrophy (including RBBB and Left Posterior Fascicular Block)

Explanation:

Numerous Criteria for RVH have been proposed include:- 1. Right axis deviation of +110° or more. 2. Dominant R wave in V1 (> 7mm tall or R/S ratio > 1). 3. Dominant S wave in V5 or V6 (> 7mm deep or R/S ratio < 1). 4. QRS duration < 120ms (i.e. changes not due to RBBB).

Supporting Criteria include:- 1. Right atrial enlargement (P pulmonale). 2. Right ventricular strain pattern = ST depression / T wave inversion in the right precordial (V1-4) and inferior (II, III, aVF) leads. 3. S1 S2 S3 pattern = far right axis deviation with dominant S waves in leads I, II and III. 4. Deep S waves in the lateral leads (I, aVL, V5-V6).

Accompanying features include: RBBB

"The sensitivity of the electrocardiographic criteria for RVH is generally low, some criteria have high specificity and can be used to advantage in diagnostic schemes or to derive continuous variables. The greatest accuracy is in congenital heart disease, with intermediate accuracy in acquired heart disease and

↵ Hancock E.W., Deal B.J., Mirvis D.M., et al. (2009) AHA/ACCF/HRS recommendations for the standardization and interpretation of the electrocardiogram: part V: electrocardiogram changes associated with cardiac chamber hypertrophy: a scientific statement from the American Heart Association Electrocardiography and Arrhythmias Committee, Council on Clinical Cardiology; the American College of Cardiology Foundation; and the Heart Rhythm Society: endorsed by the International Society for Computerized Electrocardiology. J Am Coll Cardiol 53:992–1002.

http://www.onlinejacc.org/content/53/11/992?ijkey=a0d76e598f09c95144ab6408e37ae025ccbb192f&keytype2=tf_ipsecsha

Answer: Choice 5: Pre-excitation

Explanation:

The EKG shows a short PR interval and a delta wave (a delta wave is slow slurred slow rise of QRS complex) indicating the patient has Wolff-Parkinson-White (WPW) pattern. WPW affects between 1 and 3 of every 1,000 people worldwide. It has been linked to Ebstein's anomaly

The following criteria are suggestive of full preexcitation: * PR interval (assuming no intra-atrial or interatrial conduction block) less than 120 ms during sinus rhythm in adults and less than 90 ms in children. * Slurring of initial portion of the QRS complex (delta wave), which either interrupts the P wave or arises immediately after its termination. *QRS duration greater than 120 ms in adults and greater than 90 ms in children. * Secondary ST and T wave changes.

AHA/ACCF/HRS Recommendations for the Standardization and Interpretation of the Electrocardiogram. Circulation. 2009;119:e235–e240

Wolff L, Parkinson J, White PD. Bundle-branch block with short P-R interval in healthy young people prone to paroxysmal tachycardia.Am Heart J. 1930; 5:685–704. In this article Wolff et al. acknowledged similar individual cases reported by Wilson in 1915, Wedd in 1921, and Hamburger in 1929

https://www.ahajournals.org/doi/10.1161/CIRCULATIONAHA.108.191095

Answer: Choice 5: 2:1 Second Degree Heart Block

Explanation:

Conduction ratio of 2: 1

The PR interval of conducted beat is constant

(Kusumoto FM et al. 2018 ACC/AHA/HRS guideline on the evaluation and management of patients with bradycardia and cardiac conduction delay: a report of the ACC/AHA Task Force on Clinical Practice Guidelines and the Heart Rhythm Society. J Am Coll Cardiol. Nov 2018)

https://www.acc.org/latest-in-cardiology/ten-points-to-remember/2018/11/05/15/12/2018-acc-aha-hrs-guideline-on-bradycardia