Cardiology Practice Questions

Q: The ECG shows a heart rate of 40 bpm, left axis deviation, and QRS duration >120 msec. There are deep monophasic S waves in V1-V3, broad monophasic R waves in lateral leads I, aVL, V5-V6, and absent Q waves in lateral leads with M shaped notch in peak of R wave in V5-V6. What is the diagnosis?

LBBB. ***LBBB*** - The ECG criteria for **LBBB** include a **QRS duration >120 msec** (broad QRS), a **broad, monophasic R wave** or "M-shaped" R wave (sometimes called rabbit ears) in **lateral leads (I, aVL, V5-V6)** signifying delayed activation of the left ventricle, and **deep S waves in V1-V3**. - The presence of **left axis deviation** can also be associated with LBBB, although not a primary diagnostic criterion. The absence of Q waves in lateral leads further supports delayed septal activation. *RBBB* - **RBBB** is characterized by a widened QRS complex (>120 msec) with an **RSR' pattern (M-shaped)** in leads **V1 and V2**, representing delayed right ventricular activation. - It typically presents with a **wide, slurred S wave in lateral leads (I, aVL, V5-V6)**, which is opposite to the findings described in the question. *Left anterior fascicular block* - **Left anterior fascicular block (LAFB)** is characterized by **left axis deviation (usually -45 to -90 degrees)** and a **normal QRS duration** (<120 msec), along with an absent Q wave and tall r wave in aVL, and a qR pattern in lead I. - It does not involve significant QRS widening or the specific morphology (broad R waves in lateral leads, deep S waves in V1-V3) seen in this ECG. *Left posterior fascicular block* - **Left posterior fascicular block (LPFB)** is rare and is characterized by **right axis deviation** and a **normal QRS duration** (<120 msec). - It does not present with the specific wide QRS and characteristic QRS morphology in precordial and lateral leads observed in this ECG tracing.

Q: A 30-year-old lady with scleroderma presents with progressive dyspnea on exertion. Which of the following is incorrect about the ECG finding?

Heart rate of 75 bpm. ***Heart rate of 75 bpm*** - This ECG shows a heart rate of approximately 100 bpm (one large box is 0.2 seconds; 300/3 = 100). Therefore, a heart rate of 75 bpm is **incorrect**. - The rhythm is generally regular, and the calculation of heart rate involves counting the number of R waves in a 6-second strip and multiplying by 10, or by dividing 300 by the number of large squares between R waves. *Right axis deviation* - The QRS complex in lead I is predominantly negative, and in aVF it is predominantly positive, which indicates **right axis deviation**. - Right axis deviation suggests possible **right ventricular hypertrophy** or strain, consistent with pulmonary hypertension which can occur in scleroderma. *T wave inversion in V1-V3* - The ECG clearly shows **T-wave inversions** in leads V1, V2, and V3. - This pattern can be suggestive of **right ventricular strain** or hypertrophy, commonly seen in pulmonary hypertension. *rSR' pattern in V1* - In lead V1, there is a small initial r wave, followed by an S wave, and then a larger R' wave, forming an **rSR' pattern**. - This morphology is characteristic of an **incomplete right bundle branch block (IRBBB)**, which is often associated with right ventricular volume or pressure overload, such as in pulmonary hypertension.

Q: What is the cardiac axis in the ECG provided?

Left axis deviation. ***Left axis deviation*** - The QRS complex in **lead I** is predominantly **positive**, and in **lead aVF** is predominantly **negative**. This combination indicates left axis deviation. - Also, the QRS complex in **lead II** is predominantly **negative**, which further confirms left axis deviation. *Normal axis* - A **normal axis** would show a predominantly **positive QRS** complex in both **lead I** and **lead aVF**. - In this ECG, lead aVF shows a predominantly negative QRS, ruling out normal axis. *Right axis deviation* - **Right axis deviation** is characterized by a predominantly **negative QRS** in **lead I** and a predominantly **positive QRS** in **lead aVF**. - This ECG shows a positive QRS in lead I, which contradicts right axis deviation. *Extreme axis deviation* - **Extreme axis deviation**, also known as "northwest axis," occurs when the QRS complex is predominantly **negative** in both **lead I** and **lead aVF**. - In this ECG, lead I is positive, ruling out extreme axis deviation.

Q: What is the axis in the ECG provided?

Left axis deviation. ***Left axis deviation*** - The **QRS complex** is predominantly **positive in Lead I** and predominantly **negative in Lead aVF**. - This combination indicates that the mean QRS electrical vector lies between **-30° and -90°**, which is characteristic of left axis deviation. *Normal* - A **normal axis** typically shows a predominantly **positive QRS complex** in both Lead I and Lead aVF. - This ECG shows a negative QRS in aVF, ruling out a normal axis. *Right axis deviation* - **Right axis deviation** is characterized by a predominantly **negative QRS complex** in Lead I and a predominantly **positive QRS complex** in Lead aVF. - This ECG shows the opposite pattern in Lead I (positive), ruling out right axis deviation. *Extreme axis deviation* - **Extreme axis deviation**, sometimes called "northwest axis," is present when the **QRS complex** is predominantly **negative in both Lead I and Lead aVF**. - In this ECG, Lead I is positive, so extreme axis deviation is not present.

Q: A 50-year-old woman with rheumatic heart disease is on medication for heart disease. She feels unwell for most part of the day. Which of the following medicine is responsible for the ECG changes shown below? (Recent NEET Pattern 2016-17)

Digoxin. ***Digoxin*** - The ECG shows changes characteristic of **digoxin toxicity**, specifically **downsloping ST depressions (scooping)** and **flattened or inverted T waves**, particularly in leads with dominant R waves. - The patient's symptoms of feeling "unwell for most part of the day" are consistent with **digoxin toxicity**, which can include nausea, fatigue, and cardiac arrhythmias. *ACE inhibitor* - ACE inhibitors primarily affect the **renin-angiotensin-aldosterone system** and do not typically cause these specific ECG changes. - Common side effects include cough and **hyperkalemia**, not the "scooped" ST segments seen here. *Diuretics* - Diuretics can cause **electrolyte imbalances**, such as hypokalemia, which might manifest as **flattened T waves** or **prominent U waves** on ECG, but not the characteristic "scooped" ST depression. - The symptoms of malaise are non-specific and while possible with electrolyte disturbances, the specific ECG pattern points away from diuretics as the primary cause. *Ivabradine* - Ivabradine is a **selective If channel inhibitor** that primarily reduces heart rate, without affecting myocardial contractility or repolarization significantly. - It does not cause the **ST segment changes** characteristic of digoxin effect or toxicity.

Q: A 10-year-old child with Valvular heart disease on heart failure treatment, has the following ECG tracing. What is the diagnosis?

Non paroxysmal atrial tachycardia with regular AV block. ***Non paroxysmal atrial tachycardia with regular AV block*** - The ECG shows a sustained atrial tachycardia with a **consistent P-P interval**, indicating a non-paroxysmal origin. - There is a **fixed ratio between P waves and QRS complexes** (e.g., 2:1 or 3:1), demonstrating a regular AV block, likely due to increased vagal tone or AV nodal dysfunction, often seen in cases of **digoxin toxicity** (given the patient is on heart failure treatment for valvular heart disease). *Tall tented T-wave* - **Tall, tented T-waves** are characteristic of **hyperkalemia**, but the ECG tracing does not exhibit this morphology. - While hyperkalemia can cause rhythm disturbances, the predominant feature here is a regular atrial tachycardia with AV block, not T-wave changes typical of electrolyte imbalance. *Ventricular bigeminy* - **Ventricular bigeminy** would manifest as alternating normal QRS complexes with premature ventricular contractions (PVCs). - The ECG shows a narrow complex tachycardia with visible P waves, which are not characteristic of PVCs or ventricular bigeminy. *Non paroxysmal atrial tachycardia with irregular AV block* - Although there is non-paroxysmal atrial tachycardia, the **AV block is regular** (e.g., a consistent 2:1 or 3:1 conduction ratio), not irregular. - An irregular AV block would suggest variability in AV nodal conduction, such as in AV Wenckebach or Mobitz type II with variable conduction, which is not what is seen in this tracing.

Q: A patient develops missed beats after thrombolysis for MI. ECG shows:

Mobitz I heart block. ***Mobitz I heart block*** - The ECG shows a **progressive lengthening of the PR interval** before a QRS complex is dropped (missed beat), which is characteristic of Mobitz type I (Wenckebach) heart block. - This type of block is often **benign** and located in the AV node, frequently resolving spontaneously, especially after thrombolysis for an inferior MI. *Mobitz II heart block* - Characterized by **sudden, unexpected dropped QRS complexes** without prior PR interval lengthening. - Mobitz II usually indicates a block below the AV node (infranodal) and is considered more serious, often requiring a pacemaker. *Complete heart block* - In complete (third-degree) heart block, there is **no conduction between the atria and ventricles**, meaning P waves and QRS complexes are completely dissociated. - The ventricular rhythm is typically slow and independent of the atrial rhythm, which is not seen here as some P waves conduct. *Sick sinus syndrome* - Sick sinus syndrome is a **dysfunction of the SA node**, leading to various arrhythmias such as sinus bradycardia, sinus arrest, or sinoatrial block. - While it can cause missed beats, the ECG pattern here specifically points to a problem with AV conduction (PR interval changes and dropped QRS), not primary sinus node dysfunction.

Q: Comment on the diagnosis.

Left bundle branch block. ***Left bundle branch block*** - The ECG shows **wide QRS complexes** (>0.12s), characteristic of a bundle branch block. - The **dominant S wave** in V1 and **broad, notched R wave** (or RR' pattern) in V5/V6, along with the absence of Q waves in lateral leads (I, V5, V6), indicate **left bundle branch block**. *Right bundle branch block* - This would typically present with a **dominant R wave** (RSR' pattern) in **V1** and a wide S wave in V6, which is not seen here. - The QRS complex would also be wide, but the morphology in V1 and V6 would be different. *Complete heart block* - This condition involves **AV dissociation**, where P waves and QRS complexes beat independently with no consistent relationship. - While QRS complexes might be wide if the escape rhythm is ventricular, the key feature of a complete heart block is **AV dissociation** which is not present in the given image. *Accelerated idioventricular rhythm* - This rhythm originates from the ventricles at a rate between 60-120 bpm, resulting in **wide QRS complexes** without preceding P waves. - However, the rhythm in the ECG appears to be sinus, preceding P waves are present before each QRS and the morphology is indicative of a conduction block rather than a ventricular escape rhythm.

Q: A 60-year-old patient is having recurrent syncopal attacks post myocardial infarction. The ECG shows:

Mobitz II heart block. ***Mobitz II heart block*** - The ECG demonstrates consistent **P-P intervals** with some P waves not followed by a QRS complex, indicating **intermittent dropped beats** without progressive PR prolongation. - This type of block is often associated with structural damage to the infranodal conduction system (below the AV node), which is especially concerning in a patient with a recent **myocardial infarction** and recurrent syncope. *Accelerated idioventricular rhythm* - This rhythm is characterized by a **wide QRS complex** at a rate between 60-100 bpm, typically with a gradual onset and termination, and usually does not cause syncope unless rapid or with underlying severe heart disease. - The ECG shows narrow QRS complexes interspersed with dropped beats, not a predominantly wide QRS rhythm originating from the ventricles. *Ventricular bigeminy* - This rhythm involves an alternating pattern of a **normal QRS complex followed by a premature ventricular contraction (PVC)**. - The ECG does not show alternating normal beats and PVCs; rather, it shows P waves without subsequent QRS complexes. *Wenckebach phenomenon* - Also known as Mobitz Type I AV block, it is characterized by **progressive lengthening of the PR interval** until a QRS complex is dropped. - In this ECG, there is no progressive PR interval lengthening; instead, P waves are suddenly blocked, which is characteristic of Mobitz II.

Q: Cannon A waves are seen in the JVP of a patient. ECG shows:

Third degree heart block. ***Third degree heart block*** - **Cannon A waves** in the JVP occur when the right atrium contracts against a closed tricuspid valve, which happens when atrial and ventricular contractions are **dissociated** as seen in **complete heart block**. - In the provided ECG, there is complete dissociation between P waves (atrial activity) and QRS complexes (ventricular activity), with P waves occurring regularly but independently of the QRS complexes, which signifies a **third-degree (complete) heart block**. *First degree heart block* - Characterized by a **prolonged PR interval** (>0.20 seconds) where every P wave is followed by a QRS complex. - There is no dissociation of P waves and QRS complexes, and therefore no cannon A waves due to atrial contraction against a closed tricuspid valve. *Second degree heart block* - Involves some P waves not being followed by a QRS complex, indicating **intermittent conduction failure**. - There can be Wenckebach (Mobitz I) or Mobitz II, both of which involve some degree of P-wave-QRS coupling, usually not leading to constant or prominent cannon A waves. *Mobitz II heart block* - Defined by intermittently **dropped QRS complexes** without progressive PR lengthening, often with a constant PR interval before the drop. - While some dropped beats occur, there is still a clear relationship between the P waves and the conducted QRS complexes, which differs from the continuous and complete AV dissociation seen with cannon A waves in third-degree block.

Question 1

The ECG shows a heart rate of 40 bpm, left axis deviation, and QRS duration >120 msec. There are deep monophasic S waves in V1-V3, broad monophasic R waves in lateral leads I, aVL, V5-V6, and absent Q waves in lateral leads with M shaped notch in peak of R wave in V5-V6. What is the diagnosis?

Accepted Answer

LBBB

Answer

RBBB

Answer

Left anterior fascicular block

Answer

Left posterior fascicular block

Question 2

A 30-year-old lady with scleroderma presents with progressive dyspnea on exertion. Which of the following is incorrect about the ECG finding?

Accepted Answer

Heart rate of 75 bpm

Answer

Right axis deviation

Answer

T wave inversion in V1-V3

Answer

rSR' pattern in V1

Question 3

What is the cardiac axis in the ECG provided?

Accepted Answer

Left axis deviation

Answer

Normal axis

Answer

Right axis deviation

Answer

Extreme axis deviation

Question 4

What is the axis in the ECG provided?

Accepted Answer

Left axis deviation

Answer

Normal

Answer

Right axis deviation

Answer

Extreme axis deviation

Question 5

A 50-year-old woman with rheumatic heart disease is on medication for heart disease. She feels unwell for most part of the day. Which of the following medicine is responsible for the ECG changes shown below? (Recent NEET Pattern 2016-17)

Accepted Answer

Digoxin

Answer

ACE inhibitor

Answer

Diuretics

Answer

Ivabradine

Question 6

A 10-year-old child with Valvular heart disease on heart failure treatment, has the following ECG tracing. What is the diagnosis?

Accepted Answer

Non paroxysmal atrial tachycardia with regular AV block

Answer

Tall tented T-wave

Answer

Ventricular bigeminy

Answer

Non paroxysmal atrial tachycardia with irregular AV block

Question 7

A patient develops missed beats after thrombolysis for MI. ECG shows:

Accepted Answer

Mobitz I heart block

Answer

Mobitz II heart block

Answer

Complete heart block

Answer

Sick sinus syndrome

Question 8

Comment on the diagnosis.

Accepted Answer

Left bundle branch block

Answer

Right bundle branch block

Answer

Complete heart block

Answer

Accelerated idioventricular rhythm

Question 9

A 60-year-old patient is having recurrent syncopal attacks post myocardial infarction. The ECG shows:

Accepted Answer

Mobitz II heart block

Answer

Accelerated idioventricular rhythm

Answer

Ventricular bigeminy

Answer

Wenckebach phenomenon

Question 10

Cannon A waves are seen in the JVP of a patient. ECG shows:

Accepted Answer

Third degree heart block

Answer

First degree heart block

Answer

Second degree heart block

Answer

Mobitz II heart block

Cardiology — MCQs

Cardiology — MCQs

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