ECGs: Normal Sinus Rhythm, Sinus Tachycardia, Sinus Bradycardia - Practice Questions

A patient with sinus bradycardia (HR 38 bpm) is experiencing hypotension and dizziness. Which intervention should the nurse anticipate? A) Administer IV atropine B) Perform carotid massage C) Administer IV metoprolol D) Encourage a high-fiber diet

A) Administer IV atropine ✔ Atropine increases HR by blocking the vagus nerve. ✖ B is incorrect → Carotid massage further slows HR. ✖ C is incorrect → Metoprolol (beta blocker) would worsen bradycardia.

Which statement about sinus tachycardia is correct? A) It increases myocardial oxygen demand. B) It enhances coronary artery perfusion. C) It causes heart failure in all patients. D) It is never a normal response to stress.

A) It increases myocardial oxygen demand. ✔ Faster HR means the heart needs more oxygen but gets less perfusion. ✖ B is incorrect → Coronary perfusion decreases, not increases.

A nurse notes HR 120 bpm, normal P waves, PR interval 0.16 sec, and QRS duration 0.08 sec. What is the most likely rhythm? A) Sinus tachycardia B) Atrial fibrillation C) Ventricular tachycardia D) First-degree AV block

A) Sinus tachycardia ✔ HR >100 bpm, normal P waves, and a regular rhythm indicate sinus tachycardia.

Which of the following can cause sinus bradycardia? (Select All That Apply.) A) Beta blockers B) Carotid sinus massage C) Fever D) Hypothermia E) Valsalva maneuver

A, B, D, E ✔ Beta blockers, carotid massage, hypothermia, and vagal maneuvers lower HR. ✖ C is incorrect → Fever increases HR (tachycardia), not bradycardia.

A nurse is preparing to treat a patient with sinus tachycardia (HR 130 bpm, anxiety, BP 135/88 mmHg). Which intervention is most appropriate? A) Administer IV beta blockers B) Encourage deep breathing exercises C) Start transcutaneous pacing D) Administer IV atropine

B) Encourage deep breathing exercises ✔ If tachycardia is due to anxiety, relaxation techniques should be tried first.

An older adult patient is found to have HR 50 bpm but is asymptomatic. What should the nurse do? A) Administer IV atropine B) Prepare for transcutaneous pacing C) Continue to monitor the patient D) Administer epinephrine IV

C) Continue to monitor the patient ✔ If asymptomatic, no immediate treatment is needed.

A nurse is analyzing an ECG and notes the following: • Heart rate: 58 bpm • P waves present before each QRS complex • Regular rhythm • PR interval: 0.14 seconds • QRS duration: 0.08 seconds How should the nurse interpret this rhythm? A) Sinus tachycardia B) Normal sinus rhythm C) Sinus bradycardia D) Atrial fibrillation

C) Sinus bradycardia ✔ HR <60 bpm with a regular rhythm and normal P waves is sinus bradycardia. ✖ A is incorrect → Tachycardia is HR >100 bpm. ✖ B is incorrect → HR is below 60 bpm, making it bradycardia. ✖ D is incorrect → Atrial fibrillation has no P waves and is irregular.

Which symptom is most concerning in a patient with sinus bradycardia (HR 45 bpm)? A) Fatigue B) Blood pressure 110/70 mmHg C) Syncope D) Mild dizziness

C) Syncope ✔ Syncope (fainting) suggests decreased cardiac output and requires immediate intervention. ✖ A, B, and D are common but not as immediately concerning.

Which waveform represents ventricular repolarization? A) P wave B) QRS complex C) T wave D) PR segment

C) T wave ✔ The T wave represents ventricular repolarization (recovery phase).

A patient with sinus bradycardia (HR 38 bpm) is dizzy and hypotensive. What is the first-line treatment? A) IV atropine B) Carotid sinus massage C) Administer beta blockers D) Perform Valsalva maneuver

A) IV atropine ✔ Atropine increases HR by blocking the vagus nerve. ✖ B is incorrect → Carotid massage slows HR. ✖ C is incorrect → Beta blockers decrease HR. ✖ D is incorrect → Valsalva maneuver triggers vagal stimulation, further lowering HR.

What is the normal PR interval duration? A) 0.06-0.10 seconds B) 0.12-0.20 seconds C) 0.22-0.30 seconds D) 0.36-0.44 seconds

B) 0.12-0.20 seconds ✔ A prolonged PR interval (>0.20 sec) suggests first-degree AV block.

A patient has a PR interval of 0.24 seconds. What should the nurse document? A) Normal sinus rhythm B) Prolonged PR interval C) Shortened PR interval D) Widened QRS complex

B) Prolonged PR interval ✔ A normal PR interval is 0.12-0.20 sec. A PR >0.20 sec suggests a first-degree AV block.

The U wave may indicate?

Hypokalemia

What does the T wave represent?

Ventricular repolarization

What is the normal range for the QRS complex duration? A) 0.06-0.10 seconds B) 0.12-0.20 seconds C) 0.24-0.30 seconds D) 0.30-0.40 seconds

A) 0.06-0.10 seconds ✔ A widened QRS (>0.12 sec) suggests a bundle branch block.

A patient presents with symptomatic bradycardia (HR 40 bpm, syncope, and hypotension). Which intervention should the nurse anticipate? A) Administer IV atropine B) Perform carotid sinus massage C) Administer a beta blocker D) Encourage the patient to perform the Valsalva maneuver

A) Administer IV atropine Explanation: • Atropine blocks vagal stimulation, increasing HR, making it the first-line treatment for symptomatic bradycardia. • B is incorrect → Carotid sinus massage reduces HR further. • C is incorrect → Beta blockers lower HR, making bradycardia worse. • D is incorrect → The Valsalva maneuver worsens bradycardia.

A patient with sinus bradycardia (HR 42 bpm) has low urine output and altered mental status. What is the primary concern? A) Decreased cardiac output B) Myocardial infarction C) Atrial fibrillation D) Heart failure

A) Decreased cardiac output ✔ Bradycardia can reduce perfusion to vital organs, leading to confusion and low urine output. Final Notes: ✔ These questions are highly relevant for nursing student exams. ✔ They cover ECG recognition, nursing interventions, and key concepts needed for real-world practice.

A patient with symptomatic sinus bradycardia receives IV atropine. What is the expected outcome? A) Heart rate increases above 60 bpm B) Ventricular contractions slow down C) The P wave disappears from the ECG strip D) Blood pressure decreases

A) Heart rate increases above 60 bpm. Explanation: ✔ Atropine blocks the vagus nerve, increasing heart rate. ✖ B is incorrect → Ventricular contractions should not slow down. ✖ C is incorrect → P waves should remain visible. ✖ D is incorrect → BP should increase, not decrease.

A patient presents to the emergency department with HR 118 bpm, fatigue, weakness, low oxygen saturation, decreased urine output, and restlessness. The nurse suspects sinus tachycardia. What is the primary concern related to this condition? A) Increased oxygen demand of the heart B) Risk of sudden cardiac arrest C) Complete heart block development D) Formation of atrial clots

A) Increased oxygen demand of the heart Explanation: • Tachycardia decreases coronary perfusion time while increasing myocardial oxygen demand, leading to ischemia and further complications. • B is incorrect → Sinus tachycardia rarely leads to sudden cardiac arrest unless severe myocardial damage is present. • C is incorrect → Sinus tachycardia does not progress to heart block. • D is incorrect → Atrial clots are associated with atrial fibrillation, not sinus tachycardia.

A nurse is assessing a patient with sinus tachycardia. Which clinical findings are expected? (Select All That Apply.) A) Palpitations B) Hypotension C) Increased oxygen demand D) Cool, clammy skin E) Bradycardia

A, B, C, D ✔ Sinus tachycardia can cause palpitations, hypotension, increased oxygen demand, and cool skin due to reduced perfusion. ✖ E is incorrect → Bradycardia is the opposite of tachycardia.

A nurse is assessing a patient with sinus tachycardia (HR 125 bpm). Which findings are expected? (Select All That Apply.) A) Increased oxygen demand B) Low blood pressure C) Shortness of breath D) Cool, clammy skin E) Prolonged PR interval

A, B, C, D ✔ Tachycardia reduces cardiac filling time and increases oxygen demand. ✖ E is incorrect → PR interval is usually normal in sinus tachycardia.

Which of the following can cause sinus bradycardia? (Select All That Apply.) A) Hypoxia B) Beta blockers C) Pain D) Atropine E) Carotid sinus massage F) Valsalva maneuver

A, B, C, E, F Explanation: ✔ A) Hypoxia → Reduces oxygen supply, slowing HR. ✔ B) Beta blockers → Decrease sympathetic stimulation, leading to bradycardia. ✔ C) Pain → Can stimulate vagal response, slowing HR. ✔ E) Carotid sinus massage → Stimulates the vagus nerve, reducing HR. ✔ F) Valsalva maneuver → Increases vagal tone, slowing HR. ✖ D) Atropine → Increases HR, used to treat bradycardia.

Which symptoms are associated with symptomatic sinus bradycardia? (Select All That Apply.) A) Dizziness B) Chest pain C) Increased urine output D) Fatigue E) Syncope

A, B, D, E ✔ Decreased cardiac output leads to dizziness, fatigue, chest pain, and syncope. ✖ C is incorrect → Bradycardia reduces urine output due to low perfusion.

Which conditions or factors can lead to sinus bradycardia? (Select All That Apply.) A) Hypothermia B) Vagal stimulation C) Hyperthyroidism D) Beta blocker use E) Carotid sinus massage

A, B, D, E ✔ Hypothermia (A) slows the metabolic rate and HR. ✔ Vagal stimulation (B) (e.g., Valsalva maneuver) lowers HR. ✔ Beta blockers (D) reduce sympathetic activity, slowing HR. ✔ Carotid sinus massage (E) triggers a vagal response, reducing HR. ✖ C is incorrect → Hyperthyroidism increases HR, not decreases it.

Which medications can cause sinus bradycardia? (Select All That Apply.) A) Metoprolol B) Atropine C) Digoxin D) Verapamil E) Furosemide

A, C, D ✔ Beta blockers (metoprolol), digoxin, and calcium channel blockers (verapamil) slow HR. ✖ B is incorrect → Atropine increases HR. ✖ E is incorrect → Furosemide does not directly affect HR.

Which conditions or substances may cause sinus tachycardia? (Select All That Apply.) A) Fever B) Beta blockers C) Anxiety D) Hypovolemia E) Hyperthyroidism F) Calcium channel blockers

A, C, D, E Explanation: ✔ A) Fever → Increases metabolic demand, raising HR. ✔ C) Anxiety → Activates the sympathetic nervous system, increasing HR. ✔ D) Hypovolemia → The body compensates for low blood volume by increasing HR. ✔ E) Hyperthyroidism → Increases metabolism and cardiac output, leading to tachycardia. ✖ B) Beta blockers → Slow the heart rate. ✖ F) Calcium channel blockers → May cause bradycardia, not tachycardia.

Which factors can cause sinus tachycardia? (Select All That Apply.) A) Fever B) Beta blocker use C) Anemia D) Dehydration E) Hyperthyroidism

A, C, D, E ✔ Fever (A) → Increases metabolic demand, increasing HR. ✔ Anemia (C) → Less oxygen-carrying capacity, increasing HR to compensate. ✔ Dehydration (D) → Reduced blood volume, leading to compensatory tachycardia. ✔ Hyperthyroidism (E) → Increases metabolism and HR. ✖ B is incorrect → Beta blockers decrease HR and are used to treat tachycardia.

What is the normal duration of the QRS complex? A) 0.04-0.08 seconds B) 0.06-0.10 seconds C) 0.12-0.16 seconds D) 0.20-0.24 seconds

B) 0.06-0.10 seconds ✔ QRS represents ventricular depolarization. A normal duration is 0.06-0.10 sec. ✖ C and D are incorrect → A QRS >0.12 sec suggests conduction delays or bundle branch block.

Which patient with sinus bradycardia would most likely need a pacemaker? A) A 25-year-old athlete with HR 48 bpm and no symptoms B) A 60-year-old with HR 45 bpm and dizziness C) A 70-year-old with HR 55 bpm and occasional fatigue D) A 50-year-old with HR 50 bpm after taking a beta blocker

B) A 60-year-old with HR 45 bpm and dizziness. Explanation: ✔ Persistent symptomatic bradycardia (dizziness, syncope) requires a pacemaker. ✖ A is incorrect → Athletes can have lower HRs without symptoms. ✖ C is incorrect → Mild fatigue does not indicate pacemaker need. ✖ D is incorrect → Medication-related bradycardia may resolve by stopping the drug.

A patient's HR drops to 35 bpm with confusion and low BP. What is the priority nursing intervention? A) Start chest compressions B) Administer IV atropine C) Give a beta blocker D) Place patient in Trendelenburg position

B) Administer IV atropine ✔ Atropine increases HR by blocking the vagus nerve. ✖ A is incorrect → CPR is only needed if the patient has no pulse.

A patient with sinus tachycardia (HR 120 bpm) is being discharged. Which lifestyle modifications should the nurse recommend? A) Increase caffeine intake B) Avoid excessive alcohol and smoking C) Engage in strenuous exercise immediately after eating D) Sleep in a flat position to improve circulation

B) Avoid excessive alcohol and smoking ✔ Alcohol and smoking can trigger tachycardia and should be avoided. ✖ A is incorrect → Caffeine increases HR. ✖ C is incorrect → Exercise should be spaced out from meals to prevent reflux-related tachycardia. ✖ D is incorrect → Patients should elevate their head when sleeping.

A patient with sinus bradycardia (HR 42 bpm) is at risk for which complications? A) Increased cardiac output B) Decreased perfusion to vital organs C) Atrial fibrillation D) Ventricular fibrillation

B) Decreased perfusion to vital organs ✔ Bradycardia reduces cardiac output, causing hypotension, dizziness, and syncope.

A patient with HR 130 bpm, BP 110/70 mmHg, and anxiety is admitted. What is the nurse's priority action? A) Administer IV beta blockers immediately B) Encourage slow, deep breathing C) Perform carotid massage D) Prepare for electrical cardioversion

B) Encourage slow, deep breathing ✔ If tachycardia is due to anxiety, relaxation should be attempted first. ✖ A is incorrect → Medications should not be given before identifying the cause. ✖ C is incorrect → Carotid massage is not a first-line treatment. ✖ D is incorrect → Sinus tachycardia does not require cardioversion.

Which patient with sinus bradycardia is most likely to need a pacemaker? A) HR 55 bpm, no symptoms B) HR 40 bpm, frequent dizziness and syncope C) HR 50 bpm, occasional fatigue D) HR 48 bpm after taking a beta blocker

B) HR 40 bpm, frequent dizziness and syncope ✔ Symptomatic bradycardia requires pacemaker consideration.

Which characteristics define normal sinus rhythm (NSR)? A) HR 50-100 bpm, irregular rhythm, normal P waves B) HR 60-100 bpm, regular rhythm, P wave before each QRS C) HR >100 bpm, wide QRS complex D) HR <60 bpm, absent P waves

B) HR 60-100 bpm, regular rhythm, P wave before each QRS ✔ This describes NSR. ✖ A is incorrect → HR should be 60-100 bpm, and the rhythm must be regular. ✖ C is incorrect → HR >100 bpm suggests tachycardia. ✖ D is incorrect → NSR must have P waves present.

A patient with HR 40 bpm, dizziness, and syncope requires which treatment? A) IV beta blockers B) IV atropine C) Carotid sinus massage D) Adenosine

B) IV atropine ✔ Atropine increases HR by blocking vagal stimulation. ✖ A, C, D would further decrease HR.

A patient becomes unresponsive with sinus bradycardia (HR 30 bpm) and BP 75/40 mmHg. What is the priority nursing intervention? A) Administer IV atropine B) Initiate CPR C) Perform the Valsalva maneuver D) Administer a beta blocker

B) Initiate CPR ✔ If a patient is unresponsive with low HR and BP, start CPR immediately. Final Notes: ✔ This now completes over 65 high-yield nursing student exam questions! ✔ These questions help reinforce ECG analysis, nursing interventions, and real-world clinical decision-making.

A nurse observes an ECG with the following characteristics: • Heart rate: 85 bpm • P waves present and uniform • PR interval: 0.14 seconds • QRS duration: 0.08 seconds • Regular rhythm How should the nurse interpret this rhythm? A) Atrial fibrillation B) Normal sinus rhythm C) Sinus tachycardia D) Sinus bradycardia

B) Normal sinus rhythm ✔ NSR characteristics: HR 60-100 bpm, regular rhythm, normal P waves, PR interval 0.12-0.20 sec, and QRS 0.06-0.10 sec. ✖ A is incorrect → Atrial fibrillation has an irregular rhythm and no distinct P waves. ✖ C is incorrect → Sinus tachycardia is HR >100 bpm. ✖ D is incorrect → Sinus bradycardia is HR <60 bpm.

A patient with symptomatic bradycardia (HR 34 bpm, dizziness, BP 80/50 mmHg) is not responding to atropine. What is the next step? A) Administer IV epinephrine B) Prepare for transcutaneous pacing C) Give an additional beta blocker D) Have the patient perform Valsalva maneuver

B) Prepare for transcutaneous pacing ✔ If atropine fails, pacing is the next step for symptomatic bradycardia. ✖ A is incorrect → Epinephrine is not the first choice; pacing is preferred. ✖ C is incorrect → Beta blockers would worsen bradycardia. ✖ D is incorrect → Valsalva maneuver slows HR further.

A nurse observes the following ECG characteristics: • Heart rate: 50 bpm • P waves present before each QRS • PR interval: 0.16 seconds • QRS duration: 0.08 seconds What is the best interpretation of this ECG? A) Normal sinus rhythm B) Sinus bradycardia C) Atrial fibrillation D) Ventricular tachycardia

B) Sinus bradycardia Explanation: • Sinus bradycardia criteria: ✔ HR <60 bpm ✔ Regular rhythm ✔ P waves before each QRS ✔ PR interval 0.12-0.20 sec ✔ QRS duration 0.06-0.10 sec • A is incorrect → HR is below normal range (60-100 bpm). • C is incorrect → Atrial fibrillation has irregular rhythm and no P waves. • D is incorrect → Ventricular tachycardia has wide QRS complexes and HR >100 bpm.

Where should limb leads be placed when performing a 12-lead ECG? A) Upper arms and lower legs B) Wrists and ankles C) Shoulders and thighs D) Chest and back

B) Wrists and ankles ✔ Standard limb leads are placed on the wrists and ankles.

On ECG paper, how many small boxes equal 1 second? A) 5 B) 10 C) 25 D) 50

C) 25 ✔ Each small box = 0.04 sec; 25 small boxes = 1 second.

On an ECG strip, how many large boxes equal 6 seconds? A) 10 B) 15 C) 30 D) 60

C) 30 ✔ Each large box = 0.20 sec; 30 large boxes = 6 seconds.

On an ECG strip, how many large boxes equal one second? A) 1 B) 2 C) 5 D) 10

C) 5 ✔ Each large box = 0.20 seconds. Five large boxes = 1 second.

Where should lead V4 be placed? A) 4th intercostal space, right sternal border B) 4th intercostal space, left sternal border C) 5th intercostal space, left midclavicular line D) 5th intercostal space, left anterior axillary line

C) 5th intercostal space, left midclavicular line ✔ Lead V4 is positioned at the midclavicular line in the 5th intercostal space.

A 30-year-old marathon runner has an ECG showing HR 50 bpm, regular rhythm, normal P waves, and no symptoms. What should the nurse do? A) Give atropine to increase HR B) Prepare for emergency transcutaneous pacing C) Continue to monitor the patient D) Administer epinephrine IV

C) Continue to monitor the patient ✔ Athletes often have lower resting HRs due to improved cardiac efficiency.

Sinus tachycardia is often a compensatory mechanism in response to which condition? A) Hypertension B) Fluid overload C) Hypovolemia D) Hypoglycemia

C) Hypovolemia ✔ Low blood volume triggers tachycardia to maintain cardiac output.

Why does persistent sinus tachycardia place stress on the heart? A) It decreases oxygen consumption in the myocardium. B) It increases coronary perfusion time. C) It reduces coronary perfusion while increasing oxygen demand. D) It decreases ventricular contraction strength.

C) It reduces coronary perfusion while increasing oxygen demand. Explanation: ✔ Tachycardia reduces diastolic filling time, decreasing blood supply to the heart muscle while increasing oxygen needs. ✖ A is incorrect → Tachycardia increases oxygen consumption. ✖ B is incorrect → Coronary perfusion time decreases, not increases. ✖ D is incorrect → Contractility remains strong unless heart failure develops.

ST segment elevation on an ECG suggests: A) Ventricular hypertrophy B) Hyperkalemia C) Myocardial infarction D) Atrial fibrillation

C) Myocardial infarction ✔ ST elevation suggests acute myocardial injury.

A nurse is analyzing a patient's ECG strip and notes the following: • Heart rate: 72 bpm • Regular atrial and ventricular rhythm • P waves present and consistent, occurring before each QRS complex • PR interval: 0.14 seconds • QRS duration: 0.08 seconds Which interpretation is most accurate? A) Atrial fibrillation B) Sinus tachycardia C) Normal sinus rhythm D) Sinus bradycardia

C) Normal sinus rhythm Explanation: • Normal sinus rhythm includes: ✔ HR 60-100 bpm ✔ Regular rhythm ✔ P waves present, consistent, and occurring before each QRS ✔ PR interval: 0.12-0.20 seconds ✔ QRS duration: 0.06-0.10 seconds • A is incorrect → Atrial fibrillation has an irregular rhythm and no distinct P waves. • B is incorrect → Sinus tachycardia is HR >100 bpm. • D is incorrect → Sinus bradycardia is HR <60 bpm.

Which criteria are used to determine if a rhythm is normal sinus rhythm (NSR)? A) Irregular atrial and ventricular rhythms B) PR interval greater than 0.24 seconds C) One P wave for every QRS complex D) Heart rate between 50-90 bpm

C) One P wave for every QRS complex ✔ NSR characteristics: • Regular rhythm • HR 60-100 bpm • P waves present, uniform, and precede each QRS • PR interval 0.12-0.20 sec • QRS duration 0.06-0.10 sec ✖ A is incorrect → NSR is regular, not irregular. ✖ B is incorrect → A PR >0.20 sec suggests first-degree AV block. ✖ D is incorrect → HR should be 60-100 bpm.

A nurse reviewing an ECG notes a regular rhythm, HR 110 bpm, normal P waves, PR interval 0.14 seconds, and QRS duration 0.08 seconds. How should the nurse interpret this rhythm? A) Normal sinus rhythm B) Sinus bradycardia C) Sinus tachycardia D) Atrial fibrillation

C) Sinus tachycardia Explanation: ✔ HR >100 bpm with a regular rhythm and normal P, PR, and QRS complexes = sinus tachycardia.

A nurse is assessing a patient with sinus bradycardia (HR 48 bpm). Which symptom would require immediate intervention? A) Mild fatigue and dizziness B) Blood pressure 128/78 mmHg C) Syncope (fainting) D) Asymptomatic presentation

C) Syncope (fainting) Explanation: • Syncope indicates decreased cerebral perfusion due to low cardiac output, requiring immediate intervention. • A is incorrect → Mild fatigue and dizziness are common but not immediately life-threatening. • B is incorrect → A normal BP suggests compensatory mechanisms are working. • D is incorrect → Asymptomatic bradycardia does not require treatment.

A patient with sinus tachycardia (HR 120 bpm) reports anxiety, palpitations, and dizziness. What should the nurse do first? A) Administer IV beta blockers B) Have the patient perform vagal maneuvers C) Give oxygen at 4L via nasal cannula D) Determine the underlying cause

D) Determine the underlying cause. Explanation: ✔ Sinus tachycardia is a symptom, not a primary disorder. Identifying and treating the cause (pain, fever, dehydration, anxiety) is the priority. ✖ A is incorrect → Beta blockers should not be given before assessing the cause. ✖ B is incorrect → Vagal maneuvers are not the first step for sinus tachycardia. ✖ C is incorrect → Oxygen may be needed, but only if hypoxia is present.

What is the J point?

The transition from the QRS complex to the ST segment.

A prolonged QT interval increases the risk of which condition?

Torsades de Pointes.