Arrhythmias

Question 1

Describe the EKG features of a normal sinus rhythm.

Answer 1

Sinus Rhythm

• PR interval (resistance to conduction at the AV node)
• QRS complex (ventricular depolarization)
• T wave (ventricular repolarization)
• Normal sinus rate: 60-100 bpm
• Normal PR interval is 0.12-0.20 seconds.

Question 2

Define Sinus Tachycardia

Answer 2

HR > 100bpm

*Beta-blocker is usually effective here

Question 3

Define sinus bradycardia

Answer 3

HR < 60bpm

• Atropine effective treatment here, if pt becomes v/v

Can cause syncope, lightheadedness or fatigue in elderly patients with age-related dysfunction→sick sinus syndrome

Question 4

What is a junctional (nodal) rhythm?

Answer 4

Region surrounding the AV node is often termed the “junction” and rhythms originating there are called junctional rhythms

• Regular rhythm w/ narrow QRS complexes
• P waves not seen because they are buried w/in QRS complex
• Often inverted because they are conducted upward from the AV node rather than downward from the SA node.

Question 5

What are the EKG features of a normal junctional (nodal) rhythm?

Answer 5

Regular, narrow (normal) QRS complex with no antecedent P waves.

Question 6

What are the ECG features of 1st degree A-V Block?

Answer 6

PR interval prolonged, increased junctional delay

• Causes: drug-induced (beta-blockers, some calcium blockers, digitalis), conduction system disease.
• EKG features: PR interval is greater than 0.2 seconds (one large block on the EKG).
• This is a benign condition that can proceed to more serious types of block.

Question 7

What are the ECG features of second degree A-V heart block?

Answer 7

Some P waves conduct and some do not

• Causes: conduction system disease, high vagal tone, excessive effects of drugs.
• EKG features: Some P waves conduct normally to ventricles but others do not. Patterns vary.
• If the rate is too slow to slow to support cardiac output adequately, syncope or confusion may occur requiring a pacemaker.

Question 8

What are the ECG features of third degree A-V block?

Answer 8

Both Ps and QRSs show regular rhythm, but they are at different rates.

• Causes: av node or junctional failure with aging, infarct or disruption during cardiac surgery—rarely caused by drugs.
• EKG features: Both Ps and QRSs show regular rhythm, but they are at different rates. With P rate > QRS rate.
• May cause syncope or sudden death. Usually requires a pacemaker.

Question 9

A-Fib

• What are the ECG features, causes, clinical manifestations, and treatment?

Answer 9

• EKG features: irregularly irregular ventricular rhythm. No p waves.
• Causes: NI subjects, aging, post-operative, heart disease, hyperthyroidism
• Clinical manifestations: rapid heart rate (syncope, ischemia, heart failure), loss of atrial kick (heart failure), atrial thrombi (embolic stroke).
• Treatment: anticoagulation, rate control with drugs, cardioversion—electrical or drugs, ablation.

Question 10

Atrial Flutter

What are the ECG features, causes, clinical manifestations, and treatment?

Answer 10

• EKG features: P waves (flutter waves) at rate of 240-320 bpm. Pulse may be regular or irregular. Ventricular rates vary widely—typically rapid if untreated.
• Complications: atrial flutter has some risk of embolic stroke due to clot in the left atrium, and may result in rapid ventricular rates that are poorly tolerated.
• Treatment: anticoagulation, rate control with drugs, cardioversion, ablation.

Question 11

Atrial Tachycardia

What are the ECG features, causes, clinical manifestations, and treatment?

Answer 11

• EKG features: harrow QRS complex, P waves present, but abnormal. Heart rate may be as high as 180.
• Causes: abnormal re-entry pathway.
• Clinical manifestations: rapid heart rate, very uncomfortable and disturbing.
• Treatment: Adenosine; ablation if recurrent problem.

Question 12

Premature atrial contraction

What are the ECG features, causes, clinical manifestations, and treatment?

Answer 12

• EKG features: premature beat, preceded by abnormal P wave, narrow QRS complex.
• Clinical manifestations: single-beat palpitation, most commonly noticed at rest, when low heart rates permit occurrence of premature ‘skipped beats’ and when distractions are reduced allowing awareness.
• Treatment: none. Beta-blockers if really annoying.

Question 13

Premature Ventricular Contraction (PVC)

What are the ECG features, causes, clinical manifestations, and treatment?

Answer 13

• EKG features: wide-abnormal QRS, No P-wave.
• Causes: random single, reentry arrhythmia—short path-length blocks re-entry.
• Clinical manifestations: single-beat palpitation, most commonly noticed at rest, when low heart rates permit occurrence of premature ‘skipped beats’ and when distractions are reduced allowing awareness.
• Treatment: none, beta-blockers if really annoying.

Question 14

Ventricular Tachycardia

What are the ECG features, causes, clinical manifestations, and treatment?

Answer 14

• EKG features: repetitive wide-abnormal QRS complexes, no p-wave
• Causes: fibrosis, infiltrate, dilation, long path length permitting reentry.
• Clinical manifestations: very bad. Abnormal ventricular contraction
• Treatment: emergency defibrillation.

Question 15

V-Fib

What are the ECG features, causes, clinical manifestations, and treatment?

Answer 15

• EKG features: abnormal, abnormal, abnormal—all noise, no p waves, no QRS complexes, no T waves.
• Causes: can progress from ventricular tachycardia. Heart failure.
• Clinical manifestations: very bad. No ventricular contraction.
• Treatment: immediate emergency defibrillation.