Studying the Basic ECG

INTRODUCTION

Normal sinus rhythm (NSR) is the characteristic rhythm of the healthy human heart. NSR is considered to be present if the heart rate is in the normal range, the P waves are normal on the ECG, and the rate does not vary significantly. If, however, the R-R interval is variable, the rhythm is called sinus arrhythmia. A sinus rhythm faster than the normal range is called a sinus tachycardia (see “Sinus tachycardia”), while a slower rate is called a sinus bradycardia (see “Sinus bradycardia”).

What is an AV Block? (Pediatric ACLS)

First-degree AV block:

In this condition, there is a delay of the electrical impulse reaching the lower chambers of the heart. It is not a complete heart block, merely a delay in conduction producing prolongation of the PR interval on the surface electrocardiogram. First-degree AV block is rare but may be seen in young, healthy adults, especially well-trained athletes owing to an increase in vagal tone. Patients are generally asymptomatic. In pediatrics it may be seen with certain types of congenital heart defects, after heart surgery or closure of an atrial septal defect, following catheter ablation, muscular dystrophy, rheumatic fever, lupus, rheumatoid arthritis, Lyme disease, tuberculosis, endocarditis, diphtheria, medications, coronary disease, heart failure and degenerative diseases of the electrical conduction system.