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”). Continue reading →
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. Continue reading →
A 19-year-old white male presents to the emergency department (ED) in Connecticut after an episode of shortness of breath and syncope while at home. He reports having experienced recurrent episodes of palpitations and fatigue in the week before presentation. Yesterday, the patient sought medical attention for these symptoms at his pediatrician’s office. An electrocardiogram (ECG) was performed, but it was normal; the patient was sent home wearing a Holter monitor (also known as an ambulatory electrocardiography device). Today, while mowing the lawn, the patient again felt a sudden onset of palpitations, accompanied by shortness of breath and light-headedness. He went inside the house, where he suddenly “passed out” (according to the patient’s girlfriend). The girlfriend also states that he was unresponsive for a couple of minutes and that the patient exhibited no seizurelike activity or incontinence. She noted that he was “pretty much himself” once he regained consciousness. He was then brought by ambulance to the ED; a rhythm strip was acquired en route (see top image). Prophylactic transcutaneous pacer pads were placed by the emergency medical services (EMS) team. Continue reading →
The greatest change in ACLS is a reduced emphasis on additional modalities, such as medications, rhythm checks, and central line placement, that interrupt compressions for more than 10 seconds and an increased emphasis on searching for and correcting any cause for SCA.