Category: Fundamentals
Sinus tachycardia can be seen with any sympathetic excess, whether endogenous (pain, fever, hyperthyroidism) or exogenous (stimulants, drugs). The approach to the patient with sinus tachycardia centers on identifying and addressing the cause(s).
Cateogry: Fundamentals
At other times, sinus tachycardia is a counterproductive response, as in acute decompensated heart failure or aortic stenosis, in which a decrease in filling time further compromises cardiac output.
Category: Fundamentals
Sinus tachycardia is often a response to physiologic stress or is a compensation for a relative lack of perfusion or oxygen delivery (to increase cardiac output). Usually, the effect is salutary, as seen with hypovolemia, anemia or hypoxemia.
Category: Fundamentals
Sinus tachycardia displays a regular, usually narrow-complex tachycardia, with normal P waves preceding each QRS complex on the ECG. In adults, sinus tachycardia rarely exceeds a rate of 170 beats/min.
Category: Fundamentals
Direct therapy for PVCs toward correcting any precipitating condition whether it is catecholamine excess, drug effect, electrolyte imbalance, or cardiac ischemia. Often, PVCs do not require treatment in the ED.
Category: Fundamentals
Premature ventricular contractions (PVCs) occur in a wide variety of states. Occasional PVCs are common in healthy adults or conditions associated with catecholamine excess (anxiety, stimulants - caffeine, cocaine, amphetamines).
Category: Fundamentals
Premature atrial contractions (PACs) are common and usually have little clinical significance. PACs are abnormal P waves early in a cardiac cycle. Sometimes, the P wave may be difficult to detect if it is buried within the preceding T wave.
Category: Fundamentals
The hallmark of third-degree AV block, also known as complete heart block, is AV dissociation (no electrocardiographic relationship between P waves and QRS complexes), with an R-R interval longer than the P-P interval.
Category: Fundamentals
Type II second-degree AV block is a conduction block just below the level of the AV node. On the ECG, conduction of atrial impulses is sporadic and typically periodic, but the PR interval does not widen from beat to beat.
Category: Fundamentals
Type I second-degree AV block, is associated with progressive impairment of conduction within the AV node. The ECG shows a lengthening of the PR interval from beat to beat until a P wave is entirely blocked (so-called dropped beat).
Category: Fundamentals
First-degree AV block is from prolonged conduction at the level of the atria, AV node (most common), or His-Purkinje system. On the ECG, first-degree AV block shows a prolonged PR interval (> 0.20 second).
Category: Fundamentals
AV block results from impaired conduction through the atria, AV node or proximal His-Purkinje system. First- and second-degree AV blocks represent partial impairment, whereas third-degree block indicates complete interruption.
Category: Fundamentals
Sick sinus syndrome is a group of dysrhythmias caused by disease of the sinus node and its surrounding tissues, creating sinus bradycardia, sinus arrest or SA exit block. Long-term management requires permanent pacemaker placement.
Category: Fundamentals
Sinus dysrhythmia is a display of variation in heart rate that occurs during the respiratory cycle, manifested as normally conducted P waves with a variable P-P interval. It is a normal variant and is seen frequently in children and young adults.
Category: Fundamentals
Sinus bradycardia is often asymptomatic and requires no specific treatment. If needed, first-line treatment for symptomatic sinus bradycardia in adults is atropine, a 0.5 mg IV bolus, repeated as needed every 3-5 minutes, to a total dose of 3 mg.
Category: Fundamentals
Sinus bradycardia is characterized by a P wave with normal morphology, a fixed P-P interval equal to the R-R interval, and a ventricular rate below 60 beats/min. This pattern may be found in healthy individuals.
Category: Fundamentals
Bradycardia is defined as a ventricular rate of less than 60 beats/min, although in practice rates above 50 beats/min are not usually a concern. Bradycardia occurs because of depression of the sinus node or because of a conduction system block.
