Otterbein/Grant CRNA ECG II Quick Review

Magnesium sulfate is the pharmacologic treatment of choice for Torsades de Pointes, a life-threatening arrhythmia that is often associated with a prolonged QT interval. Magnesium helps to stabilize the electrical activity of the heart and can help normalize the QT interval. It is commonly administered intravenously in emergency situations to quickly restore normal heart rhythm and prevent further complications.

Patients with Wolff-Parkinson-White syndrome have an abnormal electrical pathway called the bundle of Kent that allows for premature activation of the right ventricle. This leads to the characteristic delta waves seen on an electrocardiogram. Administering drugs that enhance retrograde conduction, such as verapamil, diltiazem, and digoxin, can further worsen the condition by increasing the risk of rapid heart rates and potentially life-threatening arrhythmias. Therefore, it is true that patients with Wolff-Parkinson-White syndrome should not receive these drugs.

Automaticity is controlled in a sense by phase 4 (K+)

V1 and V6 are the preferred leads for differentiating between a left and right BBB because they provide the best view of the electrical activity in the heart from the anterior and posterior perspectives. Lead V1 is positioned on the right side of the sternum and provides a view of the heart's electrical activity from the right side. Lead V6 is positioned on the left side of the body, in line with the mid-axillary line, and provides a view of the heart's electrical activity from the left side. By comparing the electrical activity in these two leads, it is possible to identify the presence of a left or right bundle branch block.

P waves varying in size, shape, and direction throughout a rhythm strip is indicative of a wandering atrial pacemaker. This condition occurs when the pacemaker site in the atria shifts, causing the P waves to have different characteristics. It can be identified by the presence of at least three different P wave morphologies in a single rhythm strip. This is different from sinus arrhythmia, which is characterized by an irregular rhythm with a consistent P wave morphology. First-degree heart block and PVCs do not typically cause variations in P wave characteristics.

1st degree heart block is not considered a severe dysrhythmia because it is a relatively mild conduction abnormality. In 1st degree heart block, there is a delay in the conduction of electrical impulses from the atria to the ventricles, resulting in a prolonged PR interval on the ECG. Although it indicates an abnormality in the electrical conduction system of the heart, it is usually asymptomatic and does not typically require immediate intervention or pose a significant risk to the patient's life.

The statement is true because a left bundle branch block (LBBB) can cause changes in the ECG pattern that mimic those seen in an anterior myocardial infarction (MI). This can make it difficult to accurately diagnose an old anterior MI based solely on the ECG findings. LBBB can mask or obscure the typical ECG changes associated with an anterior MI, such as ST segment elevation or Q waves. Therefore, the presence of LBBB can make it challenging to differentiate between an old anterior MI and the changes caused by the LBBB itself.

A BBB is called complete when the QRS complex, which represents the electrical activity of the ventricles in the heart, lasts for a duration greater than or equal to 0.12 seconds. This prolonged duration indicates a delay or blockage in the electrical conduction system of the heart, specifically in the bundle branches. Therefore, a QRS duration of 0.12 seconds or longer is characteristic of a complete bundle branch block.

The ability to cause an adjoining cell to depolarize and the speed by which the adjoining cell is depolarized defines conduction. Conduction refers to the transmission of electrical impulses along nerve fibers or muscle fibers. In this context, it specifically refers to the transmission of depolarization from one cell to an adjacent cell. The speed at which this depolarization occurs is an important aspect of conduction, as it determines how quickly signals can be transmitted through the nervous system or muscle tissue.

Come from the same impulse

Require: Imbalance between conduction and refractoriness and a unidirectional block.