Lipp Vis Nursing ChaptLWBK1630_C02_p013-068

20  Chapter 2 • Cardiovascular Care

A Look at a Holter Monitor

Holter Monitoring (Ambulatory ECG Monitoring) Ambulatory ECG monitoring records the heart’s activity as the patient follows his normal routine. The patient wears a small electronic recorder connected to electrodes placed on his/her chest and keeps a diary of his activities and associated symptoms. This test can be worn from 24 to 48 hours and for as long as months to years offering the ability to monitor cardiac ECG data during normal routine activity, including any physical and psychological stresses.

Portable ECG recorder Patient event marker button ECG leadwires

Normal Conduction Intervals in Adults

However, the subclavian, internal jugular, or brachial vein may also be used. The heart’s usual conduction is recorded first. The catheter sends electrical signals to the heart to change the heart rate and initiate an arrhythmia. Various drugs are then tried to terminate the arrhythmia. Also, sometimes the cardiologist can induce an arrhythmia and then immediately treat it using radiofrequency ablation, a pacemaker, or an implantable cardioverter defibrillator (ICD). IMAGING TESTS Various imaging and radiographic tests are used to help visualize heart structures and blood vessels throughout the cardiovascular system. Although many of these tests are noninvasive and quick to perform, some require the insertion of a cardiac catheter, injection of a contrast medium, or nuclear medicine to further enhance the image. Cardiac Catheterization Cardiac catheterization (cardiac catheterization or heart catheterization) is an invasive procedure to examine how well the heart is working. A catheter is inserted into a large blood

Catheter

SA node

AV node

Bundle of His

PA interval

AH interval

HV interval

PA interval = conduction from sinatrial (SA) node to atrioventricular (AV) node = 20 to 40 msec AH interval = conduction from AV node to bundle of His = 4 to 150 msec HV interval = conduction from bundle of His to ventricles = 35 to 55 msec

ELECTROPHYSIOLOGY STUDIES Electrophysiology studies are used to help determine the cause of an arrhythmia and the best treatment

for it. A bipolar or tripolar electrode catheter is threaded into a vein, through the right atrium, and across the septal leaflet of the tricuspid valve. The femoral vein is the most common choice for the catheter insertion.