Download Section 2: Assessment Tools and Diagnostic Testing

Section 2:
Assessment Tools and
Diagnostic Testing Scenarios
Scenario #9
My Heart is Racing
Scenario Anatomy & Physiology and Disease Background Information
The heart is auto rhythmic and has a self-firing pacemaker, the sinoatrial (SA) node in the right atrium. Although the endocrine system and the intrinsic innervation to the heart by the autonomic nervous system (ANS)
have the ability to change the heart rate (HR) and the velocity of conduction, the basic rhythm is accomplished
only through the electrical pacemaker and the conduction system of the heart. The nervous system operates
quickly (seconds to minutes) and the endocrine system operates slowly (minutes to days).
Specific cardiac muscle cells (myocytes) repeatedly create spontaneous action potentials (AP) that trigger contractions of the myocardium. These cells are called auto-rhythmic self-excitable conduction cells. The autorhythmic cells have two essential functions. The first is they act as a pacemaker, setting the normal sinus rhythm
(NSR) for the entire heart and secondly, they form the conduction system, which is the route for distributing the
pacemaker initiated impulses throughout the myocardium.
The auto rhythmic system of conduction consists of the following parts.
1. Sinoatrial (SA) Node: Situated in the right atrium, it is composed of conduction myofibrils, which are muscle
cells that act as nerve cells. The SA node is commonly known as the primary pacemaker of the heart, firing
at the rate of approximately sixty to one hundred beats per minute in the adult.
2. Atrioventricular (AV) Node: Composed of conduction myofibrils, these autorhythmic cells are located at the
junction of the four chambers of the heart. This node is the secondary pacemaker, firing at the rate of approximately forty to fifty beats per minute in the adult.
3. Atrioventricular (AV) Bundle: This bundle of conduction myofibrils is also known as the AV junction as well
as the bundle of His. It is an extension from the AV node and literally traverses from the AV node into the
interventricular septum, separating the two pumping chambers.
4. Right Bundle Branch (RBB): A bifurcation of conduction myofibrils, located at the interventricular septum.
The branch distributes the impulses from the AV Bundle to the right ventricle (RV).
5. Left Bundle Branch (LBB): A bifurcation of conduction myofibrils, located at the interventricular septum.
This branch distributes the impulses from the AV Bundle to the left ventricle (LV).
6. Purkinje System: A conduction myofibril extension of the RBB and LBB that pass action potentials (AP) to
the myocardium of both the RV and LV, causing contraction.
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The conduction system of the heart relies on the histological importance of the intercalated discs (ICD). These
ICDs enable the action potentials (AP) to be distributed away from the SA node, conducing APs across the individual cardiac myocytes via gap junctions, leading to contraction of the heart.
Atrial tachycardia occurs when the electrical impulses all originate from the sino-atrial node (SA) at a rate
between 101 and 150 beats per minute (BPM). Common causes of atrial tachycardia include: exercise, anxiety,
fever and stimulants such as caffeine, nicotine or amphetamines. Atrial tachycardia has the potential to evolve
into a life threatening arrhythmia.
Scenario Skills Information and Matrix
To identify and to confirm atrial tachycardia, one must obtain a tracing of the heart rate and rhythm. This information is obtained by getting an Electrocardiogram (EKG) Three Lead (Lead II) EKG.
A minimum of a 6-second EKG strip should be initially obtained. The test should be conducted as per the
manufacturer’s instructions for the specific machine.
When looking at a rhythm strip, one should consider five components in the strip. These are the rhythm, rate,
shape of the P wave, PR interval, and the length of the QRS duration and its configuration.
Copyright @ 2015 Mark X VanCura, LLC. All rights reserved.
In atrial tachycardia because the impulse follows the normal conduction pathway, an upright P wave occurs before every QRS complex. The PR intervals remain with the established normal range of 0.12 to 0.20 second, and
the QRS complexes are less than 0.12 second. The EKG is symmetric, with all the P waves looking the same and
all QRS complexes are the same size and shape. As the rate of atrial tachycardia increases, the P waves become
hidden in the T wave of the preceding QRS complex, causing an irregular appearance of the T wave. There is a
regular rhythm since the P to P intervals and the R to R intervals are regular and equal in length.
The scenario has a focus on specific skills. However, there is the opportunity to develop many associated skills
during the session. The instructor will provide the guidance for additional skills that should be demonstrated.
Review those additional Student Healthcare Provider Skill Guides and Student Skill Instructional Videos as
directed.
Refer to the Essential Skills Scenarios Skill Matrix for details.
Scenario Primary Skill
Required and Additional Skill Guides
Student Skill Instructional
Guides
Videos
Cardiac (Heart) Rhythm
Interpretation
Electrocardiogram (EKG):
Performing a Three Lead
(Lead II) EKG
Required Skills
Hand Hygiene
Level of Consciousness
Medical Record Documentation
Basic Patient History
Patient Identification
Personal Protective Equipment
Professional Presentation
Vital Signs: Blood Pressure, Pain Score, Pulse,
Pulse Oximetry, Respiratory Rate, Temperature
My Heart is Racing
Blood Pressure
Breath Sounds Auscultation
Capillary Refill
EKG Lead II
Pulses
Additional Skills
Breath (Lung) Sounds Auscultation
Breathing (Respiratory) Assessment
Capillary Refill
Electrocardiogram (EKG): Performing a
Twelve Lead EKG
Heart Sounds
Intravenous (IV) Access-Peripheral in an Upper Extremity
Intravenous (IV) Therapy Fluid Administration
Medication Administration
Oxygen Administration
Skin Assessment
Venipuncture (Phlebotomy) Procedure
Copyright @ 2015 Mark X VanCura, LLC. All rights reserved.