Vol.2-Ch.6 "PT Monitoring Tech" Flashcards
Describe the two main type of systems that operate the hear.
A mechanical system (valves, cardiac muscle, blood flow) and An electrical system (controls rhythm of contraction)
“It is a mechanical pump the runs on electricity”
The heart really has 2 pumps, a _____ and a _____ pump.
Right (A and V) and a left (A and V)
What is the hearts natural “pacemaker” and where is it located?
The Sinoatrial Node (SA Node) and it is located in the right atrium
How does the SA node create an electrical impulse?
Through depolarization; which occurs when the electrolytes Sodium and Potassium cross cell membranes and cause a shift in cell polarity
When a cardiac cell depolarizes is the inside of the cell more positive or negatively charged?
Positive
What is the bundle of His?
The atrioventricular (AV) fibers in the ventricles
What connects the SA Node to the AV Node?
Intraatrial pathways
What is the name of the system that spreads the electrical current in the heart from an inferior to superior direction across the myocardium?
The Purkinje system
What are the 3 types of ECG Leads?
- Bipolar
- Augmented
- Precordial
What is the name for the placement cites of the 3 pibolar leads (actually usually 4) and where does the name come from?
Einthoven’s Triangle, named after the creator of the ECG.
(There are usually 4 pads though, one placed on each limb, although the right leg is usually considered a ground or extra since the legs give virtually the same reading)
How fast does the ECG graph paper move?
25 mm/sec
What are the 4 ECG components and 2 time intervals?
- P Wave = Atrial Depolarization
- QRS complex = Ventricular Depolarization
- T Wave = Ventricular Repolarization
- U Wave = Occurs occasionally; they follow the T wave and usually indicate an abnormality
- PR interval = beginning of P to beginning of QRS
- ST segment = distance from S to T
What are the 3 bipolar lead placement sites?
Also, which is the most commonly used and why?
- Positive on left arm ; negative on right arm
- Positive on left leg ; negative on right arm
- positive on left leg ; negative on left arm
The second is the most common because it is usually sufficient at identifying life threatening arrhythmias.
If you suspect a mycardial infarction, is a single lead enough? If not what should be used?
No, a 12 lead is the best tool for identifying cardiac ischemia (not enough blood perfusion) or infarction.
What is an artifact?
Deflections on the ECG produced by other factors other than the heart’s electrical system such as: muscle tremors, shivering, pt moving, machine malfunction, or most likely and commonly loose leads.
What arteries deliver blood to the heart?
Right and Left Coronary Arteries (The left is bigger and has 2 parts)
What are the 3 zones of myocardial damage?
- Ischemia - Myocardium is oxygen deprived
- Injury - Myocardium is damaged from prolonged ischemia
- Infarction - Death of myocardial tissue
What is the main limitation of a 4 or 12 lead?
They do not give any info on the mechanical system of the heart (aka it doesn’t tell you if it is actually pumping or has anything to pump)
What do the 12 leads consist of?
3 bipolar leads 3 unipolar (augmented) leads 6 precordial (chest) leads
What are the 3 unipolar leads?
- aVR (pos on right arm ; neg on left arm and left leg)
- aVL (pos on left arm ; neg on right arm and left leg)
- aVF (pos on left foot ; neg on left and right arm)
What % of the oxygen usually binds to the hemoglobin molecule?
97%
Hemoglobin are made up of how many protein chains?
4, usually 2 alpha and 2 beta