TEST 1 Flashcards
excitability
ability to respond to electrical stimulation
automaticity
ability of the cell that alone that can generate and create an electrical discharge
conductivity
ability of the pacemaker cells to transmit the electricity from one to the next
contractility
shortening and lengthening or the actual propelling of blood toward
normal Na+
3.5-5
polarization
cardiac cells at rest, no electrical activity
repolarization
return of the ions to a resting state, causing relaxation of cardiac muscle
what are the two functions of the heart
- generate and conduct electricity
- serve as a pump to push blood forward and throughout the body
Cardiac electrical activity is due to:
Na+
K+
Ca+
cardiac cells at rest, no electrical activity
polarization
return of the ions to a resting state, causing relaxation of cardiac muscle
repolarization
“action potential” or contraction
depolarization
name the steps of the release of an impulse
- generated by automaticity of cardiac cells
- begins depolarization
- ions move across membranes causing contraction of cardiac cells/muscle
- moves as wave through the heart
- repolarization=relaxation and building of energy to fire again
What is the normal conduction sequence
- SA
- AV
- Bundle of His
- Right and left bundles
- Purkinje Fibers
what is cardiac output
- amount of blood pumped out in a given time
- usually in L/min
- changes with metabolic need
- normal is 4-8L/min
Cardiac output = ??
cardiac output = stroke volume x heart rate
among of blood ejected from either ventricle with a single contraction
stroke volume
an increase in ____ alone can improve cardiac output but ___ has a greater effect
stroke volume
heart rate
the pressure in which ventricles fill, due to venous blood return
preload
determined by systemic resistance
afterload
what is a pacemaker
- an electronic device that delivers and electrical stimulus to the heart via leads
- leads are passed intravenously into the heart or stuttered directly to the epicardium(a serous membrane that forms the innermost layer of the pericardium and the other surface of the heart)
- provide artificial electrical stimuli to the heart muscle when the hearts intrinsic electrical system is malfunctioning
how does a pacemaker work?
- leads (insulated wires) sense intrinsic electrical activity of the heart
- generator provides electrical stimulus when necessary (pacing)
pacemaker education
- site care to avoid infection
- take pulse daily
- avoid emi
- s/s of pacemaker failure
- follow up
post op care instructions after pacemaker implantation
- do not raise arm on the side of the device above shoulder for three weeks
- no heavy lifting for three week (no heavier than a gallon of milk)
- allow stern-strips to fall off on their own
- avoid getting the incision wet for one week
contact local provider for what symptoms following a pacemaker implantation
- fever chills
- increased redness, pain, drainage, swelling or warmth at incision site
- twitching sensation in the chest_symptoms similar to what you experienced prior to the device insertion
- a single/jolt strong shock in the chest area
what are some recommendations for a pacemaker:
- keep small hand held appliances 6” from the device while in use
- use and store cell and cordless phones on the opposite side of the device
- keep device 12” from power tools or small running engines
- ground all power tools
- try to avoid chain saws
contractility:
force of contraction
preload:
degree of stretch
after load
systemic resistance
atrial kick
The contraction of the atrium, which accounts for 20-30% of cardiac output
in cardiac conduction name what the SA node does:
- electrical impulses are 60-100bpm
- it is the p wave on an ECG
what is the atrioventricular junction in relation to cardiac conduction:
- PR segman on ECG
- contraction known as atrial kick
what is the backup system for the cardiac conduction?
bundle of HIS
what is a normal measurement of the QRS segment?
0.04-0.12 seconds
what is the normal measurement for the PR interval?
0.12-0.2 seconds
what does the P wave stand for in an ECG segment?
atrial depolarization and contraction
what does the PR interval stand for in an ECG segment?
time of depolarization from atria to ventricles
what does the QRS stand for in an ECG segment?
ventricular depolarization and contraction
what does the ST segment stand for in an ECG segment?
early ventricular depolarization and depolarization (rest phase)
what does the T represent in an ECG segment?
ventricular repolarization
what does the U represent in an ECG segment?
late ventricular depolarization of PUrkionje fibers
name the rhythm interpretation steps:
- determina heart rate: atrial (p waves) and ventricle rates (QRS)
- determine heart rhythm, is it regular?
- analyze P waves
- measure PR interval (0.12-0.2)
- Measure QRS (0.04-0.12)
- identify rhythm
1 small box on a ECG strip indicates___
0.04 seconds
1 large box is ___ small boxes and indicates___
5 small boxes
0.2 seconds
30 large boxes indicate ____
6 seconds
each hashmark on an ECG strip indicates__
3 seconds
what is a normal sinus rhythm
- rate: 60-100bpm
- rhythm: regular
- P waves: sinus, precede each QRS
- RP interval: .12-.2 seconds
- QRS duration: .02-.12
- significance: normal
- tx: none
