Reading 2: 83-99 Flashcards
What is experiment 2-1?
ECG and peripheral circulation
What do you do in the ECG n peripheral circulation exp?
Record single lead ECG and pulse wave in finger simultaneously
What is the purpose of exp 2-1
- Measure and correlate the ECG and the pulse in a resting individual
- Demonstrate time delay that occurs btwn electrical events in heart and mechanical events in circulatory system
What is the device used to measure pulses of blood?
PT-104 plethysmograph
What are the steps in the Exp 2-1: the ECG and peripheral circulation?
- Set up ECG Cable and Pulse Transducer into iWorx
- Remove all jewelry on subject’s wrists, ankles or clavicle
- Clean area with no hair on wrists and ankles or clavicle and abdomen with alcohol
- Attach red lead to left wrist/clavicle. Attach black lead to right wrist/clavicle. Attach green lead to right leg/abdomen
- Place plethysmograph on volar surface (fingerprints) of distal segment of middle finger/thumb. Wrap velcro around end of finger to attach unit.
- Subject needs to sit quietly with hands in lap
- Turn on IXTA
- Open Labscribe -> click Settings -> Human Heart -> ECG-Circulation
- RECORD
- AUTOSCALE
- Type in subjects name Resting ECG/Pulse in MARK box
- STOP
- Save file as Grp#DayTimeLab2Ex1
- Find section of data with 10 exemplary ECG/pulse cycles in succession
What is the beat period and how to find it? Units?
- time interval btwn 2 adjacent R waves
- place one cursor on peak of one R wave and 2nd cursor on peak of adjacent R wave. Value for T2-T1 on ECG channel is the beat period
- units: seconds/beat
What is the R-R interval and how to find it?
- Time interval btwn peak of R wave and peak of pulse wave that follows the R wave.
- one cursor on peak of R wave n second cursor on peak of pulse wave to its right. Value of T2-T1 is this interval
What is the eqn to calculate HR using the beat period?
HR (bpm) = (60 seconds/minute) / (# seconds/beat)
What is exp 2-2?
Exercise, ECG, and peripheral circulation
The arterial system fxns as a ____ resevoir
pressure
What does signals from the autonomic NS do
Control tone of smooth muscle sphincters around arterioles… thus controlling distribution of blood flow to various organs
How is the distribution of BF influenced by local conditions
e.g. if cells require arterial blood, due to decline in pH or O2 lvls or inc CO2, smooth muscle sphincters open to let BF into those capillary beds
How does BF change w/exercise compared to rest
- flow to gut dec w/exercise
- flow to working skeletal muscles inc w/exercise
- inc CO -> inc amount of BF around circulatory system by several fold
What is the purpose of Exp 2: The ECG and Pulse After Leg exercises?
To measure n correlate ECG and pulse immediately after exercise using leg muscles
Steps of Exp 2?
- Same setup as in Exercise
- SETTINGS -> HUMAN HEART -> EXERCISE-ECG-CIRCULATION
- Disconnect snap leads n pulse plethysmograph from subject
- Subject exercise ~3 min at 70%max (150bpm) thru biking or treadmill or rowing
- After 3 mins have subject relax next to recording equipment
- Reconnect cables/leads n pulse plethysmograph
- RECORD -> AUTOSCALE ALL -> type ECG/Pulse-recovery into mark box
- Record for 2 mins, marking every 30 mins
- Stop and save
How to measure R wave amplitude
- one cursor on Q wave that precedes R wave and 2nd cursor on peak of R wave. Value for V2-V1 on ECG channel is amplitude
How to measure P-R interval
- one cursor on p wave 2nd cursor on beginning of QRS complex . Value for T2-T1 on ECG channel is P-R interval
How to measure Q-T interval
one cursor at beginning of QRS complex and 2nd at end of T wave. Value for T2-T1 on ECG channel is Q-T interval
How to measure T-P interval
One cursor at end of T wave n 2nd at beginning of P wave. Value of T2-T1 on ECG is T-P interval
What is and how to measure R-Pulse interval
- time interval btwn peak of R wave and peak of pulse wave that follows R wave
- one cursor on peak of R wave and 2nd on peak of pulse to its right. Value for T2-T1 on any channel is this interval
How to measure pulse wave amplitude
one cursor on baseline that precedes the pulse wave n 2nd cursor on peak of pulse wave. Value for V1-V2 on pulse channel is amplitude.
How does ability of stress influence risk of coronary heart disease
People who r unable to cope w/stressful events run 7x higher risk to suffer from CHD
How do those who can’t handle stress act during stressful situations
impatient, aggressive, dissatisfied, irritable
What is HRV (heart rate variability) and used for?
analysis of variability of R-R interval in ECG indicates imbalance btwn sympathetic n vagal influences on heart
- comparison of sympathetic and vagal activity used as measure of stress
How can HRV be studied
- mathematical modeling of HR regulatory systems
- Non linear methods for determining indices for regulatory fxns
- time domain methods to determine deviation of successive N-N (normal R-R) intervals
- Spectral domain methods to determine the power spectral density of definitive frequency components of the ECG
What is ULP
Power density # for ultra low frequency range (<0.003 Hz), and its prognosis of sudden cardiac death taken from 24 hr ECG recording highly accurate
what is VLP
Power density # for very low frequency range (0.003-0.04 Hz), and thought to be connected to thermoregulation, the renin-angiotensin system, and changes in PA
what is LP
Power density # for low frequency range (<0.04-0.15 Hz) that is generated mainly by sympathetic activity.
- Baroreceptor (pressure) modulation major component of LP power
what is HP
Power density # for high frequency range (0.15-0.40 Hz), and is derived from VAGAL activity which is modulated by RESPIRATION
What does LP and HP mainly represent respectively and their ratio mean
LP = sympathetic activity; HP = vagal activity. Their ratio (HRV ratio) good indicator of sympathetic-vagal balance
- ratio used to assess balance of ANS in various diseases
How does LP and HP change w/stress
Stress accompanied w/inc power spectral density (PSD) of LP (sympathetic) and dec PSD of HP (vagal activity)
What does a HRV ratio of 0.83 indicated
Vagal activity has greater influence on HR than symapthetic system
What is the usual HRV of young people
high as 1.5
What is happening in HRV exp
- PSA of HRV of subject determined from their ECG
- mathematical transformation of ECG to yield its power spectrum n analysis of spectrum determine density of defined frequency ranges in spectrum
- 1st step in analysis is to express successive R-R intervals as fxn of time/heartbeat #
- 2nd step convert result of 1st step (tachogram) to HRV power spectrum using Fast Fourier
- 3rd step determine PSD of certain frequency ranges in HRV power spectrum
What does the magnitude of the PSD in certain frequency indicate
Relative amt of activity in specific parts of ANS and lvl of stress in subject
HRV ratio of 6.9 indicates
sympathetic activity has greater influence on HR than vagal activity
Systolic and diastolic for high BP?
Systolic >139, diastolic >89
LP and HP of person with hypertension
Higher LP and lower HP value than non hypertensive persons
What is a frequent complication of diabetes and what can it result
neuropathy can result in fxnal autonomic denervation causing patients to develop fast, fixed HR. causes diabetics to have lower RR variance and smaller R-R interval. power spectrum look NORMAL at REST but DIMINISHED INC IN LP AND DIMINISHED DEC IN HP when STANDING/TITLED
What does smoking act synergistically with
- hypertension, oral contraceptives to inc risk of heart attack
LP and HP values of smokers?
Higher LP and lower HP values than non smokers; HRV ratios greater than 1.5
Steps in exp 3
- recording subjects resting ECG for 10 minute period
