Quantcast Size and Time Intervals of EKG Waves. - Cardiac Impairment

Share on Google+Share on FacebookShare on LinkedInShare on TwitterShare on DiggShare on Stumble Upon
Custom Search
 
  
 
d. Size and Time Intervals of EKG Waves. The size of the deflection waves
and particular time intervals are important when you are reading an electrocardiogram.
For example, the duration of a normal "P" wave is between 0.06 and 0.1 seconds, the
time it takes for depolarization current to pass through the atrial musculature. An
increased width of "P" wave may indicate left atrial abnormality or right atrial
hypertrophy (enlargement). The deflection of a normal "P" wave is small due to the thin
walled structure of the atria. A "P" wave is usually no more than 3 mm high. A taller "P"
wave may indicate that atrial enlargement has occurred due to hypertension, coronary
pulmonade, or congenital heart disease.
(1)  P-R interval. Measured from the beginning of the P wave to the
beginning of the R wave, this wave pattern represents the conduction time from the
beginning of atrial excitation to the beginning of ventricular excitation. This is the time it
takes for an electrical impulse to travel through the atria and atrioventricular node to the
remaining conducting tissues. A medical condition that disrupts this electrical impulse
will display itself as a P-R interval that is longer than 0.2 seconds, due to the increased
time it takes to travel the conducting tissues. The normal P-R interval is between 0.12
and 0.20 seconds.
(2)  Q wave. The Q wave is defined as the first down (negative) deflection
following the P wave but coming before the R wave.
(3)  QRS complex. This complex is made up of three waves: the Q, the R,
and the S waves. The QRS complex represents ventricular depolarization. A normal
QRS measurement is less than 0.12 seconds. The QRS complex is larger than the P
wave on an EKG because ventricular depolarization involves a greater muscle mass
than atrial depolarization.
(4)
R wave. The R wave is the first upward (positive) deflection that follows
the wave.
(5)  S-T segment. Beginning at the end of the S wave ending at the
beginning of the T wave, this wave represents the time between the end of the spread
of the heart's electrical impulse through the ventricles and repolarization of the
ventricles. When a patient has acute myocardial infarction, the S-T segment is
elevated. When the heart muscle does not receive enough oxygen, the S-T segment is
depressed.
(6)  T wave. Representing repolarization of the ventricular cells, the T wave
is flat when the heart muscle does not receive enough oxygen; for example, in
atherosclerotic heart disease. When the body's potassium level is increased, the T
wave may be elevated. This wave occurs after the QRS complex.
NOTE:
Refer to figure 2-6 to see these waves.
MD0571
2-9



Medical News
Tweet of the Week: Candy Anatomy
(MedPage Today) -- Here's what happens when a med student...
medpagetoday.com
Someone Wants All That FitBit Data
(MedPage Today) -- Dietitians would be glad to evaluate data...
medpagetoday.com
Teamwork Cuts In-Hospital Observation Time
(MedPage Today) -- Lengths of stay cut substantially at one...
medpagetoday.com
New approaches for early diagnosis of Alzheimer's
Mild cognitive impairment, or MCI, may be one of Alzheimer's...
medicalxpress.com
Endovascular Clot Removal Wins Again (CME/CE)
(MedPage Today) -- Reduced disability with thrombectomy in REVASCAT trial....
medpagetoday.com
Doc Facebook, Avoiding Burnout: Healthcare Career Insights
(MedPage Today) -- Must-reads about the latest news and trends...
medpagetoday.com
Scope wins award for its “creative and effective approach” to promoting academic medicine
We’re happy to announce that Scope is a 2015 GIA...
scopeblog.stanford.edu
Kids with ADHD must squirm to learn, study says
For decades, frustrated parents and teachers have barked at fidgety...
medicalxpress.com
Hospital Leader: An Interview With Toronto's Adina Weinerman, MD
(MedPage Today) -- What strategies can streamline code status documentation?...
medpagetoday.com
Friday Feedback: What's Next for Medicare?
(MedPage Today) -- SGR has been repealed, but what does...
medpagetoday.com
USDA confirms bird flu at 5th South Dakota turkey farm
Five commercial turkey farms in South Dakota have now been...
medicalxpress.com
Glaxo recalls flu vaccine due to potency problem
GlaxoSmithKline is recalling remaining doses of a popular four-in-one flu...
medicalxpress.com
From beef tongue to beef on weck, menus tell culinary story
Before beef on weck and chicken wings became staples of...
medicalxpress.com
Cohen's Brain Bits: Dream On
(MedPage Today) -- REM sleep behaviors offer opportunity for early...
medpagetoday.com
Artificial blood vessel lets researchers better assess clot removal devices
Researchers at the University of California, San Diego School of...
medicalxpress.com
Mortality Equal With Simultaneous vs. Staged Hip Replacement (CME/CE)
(MedPage Today) -- Survival similar after 30 and 90 days,...
medpagetoday.com
Sugar Suppresses Body's Stress Response (CME/CE)
(MedPage Today) -- But soothing effect could have damaging long-term...
medpagetoday.com
Remembering the strange vigils of war through poetry and dance
In his Civil War-era poem, “Vigil Strange I Kept on...
scopeblog.stanford.edu
Review explores challenges of ocular antioxidants for cataracts
(HealthDay)—Delivery of antioxidants to the eye may be a therapeutic...
medicalxpress.com
Firm Claims Biotin Drug Improves Function in Progressive MS
(MedPage Today) -- One-year study meets primary disability-based endpoint, company...
medpagetoday.com
 


Privacy Statement - Copyright Information. - Contact Us

comments powered by Disqus

Integrated Publishing, Inc.
9438 US Hwy 19N #311 Port Richey, FL 34668

Phone For Parts Inquiries: (727) 755-3260
Google +