There are different types of rhythms that can cause the heart rate to be too fast or too slow.
Another class of drug to lower cholesterol is called bile acid sequestrants. These drugs remove bile acids from the body. Niacin and fibrates are other drug classes for improving cholesterol levels. Surgical options can also treat heart disease. Coronary angioplasty is performed over one million times each year on patients in the United States, according to the NIH. In this procedure, a balloon is threaded into the affected blood vessel and inflated, pushing the plaque blocking the artery to the sides of the vessel.
Sometimes, this procedure is accompanied by placement of a stent — a mesh tube designed to hold the blood vessel open. Despite all that is known about it, heart disease is the leading cause of death in both men and women in the United States, according to the CDC, claiming over , lives in — more than a quarter of all deaths. EKG waveforms are displayed on monitors or paper. These EKG tracings have important features which can be analyzed to reveal a normal or an abnormal rhythm a dysrrhythmia.
The P wave indicates atrial depolarization and it is normally an upward deflection in the EKG tracing. Next the QRS complex indicates ventricle repolarization.
It typically starts with a negative deflection, then a large positive movement and then a negative movement, the S wave. A T wave normally follows the QRS complex. It is typically a upwards waveform, indicating repolarization of the ventricles. You can uncheck any area that you have previously mastered.
By convention, lead I has the positive electrode on the left arm, and the negative electrode on the right arm, and therefore measures the potential difference between the two arms. In this and the other two limb leads, an electrode on the right leg serves as a reference electrode for recording purposes.
In the lead II configuration, the positive electrode is on the left leg and the negative electrode is on the right arm. Lead III has the positive electrode on the left leg and the negative electrode on the left arm. These three bipolar limb leads roughly form an equilateral triangle with the heart at the center that is called Einthoven's triangle in honor of Willem Einthoven who developed the electrocardiogram in Whether the limb leads are attached to the end of the limb wrists and ankles or at the origin of the limb shoulder or upper thigh makes no difference in the recording because the limb can simply be viewed as a long wire conductor originating from a point on the trunk of the body.
Maximal positive ECG deflection occurs in lead I when a wave of depolarization travels parallel to the axis between the right and left arms. If a wave of depolarization heads away from the left arm, the deflection is negative.
Also by these rules, a wave of repolarization moving away from the left arm is recorded as a positive deflection.
Similar statements can be made for leads II and III in which the positive electrode is located on the left leg. For example, a wave of depolarization traveling toward the left leg produces a positive deflection in both leads II and III because the positive electrode for both leads is on the left leg. A maximal positive deflection is recorded in lead II when the depolarization wave travels parallel to the axis between the right arm and left leg.
Similarly, a maximal positive deflection is obtained in lead III when the depolarization wave travels parallel to the axis between the left arm and left leg. If the three limbs of Einthoven's triangle assumed to be equilateral are broken apart, collapsed, and superimposed over the heart, then the positive electrode for lead I is said to be at zero degrees relative to the heart along the horizontal axis see figure at right.
There are several methods for determining heart rate. Our first method is simple. Count the number of QRS complexes over a 6 second interval. Multiply by 10 to determine heart rate. This method works well for both regular and irregular rhythms. In the first image, we can count 7 QRS complexes, so the heart rate is The second method uses small boxes. Count the number of small boxes for a typical R-R interval.
Divide this number into to determine heart rate. In the second image, the number of small boxes for the R-R interval is These are termed unipolar leads because there is a single positive electrode that is referenced against a combination of the other limb electrodes.
The positive electrodes for these augmented leads are located on the left arm aV L , the right arm aV R , and the left leg aV F. The ECG machine does the actual switching and rearranging of the electrode designations. The three augmented leads, along with the three standard bipolar limb leads , are depicted as shown to the right using the axial reference system.
It is very important to learn which lead is associated with each axis. The three augmented unipolar leads, coupled with the three bipolar leads, constitute the six limb leads of the ECG.
These leads record electrical activity along a single plane, termed the frontal plane relative to the heart. Using the axial reference system and these six leads, it is simple to define the direction of an electrical vector at any given instant in time. Rarely seen; considered an 'electrical no-man's land'. The p-wave represents depolarization of the atria. The p-wave is typically upright in most leads except for aVR; an unusual p-wave axis inverted in other leads can indicate an ectopic atrial pacemaker.
If the p wave is of unusually long duration, it may represent atrial enlargement. This interval reflects the time the electrical impulse takes to travel from the sinus node through the AV node. View by Category Toggle navigation. Products Sold on our sister site CrystalGraphics. Com, penyusun Umm Musab dengan sedikit perubahan Whether your application is business, how-to, education, medicine, school, church, sales, marketing, online training or just for fun, PowerShow.
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