EKG Lab

In class, we were instructed to perform a lab that deals with the human EKG(electrocardiogram). We hooked up electrode tabs onto our arms(2 each arm, one bicep and one on the forearm) and monitored our heart beats. I will show you mine, and describe what an EKG measures exactly.

As you can see, fairly normal heartbeat, and regular beat intervals. Now, I will show you another picture I found on the internet that will actually label and describe what each wave in an EKG is called.

As you all can see, each wave has its own label, even the flat parts are noticed as segments. I will break each part down and define them so you get a better idea of what each name is specifying. 

Feature	Description	Duration
RR interval	The interval between an R wave and the next R wave: Normal resting heart rate is between 60 and 100 bpm.	0.6 to 1.2s
P wave	During normal atrial depolarization, the main electrical vector is directed from the SA node towards the AV node, and spreads from the right atrium to the left atrium. This turns into the P wave on the ECG.	80ms
PR interval	The PR interval is measured from the beginning of the P wave to the beginning of the QRS complex. The PR interval reflects the time the electrical impulse takes to travel from the sinus node through the AV node and entering the ventricles. The PR interval is, therefore, a good estimate of AV node function.	120 to 200ms
PR segment	The PR segment connects the P wave and the QRS complex. The impulse vector is from the AV node to the bundle of His to the bundle branches and then to the Purkinje fibers. This electrical activity does not produce a contraction directly and is merely traveling down towards the ventricles, and this shows up flat on the ECG. The PR interval is more clinically relevant.	50 to 120ms
QRS complex	The QRS complex reflects the rapid depolarization of the right and left ventricles. They have a large muscle mass compared to the atria, so the QRS complex usually has a much larger amplitude than the P-wave.	80 to 120ms
J-point	The point at which the QRS complex finishes and the ST segment begins, it is used to measure the degree of ST elevation or depression present.	N/A
ST segment	The ST segment connects the QRS complex and the T wave. The ST segment represents the period when the ventricles are depolarized. It is isoelectric.	80 to 120ms
T wave	The T wave represents the repolarization (or recovery) of the ventricles. The interval from the beginning of the QRS complex to the apex of the T wave is referred to as the absolute refractory period. The last half of the T wave is referred to as the relative refractory period (or vulnerable period).	160ms
ST interval	The ST interval is measured from the J point to the end of the T wave.	320ms
QT interval	The QT interval is measured from the beginning of the QRS complex to the end of the T wave. A prolonged QT interval is a risk factor for ventricular tachyarrhythmias and sudden death. It varies with heart rate and for clinical relevance requires a correction for this, giving the QTc.	Up to 420ms in heart rate of 60 bpm
U wave	The U wave is hypothesized to be caused by the repolarization of the interventricular septum. They normally have a low amplitude, and even more often completely absent. They always follow the T wave and also follow the same direction in amplitude. If they are too prominent, suspect hypokalemia, hypercalcemia or hyperthyroidism usually.[28]
J wave	The J wave, elevated J-point or Osborn wave appears as a late delta wave following the QRS or as a small secondary R wave. It is considered pathognomonic of hypothermia or hypocalcemia.[29]

I added a graph that was already made so I wouldn't have to type it myself, but these are all correct facts about the EKG. I will label the internet site after if you care to learn more about the names of the waves, intervals, or segments. Remember, not everybody will have the same EKG reading, in fact, nobody probably will. The same  EKG reading would be as rare as finding the same DNA shared with somebody, if not even more rare! If you look above on the graph it labels how long each interval lasts. As you can see in the EKG labeled picture, the PR segment is the segment that is the shortest, lasting only half a second at most! Think about it, how many people are going to have the same heartbeat rhythm, especially when it is measured as precise as milliseconds? Thank you for taking the time to read my blog, I hope it was somewhat useful to all of you that follow my blogs!

Sites Used

http://en.wikipedia.org/wiki/Electrocardiography

http://www.webmd.com/heart-disease/electrocardiogram