1. Cardiac Cycle ► The two atria contract at the same time, then they relax while the two ventricles simultaneously contract. ► The contraction phase of the ventricle chambers is called systole. ► The relaxation phase is called diastole. ► At a normal heart rate, one cardiac cycle last for 0.8 seconds!

2. The electrocardiogram (EKG or ECG) is a graphic display of the electrical events of the cardiac cycle. Electrocardiogram? Each event has a distinctive waveform, the study of which can lead to greater insight into a patient’s cardiac output.

3. Wave Interpretation ► P Wave = contraction of atria ► PQ Wave = signal arrives at AV node slowing down a bit to allow ventricles to fill with blood ► Q Wave = signal moves to Bundle of His and divides into the bundles and Purkinje fibers ► R Wave = contraction of left ventricle ► S Wave = contraction of right ventricle ► T Wave = ventricles relaxing

5. Rule of 300 ► Take the number of “big boxes” between neighboring QRS complexes, and divide this into 300. The result will be approximately equal to the heart rate ► Although fast, this method only works for regular rhythms. (300 / 6) = 50 bpm

6. What is the heart rate? (300 / 1.5) = 200 bpm

7. 10 Second Rule ► As most EKGs record 10 seconds of rhythm per page, one can simply count the number of beats present on the EKG and multiply by 6 to get the number of beats per 60 seconds. ► This method works well for irregular rhythms.

8. What is the heart rate? 33 x 6 = 198 bpm

9. Pulse “Heart Rate” ► Pulse  Pressure wave of blood ► Monitored at “pressure points” in arteries where pulse is easily found ► Pulse averages 70–80 beats per minute at rest

10. Blood Pressure ► Measurements by health professionals are made on the pressure in large arteries  Systolic—pressure at the peak of ventricular contraction  Diastolic—pressure when ventricles relax  Write systolic pressure first and diastolic last (120/80 mm Hg) ► Pressure in blood vessels decreases as distance from the heart increases

11. Measuring Arterial Blood Pressure