Electrical Activity and EKG
The Cardiac Action Potential Has a Prolonged Refractory Period
- Heart action potential has a prolonged spike (depolarized)
- Membrane is refractory for a long time
- This prevents summation and gives the heart time to fill
All Parts of the Heart Beat Spontaneously
- Heart muscle does not require stimulation by a nerve
- Nerves usually inhibit the heart beat; cutting the nerves -> heart speeds up
- Beat originates as a depolarization in the heart muscle cell itself (self stimulation)
- All parts of the heart can beat spontaneously
This is a normal rhythm, and is not of diagnostic significance unless the rate, which ranges from 60 to 100 beats per minute, is not appropriate for the clinical setting.
This rhythm differs from normal sinus rhythm only in that the rate is above 100 beats per minute. The differential diagnosis is extensive. Common causes are anxiety; physiological stress such as hemorrhage, dehydration, sepsis, and fever; and hyperthyroidism. Correction of the underlying cause, if necessary, is recommended.
This is a preview of Electrocardiographic Rhythms-Biomedical terminology of ECG. Read the full post (4224 words, 1 image, estimated 16:54 mins reading time)
Atrial fibrillation (AFib) is one of the prominent causes of stroke, and its risk increases with age. We need to detect AFib correctly as early as possible to avoid medical disaster because it is likely to proceed into a more serious form in short time. If we can make a portable AFib monitoring system, it will be helpful to many old people because we cannot predict when a patient will have a spasm of AFib.
This is a preview of Atrial fibrillation detection by heart rate variability in Poincare plot. Read the full post (361 words, 1 image, estimated 1:27 mins reading time)
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High blood pressure is a very common condition in modern society. It has been estimated that one in five Americans, around 50 million people, suffer from high blood pressure. In general more men than women have high blood pressure, and the number of sufferers of both genders increases rapidly with age.
In around 5% of cases of high blood pressure is caused by kidney problems, but the causes of the other 95% of cases are unknown. There are a number of factors such as race, age, obesity, stress, smoking and lack of exercise that can contribute to the likelihood of a person developing high blood pressure but usually no one cause is directly responsible.