If you are keen for your baby to be introduced to swimming before he is six weeks old your partner, or someone else, can take him. Some private baby swim classes start as early as four weeks but most classes at public pools begin at around 4 months.
Electrocardiogram (EKG, ECG) General Description. As the heart undergoes depolarization and repolarization, the electrical currents that are generated spread not only within the heart, but also throughout the body. This electrical activity generated by the heart can be measured by an array of electrodes placed on the body surface.
The time from the beginning of the P wave (atrial depolarization) to the beginning of the QRS complex (ventricular depolarization) is the PR interval. This represents the time that it takes for the electrical impulse generated in the sinus node to travel through the atria and across the AV node to the ventricles. The normal PR interval is 0.12 to 0.20 seconds or 120 to 200 milliseconds (ms). Multiple abnormalities of the PR interval can occur including prolongation (as depicted on the right), shortening of the PR interval and variation from beat to beat. These are discussed in detail in the ECG criteria review sections.