Infective endocarditis is most often caused by

In the normal electrocardiogram, the PR interval represents

The PR interval represents the time from the onset of atrial activation to the onset of ventricular activity. During this time, the electrical impulse travels through the atria, the atrioventricular (AV) node, and the bundle of His before entering the ventricles and initiating ventricular depolarization. Option A is incorrect because the atrial depolarization is represented by the P wave. Option B is incorrect because the ventricular depolarization is represented by the QRS complex. Option D is incorrect because there is no such term as “electrical systole” of the ventricles in ECG interpretation.

Chronic bronchitis is a type of chronic obstructive pulmonary disease (COPD) that is characterized by inflammation and narrowing of the bronchial tubes, which can lead to symptoms such as cough, shortness of breath, and wheezing. The primary cause of chronic bronchitis is smoking, and the most effective way to halt its progression is by quitting smoking.

Smoking cessation is the cornerstone of treatment for chronic bronchitis, as continued smoking can worsen inflammation in the airways and accelerate the progression of the disease. In addition to smoking cessation, other treatments may include bronchodilators (such as albuterol) to help open the airways and improve breathing, postural chest drainage techniques to help clear mucus from the lungs, and antibiotics to treat bacterial infections.

While these treatments can help manage symptoms and prevent complications, they are not as effective as smoking cessation in halting the progression of chronic bronchitis. Therefore, it is important for individuals with chronic bronchitis to quit smoking as soon as possible to slow the disease process and improve their overall health.