Pulmonary (or pulmonic) insufficiency (or incompetence, or regurgitation) is a condition in which the pulmonary valve is incompetent and allows backflow from the pulmonary artery to the right ventricle of the heart during diastole. While a small amount of backflow may occur ordinarily, it is usually only shown on an echocardiogram and is harmless. More pronounced regurgitation that is noticed through a routine physical examination is a medical sign of disease and warrants further investigation. If it is secondary to pulmonary hypertension it is referred to as a Graham Steell murmur. Signs and symptoms
Because pulmonic regurgitation is the result of other factors in the body, any noticeable symptoms are ultimately caused by an underlying medical condition rather than the regurgitation itself. However, more severe regurgitation may contribute to right ventricular enlargement by dilation, and in later stages, right heart failure. A diastolic decrescendo murmur can sometimes be identified,( heard best) over the left lower sternal border. Causes
Among the causes of pulmonary insufficiency are:

Pathophysiology
The pathophysiology is due to diastolic pressure variations between the pulmonary artery and right ventricle, differences are often very small, but increase regurgitation. An elevation in pulmonary insufficiency due to elevated intrathoracic pressure is relevant in ventilated patients (having acute restrictive right ventricular physiology). The reasons for changes in stiffness of the right ventricles walls are  not well understood, but such stiffness is thought to increase with hypertrophy of the ventricle.
Timolol is a non-selective beta-adrenergic antagonist. Comparison to other products
Despite each of the active ingredients being availed in their own respective formulations, combination formulations are typically more convenient for the patient without sacrificing any quality in therapy. In the case of Cosopt, the combination formulation dosed twice daily provides equivalent treatment to both dorzolamide 2% dosed two times daily and timolol 0.5% dosed three times daily. Specifically, the mean reduction in intraocular pressure was 27.4% for the combination product, 15.5% for dorzolamide 2%, and 22.2% for timolol 0.5%. Compared to other products such as latanoprost, both are equally efficacious with regard to lowering intraocular pressure and getting patients to reach their target intraocular pressure. Cosopt, though, is typically less well tolerated than other treatments due to a well documented feeling of ocular burning upon administration. History
Cosopt gained Food and Drug Administration (FDA) approval in April 1998 and was supplied initially by Merck. In 2016, Merck & Co. had $95.3 billion in total assets, $40.3 billion in total equity, $24.3 billion in long term debt, and $13.4 billion in working capital. This same year Merck & Co spent $20 billion total split virtually evenly between research and development (R&D) and marketing efforts. Cosopt had annual sales of $342 million during the 12 months before June 2008.