hey suman follow this link for ur first question, this is not the complete answer though(
Entrez PubMed)
for second question:
Acute left heart failure may be triggered by a major event such as myocardial infarction in a previously healthy heart, or a relatively minor event such as the onset of atrial fibrillation in a diseased heart. An increase in the left ventricular diastolic pressure causes the pressure in the left atrium, pulmonary veins and pulmonary capillaries to rise. When the hydrostatic pressure of the pulmonary capillaries exceeds the oncotic pressure of plasma (about 25-30 mmHg) fluid moves from the capillaries into alveoli. This stimulates respiration, through a series of autonomic reflexes, producing rapid, shallow respiration. Congestion of the bronchial mucosa may cause wheeze (cardiac asthma).
but u keep searching for more. i hope u do, and post it in the same thread.