Cardiac tamponade can occur due to: 1  Dissecting aortic aneurysm (thoracic) 2  End-stage lung cancer. 3  Heart attack (acute MI) 4  Heart surgery. 5  Pericarditis caused by bacterial or viral infections. 6  Wounds to the heart.
Bid vs. ask and why yields matter. With many investments, the concept of bid and ask applies to prices. The bid price is what a buyer is willing to pay for a security, while the ask price is what a seller is willing to accept for the same security. The difference between those two numbers is known as the bid-ask spread, and in general, the narrower that spread, the more liquid the market is.
As with bid and ask prices, the spread between bid and ask yields is wider when markets are illiquid and narrower when there is a lot of trading activity. Most investors are more familiar with trading in the stock market than in the bond market. The concept of bid and ask yields might sound complex in theory.