Artificial hearts, for example, can cause clots to form when blood hits their surface the girdle material and these clots can cause strokes and death.

Smoking is a major risk factor for heart attacks, strokes, chronic obstructive pulmonary disease (COPD) (including emphysema and chronic bronchitis), and cancer (particularly lung cancer, cancers of the larynx and mouth, and pancreatic cancer).

If we go down the small pathway a little bit farther, we're entering the era of nanomedicine, the ability to make devices super small to the point where we can design red blood cells or microrobots that will monitor our blood system or immune system, or even those that might clear out the clots from our arteries.