The election of Republican Scott Brown to a U.S. Senate seat in Massachusetts Tuesday could give a short-term lift to the big-name medical device manufacturers at the top of the iShares Dow Jones US Medical Devices ETF ( IHI) roster. Top medical device firms like Medtronic ( MDT), Thermo Fisher Scientific ( TMO) and Stryker ( SYK) have been under pressure during this young presidency as a major overhaul of the health care industry took shape. As health care reform, once hallmarked by a government-backed public option, was increasingly slowed by the legislative process and mercurial public opinion, health care stocks rebounded. Subsector ETF offer investors the unique ability to compare and track narrow slices of the market. While many ETFs currently compete in the health care space, a quick analysis of the iShares line-up offers a revealing look into this sector's trends. The iShares Dow Jones US Medical Devices ETF ( IHI), iShares Dow Jones US Pharmaceuticals ETF ( IHE) and iShares Dow Jones US Healthcare Providers ETF ( IHF) all fell significantly in 2008 as President Obama's election loomed large and rebounded in 2009 as a massive health care overhaul seemed increasingly improbable. In 2008, IHI, IHE and IHF fell 36.79%, 14.91% and 43.46%, respectively. As a "public option" became less of a threat to health care providers in 2009, IHF rebounded more than 35%. IHI and IHE also improved 38.49% and 30.06% in 2009, respectively. Year to date, the controversy surrounding health care reform appears to have strengthened the stocks of top industry names. IHI, IHE and IHF are up 3.49%, 2.53% and 5.76% year to date respectively. While once-embattled health care providers like UnitedHealth Group ( UNH) and WellPoint ( WLP) are leading the pack, the companies that comprise IHI's portfolio could also get a jolt from the latest slow-down in health care reform.