Medtronic Quarterly Net Up  CHICAGO (Reuters) - Medtronic Inc. &lt;A HREF="http://www.investor.reuters.com/FullQuote.aspx?ticker=MDT.N target=/stocks/quickinfo/fullquote"&gt;MDT.N&lt;/A&gt; on Wednesday  said its quarterly earnings rose on brisk demand for devices  that manage irregular heart beats and products used to treat  the spine.