Johnson & Johnson (NYSE:JNJ) is buying medical device company Shockwave Medical (NASDAQ:SWAV) for 13.1billion.ShockwavemakesdevicesthatperformIntravascularLithotripsy.Theybreakupcalciumdepositsinarterieswithsoundwaves,inthesamewaykidneystoneshavebeentreatedfor30years.Theannouncementhadlimitedimpactonthestock,however.SWAVstockwassettoopenthismorningatabout325 per share, up just 1.6% from its April 4 close. JNJ stock was nearly unchanged at $153.Why No Big S ...