Although we don't believe in timing the market or panicking over market movements, we do like to keep an eye on big changes -- just in case they're material to our investing thesis.

What: Shares of Motley Fool Rule Breakers recommendation Volcano (Nasdaq: VOLC) surged as much as 10% in intraday trading, after exceeding analyst estimates for first-quarter financial results.

So what: Interestingly, the move up came despite lower full-year guidance. Management cited $5 million worth of revenue impact from the twin tsunamis that struck Japan in March in lowering Volcano's 2011 targets from a range of $347 million to $352 million in revenue and $0.22 to $0.24 in per-share earnings to $342 million to $347 million in revenue and $0.19 to $0.21 in per-share profit. The revised estimates remained within reach of the midpoint of Wall Street's own projections.

Now what: Not so for Q1 results, however. Demand for Volcano's cardiac-imaging technology surged as revenue improved by 22% to $80.9 million. Markedly higher gross margin -- up 560 basis points year over year -- transformed last year's $0.08-per-share loss into a $0.02-per-share profit. Analysts had been expecting $78.4 million and a $0.03-per-share loss. Even though Volcano trades for a significant premium to peers Boston Scientific (NYSE: BSX) and St. Jude Medical (NYSE: STJ), judging by these results, it's worth every penny.

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This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.