Have you ever wondered what seasoned investors do during market downturns like the one we've been experiencing since the end of 2021? I can't speak for all of them, but buying more shares of my favorite growth stocks at a relative discount is at the top of my financial agenda.

From a purely emotional standpoint, buying into weakness feels like the wrong move. Sticking to successful businesses with strong competitive advantages, though, gives you a great chance of coming out ahead over the long run.

I bought shares of two of these three healthcare stocks last year, and all three are on my buy list for 2023. Despite impressive performances from their underlying businesses, these stocks are down by 42% to 65% from their respective peaks.

Inari Medical

Inari Medical (NARI 0.26%) develops and manufactures medical devices that you probably haven't heard of or even considered. ClotTriever is used to treat deep vein thrombosis, while FlowTriever handles smaller clots that jam up circulation in the lungs.

Inari's devices are basically catheters that cardiovascular surgeons use to mechanically remove venous blood clots. This is a huge improvement over the earlier standard of care. Traditionally, folks who go to the hospital with venous blood clots have been treated with powerful blood thinners.

Unfortunately, hospital-strength blood thinners can lead to fatal bleeding events if patients aren't monitored closely. Inari's devices can dramatically shorten patients' stays in intensive care units. In many cases, patients they are used on don't need to stay in an ICU at all.

Inari recently reported preliminary sales figures from 2022's fourth quarter, and its devices are flying off the shelves. Sales grew 29% year over year (at the midpoint of management's range). Expectations for 2023 suggest revenue will climb by between 23% and 25% this year. Given that there are no similar devices on the market competing with its products, Inari's growth could continue at a rapid pace for many years.

Shockwave Medical

Shares of Shockwave Medical (SWAV) are down around 39% from the peak they reached in 2022.

It's the only company that markets intravenous lithotripsy (IVL) devices approved to treat peripheral and coronary artery disease. These are essentially catheters that cardiovascular surgeons slide into arteries that have been hardened by calcium deposits.

Shockwave's IVL devices apply sonic pressure to break apart calcium deposits embedded inside an artery before an angioplasty balloon stretches that artery from the inside out. Hardened arteries don't always cooperate with angioplasty balloons, and softening the artery with IVL first makes the procedure much safer. Results of its Disrupt clinical trial showed that patients with peripheral artery disease were 77% less likely to experience a split-open artery when treated with Shockwave's IVL devices.

Compelling clinical trial data is driving strong sales growth. Preliminary figures suggest Shockwave's total sales more than doubled in 2022. Management's forecast for this year is that sales will increase by between 35% and 39%. The lack of any competitors capable of marketing similar IVL devices suggests that Shockwave shareholders could enjoy many more years of rapid growth.

InMode

InMode (INMD -1.39%) is also a medical device maker, but unlike Inari and Shockwave, its wares are not used in the cardiovascular realm. The company develops and markets minimally invasive devices that sculpt fat tissue and smooth out wrinkled skin.

Shares of InMode are around 65% below the high-water mark they set in late 2021. Now you can buy the stock for just 13.1 times forward earnings estimates. At this valuation, even if the company grows at a snail's pace, investors could accrue significant gains over the long run.

InMode's growth rate decelerated in 2022, but its third-quarter revenue still rose 29% year over year. Sales of services and consumable accessories (which need to be replaced for each procedure) jumped 53% year over year.

I'm buying this stock hand over fist right now because I think it can grow at a satisfactory pace in 2023 and for many years to come. In 2023, InMode expects total revenue to climb by around 16% to between $525 million and $530 million. This is a significant sum, but it's just a tiny sliver of its addressable market.

According to Grand View Research, the global market for cosmetic surgery and procedures was valued at $63.4 billion in 2021. And it's growing fast: The cosmetic surgery market is expected to increase at an annual rate of 9.6% through 2030. With proprietary technology to keep potential competitors at a distance, we can look forward to InMode steadily gaining an increasing share of this enormous space.