Rockets-Lakers conference semifinals to put small ball to test.

Like an emergency room doctor putting a crash cart to use, James Harden saved the Rockets’ playoff lives Wednesday night.

It matters not why or how they ended up lifeless, without a heartbeat toward the end of the first-round Game 7 matchup against the Oklahoma City Thunder.

An emergency medical specialist can’t be too concerned about whether the steady diet of bricks the Rockets threw up from beyond the 3-point line throughout the series was soaked in saturated fat.

Or if hereditary factors were at play. We are talking about Choke City with a coach who has never taken a team to the NBA Finals and a best player whose only trip there was when he was a reserve.

Thanks to Harden’s block of a Luguentz Dort 3-point attempt with 4 seconds remaining, the Rockets have a heartbeat and a fresh start in the second round against the Lakers. Nothing else matters.

Mike D’Antoni goes so far as to hint that measurement of how well a team plays isn’t particularly valuable in the playoffs. Just keep the heart beating, baby.

“Right now … it’s not about how good you play,” the Rockets coach said. “It’s how hard you play it out. How engaged you are. It’s more brains and heart and not talent.

“If you want to win a championship or win playoff games, you’ve gotta do it with your heart.”

That the Rockets lost three close games to OKC doesn’t outweigh the fact they won only one, because that one was the decisive Game 7.

Playoff losses and stats don’t carry over to the next round.

Next up: the Lakers, who present a wholly different set of challenges than the Thunder.

The Rockets do hope their defensive might will continue. They were the top-rated defense in the first round, but that came against the Thunder’s middle-of-the-pack offense, the lowest-rated of the eight Western Conference playoff teams.

The Lakers weren’t much better than the Thunder offensively during the regular season, and the Rockets believe even with Los Angeles’ size advantage, they can hold their own.

In the NBA, size matters. But the Rockets think small ball is their only path to success.

The Lakers challenge that as much as any team, with 6-10 power forward Anthony Davis and 7-0 center JaVale McGee in the starting lineup along with 6-9 point-everything LeBron James running the show.

D’Antoni refers to the Lakers, who are the No. 1 seed in the Western Conference, as “the biggest team, the best team.”

The question of whether the Lakers can keep up with the Rockets might determine the series. If Houston find the shooting touch it’s been missing, that is.

While the Rockets led the NBA in 3-pointers made at 15.6 per game, the Lakers hit just 11 a contest, which ranked 24th. In three matchups with the Lakers this season, the Rockets made 10 more 3-pointers per game, including a whopping 40-11 edge in two victories.

To repeat that, they will need Harden to pick it up.

Until he grabbed the defibrillator, Harden had an awful night in Game 7, with just 17 points on 4-of-15 shooting, including 1-of-9 on 3-pointers.

The 39-point night he had a few weeks ago against the Lakers (on 50 percent 3-point shooting and with 12 assists) is more along the lines of what the Rockets will need from him.

The Harden who had more turnovers than made 3-pointers in a 4-1 NBA Finals loss with the Thunder to LeBron’s Heat in 2012 has a similar beard to the one who stars for the Rockets, but there isn’t much comparison between the two as basketball players.

The Rockets’ Harden is the face of an organization driving for more than a decent showing against the big, bad Lakers, who enter the series as about a 6-1 favorite.

The Rockets talk about being able to win games in a variety of ways. This is not the time to test that.

Make shots, they can beat the Lakers. Miss as many as they did against the Thunder — Eric Gordon made just 25 percent from deep; Harden just 31.3 percent — they don’t stand a chance.

Don’t tell them that, though.

“Ugly, scrappy, whatever it takes,” Harden said. “Games aren’t going to be pretty, but we can win when they’re scrappy and ugly as well.”