A silver lining has emerged to the story of one of the 41 labourers rescued from the Uttarkashi mountain tunnel after being trapped there for 16-and a-half traumatic days.

When the labourers were taken to AIIMS Rishikesh, Uttarakhand, after rescue on November 28 for health checkups, doctors found that Pushkar Singh Airi, 24, had a hole in the heart – a birth defect undiscovered till then.

Pushkar, a resident of Tanakpur in Champawat district, Uttarakhand, underwent heart surgery to correct the defect on December 28 and was discharged on Friday, the AIIMS revealed on Saturday.

In a statement, the AIIMS said that when Pushkar signed up for the job as tunnel excavation worker, he didn’t know he had ventricular septal defect — a hole in the wall separating the two ventricles, or lower chambers of the heart.

"Dr Varun Kumar, a cardiologist found during routine checkup of Pushkar that he had a hole in his heart since his birth but he didn't know this…. It was a complicated operation which became successful," the statement said.

"The specialist doctors of AIIMS conducted open heart surgery on Pushkar last week and he was released on Friday."

While the routine checkup — a consequence of the tunnel ordeal — turned out to be a blessing, Pushkar would have had to go without medical assistance had a health emergency occurred while he was trapped inside the collapsed tunnel.

The AIIMS said that "chief minister Pushkar Singh Dhami was taking updates in the case regularly" and that "he was operated under Atal Ayushman Health Scheme".

Dhami is an MLA from Champawat. Poor people get health insurance of Rs 5 lakh under the central government scheme.

"Pushkar wouldn’t have known about his disease if he were not admitted to AIIMS after being brought out of the tunnel," Dr Anshuman Darbari of the heart and lungs surgery department said.

"He was not prepared for surgery when he and the other 40 labourers were discharged from the hospital on December 1. He was admitted here again last week and the operation was done on December 28."

Pushkar didn't talk to reporters in his village. His father Ram Singh Airi said: "He is fine now and taking rest. The doctors told us he had this problem since birth, but we didn’t know about it."

Forty-one labourers were trapped in the Silkyara-Barkot tunnel on November 12 morning when a cave-in blocked the tunnel’s mouth with a 57-metre-thick barrier of debris.

A host of Indian and foreign experts and agencies, and imported auger machines, failed to dig through more than 45 metres of the debris because of metallic obstructions.

Finally, a group of rat-hole miners from New Delhi, experienced in digging through narrow tunnels and cleaning choked sewer lines, manually cleared the remaining 12 metres of debris and rescued the trapped workers on November 28 evening.