He also began working with a colleague in a dog laboratory to devise a valvulotomy (surgical treatment for diseased heart valves).

He may have chosen to go to Charleston in part because the father of a high school classmate had once been the chief surgeon and residency program director at Roper Hospital.

He also worked in an animal laboratory at the medical school, using dogs to learn more about valve function and possible repair.

[2] By 1946, Smithy had devised what he called a valvulotome, an instrument he used to cut away scar tissue from the aortic valve.

[2] An Associated Press science editor heard Smithy's talk at the 1947 ACS conference and the possible breakthrough was widely published in newspapers.

Tuberculosis killed the most people under 50 in the 1940s, but because of the prevalence of rheumatic fever, narrowing of the mitral valve was the next most common cause of death in this age group.

Smithy's first patient, a 21-year-old woman named Betty Lee Woolridge, had sustained heart valve damage from rheumatic fever at the age of ten.

[2] It appears that Smithy declined Woolridge's initial request for surgical help, but she sent a second letter, asking him why he would continue to experiment on animals when he had a willing human patient.

When she arrived, Woolridge weighed 85 pounds, could not breathe while lying flat, and appeared so frail that Smithy nearly refused to operate on her.

He began corresponding with famed cardiac surgeon Alfred Blalock of Johns Hopkins Hospital, who he thought he could convince to perform the novel procedure.

[10] John Boone, chief of medicine at the Medical College of South Carolina, wrote to Blalock on Smithy's behalf in May 1948.

Blalock wrote back within days, asking Smithy to arrange a trip to Johns Hopkins where they could locate a patient and operate together.

The events have been described with slight variations, but it seems that the patient developed a fatal arrhythmia while being anesthetized or while the chest incision was being made.

[12] In early October 1948, Smithy developed pneumonia and was admitted to Roper Hospital; his condition was further compromised by cardiac asthma and another bout of rheumatic fever.

In any case, a conference presentation was given by Stallworth and a paper on the surgical treatment of valvular disease was later published in Surgery, Obstetrics & Gynecology.

[9] Smithy was posthumously named an "outstanding young man of 1948" by the South Carolina chapter of the Junior Chamber of Commerce.

However, Smithy's intracardiac injection of novocaine significantly decreased the likelihood of arrhythmias that could occur when the heart was surgically manipulated.

A Medical University of South Carolina library exhibit says that "[b]etter operations than Smithy's were already accomplished, and their value would become apparent.

In going the wrong way, Smithy nonetheless achieved positive results and invited comparisons that eventually led to the realization that commissurotomy was the operation of choice... his work, well publicized at the time, encouraged patients and physicians and prompted the concept that operative treatment of valvular heart disease could be successful.

The money built up over time, and after a local surgeon added to the fund, the university created the Horace G. Smithy Chair of Cardiothoracic Surgery in 1997.