Philadelphia Phillies ace right-hander Zack Wheeler was diagnosed with venous thoracic outlet syndrome and has been recommended to undergo season-ending decompression surgery in the coming weeks, the team announced Saturday.

The timeline for recovery following that surgery is six-to-eight months.

Per the Mayo Clinic, venous thoracic outlet syndrome occurs when one or more of the veins under the collarbone are compressed and damaged. This can result in blood clots.

With Wheeler sidelined, the National League East-leading Phillies will rely on left-handers Cristopher Sanchez, Jesus Luzardo and Ranger Suarez along with right-handers Aaron Nola and Taijuan Walker in their starting rotation.

Wheeler, 35, underwent the initial surgery to remove a blood clot in his right upper extremity on Monday.

He was placed on the 15-day injured list last Saturday due to a blood clot located near his right shoulder. He previously missed another start and was subtracted from the rotation one day after he allowed two runs on four hits over five innings in Friday's 6-2 win over the Washington Nationals.

Wheeler was an All-Star each of the past two seasons. In six seasons with the Phillies, the right-hander is 69-37 with a 2.91 ERA and 1,094 strikeouts to 220 walks in 979 innings.

In 24 starts this season, he is 10-5 with a 2.71 ERA and a National League-leading 195 strikeouts.

Before arriving in Philadelphia, Wheeler spent five seasons with the New York Mets.