Scar formation , the accumulation of excess fibrous connective tissue ( the process called fibrosis ) , leads to thickening of the walls .
Scar formation , the accumulation of excess fibrous connective tissue ( the process called fibrosis ) , causes reduced oxygen supply in the blood .
Scar formation , the accumulation of excess fibrous connective tissue ( the process called fibrosis ) , leads to thickening of the walls , and causes reduced oxygen supply in the blood .