Upper UTIs are infections of the kidneys. These are potentially life threatening, if bacteria move from the infected kidney into the blood. This condition is called sepsis. Sepsis can cause dangerously low blood pressures, shock, and death.
So whe you hold your breath, you stop getting oxygen in your lungs that go to your heart. The oxygen level in the blood drops, so your muscles need more oxygen, so the heart pumps faster. This is like running, your muscles need more oxygen so heart pumps faster
With the benefit of breathing pure oxygen first, the current Guinness World Record for holding your breath underwater is held by Ricardo Bahia of Brazil at a whopping 20 minutes 21 seconds! Most people in good health can hold their breath for approximately two minutes. Experts believe that even a little bit of practice can increase that amount of time quite a bit.