Too low blood pressure can cause people to be in shock. Systolic blood pressure below 10.7kPa (80mmHg) can be diagnosed as shock. Shock can manifest as unconsciousness, dizziness, pale, rapid heartbeat, and decreased urine output. If your husband can work normally, a blood pressure of 64/63mmHg may not be his real blood pressure. You should test your husband's blood pressure by different blood pressure monitors or ambulate blood pressure monitors. If your husband feels dizzy, palpitation, etc., he needs to go to the hospital immediately.