Rating Newest Oldest. Best Answer: Generally from 6 ½ -7 weeks is the time when a heartbeat can be detected and viability can be assessed. A normal heartbeat at 6-7 weeks would be 90-110 beats per minute.The presence of an embryonic heartbeat is an assuring sign of the health of the pregnancy.Once a heartbeat is detected, the chance of the pregnancy continuing ranges from 70-90% dependent on what type of ultrasound is used.ating Newest Oldest. Best Answer: Generally from 6 ½ -7 weeks is the time when a heartbeat can be detected and viability can be assessed. A normal heartbeat at 6-7 weeks would be 90-110 beats per minute.