<Tr> <Th> Parameter </Th> <Th> Normal value </Th> <Th> Value comments </Th> <Th> Clinical significance </Th> </Tr> <Tr> <Td> QRS duration </Td> <Td> 0.06--0.10 s </Td> <Td> Shorter in children and in tachycardia </Td> <Td> Prolonged duration indicates e.g. hyperkalemia . or bundle branch block </Td> </Tr> <Tr> <Td> QRS amplitude </Td> <Td> <Ul> <Li> S amplitude in V1 + R amplitude in V5 <3.5 millivolt (mV) </Li> <Li> R + S in a precordial lead <4.5 mV </Li> <Li> R in V5 or V6 <2.6 mV </Li> </Ul> </Td> <Td> </Td> <Td> Increased amplitude indicates cardiac hypertrophy </Td> </Tr> <Ul> <Li> S amplitude in V1 + R amplitude in V5 <3.5 millivolt (mV) </Li> <Li> R + S in a precordial lead <4.5 mV </Li> <Li> R in V5 or V6 <2.6 mV </Li> </Ul>

Which part of the ekg appears prior to the qrs complex