<P> When blood pressure is stated for medical purposes, it is usually written with the systolic and diastolic pressures separated by a slash, for example, 120 / 80 mmHg . This clinical notation is not a mathematical figure for a fraction or ratio, nor a display of a numerator over a denominator . Rather it is a medical notation showing the two clinically significant pressures involved (i.e., systolic - slash - diastolic, or 120 / 80). It is often shown followed by a third number, the value of the heart rate (in beats per minute), which typically is measured jointly with blood pressure readings . </P> <P> Examining diastolic function during a cardiac stress test is a good way to test for heart failure with preserved ejection fraction . </P> <P> Classification of Blood Pressure in Adults </P> <Table> <Tr> <Th> Blood Pressure Classification </Th> <Th> Systolic BP (mmHg) </Th> <Th> Diastolic BP (mmHg) </Th> </Tr> <Tr> <Td> Optimal </Td> <Td> <120 </Td> <Td> and <80 </Td> </Tr> <Tr> <Td> Prehypertension </Td> <Td> 120--139 </Td> <Td> or 80--89 </Td> </Tr> <Tr> <Td> Stage 1 Hypertension </Td> <Td> 140--159 </Td> <Td> or 90--99 </Td> </Tr> <Tr> <Td> Stage 2 Hypertension </Td> <Td> ≥ 160 </Td> <Td> or ≥ 100 </Td> </Tr> </Table>

Diastolic pressure is when the heart atria are relaxing true or false