I am 61, female, weigh 56kg, height 5ft 3, I have Lupus and Antiphospholipid syndrome with small vessel ischaemia and arrhythmia, at last hosp appt bp was 159/91 and was told it needed monitoring by GP which I am waiting for, took my bp today on a machine and it was 135/69, why is the systolic now ok but diastolic much lower?