Isolated systolic hypertension
Isolated systolic hypertension, abbreviated ISH, is one of the special forms of high blood pressure (hypertension). In the German Hypertension Leagues blood pressure classification, ISH appears as a separate category alongside normal and elevated values.
So its characterized by a rise in the systolic (top) blood pressure alone, while the diastolic (bottom) values remain low or normal.
systolic >= 140 mmHg / diastolic < 90 mmHg
Depending on how high the systolic (top) value is, ISH is also divided into three severity grades:
- Grade 1: 140 - 159 (borderline ISH)
- Grade 2: 160 - 179 (manifest ISH)
- Grade 3: ≥ 180 mmHg
If the diastolic (bottom) blood pressure is noticeably low (for example around 60 to 70 mmHg), isolated systolic hypertension carries a particular risk. In this context, the resulting increased pulse pressure should also be noted.
ISH occurs almost exclusively in people aged 55 and older. ISH in under-45s is rare. Women are more likely to show the manifest form.
What causes isolated systolic hypertension?
Two main mechanisms can cause isolated systolic hypertension:
- One possible cause is a malfunction of the aortic valve. The aortic valve is at the outlet of the left ventricle to the aorta. If this valve doesnt close properly, blood can flow back toward the heart.
- Calcified (stiff) blood vessels can also lead to this form of high blood pressure. As vessels progressively calcify, they lose elasticity. That means they cant cushion the pressure increase that occurs when the heart contracts. Studies have shown that in stiff vessels there can be backflow of blood toward the heart.
Other causes of ISH can include thyroid disorders or other, less common conditions.
For that reason, isolated systolic hypertension usually needs treatment. The doctor should also examine the blood vessels.
Sources:
This article comes from BloodPressureDB – the leading app since 2011 that helps hundreds of thousands monitor their blood pressure every day.
Our content is based on carefully researched, evidence-based data and is continuously updated (as of 11/2025).
Author Sabine Croci is a qualified medical assistant with many years of experience in internal medicine and cardiology practices as well as in outpatient care, and has led BloodPressureDB's specialist editorial team since 2015. Thanks to her extensive additional qualifications as a paramedic, first responder and in various therapy and emergency areas, she provides solid, practical and reliably reviewed information.
Author Sabine Croci is a qualified medical assistant with many years of experience in internal medicine and cardiology practices as well as in outpatient care, and has led BloodPressureDB's specialist editorial team since 2015. Thanks to her extensive additional qualifications as a paramedic, first responder and in various therapy and emergency areas, she provides solid, practical and reliably reviewed information.
