Cardiovascular haemodynamics in resistant hypertension

• Research type

  Research Study

• Full title

  Cardiovascular Haemodynamics and Autonomic Function in Resistant Hypertension: Relation to Blood Pressure Control

• IRAS ID

  244214

• Contact name

  Gregory Y.H. Lip

• Contact email

  g.y.h.lip@bham.ac.uk

• Sponsor organisation

  University of Birmingham

• Duration of Study in the UK

  2 years, 2 months, 16 days

• Research summary

  Summary of Research

  People with high blood pressure (hypertension) are at higher risk of developing stroke, heart and kidney failure. It can also lead to impaired vessel function and autonomic nervous system (the part of the nervous system responsible for control of the blood vessels).
  Hypertensive patients (controlled and uncontrolled) with abnormal heart function and impaired autonomic function have been shown to have higher mortality rates. Impairment of left ventricle strain (myocardial deformation/twist) in hypertensive patients is associated with increased arterial stiffness. Although treatment plans including drugs and lifestyle modifications can be effective in most cases of hypertension, there is a subgroup of patients which is, difficult to control. According to the European Society of Hypertension and the European Society of Cardiology (ESH/ESC) guidelines for the management of arterial hypertension, 5 to 30% of patients with arterial hypertension will develop resistant hypertension. Resistant hypertension is diagnosed when office systolic or diastolic blood pressure exceeds 140 mmHg or 90mmHg respectively despite the use of three or more antihypertensive medications, one of which is diuretic (water tablet). It is associated with poor prognosis due to a higher risk of target organ damage.
  Malignant hypertension, on the other hand, is a form of hypertension in which severe blood pressure elevations (diastolic blood pressure>120 mmHg) are accompanied by bilateral retinal haemorrhages and/or exudates, with or without papilloedema. All these categories of poorly controlled hypertensives have an adverse effect on endothelial function, cardiac mechanics and autonomic function and frequently lead to increased arterial stiffness.
  There is little or no data on the relationship between cardiac mechanics, autonomic function and vascular function in patients with malignant and resistant hypertension. It is unknown if intensive therapy in resistant hypertension can modify cardiac mechanics, vascular and autonomic function.

  Summary of Results

  People with high blood pressure (hypertension) are at higher risk of developing stroke, heart failure and kidney disease. Hypertension can also lead to impaired vessel function and autonomic nervous system (the part of the nervous system that controls the blood vessels).

  Although treatment plans including drugs and lifestyle modifications can be effective in most cases of hypertension, there is a subgroup of patients which is, difficult to control. According to the European Society of Hypertension and the European Society of Cardiology (ESH/ESC) guidelines for the management of arterial hypertension, 5 to 30% of patients with hypertension will develop resistant hypertension. Resistant hypertension is diagnosed when office systolic or diastolic blood pressure exceeds 140 mmHg or 90mmHg respectively despite the use of three or more antihypertensive medications, one of which is diuretic (water tablet).

  Malignant hypertension, on the other hand, is a severe form of hypertension in which blood pressure elevations (diastolic blood pressure>120 mmHg) are accompanied by multiple complications (bilateral retinal haemorrhages and/or exudates, with or without papilledema). All these categories of poorly controlled hypertensives have an adverse effect on vascular function, cardiac mechanics and autonomic function.

  Study aims:
  There is little or no data on the assessment of cardiac mechanics, autonomic function and vascular function in patients with malignant and resistant hypertension. So, our aim was to evaluate all three functions in these two sever forms of hypertension

  Methods:
  The study is a cross-sectional comparison of the 3 groups. 64 participants were recruited, 23 had resistant hypertension, 18 had malignant hypertension, and 23 from normal controls. Heart function was assessed by echocardiography (using ultrasound machine). Arterial stiffness (when blood vessels lose some flexibility and become stiffer) and endothelial function were assessed non-invasively. Autonomic function was assessed by heart rate variability test (measure of the variation in time between each heartbeat).

  Results
  This is a summary of the main results of the study. These are the results from all the participants combined.
  The groups were matched by age, gender, ethnicity, alcohol intake and smoking status. Hypertension groups had higher body mass index, waist to hip ratio and lower estimated glomerular filtration rate (blood test to calculate how many millilitres of waste kidneys should be able to filter in a minute). Hypertension medications used were similar between hypertensives groups, except for the higher use of diuretics (water tablets) in resistant hypertension compared to malignant hypertension (100% vs. 67%). Office blood pressure was elevated in hypertensives groups compared to normal group. Although LV ejection fraction (left ventricle pumps blood with each heartbeat) was normal in all groups, both hypertensive groups showed markedly reduced global longitudinal strain (local lengthening of the myocardium) compared to normal group. Diastolic dysfunction (when the left ventricle becomes stiff which makes it difficult for the heart chamber to fill with blood) was more prevalent in hypertensives with no differences between resistant hypertension and malignant hypertension. Arterial stiffness was increased in both hypertension groups compared to normal group. Endothelial function in both hypertensives were markedly impaired. Heart rate variability was not significantly different between three groups

  Conclusion
  Patients with resistant hypertension and malignant hypertension appeared to have impaired both cardiac and endothelial function and increased arterial stiffness. No differences were detected in autonomic function assessments between groups. These findings support the hypothesis of potential restoration of nervous system balance after prolonged hypertension exposure.

• REC name

  West Midlands - South Birmingham Research Ethics Committee

• REC reference

  18/WM/0168

• Date of REC Opinion

  5 Oct 2018

• REC opinion

  Further Information Favourable Opinion