Cardiovascular haemodynamics and autonomic function in resistant hypertension: relation to blood pressure control

Alsharari, Reem ORCID: 0000-0002-7859-8300 (2023). Cardiovascular haemodynamics and autonomic function in resistant hypertension: relation to blood pressure control. University of Birmingham. Ph.D.

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Abstract

Introduction: Hypertension is one of the major risk factors for cardiovascular and cerebrovascular diseases such as myocardial infarction (MI) and stroke. Patients with resistant and malignant hypertension have poor prognosis and high rate of complications. Understanding the pathophysiological mechanisms underlying the severe forms of hypertension and their relationship to cardiac and endothelial function, and autonomic dysregulation is crucial to the management of blood pressure (BP). Furthermore, increased arterial stiffness, impaired cardiac function and endothelial dysfunction all act as indicators and predictors of cardiovascular events in patients with hypertension. There are 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 optimisation of antihypertensive therapy in resistant hypertension can improve cardiac mechanics, vascular and autonomic function.
Aims: To assess left ventricle (LV), vascular, and autonomic function in patients with hypertension (resistant and malignant) and in a normotensive control (NC). Also, to assess the efficacy of intensified antihypertensive treatment on myocardial mechanics, vascular and autonomic function and blood pressure variability (BPV) in patients with resistant hypertension (RH).
Methods: Cardiac haemodynamics, strain function, vascular and autonomic function were evaluated in patients with malignant hypertension (MHT), RH and in normotensive group.
Results: Patients with MHT and true RH had persistently abnormal cardiac remodelling, even after long-term intensive antihypertensive treatment, and irrespective of LV ejection fraction (EF). Stable patients with MHT and good long-term BP control still had worse cardiac remodelling compared to those with RH suggesting that impaired global longitudinal strain (GLS) was not only influenced by afterload and could be related to more prevalent myocardial fibrosis in MHT. Patients with MHT also showed low subendocardial viability ratio (SEVR) and total peripheral resistance (TPR) compared to control subjects, indicating the presence of insufficient oxygen supply and low myocardial oxygen consumption.
Endothelial dysfunction and elevated arterial stiffness were found in patients with MHT and RH; however, autonomic function was preserved in all groups.
After 8 weeks of antihypertensive treatment, cardiac strain function, endothelial function and BPV significantly improved compared with baseline in patients with true RH; however, arterial stiffness and heart rate variability (HRV) did not change.
Conclusion: This is the first detailed cardiovascular and autonomic evaluation of two extreme phenotypes of hypertension (patients with treated MHT and patients with true RH). The study demonstrates the ability and sensitivity of advanced strain imaging to unmask differential cardiac remodelling responses in patients with MHT and RH. The study also provides findings that may potentially imply that MHT has different abnormalities. Intensive antihypertensive treatment reduces office and 24-hour BP in patients with RH and has a favourable impact on cardiac and endothelial function but had no effect on HRV or arterial stiffness.

Type of Work:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

Supervisor(s):

Supervisor(s)	Email	ORCID
Thomas, G. Neil	UNSPECIFIED	orcid.org/0000-0002-2777-1847
Shantsila, Alena	UNSPECIFIED	orcid.org/0000-0002-0594-8576
Lip, Gregory	UNSPECIFIED	orcid.org/0000-0002-7566-1626