Developing better techniques to diagnose a potentially curable form of hypertension

A multidisciplinary team of researchers and clinicians from Hudson Institute and Monash Health has refined a complex procedure, adrenal vein sampling (AVS), used to identify a surgically curable form of hypertension caused by primary aldosteronism (PA).

The work was presented by clinician-researcher Dr Jun Yang at the International Aldosterone Meeting as well as ENDO 2017 in Orlando, Florida, last month.

Last year, a team led by Dr Jun Yang, Dr Jimmy Shen and Ms Elise Forbes set up a dedicated clinic at Monash Health for looking after patients with PA, with support from the research team in the Hudson institute led by Dr Morag Young.

Hudson Institute researcher and Monash Health endocrinologist Dr Yang says the clinic aims to improve both the referral pathway for, and management of, PA, a known cause of high blood pressure.

“PA is a curable yet underdiagnosed form of high blood pressure, caused by over-production of a steroid hormone, aldosterone, from either one or both adrenal glands,” Dr Yang said. “A survey reported detection rates of less than 0.5 per cent in our local community, when the real rate of people affected is closer to between 5 and 13 per cent according to international data.”

Since the clinic was set up in 2016, success rates for the AVS procedure used to identify which patients with PA will benefit from surgery have increased from less than 50 per cent prior to 2011, to almost 100 per cent in 2017.

The number of people undergoing AVS at Monash Medical Centre has jumped from 2 in 2011 to 31 in 2016, with the number projected to double again in 2017.

“This procedure is important, because it helps us understand whether the patient will benefit from surgery. This condition carries a four- to twelve-fold greater risk of stroke, heart attack and arrhythmia than other types of hypertension. It is either curable by surgery if caused by disease in one adrenal gland, or easily treated with effective and targeted medication,” Dr Yang said.

Despite all of this, PA is underdiagnosed because it is not well understood as a common cause of hypertension, there are few clear referral pathways, and the AVS procedure is technically challenging, with success rates varying widely between centres.

“Our clinic removed these blocks to treating PA by providing a clear referral pathway for GPs and specialists, with patients coming from as far as Hobart, and through developing specialised expertise in the AVS procedure,” she said.

Associate Professor Winston Chong has been performing almost all AVS procedures since 2011, enabling him to develop a focused expertise to improve success rates. In addition, a chemical pathologist, Dr James Doery or Dr Kay Weng Choy, attends all procedures to ensure accurate labelling, measurement and reporting of the numerous blood samples collected during AVS.

The AVS database has been maintained by Dr Nicholas Chee, a Monash Health resident, since 2015, which has allowed Monash to contribute to an international AVS Study (AVIS-2) whose results were also presented at the International Aldosterone Meeting by Professor Gian Paolo Rossi from Padua, Italy.

Dr Yang and the team hope that the clinic and improved diagnosis of PA will lead to significant population health and economic impacts.

“Through better detection of PA, we can place patients on more effective and targeted drugs or appropriate treatments including surgery, whilst reducing the rates of cardiovascular complications, leading to an improved quality of life for many hypertensive patients,” she said.

Professor Peter Fuller, Head of Endocrinology at Monash Health and the Hudson Institute notes: “the Institute has for many years been recognised internationally for its work on aldosterone; the work of Dr Yang and her team represents the translation of this expertise into improved outcomes for our patients.”