Fatal fibrosis as a matter of heart

The material of the cardiology researchers from Oulu can be considered unique on the global scale. This material is used to study what factors influence development of fibrosis that leads to cardiac diseases and sudden death.

In the beginning of June, the Academy of Finland granted EUR 3.3 million to research on fibrotic diseases and steel research in the University of Oulu. The funds are intended for the strengthening of the focus areas of the University. Research on fibrotic diseases falls under the theme of lifelong health.

Fibrosis refers to fibrous tissue that forms in an organ when its own cells die. Fibrosis is most common in organs where the renewal of cells is slow or non-existent.  Such organs include, for example, the heart, lungs, liver, kidneys and pancreas.

Juhani Junttila, university researcher in the Cardiology Research Group of the University of Oulu, has specialised in cardiac fibrosis. Fibrosis is related to all cardiac diseases, and cardiac diseases are the most common cause of death in Finland.

“When a patient with coronary artery disease has a myocardial infarction, a portion of the myocardium dies as a result of lack of oxygen caused by an occlusion. The muscle cells are replaced by fibrosis,” says Junttila.

According to Junttila, coronary artery disease is the most common cause of cardiac deaths in Finland. In cardiomyopathies, such as myocarditis and alcohol-induced cardiomyopathy, formation of fibrosis causes heart failure. Junttila adds that also hypertension and hereditary factors can cause thickening of the myocardium with fibrosis.

Loops in the heart

The Cardiology Research Group of the University of Oulu is led by professor Heikki Huikuri, who will be succeeded by Juhani Junttila. This large group includes several post-doctoral researchers, doctoral candidates and partners from other scientific fields from the University of Oulu, Europe and the United States. The group has joint funding with the distinguished John Hopkins University, USA, and is funded by the National Institute of Health.

Junttila specialises in studying sudden cardiac death. The cause of sudden death can be traced down to fibrosis.

“The heart muscle cells are lined up to contract in the right direction. When fibrosis is formed between the cells, it impedes synchronised contraction and prevents electrical conduction,” explains Junttila.

A muscle conducts electricity, but fibrosis does not. When electricity is not conducted, it can lead to arrhythmia, a 'short-circuit' of the heart.

“In that case, electricity forms loops. It finds a new route and comes back,” Junttila describes.

Arrhythmias can be fatal. This kind of death may not be preceded by any symptoms.

Why does fibrosis kill young people?

When a person dies suddenly, without an obvious cause, a forensic post-mortem examination is performed. The death may be explained by cardiac fibrosis.

“Unlike elsewhere in the world, a forensic post-mortem examination is required by Finnish law when the cause of death is unknown. The material based on autopsies is the largest in the world,” says Junttila.

The Cardiology Research Group of the University of Oulu has studied material on sudden deaths in Northern Finland since 1998. Heart samples have been used to study the level of fibrosis and to isolate DNA.

“The material on sudden deaths in Northern Finland included young people who died suddenly, without any previous disease, but fibrosis was found in the heart,” says Junttila.

It is currently being studied whether genetic susceptibility explains fibrosis.

Another main theme of the research group is connection of sudden death with type 2 diabetes and coronary artery disease.

“Based on the material, over 80% of sudden cardiac deaths occurs in patients with diabetes. A new finding is that patients with coronary artery disease who do not have diabetes have a better prognosis than patients with both coronary artery disease and diabetes,” explains Junttila. Earlier MRI studies of the heart have revealed that diabetes increases formation of fibrosis in the heart.

Saving lives requires continuity

Because state research funding has decreased during the last years, Juhani Junttila thinks that funding from the Academy is critical for the continuity of research projects.

“Gene analyses are expensive. Our aim is to find genetic factors that predispose people to cardiac fibrosis that leads to sudden death in order to be able to identify at an earlier stage those in the risk group.”

The group believes that, together with the collaborators, we can develop methods to prevent formation of fibrosis.

Another aim is to find out why patients with diabetes have a risk of cardiac death due to coronary artery disease and how mortality could be decreased.

Because the research is slow and focuses on very specialised, small details, the results do not have a direct effect. According to Junttila, getting answers require several ongoing study designs and a lot of work.

In Junttila's own words, especially study of hereditary factors is close to his heart.

“These people have not contributed to their illness. If everyone is not dealt the same cards at birh, we have to do something about it. Maybe we could save a few lives.”

Cardiology Research Group

 

Original (Finnish) text and photos: Sanna Häyrynen/Oulun ylioppilaslehti (Oulu student magazine)

Main photo: University researcher Juhani Junttila studies hereditary background of sudden cardiac deaths.

 

Last updated: 1.11.2017