Tag Archives: Heart

Brain Activity and Heart Disease – a New Mechanism

The amygdala is a key component in the ‘salience network’ of the brain. This network is activated in conditions of fear and stress. A recent elegant paper in Lancet [1] examined the relationship, first, between amygdala activation (measured by PET scanning) and cardiovascular outcomes, and second, between activation of the amygdala and certain mediators of cardiovascular disease concerned with stimulation of bone marrow to produce inflammatory cells and with arterial inflammation. They showed positive correlations in all cases. I am interested in causal modelling,[2] [3] and I was therefore provoked by the authors’ ‘mediation model’, which I take to be a form of structural equation modelling. This suggested that only half of the amygdala’s ‘effect’ on cardiovascular disease could be explained by the two mechanisms proposed above (production of inflammatory cells and arterial inflammation). This paper represents a potential step change in understanding brain-body interactions, but I await replication with interest.

— Richard Lilford, CLAHRC WM Director

References:

  1. Tawakol A, Ishai A, Takx RAP, et al. Relation between resting amygdalar activity and cardiovascular events: a longitudinal and cohort study. Lancet. 2017; 389: 834-45.
  2. Lilford RJ, Girling AJ, Sheikh, et al. Protocol for evaluation of the cost-effectiveness of ePrescribing systems and candidate prototype for other related health information technologies. BMC Health Serv Res. 2014; 14: 314.
  3. Watson SI & Lilford RJ. Essay 1: Integrating multiple sources of evidence: a Bayesian perspective. In: Challenges, solutions and future directions in the evaluation of service innovations in health care and public health. Southampton (UK): NIHR Journals Library, 2016.

A Device for Failing Hearts

Back in 2005 I was approached by Sally Davies, then languishing as deputy director general of Research and Development, and asked to evaluate the utility of a trial of left ventricular assist devices (LVADs) for heart failure. We elicited a Bayesian prior from a chapter of surgeons from the American Society of Heart Surgeons. This prior was the basis for a value of information study,[1] which suggested that expensive LVAD technology might be a bridge too far for the hard-pressed NHS. Anyway, the world moves on and the New England Journal of Medicine has recently carried out a trial comparing two different LVADs, one more sophisticated (type 3) than the original version we studied (type 2).[2] The latest version had less problems with clotting up of the device, but survival free of a serious stroke at six months was similar, at over 80% in both groups – quite high considering how sick these patients were. The article has some extremely good diagrams explaining the devices. These devices are sometimes used to rest the heart, for example in a case of inflammation of the heart muscle. Most often they are used when the heart muscle packs up permanently, say as a result of heart attacks. In that case LVADs can be used to keep a person alive until a match can be found for a heart transplant, so called ‘bridge to transplant’, or as a permanent solution. However, I think the devices are themselves a bridge to a more subtle regenerative medicine approach based on stem cells.

— Richard Lilford, CLAHRC WM Director

References:

  1. Girling AJ, Freeman G, Gordon JP, Poole-Wilson P, Scott DA, Lilford RJ. Modeling payback from research into the efficacy of left-ventricular assist devices as destination therapy. Int J Technol Assess Health Care. 2007; 23(2): 269-77.
  2. Mehrea MR, Naka Y, Uriel N, et al. A Fully Magnetically Levitated Circulatory Pump for Advanced Heart Failure. New Engl J Med. 2017; 376: 440-50.