2 research outputs found
Exploring haemodynamics of haemodialysis using extrema points analysis model
Background: Haemodialysis is a form of renal replacement therapy used to treat
patients with end stage renal failure. It is becoming more appreciated that
haemodialysis patients exhibit higher rates of multiple end organ damage
compared to the general population. There is also a strong emerging evidence that
haemodialysis itself causes circulatory stress. We aimed at examining
haemodynamic patterns during haemodialysis using a new model and test that
model against a normal control.
Methods: We hypothesised that blood pressures generated by each heart beat
constantly vary between local peaks and troughs (local extrema), the frequency and
amplitude of which is regulated to maintain optimal organ perfusion. We also
hypothesised that such model could reveal multiple haemodynamic aberrations
during HD. Using a non-invasive cardiac output monitoring device (Finometer®) we
compared various haemodynamic parameters using the above model between a
haemodialysis patient during a dialysis session and an exercised normal control after
comparison at rest.
Results: Measurements yielded 29,751 data points for each haemodynamic
parameter. Extrema points frequency of mean arterial blood pressure was higher in
the HD subject compared to the normal control (0.761Hz IQR 0.5-0.818 vs 0.468Hz
IQR 0.223-0.872, P < 0.0001). Similarly, extrema points frequency of systolic blood
pressure was significantly higher in haemodialysis compared to normal. In contrary,
the frequency of extrema points for TPR was higher in the normal control compared
to HD (0.947 IQR 0.520-1.512 vs 0.845 IQR 0.730-1.569, P < 0.0001) with significantly
higher amplitudes.
Conclusion: Haemodialysis patients potentially exhibit an aberrant haemodynamic
behaviour characterised by higher extrema frequencies of mean arterial blood
pressure and lower extrema frequencies of total peripheral resistance. This, in
theory, could lead to higher variation in organ perfusion and may be detrimental to vulnerable vascular beds
Characterisation of cardiomyopathy by cardiac and aortic magnetic resonance in patients new to hemodialysis
OBJECTIVES: Cardiomyopathy is a key factor in accelerated cardiovascular mortality in haemodialysis (HD) patients. We aimed to phenotype cardiac and vascular dysfunction by tagged cardiovascular magnetic resonance (CMR) imaging in patients recently commencing HD. METHODS: Fifty-four HD patients and 29 age and sex-matched controls without kidney disease were studied. Left ventricular (LV) mass, volumes, ejection fraction (EF), concentric remodelling, peak-systolic circumferential strain (PSS), peak diastolic strain rate (PDSR), LV dyssynchrony, aortic distensibility and aortic pulse wave velocity were determined. RESULTS: Global systolic function was reduced (EF 51 ± 10%, HD versus 59 ± 5%, controls, p 50% (n = 35) and the subset of HD patients without diabetes (n = 40). LV dyssynchrony was inversely correlated to diastolic function, EF and aortic distensibility. Diastolic function was inversely correlated to LV dyssynchrony, concentric remodelling, age and aortic pulse wave velocity. CONCLUSION: Patients new to HD have multiple cardiac and aortic abnormalities as characterised by tagged CMR. Cardio-protective interventions are required from initiation of therapy. KEY POINTS: • First characterisation of cardiomyopathy by tagged CMR in haemodialysis patients. • Diastolic function was correlated to LV dyssynchrony, concentric remodelling and aortic PWV. • Reductions in strain localised to the septal and anterior wall. • Bioimpedance measures were unrelated to LV strain, suggesting volume-independent pathogenetic mechanisms. • Multiple abnormalities persisted in the HD patient subset with preserved EF or without diabetes