Biomarkers in Dermal Interstitial Fluid for Early Diagnosis and Follow-up of Cardiovascular Diseases

Inclusion criteria: Group 1: Chronic heart failure with stable therapy. NYHA classification II, III and IV. Age \> 60 years. Group 2: Age 18-40 years. Exclusion criteria: * Participating in another clinical investigation which may affect the study outcome according to clinical judgement. * Previous use of sampling system used. * Pregnancy or lactating. * Any disease or condition that may be affected. * Individuals who lack the ability to fully consent to participate in the study. * Severe skin injury. * Tattoo or piercing close to sampling area. * Group 1: All forms of emergency care. * Group 1: Non-stable therapy. * Group 1: Sepsis. * Group 1: BMI \> 30kg/m2. * Group 1: Age \> 84 years. * Group 2: Known heart or vascular disease. * Group 2: Diabetes. * Group 2: Kidney disease.