Abstract. This scientific paper explores the fundamental pathophysiological mechanisms underlying heart failure. The study provides a comprehensive analysis of how structural and functional changes in the heart contribute to impaired cardiac output and systemic complications. The paper examines key processes such as hemodynamic alterations, neurohormonal activation, ventricular remodeling, inflammation, and cellular energy deficiency. Particular emphasis is placed on the progression of heart failure from compensatory adaptations to maladaptive responses, leading to chronic dysfunction. Furthermore, the discussion highlights the systemic nature of the disease, affecting organs beyond the cardiovascular system, including the kidneys, liver, and brain. By focusing on both molecular and clinical aspects, the paper aims to enhance the understanding of heart failure as a multi-faceted syndrome. This deeper understanding supports the development of more targeted and effective therapeutic strategies. The content is intended for students, researchers, and medical professionals interested in the mechanisms and management of heart failure.