The chapter discusses Cardiorenal Syndrome, which is the interaction between the renal and cardiovascular systems, where pathologies affecting one system can impact the other. Key points include: - Heart failure (HF) affects over 5 million Americans, with nearly 1 million hospitalized annually for acute decompensated heart failure (ADHF). - The prevalence of HF in the US is 2.3%, with an estimated 500 cases per year, potentially doubling or tripling in the next 20 years. - Most patients with HF have decreased cardiac contractility associated with subendocardial myocardial ischemia or renal impairment. - Krumholz et al. (1997) found that 41-55% of patients admitted for HF are rehospitalized within 6 months of their initial discharge. The chapter also covers the underlying neurohormonal pathways, such as atrial natriuretic peptide (ANP), B-type natriuretic peptide (BNP), endothelin (ET), renin-angiotensin-aldosterone system (RAAS), and sympathetic nervous system (SNS). It highlights the cycle of Cardiorenal Syndrome, where HF therapies can initially worsen renal function but later improve it. Key clinical factors include the definition of worsening renal function, which affects the identification of patients at risk for mortality. Treatment options for Cardiorenal Syndrome are discussed, emphasizing the role of RAAS inhibitors in managing left ventricular dysfunction and preventing progressive renal dysfunction in diabetic patients. ACE inhibitors, despite elevating creatinine and potassium levels, are recommended to continue as long as renal dysfunction does not deteriorate and severe hyperkalemia does not develop. Diuretics can lead to worsening renal function, and aggressive diuresis is a target of treatment. The chapter also mentions the importance of inflammation and volume overload in the treatment of Cardiorenal Syndrome, with the UNLOAD trial highlighting early ultrafiltration as a potential solution for severe volume overload.The chapter discusses Cardiorenal Syndrome, which is the interaction between the renal and cardiovascular systems, where pathologies affecting one system can impact the other. Key points include: - Heart failure (HF) affects over 5 million Americans, with nearly 1 million hospitalized annually for acute decompensated heart failure (ADHF). - The prevalence of HF in the US is 2.3%, with an estimated 500 cases per year, potentially doubling or tripling in the next 20 years. - Most patients with HF have decreased cardiac contractility associated with subendocardial myocardial ischemia or renal impairment. - Krumholz et al. (1997) found that 41-55% of patients admitted for HF are rehospitalized within 6 months of their initial discharge. The chapter also covers the underlying neurohormonal pathways, such as atrial natriuretic peptide (ANP), B-type natriuretic peptide (BNP), endothelin (ET), renin-angiotensin-aldosterone system (RAAS), and sympathetic nervous system (SNS). It highlights the cycle of Cardiorenal Syndrome, where HF therapies can initially worsen renal function but later improve it. Key clinical factors include the definition of worsening renal function, which affects the identification of patients at risk for mortality. Treatment options for Cardiorenal Syndrome are discussed, emphasizing the role of RAAS inhibitors in managing left ventricular dysfunction and preventing progressive renal dysfunction in diabetic patients. ACE inhibitors, despite elevating creatinine and potassium levels, are recommended to continue as long as renal dysfunction does not deteriorate and severe hyperkalemia does not develop. Diuretics can lead to worsening renal function, and aggressive diuresis is a target of treatment. The chapter also mentions the importance of inflammation and volume overload in the treatment of Cardiorenal Syndrome, with the UNLOAD trial highlighting early ultrafiltration as a potential solution for severe volume overload.