Modern cardiac intensive care units (CICU) are managing progressively more complex cardiovascular patients with multiorgan dysfunctions and non-cardiac comorbidities, including respiratory failure (RF) that requires non-invasive and invasive ventilation. Heart-lung interactions are challenging, even more in cardiovascular conditions, such as pulmonary edema, cardiogenic shock (CS), or cardiac arrest. Despite recent improvements in non-invasive diagnostics (i.e., echocardiography and lung ultrasound), right heart catheterization (RHC) remains an essential tool for understanding cardiac and pulmonary physiology and guiding therapies. Compared to ultrasounds, RHC can provide continuous hemodynamic monitoring and assessment, and it is independent from limitations, such as artifacts and inadequate acoustic windows, especially in the acute setting. Considering the low complication rate, RHC is a safe diagnostic instrument when performed by properly trained physician. Intensivists should be able to perform a complete RHC which can be very useful in several scenarios: to optimize ventilation parameters, to identify cardiogenic shock phenotypes, to adequate diuretic, vasopressors and inotropic therapies, to evaluate right ventricle failure, to upgrade with the most appropriate temporary mechanical circulatory support (MCS), to determine if a patient is suitable for permanent LVAD implantation or for orthotopic cardiac transplant, to perform a complete and accurate follow-up of patients after receiving heart replacement therapies, to better understand hemodynamics of valvular heart disease before percutaneous or surgical treatments. In conclusion, RHC is a critical diagnostic tool for the management and prognosis of patients with heart failure due to a wide variety of etiologies.