Right-sided heart failure is diagnosed by elevations in right-sided filling pressures, specifically central venous pressure. Careful examination is required to rule out TR as the primary cause of the central venous pressure elevation, with the caveat that acute TR can also indicate a failing right ventricle. A high central venous pressure indicates the inability of the right heart to adequately pump the venous return volume into the pulmonary circulation. Elevation in PA pressures is indicative of pulmonary hypertension.

The combination of high central venous pressure and high PA pressures indicates RV dysfunction. This scenario can be difficult to manage. Attempts to elevate systemic perfusion pressure with α-agonists can worsen pulmonary hypertension. Administration of vasodilators to lower pulmonary pressures results in systemic hypotension. In this setting, it is often prudent to return to CPB, relieve ventricular distention, and improve myocardial perfusion. During this "rest period," adjustments in inotropic therapy, ventilation, and cardiac rhythm can be instituted. Optimization of acid-base status, temperature, and hemoglobin concentration should also be performed. Separation from bypass can then be attempted again.

Inotropic agents effective in this setting are those with high degrees of β-adrenergic potency and potent vasodilation in the pulmonary vasculature. Commonly employed agents include dobutamine, epinephrine, and the phosphodiesterase-III (PDE-III) inhibitors amrinone and milrinone. α-Agonists can be required to counteract systemic vasodilation. Vasopressin can also be used for systemic vasoconstriction and has little effect on the pulmonary vasculature due to absence of local vasopressin receptors.

Inhaled vasodilators are also useful for afterload reduction in the management of acute RV dysfunction. Inhaled agents selectively affect the pulmonary vasculature, thus avoiding the systemic hypotension induced by IV agents, and can improve perfusion-ventilation matching in patients with hypoxemia. Case series and small trials indicate that aerosolized vasodilators, compared to IV agents, are associated with improved RV performance in cardiac surgery. Although aerosolized milrinone, iloprost, epoprostenol, and inhaled nitric oxide (iNO) have each been evaluated in the context of cardiac surgery, iNO is common in clinical practice. Advantages of nitric oxide include its potency, extremely short half-life, and minimal systemic effects. However, methods of iNO delivery, scavenging of waste gases, and high cost remain as obstacles to its clinical utility.

References

• Elmi-Sarabi M, Jarry S, Couture EJ, et al. Pulmonary vasodilator response of combined inhaled epoprostenol and inhaled milrinone in cardiac surgical patients. Anesth Analg. 2023;136:282-294.
• Haddad F, Elmi-Sarabi M, Fader E, et al. Pearls and pitfalls in managing right heart failure in cardiac surgery. Curr Opin Anaesthesiol. 2016;2968-79.
• Humbert M, Kovacs G, Hoeper MM, et al; ESC/ERS Scientific Document Group. 2022 ESC/ERS guidelines for the diagnosis and treatment of pulmonary hypertension. Eur Respir J. 2023;61:2200879.
• Vandenheuvel M, Bouchez S, Wouters P, Mauermann E. Assessing right ventricular function in the perioperative setting, part I: echo-based measurements. Anesthesiol Clin. 2019;37:675-695.