The rationale for mechanical support of the heart during myocardial dysfunction is to restore hemodynamic stability when pharmacological interventions fail. However, mechanical support of the heart serves as a bridge to more invasive interventions rather than definitive treatment.
The rationale for mechanical ventilator support in post-resuscitation myocardial dysfunction patients is to improve systemic oxygenation in settings of pulmonary edema by increasing functional residual capacity. This intervention typically reduces intrapulmonary shunting. Equally importantly, mechanical ventilation is also used to reduce excessive work of breathing. Minimal positive end-expiratory pressure should be applied, and it should be titrated so as to preclude hemodynamic decrements, particularly decreases in cardiac output.
Intra-aortic balloon counterpulsation support is indicated for patients with post-resuscitation myocardial dysfunction refractory to pharmacological interventions, refractory angina with or without hypotension, or refractory malignant ventricular arrhythmias, and as a transitional option for patients who fail efforts to reduce cardiopulmonary bypass after surgical operations. The clinical benefit of prolonged intra-aortic balloon counterpulsation support is not securely documented. More often, the intra-aortic balloon counterpulsation allows for more definitive therapy including elective coronary angioplasty, coronary artery bypass surgery, or heart transplantation.
Left ventricular assist devices and extracorporeal membrane oxygenation are the most complex cardiac assist options. The left ventricular assist device is used in cardiac surgery after unsuccessful attempts are made to wean the patient from cardiopulmonary bypass. Extracorporeal membrane oxygenation has been used, with limited success, to treat refractive hypoxemia in adults and for respiratory distress syndrome.
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