Review ArticleLow-Cardiac-Output Syndrome After Cardiac Surgery
Section snippets
Risk Factors and Predictors
To date, several risk factors and predictors have been recognized (Table 1). Furthermore, a number of outcome prediction models have been developed, including the commonly used EuroSCORE, which predicts perioperative cardiovascular alterations.15 Independent significant risk factors for LCOS, including advanced age (>65 years), impaired LV function (<50%), on-pump coronary artery bypass grafting (CABG), emergency surgery or cardiopulmonary bypass (CPB), and incomplete revascularization, have
Pathophysiology
Most interventions that include CPB with cardioplegic arrest lead to myocardial dysfunction, which typically results from ischemic/reperfusion injury of the heart. The persistence of such dysfunctions may vary from temporary (up to 24 hours), for stunning, to persistent, in cases of profound ischemia and myocardial infarction. The contributing factors include preoperative myocardial dysfunction, degree of myocardial protection, systemic inflammatory responses, and alterations in signal
Hemodynamic Monitoring and Directed Therapy
The goal of perioperative hemodynamic management in cardiac surgery should be optimization of the balance between DO2 and oxygen consumption (VO2); this is especially important in patients with low CO. The individualized choice of perioperative monitoring technique depends on the type of surgery and the patient-related risk. Over time, a number of new hemodynamic monitoring methods have appeared, including real-time measurements and less-invasive approaches.40
LCOS Prevention
LCOS represents a major cardiac surgery challenge because it is associated with increased morbidity and mortality. The efforts of the surgical team aim to reduce the LCOS burden, especially in high-risk patients. Hence, the early use of numerous drugs and techniques is intended to reduce the incidence and severity of this complication.
Treatment
Treatment of LCOS is complex and is intended to increase tissue DO2 and prevent worsening organ dysfunction and failure by providing adequate hemodynamic support6 (Fig 4). If identified, the cause (eg, graft dysfunction, valvular incompetence, pericardial tamponade, residual defects) must be corrected rapidly. The first line of LCOS therapy, to be initiated as soon as the volume status is optimized, is the use of inotropes and vasodilators to improve contractility, preload, and afterload.
Conclusion
LCOS is a leading cause of morbidity and mortality after cardiac surgery, especially in high-risk patients. Inadequate myocardial protection, coupled with the patient’s status and numerous perioperative factors, including prolonged aortic cross-clamp time and myocardial ischemia, might contribute to the development of this complication. Treatment of LCOS is necessarily complex and is aimed at increasing tissue DO2 by providing adequate hemodynamic support to prevent worsening organ dysfunction
Acknowledgment
The authors thank Professor Vsevolod Kuzkov for the help with preparations of figures.
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