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A prospective evaluation of hemodynamic instability during off-pump coronary artery bypass surgery
Manisha Mishra1, Shipra Shrivastava, Ajay Dhar
1Escorts Heart Institute and Research Centre, New Delhi, India. manishamishra@yahoo.com
Insights
Identifying high-risk patients for off-pump coronary artery bypass (OPCAB) is crucial. Low ejection fraction, recent myocardial infarction, heart failure, and preoperative instability predict complications during OPCAB surgery.
Area of Science:
- Cardiovascular Surgery
- Cardiac Surgery Outcomes
- Minimally Invasive Cardiac Procedures
Background:
- Off-pump coronary artery bypass (OPCAB) is widely performed, but hemodynamic instability can occur unpredictably.
- While most patients tolerate OPCAB well, a subset requires emergency support.
- Identifying pre-operative risk factors is essential for patient management.
Purpose of the Study:
- To determine factors predicting hemodynamic instability during multivessel OPCAB.
- To identify patients at higher risk for requiring intra-aortic balloon pump (IABP) or cardiopulmonary bypass (CPB) conversion.
Main Methods:
- Prospective clinical investigation involving 500 consecutive patients undergoing multivessel OPCAB.
- Data on cardiac and extracardiac factors were collected.
- Logistic regression analysis identified predictors of hemodynamic instability.
Main Results:
- 24 (4.8%) patients experienced significant hemodynamic instability.
- 16 (3.2%) required IABP support, and 8 (1.6%) were converted to CPB.
- Predictors included ejection fraction <25%, myocardial infarction <1 month, congestive heart failure, and preoperative instability.
Conclusions:
- Patients with low ejection fraction (<25%), recent myocardial infarction (<1 month), congestive heart failure, or preoperative hemodynamic instability are at high risk for OPCAB.
- These factors can guide surgical decision-making and patient selection for OPCAB.
Objective:
Despite recognized hemodynamic derangements during cardiac displacement, most patients appear to tolerate the off-pump procedure well. However, some patients unpredictably become hemodynamically unstable requiring emergency cardiopulmonary bypass or intra-aortic balloon pump support. After an experience of 5306 multivessel off-pump coronary artery bypasses (OPCABs), this study was undertaken to determine the factors that would identify the patients who were at a higher risk for the procedure.
Design:
Prospective clinical investigation.
Setting:
Tertiary care academic cardiac care center.
Participants:
Five hundred consecutive patients undergoing multivessel OPCAB from September to December 2001.
Interventions:
Various cardiac and extracardiac factors were charted in prespecified data-entry forms. Multiple logistic regression analysis was done to determine if any identifiable factors were predictors of a higher risk of unacceptable hemodynamic instability during OPCAB. Institution of IABP support or conversion to CPB were the endpoints of the study.
Measurements And Main Results:
Of the 500 patients studied, significant hemodynamic instability developed in 24 (4.8%) patients. IABP support was instituted in 16 (3.2%) patients, and 8 (1.6%) were converted to CPB. Stepwise logistic regression identified ejection fraction <25% (p < 0.001), myocardial infarction of <1-month duration (p = 0.009), congestive heart failure (p = 0.016), and preoperative hemodynamic instability (p = 0.057) as predictors of conversion during OPCAB.
Conclusions:
Patients with low left ventricular ejection fraction <25%, myocardial infarction of <1-month duration, congestive heart failure, or preoperative hemodynamic instability constitute the high-risk group for OPCAB.