Outcome after valve replacement for severe aortic stenosis associated with reduced left ventricular ejection fraction.

BACKGROUND AND AIM OF THE STUDY: Because valve replacement for aortic stenosis (AS) remains a difficult surgical challenge in the presence of left ventricular dysfunction, the immediate and long-term outcomes, and evolution of left ventricular ejection fraction (LVEF) in this setting, were analyzed. METHODS: Forty-three consecutive patients with severe AS (valve area < or =1 cm2) and reduced LVEF (< or =40%) who underwent valve replacement surgery at the authors' institution between April 1998 and December 2003 and were studied retrospectively. RESULTS: Preoperative characteristics included: LVEF 33 +/- 6%, mean transaortic pressure gradient 46 +/- 13 mmHg, and aortic valve area 0.58 +/- 0.15 cm2. Concomitant coronary artery bypass grafting was performed in 15 patients (35%). Perioperative (30-day) mortality was 2.3%, with 39.5% morbidity. During a mean follow up of 33.4 +/- 17.6 months, eight patients died. The Kaplan-Meier estimate of five-year survival was 75.3%. Postoperatively, none of the survivors remained in NYHA functional classes III-IV. The postoperative LVEF assessed in 81.8% of survivors had improved. Multivariate analysis associated improved LVEF with a higher preoperative mean transaortic pressure gradient (p = 0.0009) and a higher preoperative LVEF (p = 0.02). CONCLUSION: Patients with severe AS and reduced LVEF can undergo valve replacement with low perioperative mortality and moderate postoperative morbidity. Good long-term survival with good NYHA functional status and improved LVEF can be obtained.

Efficacy of esmolol as a myocardial protective agent during continuous retrograde blood cardioplegia.

OBJECTIVE: Esmolol, an ultra-short-acting beta-blocker, is known to attenuate myocardial ischemia-reperfusion injury. The aim of this study was to compare the effects of esmolol and potassium on myocardial metabolism during continuous normothermic retrograde blood cardioplegia. METHODS: Forty-one patients operated on for isolated aortic valve stenosis were randomly assigned to continuous coronary infusion with either potassium or esmolol during cardiopulmonary bypass. Myocardial metabolism was assessed by measuring the transmyocardial gradient of oxygen content indexed to left ventricular mass of glucose, lactate, and nitric oxide. To do so, blood samples were simultaneously withdrawn upstream (in the cardioplegia line) and downstream of the myocardium (in the left coronary ostium) 10 and 30 minutes after aortic crossclamping. RESULTS: Although the cardioplegia flow rate and pressure were similar, esmolol markedly reduced the transmyocardial gradient of oxygen content indexed to left ventricular mass compared with potassium: 13 +/- 6 vs 20 +/- 6 mL of oxygen per liter of blood per 100 g of myocardium, respectively, at 10 minutes and 16 +/- 8 vs 24 +/- 8 mL of oxygen per liter of blood per 100 g of myocardium, respectively, at 30 minutes (P =.009). Coronary glucose and lactate transmyocardial gradients were similar in both groups, indicating adequate myocardial perfusion in all patients at all times. In addition, during retrograde cardioplegia, esmolol showed a lower nitric oxide release compared with that caused by potassium (39 +/- 49 micro mol x L(-1) for potassium vs 14 +/- 8 micro mol x L(-1) for esmolol at 10 minutes and 39 +/- 47 micro mol x L(-1) for potassium vs 6 +/- 8 micro mol x L(-1) for esmolol at 30 minutes, P =.05). However, hemodynamic parameters and plasma troponin I levels remained unchanged postoperatively between the 2 types of cardioplegia. CONCLUSION: Esmolol provides potent myocardial protection in hypertrophied hearts, at least in part, by reducing myocardial oxygen metabolism.

Frequency, risk factors, and outcome of hyperlactatemia after cardiac surgery.

STUDY OBJECTIVE: To determine the respective frequencies, risk factors, and outcomes of no hyperlactatemia (NHL), immediate hyperlactatemia (IHL), or late hyperlactatemia (LHL) > 3 mmol/L after cardiac surgery. DESIGN: Prospective and observational study. SETTING: Cardiac surgery ICU in a 130-bed private community nonteaching hospital. PATIENTS: Consecutive patients (n = 325) undergoing cardiopulmonary bypass (CPB) for cardiac surgery. INTERVENTION: None. MEASUREMENTS: Arterial blood gas levels and lactate concentrations were measured at ICU admission, 4 h after surgery, between 6 h and 16 h after surgery, and on day 1. MAIN RESULTS: Sixty-seven patients (20.6%) had an IHL on ICU admission, and 56 patients (17.2%) acquired LHL during their ICU stay. ICU mortality was 1.5% for NHL, 3.6% for LHL, and 14.9% for IHL groups (p < 0.0001). The three groups differed significantly for elective surgery, type of operation, CPB duration, intraoperative mean arterial pressure, and intraoperative and postoperative use of vasopressor. Independent risk factors for IHL were nonelective surgery, CPB duration, and intraoperative use of vasopressor. Logistic regression identified hyperglycemia and epinephrine therapy for LHL as postoperative risk factors. Receiver operating characteristic curves showed that IHL more accurately predicted ICU mortality than LHL. CONCLUSIONS: Hyperlactatemia is common after cardiac surgery. A lactate threshold of 3 mmol/L at ICU admission is able to identify a population at risk of morbidity and mortality after cardiac surgery.