Postoperative B-type natriuretic peptide monitoring for the assessment of the magnitude of shunting through Blalock-Taussig anastomoses.

BACKGROUND: The Modified Blalock-Taussig shunt (MBTS) is the most common palliative operation performed in patients with complex cardiac defects. Postoperative morbidity and mortality rates are high, mainly due to shunt thrombosis and over-shunting. Over-shunting may be difficult to identify postoperatively based on conventional criteria. Since plasma B-type natriuretic peptide (BNP) concentrations correlate with the magnitude of shunting in various left-to-right shunt cardiac defects, we investigated its ability to identify postoperative MBTS over-shunting. METHODS AND RESULTS: This retrospective, observational study included 42 consecutive patients (median age 9.50days, IQR: 6.00-58.25) undergoing MBTS for obstruction of the pulmonary blood flow at a tertiary referral pediatric cardiac center. The BNP threshold concentrations which accurately predicted outcome and MBTS over-shunting were derived using the ROC methodology. 443 BNP concentrations were analysed. The presence of atrio-ventricular valve regurgitation was the most important component of overall variance (72.75%). In 34 patients without regurgitation, BNP concentrations were predictive of a duration of mechanical ventilation >8days and of intensive care stay >11days, with ROC areas of 0.655 [0.597-0.719], 0.650 [0.589-0.711], a negative predictive value for the >1035pgmL-1 threshold of 0.93 and 0.96 respectively. SaO2 was less accurate for the prediction of both outcomes. In patients in whom the pulmonary flow was entirely MBTS-supplied, a BNP concentrations >1052pgmL-1 was predictive of a pulmonary-to-systemic ratio>2. CONCLUSION: In MBTS patients without atrio-ventricular valve regurgitation, maintaining BNP below 1000pgmL-1 may represent a therapeutic target to avoid over-shunting.

Thoracic epidural anesthesia improves early outcome in patients undergoing cardiac surgery for mitral regurgitation: a propensity-matched study.

OBJECTIVE: There are no large studies that investigate the effect of thoracic epidural anesthesia (TEA) combined with general anesthesia (GA) in patients undergoing valvular surgery. The authors hypothesized that TEA might improve clinically relevant endpoints in patients with primary mitral regurgitation. DESIGN: Propensity-matched study. SETTING: Cardiac surgery. PARTICIPANTS: Patients scheduled for mitral valve repair or replacement were studied. INTERVENTIONS: A propensity model was constructed to match 33 patients receiving TEA combined with GA with 33 patients receiving standard GA alone. MEASUREMENTS AND MAIN RESULTS: Overall, the TEA group suffered fewer adverse events than the GA group: 10 (30%) v 23 (10%) with p = 0.002. In particular, the TEA group had a lower incidence of pulmonary events, 6 (18%) v 15 (45%) with p = 0.02, and of cardiac events, 8 (24%) v 16 (49%) with p = 0.04. Median (interquartile) time on mechanical ventilation was reduced in the TEA group, 11 (9-15) v 17 (12-36) with p = 0.007. CONCLUSIONS: This propensity-matched study suggested that TEA might be advantageous in patients undergoing surgery for mitral regurgitation.

Predictors of cardiac troponin release after mitral valve surgery.

OBJECTIVES: Although cardiac troponin I (cTnI) measurement is used extensively as a marker of perioperative myocardial injury, limited knowledge exists in noncoronary artery bypass graft surgery. DESIGN: Observational study. SETTING: Single-center intensive care unit. INTERVENTION: None. PARTICIPANTS: One hundred eighty-five consecutive adult patients undergoing mitral valve surgery for predominant mitral regurgitation were enrolled and underwent measurement of cTnI at 24 hours after surgery. MEASUREMENTS AND MAIN RESULTS: CTnI release after mitral valve surgery was significantly associated with an adverse outcome. The optimal cTnI value for predicting adverse outcomes was 14 ng/mL. Univariate preoperative predictors of cTnI release were prior use of diuretics (p = 0.04) or a rheumatic (p = 0.006), ischemic (p = 0.004), or myxomatous (p = 0.005) etiology to mitral disease, whereas intraoperative variables predictive of cTnI release were cross-clamp time (p = 0.005), cardiopulmonary bypass time (p < 0.001), need for mitral valve replacement (p = 0.024), number of electrical cardioversions (p = 0.03), patent foramen ovale closure (p = 0.03), tricuspid valve repair (p = 0.04), need for epinephrine/norepinephrine (p = 0.004) or intra-aortic balloon pump (p = 0.03) in the operating room; and, finally, the surgeon who performed the surgery (p = 0.014). There were no postoperative predictors of excessive cTnI release. In multivariate analysis, the only predictors of cTnI release were the cardiopulmonary bypass time (odds ratio, 1.42; confidence intervals, 1.019-1.064; p = 0.001) and the infusion of epinephrine/norepinephrine in the operating room (odds ratio, 4.002; confidence intervals, 1.238-12.929; p = 0.02). CONCLUSIONS: After mitral surgery, the need for epinephrine/norepinephrine perioperatively and the cardiopulmonary bypass time independently predict a cTnI release significantly related to an adverse outcome.

N-terminal B-natriuretic Peptide after coronary artery bypass graft surgery.

OBJECTIVE: To investigate N-terminal amino-acid sequence of the B-natriuretic peptide (NT-proBNP) release and its prognostic characteristics after coronary artery bypass graft surgery with and without cardiopulmonary bypass. DESIGN: Observational study. SETTING: Teaching hospital. PARTICIPANTS: One hundred eighty-four patients. INTERVENTIONS: The authors determined plasma concentrations of NT-proBNP just before anesthesia induction and 24 hours after the end of the surgery. MEASUREMENTS AND MAIN RESULTS: NT-proBNP concentrations (median [interquartile range]) increased from 270 (75-716) pg/mL preoperatively to 1,664 (978-3,193) pg/mL on postoperative day 1 (p < 0.001), and all postoperative values were higher than the preoperative ones. NT-proBNP concentrations at day 1 were correlated to those at day 0 (r(2) = 0.34, p < 0.001). Patients showing elevated concentration of cTnI at day 1 (>14 ng/mL) had significantly (p = 0.04) higher plasma NT-proBNP levels than patients with a low cardiac troponin I concentration. Patients with prolonged intensive care unit (ICU) stay (>4 days) showed at day 1 significantly higher (p = 0.003) plasma NT-proBNP levels than patients with ICU stay <4 days. Elevated NT-proBNP at day 1 was significantly (p = 0.001) associated with in-hospital mortality, 18,584 (11,896-29,158) pg/mL versus 1,597 (965-3,034) pg/mL in survivors. CONCLUSIONS: The present results show, for the first time, that postoperative NT-proBNP levels are associated with in-hospital mortality and prolonged ICU stay after CABG surgery. These findings support the prognostic value of postoperative plasma levels of NT-proBNP.