Alexander J.C. Mittnacht

Multisite near-infrared spectroscopy predicts elevated blood lactate level in children after cardiac surgery.

OBJECTIVES To determine if a relationship exists between regional oxyhemoglobin saturation (rSO(2)) measured at various body locations by near-infrared spectroscopy (NIRS) and blood lactate level in children after cardiac surgery. DESIGN A prospective, observational study. SETTING A pediatric cardiac intensive care unit in a university hospital. PARTICIPANTS Twenty-three children undergoing repair of congenital heart disease. Patients with single-ventricle physiology and/or residual intracardiac shunts were excluded. INTERVENTIONS None. MEASUREMENTS AND MAIN RESULTS Cerebral, splanchnic, renal, and muscle rSO(2) values were recorded every 30 seconds via NIRS for 24 hours postoperatively. Blood lactate levels measured minimally at 0, 2, 4, 6 and 24 hours postoperatively were correlated with rSO(2) values derived by averaging all values recorded during the 60 minutes preceding the blood draw. Twenty-three patients were enrolled with 163 lactate measurements and more than 39,000 rSO(2) observations analyzed. Cerebral rSO(2) had the strongest inverse correlation with lactate level followed by splanchnic, renal, and muscle rSO(2) (r = -0.74, p < 0.0001, r = -0.61, p < 0.0001, r = -0.57, p < 0.0001, and r = -0.48, p < 0.0001, respectively). The correlation improved by averaging the cerebral and renal rSO(2) values (r = -0.82, p < 0.0001). Furthermore, an averaged cerebral and renal rSO(2) value <or=65% predicted a lactate level >or=3.0 mmol/L with a sensitivity of 95% and a specificity of 83% (p = 0.0001). CONCLUSIONS Averaged cerebral and renal rSO(2) less than 65% as measured by NIRS predicts hyperlactatemia (>3 mmol/L) in acyanotic children after congenital heart surgery. Hence, this noninvasive, continuous monitoring tool may facilitate the identification of global hypoperfusion caused by low cardiac output syndrome in this population.

Activation and Entrainment Mapping of Hemodynamically Unstable Ventricular Tachycardia Using a Percutaneous Left Ventricular Assist Device

OBJECTIVES Our goal was to investigate the effects of percutaneous left ventricular assist device (pLVAD) support during catheter ablation of unstable ventricular tachycardia (VT). BACKGROUND Mechanical cardiac support during ablation of unstable VT is being increasingly used, but there is little available information on the potential hemodynamic benefits. METHODS Twenty-three consecutive procedures in 22 patients (ischemic, n = 11) with structural heart disease and hemodynamically unstable VT were performed with either pLVAD support (n = 10) or no pLVAD support (intra-aortic balloon pump counterpulsation, n = 6; no support, n = 7). Procedural monitoring included vital signs, left atrial pressure, arterial blood pressure, cerebral perfusion/oximetry, VT characteristics, and ablation outcomes. RESULTS The pLVAD group was maintained in VT significantly longer than the non-pLVAD group (66.7 min vs. 27.5 min; p = 0.03) and required fewer early terminations of sustained VT for hemodynamic instability (1.0 vs. 4.0; p = 0.001). More patients in the pLVAD group had at least 1 VT termination during ablation than non-pLVAD patients (9 of 10 [90%] vs. 5 of 13 [38%]; p = 0.03). There were no differences between groups in duration of cerebral deoxygenation, hypotension or perioperative changes in left atrial pressure, brain natriuretic peptide levels, lactic acid, or renal function. CONCLUSIONS In patients with scar-related VT undergoing catheter ablation, pLVAD support was able to safely maintain end-organ perfusion despite extended periods of hemodynamically unstable VT. Randomized studies are necessary to determine whether this enhanced ability to perform entrainment and activation mapping will translate into a higher rate of clinical success.

Extubation in the operating room after congenital heart surgery in children

OBJECTIVE Early extubation in the operating room after surgery for congenital heart disease has been described; however, postoperative mechanical ventilation in the intensive care unit remains common practice in many institutions. The goal of this study was to identify perioperative factors associated with not proceeding with planned operating room extubation. METHODS We performed a retrospective chart review of 224 patients (aged 1 month to 18 years, median 20 months) undergoing surgery for congenital heart defects requiring cardiopulmonary bypass. Patients mechanically ventilated preoperatively were excluded. A stepwise logistic regression model was used to test for the independent influence of various perioperative factors on extubation in the operating room. RESULTS Overall, 79% of patients were extubated in the operating room. Younger age and longer cardiopulmonary bypass time were the strongest predictors for not extubating. Each step down to a younger age group (<2, 2-4, 4-6, 6-12, >12 months) reduced the chance of extubation in the operating room by 56%. Cardiopulmonary bypass time for more than 150 minutes was associated with an 11.8-fold increased risk of not being extubated. Male gender and high inotrope requirement after cardiopulmonary bypass were also significantly associated with fewer children being extubated. CONCLUSION Extubation in the operating room after surgery for congenital heart disease was successful in the majority of patients. The strongest independent risk factors for failure of this strategy included younger age and longer cardiopulmonary bypass time.

Percutaneous hemodynamic support with Impella 2.5 during scar-related ventricular tachycardia ablation (PERMIT 1).

Background—Percutaneous left ventricular assist devices (pLVADs) are increasingly being used to facilitate ablation of unstable ventricular tachycardia (VT), but the safety profile and hemodynamic benefits of these devices have not been described in a systematic, prospective manner. Methods and Results—Twenty patients with scar VT underwent ablation with a pLVAD. Neuromonitoring using cerebral oximetry was performed to evaluate a cerebral desaturation threshold to guide the duration of activation/entrainment mapping. The efficacy of pLVAD support was tested in a controlled manner with simulated VT. Complete procedural success was achieved in 50% (n=8) of patients, who were initially inducible for sustained VT, and partial procedural success in 37% (n=6). Using a cerebral desaturation level of 55% as a lower safety limit to guide the duration of sustained VT, 3 patients (15%) developed mild acute kidney injury (all resolved), and 1 (5%) patient developed mild cognitive dysfunction. During fast simulated VT (300 ms), cerebral desaturation to ⩽55% occurred in more than half (53%) of patients tested without pLVAD support, compared with only 5% with full pLVAD support (P=0.003). Conclusions—In a consecutive series of patients with severe left ventricular dysfunction, pLVAD-supported scar VT ablation was safe and feasible. During fast simulated VT, a miniaturized axial flow pump imparted a more favorable hemodynamic profile compared with pharmacological agents alone. Cerebral oximetry is a complimentary monitoring modality during scar VT ablation, and avoidance of cerebral desaturations below a threshold of 55% may safely guide the duration of mapping during unstable VT.

Near Infrared Spectroscopy (NIRS) in Children

Near infrared spectroscopy (NIRS) is a noninvasive method for the in vivo monitoring of tissue oxygenation. Originally used predominantly to assess cerebral oxygenation, NIRS has gained widespread popularity in many clinical settings in all age groups. Changes in regional tissue oxygenation as detected by NIRS may reflect the delicate balance between oxygen delivery and consumption in more than one organ system. However, more studies are required to establish the ability of NIRS monitoring to improve patient outcome. This review provides a comprehensive description of NIRS in children.

Percutaneous Transhepatic Venous Access for Catheter Ablation Procedures in Patients With Interruption of the Inferior Vena Cava

Background— Catheter ablation of left-sided atrial arrhythmias generally is performed using a transfemoral venous approach through the inferior vena cava (IVC). In this report, we assessed the feasibility of a percutaneous transhepatic approach to ablation of left-sided atrial arrhythmias in 2 patients with interruption of the IVC. Methods and Results— Patient 1 had atrial flutter in the setting of complex congenital heart disease and prior Fontan for univentricular physiology and a single atrium. Patient 2 had atrial fibrillation. Percutaneous hepatic vein access was obtained with ultrasound and fluoroscopic guidance. Transseptal catheterization was performed in patient 2. After the procedure, the hepatic tract in patient 1 was cauterized using a bipolar radiofrequency catheter, and an Amplatzer vascular plug was used in patient 2 to obtain hemostasis. Percutaneous hepatic vein access was achieved without complications. After electroanatomical mapping, a linear lesion was placed between the single atrioventricular valve and the confluence of the hepatic veins in patient 1; this terminated the flutter, and bidirectional block was achieved. In patient 2, the pulmonary veins were electrically isolated using an extraostial approach, isolating the ipsilateral veins in pairs. Additionally, ablation of right-side atrial flutter was achieved by obtaining bidirectional block across a linear lesion between the tricuspid valve and confluence of the hepatic veins. Hemostasis of the transhepatic tract was attained in both patients. Conclusions— In patients with interrupted IVCs, a percutaneous transhepatic approach is a feasible alternative for performing catheter ablation of complex left-sided arrhythmias.

Anesthetic Considerations in the Patient With Valvular Heart Disease Undergoing Noncardiac Surgery

Valvular heart disease can be an important finding in patients presenting for noncardiac surgery. Valvular heart disease and resulting comorbidity, such as heart failure or atrial fibrillation, significantly increase the risk for perioperative adverse events. Appropriate preoperative assessment, adequate perioperative monitoring, and early intervention, should hemodynamic disturbances occur, may help prevent adverse events and improve patient outcome. This review article aims to guide the practitioner in the various aspects of anesthetic management in the perioperative care of patients with valvular heart disease. The pharmacological approach to optimization of patient outcome with drugs, such as βblockers and lipid-lowering medications (statins), is an evolving field, and recent developments are discussed in this article.

Fast-tracking in pediatric cardiac surgery--the current standing.

Fast-tracking in cardiac surgery refers to the concept of early extubation, mobilization and hospital discharge in an effort to reduce costs and perioperative morbidity. With careful patient selection, fast-tracking can be performed in many patients undergoing surgery for congenital heart disease (CHD). In order to accomplish this safely, a multidisciplinary coordinated approach is necessary. This manuscript reviews currently used anesthetic techniques, patient selection, and available information about the safety and patient outcome associated with this approach.

Factors Affecting the Decision to Defer Endotracheal Extubation After Surgery for Congenital Heart Disease: A Prospective Observational Study

BACKGROUND: Fast-tracking and early endotracheal extubation have been described in patients undergoing surgery for congenital heart disease (CHD); however, criteria for patient selection have not been validated in a prospective manner. Our goal in this study was to prospectively identify factors associated with the decision to defer endotracheal extubation in the operating room (OR). METHODS: We performed a prospective observational study of 275 patients (median age 18 months) at the Mount Sinai Medical Center (MSMC), New York, New York, and 49 patients (median age 25 months) at the University of Tokyo Hospital (UTH), Tokyo, Japan, undergoing surgery for CHD requiring cardiopulmonary bypass. These patients were all eligible for fast-tracking, including extubation in the OR immediately after surgery, according to the respective inclusion/exclusion criteria applied at the 2 sites. RESULTS: Eighty-nine percent of patients at the MSMC, and 65% of patients at the UTH were extubated in the OR. At the MSMC, all patients without aortic cross-clamp, and patients with simple procedures (Risk Adjustment for Congenital Heart Surgery [RACHS] score 1) were extubated in the OR. Among the remaining MSMC patients, regression analysis showed that procedure complexity was still an independent predictor for not proceeding with planned extubation in the OR. Extubation was more likely to be deferred in the RACHS score 3 surgical risk patients compared with the RACHS score 2 group (P = 0.005, odds ratio 3.8 [CI: 1.5, 9.7]). Additionally, trisomy 21 (P = 0.0003, odds ratio 9.9 [CI: 2.9, 34.5]) and age (P = 0.0015) were significant independent predictors for deferring OR extubation. We tested our findings on the patients from the UTH by developing risk categories from the MSMC data that ranked eligible patients according to the chance of OR extubation. The risk categories proved to predict endotracheal extubation in the 49 patients who had undergone surgery at the UTH relative to their overall extubation rate, despite differences in anesthetic regimen and inclusion/exclusion criteria. CONCLUSIONS: Preoperatively known factors alone can predict the relative chances of deferring extubation after surgery for CHD. The early extubation strategies applied in the 2 centers were successful in the majority of cases.

Risk factors for morbidity in infants undergoing tetralogy of fallot repair

Background: Primary repair of tetralogy of Fallot (TOF) has low surgical mortality, but some patients still experience significant postoperative morbidity. Aim: To review our institutional experience with primary TOF repair, and identify predictors of intensive care unit (ICU) morbidity. Settings and Design: Medium-sized pediatric cardiology program. Retrospective study. Subjects and Methods: We retrospectively reviewed all the patients with TOF and pulmonic stenosis who underwent primary repair in infancy at our institution from January 2001 to December 2012. Preoperative, operative, and postoperative demographic and morphologic data were analyzed. ICU morbidity was defined as prolonged ICU stay (≥7 days), and/or prolonged duration of mechanical ventilation (≥48 h). Statistical Analysis Used: Multiple logistic regression analysis. Results: Ninety-seven patients underwent primary surgical repair during the study period. The median age was 4.9 months (1-9 months) and the median weight was 5.3 kg (3.1-9.8 kg). There was no early surgical mortality. Incidence of junctional ectopic tachycardia (JET) and persistent complete heart block was 2 and 1%, respectively. The median length of ICU stay was 6 days (2-21 days) and median duration of mechanical ventilation was 19 h (0-136 h). By multiple regression analysis, age and weight were independent predictors of length of ICU stay, while surgical era was an independent predictor of duration of mechanical ventilation. Conclusion: Primary TOF repair is a safe procedure with low mortality and morbidity in a medium-sized program with outcomes comparable to national standards. Age and weight at the time of surgery remain significant predictors of morbidity.