Patrick I. McConnell

Accuracy of Noninvasive and Continuous Hemoglobin Measurement by Pulse Co-Oximetry During Preoperative Phlebotomy

Background: In recent years, the continuous noninvasive hemoglobin measurement has been offered by devices using advanced pulse oximetry technology. Accuracy has been established in healthy adults as well as in surgical and intensive care unit patients but not in the setting of acute hemorrhage. In this study, we evaluated the accuracy of such a device in the clinical setting of preoperative phlebotomy thereby mimicking a scenario of acute blood loss. Methods: This prospective study included patients undergoing surgical repair of congenital heart disease (CHD) for whom preoperative phlebotomy was planned. Blood was removed after the induction of anesthesia and prior to the start of the surgical procedure. Replacement with crystalloid was guided by hemodynamic variables and cerebral oxygenation measured by near-infrared spectroscopy. Hemoglobin was measured by bedside whole blood analysis (total hemoglobin [tHb]) before and after phlebotomy, and concurrent measurements from the pulse co-oximeter (noninvasive, continuous, or spot-check testing of total hemoglobin [SpHb]) were recorded. Results: The study cohort included 45 patients ranging in age from 3 months to 50 years. Preoperative phlebotomy removed an average of 9.2 mL/kg of blood that was replaced with an average of 7.2 mL/kg of crystalloid. The pre- and postphlebotomy tHb values were 13.0 ± 1.9 and 12.4 ± 1.8 g/dL, respectively. The absolute difference between the tHb and SpHb (▵Hb) was 1.2 ± 0.1 g/dL. Bland-Altman analysis revealed a bias of 0.1 g/dL, a precision of 1.5 g/dL, and 95% limits of agreement of −2.8 to 3.1 g/dL. In 52.2% of the sample sets, the SpHb was within 1 g/dL of the actual hemoglobin value (tHb), and in 80% of the sample sets, the SpHb was within 2 g/dL. No variation in the accuracy of the deviation was noted based on the patient’s age, weight, or type of CHD (cyanotic versus acyanotic). Conclusion: The current study demonstrates that the accuracy of continuous, noninvasive hemoglobin measurement was not affected by acute blood loss simulated by preoperative phlebotomy. Although the device provided a clinically acceptable correlation with the actual hemoglobin value and offers the value of a continuous trend monitor, given the precision of the device, it does not appear that actual transfusion decisions can be based on the device alone.

A single-center strategy to minimize blood transfusion in neonates and children undergoing cardiac surgery.

The transfusion of blood products in the setting of uncontrolled bleeding is unquestionably lifesaving. However, in many instances, the decision to transfuse is based on physician gestalt rather than medical evidence. When indications for transfusion are unclear, the benefits of blood products must be balanced against their significant risks and associated costs. As our institution is a referral center for patients of Jehovahs Witness faith, this population has pushed our development of techniques to achieve the goal of bloodless surgery. Our practices in caring for this population have become our standard practice for managing all patients undergoing congenital cardiac surgery.

Variability in noncardiac surgical procedures in children with congenital heart disease

BACKGROUNDnThe purpose of this study was to examine the volume and variability of noncardiac surgeries performed in children with congenital heart disease (CHD) requiring cardiac surgery in the first year of life.nnnMETHODSnPatients who underwent cardiac surgery by 1 year of age and had a minimum 5-year follow-up at 22 of the hospitals contributing to the Pediatric Health Information System database between 2004 and 2012 were included. Frequencies of noncardiac surgical procedures by age 5 years were determined and categorized by subspecialty. Patients were stratified according to their maximum RACHS-1 (Risk Adjustment in Congenital Heart Surgery) category. The proportions of patients across hospitals who had a noncardiac surgical procedure for each subspecialty were compared using logistic mixed effects models.nnnRESULTSn8857 patients underwent congenital heart surgery during the first year of life, 3621 (41%) of whom had 13,894 noncardiac surgical procedures by 5 years. Over half of all procedures were in general surgery (4432; 31.9%) or otolaryngology (4002; 28.8%). There was significant variation among hospitals in the proportion of CHD patients having noncardiac surgical procedures. Compared to children in the low risk group (RACHS-1 categories 1-3), children in the high-risk group (categories 4-6) were more likely to have general, dental, orthopedic, and thoracic procedures.nnnCONCLUSIONSnChildren with CHD requiring cardiac surgery frequently also undergo noncardiac surgical procedures; however, considerable variability in the frequency of these procedures exists across hospitals. This suggests a lack of uniformity in indications used for surgical intervention. Further research should aim to better standardize care for this complex patient population.

Preliminary Experience in the Use of an Extracellular Matrix (CorMatrix) as a Tube Graft: Word of Caution

A number of materials have been used for the repair of congenital heart disease. However, an ideal material is yet to be discovered. Decellularized extracellular matrix from porcine small intestinal submucosa (CorMatrix) has been developed and commercialized as a biological tissue substitute. This has been used for valvuloplasty, sepal defect repair, or angioplasty as a patch. In this study, we demonstrate our preliminary experience using CorMatrix as a tube graft. A retrospective review of 13 patients who underwent cardiac surgery using CorMatrix as an interposition graft was performed (10 patients for central pulmonary artery reconstruction in comprehensive stage II surgery for hypoplastic left-sided heart syndrome and 3 patients for aortic arch reconstruction in interrupted aortic arch). At a mean follow-up of 9.7 months, 8 of 10 patients who underwent central pulmonary artery reconstruction using CorMatrix tube showed progressive significant stenosis. One patient underwent replacement of the CorMatrix tube with a homograft because of severe stenosis after the placement of a stent. All 3 patients who had aortic arch reconstruction with the CorMatrix tube demonstrated no stenosis, no dilatation, and no aneurysm formation. Although angioplasty using CorMatrix as an interposition tube vascular graft demonstrated no adverse event in the aortic position in short term, a high rate of intimal hyperplasia formation with significant stenosis was found in the low-pressure small-diameter system. Longer follow-up is required to assess the growth potential of the arterial conduit. CorMatrix may not be the ideal material as conduit in the low-pressure small-diameter system to provide long-term durable outcomes.

Surveillance transbronchial biopsies in infant lung and heart–lung transplant recipients

There are limited published data on surveillance TBB for the identification of allograft rejection in infants after lung or heart‐lung transplantation. We performed a retrospective review of children under one yr of age who underwent lung or heart–lung transplant at our institution. Since 2005, four infants were transplanted (three heart–lung and one lung). The mean age (±s.d.) at the time of transplant was 5.5 ± 2.4 (range 3–8) months. A total of 16 surveillance TBB procedures were completed in both inpatient and outpatient settings, with a range of 3–7 performed per patient. A minimum of five acceptable tissue pieces with expanded alveoli were obtained in 81% (13/16) of TBB procedures and a minimum of three pieces in 88% (14/16). There was no evidence of acute allograft rejection in 88% (14/16) of TBB procedures. One TBB procedure yielded two tissue specimens demonstrating A2 acute allograft rejection. One TBB procedure failed to yield tissue with sufficient alveoli. Additionally, B‐grade assessment identified B0 in 50% (8/16), B1R in 12% (2/16), and BX (ungradeable or insufficient sample) in 38% (6/16) of biopsy procedures, respectively. In conclusion, TBB may be safely performed as an inpatient and outpatient procedure in infant lung and heart–lung transplant recipients and may provide adequate tissue for detecting acute allograft rejection and small airway inflammation.

Comprehensive evaluation of lung allograft function in infants after lung and heart-lung transplantation

BACKGROUNDnLimited data exist on methods to evaluate allograft function in infant recipients of lung and heart-lung transplants. At our institution, we developed a procedural protocol in coordination with pediatric anesthesia where infants were sedated to perform infant pulmonary function testing, computed tomography imaging of the chest, and flexible fiberoptic bronchoscopy with transbronchial biopsies.nnnMETHODSnA retrospective review was performed of children aged younger than 1 year who underwent lung or heart-lung transplantation at our institution to assess the effect of this procedural protocol in the evaluation of infant lung allografts.nnnRESULTSnSince 2005, 5 infants have undergone thoracic transplantation (3 heart-lung, 2 lung). At time of transplant, the mean ± standard deviation age was 7.2 ± 2.8 months (range, 3-11 months). Of 24 procedural sessions performed to evaluate lung allografts, 83% (20 of 24) were considered surveillance where the patients were completely asymptomatic. Of the surveillance procedures, 80% were performed as an outpatient, whereas 20% were done as inpatients during the lung or heart-lung transplant post-operative period before discharge home. Sedation was performed with propofol alone (23 of 24) or in addition to ketamine (1 of 24) infusion; mean sedation time was 141 ± 39 minutes (range, 70-214) minutes. Of the 16 outpatient procedures, patients were discharged after 14 (88%) on the same day, and after 2 (12%) were admitted for observation, with 1 being due to transportation issues and the other due to fever during the observation period.nnnCONCLUSIONSnA comprehensive procedural protocol to evaluate allograft function in infant lung and heart-lung transplant recipients was performed safely as an outpatient.

Extracorporeal Membrane Oxygenation Outcomes After the Comprehensive Stage II Procedure in Patients With Single Ventricles

Outcomes for extracorporeal membrane oxygenation (ECMO) have been described for patients with single ventricle physiology (SVP) undergoing cavopulmonary connection (Glenn procedure). An alternative surgical pathway for patients with SVP consists of an initial hybrid procedure followed by a comprehensive Stage II procedure. No data exist describing the outcomes of patients requiring ECMO after the comprehensive Stage II procedure. The goal of this study is to describe the outcomes for patients who required ECMO after the comprehensive Stage II procedure. Data from the Extracorporeal Life Support Organization (ELSO) registry from 2001 to 2015 for children undergoing the comprehensive Stage II procedure older than 3 months of age were retrospectively analyzed. Demographics and ECMO characteristics were recorded. A total of six children required ECMO support after the comprehensive Stage II procedure (2 males, 4 females). Four patients had the diagnosis of hypoplastic left heart syndrome and two patients had the diagnosis of an unbalanced atrioventricular septal defect. Bypass time was 242.8u2009±u2009110.9 min and cross-clamp time was 91.2u2009±u200946.2 min for the surgical procedure. Weight was 5.8u2009±u20091.3 kg and age was 150.2u2009+u200937.9 days at time of ECMO. ECMO duration was 276.0u2009±u2009218.1 h. Complications during the ECMO run included hemorrhage in four patients (67%), renal dysfunction in two patients (33%), and neurologic injury in two patients (33%). Four patients (67%) were discharged alive after ECMO decannulation. Despite being a much more extensive surgical procedure, the morbidity and mortality after ECMO in patients undergoing the comprehensive Stage II procedure are similar to those in patients undergoing the Glenn procedure. If needed, ECMO support is reasonable for patients after the comprehensive Stage II procedure.

Echocardiographic Analysis of an Extracellular Matrix Tricuspid Valve

(Echocardiography 2014;31:E264–E266)Key words: CorMatrix, tricuspid valve, extracellular matrix graft, bioprosthetic valve, echocardiogra-phy, three-dimensional echocardiographyA 26-year-old woman with the diagnosis of adysplastic tricuspid valve was referred for surgicalcorrection due to increasing frequency of dysp-nea on exertion and presyncopal symptoms.Preoperative transthoracic echocardiogram doc-umented severely dilated right-sided chambersand severe tricuspid regurgitation (movie clipS1). The patient was clear that if a repair wasunsuccessful, she did not want a mechanicalvalve replacement.In the operating room, preoperative trans-esophageal echocardiography (TEE) (Vivid I, GEHealthcare, Wauwatosa, WI, USA) again demon-strated severe tricuspid regurgitation (movie clipS2). Initial attempts at repair with closure of mul-tiple leaflet fenestrations as part of performing amodified cone repair and then additionallydownsizing the annulus with a 36-mm tricuspidvalve annuloplasty ring were attempted but ulti-mately failed due to abnormal anterior leafletattachment to the dilated right ventricular (RV)free wall. A custom-made 34-mm extracellularmatrix cylinder valve (ECM-CV; CorMatrix Car-diovascular, Roswell, GA, USA) was used forreplacement. The cylinder valve was constructedfrom a single sheet of ECM fashioned into a cylin-der with a valve height of 1.5 times that of thediameter. It was sewn in circumferentially at theannulus and tacked with pledgeted suture to theRV septum, the RV free wall (there was no ante-rior papillary muscle and the moderator bandwas too remote) and the true posterior papillarymuscle. TEE showed no tricuspid regurgitation inone view (movie clip S3, Fig. 1) and moderateregurgitation in another view (movie clip S4,Fig. 2). Thus, the mechanism of regurgitationwas not entirely clear. Three-dimensional (3D)images clearly showed the mechanism ofregurgitation was through a central coaptationpoint and not due to another mechanism (movie

Hybrid Palliation: Outcomes After the Comprehensive Stage 2 Procedure

BACKGROUNDnThe comprehensive stage 2 procedure (CS2) follows initial hybrid stage 1 palliation for patients with single-ventricle physiology. The goal of this study was to describe CS2 outcomes and differences between survivors of CS2 (s-CS2) and nonsurvivors (nons-CS2).nnnMETHODnAll patients in The Society of Thoracic Surgeons Congenital Heart Surgery Database who underwent CS2 as index operation from 2010 to 2016 were included. Preoperative, operative, and postoperative data were analyzed, stratified by operative mortality (in-hospital or within 30 days of the operation), with univariate comparisons using χ2, Fisher exact, or Wilcoxon rank sum tests.nnnRESULTSnOf 209 patients (49 centers) who met inclusion criteria, 141 patients had the diagnosis of hypoplastic left heart syndrome. Overall operative mortality was 12.4% (26 of 209). s-CS2 had a lower prevalence of preoperative extracorporeal membrane oxygenation use (0.0% vs 7.7%, pxa0= 0.02) and less frequently underwent concomitant tricuspid valve procedures at the time of the operation (1.1% vs 11.5%, pxa0= 0.01) than nons-CS2. Postoperatively, the prevalence of any of six The Society of Thoracic Surgeons Congenital Heart Surgery Database major complications was higher in nons-CS2 than in s-CS2 (53.9% vs 23.0%, p < 0.01), including a higher prevalence of renal failure (7.7% vs 0.6%, pxa0= 0.04) and postoperative extracorporeal membrane oxygenation use (46.2% vs 2.7%, p < 0.01). There were no other preoperative, operative, or postoperative differences between the two groups.nnnCONCLUSIONSnOperative mortality associated with the CS2 procedure is substantial, especially for patients receiving extracorporeal membrane oxygenation support after CS2. No obvious modifiable variables were noted between patients who died and those who survived.

Cardiac Unloading with an Implantable Interatrial Shunt in Heart Failure: Serial Observations in an Ovine Model of Ischemic Cardiomyopathy

ABSTRACT Background: Patients with dilated cardiomyopathy often have progressive heart failure with systolic dysfunction, ventricular remodeling and clinical decompensation heralded by elevations of filling pressures. Our hypothesis is that an interatrial shunt device can regulate left atrial pressure and stabilize left ventricular function without overloading the right heart. Methods: Sheep (N = 21) were subjected to repeat coronary microembolization until left ventricular dysfunction with reduced LVEF was documented. After study group assignment, animals were chronically instrumented during thoracotomy. Shunts were implanted in n = 14 and n = 7 were sham controls. Hemodynamic and echocardiographic responses were serially evaluated for 12 weeks. Results: Comparisons at study termination showed improved outcomes with interatrial shunting (LVEF 46 ± 11% vs. 18 ± 3%; fractional shortening 19 ± 6% vs. 6 ± 1%; ventricular septal thickness 1.2 ± 0.2 cm vs. 1.0 ± 0.3 cm; left atrial pressure 14 ± 3 mmHg vs. 25 ± 5 mmHg; mean pulmonary artery pressure 24 ± 4 mmHg vs. 37 ± 8 mmHg; right atrial pressure 8 ± 4 mmHg vs. 15 ± 4 mmHg; LV dP/dtmax 1515 ± 391 mmHg·s−1 vs. 879 ± 333 mmHg−s−1; LV dP/dtmin −2116 ± 569 mmHg·s−1 vs. −1138 ± 545 mmHg·s−1; p ≤ 0.03 for all comparisons). These findings were supported by gross pathological observations and there was a survival advantage with shunting (13/14 vs. 4/7 at 12 weeks, p = 0.047). Shunts were small with Qp:Qs 1.2 ± 0.1 and all devices were patent at necropsy. Conclusion: In an animal model of ischemic cardiomyopathy, interatrial shunting selectively unloaded the left-heart leading to sustained reductions in left-atrial pressure, improved left ventricular performance, preserved inotropic and lusitropic function with blunted remodeling. Secondary pulmonary hypertension was absent and right-sided cardiac pressures and function were preserved.