A Risk Management Strategy for Managing Critical Human Resource Changes in a Pediatric Heart Program.

BACKGROUND: Relocation, recruitment, or retirement of critical team members may lead to changes in the expertise pool that could threaten patient outcomes in a pediatric heart program. We developed a quality initiative aimed at risk management that uses risk-stratified case complexity and outcomes to guide a program during critical fluxes in the expert staff. The Ramp Down/Up protocol is a systematic, voluntary reduction in the complexity of cases performed, followed by a transparent and intentional escalation of case complexity. METHODS: Institutional Ethics Review Board approval for this quality initiative was obtained. Patient/caregiver consent for quality data collection is obtained at the time of hospital admission. Every surgical patient having their index cardiac surgical procedure at the Izaak Walton Killam (IWK) from January 1, 2003, to December 2015 is included. The Ramp Down/Up protocol evolved to have to 4 critical elements: (1) a trigger and a reduction in case complexity; (2) an external/objective expert observer; (3) an escalation in case complexity; and (4) data (qualitative and quantitative) collection and analysis. RESULTS: The Ramp Down/Up protocol was used 3 times over a 12-year period to address critical expert human resource challenges. The protocol was used for variable duration (3.5-9 months). Patient operative mortality was benchmarked to the Congenital Cardiac Surgery database, and outcomes were stable during and after protocol employment. CONCLUSIONS: A quality initiative aimed at risk management has allowed 1 pediatric heart team to ensure that patient outcomes were maintained during critical human resource changes.

CONTEXTE: La relocalisation, le recrutement ou le départ à la retraite de membres critiques d'une équipe peuvent amener des changements dans le bassin d'expertises pouvant compromettre les résultats obtenus par les patients au sein d'un programme de pédiatrie cardiaque. Nous avons conçu une initiative relative à la qualité de la gestion des risques, qui évalue la complexité des cas et les résultats, stratifiés selon le risque, afin d'orienter le programme durant les flux critiques de personnel spécialisé. Le protocole de réduction/d'augmentation réalise une diminution méthodique et délibérée de la complexité des cas suivie d'une intensification transparente et intentionnelle de celle-ci. MÉTHODOLOGIE: Cette initiative sur la qualité a obtenu l'approbation du comité d'examen de l'éthique des établissements. Le consentement du patient/de l'aidant requis pour la collecte de données sur la qualité est obtenu au moment de l'admission à l'hôpital. L'initiative incluait tous les patients de chirurgie pour lesquels on disposait de l'indice de chirurgie cardiaque établi au centre Izaak Walton Killiam (IWK) entre le 1er janvier 2003 et décembre 2015. Le protocole de réduction/d'augmentation a évolué pour intégrer quatre éléments critiques : 1) un facteur déclencheur et une réduction de la complexité des cas; 2) un observateur externe/expert objectif; 3) une intensification de la complexité des cas; 4) la collecte et l'analyse des données (qualitatives et quantitatives). RÉSULTATS: Le protocole de réduction/d'augmentation a été utilisé à trois reprises sur une période de 12 ans et sur des durées variables (de 3,5 à 9 mois) dans le but de relever des défis majeurs liés aux ressources humaines spécialisées. Les taux de mortalité opératoire des patients ont été comparés à ceux de la base de données sur les chirurgies cardiaques congénitales, et les résultats se sont révélés stables durant et après l'emploi du protocole. CONCLUSIONS: Une initiative sur la qualité ciblant la gestion des risques a permis à une équipe de pédiatrie cardiaque de s'assurer que les patients continuaient d'obtenir des résultats similaires lors de changements critiques des ressources humaines.

Protecting the aged heart during cardiac surgery: single-dose del Nido cardioplegia is superior to multi-dose del Nido cardioplegia in isolated rat hearts.

BACKGROUND: Aged hearts are particularly vulnerable to reperfusion injury. We recently showed that single-dose del Nido cardioplegia was superior to 'standard' multi-dose 4:1 blood cardioplegia in aged rat hearts. This study seeks to determine if multi-dose del Nido cardioplegia offers additional benefits over single-dose del Nido cardioplegia. METHODS: Functional recovery after 60 min of cardioplegic arrest was assessed in isolated, working, senescent rat hearts. Single-dose del Nido cardioplegia (n=14) was compared to multi-dose del Nido cardioplegia (n=12) delivered every 20 min. RESULTS: Troponin release during reperfusion was similar in the single (0.263 ± 0.056 ng/ml) and multi-dose groups (0.261 ± 0.055 ng/ml). Although functional recovery was similar early after reperfusion (stroke work 91 ± 6 ml*mmHg*g(-1) vs. 91 ± 8 ml*mmHg*g(-1) for single- vs. multi-dose), it declined over time in the multi-dose group (71 ± 9 vs. 43 ± 9 ml*mmHg*g(-1) at 60 min, p=0.0175) CONCLUSIONS: In aged rat hearts, a single-dose del Nido cardioplegia strategy results in superior functional recovery compared to a multi-dose del Nido cardioplegia strategy.

Effects of Wild-Type and Mutant Forms of Atrial Natriuretic Peptide on Atrial Electrophysiology and Arrhythmogenesis.

BACKGROUND: Atrial natriuretic peptide (ANP) is a hormone with numerous beneficial cardiovascular effects. Recently, a mutation in the ANP gene, which results in the generation of a mutant form of ANP (mANP), was identified and shown to cause atrial fibrillation in people. The mechanism(s) through which mANP causes atrial fibrillation is unknown. Our objective was to compare the effects of wild-type ANP and mANP on atrial electrophysiology in mice and humans. METHODS AND RESULTS: Action potentials (APs), L-type Ca(2+) currents (ICa,L), and Na(+) current were recorded in atrial myocytes from wild-type or natriuretic peptide receptor C knockout (NPR-C(-/-)) mice. In mice, ANP and mANP (10-100 nmol/L) had opposing effects on atrial myocyte AP morphology and ICa,L. ANP increased AP upstroke velocity (Vmax), AP duration, and ICa,L similarly in wild-type and NPR-C(-/-) myocytes. In contrast, mANP decreased Vmax, AP duration, and ICa,L, and these effects were completely absent in NPR-C(-/-) myocytes. ANP and mANP also had opposing effects on ICa,L in human atrial myocytes. In contrast, neither ANP nor mANP had any effect on Na(+) current in mouse atrial myocytes. Optical mapping studies in mice demonstrate that ANP sped electric conduction in the atria, whereas mANP did the opposite and slowed atrial conduction. Atrial pacing in the presence of mANP induced arrhythmias in 62.5% of hearts, whereas treatment with ANP completely prevented the occurrence of arrhythmias. CONCLUSIONS: These findings provide mechanistic insight into how mANP causes atrial fibrillation and demonstrate that wild-type ANP is antiarrhythmic.

Protecting the aged heart during cardiac surgery: use of del Nido cardioplegia provides superior functional recovery in isolated hearts.

OBJECTIVES: Aged hearts are particularly vulnerable to ischemia-reperfusion injury. Our objective was to determine if del Nido cardioplegia, which contains lidocaine, less blood, and less calcium than our standard cardioplegia, provides superior protection for aged hearts. We also sought to determine if the lidocaine in del Nido cardioplegia is adequate to prevent Na(+) influx via the window current. METHODS: Sodium channel kinetics were measured in rat cardiomyocytes with and without lidocaine. Recovery after 60 minutes of cardioplegic arrest was assessed in isolated working senescent rat hearts. Del Nido cardioplegia was delivered as a single dose (n = 8) because it is used clinically, and standard cardioplegia was delivered as an induction dose with re-dosing every 20 minutes (n = 8). After 20 minutes of reperfusion, hearts were switched to working mode for 60 minutes. Flows were indexed to ventricular dry weight. Troponin release was assayed. RESULTS: Sodium channel kinetics indicated that the lidocaine concentration in del Nido cardioplegia minimizes the potential for Na+ influx via the window current. Spontaneous contractions occurred in fewer hearts arrested with del Nido cardioplegia (88% vs 13%; P = .01), and troponin release was reduced (0.24 vs 0.89 ng/mL; P = .017). Cardiac output was approximately 90% of baseline in the del Nido group compared with approximately 50% in the standard group (173 ± 14 vs 86 ± 22 mL · min(-1) · g(-1); P = .0008). Stroke work was higher in the del Nido group (93 ± 6 vs 41 ± 10 mL · mm Hg · g(-1); P = .0002). CONCLUSIONS: Del Nido cardioplegia prevents spontaneous contractions during arrest, reduces troponin release, and results in superior myocardial function in isolated aged hearts. Del Nido cardioplegia has the potential to provide superior myocardial protection for older patients undergoing cardiac surgery.

Impact of hepatocyte growth factor on skeletal myoblast transplantation late after myocardial infarction.

In clinical studies, skeletal myoblast (SKMB) transplantation late after myocardial infarction (MI) has minimal impact on left ventricular (LV) function. This may be related to our previous observation that the extent of SKMB engraftment is minimal in chronic MI when compared to acute MI, which correlates with decreased hepatocyte growth factor (HGF) expression, an important regulator of SKMB function. Here, we investigated delivery of exogenous HGF as a strategy for augmenting SKMB engraftment late after MI. Rats underwent SKMB transplantation 4 weeks after coronary ligation. HGF or vehicle control was delivered intravenously during the subsequent 2 weeks. LV function was assessed by MRI before and 2 weeks after SKMB transplantation. We evaluated HGF delivery, SKMB engraftment, and expression of genes associated with post-MI remodeling. Serum HGF was 6.2 ± 2.4 ng/mL after 2 weeks of HGF infusion (n = 7), but undetectable in controls (n = 7). LV end-diastolic volume and ejection fraction did not improve with HGF treatment (321 ± 27 mm(3), 42% ± 2% vs. 285 ± 33 mm(3), 43% ± 2%, HGF vs. control). MIs were larger in HGF-treated animals (50 ± 7 vs. 30 ± 6 mm(3), P = 0.046), but the volume of engrafted SKMBs or percentage of MIs occupied by SKMBs did not increase with HGF (1.7 ± 0.3 mm(3), 4.7% ± 1.9% vs. 1.4 ± 0.4 mm(3), 5.3% ± 1.6%, HGF vs. control). Expression of genes associated with post-infarction remodeling was not altered by HGF. Delivery of exogenous HGF failed to augment SKMB engraftment and functional recovery in chronic MI. Expression of genes associated with LV remodeling was not altered by HGF. Alternative strategies to enhance engraftment of SKMB must be explored to optimize the clinical efficacy of SKMB transplantation.

Real-time complication monitoring in pediatric cardiac surgery.

BACKGROUND: As overall mortality rates have fallen in pediatric cardiac surgical procedures, complication monitoring is becoming an increasingly important metric of patient outcome. Currently there is no standardized method available to monitor severity-adjusted complications in congenital cardiac surgical procedures. METHODS: Complications associated with pediatric cardiac surgical procedures were prospectively collected from consecutive cases in a single pediatric cardiac surgical unit from October 1, 2009 to September 31, 2011. Complications were accounted for by frequency and severity and then stratified by surgical complexity, using the Risk Adjustment for Congenital Heart Surgery (RACHS) method, giving an average morbidity burden per RACHS category. "Expected" morbidity burden for each RACHS category was derived from year 1 (2009-2010) data. Observed minus expected (O:E) plots were then generated for the entire series of complications from year 2 (2010-2011) data. Separate O:E plots were also created for 5 complication classes and monitored for increases. RESULTS: There were 181 index surgical procedures performed in 178 patients. Two hundred and seventeen complications occurred in 80 procedures. The frequency and severity of complications increased with surgical complexity. The overall O:E plot was flagged twice for unanticipated increases in severity-adjusted complications. When the class-specific O:E plots were monitored for increases, the overall flags were found to originate from increased rates of infections and cardiac/operative complications. CONCLUSIONS: The O:E plot provides a simple and effective system to monitor complication rates over time based on severity-adjusted complication data. Grouping complications into classes allows us to identify specific subsets of complications that can be focused on to improve patient outcomes.

Improving and standardizing capture of pediatric cardiac surgical complications.

OBJECTIVE: Our objective was to establish baseline data and develop a tool to allow for systematic evaluation of pediatric cardiac surgical complications. As a first step, we examined the incidence and distribution of complications, risk stratified by case complexity in a single institution. With improving mortality rates for congenital heart surgery, the next frontier for improving patient outcomes is characterizing and reducing complications. Currently, no standardized approach is available to monitor the incidence and severity of all complications associated with a congenital cardiac surgery program. METHODS: Complications occurring in pediatric cardiac surgical patients (January 2006 to March 2009) were collected by database review applying standardized definitions. The surgical procedures were stratified by complexity to analyze the distribution of complications over the risk spectrum. Each complication was assigned a severity coefficient (1-3) used to calculate the combined effect of frequency and severity. The cumulative sum method was used to determined the trend of the adverse outcomes. RESULTS: Of 292 procedures, 84 (28.8%) were associated with a total of 150 complications. Of the 150 complications, 37 occurred in patients who died. The most common complications were arrhythmias (14.5%), cardiac (12.6%), and operative (12.6%). There was a linear relationship between the frequency and severity of complications and surgical complexity, as stratified using the Risk Adjustment for Congenital Heart Surgery category or Aristotle basic complexity levels (Spearman's coefficient = 1). CONCLUSIONS: When examined in a systematic fashion, the risk of complications in pediatric cardiac surgical patients is considerable. Our data illustrate that it is possible to track complications over time in a consistent manner. The effect of complication monitoring on patient outcomes remains to be proved.

Protecting the aged heart during cardiac surgery: the potential benefits of del Nido cardioplegia.

OBJECTIVE: Aged hearts are more vulnerable than mature hearts to reperfusion injury during cardiac surgery because of altered cardiomyocyte Ca(2+) homeostasis. Inasmuch as immature cardiomyocytes have similar properties, a specialized cardioplegic solution (del Nido cardioplegia) designed to protect children's hearts may also be beneficial for elderly patients. Our objective was to evaluate the ability of del Nido cardioplegic solution, containing lidocaine and less Ca(2+) than our standard cardioplegic solution, to protect aged cardiomyocytes during cardioplegic arrest and reperfusion. METHODS: We used our novel isolated cell model of cardioplegic arrest and reperfusion to compare the effect of del Nido cardioplegic solution with that of our standard cardioplegic solution on intracellular Ca(2+) concentration, contractions, and membrane potential in cardiomyocytes from senescent rat hearts. RESULTS: The incidence of spontaneous contractions during cardioplegic arrest was lower with del Nido cardioplegia (3/11 vs 9/11 cells; P < .05) than with standard cardioplegia, and contractions could not be induced by field stimulation of cardiomyocytes arrested with del Nido cardioplegia (0/11 vs 9/11 cells; P < .05). Intracellular diastolic Ca(2+) levels were lower during arrest with del Nido cardioplegia (57.10 ± 3.06 vs 76.19 ± 3.45 nmol/L; P < .05). During early reperfusion, a potentially injurious rapid recovery of intracellular Ca(2+) associated with hypercontraction in cardiomyocytes arrested with standard cardioplegic solution was avoided in cells treated with del Nido cardioplegia (81.42 ± 2.99 vs 103.15 ± 4.25 nM; P < .05). CONCLUSIONS: Del Nido cardioplegic solution has the potential to provide superior myocardial protection in senescent hearts by preventing electromechanical activity during cardioplegic arrest and Ca(2+)-induced hypercontraction during early reperfusion.

Engraftment is optimal when myoblasts are transplanted early: the role of hepatocyte growth factor.

BACKGROUND: In a recent clinical trial, skeletal myoblast (SKMB) transplantation performed late after myocardial infarction (MI) did not improve left ventricular function. We hypothesized that (1) delaying SKMB transplantation until a chronic infarct scar has developed reduces engraftment, and (2) hepatocyte growth factor (HGF), a main regulator of SKMBs, is present in acute but not chronic MI, potentially influencing engraftment. METHODS: Rats underwent coronary artery ligation followed by SKMB transplantation immediately (n = 12) or delayed by 5 weeks (n = 11). The volume of engrafted SKMBs was quantified 6 weeks later. Hepatocyte growth factor was evaluated by computerized analysis of immunohistochemical labeling of rat heart sections 48 hours, 1 week, 2 weeks, and 5 weeks after coronary artery ligation. The impact of HGF on SKMB proliferation and its ability to protect against oxidative stress and hypoxia was evaluated in vitro. RESULTS: Skeletal myoblast transplantation immediately after MI resulted in an engraftment volume of 29.1 +/- 2.9 mm(3). However, delaying SKMB transplantation 5 weeks caused a 95% drop in engraftment (1.4 +/- 0.3 mm(3); p < 0.001). Hepatocyte growth factor labeling in MIs 48 hours after coronary artery ligation was similar to control myocardium (18.0 +/- 2.0 versus 16.8 +/- 1.3 units). However, HGF declined progressively at 1, 2, and 5 weeks after MI (9.1 +/- 1.4, 4.2 +/- 0.4, and 3.1 +/- 0.6 units, respectively; p < 0.05 versus 48 hours). Hepatocyte growth factor caused a dose-dependent increase in SKMB proliferation in vitro and protected against oxidative stress and hypoxia. CONCLUSIONS: These results demonstrate that engraftment of SKMBs is impaired when transplantation is delayed until a chronic infarct has developed. Hepatocyte growth factor in MI declines with time and may enhance engraftment of SKMBs transplanted early after MI. Delivery of exogenous HGF to enhance SKMB engraftment in chronic infarcts warrants further investigation.

Low molecular weight heparin and unfractionated heparin are both effective at accelerating pulmonary vascular maturation in neonatal rabbits.

BACKGROUND: Creation of a bi-directional cavopulmonary shunt after the Norwood procedure for hypoplastic left heart syndrome is delayed to allow pulmonary vascular resistance to fall with maturation of the pulmonary vascular bed. We hypothesized that unfractionated heparin (UFH) and low molecular weight heparin (LMWH), which promote angiogenesis and inhibit smooth muscle cell growth, could accelerate this process. METHODS AND RESULTS: Fifty-six newborn rabbits were randomly selected to receive UFH 225U/kg (n=12), LMWH 1 mg/kg (n=14), LMWH 10 mg/kg (n=16), or saline (n=14) by subcutaneous injection every 12 hours for 14 days. Treatment with heparin reduced mean pulmonary artery (PA) pressure by 12% to 16% relative to controls [9.0+/-0.2 (UFH), 9.4+/-0.1 (LMWH 1 mg/kg), 9.2+/-0.2 (LMWH 10 mg/kg) versus 10.7+/-0.2 mm Hg (saline), P=0.0001]. Lower PA pressures were associated with reduced alveolar:arterial ratio consistent with enhanced pulmonary angiogenesis in heparin treated animals [8+/-1 (UFH), 13+/-2 (LMWH 1 mg/kg), 12+/-2 (LMWH 10 mg/kg) versus 23+/-5 (saline), P<0.03]. Reduced PA medial wall thickness and muscularization, two additional features of pulmonary vascular maturation, were also more evident in heparin treated animals. Mean PA pressures in 14-day-old rabbits treated with heparin were lower than those measured in control rabbits less than 7 weeks of age suggesting that heparin shortens the pulmonary vascular maturation process by over 60%. CONCLUSIONS: These results indicate that both UFH and LMWH are effective at accelerating pulmonary vascular maturation in newborn rabbits. This raises the possibility that administration of heparin to children after the Norwood procedure might allow for earlier conversion to a bi-directional cavopulmonary shunt.

Aortic root replacement with anomalous origin of the coronary arteries.

Coronary arteries with anomalous origin from the aorta can be at risk during aortic valve procedures. We report a case of origin of the circumflex and left coronary artery from the proximal right coronary artery in a patient with a bicuspid aortic valve and aortic root aneurysm. Attention to the anatomic relationship of the anomalous arteries to the aorta allowed safe aortic root replacement.