SCC3 is an axial element essential for homologous chromosome pairing and synapsis.

Cohesin is a multi-subunit protein that plays a pivotal role in holding sister chromatids together during cell division. Sister chromatid cohesion 3 (SCC3), constituents of cohesin complex, is highly conserved from yeast to mammals. Since the deletion of individual cohesin subunit always causes lethality, it is difficult to dissect its biological function in both mitosis and meiosis. Here, we obtained scc3 weak mutants using CRISPR-Cas9 system to explore its function during rice mitosis and meiosis. The scc3 weak mutants displayed obvious vegetative defects and complete sterility, underscoring the essential roles of SCC3 in both mitosis and meiosis. SCC3 is localized on chromatin from interphase to prometaphase in mitosis. However, in meiosis, SCC3 acts as an axial element during early prophase I and subsequently situates onto centromeric regions following the disassembly of the synaptonemal complex. The loading of SCC3 onto meiotic chromosomes depends on REC8. scc3 shows severe defects in homologous pairing and synapsis. Consequently, SCC3 functions as an axial element that is essential for maintaining homologous chromosome pairing and synapsis during meiosis.

RETINOBLASTOMA RELATED 1 switches mitosis to meiosis in rice.

The transition from mitosis to meiosis is a critical event in the reproductive development of all sexually reproducing species. However, the mechanisms that regulate this process in plants remain largely unknown. Here, we find that the rice (Oryza sativa L.) protein RETINOBLASTOMA RELATED 1 (RBR1) is essential to the transition from mitosis to meiosis. Loss of RBR1 function results in hyper-proliferative sporogenous-cell-like cells (SCLs) in the anther locules during early stages of reproductive development. These hyper-proliferative SCLs are unable to initiate meiosis, eventually stagnating and degrading at late developmental stages to form pollen-free anthers. These results suggest that RBR1 acts as a gatekeeper of entry into meiosis. Furthermore, cytokinin content is significantly increased in rbr1 mutants, whereas the expression of type-B response factors, particularly LEPTO1, is significantly reduced. Given the known close association of cytokinins with cell proliferation, these findings imply that hyper-proliferative germ cells in the anther locules may be attributed to elevated cytokinin concentrations and disruptions in the cytokinin pathway. Using a genetic strategy, the association between germ cell hyper-proliferation and disturbed cytokinin signaling in rbr1 has been confirmed. In summary, we reveal a unique role of RBR1 in the initiation of meiosis; our results clearly demonstrate that the RBR1 regulatory module is connected to the cytokinin signaling pathway and switches mitosis to meiosis in rice.

FANCM interacts with the MHF1-MHF2 complex to limit crossover frequency during rice meiosis.

Crossovers (COs) are necessary for generating genetic diversity that breeders can select, but there are conserved mechanisms that regulate their frequency and distribution. Increasing CO frequency may raise the efficiency of selection by increasing the chance of integrating more desirable traits. In this study, we characterize rice FANCM and explore its functions in meiotic CO control. FANCM mutations do not affect fertility in rice, but they cause a great boost in the overall frequency of COs in both inbred and hybrid rice, according to genetic analysis of the complete set of fancm zmm (hei10, ptd, shoc1, mer3, zip4, msh4, msh5, and heip1) mutants. Although the early homologous recombination events proceed normally in fancm, the meiotic extra COs are not marked with HEI10 and require MUS81 resolvase for resolution. FANCM depends on PAIR1, COM1, DMC1, and HUS1 to perform its functions. Simultaneous disruption of FANCM and MEICA1 synergistically increases CO frequency, but it is accompanied by nonhomologous chromosome associations and fragmentations. FANCM interacts with the MHF complex, and ablation of rice MHF1 or MHF2 could restore the formation of 12 bivalents in the absence of the ZMM gene ZIP4. Our data indicate that unleashing meiotic COs by mutating any member of the FANCM-MHF complex could be an effective procedure to accelerate the efficiency of rice breeding.

RAD51C-RAD51D interplays with MSH5 and regulates crossover maturation in rice meiosis.

Meiotic crossovers ensure accurate chromosome segregation and increase genetic diversity. RAD51C and RAD51D play an early role in facilitating RAD51 during homologous recombination. However, their later function in meiosis is largely unknown in plants. Here, through targeted disruption of RAD51C and RAD51D, we generated three new mutants and revealed their later meiotic role in crossover maturation. The rad51c-3 and rad51d-4 mutants showed a mixture of bivalents and univalents and no chromosomal entanglements, whereas rad51d-5 exhibited an intermediate phenotype with reduced chromosomal entanglements and increased bivalent formation compared with knockout alleles. Comparisons of RAD51 loadings and chromosomal entanglements in these single mutants, rad51c-3 rad51d-4, rad51c-3 dmc1a dmc1b, and rad51d-4 dmc1a dmc1b suggest that the retained level of RAD51 in mutants is required for uncovering their function in crossover formation. Reductions in chiasma frequency and later HEI10 foci in these mutants support that crossover maturation requires RAD51C and RAD51D. Moreover, interaction between RAD51D and MSH5 indicates that RAD51 paralogs may cooperate with MSH5 to ensure accurate Holliday junction processing into crossover products. This finding of the role of RAD51 paralogs in crossover control may be conserved from mammals to plants and advances our current understanding of these proteins.

Replication protein A large subunit (RPA1a) limits chiasma formation during rice meiosis.

Replication protein A (RPA), a single-stranded DNA-binding protein, plays essential role in homologous recombination. However, because deletion of RPA causes embryonic lethality in mammals, the exact function of RPA in meiosis remains unclear. In this study, we generated an rpa1a mutant using CRISPR/Cas9 technology and explored its function in rice (Oryza sativa) meiosis. In rpa1a, 12 bivalents were formed at metaphase I, just like in wild-type, but chromosome fragmentations were consistently observed at anaphase I. Fluorescence in situ hybridization assays indicated that these fragmentations were due to the failure of the recombination intermediates to resolve. Importantly, the mutant had a highly elevated chiasma number, and loss of RPA1a could completely restore the 12 bivalent formations in the zmm (for ZIP1-4, MSH4/5, and MER3) mutant background. Protein-protein interaction assays showed that RPA1a formed a complex with the methyl methansulfonate and UV sensitive 81 (and the Fanconi anemia complementation group M-Bloom syndrome protein homologs (RECQ4A)-Topoisomerase3α-RecQ-mediated genome instability 1 complex to regulate chiasma formation and processing of the recombination intermediates. Thus, our data establish a pivotal role for RPA1a in promoting the accurate resolution of recombination intermediates and in limiting redundant chiasma formation during rice meiosis.

PRD1, a homologous recombination initiation factor, is involved in spindle assembly in rice meiosis.

The bipolar spindle structure in meiosis is essential for faithful chromosome segregation. PUTATIVE RECOMBINATION INITIATION DEFECT 1 (PRD1) previously has been shown to participate in the formation of DNA double strand breaks (DSBs). However, the role of PRD1 in meiotic spindle assembly has not been elucidated. Here, we reveal by both genetic analysis and immunostaining technology that PRD1 is involved in spindle assembly in rice (Oryza sativa) meiosis. We show that DSB formation and bipolar spindle assembly are disturbed in prd1 meiocytes. PRD1 signals display a dynamic pattern of localization from covering entire chromosomes at leptotene to congregating at the centromere region after leptotene. Centromeric localization of PRD1 signals depends on the organization of leptotene chromosomes, but not on DSB formation and axis establishment. PRD1 exhibits interaction and co-localization with several kinetochore components. We also find that bi-orientation of sister kinetochores within a univalent induced by mutation of REC8 can restore bipolarity in prd1. Furthermore, PRD1 directly interacts with REC8 and SGO1, suggesting that PRD1 may play a role in regulating the orientation of sister kinetochores. Taken together, we speculate that PRD1 promotes bipolar spindle assembly, presumably by modulating the orientation of sister kinetochores in rice meiosis.

OsMTOPVIB is required for meiotic bipolar spindle assembly.

The organization of microtubules into a bipolar spindle is essential for chromosome segregation. Both centrosome and chromatin-dependent spindle assembly mechanisms are well studied in mouse, Drosophila melanogaster, and Xenopus oocytes; however, the mechanism of bipolar spindle assembly in plant meiosis remains elusive. According to our observations of microtubule assembly in Oryza sativa, Zea mays, Arabidopsis thaliana, and Solanum lycopersicum, we propose that a key step of plant bipolar spindle assembly is the correction of the multipolar spindle into a bipolar spindle at metaphase I. The multipolar spindles failed to transition into bipolar ones in OsmtopVIB with the defect in double-strand break (DSB) formation. However, bipolar spindles were normally assembled in several other mutants lacking DSB formation, such as Osspo11-1, pair2, and crc1, indicating that bipolar spindle assembly is independent of DSB formation. We further revealed that the mono-orientation of sister kinetochores was prevalent in OsmtopVIB, whereas biorientation of sister kinetochores was frequently observed in Osspo11-1, pair2, and crc1 In addition, mutations of the cohesion subunit OsREC8 resulted in biorientation of sister kinetochores as well as bipolar spindles even in the background of OsmtopVIB Therefore, we propose that biorientation of the kinetochore is required for bipolar spindle assembly in the absence of homologous recombination.

Perception scores of siblings and parents of children with hypoplastic left heart syndrome.

OBJECTIVES: Siblings of children with chronic medical conditions endorse a lower quality of life compared to age-matched peers. Caregiver and sibling-self report of adjustment are often discordant. Congenital heart disease significantly affects family life. To date, there have been no studies addressing the functioning of siblings of children with hypoplastic left heart syndrome, one of the most severe forms of congenital heart disease. The goal of this study was to assess the impact of hypoplastic left heart syndrome on sibling's quality of life as well as the caregiver's perception of this effect. STUDY DESIGN: Cross-sectional study using a web-based survey distributed via various listservs targeted towards families of children with hypoplastic left heart syndrome. Employed the Sibling Perception Questionnaire, designed to assess sibling and caregiver perceptions of adjustment to chronic illness. A Negative Adjustment Composite Score was calculated for each respondent, with higher values representing more negative adjustment. RESULTS: Thirty-five caregivers responded. Majority of caregivers were female (74%), white (86%) and college educated (54%). Thirty-two siblings participated, ranging in age from 7 to 30 years of age (12.5 ± 6.3). Most children with hypoplastic left heart syndrome (73%) had undergone the third stage of palliation. Forty-two caregiver-sibling pairs were examined. Caregiver Negative Adjustment Composite Scores were significantly higher than sibling scores, with caregivers reporting more adjustment problems (2.4 ± 0.4) than siblings (2.3 ± 0.3, P < .05). Sibling age was correlated with worse caregiver and sibling scores (r 0.35, P < .05). CONCLUSIONS: Caregivers of children with hypoplastic left heart syndrome perceive their siblings as struggling more than the children self-report. Siblings tend to report worse adjustment as they get older. These data suggest that programs should include support for the entire family through all ages to optimize quality of life.

Echocardiographic right ventricular function correlations with cardiac catheterisation data in biventricular congenital heart patients.

BACKGROUND: Newer echocardiographic techniques may allow for more accurate assessment of right ventricular function. Adult studies have correlated these echocardiographic measurements with invasive data, but minimal data exist in the paediatric congenital heart population. The purpose of this study was to evaluate echocardiographic measurements that correlate best with right ventricular systolic and diastolic catheterisation parameters. METHODS: Patients with two-ventricle physiology who underwent simultaneous echocardiogram and cardiac catheterisation were included in this study. Right ventricular systolic echocardiographic data included fractional area change, displacement, tissue Doppler imaging s' wave, global longitudinal strain, and strain rate s' wave. Diastolic echocardiographic data included tricuspid E and A waves, tissue Doppler imaging e' and a' waves, and strain rate e' and a' waves. E/tissue Doppler imaging e', tissue Doppler imaging e'/tissue Doppler imaging a', E/strain rate e', and strain rate e'/strain rate a' ratios were also calculated. Catheterisation dP/dt was used as a marker for systolic function and right ventricular end-diastolic pressure for diastolic function. RESULTS: A total of 32 patients were included in this study. The median age at catheterisation was 3.1 years (0.3-17.6 years). The DP/dt was 493±327 mmHg/second, and the right ventricular end-diastolic pressure was 7.7±2.4 mmHg. There were no significant correlations between catheterisation dP/dt and systolic echocardiographic parameters. Right ventricular end-diastolic pressure correlated significantly with strain rate e' (r=-0.4, p=0.02), strain rate a' (r=-0.5, p=0.03), and E/tissue Doppler imaging e' (r=0.4, p=0.04). CONCLUSION: Catheterisation dP/dt did not correlate with echocardiographic measurements of right ventricular systolic function. Strain rate and tissue Doppler imaging analysis significantly correlated with right ventricular end-diastolic pressure. These values should be further studied to determine whether they may be used as an alternative method to estimate right ventricular end-diastolic pressure in this patient population.

Isolated heart transplant and combined heart-liver transplant in adult congenital heart disease patients: Insights from the united network of organ sharing.

BACKGROUND/METHODS: The aging patient with severe congenital heart disease (CHD) faces many challenges: heart failure, arrhythmia, and in the Fontan patient, liver disease. Our goal was to define combined heart liver transplant (CHLT) and isolated orthotopic heart transplant (OHT) outcomes in U.S. adult CHD patients. The U.S. United Network for Organ Sharing (UNOS) thoracic and liver databases were queried for cardiac and CHD diagnoses, from inception-2014. RESULTS: In CHLT, CHD made up 22% of waitlist patients (non-CHD n=262 vs. CHD n=58), and 20% of transplanted patients (non-CHD n=137 vs. CHD n=27). Liver function tests in the non-CHD and CHD groups were similar and there was no difference in CHD and non-CHD survival (HR 0.93, CI: 0.36-2.38, p 0.48). In isolated OHT, CHD patients comprised 2% of those listed (non-CHD n=74,080 vs. CHD n=1599) and transplanted (non-CHD n=48,985 vs. CHD n=967) and had higher early (<1year) mortality (HR 1.36, CI: 1.18-1.57, p<0.0001), but better long-term survival (HR 0.66, CI; 0.57-0.76, p<0.001) than non-CHD. Both groups benefitted from mechanical support when used (non-CHD HR 0.34, CI: 0.31-0.37 and CHD HR 0.14, CI: 0.03-0.58) and prior sternotomy had no effect on mortality in CHD (HR 0.63, CI: 0.15-2.58). CONCLUSIONS: Survival of CHD patients undergoing CHLT is no different than in non-CHD, encouraging consideration of CHLT when clinically appropriate. Short-term mortality is higher in CHD (vs. non-CHD) patients undergoing OHT, regardless of prior cardiac surgery status. Modifications to CHD classification within UNOS would help better understand CHD CHLT and OHT outcomes.

Interstage Survival for Patients with Hypoplastic Left Heart Syndrome After ECMO.

There is a reported 5-20 % incidence of extracorporeal membrane oxygenation (ECMO) following stage I palliation for hypoplastic left heart syndrome (HLHS). This study compares the interstage mortality of HLHS patients supported with ECMO (HLHS-ECMO) to those who were not supported with ECMO (HLHS-nECMO) using the National Pediatric Cardiology Quality Improvement Initiative database. Patients with HLHS who survived to hospital discharge after stage I palliation were analyzed. HLHS-ECMO patients were compared to HLHS-non-ECMO patients with respect to demographics, surgical variables, and interstage survival. A total of 931 patients were identified in the database. Sixty-six (7.1 %) patients were supported with ECMO during their stage I palliation admission. There were no statistically significant differences between the groups with respect to demographics or anatomic subtype. HLHS-ECMO patients were more likely to have a preoperative risk factor identified (62 vs. 48 %, p = 0.03) or require ECMO prior to stage I palliation (3 vs. 0.5 %, p = 0.03). HLHS-ECMO patients had a significantly higher incidence of death or transplant versus the HLHS-nECMO group (18 vs. 9 %, p = 0.03). Despite survival to discharge, patients with HLHS requiring ECMO after their palliation continue to have an increased risk of death/cardiac transplant versus patients that do not require ECMO. ECMO use is likely a marker for a high-risk patient group. These patients may benefit from closer follow-up during the interstage period.

Arrhythmias After Stage I Hybrid Palliation in Single-Ventricle Patients.

The hybrid procedure is an alternative palliative strategy for patients with single-ventricle physiology. No data exist documenting the incidence of arrhythmias after the hybrid procedure. Goal of this study was to determine the incidence and type of arrhythmias in patients undergoing the hybrid procedure. A retrospective chart review was performed including all patients undergoing the hybrid procedure between January of 2010 through December of 2013. Sixty-five patients underwent the hybrid procedure during this time period (43 HLHS, 22 other). Average gestational age at admission was 37.7 weeks. Average age at time of procedure was 7.6 days. Five patients had documented arrhythmias (7.7 %). Four were supraventricular tachycardias, and 1 was a sinus bradycardia. One patient with arrhythmia died during hospitalization, and another patient with arrhythmia died during the interstage period. Hybrid palliation for patients with single-ventricle physiology has a low incidence of arrhythmias. In this cohort of patients, arrhythmias did not contribute to mortality. There was a trend toward association between arrhythmias and longer total length of hospital stay.

Results of a Feeding Protocol in Patients Undergoing the Hybrid Procedure.

Neonates with single-ventricle physiology are at increased risk of developing gastrointestinal morbidities. Feeding protocols in this patient population have been shown to decrease feeding complications after the Norwood procedure, but no data exist to determine the effectiveness of a feeding protocol in patients undergoing the hybrid procedure. Goal of this study was to examine the impact of a standardized feeding protocol on the incidence of overall postoperative gastrointestinal morbidity after the hybrid procedure. Retrospective chart review was performed on neonates undergoing the hybrid procedure. Neonates were divided into two groups, pre-feeding protocol (pre-FP), which encompassed the years 2002-2008, and post-feeding protocol (post-FP), which encompassed the years 2011-2014. Preoperative, operative, and postoperative data were collected. T test or Fisher's exact test was used for analysis. p < 0.05 was considered significant. Seventy-three neonates were in the pre-FP and 52 neonates were in the post-FP. There were no significant differences between the pre-FP and the post-FP in cardiac diagnosis (62 HLHS, 11 other vs. 39 HLHS, 13 other, respectively). Pre-FP underwent hybrid procedure later than the post-FP (9.1 ± 5.8 vs. 5.7 ± 3.4 days, respectively, p < 0.01) and achieved full enteral feeds earlier than the post-FP (3.2 + 2.9 vs. 7.8 + 3.9 days, respectively, p < 0.01). The incidence of necrotizing enterocolitis was higher in the pre-FP versus post-FP [11.0 % (8/65) vs. 5.8 % (3/49), respectively, p = 0.36]. Though not significant, the incidence of necrotizing enterocolitis decreased by almost 50 % after initiating a feeding protocol in patients undergoing the hybrid procedure. This is consistent with previous studies showing beneficial results of a feeding protocol in this complex patient population.

Changes in right ventricular function in neonates with hypoplastic left heart syndrome before and after the hybrid procedure.

AIMS: Decreased right ventricular function via deformation analysis has been noted in patients with hypoplastic left heart syndrome (HLHS) after the Norwood procedure. No data exist in HLHS patients undergoing the hybrid procedure. The goal of this study was to evaluate right ventricular functional changes in HLHS patients undergoing the hybrid procedure under steady-state conditions. METHODS AND RESULTS: Echocardiograms were prospectively obtained on patients with HLHS before and after the hybrid procedure. Fractional area change, tricuspid inflow velocities, tissue Doppler imaging (TDI), and deformation analysis were performed. Paired Wilcoxon's signed rank or Student's t-test was used for analysis. P < 0.05 was considered significant. Twenty HLHS patients were studied (10 males:10 females). Median age at the pre-hybrid echocardiogram was 3 (1-16) days, age at hybrid procedure was 5 (3-17) days, and age at post-hybrid echocardiogram was 10 (6-34). There were significant decreases in systolic function as measured by TDI and deformation analysis. There was no significant change in right ventricular fractional area change. Diastolic function was also noted to significantly decrease after the hybrid procedure. CONCLUSION: Systolic and diastolic functions decreased after the hybrid procedure despite the fact that patients avoided cardiopulmonary bypass. These results are comparable with previous reports in HLHS patients undergoing the Norwood procedure. Further studies are needed to determine if these echocardiographic changes have prognostic significance.

Cost-benefit analysis of robotic versus nonrobotic minimally invasive mitral valve surgery.

OBJECTIVE: To date, a direct comparison of minimally invasive mitral valve repair or replacement (mini-MVR) versus robotic MVR is lacking; therefore, the purpose of this study was to address this deficit and compare mini-MVR with robotic MVR from a cost-benefit perspective. METHODS: From a total of 759 literature citations, 21 studies were included for statistical comparisons of benefit outcomes, whereas 3 studies and our institutional experience were used to compare costs. RESULTS: The total cost per case exceeding that of conventional MVR is approximately $2063.90 for robotic MVR and $271 for mini-MVR. Mean 30-day mortality rates for mini-MVR and robotic MVR groups were 1.24% and 0.55%, respectively [106/8548 vs 6/1089; odds ratio (OR), 2.27; P = 0.052]. The conversion rate to conventional MVR was 0.77% in mini-MVR and 1.83% in robotic MVR (35/5092 vs 22/1046; OR, 0.32; P < 0.001). The rate of neurologic events was 1.32% in mini-MVR and 2.37% in robotic MVR (109/8257 vs 20/845; OR, 0.55; P = 0.02). Postoperative atrial fibrillation was seen in 11.42% of mini-MVR patients and in 19.67% of robotic MVR patients (371/3249 vs 203/1032; OR, 0.53, P < 0.001). Mean cardiopulmonary bypass time was longer in mini-MVR (137.4 vs 130.4 minutes), whereas cross-clamp time was shorter (82.2 vs 96.7 minutes). CONCLUSIONS: Our comparative analysis provides insights into the clinical benefits versus variable costs relationship related to mini-MVR and robotic MVR.

Neurodevelopmental outcome after cardiac surgery utilizing cardiopulmonary bypass in children.

INTRODUCTION: Modulating the stress response and perioperative factors can have a paramount impact on the neurodevelopmental outcome of infants who undergo cardiac surgery utilizing cardiopulmonary bypass. MATERIALS AND METHODS: In this single center prospective follow-up study, we evaluated the impact of three different anesthetic techniques on the neurodevelopmental outcomes of 19 children who previously underwent congenital cardiac surgery within their 1(st) year of life. Cases were done from May 2011 to December 2013. Children were assessed using the Stanford-Binet Intelligence Scales (5(th) edition). Multiple regression analysis was used to test different parental and perioperative factors that could significantly predict the different neurodevelopmental outcomes in the entire cohort of patients. RESULTS: When comparing the three groups regarding the major cognitive scores, a high-dose fentanyl (HDF) patients scored significantly higher than the low-dose fentanyl (LDF) + dexmedetomidine (DEX) (LDF + DEX) group in the quantitative reasoning scores (106 ± 22 vs. 82 ± 15 P = 0.046). The bispectral index (BIS) value at the end of surgery for the -LDF group was significantly higher than that in LDF + DEX group (P = 0.011). For the entire cohort, a strong correlation was seen between the standard verbal intelligence quotient (IQ) score and the baseline adrenocorticotropic hormone level, the interleukin-6 level at the end of surgery and the BIS value at the end of the procedure with an R(2) value of 0.67 and P < 0.04. There was an inverse correlation between the cardiac Intensive Care Unit length of stay and the full-scale IQ score (R = 0.4675 and P 0.027). CONCLUSIONS: Patients in the HDF group demonstrated overall higher neurodevelopmental scores, although it did not reach statistical significance except in fluid reasoning scores. Our results may point to a possible correlation between blunting the stress response and improvement of the neurodevelopmental outcome.

Minimally Invasive Aortic Valve Replacement: Cost-Benefit Analysis of Ministernotomy Versus Minithoracotomy Approach.

BACKGROUND AND AIM OF THE STUDY: Minimally invasive aortic valve replacement via ministernotomy (ministernotomy-AVR) or minithoracotomy (minithoracotomy-AVR) is gaining popularity. To date, a direct comparison of ministernotomy-AVR versus minithoracotomy-AVR is lacking. The study aim was to compare these two procedures from a cost-benefit perspective. METHODS: Eight reports from the United States were selected from amongst 33,494 literature citations based on sample size and data completeness. Perioperative variables were collected for each surgical approach. Fixed and variable costs were estimated as cost per case in excess of full sternotomy AVR procedures. RESULTS: Ministernotomy-AVR patients were of a significantly lower mean age (59.8 years versus 67.9 years), ejection fraction (50.4-51.6% versus 56.1-57.8%), shorter cardiopulmonary bypass time (97.2 min versus 125.6 min) and cross-clamp time (69.9 min versus 87.9 min), a lower rate of blood transfusion (25.9% versus 64.4%), and a shorter length of hospital stay (5.7 versus 6.2 days). There were no significant inter-group differences in 30-day mortality, conversion to sternotomy, neurologic events, arrhythmia, wound infection, or postoperative bleeding. Assuming a volume of 50 cases per year, the added operative cost per case for a minithoracotomy-AVR was US$ 4,254 compared to US$ 290 for a ministernotomy-AVR. The added costs per case, assuming 200 cases per year, were US$ 4,209 and US$ 290, respectively. A minithoracotomy-AVR program performing 50 cases per year adds US$ 1,063,665 of operative costs over five years, compared to US$ 72,500 for a ministernotomy-AVR program. CONCLUSION: The present analysis suggested that the clinical benefits of ministernotomy-AVR are comparable or better than those of minithoracotomy-AVR, and at lower costs. Healthcare delivery organizations should consider the results of cost-benefit examinations when developing surgical valve replacement programs.

Plethysmography variability index response to isovolemic hemodilution in children prior to surgery for congenital heart disease.

The aim of this study was to evaluate the response of pleth variability index (PVI) to phlebotomy in anesthetized children prior to surgery for congenital heart disease. After induction of general anesthesia and prior to surgical incision, approximately 10 mL/kg of blood was removed from 40 mechanically ventilated children over a 5-10 min period. The PVI was continuously monitored. Additionally, the volume of crystalloid required to ensure hemodynamic and near infrared spectroscopy stability was recorded. There was no difference between the pre-phlebotomy PVI (13% ± 6.2) and the post-phlebotomy PVI (16.4% ± 9.6) (P = 0.55). Patients who had a starting PVI ≤14% had a significant increase in PVI after phlebotomy from 9.1% ± 3 to 14.3% ± 7.2 (P = 0.0014). Although, patients with a pre-phlebotomy PVI of >14% required more crystalloid replacement (11 ± 9.4 mL/kg) than those with a PVI ≤14% (5.3 ± 4.7 mL/kg), this was not significant (P = 0.06). In patients who received less crystalloid replacement during phlebotomy, PVI did show a significant increase. Additionally, the data suggests that patients with a pre-phlebotomy PVI >14% required greater fluid replacement than those with a PVI < 14%. Further research is needed to better delineate the utility of PVI in this unique group of patients.