Natural history and outcomes in paediatric RASopathy-associated hypertrophic cardiomyopathy

AIMS

This study aimed to describe the natural history and predictors of all-cause mortality and sudden cardiac death (SCD)/equivalent events in children with a RASopathy syndrome and hypertrophic cardiomyopathy (HCM).

METHODS AND RESULTS

This is a retrospective cohort study from 14 paediatric cardiology centres in the United Kingdom and Ireland. We included children <18 years with HCM and a clinical and/or genetic diagnosis of a RASopathy syndrome [Noonan syndrome (NS), NS with multiple lentigines (NSML), Costello syndrome (CS), cardiofaciocutaneous syndrome (CFCS), and NS with loose anagen hair (NS-LAH)]. One hundred forty-nine patients were recruited [111 (74.5%) NS, 12 (8.05%) NSML, 6 (4.03%) CS, 6 (4.03%) CFCS, 11 (7.4%) Noonan-like syndrome, and 3 (2%) NS-LAH]. NSML patients had higher left ventricular outflow tract (LVOT) gradient values [60 (36-80) mmHg, P = 0.004]. Over a median follow-up of 197.5 [inter-quartile range (IQR) 93.58-370] months, 23 patients (15.43%) died at a median age of 24.1 (IQR 5.6-175.9) months. Survival was 96.45% [95% confidence interval (CI) 91.69-98.51], 90.42% (95% CI 84.04-94.33), and 84.12% (95% CI 75.42-89.94) at 1, 5, and 10 years, respectively, but this varied by RASopathy syndrome. RASopathy syndrome, symptoms at baseline, congestive cardiac failure (CCF), non-sustained ventricular tachycardia (NSVT), and maximal left ventricular wall thickness were identified as predictors of all-cause mortality on univariate analysis, and CCF, NSVT, and LVOT gradient were predictors for SCD or equivalent event.

CONCLUSIONS

These findings highlight a distinct category of patients with Noonan-like syndrome with a milder HCM phenotype but significantly worse survival and identify potential predictors of adverse outcome in patients with RASopathy-related HCM.

COVID-19 in congenital heart disease (COaCHeD) study

BACKGROUND

COVID-19 has caused significant worldwide morbidity and mortality. Congenital heart disease (CHD) is likely to increase vulnerability and understanding the predictors of adverse outcomes is key to optimising care.

OBJECTIVE

Ascertain the impact of COVID-19 on people with CHD and define risk factors for adverse outcomes.

METHODS

Multicentre UK study undertaken 1 March 2020-30 June 2021 during the COVID-19 pandemic. Data were collected on CHD diagnoses, clinical presentation and outcomes. Multivariable logistic regression with multiple imputation was performed to explore predictors of death and hospitalisation.

RESULTS

There were 405 reported cases (127 paediatric/278 adult). In children (age <16 years), there were 5 (3.9%) deaths. Adjusted ORs (AORs) for hospitalisation in children were significantly lower with each ascending year of age (OR 0.85, 95% CI 0.75 to 0.96 (p<0.01)). In adults, there were 24 (8.6%) deaths (19 with comorbidities) and 74 (26.6%) hospital admissions. AORs for death in adults were significantly increased with each year of age (OR 1.05, 95% CI 1.01 to 1.10 (p<0.01)) and with pulmonary arterial hypertension (PAH; OR 5.99, 95% CI 1.34 to 26.91 (p=0.02)). AORs for hospitalisation in adults were significantly higher with each additional year of age (OR 1.03, 95% CI 1.00 to 1.05 (p=0.04)), additional comorbidities (OR 3.23, 95% CI 1.31 to 7.97 (p=0.01)) and genetic disease (OR 2.87, 95% CI 1.04 to 7.94 (p=0.04)).

CONCLUSIONS

Children were at low risk of death and hospitalisation secondary to COVID-19 even with severe CHD, but hospital admission rates were higher in younger children, independent of comorbidity. In adults, higher likelihood of death was associated with increasing age and PAH, and of hospitalisation with age, comorbidities and genetic disease. An individualised approach, based on age and comorbidities, should be taken to COVID-19 management in patients with CHD.

The interplay between pressure, flow, and resistance in neonatal pulmonary hypertension

Pulmonary hypertension, conventionally defined by absolute pulmonary artery pressure, is the result of a range of diagnoses that can result in clinical problems in neonatal practice. Causes include persistent pulmonary hypertension of the newborn, congenital heart disease, and left heart dysfunction, as well as the normally high pulmonary artery resistance in neonates. Elucidating the cause of pulmonary hypertension is vital to guide appropriate management. A first principles approach based on hemodynamic calculations provides a framework for the diagnostic work up and subsequent therapy. Central to this is the equation 'pressure = flow x resistance' and knowledge of factors contributing to flow and resistance and their impact on pulmonary artery pressure. While formal, accurate, calculation of each element is usually not required or deliverable in small infants, clinical and echocardiographic parameters, combined with an understanding of the interplay between pressure, flow, and resistance, significantly improves the assessment and management of neonatal pulmonary hemodynamics.

Clinical Features and Natural History of Preadolescent Nonsyndromic Hypertrophic Cardiomyopathy

BACKGROUND

Up to one-half of childhood sarcomeric hypertrophic cardiomyopathy (HCM) presents before the age of 12 years, but this patient group has not been systematically characterized.

OBJECTIVES

The aim of this study was to describe the clinical presentation and natural history of patients presenting with nonsyndromic HCM before the age of 12 years.

METHODS

Data from the International Paediatric Hypertrophic Cardiomyopathy Consortium on 639 children diagnosed with HCM younger than 12 years were collected and compared with those from 568 children diagnosed between 12 and 16 years.

RESULTS

At baseline, 339 patients (53.6%) had family histories of HCM, 132 (20.9%) had heart failure symptoms, and 250 (39.2%) were prescribed cardiac medications. The median maximal left ventricular wall thickness z-score was 8.7 (IQR: 5.3-14.4), and 145 patients (27.2%) had left ventricular outflow tract obstruction. Over a median follow-up period of 5.6 years (IQR: 2.3-10.0 years), 42 patients (6.6%) died, 21 (3.3%) underwent cardiac transplantation, and 69 (10.8%) had life-threatening arrhythmic events. Compared with those presenting after 12 years, a higher proportion of younger patients underwent myectomy (10.5% vs 7.2%; P = 0.045), but fewer received primary prevention implantable cardioverter-defibrillators (18.9% vs 30.1%; P = 0.041). The incidence of mortality or life-threatening arrhythmic events did not differ, but events occurred at a younger age.

CONCLUSIONS

Early-onset childhood HCM is associated with a comparable symptom burden and cardiac phenotype as in patients presenting later in childhood. Long-term outcomes including mortality did not differ by age of presentation, but patients presenting at younger than 12 years experienced adverse events at younger ages.

Friedreich's ataxia-associated childhood hypertrophic cardiomyopathy: a national cohort study

OBJECTIVE

Hypertrophic cardiomyopathy (HCM) is an important predictor of long-term outcomes in Friedreich's ataxia (FA), but the clinical spectrum and survival in childhood is poorly described. This study aimed to describe the clinical characteristics of children with FA-HCM.

DESIGN AND SETTING

Retrospective, longitudinal cohort study of children with FA-HCM from the UK.

PATIENTS

78 children (<18 years) with FA-HCM diagnosed over four decades.

INTERVENTION

Anonymised retrospective demographic and clinical data were collected from baseline evaluation and follow-up.

MAIN OUTCOME MEASURES

The primary study end-point was all-cause mortality (sudden cardiac death, atrial arrhythmia-related death, heart failure-related death, non-cardiac death) or cardiac transplantation.

RESULTS

The mean age at diagnosis of FA-HCM was 10.9 (±3.1) years. Diagnosis was within 1 year of cardiac referral in 34 (65.0%) patients, but preceded the diagnosis of FA in 4 (5.3%). At baseline, 65 (90.3%) had concentric left ventricular hypertrophy and 6 (12.5%) had systolic impairment. Over a median follow-up of 5.1 years (IQR 2.4-7.3), 8 (10.5%) had documented supraventricular arrhythmias and 8 (10.5%) died (atrial arrhythmia-related n=2; heart failure-related n=1; non-cardiac n=2; or unknown cause n=3), but there were no sudden cardiac deaths. Freedom from death or transplantation at 10 years was 80.8% (95% CI 62.5 to 90.8).

CONCLUSIONS

This is the largest cohort of childhood FA-HCM reported to date and describes a high prevalence of atrial arrhythmias and impaired systolic function in childhood, suggesting early progression to end-stage disease. Overall mortality is similar to that reported in non-syndromic childhood HCM, but no patients died suddenly.

Relationship Between Maximal Left Ventricular Wall Thickness and Sudden Cardiac Death in Childhood Onset Hypertrophic Cardiomyopathy

BACKGROUND

Maximal left ventricular wall thickness (MLVWT) is a risk factor for sudden cardiac death (SCD) in hypertrophic cardiomyopathy (HCM). In adults, the severity of left ventricular hypertrophy has a nonlinear relationship with SCD, but it is not known whether the same complex relationship is seen in childhood. The aim of this study was to describe the relationship between left ventricular hypertrophy and SCD risk in a large international pediatric HCM cohort.

METHODS

The study cohort comprised 1075 children (mean age, 10.2 years [±4.4]) diagnosed with HCM (1-16 years) from the International Paediatric Hypertrophic Cardiomyopathy Consortium. Anonymized, noninvasive clinical data were collected from baseline evaluation and follow-up, and 5-year estimated SCD risk was calculated (HCM Risk-Kids).

RESULTS

MLVWT Z score was <10 in 598 (58.1%), ≥10 to <20 in 334 (31.1%), and ≥20 in 143 (13.3%). Higher MLVWT Z scores were associated with heart failure symptoms, unexplained syncope, left ventricular outflow tract obstruction, left atrial dilatation, and nonsustained ventricular tachycardia. One hundred twenty-two patients (71.3%) with MLVWT Z score ≥20 had coexisting risk factors for SCD. Over a median follow-up of 4.9 years (interquartile range, 2.3-9.3), 115 (10.7%) had an SCD event. Freedom from SCD event at 5 years for those with MLVWT Z scores <10, ≥10 to <20, and ≥20 was 95.6%, 87.4%, and 86.0, respectively. The estimated SCD risk at 5 years had a nonlinear, inverted U-shaped relationship with MLVWT Z score, peaking at Z score +23. The presence of coexisting risk factors had a summative effect on risk.

CONCLUSIONS

In children with HCM, an inverted U-shaped relationship exists between left ventricular hypertrophy and estimated SCD risk. The presence of additional risk factors has a summative effect on risk. While MLVWT is important for risk stratification, it should not be used either as a binary variable or in isolation to guide implantable cardioverter defibrillator implantation decisions in children with HCM.

Clinical presentation and long-term outcomes of infantile hypertrophic cardiomyopathy: a European multicentre study

AIMS

Children presenting with hypertrophic cardiomyopathy (HCM) in infancy are reported to have a poor prognosis, but this heterogeneous group has not been systematically characterized. This study aimed to describe the aetiology, phenotype, and outcomes of infantile HCM in a well-characterized multicentre European cohort.

METHODS AND RESULTS

Of 301 children diagnosed with infantile HCM between 1987 and 2019 presenting to 17 European centres [male n = 187 (62.1%)], underlying aetiology was non-syndromic (n = 138, 45.6%), RASopathy (n = 101, 33.6%), or inborn error of metabolism (IEM) (n = 49, 16.3%). The most common reasons for presentation were symptoms (n = 77, 29.3%), which were more prevalent in those with syndromic disease (n = 62, 61.4%, P < 0.001), and an isolated murmur (n = 75, 28.5%). One hundred and sixty-one (53.5%) had one or more co-morbidities. Genetic testing was performed in 163 (54.2%) patients, with a disease-causing variant identified in 115 (70.6%). Over median follow-up of 4.1 years, 50 (16.6%) underwent one or more surgical interventions; 15 (5.0%) had an arrhythmic event (6 in the first year of life); and 48 (15.9%) died, with an overall 5 year survival of 85%. Predictors of all-cause mortality were an underlying diagnosis of IEM [hazard ratio (HR) 4.4, P = 0.070], cardiac symptoms (HR 3.2, P = 0.005), and impaired left ventricular systolic function (HR 3.0, P = 0.028).

CONCLUSIONS

This large, multicentre study of infantile HCM describes a complex cohort of patients with a diverse phenotypic spectrum and clinical course. Although overall outcomes were poor, this was largely related to underlying aetiology emphasizing the importance of comprehensive aetiological investigations, including genetic testing, in infantile HCM.

Clinical outcomes and programming strategies of implantable cardioverter-defibrillator devices in paediatric hypertrophic cardiomyopathy: a UK National Cohort Study

AIMS

Sudden cardiac death (SCD) is the most common mode of death in paediatric hypertrophic cardiomyopathy (HCM). This study describes the implant and programming strategies with clinical outcomes following implantable cardioverter-defibrillator (ICD) insertion in a well-characterized national paediatric HCM cohort.

METHODS AND RESULTS

Data from 90 patients undergoing ICD insertion at a median age 13 (±3.5) for primary (n = 67, 74%) or secondary prevention (n = 23, 26%) were collected from a retrospective, longitudinal multi-centre cohort of children (<16 years) with HCM from the UK. Seventy-six (84%) had an endovascular system [14 (18%) dual coil], 3 (3%) epicardial, and 11 (12%) subcutaneous system. Defibrillation threshold (DFT) testing was performed at implant in 68 (76%). Inadequate DFT in four led to implant adjustment in three patients. Over a median follow-up of 54 months (interquartile range 28-111), 25 (28%) patients had 53 appropriate therapies [ICD shock n = 45, anti-tachycardia pacing (ATP) n = 8], incidence rate 4.7 per 100 patient years (95% CI 2.9-7.6). Eight inappropriate therapies occurred in 7 (8%) patients (ICD shock n = 4, ATP n = 4), incidence rate 1.1/100 patient years (95% CI 0.4-2.5). Three patients (3%) died following arrhythmic events, despite a functioning device. Other device complications were seen in 28 patients (31%), including lead-related complications (n = 15) and infection (n = 10). No clinical, device, or programming characteristics predicted time to inappropriate therapy or lead complication.

CONCLUSION

In a large national cohort of paediatric HCM patients with an ICD, device and programming strategies varied widely. No particular strategy was associated with inappropriate therapies, missed/delayed therapies, or lead complications.

Remodeling of the Purkinje Network in Congestive Heart Failure in the Rabbit

Supplemental Digital Content is available in the text.

Background:

Purkinje fibers (PFs) control timing of ventricular conduction and play a key role in arrhythmogenesis in heart failure (HF) patients. We investigated the effects of HF on PFs.

Methods:

Echocardiography, electrocardiography, micro-computed tomography, quantitative polymerase chain reaction, immunohistochemistry, volume electron microscopy, and sharp microelectrode electrophysiology were used.

Results:

Congestive HF was induced in rabbits by left ventricular volume- and pressure-overload producing left ventricular hypertrophy, diminished fractional shortening and ejection fraction, and increased left ventricular dimensions. HF baseline QRS and corrected QT interval were prolonged by 17% and 21% (mean±SEMs: 303±6 ms HF, 249±11 ms control; n=8/7; P=0.0002), suggesting PF dysfunction and impaired ventricular repolarization. Micro-computed tomography imaging showed increased free-running left PF network volume and length in HF. mRNA levels for 40 ion channels, Ca²⁺-handling proteins, connexins, and proinflammatory and fibrosis markers were assessed: 50% and 35% were dysregulated in left and right PFs respectively, whereas only 12.5% and 7.5% changed in left and right ventricular muscle. Funny channels, Ca²⁺-channels, and K⁺-channels were significantly reduced in left PFs. Microelectrode recordings from left PFs revealed more negative resting membrane potential, reduced action potential upstroke velocity, prolonged duration (action potential duration at 90% repolarization: 378±24 ms HF, 249±5 ms control; n=23/38; P<0.0001), and arrhythmic events in HF. Similar electrical remodeling was seen at the left PF-ventricular junction. In the failing left ventricle, upstroke velocity and amplitude were increased, but action potential duration at 90% repolarization was unaffected.

Conclusions:

Severe volume- followed by pressure-overload causes rapidly progressing HF with extensive remodeling of PFs. The PF network is central to both arrhythmogenesis and contractile dysfunction and the pathological remodeling may increase the risk of fatal arrhythmias in HF patients.

The role of the electrocardiographic phenotype in risk stratification for sudden cardiac death in childhood hypertrophic cardiomyopathy

AIMS

The 12-lead electrocardiogram (ECG) is routinely performed in children with hypertrophic cardiomyopathy (HCM). An ECG risk score has been suggested as a useful tool for risk stratification, but this has not been independently validated. This aim of this study was to describe the ECG phenotype of childhood HCM in a large, international, multi-centre cohort and investigate its role in risk prediction for arrhythmic events.

METHODS AND RESULTS

Data from 356 childhood HCM patients with a mean age of 10.1 years (±4.5) were collected from a retrospective, multi-centre international cohort. Three hundred and forty-seven (97.5%) patients had ECG abnormalities at baseline, most commonly repolarization abnormalities (n = 277, 77.8%); left ventricular hypertrophy (n = 240, 67.7%); abnormal QRS axis (n = 126, 35.4%); or QT prolongation (n = 131, 36.8%). Over a median follow-up of 3.9 years (interquartile range 2.0-7.7), 25 (7%) had an arrhythmic event, with an overall annual event rate of 1.38 (95% CI 0.93-2.04). No ECG variables were associated with 5-year arrhythmic event on univariable or multivariable analysis. The ECG risk score threshold of >5 had modest discriminatory ability [C-index 0.60 (95% CI 0.484-0.715)], with corresponding negative and positive predictive values of 96.7% and 6.7.

CONCLUSION

In a large, international, multi-centre cohort of childhood HCM, ECG abnormalities were common and varied. No ECG characteristic, either in isolation or combined in the previously described ECG risk score, was associated with 5-year sudden cardiac death risk. This suggests that the role of baseline ECG phenotype in improving risk stratification in childhood HCM is limited.

COVID-19 in children: what did we learn from the first wave?

A pandemic caused by the novel coronavirus, severe acute respiratory syndrome - coronavirus 2 (SARS-CoV-2), has caused high rates of mortality, predominantly in adults. Children are significantly less affected by SARS-CoV-2 with far lower rates of recorded infections in children compared to adults, milder symptoms in the majority of children and very low mortality rates. A suspected late manifestation of the disease, paediatric inflammatory multisystem syndrome - temporally associated with SARS-CoV-2 (PIMS-TS), has been seen in small numbers of children and has a more severe disease course than acute SARS-CoV-2. The pandemic has meant that children around the world have been kept off school, isolated from their extended family and friends and asked to stay inside. The UK has been declared as being in an economic recession and unemployment rates are increasing. These indirect effects of SARS-CoV-2 are likely to have a significant impact on many children for years to come. Consolidating the knowledge that has accumulated during the first wave of this pandemic is essential for recognising the clinical signs, symptoms and effective treatment strategies for children; identifying children who may be at increased risk of severe SARS-CoV-2 infection; planning the safe delivery of healthcare and non-health related services that are important for childrens' wellbeing; and engaging in, and developing, research to address the things that are not yet known. This article summarises the evidence that has emerged from the early phase of the pandemic and offers an overview for those looking after children or planning services.

A validation study of the European Society of Cardiology guidelines for risk stratification of sudden cardiac death in childhood hypertrophic cardiomyopathy

AIMS

Sudden cardiac death (SCD) is the most common cause of death in children with hypertrophic cardiomyopathy (HCM). The European Society of Cardiology (ESC) recommends consideration of an implantable cardioverter-defibrillator (ICD) if two or more clinical risk factors (RFs) are present, but this approach to risk stratification has not been formally validated.

METHODS AND RESULTS

Four hundred and eleven paediatric HCM patients were assessed for four clinical RFs in accordance with current ESC recommendations: severe left ventricular hypertrophy, unexplained syncope, non-sustained ventricular tachycardia, and family history of SCD. The primary endpoint was a composite outcome of SCD or an equivalent event (aborted cardiac arrest, appropriate ICD therapy, or sustained ventricular tachycardia), defined as a major arrhythmic cardiac event (MACE). Over a follow-up period of 2890 patient years (median 5.5 years), MACE occurred in 21 patients (7.5%) with 0 RFs, 19 (16.8%) with 1 RFs, and 3 (18.8%) with 2 or more RFs. Corresponding incidence rates were 1.13 [95% confidence interval (CI) 0.7-1.73], 2.07 (95% CI 1.25-3.23), and 2.52 (95% CI 0.53-7.35) per 100 patient years at risk. Patients with two or more RFs did not have a higher incidence of MACE (log-rank test P = 0.34), with a positive and negative predictive value of 19% and 90%, respectively. The C-statistic was 0.62 (95% CI 0.52-0.72) at 5 years.

CONCLUSIONS

The incidence of MACE is higher for patients with increasing numbers of clinical RFs. However, the current ESC guidelines have a low ability to discriminate between high- and low-risk individuals.

Clinical presentation and survival of childhood hypertrophic cardiomyopathy: a retrospective study in United Kingdom

Aims

Understanding the spectrum of disease, symptom burden and natural history are essential for the management of children with hypertrophic cardiomyopathy (HCM). The effect of changing screening practices over time has not previously been studied. This study describes the clinical characteristics and outcomes of childhood HCM over four decades in a well-characterized United Kingdom cohort.

Methods and results

Six hundred and eighty-seven patients with HCM presented at a median age of 5.2 years (range 0–16). Aetiology was: non-syndromic (n = 433, 63%), RASopathy (n = 126, 18.3%), Friedreich’s ataxia (n = 59, 8.6%) or inborn errors of metabolism (IEM) (n = 64, 9%). In infants (n = 159, 23%) underlying aetiology was more commonly a RASopathy (42% vs. 11.2%, P < 0.0001) or IEM (18.9% vs. 6.4% P < 0.0001). In those with familial disease, median age of presentation was higher (11 years vs. 6 years, P < 0.0001), 141 (58%) presented <12 years. Freedom from death or transplantation was 90.6% (87.9–92.7%) at 5 years (1.5 per 100 patient years) with no era effect. Mortality was most frequently sudden cardiac death (SCD) (n = 20, 2.9%). Children diagnosed during infancy or with an IEM had a worse prognosis (5-year survival 80.5% or 66.4%). Arrhythmic events occurred at a rate of 1.2 per 100 patient years and were more likely in non-syndromic patients (n = 51, 88%).

Conclusion

This national study describes a heterogeneous disease whose outcomes depend on the age of presentation and aetiology. Overall mortality and SCD rates have not changed over time, but they remain higher than in adults with HCM, with events occurring in syndromic and non-syndromic patients.

Development of a Novel Risk Prediction Model for Sudden Cardiac Death in Childhood Hypertrophic Cardiomyopathy (HCM Risk-Kids)

Importance

Sudden cardiac death (SCD) is the most common mode of death in childhood hypertrophic cardiomyopathy (HCM), but there is no validated algorithm to identify those at highest risk.

Objective

To develop and validate an SCD risk prediction model that provides individualized risk estimates.

Design, Setting, and Participants

A prognostic model was developed from a retrospective, multicenter, longitudinal cohort study of 1024 consecutively evaluated patients aged 16 years or younger with HCM. The study was conducted from January 1, 1970, to December 31, 2017.

Exposures

The model was developed using preselected predictor variables (unexplained syncope, maximal left-ventricular wall thickness, left atrial diameter, left-ventricular outflow tract gradient, and nonsustained ventricular tachycardia) identified from the literature and internally validated using bootstrapping.

Main Outcomes and Measures

A composite outcome of SCD or an equivalent event (aborted cardiac arrest, appropriate implantable cardioverter defibrillator therapy, or sustained ventricular tachycardia associated with hemodynamic compromise).

Results

Of the 1024 patients included in the study, 699 were boys (68.3%); mean (interquartile range [IQR]) age was 11 (7-14) years. Over a median follow-up of 5.3 years (IQR, 2.6-8.3; total patient years, 5984), 89 patients (8.7%) died suddenly or had an equivalent event (annual event rate, 1.49; 95% CI, 1.15-1.92). The pediatric model was developed using preselected variables to predict the risk of SCD. The model's ability to predict risk at 5 years was validated; the C statistic was 0.69 (95% CI, 0.66-0.72), and the calibration slope was 0.98 (95% CI, 0.59-1.38). For every 10 implantable cardioverter defibrillators implanted in patients with 6% or more of a 5-year SCD risk, 1 patient may potentially be saved from SCD at 5 years.

Conclusions and Relevance

This new, validated risk stratification model for SCD in childhood HCM may provide individualized estimates of risk at 5 years using readily obtained clinical risk factors. External validation studies are required to demonstrate the accuracy of this model's predictions in diverse patient populations.

Morphological Substrates for Atrial Arrhythmogenesis in a Heart With Atrioventricular Septal Defect

Due to advances in corrective surgery, congenital heart disease has an ever growing patient population. Atrial arrhythmias are frequently observed pre- and post-surgical correction. Pharmaceutical antiarrhythmic therapy is not always effective, therefore many symptomatic patients undergo catheter ablation therapy. In patients with atrioventricular septal defects (AVSD), ablation therapy itself has mixed success; arrhythmogenic recurrences are common, and because of the anatomical displacement of the atrioventricular node, 3-degree heart block post-ablation is a real concern. In order to develop optimal and safe ablation strategies, the field of congenital cardiac electrophysiology must combine knowledge from clinical electrophysiology with a thorough understanding of the anatomical substrates for arrhythmias. Using image-based analysis and multi-cellular mathematical modeling of electrical activation, we show how the anatomical alterations characteristic of an AVSD serve as arrhythmogenic substrates. Using ex-vivo contrast enhanced micro-computed tomography we imaged post-mortem the heart of a 5 month old male with AVSD at an isometric spatial resolution of 38 μm. Morphological analysis revealed the 3D disposition of the cardiac conduction system for the first time in an intact heart with this human congenital malformation. We observed displacement of the compact atrioventricular node inferiorly to the ostium of the coronary sinus. Myocyte orientation analysis revealed that the normal arrangement of the major atrial muscle bundles was preserved but was modified in the septal region. Models of electrical activation suggest the disposition of the myocytes within the atrial muscle bundles associated with the "fast pathway," together with the displaced atrioventricular node, serve as potential substrates for re-entry and possibly atrial fibrillation. This study used archived human hearts, showing them to be a valuable resource for the mathematical modeling community, and opening new possibilities for the investigations of arrhythmogenesis and ablation strategies in the congenitally malformed heart.

Effect of Prenatal Laterality Disturbance and Its Accompanying Anomalies on Survival

In this retrospective, observational study of fetuses diagnosed with a laterality disturbance we describe the findings and outcome of fetuses diagnosed between 1980 and 2017 at a tertiary fetal-pediatric cardiology unit. In addition we sought to identify features which impact on outcome. Left atrial isomerism (LAI) was diagnosed in 177 babies and right atrial isomerism (RAI) in 100. Major structural heart disease was present in all cases of RAI and 91% with LAI. Complete heart block (CHB) was present in 40% of LAI. For surviving live-born infants a biventricular circulation was feasible in 3% with RAI and 43% with LAI. The median survival for live-borns with LAI was 13 months (range 0 to 272 months) and for RAI 19 months (range 0.3 to 292 months). The median postnatal survival with CHB was 0.2 months (range 0 to 228 months) compared to 44 months with sinus rhythm (interquartile range 0 to 272 months; p <0.0001). The 5-year survival was 1980 to 1989, RAI 0%, LAI 0%; 1990 to 1999, RAI 62%, LAI 54%; 2000 to 2009, RAI 59%, LAI 53%; 2010 to 2017, RAI 67%, LAI 75% by era. The rate of intrauterine death remained. Risk factors for death/transplantation for RAI were total anomalous pulmonary venous drainage, left heart obstruction (hazard ratios 2.7, p = 0.048; 5.8, p = 0.03) and for LAI: CHB, anomalous pulmonary venous drainage and right heart obstruction (hazard ratios 11.5, 6.2, 3.8, respectively (p = 0.008, p = 0.003, p <0.001)). In conclusion, laterality disturbances represent a complex form of congenital heart disease and although survival is improved, it remains poor especially in the presence of anomalous pulmonary venous drainage, stenotic and/or atretic valves, and CHB.

Congestive Heart Failure Leads to Prolongation of the PR Interval and Atrioventricular Junction Enlargement and Ion Channel Remodelling in the Rabbit

Heart failure is a major killer worldwide. Atrioventricular conduction block is common in heart failure; it is associated with worse outcomes and can lead to syncope and bradycardic death. We examine the effect of heart failure on anatomical and ion channel remodelling in the rabbit atrioventricular junction (AVJ). Heart failure was induced in New Zealand rabbits by disruption of the aortic valve and banding of the abdominal aorta resulting in volume and pressure overload. Laser micro-dissection and real-time polymerase chain reaction (RT-PCR) were employed to investigate the effects of heart failure on ion channel remodelling in four regions of the rabbit AVJ and in septal tissues. Investigation of the AVJ anatomy was performed using micro-computed tomography (micro-CT). Heart failure animals developed first degree heart block. Heart failure caused ventricular myocardial volume increase with a 35% elongation of the AVJ. There was downregulation of HCN1 and Cx43 mRNA transcripts across all regions and downregulation of Ca_v1.3 in the transitional tissue. Cx40 mRNA was significantly downregulated in the atrial septum and AVJ tissues but not in the ventricular septum. mRNA abundance for ANP, CLCN2 and Na_vβ1 was increased with heart failure; Na_v1.1 was increased in the inferior nodal extension/compact node area. Heart failure in the rabbit leads to prolongation of the PR interval and this is accompanied by downregulation of HCN1, Ca_v1.3, Cx40 and Cx43 mRNAs and anatomical enlargement of the entire heart and AVJ.

Congestive heart failure: experimental model

INTRODUCTION

Surgically induced, combined volume and pressure overload has been used in rabbits to create a simplified and reproducible model of acute left ventricular (LV) failure.

MATERIALS AND METHODS

New Zealand white male rabbits (n = 24, mean weight 3.1 ± 0.2 kg) were randomly assigned to either the Control group (n = 10) or to the Heart Failure group (HF, n = 14). Animals in the Control group underwent "sham" procedures. Animals in the HF group underwent procedures to induce LV volume overload by inducing severe aortic valve regurgitation with aortic cusp disruption and pressure overload using an occlusive silver clip positioned around the pre-renal abdominal aorta.

RESULTS

Following Procedure-1 (volume overload) echocardiography confirmed severe aortic regurgitation in all animals in the HF group, with increased mean pulse pressure difference from 18 ± 3 to 38 ± 3 mmHg (P < 0.0001). After Procedure-2 (pressure overload) all animals in the HF group showed clinical and echocardiographic signs of constriction of the abdominal aorta and echocardiography confirmed progressively declining LV function. At the end of the protocol there was a significant increase of the heart/body weight ratio in the HF group vs. Control group (4.6 ± 0.2 vs. 2.9 ± 0.1 g/kg, P < 0.05), and echocardiography showed in HF group significant increase of the LV end-diastolic diameter (2.15 ± 0.09 vs. 1.49 ± 0.03 cm, P < 0.001) and reduction of the LV shortening fraction (26.3 ± 3.8 vs. 41.3 ± 1.6%, P < 0.001).

CONCLUSION

This experimental model: (a) consistently produces LV hypertrophy/dilatation and subsequent congestive heart failure, (b) provides new data on the time course of LV dilatation, hypertrophy and failure, (c) allows study of the progress and evolution of LV systolic and diastolic dysfunction in the presence of induced LV failure, (d) is suitable to study intervention or pharmacological administration to reduce the negative effects of acute LV failure.

Missed opportunities for identifying primary HIV within genitourinary medical/HIV services

To assess the ability of three genitourinary medical centres to clinically identify primary HIV infection (PHI). Cases of recently acquired HIV infection, identified using the Health Protection Agency (HPA) avidity assay on all HIV diagnoses from January to August 2009, were investigated by case-note review. Sixty-four individuals were identified as PHI using the HPA avidity assay. Of 64 individuals, 31 (48%) were identified clinically. Imperial College identified 8/26 (31%), Guys and St Thomas' 15/27 (56%) and Brighton 8/11 (73%). Clinical suspicion of PHI was associated with reported unprotected anal intercourse (P = 0.017), seroconversion symptoms (P = 0.0004), a negative HIV test within six months (P = 0.024) and avidity assay result availability (P = 0.0169). Seventy percent of PHI cases missed had a documented risk factor. Thirty-five percent of those clinically identified with PHI were documented as informed of the associated enhanced infectivity. Suspicion of PHI was low despite documented risk factors and recent HIV-negative antibody tests. Counselling to prevent onward transmission was suboptimal.

A method to determine when active translocation of nonhuman primates is justified

This article addresses translocation, or artificial dispersal, the movement of one or more organisms from one location to another, and focuses on the decisions to be made before translocation begins. Scientific, economic, or pragmatic reasons such as pest removal or conservation of biodiversity may account for undertaking translocation. When is translocation ethical, and how can that decision be determined? This article provides one quantitative and utilitarian method for evaluating these questions. Although this analysis may apply to any nonhuman species for which costs and benefits can be assessed, the examples in this article derive from the nonhuman primate literature.

Lessons about sleepiness and driving from the Selby rail disaster case: R v Gary Neil Hart

In April 2003, near the town of Selby in North Yorkshire, England, a motor vehicle went off the road to cause a train collision, killing 10 and injuring more than 70 people. The driver of the vehicle, Gary Neil Hart, had allegedly fallen asleep while driving, and was charged and subsequently convicted of causing death by dangerous driving. Evidence from an expert witness was led by the prosecution to establish that Hart had in fact fallen asleep, and that prior to falling asleep, he knew (or ought to have known) that he was at risk of falling asleep but nevertheless continued to drive. The issue of whether and to what extent individuals are aware that they are about to fall asleep has significant implications for criminal prosecutions. Generally, the definition of a criminal offense includes a mental element such as intent or knowledge. Therefore, it is imperative that issues such as whether in every individual there is forewarning of sleep and the degree to which individuals are able to self-assess their ability to continue driving under conditions of extreme sleepiness must be resolved. Sleepiness is now regarded as the largest identifiable and preventable cause of accidents in all modes of transportation. Litigation for such accidents is likely to increase, and therefore it is of great importance that further research be undertaken to examine the process of falling asleep, especially the subjective experiences immediately preceding sleep.

Surgical treatment of olecranon fractures

Fractures of the olecranon are common injuries with no single accepted treatment. Numerous clinical factors and biomechanical studies guide the surgeon in determining a treatment plan. The goals of surgical management include anatomical reduction and stable fixation, which allow early range of motion of the elbow joint. Numerous fixation methods have been described and include screw fixation, cerclage wiring, modified tension-band wiring, and plate fixation. The surgical technique depends on a combination of patient factors, the fracture pattern, and the mechanical stability of the fixation construct. Postoperative rehabilitation includes early active range-of-motion exercises and follows clinical and radiographic healing. Complications are related to the fracture, choice of implant, and surgical technique.

Building health services research capacity in nursing: views from members of nursing's leadership [interview by Candice Cook Bowman and Deborah Gardner]

BACKGROUND

Despite a short history that dates back to the 1960s, health services research (HSR) has become an important force in shaping the delivery system in the current health care environment. Nursing has been noticeably absent from this endeavor, and if it does not increase its presence, it risks missing an important opportunity to influence future directions of health care delivery.

PURPOSE

Our purpose was to evaluate the state of nursing's HSR contributions and to consider ways to increase its capacity in this arena.

METHOD

An interview with four members from nursing's leadership was conducted.

DISCUSSION

Nurses can increase the capacity by becoming better collaborators with those who are currently contributing to HSR, both nurses and members of other healthcare disciplines. Also, by reshaping undergraduate and graduate curricula and creating mentorships, nursing can increase its involvement through an informed workforce.

CONCLUSIONS

Solutions that were offered in this discussion are presented.

Percutaneous stabilization of U-shaped sacral fractures using iliosacral screws: technique and early results

PURPOSE

To present the technique and early results of percutaneous stabilization of U-shaped sacral fractures with attention to neurologic recovery and maintenance of fracture reduction of the sacrum.

DESIGN

Retrospective clinical study.

SETTING

Level I trauma center.

PATIENTS

During a thirty-eight-month period, 442 patients with pelvic ring disruptions were treated at a Level I trauma center. Thirteen (2.9 percent) of these patients had displaced U-shaped sacral fractures treated with percutaneous stabilization.

INTERVENTION

Fracture stabilization was accomplished using fluoroscopically guided iliosacral screws inserted percutaneously with the patient positioned supine. Neurodiagnostic monitoring was not used during screw insertions. This technique was limited to patients with sacral kyphotic deformities, which allowed in situ fixation. Sacral neurologic decompression was not performed.

MAIN OUTCOME MEASUREMENTS

Fracture healing and the stability of fixation were assessed on inlet and outlet radiographs and a lateral sacral view. Detailed neurologic examinations were performed at injury and at follow-up.

RESULTS

The sacral fractures were classified based on plain pelvic radiographs and computed tomography scans and included one Type 1, eight Type 2, and four Type 3 fracture patterns. Twenty-five fully threaded cancellous 7.0-millimeter cannulated screws were used. Eleven patients had bilateral screw fixations; one patient had unilateral double screw fixation; and one patient had unilateral single screw fixation. Operative time for screw insertion averaged forty-eight minutes, with 2.1 minutes of fluoroscopy per screw. Accurate screw insertions without neuroforaminal or sacral spinal canal violations were confirmed in all patients with postoperative pelvic plain radiographs and computed tomography scans. A paradoxical inlet view of the upper sacral segments on the injury anteroposterior pelvis was seen in twelve of thirteen patients (92.3 percent), and the diagnosis was confirmed with the lateral sacral view in all thirteen (100 percent) patients. Preoperatively, sacral kyphosis averaged 29 degrees, whereas postoperative sacral kyphosis averaged 28 degrees. Screw disengagement occurred without a change in position of the sacral fracture in the only patient treated with a single unilateral screw. All fractures healed clinically and radiographically. Of the nine patients with preoperative neurologic abnormalities, two (22 percent) patients had residual neurologic deficits. Both patients had associated multiple level lumbar burst fractures, which required decompression and instrumented stabilization.

CONCLUSIONS

These sacral fractures are rare and occur after significant spinal axial loading. A paradoxic inlet view of the upper sacrum on the anteroposterior plain pelvic radiograph heralds the diagnosis. Delayed diagnosis is avoided by a high clinical suspicion, early lateral sacral radiographs, and pelvic computed tomography scans. Surgical stabilization may assist in early mobilization of the patient from recumbency and prevents progressive deformity with associated nerve root injury. Percutaneous fixation diminishes potential blood loss and operative times, yet still allows subsequent sacral decompression of the local neural elements using open techniques when necessary. Early percutaneous iliosacral screw fixation is effective treatment for these injuries.

Regulation of bleomycin-induced DNA breakage and chromatin structure in lung endothelial cells by integrins and poly(ADP-ribose) polymerase

Activation of endothelial cell integrins inhibits DNA breakage by diverse agents, including the DNA-damaging agent bleomycin. DNA breaks activate nuclear poly(ADP-ribose) polymerase (PARP), which regulates chromatin structure and DNA repair. We determined the role of PARP in suppression of bleomycin genotoxicity by integrins using wild-type and PARP knockout mouse lung endothelial cells (MLEC), and the PARP inhibitor, 3-aminobenzamide (3AB). Activation of beta1 integrins by antibody clustering enhanced the sensitivity of wild-type nuclei to digestion with micrococcal nuclease and deoxyribonuclease I, indicating that chromatin structure was altered. 3AB blocked this effect. Knockout and 3AB-treated wild-type MLEC were hypersensitive to deoxyribonuclease I compared with wild-type cells, demonstrating that PARP regulates chromatin structure. Integrin clustering reduced the hypersensitivity of knockout cells, suggesting additional, PARP-independent mechanisms that inhibit nuclease interaction with chromatin. Bleomycin caused DNA breakage in wild-type and knockout MLEC. Breaks were eliminated after 60 min incubation of wild-type cells in drug-free medium, whereas 3AB or PARP knockout inhibited DNA repair. Integrin clustering protected wild-type cells from DNA breakage, and 3AB and PARP knockout inhibited this protection. Bleomycin caused large increases in PARP activity in wild-type but not knockout MLEC, and integrin clustering inhibited the activation of PARP. The results indicate that the antigenotoxic effects of integrin activation require PARP and that integrins alter chromatin structure by PARP-dependent and -independent mechanisms.

UCN-01 and camptothecin induce DNA double-strand breaks in p53 mutant tumor cells, but not in normal or p53 negative epithelial cells

Previous research has shown synergistic growth inhibition between UCN-01 and camptothecin (CPT) in tumor cells with mutant p53 versus tumor cells with wild-type p53. To determine the possible role of p53 in this drug combination, we tested the hypothesis that the synergistic growth inhibition is due to the absence of p53, and can result from the induction of DNA double-strand breaks (DSBs). Experiments were performed with the use of normal human mammary epithelial cells (HMEC); HMEC transfected with HPV16 E6 protein which inactivates p53 (HE6), or p53-mutant MDA-MB-231 tumor cells. CPT, UCN-01, or a 1:1 combination of both, in either HMEC or HE6 cells did not induce DSBs. In contrast, simultaneous treatment of MDA-MB-231 cells with both UCN-01 and CPT induced significant levels of DSBs while treatment with either drug alone did not. While UCN-01 was surprisingly potent against HMEC, the growth inhibition was only additive between UCN-01 and CPT against these cells. HE6 cells were much less sensitive than HMEC to UCN-01 and slightly less sensitive to the combined treatment with UCN-01 and CPT. The drug combination was synergistic against HE6 cells, due to their lower sensitivity to UCN-01. Unlike what was observed previously in MDA-MB-231 cells, UCN-01 did not abrogate CPT-induced inhibition of DNA synthesis in either HMEC or HE6 cells. These data indicate that synergistic growth inhibition by UCN-01 and CPT against p53 mutant MDA-MB-231 tumor cells may be due to induction of DSBs however the loss of p53 function alone does not sensitize normal cells to the combination of both drugs.

Enhancement of camptothecin-induced cytotoxicity with UCN-01 in breast cancer cells: abrogation of S/G(2) arrest

PURPOSE

To determine the ability of UCN-01 to abrogate the cell cycle arrest induced by camptothecin (CPT) in tumor cells that lack p53 function, and therefore enhance the cytotoxicity of CPT in these cells in relation to normal cells with wild-type p53.

METHODS

The responses of MDA-MB-231 and GI 101A breast cancer cells were compared to those of normal bovine endothelial cells. Cytotoxicity was assessed by the MTT assay, and the resulting data were modeled using median-effect analysis. Inhibition of DNA synthesis was determined by loss of [(3)H]thymidine incorporation, and cell cycle status was determined by flow cytometric analysis of propidium-iodide-stained nuclei.

RESULTS

UCN-01, a specific inhibitor of protein kinase C (PKC) presently in clinical trials, abrogated CPT-induced activation of S and G(2) checkpoints in human MDA-MB-231 and GI 101A breast carcinoma cells, both of which are mutants for the p53 gene. This abrogation occurred with the use of sublethal doses (100 nM) of UCN-01 and correlated with the enhancement of CPT-induced cytotoxicity. Median-effect analysis showed that synergistic cytotoxic interactions existed between CPT and UCN-01 against these tumor cells. In normal cells, however, abrogation of the S phase arrest caused accumulation in G(0)/G(1) phase, perhaps by the presence of wild-type p53 activity, with no change in CPT-induced cytotoxicity.

CONCLUSION

We have shown previously that the cytotoxicity of CPT is correlated with cell cycle response in normal and tumor cells. Low doses of CPT arrest cells in the G(2)/M phase and inhibit DNA synthesis, but higher doses cause arrest of cells in S phase. Thus modulation of events at the S and G(2) checkpoints may provide an opportunity to enhance CPT-induced cytotoxicity in tumor cells. The results of this study indicate that UCN-01 enhances the progression of tumor cells through S phase thus greatly increasing CPT-induced cytotoxicity. Normal cells, however, are able to arrest in G(0)/G(1) and thus avoid the increased toxicity induced by CPT. Our findings suggest potential usefulness of combining UCN-01 in topoisomerase I inhibitor-based drug therapy for the treatment of breast cancer with a dysfunctional p53 gene.

Antiangiogenic potential of camptothecin and topotecan

PURPOSE

To determine the inhibitory nature of sublethal doses of camptothecin (CPT) and topotecan (TPT) treatments on normal human endothelial cells in vitro, as well as the in vivo antiangiogenic activity as compared to another antiangiogenic compound, TNP-470 and to a nonspecific cytotoxic agent, cisplatin.

METHODS

Growth inhibition was determined by the crystal violet assay to measure relative cell numbers. (3)H-thymidine uptake was used to determine the inhibitory effect of CPT and TPT on DNA synthesis in vitro. Cell viability was determined using trypan blue exclusion assays. Cell cycle response to CPT was determined by flow cytometric analysis of propidium iodide-stained nuclei. In vivo inhibition of angiogenesis was determined by the disc angiogenesis system (DAS), where surgical sponge discs were placed subcutaneously in the rat dorsum and the ability of systemic treatment with liposomal CPT (LCPT), TPT, TNP-470 or cisplatin to inhibit vascular growth into the discs was evaluated. Quantitation of vascular growth was determined using toluidine blue staining of sectioned discs followed by digital image analysis.

RESULTS

Treatment with 50 nM CPT or TPT inhibited human umbilical venular endothelial cell (HUVEC) growth as shown by crystal violet staining, but was not cytotoxic to the cells. This was evidenced by the fact that cell numbers did not increase or decrease with treatment, but remained static while cells were viable for over 96 h posttreatment. (3)H-thymidine uptake in HUVEC was inhibited as early as 5 min, reached a maximum inhibition at 24 h and lasted over 96 h posttreatment. Cell cycle analysis of CPT-treated HUVEC showed arrest in S-phase at 12 h with a concurrent decrease in population of cells in G(1). Accumulation of cells at the G(2)/M-phase was discernible at 24 h along with the S-phase inhibition. Treatment of rats with 1 mg/kg LCPT or TPT every other day for 14 days resulted in approximately 30% inhibition of vascular growth into the discs. This inhibition was similar to the inhibition seen with TNP-470, an established and potent angiogenic inhibitor. In contrast, cisplatin was not as effective in inhibiting vascular growth into the discs.

CONCLUSIONS

In this work we showed that CPT and TPT inhibit human endothelial cell growth in vitro in a non-cytotoxic manner and that this inhibition lasts more than 96 h after drug removal. We also showed that LCPT and TPT, unlike a nonspecific cytotoxic agent, cisplatin, are as effective as TNP-470 in inhibiting angiogenic growth in the in vivo disc angiogenesis model. From this observation we propose that in addition to their proven tumoricidal activities, camptothecins may have an indirect in vivo antitumor effect mediated through the inhibition of angiogenesis.

Superior gluteal artery injury during iliosacral screw placement

Percutaneous fixation of an unstable pelvic ring injury is becoming a popular method of pelvic stabilization. As posterior pelvic percutaneous techniques become more common, the possibility of iatrogenic complications increases. This case report describes an injury to the superior gluteal artery during percutaneous iliosacral screw insertion and the treatment of this potentially devastating injury.

Displaced avulsion of the ischial apophysis: a hamstring injury requiring internal fixation

A case is reported of an adolescent sprinter who was chronically disabled by pain after non-operative management for an acute hamstring injury. He had sustained an avulsion fracture of the ischial apophysis with displacement of 2.5 cm. Avulsion fractures of the ischial apophysis with displacement of 2 cm or more are unusual, but they frequently result in a symptomatic non-union, and early diagnosis, open reduction, and internal fixation is to be encouraged.

Sensitivity to camptothecin of human breast carcinoma and normal endothelial cells

PURPOSE

To assess parameters that might determine resistance to the topoisomerase I inhibitor, camptothecin (CPT), the sensitivities of three established human breast cancer cell lines (ER-) and of normal bovine endothelial cells to CPT in the free form and incorporated into liposomes (LCPT), were contrasted with topoisomerase I (topo I) content and activity, and with cell cycle response to CPT treatment.

METHODS

Drug sensitivities were determined using the tetrazolium dye assay and by 3H-thymidine incorporation. Topo I levels were determined by Western blot analysis, and catalytic activity was determined with a plasmid relaxation assay, using nuclear protein from each cell line. CPT stabilization of cleavable complexes in nuclear extracts was determined using a labeled oligonucleotide with a specific topo I cleavage site. Cell cycle response to CPT was determined by flow cytometric analysis of propidium iodide-stained nuclei.

RESULTS

CPT was extremely potent against MDA-MB-157 cells with an IC50 value of 7 nM compared with IC50 values of 150 nM for GI 101A and 250 nM for MDA-MB-231 cells. In contrast, CPT inhibited the incorporation of 3H-thymidine at very low doses in GI 101A and MDA-MB-231 cells with IC50 values of 9 nM and 5 nM, respectively; while MDA-MB-157 cells did not stop incorporating 3H-thymidine until very high doses (500 nM) of CPT were used. When incorporated into multilamellar liposomes (LCPT), CPT retained its potency, with IC50 values similar to that of the free drug. No correlation was found between CPT-induced cytotoxicity and any of the topo I parameters determined. Cell cycle analysis, however, showed an accumulation of cells in G2/M phase after 24 h treatment with low doses (5 nM) of CPT in only GI 101A and MDA-MB-231 cells with no arrest in normal endothelial or MDA-MB-157 cells. At higher doses (50 nM), however, a dramatic accumulation of cells in the S phase was observed in MDA-MB-157, MDA-MB-231 and GI 101A cells. In contrast, a G2/M phase block was seen with the normal bovine endothelial cells using the higher doses of CPT.

CONCLUSIONS

The results suggest that cell cycle regulation plays an important role in determining the effect of CPT on malignant and normal cells. The possible mechanisms explaining the sensitivities of the two cellular compartments to the action of CPT are discussed.

An audit of hospital mortality after urgent and emergency surgery in the elderly

An audit was carried out of 102 patients aged over 75 years undergoing urgent or emergency surgery in a district general hospital. The risk of death in hospital after general surgery (13 deaths in 49 patients) was greater than after orthopaedic surgery (two deaths in 53 patients) (P < 0.05). In particular, laparotomy carried a high in-hospital mortality: 12 of 25 patients undergoing laparotomy died. Risk of death after general surgery increased with increasing preoperative ASA class, increasing medical risk factors and duration of operation. Orthopaedic cases were fitter than the general surgical cases as determined by ASA class and the number of medical risk factors. NCEPOD has recommended increased involvement of senior medical staff in operations, reduced night-time operating and avoidance of futile surgery. A high proportion of cases were operated on and anaesthetised by higher specialist trainees and consultants. Death rate was not affected by the seniority of doctors involved, nor by the time of day the operation took place. General surgical deaths were predictable postoperatively in most cases, but preoperative prediction of outcome was not specific enough to alter management.

Synthesis, structure-activity relationships, and pharmacokinetic properties of dihydroorotate dehydrogenase inhibitors: 2-cyano-3-cyclopropyl-3-hydroxy-N-[3'-methyl-4'-(trifluoromethyl)phenyl ] propenamide and related compounds

The active metabolite (2) of the novel immunosuppressive agent leflunomide (1) has been shown to inhibit the enzyme dihydroorotate dehydrogenase (DHODH). This enzyme catalyzes the fourth step in de novo pyrimidine biosynthesis. A series of analogues of the active metabolite 2 have been synthesized. Their in vivo biological activity determined in rat and mouse delayed type hypersensitivity has been found to correlate well with their in vitro DHODH potency. The most promising compound (3) has shown activity in rat and mouse collagen (II)-induced arthritis models (ED50 = 2 and 31 mg/kg, respectively) and has shown a shorter half-life in man when compared with leflunomide. Clinical studies in rheumatoid arthritis are in progress.

The nursing practice environment, staff retention, and quality of care

The effects of key factors in the nursing practice environment--management style, group cohesion, job stress, organizational job satisfaction, and professional job satisfaction--on staff nurse retention and process aspects of quality of care were examined. Hinshaw and Atwood's (1985) anticipated turnover model was modified and expanded to include relevant antecedent and outcome variables. The four-stage theoretical model was tested using data from 50 nursing units at four acute care hospitals in the southeast. The model explained 49% of the variance in staff nurse retention and 39% of the variance in process aspects of quality of nursing care. Study findings warrant careful consideration in light of recent practice environment changes: experience on the unit and professional job satisfaction were predictors of staff nurse retention; job stress and clinical service were predictors of quality of care. The variable contributing the most to indirect, and in turn, total model effects, was that of management style. These results substantiate the belief that aspects of the practice environment affect staff nurse retention, and most importantly, the quality of care delivered on hospital nursing units.

Ventilator-associated pneumonia due to Pseudomonas aeruginosa

OBJECTIVE

Ventilator-associated pneumonia (VAP) caused by Pseudomonas aeruginosa has been associated with higher case fatality rates than VAP caused by other bacterial etiologies. The causes of this excess mortality are unclear.

DESIGN

Retrospective review of 38 consecutive ventilated patients with Pseudomonas pneumonia, documented by highly reliable methods. Charts of five additional patients were unavailable for review.

SETTING

Medical ICUs of a university-affiliated Veterans Affairs Medical Center and a university-affiliated municipal hospital.

MEASUREMENTS

Prospectively collected hospital admission acute physiologic and chronic health examination (APACHE) II scores and cause of ICU admission. Retrospectively calculated organ failure and APACHE scores, VAP score. Clinical and microbiologic variables. Antibiotic treatment and outcome. Direct cause of death by standard definitions.

RESULTS

Overall mortality was 69% (26/38), significantly higher than the APACHE II predicted mortality of 42.6% (p=0.037). At least 38% (10/26) of deaths were directly attributable to Pseudomonas VAP. Multivariate analysis of factors associated with death found infectious cause for ICU admission (odds ratio [OR]=8.67; 95% confidence interval [CI], 0.86 to 85.94) and number of organ dysfunctions on the day of diagnosis (OR=1.73, 95% CI, 1.02 to 2.92) were significant. Septic shock from Pseudomonas VAP, septic shock from subsequent infection, and multiple organ dysfunction syndrome were the most common immediate causes of death. Mortality increased linearly with increasing APACHE III score on the day of diagnosis. Of initial antibiotic regimens, 67% (26/36) were considered failures. Persistent pneumonia occurred in 35% of patients while recurrent pneumonia was unusual (1/38).

CONCLUSIONS

Development of Pseudomonas pneumonia results in a mortality rate in excess of that due to the presenting illness. The attributable mortality determined by several means appears to approach 40%. The excess mortality appears to be related to the host defense response to the pneumonia rather than any characteristic of the pneumonia. Even standard antibiotic regimens fail frequently and do not prevent the excess mortality. Since at least 38% of deaths can be directly attributable to the Pseudomonas pneumonia, improvement in therapy is needed.

Hydroxylation of lauramide diethanolamine by liver microsomes

Lauramide diethanolamine (LDEA)--a compound used in cosmetics and soap products as an emollient, thickener, and foam stabilizer--was observed to be metabolized by rat liver microsomes to two major products that were identified by GC/MS to be the 11-hydroxy and 12-hydroxy derivatives of LDEA. The specific activities for LDEA 11- and 12-hydroxylation in microsomes prepared from control rats were 2.23 +/- 0.40 and 0.71 +/- 0.17 nmol/min/mg protein, respectively. Treatment of rats with the cytochrome P4504A inducer and peroxisome proliferator, diethylhexyl phthalate, increased the LDEA 12-hydroxylation rate to 3.50 +/- 0.48 nmol/min/mg protein, a 5-fold increase in specific activity, whereas the LDEA 11-hydroxylase activity remained unchanged. Because LDEA contains a 12-carbon side chain, LDEA hydroxylation rates were compared with the hydroxylation rates for lauric acid. The specific activities of lauric acid 11- and 12-hydroxylation reactions in diethylhexyl phthalate-treated rats were 1.7-fold and 3.2-fold greater than the LDEA 11- and 12-hydroxylation rates, respectively. When LDEA hydroxylation reactions were performed in the presence of a polyclonal antibody to the rat P4504A forms, formation of 12-hydroxy-LDEA was inhibited by 80%. Rat kidney microsomes also supported the hydroxylation of LDEA at its 11- and 12-carbon atoms, with specific activities of 0.05 +/- 0.01 and 0.28 +/- 0.02 nmol/min/mg protein, respectively. LDEA was also metabolized to 11- and 12-hydroxy derivatives by human liver microsomes at specific activities of 0.22 +/- 0.06 and 0.84 +/- 0.26 nmol/min/mg protein, respectively.

Ventilator-associated Pseudomonas aeruginosa pneumonia: radiographic findings

PURPOSE

To characterize the radiographic features of ventilator-associated Pseudomonas aeruginosa pneumonia (PAP).

MATERIALS AND METHODS

In 56 patients (40 men and 16 women), PAP was documented with fiberoptic bronchoscopy. All patients underwent mechanical ventilation for at least 48 hours before diagnosis. The findings on chest radiographs were recorded. In eight patients in whom computed tomography (CT) was performed, results were compared with radiographic findings.

RESULTS

Twenty-six patients with adult respiratory distress syndrome (ARDS) had diffuse bilateral confluent opacities; 30 patients without ARDS had multifocal opacities. In 13 patients, cavities were detected at chest radiography, CT, or both. Seven of 29 patients with pleural abnormalities had empyema. CT provided important additional information (presence of cavities or effusions) in four cases.

CONCLUSION

Findings on chest radiographs are nonspecific for PAP. The frequencies of cavities and empyema are surprisingly low, perhaps owing to prompt diagnosis and therapy.

Causes of fever and pulmonary densities in patients with clinical manifestations of ventilator-associated pneumonia

BACKGROUND

Ventilator-associated pneumonia, a leading cause of sepsis in patients with acute respiratory failure, is difficult to distinguish clinically from other processes affecting patients receiving mechanical ventilation. We conducted a prospective study of patients with suspected ventilator-associated pneumonia to identify the causes of fever and densities on chest radiographs and to evaluate the diagnostic yield and efficiency of tests used alone and in combination.

METHODS

The 50 patients entered into the study underwent a systematic diagnostic protocol designed to identify all potential causes of fever and pulmonary densities. Diagnoses responsible for fever were established by strict diagnostic criteria for 45 of the 50 patients. The prevalence of specific conditions and diagnostic yield of individual tests were used to formulate a simplified diagnostic protocol.

RESULTS

The diagnostic protocol identified 78 causes of fever (median 2 per patient). Infections were the leading causes of fever and pulmonary densities. Of the 45 patients with fever, 37 had one or more infections identified (67 sources). Most infections (84 percent) were one of four types:pneumonia, sinusitis, catheter-related infection, or urinary tract infection. Ventilator-associated pneumonia occurred in only 42 percent. All but nine infections (87 percent) were directly or indirectly related to insertion of a catheter or a tube. Concomitant infections were frequent (62 percent), particularly in patients with sinusitis (100 percent), catheter-related infections (93 percent), and pneumonia (74 percent). Of concomitant infections, 60 percent were caused by a different pathogen. Noninfectious causes of fever were more common in the 22 patients with adult respiratory distress syndrome. Histologically proved pulmonary fibroproliferation was the only cause of fever in 25 percent of patients with adult respiratory distress syndrome. Radiographic densities were caused by an infection in only 20 patients (19 pneumonia, 1 empyema). In more than 50 percent of the 25 patients without adult respiratory distress syndrome, congestive heart failure, and atelectasis were the sole causes of pulmonary densities, and fever always originated from an extrapulmonary site of infection. Used in combination, bronchoscopy with protected sampling, computed tomographic scan of the sinuses, and cultures of maxillary sinus aspirate, central intravenous or arterial lines, urine, and blood identified 58 of the 78 sources of fever (74 percent).

CONCLUSIONS

The observations in this study document the complex nature of acute respiratory failure and fever and underscore the need for accuracy in diagnosis. The frequent occurrence of multiple infectious and noninfectious processes justifies a systematic search for source of fever, using a comprehensive diagnostic protocol. A simplified diagnostic protocol was devised based on the diagnostic value of individual tests.

What is a reasonable orthopaedic surgical workload? An analysis of elective and trauma workloads using two different complexity scoring systems

A 1-year prospective study of all surgical activity was undertaken by the Orthopaedic Unit using two weighting systems for operative complexity: the Intermediate Equivalent (IE) and the Operative Complexity Score (OCS). The objectives were to define the difference between caseload and workload, and to formulate a reasonable workload for an operating session and a reasonable annual workload for a consultant team. In both elective and trauma surgery the BUPA complex, major+ and major operations represented 50 per cent of the caseload but accounted for approximately 68 per cent of the workload. The BUPA minor and intermediate procedures representing the remaining 50 per cent of the caseload accounted for only 32 per cent of the workload. The number of hours required to undertake all the complex, major+ and major operations was approximately twice that required for the number of minor and intermediate procedures. Despite the marked variation in case mix, the workload achieved by the six teams in the same number of sessions was remarkably similar. On the basis of two consultant and one registrar elective lists per week, a total of 705 IEs (1795 OCS units) could be undertaken by each team in 1 year. An average of 458 IEs (1086 OCS units) of trauma surgery were undertaken by each team. Caseload is a poor performance indicator of surgical activity. This study supports the concept of 3.5-4.0 IEs as reasonable workload for an orthopaedic elective operating session, and 900 IEs (2200 OCS units) as a reasonable annual workload for an orthopaedic team.

Shared governance and the nursing practice environment

An evaluation of the impact of shared governance on staff nurse perceptions of management style, group cohesion, job stress, job satisfaction, and anticipated turnover provides support for claims that shared governance improves the nursing practice environment.