Resting lung function in children after repair of tetralogy of Fallot

Evaluation of Pulmonary Hypoplasia in Various Congenital Anomalies with a Comparison of Two Conventional Methods of Assessment: Radial Alveolar Count (RAC) and Lung Weight: Body Weight Ratio (LBW)

OBJECTIVE

Pulmonary hypoplasia is common in the perinatal period and causes death in newborn infants. It is commonly associated with a number of malformation syndromes. Various parameters are used to estimate pulmonary hypoplasia at fetal autopsy including Lung Weight Body Weight ratio (LW:BW), Radial Alveolar Count (RAC) and DNA estimation.

MATERIAL AND METHOD

This study was carried out as a retrospective analysis of 108 lung specimens of fetuses with congenital anomalies for a period of five years. All terminated fetuses with anomalies were received with 10% formalin. An inverted Y-shaped incision was made on the fetus to remove the lungs. Lung weight and body weight were measured and the ratio was calculated. Morphometric estimation of RAC was done microscopically by counting the number of alveoli using the Q capture software. RAC was calculated based on gestational age.

RESULTS

Among the restrictive lung diseases, pulmonary hypoplasia by the LW:BW ratio was prevalent in 43% while the same by RAC was 19%. Similarly, pulmonary hypoplasia by the LW:BW ratio was prevalent in 35% while the same by RAC was 26% among cases with non restrictive lung diseases. Oligohydramnios showed the highest prevalence of pulmonary hypoplasia (23.7%), followed by renal anomalies (16.9%) and CNS anomalies (15.2%).

CONCLUSION

Pulmonary hypoplasia is a common occurrence in many congenital anomalies, premature rupture of membranes, and hydrops fetalis. Identifying the anomaly during the intrauterine period will help to anticipate and accordingly manage the baby in the postpartum period. Early diagnosis of correctable condition like oligohydramnios will also help in the early intervention and prevention of pulmonary hypoplasia.

Resting respiratory lung volumes are "healthier" than exercise respiratory volumes in different types of palliated or corrected congenital heart disease

AIMS

Cardiac surgery has improved life expectancy of patients with congenital heart diseases (CHDs). Exercise capacity is an important determinant of survival in patients with CHDs. There is a lack of studies focusing on the role of resting respiratory performance in reducing exercise tolerance in these patients.

OBJECTIVES

To determine the prevalence and severity of respiratory functional impairment in different types of corrected/palliated CHDs, and its impact on an exercise test.

MATERIALS AND METHODS

Retrospective single-center study involving 168 corrected/palliated patients with CHD and 52 controls. Patients CHD were divided into subgroups according to the presence of native pulmonary blood flow or total cavopulmonary connection (TCPC). All subjects performed complete pulmonary function tests and gas diffusion; patients with CHD also performed cardiopulmonary exercise test (CPX).

RESULTS

Mean values of lung volumes were within the normal range in all CHD groups. Comparing to controls, patients with the reduced pulmonary flow and with TCPC had the highest reduction in lung volumes. CPX was reduced in all groups, most severely in TCPC, and it was correlated to decreased dynamic volumes in all CHD groups except in TCPC. Younger age at intervention and number of surgical operations negatively affected lung volumes.

CONCLUSIONS

Respiratory function is within the normal range in our patients with different CHDs at rest but altered in all CHDs during exercise when cardiorespiratory balance is likely to be inadequate. Comparing the different groups, patients with reduced pulmonary flow and TCPC are the most impaired.

Pulmonary effects on exercise testing in tetralogy of Fallot patients repaired with a transannular patch

BACKGROUND

A transannular patch is often used in the contemporary surgical repair of tetralogy of Fallot. This can lead to significant pulmonary insufficiency and increased right ventricular volumes and ultimately pulmonary valve replacement. Cardiopulmonary exercise testing is used to assess exercise capacity in tetralogy of Fallot patients before pulmonary valve replacement. There is only few published literatures on how lung function affects functional capacity in tetralogy of Fallot patients repaired with a transannular patch.

METHODS

A retrospective chart review was done from 2015 to 2017 on patients with tetralogy of Fallot who underwent maximal effort cardiopulmonary exercise testing with cycle ergometry and with concurrent pulmonary function testing. Tetralogy of Fallot patients repaired with a transannular patch without pulmonary valve replacement were compared with age, gender, and size-matched normal controls.

RESULTS

In the tetralogy of Fallot group, 24 out of 57 patients underwent primary repair with a transannular patch. When compared to the normal controls, they demonstrated abnormal predicted forced expiratory volume in one second (79 ± 23.1% versus 90.7 ± 14.1%, p<0.05), predicted maximal voluntary ventilation (74 ± 18% versus 90.5 ± 16.2%, p<0.05) while having low-normal predicted forced vital capacity (80.5 ± 17.2% versus 90.2 ± 12.4%, p<0.05) and normal breathing reserve percentage (50.3 ± 11.3% versus 47.5 ± 17.3%, p = 0.52). Cardiopulmonary exercise testing abnormalities included significantly lower percent predicted oxygen consumption (63.2 ± 12.2% versus 87 ± 12.1%, p<0.05), maximal heart rate (171.8 ± 18.9 versus 184.6 ± 13.6, p<0.05), and percent predicted maximum workload (61.7 ± 15.9% versus 88.3 ± 21.5%, p<0.05).

CONCLUSIONS

Tetralogy of Fallot patients repaired with a transannular patch can have abnormal pulmonary function testing with poor exercise capacity in addition to chronotropic incompetence and impaired muscular power.

Impact of Non-cardiac Comorbidities in Adults with Congenital Heart Disease: Management of Multisystem Complications

The prevalence and impact of non-cardiac comorbidities in adult patients with congenital heart disease increase over time, and these complications are often specifically a consequence of the long-term altered cardiovascular physiology or sequelae of previous therapies. For the ACHD patient admitted to the intensive care unit (ICU) for either surgical or medical treatment, an assessment of the burden of multisystem disease, as well as an understanding of the underlying cardiovascular pathophysiology, is essential for optimal management of these complex patients. This chapter takes an organ-system-based approach to reviewing common comorbidities in the ACHD patient, focusing on conditions that are directly related to ACHD status and may significantly impact ICU care.

When the Heart Is Not to Blame: Managing Lung Disease in Adult Congenital Heart Disease

It is well-recognized now that adult survivors with congenital heart disease (CHD) are at risk for non-cardiac co-morbidities and complications that can impact symptoms and clinical outcomes. Lung disease, in particular, is common in this population, but likely an under-recognized and undertreated cause for long-term morbidity. Abnormal lung function contributes to exercise intolerance and is associated with a higher risk for mortality in this population. The exact mechanisms that contribute to abnormal measurements of lung function are not entirely known, and are likely multifactorial and variable depending on the underlying CHD. Nevertheless, lung disease is a potentially modifiable risk factor in this patient population, the management of which may result in improved clinical outcomes. This review summarizes our current understanding of the prevalence, impact and management of lung disease in adults with CHD.

The respiratory system in pediatric chronic heart disease

Cardiovascular disease in the pediatric population closely affects the respiratory system inducing water retention in the lungs and pulmonary edema, airway compression by cardiovascular structures, restrictive pulmonary physiology as a result of hemodynamic changes and surgical repair, susceptibility to respiratory infections, development of pulmonary hypertension, thrombosis, or hemorrhage. Chronic heart failure and congenital heart disease are characterized by various respiratory manifestations and symptoms mimicking lung disease, which are frequently difficult to diagnose and treat. Pulmonary function is multiply affected in pediatric heart disease with mostly restrictive but also obstructive and diffusion abnormalities. Patients with Fontan circulation represent a separate group with slow, passive pulmonary blood flow and distinct pathophysiology with low cardiac output heart failure, restrictive lung pattern, increased thromboembolic complications and rare conditions such as protein losing enteropathy and plastic bronchitis. Distinguishing between cardiovascular and pulmonary symptoms may be challenging in the growing population of pediatric and adult survivors of congenital heart disease and understanding of the relationship of the two systems in heart disease is crucial for the optimal management of these patients.

Prognostic Implication of the QRS Axis and its Association with Myocardial Scarring in Patients with Left Bundle Branch Block

Background and Objectives

Left bundle branch block (LBBB) with left axis deviation (LAD) has a worse prognosis than LBBB with a normal axis, and myocardial dysfunction has been suggested as a cause of left axis deviation. This study investigated the prognostic significance of the QRS axis in patients with LBBB and analyzed its relationship with the amount of myocardial scarring.

Subjects and Methods

A total of 829 patients were diagnosed with LBBB at Seoul National University Hospital from October 2004 to June 2014. Of these, 314 who were asymptomatic and had no previous history of cardiac disease were included in the present study. Myocardial scarring was calculated using the Selvester QRS scoring system, and LAD was defined as a QRS axis between -180° and -30°.

Results

Of the total patients, 91 (29%) had LAD, and patients were followed for a median of 30 months. During follow-up, two patients were hospitalized for de novo heart failure, four had pacemaker implants, and 10 died. There was a significant inverse correlation between myocardial scar score and the QRS axis (r=-0.356, p<0.001). Patients with concomitant LAD had a higher rate of major cardiac adverse events compared with patients with a normal axis (5.5% vs. 1.3%, log-rank p=0.010); the prognostic value was attenuated in multivariable analysis (hazard ratio 4.117; 95% confidence interval 0.955-17.743; p=0.058).

Conclusion

Concomitant LAD is an indicator of poor prognosis for patients with LBBB and may be associated with greater myocardial scarring.

Short-Term Change of Exercise Capacity in Patients with Pulmonary Valve Replacement after Tetralogy of Fallot Repair

BACKGROUND AND OBJECTIVES

The aim of this study was to investigate the effect of pulmonary valve replacement (PVR) on exercise capacity and determine cardiopulmonary exercise (CPEX) parameters associated with improvement in right ventricle (RV) function.

SUBJECTS AND METHODS

We retrospectively analyzed CPEX and magnetic resonance imaging parameters in a total of 245 patients who underwent PVR from January 1998 to October 2015. In addition, we analyzed the characteristics of the patients who showed improved exercise capacity after PVR.

RESULTS

Twenty-eight patients met the inclusion criteria for the study. CPEX parameters after PVR showed no significant changes in all patients. However, baseline predicted peak oxygen uptake (VO2_peak) (%) value was significantly lower in patients with significant improvement in exercise capacity after PVR, as compared to patients who showed decreased exercise capacity after PVR (60.83±10.28 vs. 75.81±13.83) (p=0.003). In addition, patients with improved exercise capacity showed a positive correlation between the change of right ventricular ejection fraction (RVEF) (%) and the change of anaerobic threshold (r=0.733, p=0.007); whereas, patients with decreased exercise capacity showed a negative correlation between the change of RVEF (%) and the change of predicted VO2_peak (%) (r=-0.575, p=0.020).

CONCLUSION

The importance of predicted VO2_peak (%) in evaluating exercise capacity differentiated from other CPEX variables. The change of anaerobic threshold and predicted VO2_peak (%) might be a useful predictor of the change in RV function after PVR.

Why exercise capacity does not improve after pulmonary valve replacement

Optimal timing of pulmonary valve replacement (PVR) for pulmonary regurgitation is a debated topic. It is logical that maximal aerobic capacity (VO2peak) would decline when a PVR is needed, but a diminished VO2peak is not always present before PVR, and previous studies show no improvement in VO2peak after PVR. This study aimed to evaluate changes in resting spirometry from pre- to post-PVR sternotomy, to determine the limiting factors of VO2peak before and after PVR, and to determine whether changes in resting lung function after PVR may explain the lack of improvement in VO2peak after surgery. For 26 patients (age, 19.7 ± 7.8 years) with a history of right ventricular outflow tract revision, the study prospectively evaluated echocardiograms, resting spirometry, and maximal exercise tests before PVR and then an average of 15 months after PVR. Flow volume loops were reviewed by a pulmonologist and categorized as obstructive, restrictive, both obstructive and restrictive, or normal. Exercise tests were interpreted using Eschenbacher's algorithm to determine the primary factors limiting exercise. No change in VO2peak or spirometry after PVR was observed. Before PVR, many patients had abnormal resting lung functions (85 % abnormal), which was unchanged after PVR (86 5 % abnormal). The majority of the patients had a ventilatory limitation to VO2peak before PVR (66.7 %), whereas 28.5 % had a cardiovascular limitation, and 4.8 % had no clear limitation. After PVR, 65.2 % of the patients had a ventilatory limitation, whereas 30.4 % had a cardiovascular limitation, and 4.4 % had no clear limitation to VO2peak. Pulmonary function did not change up to 15 months after surgical PVR. The frequency of pulmonary limitation to VO2peak after PVR did not increase. The effect of pulmonary function on exercise-related symptoms must be considered in this patient population. Improved cardiac hemodynamics are unlikely to improve VO2peak in a primarily pulmonary-limited patient.

Pulmonary hypoplasia associated with congenital heart diseases: a fetal study

Background

Abnormalities of the fetal pulmonary vasculature may affect lung morphogenesis. Postnatal studies have suggested that pulmonary hypoplasia (PH) may be associated with congenital heart diseases (CHDs).

Objective

To determine the prevalence of PH associated with CHDs, and to evaluate whether CHDs with right outflow obstruction were associated with the highest risk of lung growth impairment.

Methods

Between January 2006 and December 2010, fetuses with CHD obtained following the termination of pregnancies due to fetal abnormalities were examined in a prospective manner for the detection of heart and lung defects. CHDs were classified into five pathophysiological groups. Lung weight (LW), body weight (BW), and LW/BW ratio were analyzed for each case. The expression of CD31 and VEGF in the lung was evaluated by immunohistochemistry.

Results

Fetuses with CHDs and right outflow obstruction had significantly lower LW for a given BW, and significantly lower LW/BW ratios for a given gestational age. When defining PH as a fetal LW/BW ratio <0.015 before 28 weeks, and <0.012 after 28 weeks, PH was detected in 15 of the 119 fetuses analyzed (13%). It was significantly associated with CHD with right outflow obstruction, independently of chromosomal abnormalities and associated extracardiac abnormalities (p<0.03). Right outflow obstruction was detected in 60% of the fetuses with CHD and PH, but in only 32% of those with CHD but no PH. In fetuses with right outflow obstruction, no difference was observed between those with PH and those without PH, in terms of the ratio of pulmonary artery diameter to aortic diameter, lung CD31 expression, or lung VEGF expression.

Conclusion

CHDs with right outflow obstruction are a significant risk factor for prenatally acquired PH. The occurrence of fetal PH is not correlated with abnormalities of the pulmonary vasculature, suggesting the involvement of perfusion-independent mechanisms.

Exercise in children with common congenital heart lesions: balancing benefits with risks

Children with corrected common congenital heart lesions are often withheld from regular exercise by their parents. While there are some modest risks with exercise, they should be seen in perspective, and the life-long benefits of regular exercise on general health, mood and well-being should be emphasised.

Restrictive lung function in pediatric patients with structural congenital heart disease

OBJECTIVES

We sought to describe the prevalence of restrictive lung function in structural congenital heart disease and to determine the effect of cardiothoracic surgical intervention.

METHODS

The data from a retrospective review of the spirometry findings from pediatric patients with structural congenital heart disease were compared with the data from 220 matched controls. Restrictive lung function was defined as a forced vital capacity of <80%, with a preserved ratio of the forced expiratory volume in the first second to forced vital capacity of >80%.

RESULTS

Of the children with congenital heart disease, 20% met the criteria for restrictive lung function compared with 13.2% of the controls (P = .03). The prevalence in those with congenital heart disease without a surgical history was similar to that of the controls (odds ratio, 0.62; 95% confidence interval, 0.34-1.13). Restrictive lung function was more likely if surgical intervention had occurred within the first year of life (odds ratio, 1.96; 95% confidence interval, 1.08-3.55; P < .0001). Those who had undergone both sternotomy and thoracotomy had a greater prevalence of restrictive lung function than those who had undergone sternotomy or thoracotomy alone (54.2% vs 25.6% and 23.5%, respectively; P < .0001). The prevalence of restrictive lung function increased significantly with each additional surgical intervention (odds ratio, 1.61; 95% confidence interval, 1.29-2.01; P < .0001).

CONCLUSIONS

Restrictive lung function was more prevalent in those with congenital heart disease after cardiothoracic surgical intervention than in the controls or patients without surgical intervention. The prevalence was also greater with surgical intervention at an earlier age. The risk was equivalent when sternotomy alone was compared with thoracotomy alone but was significantly greater when both sternotomy and thoracotomy were performed. The risk increased with each additional surgery performed.

Pulmonary complications of congenital heart disease

Cardiac and pulmonary pathophysiologies are closely interdependent, which makes the management of patients with congenital heart disease (CHD) all the more complex. Pulmonary complications of CHD can be structural due to compression causing airway malacia or atelectasis of the lung. Surgical repair of CHD can also result in structural trauma to the respiratory system, e.g., chylothorax, subglottic stenosis, or diaphragmatic paralysis. Disruption of the Starling forces in the pulmonary vascular system in certain types of CHD lead to alveolar-capillary membrane damage and pulmonary oedema. This in turn results in poorly compliant lungs with a restrictive lung function pattern that can deteriorate to cause hypoxemia. The circulation post single ventricle palliative surgery (the so called "Fontan circulation") poses a unique spectrum of pulmonary pathophysiology with restrictive lung function and a low pulmonary blood flow state that predisposes to thromboembolic complications and plastic bronchitis. As the population of patients surviving post CHD repair increases, the incidence of pulmonary complications has also increased and presents a unique cohort in both the paediatric and adult clinics.

Pulmonary function in children after surgical and percutaneous closure of atrial septal defect

This study aimed to study differences in lung function after surgical and percutaneous atrial septal defect (ASD) closure. Several studies have demonstrated abnormalities of pulmonary function in adults and children with ASD. These abnormalities persist even a few years after correction. This study compared pulmonary function between patients who underwent ASD closure by surgery and those who had closure by device. This is the ideal pediatric population for studying changes in lung function caused by cardiopulmonary bypass or sternotomy. The 46 patients in this study were treated by percutaneous closure (group 1) or surgical closure (group 2) of ASD and then scheduled for pulmonary function testing an average of 5.8 years after ASD closure. The mean values of functional residual capacity, total lung capacity, and residual volume did not differ between the two groups. The surgical group showed a significant decrease in expiratory reserve volume (p < 0.04) and forced vital capacity (p < 0.03). Expiratory flow at 25, 50, and 75% of forced vital capacity did not differ between the two groups but was on the lower limit of normal in both groups. Percutaneous closure of ASD can minimize the side effects of surgical closure on lung function. Longitudinal lung function follow-up assessment after cardiac surgery is warranted to detect and measure restrictive abnormalities in this type of congenital heart disease and others.

Pulmonary function and ventilatory limitation to exercise in congenital heart disease

Pulmonary function in older children and adolescents following surgical repair of congenital heart disease is often abnormal for various reasons. Many of these patients report symptoms of exercise intolerance although the reason(s) for this symptom can be complicated and sometimes interrelated. Is it simply deconditioning due to inactive lifestyle, chronotropic or inotropic insufficiency? or could there indeed be ventilatory limitation to exercise? These are the questions facing the clinician with the increasing frequency of patients undergoing repair early in life and growing into adulthood. Understanding pulmonary functional outcomes and means of determining ventilatory limitation to exercise is essential to thoroughly address the problem. This article reviews pulmonary function in patients with congenital heart disease and then describes a newer technique that should be applied to determine ventilatory limitation to exercise.

Infant lung function testing in the intensive care unit

As a result of the previous shortage of tools to assess objectively the overall physiological status of the respiratory system in infants and young children, it has been difficult to measure the degree of physiological disorder or the response to therapy in respiratory diseases such as BPD, the pediatric version of ARDS, bronchiolitis, pneumonia, asthma and croup in this patient population. The newborn- four-year old child is particularly difficult to study because of their lack of cooperation and size. The recent progress in computer technology made pulmonary function testing available for this age range and opened up new possibilities for monitoring changes in disease processes affecting the respiratory system. This may improve medical management of infants and children with lung and heart diseases in particular. In 1989, Shannon [49] proposed in this Journal that the minimum physiological information needed for the intelligent use of mechanical ventilation (particularly if lower airway and/or pulmonary parenchymal disease was apparent) required the measurement of at least 4 variables: i) arterial partial pressure of carbon dioxide; ii) arterial oxygen saturation; iii) the mechanical time constant of the lung and iv) FRC. In many circumstances, arterial CO2 is approximated by alveolar (end-tidal) CO2 and the arterial oxygen saturation is obtained from pulse oximetry accurately if perfusion is adequate. The mechanical time constant and FRC are easily measured by the techniques described above and together provide important information concerning appropriate ventilator settings for a given disease. The described techniques bring new insights and awareness, but also new responsibilities in the management of infants and children with respiratory compromise. Not all of these techniques need to be applied to all infants in the ICU. Not all the assumptions upon which some of the techniques we have described are based will prove true. Any such methods which do not withstand solid scientific testing must be quickly discarded and replaced with better and (hopefully) easier methods.

Lung function in children and adolescents with tetralogy of Fallot after intracardiac repair

We studied lung function in 41 patients, aged 6-27 years, 1-5 years after intracardiac surgical repair (ICR) of tetralogy of Fallot (TOF) and about 5 years after the establishment of the Pediatric Cardiac Center in Prague. The measurements included vital capacity (VC), total lung capacity (TLC), functional residual capacity (FRC), residual volume (RV), forced expiratory flows (FEF), specific airway conductance (SGaw), lung recoil pressure (Pst), and specific static lung compliance (SC1st). Single or multiple abnormal lung function parameters were found in 83% of patients. Lung function was not related to shunting operations prior to ICR, hemoglobin concentration, and hematocrit, and had no specific pattern. Pst at 100% TLC and 90% TLC declined with increasing age at ICR and at lung function testing, while SC1st rose, as did the ratio FRC/TLC. Fifteen patients were studied before and after surgery. Single or multiple lung function tests were abnormal in 93% before and in 84% after ICR. After ICR the ratios FRC/TLC and also RV/TLC, FEF at 25% VC, and FEF at 60% TLC were less frequently abnormal, while Pst at 100% TLC and at 90% TLC, as well as SGaw and TLC, were more frequently abnormal after ICR. The results indicated a regression of smaller airway obstruction and lung hyperinflation after ICR. The evolution of abnormally compliant (emphysematous) lungs with growth of the patients might be a sign of permanent sequelae of early lung damage from abnormal pulmonary hemodynamics.