Heterotaxy in southern Nevada: prenatal detection and epidemiology

The relationship between brain and visceral asymmetry: Evidence from situs inversus in humans

This review examines the relationship between visceral and brain asymmetry and explores whether their alignment observed in some vertebrate species also exists in humans. While the development of visceral and brain asymmetry may have occurred for different reasons, it is possible that the basic mechanisms for left-right differentiation of the visceral system were duplicated in the brain. We describe the main phenotypical anomalies and the general mechanism of left-right differentiation in vertebrates, followed by a systematic review of available human studies on behavioral and brain asymmetry in individuals with reversed visceral organization. The available evidence shows no direct link between human visceral and brain laterality. Most individuals with situs inversus totalis (SIT) show typical population biases for handedness and brain functional asymmetry, although an increased prevalence of atypical hemispheric segregation may be present. Perisylvian brain structural asymmetries also reveal the expected population bias in participants with SIT. However, several independent studies indicate that SIT is associated with a general reversal of the gross morphologic asymmetry of brain torque. Potential differences in brain structural and functional asymmetries between subtypes of situs inversus with ciliary and nonciliary causes remain to be determined.

Infantile hypertrophic pyloric stenosis, the cause of non-bilious vomiting of a 3-day-old male infant with situs inversus totalis: A case report

The synchronicity of situs inversus totalis (SIT) and infantile hypertrophic pyloric stenosis (IHPS) is rare. We have reported a case of this concurrency in a 3-day-old newborn with classic symptoms.

Pulmonary Versus Systemic Outflow Obstruction in Functionally Univentricular Hearts with Isomerism: An Observation

Our objective was to review our experience with isomerism associated with univentricular hearts and evaluate the prevalence of pulmonary versus systemic outflow obstruction. We identified those prenatally or postnatally diagnosed, between September 2004 and October 2021, with right and left isomerism and a functionally univentricular heart. We identified 62, 51 prenatally and 11 postnatally. Of the 62, 61 had prenatal care for an 84% (51/61) prenatal detection rate. Of the 62, 36 (58%) had right isomerism. Of the 51 prenatally diagnosed, 36 were live-born, 13 had fetal demise, and two underwent elective termination. Of the total 62, 43 had pulmonary outflow obstruction, 14 had systemic outflow obstruction, three had no outflow obstruction, and two had a common arterial trunk. However, between September 2004 and December 2019, 41 of 52 (79%) had pulmonary outflow obstruction, and between January 2000 and October 2021, 2 of 10 (20%) had pulmonary outflow obstruction (p = 001). We noted a statistically significant temporal change in the prevalence of pulmonary versus systemic outflow obstruction in those with isomeric situs and a functionally univentricular heart. Further, prenatal diagnosis exceeded 80% in the general population of Nevada.

Atypical Brain Asymmetry in Human Situs Inversus: Gut Feeling or Real Evidence?

The alignment of visceral and brain asymmetry observed in some vertebrate species raises the question of whether this association also exists in humans. While the visceral and brain systems may have developed asymmetry for different reasons, basic visceral left–right differentiation mechanisms could have been duplicated to establish brain asymmetry. We describe the main phenotypical anomalies and the general mechanism of left–right differentiation of vertebrate visceral and brain laterality. Next, we systematically review the available human studies that explored the prevalence of atypical behavioral and brain asymmetry in visceral situs anomalies, which almost exclusively involved participants with the mirrored visceral organization (situs inversus). The data show no direct link between human visceral and brain functional laterality as most participants with situs inversus show the typical population bias for handedness and brain functional asymmetry, although an increased prevalence of functional crowding may be present. At the same time, several independent studies present evidence for a possible relation between situs inversus and the gross morphological asymmetry of the brain torque with potential differences between subtypes of situs inversus with ciliary and non-ciliary etiologies.

The multisystem nature of isomerism: left isomerism complicated by Abernethy malformation and portopulmonary hypertension

Isomerism, also referred to as "heterotaxy" is a complex set of anatomic and functional perturbations. One of the most obvious manifestations of isomerism is the disturbance of organ arrangement, such that the thoracic organs are no longer asymmetric on the left and right. We report the case of a 14-year-old female in whom exercise-induced dyspnea led to a late diagnosis of left isomerism complicated by Abernethy malformation and portopulmonary hypertension. A comprehensive evaluation revealed two anatomic left lungs and hyparterial bronchi, bilateral left atria, an interrupted inferior caval vein with azygos continuation, multiple spleens, sinus node dysfunction, hepatic hypertrophy with focal nodular hyperplasia, and absence of the portal vein. Pulmonary vasodilator therapy was initiated resulting in clinical improvement. This case exhibits unique features including a late diagnosis of isomerism with Abernethy malformation and portopulmonary hypertension. The patient's presentation, medical workup, and future treatment emphasise the importance of multidisciplinary care in children with complex multisystem disease. We review the multiple cardiac and extracardiac manifestations of isomerism.

Comorbidities in situs inversus totalis: A hospital-based study

BACKGROUND AND OBJECTIVE

Few studies have assessed the comorbid diseases in situs inversus totalis (SIT) comprehensively. The aim of this study was to provide insight into the spectrum and prevalence of comorbidities in SIT.

METHODS

Children ≤18 years of age with SIT were enrolled in this retrospective observational study. Situs status and comorbidities were independently confirmed by two physicians, based on review of radiologic, ultrasonic examination, operative records, and case notes.

RESULTS

A total of 155 children (median age: 1.24 years; range: 1 day-17.8 years) confirmed to have SIT were recruited between January 2008 and December 2018. Associated conditions were diagnosed in 114 children (73.5%). Among them, 25 children (16.1%) had multiple anomalies affecting two or more organ systems. The most commonly associated conditions were congenital heart defects (n = 72, 46.5%) followed by primary ciliary dyskinesia (n = 19, 12.3%), renal disorders (n = 12, 7.7%), biliary atresia (n = 7, 4.5%), skeletal dysplasia (n = 8, 5.2%), and mental retardation (n = 4, 2.6%).

CONCLUSION

A substantial proportion of children with SIT have comorbidities affecting multiple systems, especially cardiovascular and respiratory abnormalities. Children with SIT warrant careful examination for the presence of congenital and acquired abnormalities.

Isomerism of the atrial appendages: morphology and terminology

BACKGROUND

Our aim is to identify the pathognomonic anatomical markers and the best terminology to describe the cardiac malformations associated with absent or multiple spleens, which are known as asplenia or polysplenia syndromes or isomerism.

MATERIALS AND METHODS

We have reviewed 65 hearts with isomerism of atrial appendages of the Anatomical Collections of Congenital Heart Disease, Institute of Pathological Anatomy of the University of Padua consisting of 1800 specimens. All the hearts were classified according to sequential segmental classification.

RESULTS

The incidence of isomerism was 3.6%. Of the total, 45 hearts with isomerism of right atrial appendages showed bilateral trilobed lungs, short bronchi, and absent spleen. The atrioventricular junction was univentricular in 49% of cases with a common atrioventricular valve in 91%. Pulmonary atresia and double outlet right ventricle were present in 40% and 47% of cases, respectively. Total anomalous pulmonary venous drainage and absent coronary sinus were always present. In 20 hearts with isomerism of left atrial appendages, bilateral bilobed lungs with long bilateral bronchi and multiple spleens were always found. The biventricular atrioventricular connection was present in 65% with a common valve in 30% of the hearts. The ventriculoarterial connection was concordant in 45% of cases, and aortic atresia and pulmonary atresia were both noted in 15% of each. An anomalous symmetric pulmonary venous drainage was observed in 65% of the hearts and interruption of inferior vena cava was found in 75% of cases.

CONCLUSIONS

We believe that the appropriate terminology is based on the symmetrical morphology of the atrial appendages. The absence of the coronary sinus and the total anomalous pulmonary venous drainage are the markers of isomerism of the right atrial appendages. Symmetric pulmonary venous drainage and interruption of inferior vena cava are the markers of isomerism of left atrial appendages. In recent years, thanks to the improvement of clinical diagnosis and of surgical techniques these patients have the possibility to survive to adult age.

Persistent right umbilical vein in isomerism

OBJECTIVE

Our objective was to evaluate the incidence of a persistent right umbilical vein in isomerism versus situs solitus.

METHODS

For this retrospective, observational, nonrandomized report, we identified fetuses with confirmed right umbilical veins from all patients referred for fetal echocardiography in Southern Nevada between January 2006 and January 2019.

RESULTS

For the period January 2006 to January 2019, we identified 89 fetuses with situs solitus and a right umbilical vein from 16 320 women undergoing prenatal cardiac evaluation, resulting in a right umbilical vein incidence of 0.5% in situs solitus. For the same period, we identified 36 fetuses with isomerism and confirmatory umbilical vein imaging. Of the 36, 15 (42%) had right umbilical veins. Of the 15, four of 11 (19%) had left isomerism, and 11 of 15 (73%) had right isomerism (P = .006).

CONCLUSIONS

A right umbilical vein is rare with situs solitus and common with isomerism. A right umbilical vein is more common in right isomerism than left isomerism and should alert the clinician to check for isomeric situs, especially right isomerism.

Timing of Fontan Completion in Children with Functionally Univentricular Hearts and Isomerism: The Impact of Age, Weight, and Pre-Fontan Arterial Oxygen Saturation

Isomerism, or heterotaxy, impacts morbidity and mortality after various stages of univentricular palliation. Timing of Fontan completing in these patients based on preoperative factors has not been investigated previously. The aim of this study was to determine the impact of preoperative factors on various outcomes including length of hospital stay and duration of chest tubes. A cross-sectional study was conducted. Patients with isomerism having undergone Fontan at the Children's Hospital of Wisconsin between 1998 and 2014 were identified. Preoperative, operative, and postoperative data were collected on these patients. Linear regression analysis was conducted to determine preoperative characteristics associated with various postoperative outcomes. Receiver operator curve analysis was also performed to determine the sensitivity and specificity of age and pre-Fontan arterial oxygen saturation in predicting increased length of hospitalization and increased duration of chest tubes. Younger age and lower pre-Fontan arterial oxygen saturation were associated with increased length of hospitalization while younger age, lower pre-Fontan arterial oxygen saturation, interrupted inferior caval vein, and worse pre-Fontan atrioventricular valve regurgitation were associated with increased length of chest tubes. Age, arterial oxygen saturation, pulmonary arteriovenous malformations, interruption of the inferior caval vein, and atrioventricular valve regurgitation should all be taken into consideration when timing Fontan completion in patients with isomerism. Arterial oxygen saturations between 82 and 84% with an approximate age of 3 years appear to be a time at which it is reasonable to consider Fontan in patients with isomerism.

A pilot study exploring the impact of cardiac medications on ciliary beat frequency: possible implications for clinical management

Background

Cilia are involved in several physiologic processes, and at least a single primary cilium can be found on nearly every cell in the human body. Various factors, such as pH, temperature, exposure to medications and toxins can impact ciliary function as is manifested by changes in the ciliary beat frequency. Those with ciliary dyskinesia may also have congenital cardiac malformations and may require care in a cardiac intensive care unit. This study investigates the effect on the ciliary beat frequency of medications frequently used in a cardiac intensive care unit.

Methods

The ciliated epithelial cells were obtained via nasal swab from a relatively healthy individual. These cells were cultured for 24 h. Video microscopy was then employed to determine the ciliary beat frequency at baseline and then at 15, 30, 60 and 90 min after exposure to either normal saline (control) or one of several medications. The ciliary beat frequency at each time point was then compared to the ciliary beat frequency at the same time point in the control sample as well as the baseline value for that particular sample.

Results

Epinephrine increased the ciliary beat frequency compared to the baseline and the controls up to 30 min and then subsequently led to a significant decrease in ciliary beat frequency at 90 min. On the one hand, norepinephrine, dexmedetomidine, procainamide, propranolol and enalapril all decreased ciliary beat frequency significantly throughout the 90-min observation period. On the other hand, Milrinone significantly increased the ciliary beat frequency throughout the observation period, while heparin had no impact on ciliary beat frequency.

Conclusions

The medications frequently used in cardiac intensive care unit impact ciliary function, with most being ciliodepressant. Further investigation is needed to determine the clinical impacts and whether these effects are exaggerated in those with ciliary dyskinesia.

Is isomerism a risk factor for intestinal volvulus?

INTRODUCTION

Isomerism, or heterotaxy syndrome, affects many organ systems anatomically and functionally. Intestinal malrotation is common in patients with isomerism. Despite a low reported risk of volvulus, some physicians perform routine screening and prophylactic Ladd procedures on asymptomatic patients with isomerism who are found to have intestinal malrotation. The primary aim of this study was to determine if isomerism is an independent risk factor for volvulus.

METHODS

Kid's Inpatient Database data from 1997 to 2012 was utilized for this study. Characteristics of admissions with and without isomerism were compared with a particular focus on intestinal malrotation, volvulus, and Ladd procedure. A logistic regression was conducted to determine independent risk factors for volvulus with respect to isomerism.

RESULTS

15,962,403 inpatient admissions were included in the analysis, of which 7970 (0.05%) patients had isomerism, and 6 patients (0.1%) developed volvulus. Isomerism was associated with a 52-fold increase in the odds of intestinal malrotation by univariate analysis. Of 251 with isomerism and intestinal malrotation, only 2.4% experienced volvulus. Logistic regression demonstrated that isomerism was not an independent risk factor for volvulus.

CONCLUSION

Isomerism is associated with an increased risk of intestinal malrotation but is not an independent risk factor for volvulus.

TYPE OF STUDY

Prognosis study.

LEVEL OF EVIDENCE

Level III.

Cardiopulmonary Exercise Testing in Fontan Patients With and Without Isomerism (Heterotaxy) as Compared to Patients With Primary Ciliary Dyskinesia and Subjects With Structurally Normal Hearts

Isomerism, also known as heterotaxy, is a clinical entity that impacts multiple organ systems both anatomically and functionally. The airways and lungs are involved in a great number of these patients, leading to increased sinopulmonary symptoms, increased need for oxygenation, and increased postoperative ventilatory support. Additionally, these patients often have congenital heart disease requiring Fontan palliation. What has not been previously described, and is the focus of this study, is the results of cardiopulmonary exercise testing in those who have undergone Fontan palliation with and without isomerism. We have now compared these finding with those from patients with primary ciliary dyskinesia, as many patients with isomerism have ciliary dyskinesia. We identified patients having the Fontan circulation with and without isomerism who had undergone cardiopulmonary exercise testing, comparing the findings from healthy individuals undergoing exercise, and a comparable number of individuals with primary ciliary dyskinesia but no congenital heart disease. We were able to include a total of 68 patients in our study, with 17 in each of the four groups. Cardiopulmonary exercise testing yielded the best results in healthy patients. All patients with the Fontan circulation demonstrated mixed pulmonary disease, although those with isomerism had greater FVC and FEV1. Exercise times did not differ, although peak consumption of oxygen was greater in those with isomerism. Those with ciliary dyskinesia had only obstructive pulmonary disease and had the lowest FEF25-75 between all groups. Those with isomerism had a lesser degree of obstructive pulmonary disease when compared to those with primary ciliary dyskinesia. Patients with the Fontan circulation with and without isomerism have relatively subtle differences in their cardiopulmonary exercise testing, with both groups demonstrating restrictive lung disease. In regard to obstructive lung disease, those with isomerism tend to be more similar to the patients with primary ciliary dyskinesia than those with the Fontan circulation but without isomerism. The results are likely limited by selection bias and highlight the need for multicentric efforts to characterize cardiopulmonary exercise testing in those patients with pulmonary isomerism.

Characteristics of Hospitalizations for the Glenn Procedure in Those With Isomerism Compared to Those Without

Isomerism, also known as heterotaxy, is a unique clinical entity in which there are mirror imaged findings in the thoracic. In the abdomen, the arrangement of organs can be random. The anatomic findings also have functional consequences. Isomerism has been known to increase morbidity and mortality in those with functionally univentricular hearts. The aim of this study was to determine the impact of isomerism on the Glenn hospitalization. Data from the 1997 to 2012 Kids' Inpatient Database were utilized for this cross-sectional study. Admissions during which a Glenn procedure was done were identified. Next, these admissions were separated into those with and without isomerism. Admission characteristics were then compared in a univariate fashion as well as by regression analysis. Length of hospitalization, cost of hospitalization, extracorporeal membrane oxygenation, and inpatient mortality were the outcomes of interest. A total of 4959 admissions with a Glenn procedure were identified. Of these, 450 were associated with isomerism. The median age at which the Glenn procedure was done was 10 and 13 months in those without and with isomerism, respectively. Neither univariate nor regression analysis demonstrated any significant difference in length of hospitalization, cost of hospitalization, need for extracorporeal membrane oxygenation, and inpatient mortality between those with and without isomerism. Isomerism does not impact the characteristics of the Glenn hospitalization. Those with isomerism did tend to be older when they underwent the Glenn procedure.

Bodily isomerism is an independent risk factor for pulmonary hypertension in adults with congenital heart disease

INTRODUCTION

Bodily isomerism, or heterotaxy is a unique entity on which there is mirror imagery in various organ systems, leading to a deviation from the normal lateral arrangements of the viscera. Adults with such isomerism and associated congenital malformations of the heart are now reaching adulthood and developing long-term complications. This study investigates the prevalence and characteristics of pulmonary hypertension in adults with isomerism.

METHODS

The 2012 iteration of the Nationwide Inpatient Sample was utilized and patients were identified as having or not having bodily isomerism and having or not having pulmonary hypertension. Univariate analysis utilizing Chi-square tabulation was done to assess characteristics associated with pulmonary hypertension. Next, a multivariate analysis was done on all patients to identify predictors of pulmonary hypertension followed by a multivariate analysis of patients with only isomerism to identify predictors of pulmonary hypertension specific to this subset.

RESULTS

A total of 6,907,109 admissions were included in the analysis. Of these, 861 had isomerism (0.01%). Of those with isomerism, 5.6% were found to have pulmonary hypertension. When all patients were included in the multivariate analysis, isomerism was found to be an independent risk factor for pulmonary hypertension with an odds ratio of approximately 1.79. When only patients with isomerism were included in the multivariate analysis, advanced age, obesity, and history of anomalous pulmonary venous connection were independent risk factors of pulmonary hypertension.

CONCLUSION

Pulmonary hypertension is more common in those with isomerism, with isomerism being an independent risk factor for pulmonary hypertension. The prevalence of pulmonary hypertension is 5.6% in the setting of isomerism. Independent risk factors for pulmonary hypertension in patients with isomerism include age, obesity, and history of anomalous pulmonary venous connection.

When the right (Drug) should be left: Prenatal drug exposure and heterotaxy syndrome

BACKGROUND

Recent studies reported an association between prenatal propylthiouracil exposure and birth defects, including abnormal arrangement across the left-right body axis, suggesting an association with heterotaxy syndrome.

METHODS

This case-control and case-finding study used data from 1981 to 2013 from the EUROCAT birth defect registry in the Northern Netherlands. First, we explored prenatal exposures in heterotaxy syndrome (cases) and Down syndrome (controls). Second, we describe the specific birth defects in offspring of mothers using propylthiouracil (PTU) prenatally.

RESULTS

A total of 66 cases with heterotaxy syndrome (incidence 12.1 per 100,000 pregnancies) and 783 controls with Down syndrome (143.3 per 100,000 pregnancies) were studied. No differences in intoxication use during pregnancy were found between cases and controls, including smoking (28.0% vs. 22.7%; p = 0.40), alcohol (14.0% vs. 26.9%; p = 0.052), and recreational drugs (0 vs. 0.3%; p = 1.00). We found an association between heterotaxy syndrome and prenatal drug exposure to follitropin-alfa (5.6% vs. 1.1%; p = 0.04), and drugs used in nicotine dependence (3.7% vs. 0.2%; p = 0.02). Five mothers used PTU during pregnancy and gave birth to a child with trisomy 18, renal abnormalities, or hypospadias and cardiac defects.

CONCLUSION

This study identified follitropin-alfa and drugs used in nicotine dependence as possible teratogens of heterotaxy syndrome. Our data suggest the possibility that there is an increased risk of birth defects (including renal, urological, and cardiac abnormalities) in children born among mothers taking PTU prenatally, but not for heterotaxy syndrome. Birth Defects Research (Part A) 106:573-579, 2016. © 2016 Wiley Periodicals, Inc.

Fontan Outcomes and Pulmonary Blood Flow at Birth

We previously noted, in a small group of post-Fontan patients, a possible association between hepatic fibrosis scores and the status of pulmonary blood flow at birth. To further explore this observation, we examined data from all Fontan patients seen in our center from July 2010 to March 2015. We identified 200 patients for analysis. Of the 200 patients, 56 underwent transvenous-hepatic biopsy. Of the 200 patients, 13 (6.5%) had protein-losing enteropathy. We divided both the 56 biopsy patients and the entire cohort of 200 patients into 4 groups: (1) unobstructed pulmonary blood flow at birth with functional left ventricles, (2) unobstructed pulmonary blood flow at birth with functional right ventricles, (3) obstructed pulmonary blood flow at birth with functional left ventricles, and (4) obstructed pulmonary blood flow at birth with functional right ventricles. Analysis of the 56 liver-biopsy patient groups showed median hepatic total-fibrosis scores for the 4 groups of 2 (0-6), 2 (0-8), 3 (2-6), and 4 (1-8), respectively, with statistical significance between groups 4 and 1 (p = 0.031). For the entire cohort of 200 patients, we analyzed the incidence of protein-losing enteropathy for each of the four groups and found protein-losing enteropathy percent occurrences of 0, 2.9, 8.8, and 16.1, respectively, with statistical significance between groups 4 and 2 (p = 0.031) and between groups 4 and 1 (p = 0.025). A history of obstructed pulmonary blood flow at birth, coupled with a functional right ventricle, may predict a poorer long-term Fontan outcome.

Thrombocytosis in the Setting of Isomerism and a Functionally Univentricular Heart

Introduction

Bodily isomerism, also known as heterotaxy, is a unique entity in which there is mirror imagery in various organ systems. Those with isomerism will often have congenital malformations of the heart requiring functionally univentricular palliation. Anecdotally, thrombocytosis has been noted with higher frequency in patients with isomerism. This study aimed to determine the prevalence of thrombocytosis at different stages and identify independent predictors of thrombocytosis.

Methods

We identified patients with isomerism and a functionally univentricular heart who received care at our institution between January 1998 and January 2014. Clinical data regarding these patients was collected via chart review. Platelet counts were collected before initial surgical palliation, the day prior to second surgical palliation, and the day prior to the third surgical palliation. Platelet counts from the first postoperative day following all three surgical palliations was also collected. Mean platelet counts were compared between consecutive stages as well as to the initial platelet count. The frequency of thrombocytosis was also calculated at each point with a binomial logistic regression conducted to determine independent risk factors of thrombocytosis at each time point.

Results

A total of 57 patients were included in the analysis. The mean platelet count before initial surgical palliation was 349.21 x 10⁹/L and decreased with age. Thrombocytosis was noted in 15.8% prior to initial surgical palliation and 23.6% prior to second surgical palliation. Thrombocytosis was no longer noted after second surgical palliation. No independent risk factors for thrombocytosis were identified.

Conclusion

Thrombocytosis is not infrequent during the first year of life in those with isomerism. It is important to be vigilant of platelet counts in this population as thrombocytosis may lead to increased thromboembolic events, particularly in the setting of a Blalock-Taussig shunt. Thrombocytosis nearly always resolves after the second surgical palliation.