Cross sectional echocardiographic identification of hypoplastic left heart syndrome and differentiation from other causes of right ventricular overload.

To identify the echocardiographic features that can be used to distinguish between hypoplastic left heart syndrome and other causes of right ventricular overload in the sick neonate cross sectional echocardiographic studies of 10 neonates with hypoplastic left heart syndrome were analysed and compared with those in 15 neonates with other causes of right ventricular overload and 15 normal controls. Left ventricular and right ventricular cavity dimensions and the shape and size of the mitral valve annulus and aortic root were recorded and presented both as absolute values (mm) and corrected for body surface area (mm/m2). Logistic regression was used to produce a classification rule to estimate the probability of a neonate having hypoplastic left heart syndrome. The diameter of the mitral valve annulus was the single most discriminative variable. There was, however, considerable overlap of all the calculated features between neonates with hypoplastic left heart syndrome and those with other causes of right ventricular overload. The diagnosis of hypoplastic left heart syndrome should not be based on any one single echocardiographic feature but the general appearance of abnormal left heart valves, small cavity dimensions, and the size of the mitral valve annulus.     

Cross sectional echocardiographic identification of hypoplastic left heart syndrome and differentiation from other causes of right ventricular overload

To identify the echocardiographic features that can be used to distinguish between hypoplastic left heart syndrome and other causes of right ventricular overload in the sick neonate cross sectional echocardiographic studies of 10 neonates with hypoplastic left heart syndrome were analysed and compared with those in 15 neonates with other causes of right ventricular overload and 15 normal controls. Left ventricular and right ventricular cavity dimensions and the shape and size of the mitral valve annulus and aortic root were recorded and presented both as absolute values (mm) and corrected for body surface area (mm/m2). Logistic regression was used to produce a classification rule to estimate the probability of a neonate having hypoplastic left heart syndrome. The diameter of the mitral valve annulus was the single most discriminative variable. There was, however, considerable overlap of all the calculated features between neonates with hypoplastic left heart syndrome and those with other causes of right ventricular overload. The diagnosis of hypoplastic left heart syndrome should not be based on any one single echocardiographic feature but the general appearance of abnormal left heart valves, small cavity dimensions, and the size of the mitral valve annulus.     

Hypoplastic left heart syndrome and 45X karyotype.

A review of 63 patients with 45X karyotype (Turner's syndrome) admitted to a hospital from 1972 to 1985 showed that 20 (32%) had one or more major cardiac malformations (mostly coarctation and aortic stenosis). Four (20%) died in the neonatal. One infant had mitral stenosis and severe aortic stenosis and died at the age of 35 days. The three (15%) other patients who died had a typical hypoplastic left heart syndrome, with an atretic aortic valve in two and pinpoint aortic valve in one. Turner's syndrome was clinically suspected in three of the cases. One of these had mosaicism (46XX,45X) the others had a 45X pattern. During the same period (1972-85) 39 patients (14 girls and 25 boys) were admitted with diagnosis of hypoplastic left heart syndrome. Three (21.4%) girls had a 45X karyotype. The high incidence of hypoplastic left heart syndrome in Turner's syndrome and of Turner's syndrome in girls with hypoplastic left heart syndrome suggests that hypoplastic left heart syndrome can be another expression of the 45X karyotype.     

Hypoplastic left heart syndrome and 45X karyotype

A review of 63 patients with 45X karyotype (Turner's syndrome) admitted to a hospital from 1972 to 1985 showed that 20 (32%) had one or more major cardiac malformations (mostly coarctation and aortic stenosis). Four (20%) died in the neonatal. One infant had mitral stenosis and severe aortic stenosis and died at the age of 35 days. The three (15%) other patients who died had a typical hypoplastic left heart syndrome, with an atretic aortic valve in two and pinpoint aortic valve in one. Turner's syndrome was clinically suspected in three of the cases. One of these had mosaicism (46XX,45X) the others had a 45X pattern. During the same period (1972-85) 39 patients (14 girls and 25 boys) were admitted with diagnosis of hypoplastic left heart syndrome. Three (21.4%) girls had a 45X karyotype. The high incidence of hypoplastic left heart syndrome in Turner's syndrome and of Turner's syndrome in girls with hypoplastic left heart syndrome suggests that hypoplastic left heart syndrome can be another expression of the 45X karyotype.     

Morphologic determinants of coronary blood flow in the hypoplastic left heart syndrome

The diameters of the ascending aorta, coronary ostia, and proximal coronary arteries were measured in autopsy specimens from 51 infants with hypoplastic left heart syndrome and 18 normal infant heart specimens. Standard cross sections were prepared from 35 of the hypoplastic left heart syndrome hearts, and histologic indices of myocardial viability and fibrosis were determined. The diameters of the coronary arteries and ostia in hypoplastic left heart syndrome were not different from the values in control specimens. Little fibrosis was found but extensive myocardial necrosis was present. The degree of fibrosis and necrosis did not correlate significantly with any of the arterial or ostial diameters. The extent of myocardial preservation in the hypoplastic left heart syndrome, which may substantially limit the success of surgical palliation, cannot be predicted from these morphologic measurements. The observed myocardial damage appeared to be acquired postnatally, implying that early vigorous treatment of these infants may be necessary to preserve myocardial function.     

Fetal hydrops in a newborn with hypoplastic left heart syndrome: tricuspid valve "stopper"

Fetal hydrops in a newborn infant with hypoplastic left heart syndrome led to the discovery of tricuspid stenosis and insufficiency from an unusual malformation of the right venous valve of the embryonic sinus venosus. This unfortunate combination of lesions precluded surgical palliation for the hypoplastic left heart.     

Hybrid palliation in hypoplastic left heart syndrome

PURPOSE OF REVIEW: Despite progressive improvement in surgical results, hypoplastic left heart syndrome remains one of the congenital heart abnormalities with the greatest morbidity and mortality. Hybrid approaches to management, combining surgical and interventional catheterization procedures, have been introduced to minimize exposure to cardiopulmonary bypass, and improve outcomes for these high-risk infants. RECENT FINDINGS: First-stage palliation of hypoplastic left heart syndrome has been performed as a hybrid procedure combining surgical pulmonary artery banding with catheterization stenting of the ductus arteriosus and balloon atrial septostomy, especially in high-risk patients. Additionally, several centers have performed second-stage palliation - bidirectional Glenn or hemi-Fontan procedures - in a manner that allows the subsequent 'Fontan' procedure to be completed in the catheterization laboratory with a covered stent. SUMMARY: These innovative procedures offer the potential of an alternative management strategy for hypoplastic left heart syndrome. They have been applied to a very limited number of patients and long-term results are not available. Their role in management of hypoplastic left heart syndrome remains to be defined, especially as results of conventional surgical management continue to improve.     

Premature closure of the foramen ovale associated with aortic stenosis, left ventricular dilation with thrombus, and early mortality

Premature foramen ovale (FO) closure has been postulated as a cause of hypoplastic left heart syndrome. We suggest that premature FO closure is also associated with left ventricular (LV) dilation and LV thrombus formation, and that FO closure in patients with aortic stenosis and LV dilation is a secondary event that occurs later in gestation than that seen with the hypoplastic left heart.     

Informed consent, bioethical equipoise, and hypoplastic left heart syndrome

In utero diagnosis of complex progressive cardiac disease such as hypoplastic left heart syndrome presents a novel opportunity for antepartum, intrapartum, and neonatal management. The clinical possibilities and potential for differing outcomes challenge the mother-foetus dyad with regard to informed consent. Previous studies reveal that rates of termination of pregnancy for foetuses with hypoplastic left heart syndrome vary widely in the United States and Europe, leading us to surmise that informed consent may be practised differently. The purpose of this paper is to review the ethical considerations and physician responsibilities of informed consent as they relate to prenatal and postnatal patients with hypoplastic left heart syndrome. Special consideration is paid to the informed consent process as practised by the obstetrician, perinatologist, paediatric cardiologist, and paediatric cardiac surgeon as it relates to termination of pregnancy, comfort care, and surgical palliation. We will argue that informed consent as it relates to hypoplastic left heart syndrome is far from standardised and that there exists a state of bioethical equipoise concerning the extent and limits of its application in the current clinical setting.     

Fistulous communications with the coronary arteries in the setting of hypoplastic ventricles

Neonates born with hypoplastic left heart syndrome now have a remarkably improved prognosis compared with the situation existing before the development of the Norwood sequence of operative procedures. Some of those born with hypoplastic right ventricles in the setting of pulmonary atresia with an intact ventricular septum, however, still have a relatively poor prognosis. In part this reflects the presence of fistulous communication between the cavity of the right hypoplastic right ventricle and the coronary arterial tree. Such fistulous communications are now increasingly recognised as being important in the setting of hypoplastic left heart syndrome. In this brief review, we describe the anatomy of the communications. Those found with hypoplastic right ventricles are seen most frequently when the cavity of the ventricle effectively represents only the inlet, this in turn reflecting mural overgrowth of the apical trabecular and outlet components during foetal development. This almost certainly reflects an earlier appearance of the pulmonary valvar lesion that promotes the cavitary hypoplasia. In those with hypoplastic left ventricles, the key feature differentiating those with fistulous communications is the presence of a patent mitral valve, since the left ventricle is typically no more than a virtual slit in postero-inferior ventricular wall in the setting of mitral valvar atresia or absence of the left atrioventricular connection.     

Long-term management of patients with hypoplastic left heart syndrome: the diagnostic approach at All Children's Hospital

Improved survival in children with hypoplastic left heart syndrome has created a sub-population of children and young adults who are living with functionally univentricular physiology. Routine surveillance with comprehensive screening for structural cardiac disease, functional cardiac disease, arrhythmias, thromboembolic disease, and associated dysfunction of end organs is important. Future directives will better define the plans of care for routine surveillance in patients with hypoplastic left heart syndrome.     

Hypoplastic left heart syndrome: experience with palliative surgery

Aortic atresia is a form of hypoplastic left heart syndrome always complicated by associated severe hypoplasia of the ascending aorta and various degrees of mitral valve and left ventricular hypoplasia. At present it is a universally fatal lesion in early infancy. This is a report of a new palliative procedure for hypoplastic left heart syndrome that has resul;ed in early ongoing survival of two infants with aortic atresia. On the basis of experience with a third patient, an operation for future physiologic correction is proposed.     

Hypoplastic left heart with complete transposition of the great arteries.

A male newborn infant with hypoplastic left heart and transposition of the great arteries died on the second day of life. The haemodynamic consequences of this malformation are considerably different from those of ordinary hypoplastic left heart syndrome because of pulmonary rather than aortic atresia. In the absence of cross sectional echocardiographic equipment, cardiac catheterisation with angiography is necessary to delineate the anatomical picture. These two conditions have not apparently been reported before in association.     

Hypoplastic left heart syndrome: is echocardiography accurate enough to guide surgical palliation?

Two-dimensional echocardiography can diagnose hypoplastic left heart syndrome. However, with the advent of the possibility of palliative open heart surgery, complete anatomic diagnosis is necessary. The anatomic findings of 15 neonates with hypoplastic left heart syndrome (age 1 to 10 days, mean 4.1) who had two-dimensional Doppler echocardiographic studies were compared with the results obtained by angiography (6 cases), surgery (11 cases) and autopsy (8 cases). Complete two-dimensional echocardiographic examination of the aortic arch, pulmonary and systemic venous return, atrial septum, ductus arteriosus and proximal coronary arteries was possible in all 15 neonates and correctly diagnosed hypoplastic left heart syndrome in each. Anatomic two-dimensional echocardiographic assessment was accurate in 13 (86%) of the 15 neonates and there were no false positive results. Undiagnosed associated abnormalities were hypoplasia of a left pulmonary artery in one patient and left superior vena cava in another. Accurate quantitation of the size of the tricuspid valve anulus, ascending aorta, pulmonary anulus and right and left pulmonary arteries was possible. Doppler examination was performed in seven patients and confirmed retrograde aortic arch flow and right to left systolic shunting in the patent ductus arteriosus. In selected neonates, surgical palliation can be attempted without angiography.     

Percutaneous transcatheter occlusion of left atrioventricular valve in a patient with single ventricle and severe atrioventricular valve regurgitation

Many patients with single ventricle physiology suffer from atrioventricular valve (AVV) regurgitation which may worsen their cardiac function and cause symptoms. It has been postulated that elimination of the nondominant hypoplastic AVV regurgitation, might improve the clinical status in patients post-Fontan surgery. We describe a case of hypoplastic left heart variant, post Fontan surgery who had severe left AVV regurgitation and underwent percutaneous transcatheter occlusion of the hypoplastic left AVV, using a VSD occluder device. At 3 months post procedure, the patient is improved. Transcatheter closure of a regurgitant hypoplastic AVV in a patient with single ventricle helps to improve the patient's cardiac function and clinical status.     

Echocardiographic spectrum of the hypoplastic left heart syndrome: A clinicopathologic correlation in 19 newborns

Ultrasonic studies were performed in 19 neonates with the hypoplastic left heart syndrome whose diagnosis was confirmed at angiography or autopsy, or both. The patients were classified in two echocardiographic groups: Group I, 10 infants whose ventricular septum could be recorded, and Group II, 9 infants whose septum could not be recorded. The findings in these groups were compared with those in 60 neonates without congenital heart disease also studied with ultrasound. Two additional neonates who presented with signs of shock were also studied.The diagnostic echocardiographic features of hypoplastic left heart syndrome were: (1) a left ventricular end-diastolic dimension of less than 9 mm; (2) an aortic root diameter of less than 6 mm; (3) a ratio of left ventricular end-diastolic to right ventricular end-diastolic dimension of less than 0.6; and (4) a mitral valve echo that is absent or greatly distorted and of small amplitude. These echocardiographic criteria differed significantly from findings in the normal group (P < 0.01). Echocardiography proved valuable in neonates with shock. It is a safe, reliable technique that can be used to delineate the intracardiac anatomy in sick neonates with the hypoplastic left heart syndrome.     

Experimental production of hypoplastic left heart syndrome in the chick embryo

The hypothesis is examined that hemodynamic alterations at the site of the primordial mitral valve may induce malformations that simulate the clinical findings of hypoplastic left heart syndrome. Surgical placement of a nylon device, approximately 90 μ in diameter, into the region of the left atrioventricular (A-V) canal was accomplished in 192 embryos (Hamburger-Hamilton stages 23 to 25). Thirty-nine pairs of experimental and control embryos survived more than 12 days. Twenty-six experimental embryos exhibited various malformations: hypoplastic left atrium and ventricle, mitral valvular atresia, aortic valvular stenosis and tubular hypoplasia of the aorta and brachlocephalic vessels. These findings reemphasize the probable morphogenetic role of blood flow pathways. The findings further implicate involvement of the left A-V canal as well as premature closing of foramen ovale and aortic valvular abnormalities in the hypoplastic left heart syndrome.     

Fetal interventions for structural heart disease

Fetal cardiac intervention (FCI) offers the potential to alter in utero anatomy and physiology. For aortic stenosis with evolving hypoplastic left heart syndrome and pulmonary atresia with intact ventricular septum with evolving hypoplastic right heart syndrome, FCI may result in maintenance of a biventricular circulation, thus avoiding single‐ventricle palliation and its attendant complications. In the case of hypoplastic left heart syndrome with intact atrial septum, FCI may ameliorate in utero pathophysiology and portend a more favorable postnatal prognosis. In all cases, a detailed fetal echocardiographic assessment to identify the appropriate FCI candidate is essential. This article reviews the three aforementioned lesions for which FCI can be considered. The pathophysiology and rationale for intervention, echocardiographic assessment, patient selection criteria, and outcomes for each lesion will be reviewed. A primary focus will be the echocardiographic evaluation of each lesion.     

Pattern of pulmonary venous blood flow in the hypoplastic left heart syndrome in the fetus

OBJECTIVE: To determine whether restriction at the atrial septum in the newborn with hypoplastic left heart syndrome can be predicted accurately by examining the pattern of pulmonary venous flow in the fetus. A restrictive atrial septum can contribute to haemodynamic instability before surgery for this lesion and has been associated with an increased mortality. DESIGN: Pulmonary venous pulsed Doppler tracings were compared between fetuses with hypoplastic left heart syndrome and controls. The size of the atrial septal defect on the postnatal echocardiogram was graded according to the degree of restriction. Pulsed Doppler tracings of pulmonary venous blood flow were obtained in 18 fetuses with left atrial outflow atresia and compared with 77 controls, adjusted for gestational age. Postnatal echocardiograms were available for analysis in 13 of 18 neonates. SETTING: A tertiary referral centre for fetal cardiology and paediatric cardiac surgery. RESULTS: Fetuses with hypoplastic left heart syndrome were different from controls in all pulmonary vein indices measured. As assessed from the postnatal echocardiogram, there were seven fetuses with a restrictive atrial septum. In these fetuses, the systolic flow velocity (p < 0.01), S/D ratio (p < 0.01), and peak reversal wave (p < 0.001) in the pulmonary vein tracing showed a good correlation with the degree of restriction. CONCLUSIONS: The Doppler pattern of pulmonary venous flow in the fetus with hypoplastic left heart syndrome appears to be a reliable predictor of restriction of the atrial septum in the neonate. This may help in the immediate post-delivery management of these infants before surgery.     

Aortic morphometry and microcephaly in hypoplastic left heart syndrome

Microcephaly is a marker of abnormal fetal cerebral development, and a known risk factor for cognitive dysfunction. Patients with hypoplastic left heart syndrome have been found to have an increased incidence of abnormal neurodevelopmental outcomes. We hypothesized that reduced cerebral blood flow from the diminutive ascending aorta and transverse aortic arch in the setting of hypoplastic left heart syndrome may influence fetal growth of the brain. The purpose of our study, therefore, was to define the prevalence of microcephaly in full-term infants with hypoplastic left heart syndrome, and to investigate potential cardiac risk factors for microcephaly. We carried out a retrospective review of full-term neonates with hypoplastic left heart syndrome. Eligible patients had documented indexes of birth weight, and measurements of length, and head circumference, as well as adequate echocardiographic images for measurement of the diameters of the ascending aorta and transverse aortic arch. We used logistic regression for analysis of the data. A total of 129 neonates met the criteria for inclusion, with 15 (12%) proving to have microcephaly. The sizes of their heads were disproportionately smaller than their weights (p less than 0.001) and lengths (p less than 0.001) at birth. Microcephaly was associated with lower birth weight (p less than 0.001), lower birth length (p equal to 0.007), and a smaller diameter of the ascending aorta (p equal to 0.034), but not a smaller transverse aortic arch (p equal to 0.619), or aortic atresia (p equal to 0.969). We conclude that microcephaly was common in this cohort of neonates with hypoplastic left heart syndrome, with the size of the head being disproportionately smaller than weight and length at birth. Microcephaly was associated with a small ascending aorta, but not a small transverse aortic arch. Impairment of somatic growth may be an additional factor in the development of microcephaly in these neonates.