Andrew M Taylor

University College London | UCL · Institute of Cardiovascular Science

Tetralogy of Fallot (TOF) is the most common form of cyanotic congenital heart disease, occurring in 1 in 3600 live births. Complete repair of TOF was devised over 50 years ago (first reported by Lillehei in 1954) and can result in complete intracardiac repair in early infancy. There are excellent short- and medium-term survival rates, and 25-year...

Cardiac magnetic resonance (CMR) has increasingly replaced diagnostic cardiac catheterization as a method of assessing cardiac anatomy, measuring blood flow, and quantifying ventricular function. Nevertheless, interventional cardiac catheterization is a growth area for providing treatments for congenital heart disease. Furthermore, diagnostic cardi...

Background Greater body mass index is associated with cardiovascular remodeling in adolescents. However, body mass index cannot differentiate between adipose and nonadipose tissues. We examined how visceral and subcutaneous adipose tissue are linked with markers of early cardiovascular remodeling, independently from nonadipose tissue. Methods and...

It has been over 20 years since the first-in-human PPVI procedure by Phillip Bonhoeffer et al., the possibilities for transcatheter heart valve replacement have boomed and many lives have been saved or enhanced. The transcatheter valve market has opened to dozens of solutions which are collectively able to treat any of the four human heart valves,...

This study aimed to investigate the effect of pulmonary regurgitation (PR) on left ventricular ventriculo–arterial (VA) coupling in patients with repaired tetralogy of Fallot (ToF). It was hypothesised that increasing PR severity results in a smaller forward compression wave (FCW) peak in the aortic wave intensity, because of right-to-left ventricu...

This chapter looks at the complex scenario of univentricular (Fontan) circulation, especially from the perspective of ventriculoarterial coupling, i.e., the complex relationship between the single systemic ventricle and the remainder of the circulation following surgical repair. Different methodologies can be employed to study this complex hemodyna...

Objectives: Patient-specific multiscale modeling simulates virtual surgeries of the Fontan procedure using three different graft options. Predictive modeling details post-operative outcomes that can help inform clinical decision support. Methods: Six patients underwent preoperative cardiac magnetic resonance imaging and catheterization. Virtual sur...

One of the main sources of error in multi-atlas segmentation propagation approaches comes from the use of atlas databases that are morphologically dissimilar to the target image. In this work, we exploit the segmentation errors associated with poor atlas selection to build a computer aided diagnosis (CAD) system for pathological classification in p...

Background Blood-based biomarkers reflecting different components of cardiovascular pathophysiology are now used increasingly in patients with Fontan circulation due to univentricular congenital heart disease. Feeding alters haemodynamics significantly and, thus, may affect biomarker levels. As the haemodynamic responses to a meal differ between Fo...

In univentricular (Fontan) physiology, peripheral and splanchnic vascular tone may be raised to counteract reduced cardiac output (CO) and elevated central venous pressure, and thus maintain vital organ perfusion. This could negatively affect the normal cardiovascular response to food ingestion, where mesenteric vasodilation and a concurrent rise i...

Transcatheter aortic valve implantation (TAVI) still presents complications: paravalvular leakage (PVL) and onset of conduction abnormalities leading to permanent pacemaker implantation. Our aim was testing a validated patient-specific computational framework for prediction of TAVI outcomes and possible complications. Twenty-eight TAVI patients (14...

Neonates with CHD are at increased risk of developing necrotising enterocolitis due to mesenteric hypoperfusion. Necrotising enterocolitis results in repeated feed interruptions contributing to poor growth during the early post-operative phase. Poor weight gain and longer hospital stay are risk factors for death in neonates with CHD. Abdominal radi...

(Abstracted from Prenat Diagn 2019;39:818–829) Investigation after birth of fetal anomalies detected on prenatal ultrasound (US) is important, particularly after termination of pregnancy or fetal or perinatal loss, in terms of significant implications for genetic counseling, subsequent reproductive choices, and other family members. Confirmation of...

Computed tomography (CT) has a well-established diagnostic role in the assessment of coronary arteries in adults. However, its application in a pediatric setting is still limited and often impaired by several technical issues, such as high heart rates, poor patient cooperation, and radiation dose exposure. Nonetheless, CT is becoming crucial in the...

Background: Left ventricular hypertrophy (LVH) is a major risk factor for cardiovascular disease, including heart failure. Although linked to obesity and hypertension, its pathogenesis is multifactorial. Blunted postprandial sympathetic regulation of gut blood flow has been observed in overweight animals and suggested as a promotor of hypertension...

Superior cavopulmonary circulation (SCPC) can be achieved by either the Hemi-Fontan (hF) or Bidirectional Glenn (bG) connection. Debate remains as to which results in best hemodynamic results. Adopting patient-specific multiscale computational modeling, we examined both the local dynamics and global physiology to determine if surgical choice can le...

In light of growing interest for three-dimensional printing technology in the cardiovascular community, this study focused on exploring the possibilities of providing training for cardiovascular three-dimensional printing in the context of a relevant international congress and providing considerations on the delivery of such courses. As a second ob...

Objective: To determine the additional yield from autopsy following prenatal ultrasound and post-mortem magnetic resonance imaging (PMMR) for structural abnormalities. Method: PMMR was performed on consecutive fetuses over a 6-year period. Prenatal ultrasound and PMMR findings were categorised as concordant, partially concordant or discordant fi...

Cross-sectional imaging (cardiovascular MRI and CT) has become a crucial component in the diagnostic pathway in patients with congenital heart disease over the last decade. Their use compliments echocardiography and, for many cases, has superseded the use of diagnostic cardiac catheterisation. Though cardiovascular MRI is still the main form of cro...

Background Marfan syndrome is a multi-systemic disorder characterized by progressive aortic dilation. Follow-up imaging is performed to monitor aortic dimensions, traditionally assessed by 2D diameter measurements, which cannot capture complex aortic shape variations. Statistical shape analysis is a novel technique that allows for a more comprehens...

Medical imaging is an integral part of anatomical and function assessment of congenital heart disease (CHD), with cardiovascular magnetic resonance (CMR) imaging and computed tomography (CT) imaging having become essential in the diagnosis and management of both paediatric and adult CHD. These two modalities have respective advantages, but overall...

Three-dimensional (3D) printing technology in congenital cardiology and cardiac surgery has experienced a rapid development over the last decade. In presence of complex cardiac and extra-cardiac anatomies, the creation of a physical, patient-specific model is attractive to most clinicians. However, at the present time, there is still a lack of stro...

Sudden cardiac death (SCD) is a catastrophic complication of many cardiac conditions often occurring without warning. In these cases, a post-mortem examination is required to elucidate the cause of death and is regarded as the ‘gold standard’. However, in circumstances of certain religious/cultural beliefs and advanced body decomposition an alterna...

Patient-specific computational models are an established tool to support device development and test under clinically relevant boundary conditions. Potentially, such models could be used to aid the clinical decision-making process for percutaneous valve selection; however, their adoption in clinical practice is still limited to individual cases. To...

OBJECTIVE: Modeling of single-ventricle circulations has yielded important insights into their unique flow dynamics and physiology. Here we translated a state-of-the-art mathematical model into a patient-specific clinical decision support interactive Web-based simulation tool and show validation for all 3 stages of single-ventricular palliation. ME...

Background: Although stillbirth is a significant health problem worldwide, the definitive cause of death remains elusive in many cases, despite detailed autopsy. In this study of partly explained and unexplained stillbirths, we used next-generation sequencing to examine an extended panel of 35 candidate genes known to be associated with ion channe...

Patient-specific computational models have been extensively developed over the last decades and applied to investigate a wide range of cardiovascular problems. However, translation of these technologies into clinical applications, such as planning of medical procedures, has been limited to a few single case reports. Hence, the use of patient-specif...

Personalised 3D modelling of the heart is of increasing interest in order to better characterise pathologies and predict evolution. The personalisation consists in estimating the parameter values of an electromechanical model in order to reproduce the observed cardiac motion. However, the number of parameters in these models can be high and their e...

Objective: Modeling of single-ventricle circulations has yielded important insights into their unique flow dynamics and physiology. Here we translated a state-of-the-art mathematical model into a patient-specific clinical decision support interactive Web-based simulation tool and show validation for all 3 stages of single-ventricular palliation....

Differences between hearts of crocodilians and those of mammals and birds are only partly understood because there is no standardised approach and terminology for describing cardiac structure. Whereas most reptiles have an undivided ventricle, crocodilians have a fully septated ventricle. Their hearts, therefore, are more readily comparable with th...

Objective This study sought to explore the diagnostic insight of cardiovascular magnetic resonance (CMR)-derived wave intensity analysis to better study systolic dysfunction in young patients with chronic diastolic dysfunction and preserved ejection fraction (EF), comparing it against other echocardiographic and CMR parameters. Background Evaluati...

This pilot study aimed to assess the impact of using patient-specific three-dimensional (3D) models of congenital heart disease (CHD) during consultations with adolescent patients. Adolescent CHD patients (n = 20, age 15–18 years, 15 male) were asked to complete two questionnaires during a cardiology transition clinic at a specialist centre. The fi...

The increasing prevalence of congenital heart disease (CHD) can be attributed to major improvements in diagnosis and treatment. Although echocardiography is the most commonly used imaging modality for diagnosis and follow up of subjects with CHD, the evolution of both cardiovascular magnetic resonance (MR) imaging and computed tomography (CT) does...

Diagnosis of ventricular dysfunction in congenital heart disease is more and more based on medical imaging, which allows investigation of abnormal cardiac morphology and correlated abnormal function. Although analysis of 2D images represents the clinical standard, novel tools performing automatic processing of 3D images are becoming available, prov...

Arrow representation of Mode2 throughout the cardiac cycle for Control4 (light blue) and AS3 (orange) in the HLA view. One can notice that during the systolic phase the apex of AS3 moves to the right, while the basal septum of Control4 moves downwards.

Arrow representation of Mode2 throughout the cardiac cycle for Control4 (light blue) and AS3 (orange) in the VLA view.

Arrow representation of Mode2 throughout the cardiac cycle for Control4 (light blue) and AS3 (orange) in the SA view.

Objective: Today's growing medical image databases call for novel processing tools to structure the bulk of data and extract clinically relevant information. Unsupervised hierarchical clustering may reveal clusters within anatomical shape data of patient populations as required for modern precision medicine strategies. Few studies have applied hie...

Patients born with a single functional ventricle typically undergo three-staged surgical palliation in the first years of life, with the last stage realizing a cross-like total cavopulmonary connection (TCPC) of superior and inferior vena cavas (SVC and IVC) with both left and right pulmonary arteries, allowing all deoxygenated blood to flow passiv...

Patients with repaired coarctation of the aorta are thought to have increased afterload due to abnormalities in vessel structure and function. We have developed a novel cardiovascular magnetic resonance protocol that allows assessment of central hemodynamics, including central aortic systolic blood pressure, resistance, total arterial compliance, p...

Atlas-based whole-heart segmentation is a well-established technique for the extraction of key cardiac structures of the adult heart. Despite its relative success in this domain, its implementation in whole-heart segmentation of paediatric patients suffering from a form of congenital heart disease is not straightforward. The aim of this work is to...

Patients with repaired coarctation of the aorta are thought to have increased afterload due to abnormalities in vessel structure and function. We have developed a novel cardiovascular magnetic resonance protocol that allows assessment of central hemodynamics, including central aortic systolic blood pressure, resistance, total arterial compliance, p...

High temporal resolution cine-MRI to assess global functional and morphological parameters in +/Y (WT) and −/Y (KO) mice. Significantly reduced left ventricular end-diastolic volumes in −/Y mice are apparent, shown here in mid-ventricular short axis (KO1, middle panel, compared with WT, left panel). Distinct regional variability in % fractional wal...

Tβ4 -/Y mice depend upon increasing heart rate and ejection fraction to maintain an effectively normal cardiac output. Bolus infusion of the β1-selective antagonist esmolol slowed heart rate and increased LV volumes in both +/Y (WT) and −/Y (KO) hearts. Whereas esmolol treatment markedly reduced SV in WT mice, KO mice were unaffected; cardiac outpu...

Tβ4 knockout mice subjected to dobutamine stress testing, with high temporal cine MR imaging. The inotropic effects of dobutamine increase cardiac output via elevated heart rate and enhanced myocardial contractility. +/Y control mice (WT) decreased ESV with dobutamine treatment, as evidence of a normal contractile reserve. In contrast, −/Y (KO) mic...

Supplementary material

Surgical aortic valve replacement is the most common procedure of choice for the treatment of severe aortic stenosis. Bioprosthetic valves are traditionally sewed-in the aortic root by means of pledget-armed sutures during open-heart surgery. Recently, novel bioprostheses which include a stent-based anchoring system have been introduced to allow ra...

Sarcomere assembly is a highly orchestrated and dynamic process which adapts, during perinatal development, to accommodate growth of the heart. Sarcomeric components, including titin, undergo an isoform transition to adjust ventricular filling. Many sarcomeric genes have been implicated in congenital cardiomyopathies, such that understanding develo...

Computational models of congenital heart disease (CHD) have become increasingly sophisticated over the last 20 years. They can provide an insight into complex flow phenomena, allow for testing devices into patient-specific anatomies (pre-CHD or post-CHD repair) and generate predictive data. This has been applied to different CHD scenarios, includin...

Experimental and computational models can provide insight into complex congenital heart defects, including single ventricle physiology, with the advantage of performing parametric studies [11?14]. Numerical simulations of the hybrid procedure for palliation of hypoplastic left heart syndrome (HLHS) are feasible, and can provide valuable understandi...

OBJECTIVES: Even after successful aortic coarctation repair, there remains a significant incidence of late systemic hypertension and other morbidities. Independently of residual obstruction, aortic arch morphology alone may affect cardiac function and outcome. We sought to uncover the relationship of arch 3-dimensional shape features with functiona...

Objective: To develop a participatory approach in the evaluation of 3D printed patient-specific models of congenital heart disease (CHD) with different stakeholders who would potentially benefit from the technology (patients, parents, clinicians and nurses). Methods: Workshops, focus groups and teaching sessions were organised, targeting differe...

Background: Aortic arch reconstruction after hypoplastic left heart syndrome (HLHS) palliation can vary widely in shape and dimensions between patients. Arch morphology alone may affect cardiac function and outcome. We sought to uncover the relationship of arch three-dimensional shape features with functional and short-term outcome data after tota...

Objectives: Even after successful aortic coarctaion (CoA) repair, there remains a significant incidence of late systemic hypertension and other morbidities. Independent of residual obstruction, aortic arch morphology alone may impact on cardiac function and outcome. We sought to uncover the relationship of arch three-dimensional (3D) shape features...

Background: Nurse education and training are key to providing congenital heart disease (CHD) patients with consistent high standards of care as well as enabling career progression. One approach for improving educational experience is the use of 3D patient-specific models. Objectives: To gather pilot data to assess the feasibility of using 3D mod...

The reservoir-wave hypothesis states that the blood pressure waveform can be usefully divided into a “reservoir pressure” related to the global compliance and resistance of the arterial system, and an “excess pressure” that depends on local conditions. The formulation of the reservoir-wave hypothesis applied to the area waveform is shown, and the a...

Aims: Cardiovascular magnetic resonance (CMR), using adenosine stress perfusion and late-gadolinium enhancement (LGE), is becoming the 'gold standard' non-invasive imaging modality in the assessment of adults with coronary artery disease (CAD). However, despite its proved feasibility in paediatric patients, clinical utility has not been demonstrat...

This chapter presents the experience of the cardiac engineering team within the Centre for Cardiovascular Imaging at Great Ormond Street Hospital for Children (London, UK) in using three-dimensional (3D) printing technology. 3D models can serve different functions towards implementing a patient-specific approach for studying and potentially treatin...

Children born with a single functional right or left ventricle (SV) typically undergo a sequence of staged surgeries aiming to improve the heart’s capability to provide blood flow to body and lungs. In SV patients with hypoplastic left heart syndrome (HLHS), not only the left ventricle but also the aorta is often small and underdeveloped. For those...

Patient-specific numerical models could aid the decision-making process for percutaneous valve selection; in order to be fully informative, they should include patient-specific data of both anatomy and mechanics of the implantation site. This information can be derived from routine clinical imaging during the cardiac cycle, but data on the implanta...

An arts workshop investigated the process of communicating the notion of uniqueness with young people with congenital heart disease (CHD) and whether threedimensional (3D) visualization could be more effective than two-dimensional (2D) visualization for elaborating CHD anatomy and increasing awareness. Young people with CHD (n=7, 14–18 years old) w...

Background: Medical image analysis in clinical practice is commonly carried out on 2D image data, without fully exploiting the detailed 3D anatomical information that is provided by modern non-invasive medical imaging techniques. In this paper, a statistical shape analysis method is presented, which enables the extraction of 3D anatomical shape fe...

Objective Biomarkers play a pivotal role in heart failure (HF) management. Reference values and insights from studies in adults cannot be extrapolated to the paediatric population due to important differences in pathophysiology and compensatory reserve. We assessed the diagnostic utility of four novel biomarkers in paediatric HF. Methods Midregiona...

Despite improving survival rates, patients diagnosed with aortic coarctation (CoA) suffer from late complications post CoA repair and regular screening via cardiac imaging is warranted. Cardiovascular magnetic resonance (CMR) imaging being a cost-effective and accurate tool to provide detailed 3D anatomical shape information, imaging databases are...

Background Post mortem imaging is playing an increasingly important role in perinatal autopsy, and correct interpretation of imaging changes is paramount. This is particularly important following intra-uterine fetal death, where there may be fetal maceration. The aim of this study was to investigate whether any changes seen on a whole body fetal po...

BACKGROUND: Post mortem imaging is playing an increasingly important role in perinatal autopsy, and correct interpretation of imaging changes is paramount. This is particularly important following intra-uterine fetal death, where there may be fetal maceration. The aim of this study was to investigate whether any changes seen on a whole body fetal p...

Aims: This study sought to investigate diagnostic accuracy of echocardiographic measures of great vessels in patients before bidirectional cavopulmonary connection (BCPC) compared with cardiovascular magnetic resonance (CMR). Methods and results: Seventy-two patients (61% after Norwood operation) undergoing BCPC between 2007 and 2012 were assess...

Background Patient-specific simulations can provide insight into the mechanics of cardiovascular procedures. Amongst cardiovascular devices, non-compliant balloons are used in several minimally invasive procedures, such as balloon aortic valvuloplasty. Although these balloons are often included in the computer simulations of these procedures, valid...

Accurate and timely assessment of suspected acute aortic syndrome (AAS) is crucial in this life-threatening condition. Imaging with computed tomography (CT) plays a central role in the diagnosis to allow expedited management. Diagnosis can be made using locally available expertise with optimised scanning parameters making full use of recent advance...

As postmortem magnetic resonance imaging (PMMR) becomes more widely used for investigation following perinatal and paediatric deaths, the best possible images should be acquired. In this article, we review the most widely used published PMMR sequences, together with outlining our acquisition protocol and sequence parameters for fetal, perinatal and...

Fragestellung: Eine fett- und kohlenhydratreiche Diat lost bei Erwachsenen eine inflammatorische Reaktion mit negativen Effekten auf die vaskulare Endothelfunktion aus. Wenig ist hingegen uber die Auswirkungen einer solchen Ernahrung bei Jugendlichen sowie ihre Interaktion mit anderen Risikofaktoren mit Hinblick auf die langfristige kardiovaskulare...

Left ventricular ejection fraction (LVEF) late after arterial switch operation (ASO) is often normal. However, some studies have shown increased indexed end diastolic volume (iEDV) and ventricular mass when compared to healthy controls. We sought to identify LV morphological differences between patients with transposition of the great arteries (TGA...

Ingestion of food is known to increase mesenteric blood flow. It is not clear whether this increased flow demand is compensated by a rise in cardiac output (CO) alone or by redistribution of blood flow from other organs. We used a new comprehensive imaging method to assess the human cardiovascular response to food ingestion. Following a 12-hour fas...

Planning of mitral valve replacement would benefit from preprocedural 3D models that could allow the clinician to fully understand the patient anatomical and functional condition. However, no single image modality can provide the complete picture alone but 3D echocardiography and magnetic resonance imaging (MRI) could be combined to leverage the ad...

Computational fluid dynamics (CFD) can have a complementary predictive role alongside the exquisite visualization capabilities of 4D cardiovascular magnetic resonance (CMR) imaging. In order to exploit these capabilities (e.g., for decision-making), it is necessary to validate computational models against real world data. In this study, we sought t...

Objectives: To compare the diagnostic yield of whole-body post-mortem computed tomography (PMCT) imaging to post-mortem magnetic resonance (PMMR) imaging in a prospective study of fetuses and children. Methods: We compared PMCT and PMMR to conventional autopsy as the gold standard for the detection of (a) major pathological abnormalities related...

Coarctation of the Aorta (CoA) is a cardiac defect that requires surgical intervention aiming to restore an unobstructed aortic arch shape. Many patients suffer from complications post-repair, which are commonly associated with arch shape abnormalities. Determining the degree of shape abnormality could improve risk stratification in recommended scr...

Atlas-based analysis methods rely on the morphological similarity between the atlas and target images, and on the availability of labelled images. Problems can arise when the deformations introduced by pathologies affect the similarity between the atlas and a patient's image. The aim of this work is to exploit the morphological dissimilarities betw...

Aims: We report the application of patient-specific computational models to plan the treatment of complex aortic re-coarctation (rCoA) with a proximal aberrant right subclavian artery in a patient who had previously undergone bare metal stenting. Methods and results: Clinically acquired images were used to set up patient-specific computational mode...

Planning of mitral valve replacement would benefit from pre-procedural 3D models that could allow the clinician to fully understand the patient anatomical and functional condition. However, no single image modality can provide the complete picture alone but 3D echocar-diography and magnetic resonance imaging (MRI) could be combined to leverage the...

Isometric exercise may unmask cardiovascular disease not evident at rest, and cardiovascular magnetic resonance (CMR) imaging is proven for comprehensive resting assessment. This study devised a simple isometric exercise CMR methodology and assessed the hemodynamic response evoked by isometric exercise. A biceps isometric exercise technique was dev...

Post-mortem (PM) magnetic resonance imaging (MRI) is increasingly used as an alternative to conventional autopsy in babies dying from neonatal encephalopathy. However, the confounding effect of post-mortem changes on the detection of ante-mortem ischemic injury is unclear. We examined whether quantitative MR measurements can accurately distinguish...