The anatomy of the aortic root

Development of idealized human aortic models for in vitro and in silico hemodynamic studies

Background

The aorta, a central component of the cardiovascular system, plays a pivotal role in ensuring blood circulation. Despite its importance, there is a notable lack of idealized models for experimental and computational studies.

Objective

This study aims to develop computer-aided design (CAD) models for the idealized human aorta, intended for studying hemodynamics or solid mechanics in both in vitro and in silico settings.

Methods

Various parameters were extracted from comprehensive literature sources to evaluate major anatomical characteristics of the aorta in healthy adults, including variations in aortic arch branches and corresponding dimensions. The idealized models were generated based on averages weighted by the cohort size of each study for several morphological parameters collected and compiled from image-based or cadaveric studies, as well as data from four recruited subjects. The models were used for hemodynamics assessment using particle image velocimetry (PIV) measurements and computational fluid dynamics (CFD) simulations.

Results

Two CAD models for the idealized human aorta were developed, focusing on the healthy population. The CFD simulations, which align closely with the PIV measurements, capture the main global flow features and wall shear stress patterns observed in patient-specific cases, demonstrating the capabilities of the designed models.

Conclusions

The collected statistical data on the aorta and the two idealized aorta models, covering prevalent arch variants known as Normal and Bovine types, are shown to be useful for examining the hemodynamics of the aorta. They also hold promise for applications in designing medical devices where anatomical statistics are needed.

Morphometry and topography of the coronary ostia in the dog

Introduction

The purpose of this study was to perform a morphometric examination of the coronary ostia, including their location in the area of the aortic sinuses, and to describe variations in ostia structure in the domestic dog.

Material and Methods

The study was conducted on the hearts of 91 pedigree dogs of both sexes, aged 1 to 18 years (median 9 years), with a body weight from 1.2 to 65 kg (median 20.7 kg). Morphometric examinations of the coronary ostia were performed in the studied individuals, and the location of the structures in relation to the intercommissural lines was determined.

Results

Three types of location of the coronary ostia were distinguished, i.e. below the intercommissural line (type I), on the intercommissural line (type II), and above the intercommissural line (type III). In the studied dogs, the most common location of the ostia was type I - found in the left coronary artery of 74/91 dogs (81%) and in the right coronary artery of 42/91 dogs (46%). Morphological variations were shown in 36/91 dogs (40%) in the structure of the coronary ostia, including the presence of accessory ostia. The most common variation was the presence of an accessory ostium near the ostium of the right coronary artery, which was found in 28/91 dogs (31%).

Conclusion

The results may be useful in developing standards for procedures to replace the whole or part of the aortic valve and repair the coronary artery.

Three-dimensional transoesophageal echocardiography: how to use and when to use-a clinical consensus statement from the European Association of Cardiovascular Imaging of the European Society of Cardiology

Three-dimensional transoesophageal echocardiography (3D TOE) has been rapidly developed in the last 15 years. Currently, 3D TOE is particularly useful as an additional imaging modality for the cardiac echocardiographers in the echo-lab, for cardiac interventionalists as a tool to guide complex catheter-based procedures cardiac, for surgeons to plan surgical strategies, and for cardiac anaesthesiologists and/or cardiologists, to assess intra-operative results. The authors of this document believe that acquiring 3D data set should become a 'standard part' of the TOE examination. This document provides (i) a basic understanding of the physic of 3D TOE technology which enables the echocardiographer to obtain new skills necessary to acquire, manipulate, and interpret 3D data sets, (ii) a description of valvular pathologies, and (iii) a description of non-valvular pathologies in which 3D TOE has shown to be a diagnostic tool particularly valuable. This document has a new format: instead of figures randomly positioned through the text, it has been organized in tables which include figures. We believe that this arrangement makes easier the lecture by clinical cardiologists and practising echocardiographers.

Preventing Complications During Mapping and Ablation of Left Ventricular Summit Arrhythmias

The left ventricular summit is a site of origin for idiopathic ventricular arrhythmias. With advancements in mapping and ablation techniques, sites previously considered inaccessible can now be approached. Anatomical knowledge of the 3-dimensional landmarks of this space is important, as critical structures reside within its boundaries and are potentially liable to collateral injury during ablation. This article reviews reported complications from ablation of ventricular arrhythmias arising from the left ventricular summit and its vicinity and discusses the pros and cons of different ablation technique and the role of an individualized anatomical approach to reduce procedural related complications and improve outcomes.

Valve Repair in Aortic Insufficiency: A State-of-the-art Review

Aortic valve insufficiency (AI) describes the pathology of blood leaking through the aortic valve to the left ventricle during diastole and is classified as mild, moderate or severe according to the volume of regurgitating blood. Intervention is required in severe AI when the patient is symptomatic or when the left ventricular function is impaired. Aortic valve replacement has been considered the gold standard for decades for these patients, but several repair techniques have recently emerged that offer exceptional stability and long-term outcomes. The appropriate method of repair is selected based on the mechanism of AI and each patient's anatomic variations. This review aims to describe different pathologies of AI based on its anatomy, along with the different surgical techniques of aortic repair and their reported results.

The Medical versus Zoological Concept of Outflow Tract Valves of the Vertebrate Heart

The anatomical elements that in humans prevent blood backflow from the aorta and pulmonary artery to the left and right ventriclesare the aortic and pulmonary valves, respectively. Each valve regularly consists of three leaflets (cusps), each supported by its valvular sinus. From the medical viewpoint, each set of three leaflets and sinuses is regarded as a morpho-functional unit. This notion also applies to birds and non-human mammals. However, the structures that prevent the return of blood to the heart in other vertebrates are notably different. This has led to discrepancies between physicians and zoologists in defining what a cardiac outflow tract valve is. The aim here is to compare the gross anatomy of the outflow tract valvular system among several groups of vertebrates in order to understand the conceptual and nomenclature controversies in the field.

Morphological importance of coronary ostia in sheep and swine

The aortic valve was investigated in 58 sheep and 60 swine without heart disease. After fixation in 4% formalin, the distance between the ostia and the elements of the right/left aortic sinuses was measured. For the left coronary ostium (LCO), it was found that in sheep 81% were below and 19% at the level of intercomissural line (IL). In pigs, 88.3% were below and 11.7% at the IL level. In sheep, the OCL was close to the right valve commissure (CVR) in 98.3% and close to the left valve commissure (CVV) in 1.7%. In pigs, it was close to RVC at 83.3% and close to LVC at 16.7%. Regarding to RCO, it was found that in sheep 69% was below, 1.7% was above and 29.3% at the IL level. In pigs, 20% were below, 15% above and 65% at the IL level. The distance of the RCO in relation to the valve commissures was 56.9% close to LVC and 43.1% close to RVC in sheep. In pigs, 81.7% were close to LVC and 18.3% close to RVC. The position of LCO was balanced between sheep and swine, while the RCO in swine was closer to CVE when compared with sheep. The accessory coronary ostium was observed in 18.6% of sheep and 10% of pigs. Thus, it is concluded that in sheep and swine the left coronary artery is perfused only in ventricular diastole. Perfusion of the right coronary artery occurs more frequently in diastole and less frequently in ventricular systole.

Design of an aortic polymeric valve with asymmetric leaflets and evaluation of its performance by finite element method

BACKGROUND

The geometry of leaflets plays a significant role in prosthetic valves' (PVs) performance. Typically, natural aortic valves have three unequal leaflets, which differ in size. The present study aims to design an asymmetric tri-leaflet polymeric valve with one large and two small leaflets based on commissure lengths and leaflet eccentricities.

METHODS

Eccentricity was related to commissure lengths based on the deformation of the free margins for the fully-opened state of leaflets. The polystyrene-block-polyethylene-polypropylene-block-polystyrene polymer characterized the material properties of the leaflets. The Finite Element Method (FEM) was used to evaluate performance parameters, including maximum geometric orifice area (GOA), average GOA, maximum von Mises stress, and leaflet's coaptation surface area (CSA).

RESULTS

Asymmetric valves with no eccentricity provided a low level of GOA because the asymmetric form of small leaflets caused them to close faster than the large leaflet, leading to a sudden drop in the GOA during systole. As the radial curve tends towards a straight line, an undesirable coaptation occurs, and peak stress increases despite higher GOAs. A new radial curve consisting of two straight lines connected by an arc that provided 25.64 mm² coaptation surface area (CAS) and 117.54 mm² average GOA, was proposed to improve coaptation and GOA.

CONCLUSION

The radial curve of leaflets affects the valve's performance more than other geometric parameters. The combination of straight lines and arcs for radial curves was selected as the reference model for asymmetric valves with one large and two small leaflets.

Giant Right Coronary Ostial Aneurysm in a Patient With Marfan Syndrome

Aortic root dilation and aortic insufficiency are prominent causes of morbidity in Marfan syndrome. These pathologies necessitate surgical repair, including aortic root and aortic valve replacement procedures, to improve prognosis. Coronary artery aneurysms, particularly giant coronary ostial aneurysms, are rare complications of these surgeries in the Marfan population. Due to the significant life-threatening sequelae of coronary artery aneurysms, it is imperative to bring attention regarding this complication to the radiologist assessing thoracic imaging in this patient population.

Application of prosthesis eversion method for ascending aorta replacement guarantees better clinical outcomes of type A acute aortic dissection surgery

Background

The advantages of prosthesis eversion method in patients diagnosed with Stanford type A acute aortic dissection (AAD) undergoing ascending aorta replacement (AAR) is unknown. This research is designed to explore it.

Methods

We retrospectively analyzed the data of a total of 283 patients diagnosed with type A aortic dissection that underwent surgery in Renmin Hospital of Wuhan University from March, 2006 to April, 2020. Eighty-eight patients underwent surgical repair with traditional continuous suture technique, and 195 patients received prosthesis eversion. Baseline data, intra-operative data and early-stage clinical results were collected and statistically analyzed.

Results

Baseline data were similar except for age, incidence of hyperlipidemia and taking ACEI/ARB drugs (P<0.05). Cardiopulmonary bypass time, cross-clamp time, circulation arrest time, hemostasis time and total operation time in the traditional method group were far longer than in the prothesis eversion group (P<0.01). The operative mortality was similar (P>0.01). Post-operatively, there was no statistically significant difference in the mean ventilation time, mortality, incidence of re-exploration, tracheostomy, paraplegia, long-term coma and stroke between the two groups (P>0.05). Patients in the traditional method group had a longer duration stay in ICU and hospital than patients in the prosthesis eversion group (P<0.05). Patients in the traditional method group received more red blood cells (RBC) (P<0.01), plasma (P<0.05), fibrinogen (P<0.01) and albumin (P<0.05) transfusions, and CoSeal™ surgical sealant (P<0.05) than patients in the prosthesis eversion group.

Conclusions

Our experience and statistical analysis showed prosthesis eversion method to have some advantage in reducing blood loss and improving clinical results compared with repair with continuous suture. This technique is both simple to learn and perform.

State-of-the art bicuspid aortic valve repair in 2020

Patients with a bicuspid aortic valve (BAV) frequently require surgical intervention for aortic regurgitation (AR) and/or aneurysm. Valve-preserving surgery and repair of regurgitant BAVs have evolved into an increasingly used alternative to replacement. Anatomic predictors of possible repair failures have been identified and solutions developed. Using current techniques most non-calcified BAVs can be preserved or repaired. Excellent repair durability and freedom from valve-related complications can be achieved if all pathologic components of aortic valve and root including annular dilatation are corrected. Anatomic variations must be addressed using tailored approaches.

Focus on the annuloplasty in aortic valve repair: implications from a quantitative multislice computed tomography analysis

Background

Aortic valve (AV) repair has evolved towards a treatment alternative in young patients with AV regurgitation and was accompanied by the development of surgical repair strategies. An efficient and reproducible AV annulus stabilization (i.e., annuloplasty) has been proposed as a crucial component to obtain the long-term stability of AV repair. However, there is still major controversy regarding the most appropriate annuloplasty approach. We aimed to address AV annulus structures which are relevant for AV annuloplasty, based on MS-CT data.

Methods

We retrospectively analysed 326 consecutive patients with AV disease who all underwent preprocedural MS-CT examination. Study cohort was subdivided according to the underlying AV pathology: 25 patients with aortic regurgitation (AR subgroup) (mean age 73±11 years, 68% male), 243 patients with aortic stenosis (AS subgroup) (73±11 years, 68% male) and 58 patients with normally functioning AV (normal AV subgroup) (mean age 76±7 years, 36% male). We systematically measured maximum and minimum AV annulus diameter, AV annular area, projected AV annular perimeter and anatomic AV annular perimeter during mid-systole using MS-CT data. Based on these measurements, AV annular eccentricity index was calculated [(max AV annulus × 100/min AV annulus) - 100]. Furthermore, we assessed the tissue components of AV annular plane, distinguishing between muscular and fibrous portions of the basal ring.

Results

AV annular eccentricity index was significantly larger in the normal AV-subgroup as compared to the AR-subgroup (33.2%±10.7% vs. 27.8%±9.2%; P=0.048) as well as to the AS-subgroup (33.2%±10.7% vs. 20.4%±8.8%; P<0.001). AV annular area was significantly larger in the AR subgroup as compared to the AS subgroup (5.7±1.0 vs. 5.1±0.8 cm²; P=0.003) and normal AV subgroup (5.7±1.0 vs. 4.8±0.8 cm²; P<0.001). Intramuscular plane in the right coronary sinus was significantly increased in the AR subgroup vs. AS subgroup (12.8±2.7 vs. 7.5±3.6 mm; P<0.001) and normal AV subgroup (12.8±2.7 vs. 8.7±3.0 mm; P<0.001). Muscular component of the basal ring was significantly reduced in the AR subgroup vs. AS subgroup (37.5%±5.1% vs. 40.5%±5.5%; P=0.039) and normal AV subgroup (37.5%±5.1% vs. 44.3%±10.2%; P=0.001).

Conclusions

MS-CT enables a quantitative analysis of aortic root anatomy which may have an impact on AV annuloplasty. AR patients differ significantly regarding their AV annular dimensions and basal ring morphology as compared to the AS patients and those with a normal AV function. These findings may have major implications in tricuspid AV repair when designing the most appropriate AV annulus stabilisation technique.

Expert consensus document on the assessment of the severity of aortic valve stenosis by echocardiography to provide diagnostic conclusiveness by standardized verifiable documentation

According to recent recommendations on echocardiographic assessment of aortic valve stenosis direct measurement of transvalvular peak jet velocity, calculation of transvalvular mean gradient from the velocities using the Bernoulli equation and calculation of the effective aortic valve area by continuity equation are the appropriate primary key instruments for grading severity of aortic valve stenosis. It is obvious that no gold standard can be declared for grading the severity of aortic stenosis. Thus, conclusions of the exclusive evaluation of aortic stenosis by Doppler echocardiography seem to be questionable due to the susceptibility to errors caused by methodological limitations, mathematical simplifications and inappropriate documentation. The present paper will address practical issues of echocardiographic documentation to satisfy the needs to analyze different scenarios of aortic stenosis due to various flow conditions and pressure gradients. Transesophageal and multidimensional echocardiography should be implemented for reliable measurement of geometric aortic valve area and of cardiac dimensions at an early stage of the diagnostic procedure to avoid misinterpretation due to inconsistent results.

Aortic Valve Repair: From Concept to Future Targets

Aortic valve repair has become an important treatment alternative to patients with aortic insufficiency. In this paper, we review refinements and advances in the understanding of core concepts of aortic valve anatomy and pathophysiology which have enhanced our approach to aortic valve preservation and repair. With these improvements in understanding and techniques, the outcome for aortic valve repair continues to improve. We also review current challenges in the field and explore potential areas of innovation and future study including timing of surgical intervention for aortic insufficiency, comparisons between aortic valve repair and replacement in randomized trials, and development of personalized surgical management plan based on patient-specific pathologies. These advances will further establish the role of aortic valve repair in the management of aortic valve and aortic disease.

Notch-Tnf signalling is required for development and homeostasis of arterial valves

Aims

Congenital anomalies of arterial valves are common birth defects, leading to valvar stenosis. With no pharmaceutical treatment that can prevent the disease progression, prosthetic replacement is the only choice of treatment, incurring considerable morbidity and mortality. Animal models presenting localized anomalies and stenosis of congenital arterial valves similar to that of humans are critically needed research tools to uncover developmental molecular mechanisms underlying this devastating human condition.

Methods and results

We generated and characterized mouse models with conditionally altered Notch signalling in endothelial or interstitial cells of developing valves. Mice with inactivation of Notch1 signalling in valvar endothelial cells (VEC) developed congenital anomalies of arterial valves including bicuspid aortic valves and valvar stenosis. Notch1 signalling in VEC was required for repressing proliferation and activating apoptosis of valvar interstitial cells (VIC) after endocardial-to-mesenchymal transformation (EMT). We showed that Notch signalling regulated Tnfα expression in vivo, and Tnf signalling was necessary for apoptosis of VIC and post-EMT development of arterial valves. Furthermore, activation or inhibition of Notch signalling in cultured pig aortic VEC-promoted or suppressed apoptosis of VIC, respectively.

Conclusion

We have now met the need of critical animal models and shown that Notch-Tnf signalling balances proliferation and apoptosis for post-EMT development of arterial valves. Our results suggest that mutations in its components may lead to congenital anomaly of aortic valves and valvar stenosis in humans.

Development and maturation of the fibrous components of the arterial roots in the mouse heart

The arterial roots are important transitional regions of the heart, connecting the intrapericardial components of the aortic and pulmonary trunks with their ventricular outlets. They house the arterial (semilunar) valves and, in the case of the aorta, are the points of coronary arterial attachment. Moreover, because of the semilunar attachments of the valve leaflets, the arterial roots span the anatomic ventriculo-arterial junction. By virtue of this arrangement, the interleaflet triangles, despite being fibrous, are found on the ventricular aspect of the root and located within the left ventricular cavity. Malformations and diseases of the aortic root are common and serious. Despite the mouse being the animal model of choice for studying cardiac development, few studies have examined the structure of their arterial roots. As a consequence, our understanding of their formation and maturation is incomplete. We set out to clarify the anatomical and histological features of the mouse arterial roots, particularly focusing on their walls and the points of attachment of the valve leaflets. We then sought to determine the embryonic lineage relationships between these tissues, as a forerunner to understanding how they form and mature over time. Using histological stains and immunohistochemistry, we show that the walls of the mouse arterial roots show a gradual transition, with smooth muscle cells (SMC) forming the bulk of wall at the most distal points of attachments of the valve leaflets, while being entirely fibrous at their base. Although the interleaflet triangles lie within the ventricular chambers, we show that they are histologically indistinguishable from the arterial sinus walls until the end of gestation. Differences become apparent after birth, and are only completed by postnatal day 21. Using Cre-lox-based lineage tracing technology to label progenitor populations, we show that the SMC and fibrous tissue within the walls of the mature arterial roots share a common origin from the second heart field (SHF) and exclude trans-differentiation of myocardium as a source for the interleaflet triangle fibrous tissues. Moreover, we show that the attachment points of the leaflets to the walls, like the leaflets themselves, are derived from the outflow cushions, having contributions from both SHF-derived endothelial cells and neural crest cells. Our data thus show that the arterial roots in the mouse heart are similar to the features described in the human heart. They provide a framework for understanding complex lesions and diseases affecting the aortic root.

Morphometry of the coronary ostia and the structure of coronary arteries in the shorthair domestic cat

The aim of this study was to measure the area of the coronary ostia, assess their localization in the coronary sinuses and to determine the morphology of the stem of the left and right coronary arteries in the domestic shorthair cat. The study was conducted on 100 hearts of domestic shorthair cats of both sexes, aged 2-18 years, with an average body weight of 4.05 kg. A morphometric analysis of the coronary ostia was carried out on 52 hearts. The remaining 48 hearts were injected with a casting material in order to carry out a morphological assessment of the left and right coronary arteries. In all the studied animals, the surface of the left coronary artery ostium was larger than the surface of the right coronary artery ostium. There were four types of the left main coronary artery: type I (23 animals, 49%)-double-branched left main stem (giving off the left circumflex branch and the interventricular paraconal branch, which in turn gave off the septal branch), type II (12 animals, 26%)-double-branched left main stem (giving off the left circumflex branch and the interventricular paraconal branch without the septal branch), type III (11 animals, 23%)-triple-branched left main stem (giving off the left circumflex branch, interventricular branch and the septal branch, type IV (1 animal, 2%)-double-branched left main stem (giving off the interventricular paraconal branch and the left circumflex branch, which in turn gave off the septal branch). The left coronary artery ostium is greater than the right one. There is considerable diversity in the branches of proximal segment of the left coronary artery, while the right coronary artery is more conservative. These results can be useful in defining the optimal strategies in the endovascular procedures involving the coronary arteries or the aortic valve in the domestic shorthair cat.

Heart Valve Biomechanics and Underlying Mechanobiology

Heart valves control unidirectional blood flow within the heart during the cardiac cycle. They have a remarkable ability to withstand the demanding mechanical environment of the heart, achieving lifetime durability by processes involving the ongoing remodeling of the extracellular matrix. The focus of this review is on heart valve functional physiology, with insights into the link between disease-induced alterations in valve geometry, tissue stress, and the subsequent cell mechanobiological responses and tissue remodeling. We begin with an overview of the fundamentals of heart valve physiology and the characteristics and functions of valve interstitial cells (VICs). We then provide an overview of current experimental and computational approaches that connect VIC mechanobiological response to organ- and tissue-level deformations and improve our understanding of the underlying functional physiology of heart valves. We conclude with a summary of future trends and offer an outlook for the future of heart valve mechanobiology, specifically, multiscale modeling approaches, and the potential directions and possible challenges of research development. © 2016 American Physiological Society. Compr Physiol 6:1743-1780, 2016.

Anatomical Basis for the Cardiac Interventional Electrophysiologist

The establishment of radiofrequency catheter ablation techniques as the mainstay in the treatment of tachycardia has renewed new interest in cardiac anatomy. The interventional arrhythmologist has drawn attention not only to the gross anatomic details of the heart but also to architectural and histological characteristics of various cardiac regions that are relevant to the development or recurrence of tachyarrhythmias and procedural related complications of catheter ablation. In this review, therefore, we discuss some anatomic landmarks commonly used in catheter ablations including the terminal crest, sinus node region, Koch's triangle, cavotricuspid isthmus, Eustachian ridge and valve, pulmonary venous orifices, venoatrial junctions, and ventricular outflow tracts. We also discuss the anatomical features of important structures in the vicinity of the atria and pulmonary veins, such as the esophagus and phrenic nerves. This paper provides basic anatomic information to improve understanding of the mapping and ablative procedures for cardiac interventional electrophysiologists.

The clinical anatomy of high take-off coronary arteries

A number of criteria are used in the literature to describe high take-off coronary arteries, which can in part, explain the divide in the literature on the pathological significance of this anomaly. This study presents the anatomical variations of high take-off coronary arteries to draw attention to the possible clinical implications they may cause during angiography and other surgical procedures. The English Literature was searched to review high take-off coronary arteries. A high take-off coronary artery arising at least 1 cm in adults or 20% the depth of the sinus in children above the sinutubular junction, is considered of greater clinical relevance and was included in our meta-analysis. High take-off coronaries by other criteria was also included as part of the comprehensive review. Exclusion criteria were reports made in case studies or case reviews. The prevalence of high take-off coronary arteries in our study was 26 of 12,899 (0.202%). High take-off coronary arteries were found to originate up to 5 cm above the sinutubular junction. Right coronary arteries made up 84.46% of high take-off coronary arteries reported in the literature. Three (0.023%) cases that originated more than one centimeter above the sinutubular junction was associated with sudden cardiac death. This is a higher reported association than in studies that used other criteria for classification. It is important for clinicians to recognize the importance of correctly diagnosing high take-off coronary arteries in patients with coexisting cardiac morbidities so that suitable management plans can be developed.

Effects of Age-Related Aortic Root Anatomic Changes on Left Ventricular Outflow Tract Pace-Mapping Morphologies: A Cardiac Magnetic Resonance Imaging Validation Study

INTRODUCTION

Outflow tract ventricular arrhythmias (OT VAs) are common and catheter ablation is an effective treatment option. We sought to investigate the relationship between age-related anatomic aortic root changes and QRS morphology during left ventricular outflow tract (LVOT) pace-mapping using cardiac magnetic resonance (CMR) imaging.

METHODS AND RESULTS

Fifty-one patients undergoing CMR imaging were divided into 3 groups based on age (<40, 40-60, >60 years). We measured the angle of the aortic root, the aorta to ventricular septal angle, the distance between the right coronary cusp (RCC) and left coronary cusp (LCC), and the distance between the ascending and descending aorta. Additionally, we evaluated the QRS morphologies obtained during pace-mapping from the LVOT. In older patients, LCC was more superior to the RCC (P < 0.01). Age was positively correlated with the aortic root angle (r² = 0.481, P < 0.01) as well as the distances between the ascending and descending aorta at a level below the arch (r² = 0.569, P < 0.01). In older patients, LVOT pace-mapping (performed in 16 patients) demonstrated higher maximal R-wave amplitude, and was greater when pacing from the LCC versus the RCC in lead III (1.8 ± 0.7 vs. 1.0 ± 0.5 mV, P = 0.02).

CONCLUSION

The anatomy of the aortic root changes with age, and age-related aortic root changes may affect the QRS morphology during pace-mapping. Understanding the potential anatomic changes that accompany aging is important to maximize the efficacy of catheter ablation of OT VAs.