Outflow Tract Diameter Research Articles

Comparison of Aortic Root Diameter to Left Ventricular Outflow Diameter Versus Body Surface Area in Patients With Marfan Syndrome

Aortic root dilation is important in the diagnosis of familial aortic syndromes, such as Marfan syndrome, and an important risk factor for aortic complications, such as dissection or rupture. Transthoracic echocardiography reliably measures the absolute aortic root size; however, the degree of abnormality of the measurement requires correction for the expected normal aortic root size for each patient. The expected normal size is currently predicted according to the body surface area (BSA) and age. However, the correlation between root size and BSA is imperfect, particularly for older patients. A potential exists to improve the diagnosis and treatment of patients with aortic disease, with an improved estimation of normal aortic root size. A reference size derived from within the cardiovascular system has been hypothesized to provide a more direct correlation with the aortic root size. Images from the Stanford echocardiography database were reviewed, and measurements of the aortic root and internal dimensions were performed in a control cohort (n = 150). The measurements were repeated in adult patients with Marfan syndrome (n = 70) on serial echocardiograms (145 total studies reviewed). Of the 150 control patients, excellent correlation was found between the aortic root and left ventricular outflow tract diameters, r(2) = 0.67, and r(2) = 0.34 with BSA (p <0.0001, for both). More importantly, using the left ventricular outflow tract to predict the normal aortic root size, instead of the BSA and age, improved the diagnostic accuracy of aortic root measurements for diagnosing Marfan syndrome. In conclusion, an internal cardiovascular reference, the left ventricular outflow tract diameter, can improve the diagnosis of aortic disease and might provide a better reference for the degree of abnormality.

Measuring cardiac index with a focused cardiac ultrasound examination in the ED

ObjectivesNoninvasive technology may assist the emergency department (ED) physician in determining the hemodynamic status in critically ill patients. The objective of our study was to show that ED physicians can accurately measure cardiac index (CI) by performing a bedside focused cardiac ultrasound examination. MethodsA convenience sample of adult subjects were prospectively enrolled. Cardiac index, left ventricular outflow tract (LVOT) diameter, velocity time integral (VTI), stroke volume index, and heart rate were obtained by trained ED physicians and a certified cardiac sonographer. The primary outcome was percent of optimal LVOT diameter and VTI measurements as verified by an expert cardiologist. ResultsOne hundred patients were enrolled, with obtainable CI measurements in 97 patients. Cardiac index, LVOT diameter, VTI, stroke volume index, and heart rate measurements by ED physician were 2.42 ± 0.70 L min−1 m−2, 2.07 ± 0.22 cm, 18.30 ± 3.71 cm, 32.34 ± 7.92 mL beat−1 m−2, and 75.32 ± 13.45 beats/min, respectively. Measurements of LVOT diameter by ED physicians and sonographer were optimal in 90.0% (95% confidence interval, 82.6%-94.5) and 91.3% (73.2%-97.6%) of patients, respectively. Optimal VTI measurements were obtained in 78.4% (69.2%-85.4%) and 78.3% (58.1%-90.3%) of patients, respectively. In 23 patients, the correlation (r) for CI between ED physician and sonographer was 0.82 (0.60-0.92), with bias and limits of agreement of −0.11 (−1.06 to 0.83) L min−1 m−2 and percent difference of 12.4% ± 10.1%. ConclusionsEmergency department ED physicians can accurately measure CI using standard bedside ultrasound. A focused ultrasound cardiac examination to derive CI has potential use in the management of critical ill patients in the ED.

Right ventricular morphology on catheter angiography: Variations and its implications for the diagnosis of arrhythmogenic right ventricular cardiomyopathy

Catheter angiography is one modality used to diagnose right ventricular (RV) structural abnormalities in suspected arrythmogenic right ventricular dysplasia or cardiomyopathy (ARVC) patients. The appearance of the normal RV on angiography is poorly defined. This study aimed to assess RV morphology in a control group to define the range of normal appearances. RV angiography was performed in 46 subjects (mean age 59 years; 70% male) undergoing coronary angiography for suspected coronary artery disease. Qualitative assessment for RV dilatation, regional wall motion abnormalities (RWMAs), pattern of trabeculae, and presence of micro-aneurysms was performed. Right ventricular outflow tract (RVOT) diameter was measured. Regional or global RV dilatation was considered to be present in 17 patients, RWMA in 13, an abnormal trabecular pattern in 10, and microaneurysms noted in two. The RVOT diameter ranged from 1.78 to 3.51 cm in right anterior oblique view and 2.33 to 4.38 cm in left anterior oblique view. The apparent prevalence of abnormal RV morphology in individuals who have no known RV pathology implies that detection of such is not necessarily of diagnostic significance in suspected ARVC. Significant inter-observer variation limits the usefulness of qualitative assessment; quantitative assessment is preferred therefore.

Impact of Aortic Regurgitation After Transcatheter Aortic Valve Implantation: Results From the REVIVAL Trial

Understanding the severity of aortic regurgitation (AR) after transcatheter aortic valve implantation, its impact on left ventricular (LV) structure and function, and the structural factors associated with worsening AR could lead to improvements in patient selection, implantation technique, and valve design. Initial studies in patients at high risk of surgical aortic valve replacement have reported both central valvular and paravalvular AR after transcatheter aortic valve implantation. Transthoracic echocardiograms were quantified from 95 patients in the REVIVAL (TRanscatheter EndoVascular Implantation of VALves) trial. Transthoracic echocardiograms were obtained before implantation of the Edwards-Sapien valve (Edwards Lifesciences, Irvine, California) and thereafter at selected intervals. Measurements included LV internal diameters and volumes, ejection fraction, aortic valve area, and the degree of aortic regurgitation. Measures of degree of native leaflet mobility, thickness, and calcification, as well as left ventricular outflow tract, aortic annulus, and aortic root diameters were also made. Eighty-four patients remained after 11 were excluded; 26 (29.8%) died over a period of 3 years. At 24 h post-implantation, 75% had some degree of AR, mostly paravalvular. By 1 year, the mean AR grade increased slightly, but not significantly (1.1 ± 0.8 to 1.3 ± 0.9), and all measures of LV structure and function improved (LV ejection fraction, 50.7 ± 16.1% to 59.4 ± 14.0%). Native aortic leaflet calcification and annulus diameter correlated significantly with the severity of AR at 1 year (p < 0.05). AR after transcatheter aortic valve implantation is frequent but is rarely more than mild. Although AR progresses, it is not associated with a harmful impact on LV structure and function over the first year. Native valve calcification and aortic annulus diameter influence the degree of AR at 6 months.

Hemodynamics in the Cardiac Catheterization Laboratory of the 21st Century

There has been a striking evolution in the role of the cardiac catheterization laboratory over the past decades.1 In the 1950s and 1960s, hemodynamic assessment in the cardiac catheterization laboratory was essential for understanding the physiology and pathophysiology of patients with cardiovascular diseases. With the development of surgical interventions to treat patients with valvular and congenital heart disease, it became necessary for the cardiac catheterization laboratory to provide an accurate hemodynamic assessment, laying out a therapeutic road map. Nearly all patients who had open heart surgery underwent a complete hemodynamic catheterization before surgery. In the 1980s and 1990s, the evolution of 2-dimensional echocardiography and Doppler echocardiography provided an alternative noninvasive approach for the assessment of both cardiac anatomy and hemodynamics in patients with structural heart disease.2 By measuring blood flow velocities noninvasively, Doppler echocardiography was able to provide information on volumetric flow, intracardiac pressures, pressure gradients, and valve areas, as well as diastolic filling of the heart. Furthermore, noninvasive studies could be repeated easily, allowing the practitioner to follow the progress of his/her patient's condition longitudinally. At the same time, there was growing emphasis on coronary angiography for defining epicardial coronary disease with the subsequent development of interventional approaches for coronary disease with catheter-based therapies. As the major focus in the catheterization laboratory shifted to the diagnosis and treatment of the patient with acute and chronic coronary artery disease, the hemodynamic assessment of patients with structural heart disease was left to the noninvasive echocardiographic laboratory. As a consequence, many cardiac catheterization laboratories provided neither the training nor the expertise to assess hemodynamics properly. However, the advent of procedures such as balloon valvotomy, percutaneous valve implantation, and septal ablation has revived interest in structural heart disease and provided the invasive cardiologist with an armamentarium to treat patients who previously …

Left Ventricular Longitudinal Function Predicts Life-Threatening Ventricular Arrhythmia and Death in Adults With Repaired Tetralogy of Fallot

Sudden cardiac death and life-threatening ventricular arrhythmia remain a concern in adult patients with repaired tetralogy of Fallot. Longitudinal left ventricular (LV) function is sensitive in detecting early myocardial damage and may have prognostic implications in this setting. We included 413 tetralogy of Fallot patients (age, 36 ± 13 years; QRS duration, 148 ± 27 milliseconds; LV ejection fraction, 55 ± 10%). A composite end point of sudden cardiac death/life-threatening ventricular arrhythmia (sustained ventricular tachycardia, resuscitated sudden cardiac death, or appropriate implantable cardioverter-defibrillator discharge) was used. During a median follow-up of 2.9 years, 5 patients died suddenly, 9 had documented sustained ventricular tachycardia, and another 5 had appropriate implantable cardioverter-defibrillator shocks. On univariate Cox analysis, QRS duration (hazard ratio [HR], 1.02 per 1 ms; P=0.046), right atrial area (HR, 1.05 per 1 cm(2); P=0.02), right ventricular fractional area change (HR, 0.94 per 1%; P=0.02), right ventricular outflow tract diameter (HR, 1.08 per 1 mm; P=0.01), mitral annular plane systolic excursion (HR, 0.84 per 1 mm; P=0.03), and LV global longitudinal 2-dimensional strain (HR, 0.87 per 1%; P=0.03) were related to the combined end point. On bivariable analysis, mitral annular plane systolic excursion and LV global longitudinal 2-dimensional strain were related to outcome independently of QRS duration (P=0.002 and P=0.01, respectively). In addition, a combination of echocardiographic variables, including right atrial area, right ventricular fractional area change, and LV global longitudinal 2-dimensional strain or mitral annular plane systolic excursion, was also found to be significantly related to outcome (P<0.001; c statistic, 0.70). LV longitudinal dysfunction was associated with greater risk of sudden cardiac death/life-threatening ventricular arrhythmias. In combination with echocardiographic right heart variables, also available from routine echocardiography, these measures provide important outcome information and should be considered a useful adjunct to established markers such as QRS duration in the estimation of prognosis in this challenging population.

Two‐Dimensional Color Doppler Echocardiography for Left Ventricular Stroke Volume Assessment: A Comparison Study with Three‐Dimensional Echocardiography

Whether measurement of left ventricular outflow tract diameter (LVOTd) using color Doppler (CD) in order to more accurately define LVOTd is more accurate for determination of stroke volume (SV) than gray scale and compare it with direct measurement of LVOT area (a) using three-dimensional echocardiography (3DE) for SV determination. Twenty-one volunteers were examined. LVOTa was calculated by two-dimensional echocardiography (2DE) using the following formula: π× (d/2)(2) , d = LVOT diameter by gray scale and CD, respectively. Planimetry of LVOTa was performed in parasternal long axis using 3DE. Eccentricity Index was calculated using the lateral and anterior-posterior LVOTd. SV was obtained by four different methods: (1) 2D gray scale, (2) 2D color, (3) LVOTa × LVOT velocity time integral, and (4) SV by Simpson's biplane method. Gray scale LVOTd was significantly smaller compared to LVOTd obtained with CD (P < 0.05). Significant differences occurred between LVOTa gray scale and CD (3.29 ± 0.74 cm(2) vs 3.67 ± 0.70 cm(2) , P < 0.05) and between LVOTa calculated by gray scale in comparison to 3DE planimetry; (3.29 ± 0.74 cm(2) vs 3.61 ± 0.89 cm(2) , P = 0.011). Half of the subjects had at least 17% difference between the lateral and anterior-posterior LVOTd. There were significant differences between SV by 2D gray scale and 2D CD (82.8 ± 17.1 mL vs 92.4 ± 16.8 mL, P < 0.05) and between 2D gray scale and 3DE planimetry (82.8 ± 17.1 mL vs 90.7 ± 19.8 mL, P = 0.025). Our study demonstrates LVOT being frequently elliptical. SV and LVOTa were found to be similar when comparing 2DE CD and 3DE planimetry and showed higher values in comparison to 2DE gray scale, which suggests 2DE CD to be an alternative approach for SV assessment.

Aortoiliac CT Angiography for Planning Transcutaneous Aortic Valve Implantation: Aortic Root Anatomy and Frequency of Clinically Significant Incidental Findings

The purpose of this article is to assess aortic root and iliofemoral vessel anatomy and the frequency of clinically significant incidental findings on aortoiliac CT angiography (CTA) performed for planning of transcutaneous aortic valve implantation. Aortoiliac CTA studies of 207 patients scheduled for transcutaneous aortic valve implantation were analyzed. Anatomic dimensions relevant to the interventional procedure, including diameter of the aortic annulus and sinus of Valsalva, distance between aortic annulus and coronary ostia, coronary leaflet length, left ventricular outflow tract diameter, and vessel diameter of iliac arteries, were analyzed. Clinically significant incidental findings were recorded. The mean (± SD) maximum and minimum diameters of the aortic annulus were 29 ± 3.9 mm and 23.5 ± 4.1 mm, respectively. The mean distances between aortic annulus and the ostium of the left and right coronary artery were 13.5 ± 3.2 mm and 14.8 ± 3.9 mm, respectively. The mean maximum and minimum diameters of the left ventricular outflow tract were 27 ± 4 mm and 1.9 ± 4 mm, respectively. The mean diameter of the sinus of Valsalva was 33.4 ± 5.1 mm. The mean diameters of the right and left external iliac artery were 8 ± 1 and 8 ± 2 mm, respectively. Almost half the patients (101/207) had clinically significant incidental findings, including noncalcified pulmonary nodules larger than 8 mm (n = 7), pulmonary embolism (n = 3), or aortic aneurysm (n = 12). Aortoiliac CTA provides relevant information on aortic root and iliofemoral vessel anatomy for preinterventional planning. CTA reveals clinically significant incidental findings in a high number of patients considered for transcutaneous aortic valve implantation, which may have a significant impact on patient selection.

Haemodynamics using transthoracic echocardiography in healthy pregnant and non‐pregnant baboons (Papio hamadryas)

To determine systolic and diastolic function using transthoracic echocardiography in the baboon (Papio hamadryas). Transthoracic echocardiography was performed in eight non-pregnant female and six pregnant baboons according to American Society of Echocardiography recommendations. Haemodynamic measurements were obtained from fourteen baboons. Compared to non-pregnant baboons, pregnant baboons demonstrated: (mean ± SD, pregnant vs. healthy) increased cardiac output (1615 ± 121 ml/minutes vs. 1317 ± 134 ml/minutes P = 0.001) due to an increased heart rate [120 ± 11 beats per minute (BPM) vs. 105 ± 6 BPM P = 0.018]. The inter-observer and intra-observer variability (mean difference ± SD) for the left ventricular outflow tract diameter was 0.05 ± 0.07 cm and 0.01 ± 0.03 cm respectively. There was minimal impact to the animal's daily activities. Transthoracic echocardiography was applicable and reproducible for the assessment of haemodynamics in baboons thus enabling translation of animal results to human studies.

Frequency of Cardiac Conduction Disturbances After Balloon Aortic Valvuloplasty

Disturbances in atrioventricular conduction are well-recognized complications of transcatheter aortic valve replacement. Percutaneous balloon aortic valvuloplasty (BAV) is a requisite step in transcatheter aortic valve replacement; however, the contribution of the BAV to atrioventricular conduction disturbances has not been elucidated. The present analysis was undertaken to ascertain the incidence and type of electrocardiographic changes associated with BAV and to consider the role of BAV in the conduction abnormalities after transcatheter aortic valve replacement. In 271 consecutive patients with symptomatic, severe aortic stenosis undergoing BAV, a standard 12-lead electrocardiogram was obtained before and serially after the procedure. Each was examined by experienced electrocardiographers. The cohort was divided into 2 groups with regard to the post-BAV appearance of conduction disturbances. The clinical and procedural characteristics of patients with these disturbances were compared to those in whom no conduction disturbance appeared. After BAV, 23 patients (8.5%) met the study definition of "new conduction defect": 4 patients (1.5%) required permanent pacemaker implantation for advanced atrioventricular block. New left bundle branch block appeared in 9 (3.3%) and left anterior hemiblock in 7 (2.6%). New right bundle branch block appeared in 2 and left posterior hemiblock in 1. No significant difference was found in the clinical or procedural characteristics. The ratio of the balloon size to the left ventricular outflow tract diameter was 1.21 ± 1.6 in those with new conduction defects and 1.15 ± 0.12 (p = 0.032) in those without. In conclusion, BAV is associated with a low incidence of cardiac conduction disturbances and a requirement for permanent ventricular pacing. The size of the valvuloplasty balloon should be carefully selected to avoid oversizing, which can lead to the development of postprocedure conduction disturbances.

Range of right heart measurements in top-level athletes: The training impact

ObjectivesTo explore the full range of right heart dimensions and the impact of long-term intensive training in athletes. BackgroundAlthough echocardiography has been widely used to distinguish the athlete's heart from pathologic left ventricular (LV) hypertrophy, only few reports have described right ventricular (RV) and right atrial (RA) adaptations to extensive physical exercise. Methods650 top-level athletes [395 endurance- (ATE) and 255 strength-trained (ATS); 410 males (63.1%); mean age 28.4±10.1; 18–40years] and 230 healthy age- and sex-comparable controls underwent a transthoracic echocardiographic exam. Along with left heart parameters, right heart measurements included: RV end-diastolic diameters at the basal and mid-cavity level; RV base-to-apex length; RV proximal and distal outflow tract diameters; RA long and short diameters; and RA area. Tricuspid annular plane systolic excursion and RV tissue Doppler systolic peak velocity were assessed as indexes of RV systolic function. Pulmonary artery systolic pressure (PASP) was estimated from the peak tricuspid regurgitant velocity. ResultsATS showed increased sum of wall thickness and relative wall thickness, whereas left atrial volume, LV end-diastolic volume, LV stroke volume and PASP were significantly higher in ATE. RV and RA measurements were all significantly greater in ATE than in ATS and controls. ATE also showed improved early diastolic RV function, whereas RV systolic indexes were comparable among groups. On multivariate analysis, type and duration of training (p<0.01), PASP (p<0.01) and LV stroke volume (p<0.001) were the only independent predictors of the main RV and RA dimensions in athletes. ConclusionsThis study delineates the upper limits of RV and RA dimensions in highly-trained athletes. Right heart measurements were all significantly greater in elite endurance-trained athletes than in age- and sex-matched strength athletes and controls. This should be considered as a “physiologic phenomenon” when evaluating athletes for sports eligibility.

Mitral Valve Abnormalities Identified by Cardiovascular Magnetic Resonance Represent a Primary Phenotypic Expression of Hypertrophic Cardiomyopathy

Whether morphological abnormalities of the mitral valve represent part of the hypertrophic cardiomyopathy (HCM) disease process is unresolved. Therefore, we applied cardiovascular magnetic resonance to characterize mitral valve morphology in a large HCM cohort. Cine cardiac magnetic resonance images were obtained in 172 HCM patients (age, 42±18 years; 62% men) and 172 control subjects. In addition, 15 HCM gene-positive/phenotype-negative relatives were studied. Anterior mitral leaflet (AML) and posterior mitral leaflet lengths were greater in HCM patients than in control subjects (26±5 versus 19±5 mm, P<0.001; and 14±4 versus 10±3 mm, P<0.001, respectively), including 59 patients (34%) in whom AML length alone, posterior mitral leaflet length alone, or both were particularly substantial (>2 SDs above controls). Leaflet length was increased compared with controls in virtually all HCM age groups, including young patients 15 to 20 years of age (AML, 26±5 versus 21±4 mm; P=0.0002) and those ≥60 years of age (AML, 26±4 versus 19±2 mm; P<0.001). No relation was evident between mitral leaflet length and LV thickness or mass index (P=0.09 and P=0.16, respectively). A ratio of AML length to LV outflow tract diameter of >2.0 was associated with subaortic obstruction (P=0.001). In addition, AML length in 15 genotype-positive relatives without LV hypertrophy exceeded that of matched control subjects (21±3 versus 18±3 mm; P<0.01). In HCM, mitral valve leaflets are elongated independently of other disease variables, likely constituting a primary phenotypic expression of this heterogeneous disease, and are an important morphological abnormality responsible for LV outflow obstruction in combination with small outflow tract dimension. These findings suggest a novel role for cardiac magnetic resonance in the assessment of HCM.

Hypertrophic obstructive cardiomyopathy: alcohol septal ablation

Alcohol septal ablation (ASA) was introduced in 1994 as an alternative to septal myectomy for patients with hypertrophic obstructive cardiomyopathy and symptoms refractory to medical therapy. This procedure alleviates symptoms by producing a targeted, limited infarction of the upper interventricular septum, resulting in an increase in left ventricular outflow tract (LVOT) diameter, a decrease in LVOT gradient, and regression of the component of LV hypertrophy that is due to pressure overload. Clinical success, with improvement in symptoms and reduction in gradient, is achieved in the great majority of patients with either resting or provocable LVOT obstruction. The principal morbidity of the procedure is complete heart block, resulting in some patients in the requirement for a permanent pacemaker. The introduction of myocardial contrast echocardiography as a component of the ASA procedure has contributed to the induction of smaller myocardial infarctions with lower dosages of alcohol and, in turn, fewer complications. Non-randomized comparisons of septal ablation and septal myectomy have shown similar mortality rates and post-procedure New York Heart Association class for the two procedures.

286 – Percutaneous right outflow tract valve implantation: substrate matters

Percutaneous pulmonary valve insertion has been recently introduced in clinical setting. Patient selection is widely accepted. These candidates are however heterogeneous, in regard of heart defects, and type of surgical right ventricular outflow tract (RVOT) reconstruction. It is presently unclear in the literature if type of surgical reconstruction matters for the success of the pulmonary valve insertion. Our goal was to compare the hemodynamic results of percutaneous pulmonary valve in patients with homografts, prosthetic conduit or RVOT reconstructed with patch. We reviewed patients included over the last 6 months in the prospective study (REVALV) for patients undergoing RVOT intervention for severe stenosis and/or insufficiency. Only valved stent group is analyzed here. All patients undergoing valved stent implantation are previously pre-stented with a bare metal stent according to present recommendations. Thirty-seven patients were included, distributed in three groups according to type of RVOT reconstruction (homograft REVALV is a multicentric prospective study for patients undergoing RVOT intervention for severe stenosis and/or insufficiency. Patients are distributed in three groups according to type of RVOT reconstruction (homograft, n = 10; prosthetic conduit, n = 20; RVOT enlargement by patch, n = 7). Overall, all groups were similar in RV to AP gradient improvement (after pre-stenting mean 30,79 vs 28 p = NS; final result mean 23,71 vs 28,17, p = NS), RV to aorta pressures ratio (after pre-stenting 0,187 vs 0,3117 p = NS; final result man 0,315 vs 0,317, p = NS). If considering non-extensible synthetic tubes we observe that RV-to-AP improvement is significantly worst to the rest of the group (mean 7,07 vs 0,17, p = 0,005). When focusing on outflow tract diameter, results did not differ in homograft group and patch group. In contrast, diameter did play a role in those patients having a synthetic tube, with a cut-off at 20 mm diameter. Below 20 mm, relieve of outflow tract gradient was significantly worse than for bigger conduits. Pulmonary valve insertion is efficient in all type of RVOT reconstruction at least in the short term. The diameter of the conduits did not play a role in RVOT obstruction relief as long as surgical substrates are homografts or patch enlargement. In patients with prosthetic conduits, size matters. In non-extensible synthetic tubes results are worst. Reduced distensibility and progressive diameter reduction may lead to not consider these patients as good candidates for this procedure.

120 Superiority of CT scan over transthoracic echocardiography in predicting aortic regurgitation after TAVI

Paravalvular aortic regurgitation (AR) occurs in up to 86% of patients undergoing Transcatheter Aortic Valve Implantation (TAVI). Its prevalence remains unchanged after one year follow-up but its determinants are unclear. We sought to evaluate the impact of annulus measurement by transthoracic echocardiography (TTE) and by CT scan on the occurrence of AR. The study included 43 symptomatic patients (83 ± 8 years, 72% in NYHA ≥ III) with severe aortic stenosis [0.76 ± 0.19 cm 2 , mean gradient 42 ± 14 mmHg] who underwent TAVI using CoreValve® LLC Percutaneous Aortic Valve Implantation System, Medtronic, Minneapolis USA. Left ventricular outflow tract (LVOT) area was computed from LVOT diameter (21 ± 2 mm) by TTE using a spherical model and from CT using an ellipsoidal model according to the larger (25 ± 3 mm) and the smaller outflow tract diameters (22 ± 3 mm). These data were compared to the prosthesis area and the occurrence of AR after TAVI. In patients with AR greater or equal to 2/4 (32%), LVOT area measured by CT was significantly greater as compared to patients with no or mild AR (478 ± 65 mm 2 vs. 411 ± 85 mm 2 , p = 0.009). Furthermore, the difference between actual prosthesis area and LVOT area measured by CT scan was significantly smaller (113 ± 55 vs. 171 ± 67, p = 0.009) in patients with significant AR (≥2/4) after TAVI. In contrast, LVOT area from TTE did not correlate with AR severity. CT scan is more accurate than TTE for calculating LVOT area for prosthesis sizing before TAVI in order to avoid post-implantation AR.

Does a Large Left Ventricular Outflow Tract Diameter Influence Calculated Dimensionless Index? Implications for Assessment of Aortic Stenosis Severity

Male, n (%) 28 (88%) 21 (21%) <0.001 Age (years), mean ± SD 73.0 ± 11.9 74.3 ± 15.1 0.65 Body surface area (m2), mean ± SD 1.94 ± 0.18 1.62 ± 0.35 <0.001 LVOT diameter (cm), mean ± SD 2.50 ± 0.10 1.92 ± 0.09 <0.001 AVA (cm2), mean ± SD 0.78 ± 0.13 0.62 ± 0.14 <0.001 Indexed AVA (cm2/m2), mean ± SD 0.40 ± 0.08 0.38 ± 0.09 0.16

Cardiac index measurements by transcutaneous Doppler ultrasound and transthoracic echocardiography in adult and pediatric emergency patients

Non-invasive hemodynamic monitoring may facilitate resuscitation in critically ill patients. Validation studies examining a transcutaneous Doppler ultrasound technology, USCOM-1A, using pulmonary artery catheter as the reference standard showed varying results. In this study, we compared non-invasive cardiac index (CI) measurements by USCOM-1A with transthoracic echocardiography (TTE). This study was a prospective, observational cohort study at a university tertiary-care emergency department, enrolling a convenience sample of adult and pediatric patients. Paired measures of CI, stroke volume index (SVI), aortic outflow tract diameter (OTD), velocity time integral (VTI) were obtained using USCOM-1A and TTE. Pearson's correlation and Bland-Altman analyses were performed. One-hundred and sixteen subjects were enrolled, with obtainable USCOM-1A CI measurements for 99 subjects (55 adults age 50 +/- 20 years and 44 children age 11 +/- 4 years) in the final analysis. Cardiac, gastrointestinal and infectious illnesses were the most common presenting diagnostic categories. The reference standard TTE measurements of CI, SVI, OTD, and VTI in all subjects were 3.08 +/- 1.18 L/min/m(2), 37.10 +/- 10.91 mL/m(2), 1.92 +/- 0.36 cm, and 20.36 +/- 4.53 cm, respectively. Intra-operator reliability of USCOM-1A CI measurements showed a correlation coefficient of r = 0.79, with 11 +/- 22% difference between repeated measures. The bias and limits of agreement of USCOM-1A compared to TTE CI were 0.58 (-1.48 to 2.63) L/min/m(2). The percent difference in CI measurements with USCOM-1A was 31 +/- 28% relative to TTE measurements. The USCOM-1A hemodynamic monitoring technology showed poor correlation and agreement to standard transthoracic echocardiography measures of cardiac function. The utility of USCOM-1A in the management of critically ill patients remains to be determined.

085 Two dimensional right ventricular size assessments in a healthy population—time to index?: Abstract 085 Table 1

<h3>Background</h3> Two dimensional (2D) measurements of the right ventricle (RV) were first validated by Foale <i>et al</i> in 1986 using a cohort of 41 volunteers. The British Society of Echocardiography (BSE) published the current guidelines for chamber quantification of the RV. These ranges are taken from recommendations made between the American and European Society of echocardiography³, which itself is an adaptation of Foales’ initial findings. BSE guidelines for the assessment of 2D RV are based on absolute dimensions rather than values indexed to body surface area (BSA). <h3>Aim</h3> To evaluate RV dimensions in a group of healthy volunteers. <h3>Methods</h3> One hundred and fifty three subjects aged between 21 and 71 (mean 44 yrs) were enrolled and following screening (12 lead ECG, health questionnaire and physical examination) underwent a standardised echocardiogram. Height and weight were measured to estimate BSA. Standard 2D echocardiography assessed the right ventricular outflow tract diameter above the aortic valve (RVOT1), above the pulmonary valve (RVOT2), the RV basal (RVD1) and RV mid (RVD2) diameter, the RV base to apex length (RVD3), RV diastolic (RVDA) and systolic (RVSA) area. Absolute measurements and results corrected for BSA are presented as mean (2SD). Ten randomly chosen studies were analysed on separate occasions by a second accredited echocardiographer providing an Inter observer agreement index (IOA) and coefficient of variation (CoV). Ethical approval was obtained. <h3>Results</h3> The IOA shows high percentage agreement (92.81–97.92%) for 2D caliper measurements. Satisfactory (&lt;15%) CoV results were also obtained within the same measurements. A lower IOA (83.38–91.33%) and higher CoV (20.73–20.83%) were calculated for RVDA and RVSA. All measurements were normally distributed. When compared to current guidelines up to 52% of all absolute RV dimensions measured were outside the reference range. However, when indexed to BSA this fell to a maximum of 13% using the indexed range initially proposed by Foale <i>et al</i>. Due to image quality not every measurement was available on all volunteers. <h3>Conclusion</h3> Indexing echocardiographic measurements to BSA is standard practice with indices of normality already established for the left ventricle. We have shown that a substantial degree of individual variability of absolute RV dimensions exists within this clinically normal population. These data suggest that indexing absolute RV dimensions according to BSA would be clinically more valuable and accurate than using absolute RV dimensions alone. Absolute and indexed ranges from our data are shown in abstract 085 table 1.

Transesophageal Echocardiography Cardiac Output in FlowTrak/ Vigileo Study

To the Editor: In the article by Concha et al.1 comparing cardiac output (CO) measurements of the FlowTrak/Vigileo monitor with those obtained by transesophageal echocardiography (TEE), the authors state that they used the transesophageal CO method previously validated by Perrino et al.2 However, an important difference between the validated technique and that used in their study has implications with regard to the interpretation of their findings. Stroke volume by the Doppler method can be understood as the product of blood transit (distance traveled, which is derived from velocity measurements) and the cross-sectional area of the flow stream during systole. Concha et al. chose continuous wave (CW) Doppler measures of blood flow velocity in conjunction with a 2-dimensional measurement of left ventricular outflow tract (LVOT) diameter to calculate the cross-sectional area. This is not the method described by Perrino et al.2 in the cited article, nor is it as Perrino and Maslow describe in the text, “A Practical Approach to Transesophageal Echocardiography.”3 The method validated in the 1998 article does use CW Doppler, but matched to the triangular-shaped aortic valve area, not LVOT area, to best estimate the average cross-sectional area of the flow stream. The concern with using LVOT area is the overestimation of the cross-sectional area of the flow stream across the aortic valve that was assessed by the CW Doppler. The overestimation of cross-sectional area leads to a proportional overestimate of CO. Darmon et al.4 showed that a circular measurement of the aortic valve area overestimates the average cross-sectional area of the flow stream by 36% (3.28 vs 2.41 cm2). Because LVOT area equals or exceeds the area of the aortic valve annulus, Concha et al. substantially overestimate CO by TEE when using LVOT area in conjunction with CW Doppler velocities from the aortic valve. For this reason, a pulsed wave Doppler measurement with the sample volume located within the LVOT is preferred for CO calculations based on LVOT area. The overestimation of CO measurements by the TEE method used by Concha et al. affects their findings because they observed a consistent positive bias; TEE measurements exceeded those derived by FlowTrak/Vigileo (mean TEE CO 6.21 L/min; mean FlowTrak CO 4.84 L/min; mean difference 28%) (Figs. 1 and 2, Table 3). We believe the mean bias between TEE and FlowTrak/Vigileo CO measurements to be substantially less than reported (and perhaps a negative value) because of the TEE CO method used in this study. Interpretation of this study should recognize that the chosen TEE method affects the reported mean bias between techniques but does not alter the SD of the differences between techniques.5 In conclusion, the method used to measure TEE CO described in the study by Concha et al. is not recommended as a reference technique because it will overestimate CO. Interpretation of their results and the performance of the FlowTrak/Vigileo should take into consideration overestimations of TEE CO. William J. Perez, MD, MA Department of Anesthesiology The Ohio State University Medical Center Columbus, Ohio [email protected] Albert C. Perrino, Jr., MD Yale University School of Medicine VA Connecticut Healthcare System New Haven, Connecticut

Factors associated with cardiac conduction disorders and permanent pacemaker implantation after percutaneous aortic valve implantation with the CoreValve prosthesis

Cardiac conduction disorders and requirement for permanent pacemaker implantation (PPI) are not uncommon after surgical aortic valve replacement and have important clinical implications. We aimed to investigate the incidence of cardiac conduction disorders after percutaneous aortic valve implantation (PAVI) and to identify possible clinical factors associated with their development. We studied 34 patients (mean age 80 +/- 8 years, 18 male) who underwent PAVI with the CoreValve bioprosthesis (Corevalve Inc, Irvine, CA). Electrocardiographic evaluation was performed pre- and postprocedurally, and at 1-week and 1-month follow-up. Other clinical variables were obtained from the medical history, echocardiography, and angiography. After PAVI, 7 patients required PPI, all of whom developed total atrioventricular block within 3 days postprocedurally. A smaller left ventricular outflow tract diameter (20.3 +/- 0.5 vs 21.6 +/- 1.8 cm, P = .01), more left-sided heart axis (-20 degrees +/- 29 degrees vs 19 degrees +/- 36 degrees , P = .02), more mitral annular calcification (10 +/- 1 vs 5 +/- 4 mm, P = .008), and a smaller postimplantation indexed effective orifice area (0.86 +/- 0.20 vs 1.10 +/- 0.26 cm(2)/m(2), P = .04) were associated with PPI. The incidence of new left bundle-branch block (LBBB) was 65% and was associated with a deeper implantation of the prosthesis: 10.2 +/- 2.3 mm in the new-LBBB group versus 7.7 +/- 3.1 mm in the non-LBBB group (P = .02). Percutaneous aortic valve implantation with the CoreValve prosthesis results in a high incidence of total atrioventricular block requiring PPI and new-onset LBBB. Preexisting disturbance of cardiac conduction, a narrow left ventricular outflow tract, and the severity of mitral annular calcification predict the need for permanent pacing, whereas the only factor shown to be predictive for new-onset LBBB is the depth of prosthesis implantation.