Optimal Technique for Measurement of Linear Left Ventricular Dimensions

INTRODUCTION

Echocardiographic assessment of the left ventricle (LV) begins with the measurement of linear dimensions that approximate its ellipsoid diameter. These linear dimensions have historically been measured at the basal level of the LV, which is not representative of its true diameter. The objective of this study was to determine the optimal level to measure LV cavity dimensions to more accurately estimate its size and mass.

METHODS

The derivation study included 75 patients who had a clinically indicated cardiac magnetic resonance (CMR) exam for ischemic heart disease (n = 15), nonischemic cardiomyopathy (n = 25), or normal studies (n = 35). The three-chamber bright blood cine sequence was analyzed using a custom MATLAB program to measure the LV cavity diameter and wall thickness at 15 equidistant levels from base to apex. The linear measurements from each of these levels were compared against the CMR volumetric reference standard. The validation study included 100 patients who had a clinically indicated echocardiogram and CMR within 3 days for ischemic heart disease (n = 20), nonischemic cardiomyopathy (n = 44), and normal or near-normal studies (n = 36). The parasternal long-axis cine sequence was analyzed to measure the LV cavity diameter and wall thickness at the traditional basal level and the midventricular level, which were compared against the CMR volumetric reference standard.

RESULTS

In both the derivation and validation studies, the midventricular linear dimensions, defined as those located at the true (maximal) diameter of the LV ellipsoid cavity, were found to be more closely correlated with the volumetric reference standard for LV mass, LV end-diastolic size, and LV ejection fraction.

CONCLUSIONS

Measurement of linear dimensions at the midventricular level better reflects the ellipsoid geometry of the LV cavity and provides a more accurate estimate of LV mass, size, and systolic function as compared with the traditionally recommended basal level.

Association Between Transthoracic Echocardiography Appropriateness and Echocardiographic Findings

BACKGROUND

The association between appropriate use criteria and echocardiographic findings in patients with chronic cardiovascular diseases is unknown.

METHODS

As a substudy of the Echo WISELY (Will Inappropriate Scenarios for Echocardiography Lessen Significantly) trial, 9,230 transthoracic echocardiographic (TTE) examinations from six Ontario academic hospitals were linked to a registry of echocardiographic findings. The TTE studies were rated appropriate), rarely appropriate, or may be appropriate according to the 2011 appropriate use criteria. TTE findings of appropriately ordered examinations were compared with those of rarely appropriate examinations for specific disease subsets, including heart failure and valvular heart disease.

RESULTS

There were 7,574, 1,087, and 569 TTE examinations ordered for appropriate, rarely appropriate, and may be appropriate indications, and of the 7,574 appropriate studies, 6,399 were ordered for specific indications and 1,175 for general indications. TTE examinations ordered for general indications had lower rates of left ventricular dysfunction (19.6% vs 9.1%, P < .001) and moderate to severe aortic stenosis (15.5% vs 2.6%, P < .001). Of the 2,395 TTE examinations ordered for patients with heart failure, appropriately ordered studies were more likely to result in left ventricular segmental abnormality (37.0% vs 24.9%, P = .012) but similar rates of right ventricular dilatation (15.4% vs 14.7%, P = .79), right ventricular dysfunction (14.8% vs 11.3%, P = .22), and moderate to severe mitral regurgitation (12.1% vs 9.2%, P = .35). Of the 2,859 studies ordered to assess valvular heart disease, appropriately ordered studies were significantly more likely to find moderate to severe valvular pathology, including aortic stenosis (30.4% vs 24.6%, P = .008), aortic regurgitation (8.9% vs 1.6%, P < .001), mitral stenosis (6.7% vs 3.1%, P = .002), and mitral regurgitation (16.1% vs 6.1%, P < .001), but similar rates of tricuspid regurgitation (11.2% vs 13.0%, P = .60).

CONCLUSIONS

Overall, appropriately ordered TTE examinations for heart failure and valvular heart disease were significantly more likely to have abnormal findings than rarely appropriate examinations. TTE studies ordered for general indications had fewer, although still a significant proportion, of abnormalities compared with studies ordered for specific indications.

Catecholamine response to exercise in patients with non-obstructive hypertrophic cardiomyopathy

KEY POINTS

Intense physical activity, a potent stimulus for sympathetic nervous system activation, is thought to increase the risk of malignant ventricular arrhythmias among patients with hypertrophic cardiomyopathy (HCM). As a result, the majority of patients with HCM deliberately reduce their habitual physical activity after diagnosis and this lifestyle change puts them at risk for sequelae of a sedentary lifestyle: weight gain, hypertension, hyperlipidaemia, insulin resistance, coronary artery disease, and increased morbidity and mortality. We show that plasma catecholamine levels remain stably low at exercise intensities below the ventilatory threshold, a parameter that can be defined during cardiopulmonary exercise testing, but rise rapidly at higher intensities of exercise. These findings suggest that cardiopulmonary exercise testing may be a useful tool to provide an individualized moderate-intensity exercise prescription for patients with HCM.

ABSTRACT

Intense physical activity, a potent stimulus for sympathetic nervous system activation, is thought to increase the risk of malignant ventricular arrhythmias among patients with hypertrophic cardiomyopathy (HCM). However, the impact of exercise intensity on plasma catecholamine levels among HCM patients has not been rigorously defined. We conducted a prospective observational case-control study of men with non-obstructive HCM and age-matched controls. Laboratory-based cardiopulmonary exercise testing coupled with serial phlebotomy was used to define the relationship between exercise intensity and plasma catecholamine levels. Compared to controls (C, n = 5), HCM participants (H, n = 9) demonstrated higher left ventricular mass index (115 ± 20 vs. 90 ± 16 g/m² , P = 0.03) and maximal left ventricular wall thickness (16 ± 1 vs. 8 ± 1 mm, P < 0.001) but similar body mass index, resting heart rate, peak oxygen consumption (H = 40 ± 13 vs. C = 42 ± 7 ml/kg/min, P = 0.81) and heart rate at the ventilatory threshold (H = 78 ± 6 vs. C = 78 ± 4% peak heart rate, P = 0.92). During incremental effort exercise in both groups, concentrations of adrenaline and noradrenaline were unchanged through low- and moderate-exercise intensity until reaching a catecholamine threshold (H = 82 ± 4 vs. C = 85 ± 3% peak heart rate, P = 0.86) after which levels of both molecules rose rapidly. In patients with mild non-obstructive HCM, plasma catecholamine levels remain stably low at exercise intensities below the ventilatory threshold but rise rapidly at higher intensities of exercise. Routine cardiopulmonary exercise testing may be a useful tool to provide an individualized moderate-intensity exercise prescription for patients with HCM.

Endurance Exercise Training Attenuates Natriuretic Peptide Release During Maximal Effort Exercise: Biochemical Correlates of the "Athlete's Heart"

Endurance exercise training (ET) stimulates eccentric left ventricular hypertrophy (LVH) with left atrial dilation. To date, the biochemical correlates of exercise-induced cardiac remodelling (EICR) remain incompletely understood. Collegiate male rowers (n = 9) were studied with echocardiography and maximal-effort cardiopulmonary exercise testing (MECPET) before and after 90 days of ET intensification. Mid-regional pro-atrial natriuretic peptide (MR-proANP), N-terminal pro B-type natriuretic peptide (NT-proBNP), and high-sensitivity troponin T (hscTn) were measured at rest, peak MECPET, and 60 minutes post-MECPET at both study time points. ET resulted in eccentric LVH (LV mass = 102 ± 8 vs. 110 ± 11 g/m², p=0.001; relative wall thickness = 0.36 ± 0.04 vs. 0.37 ± 0.04, p=0.103), left atrial dilation (74 ± 18 vs. 84 ± 15 mL, p<0.001), and increased exercise capacity (peak VO₂ = 53.0 ± 5.9 vs. 67.3 ± 8.2 ml/kg/min, p<0.001). LV remodelling was characterized by an approximate 7% increase in LV wall thickness but only a 3% increase in LV chamber radius. The magnitude of natriuretic peptide release, examined as percent change from rest to peak exercise, was significantly lower for both MR-proANP (115 [95, 127]% vs. 78 [59, 87]%, p=0.04) and NT-proBNP (46 [31, 70]% vs. 27 [25, 37]%, p=0.02) after ET. Rowing-based ET and corollary EICR appear to result in an attenuated natriuretic peptide response to maximal effort exercise. This may occur as a function of decreased cardiac wall stress after ET as seen by disproportionally higher ventricular wall thickening compared to chamber dilation.

Aortic valve replacement associated with survival in severe regurgitation and low ejection fraction

OBJECTIVES

Although guidelines support aortic valve replacement (AVR) in patients with severe aortic regurgitation (AR) and left ventricular ejection fraction (LVEF) <50%, severe left ventricular dysfunction (LVEF <35%) is thought to confer high surgical risk. We sought to determine if a survival benefit exists with AVR compared with medical management in this high-risk, relatively rare population.

METHODS

A large institutional echocardiography database was queried to identify patients with severe AR and LVEF <35%. Manual chart review was performed. Due to small sample size and population heterogeneity, corrected group prognosis method was applied, which calculates the adjusted survival curve for each individual using fitted Cox proportional hazard model. Average survival adjusted for comorbidities and age was then calculated using the weighted average of the individual survival curves.

RESULTS

Initially, 2 54 614 echocardiograms were considered, representing 1 45 785 unique patients, of which 40 patients met inclusion criteria. Of those, 18 (45.0%) underwent AVR and 22 (55.0%) were managed medically. Absolute mortality was 27.8% in the AVR group and 91.2% in the medical management group. After multivariate adjustment, end-stage renal disease (HR=17.633, p=0.0335) and peripheral arterial disease (HR=6.050, p=0.0180) were associated with higher mortality. AVR was associated with lower mortality (HR=0.143, p=0.0490). Mean follow-up time of the study cohort was 6.58 years, and mean survival for patients undergoing AVR was 6.31 years.

CONCLUSIONS

Even after adjustment for clinical characteristics and patient age, AVR is associated with higher survival for patients with low LVEF and severe AR. Although treatment selection bias cannot be completely eliminated by this analysis, these results provide some evidence that surgery may be associated with prolonged survival in this high-risk patient group.

Cardiovascular response to prescribed detraining among recreational athletes

Exercise-induced cardiac remodeling (EICR) and the attendant myocardial adaptations characteristic of the athlete’s heart may regress during periods of exercise reduction or abstinence. The time course and mechanisms underlying this reverse remodeling, specifically the impact of concomitant plasma volume (PV) contraction on cardiac chamber size, remain incompletely understood. We therefore studied recreational runners ( n = 21, age 34 ± 7 yr; 48% male) who completed an 18-wk training program (~7 h/wk) culminating in the 2016 Boston Marathon after which total exercise exposure was confined to <2 h/wk (no single session >1 h) for 8 wk. Cardiac structure and function, exercise capacity, and PV were assessed at peak fitness (10–14 days before) and at 4 wk and 8 wk postmarathon. Mixed linear modeling adjusting for age, sex, V̇o2peak, and marathon finish time was used to compare data across time points. Physiological detraining was evidenced by serial reductions in treadmill performance. Two distinct phases of myocardial remodeling and hematological adaptation were observed. After 4 wk of detraining, there were significant reductions in PV (Δ −6.0%, P < 0.01), left ventricular (LV) wall thickness (Δ −8.1%, <0.05), LV mass (Δ −10.3%, P < 0.001), and right atrial area (Δ −8.2%, P < 0.001). After 8 wk of detraining, there was a significant reduction in right ventricle chamber size (end-diastolic area Δ = −8.0%, P < 0.05) without further concomitant reductions in PV or LV wall thickness. Abrupt reductions in exercise training stimulus result in a structure-specific time course of reverse cardiac remodeling that occurs largely independently of PV contraction.

NEW & NOTEWORTHY Significant reverse cardiac remodeling, previously documented among competitive athletes, extends to recreational runners and occurs with a distinct time course. Initial reductions in plasma volume and left ventricular (LV) mass, driven by reductions in wall thickness, are followed by contraction of the right ventricle. Consistent with data from competitive athletes, LV chamber volumes appear less responsive to detraining and may be a more permanent adaptation to sport.

Assessment of Tricuspid Annular Motion by Speckle Tracking in Anesthetized Patients Using Transesophageal Echocardiography

BACKGROUND

The perioperative assessment of right ventricular (RV) function remains a challenge. Tricuspid annular plane systolic excursion (TAPSE) using M-mode is a widely used measure of RV function. However, accurate alignment of the ultrasound beam with the direction of annular movement can be difficult with transesophageal echocardiography (TEE) to measure TAPSE, precluding effective use of M-mode to measure annular excursion. Tracking of specular reflectors in the myocardium may provide an angle-independent method to assess annular motion with TEE. We hypothesized that TEE speckle tracking of the lateral tricuspid annular motion represents a comparable measurement to the well-validated M-mode TAPSE on transthoracic echocardiogram (TTE), and may be considered as a reasonable alternative to TAPSE.

METHODS

This is a prospective, observational cohort study. We included all patients, who were in sinus rhythm, with a preoperative TTE within 3 months of scheduled cardiac surgery that required intraoperative TEE. Tissue motion annular displacements (TMAD) of the lateral (L), septal (S), and midpoint (M) tricuspid annulus were measured (QLAB Cardiac Motion Quantification; Philips Medical, Andover, MA) after induction of general anesthesia. This was compared to the preoperative M-mode TAPSE on TTE.

RESULTS

Seventy-two consecutive patients who met eligibility requirements were enrolled from September to November 2016. Twelve were excluded due to poor image quality, allowing TMAD to be analyzed in 60 patients. TMAD was analyzed offline and TMAD analysis was able to track tricuspid annular motion in all patients. The mean TMAD (L), TMAD (S), and TMAD (M) were 17.4 ± 5.2, 10.2 ± 4.8, and 14.2 ± 4.8 mm, respectively. TMAD (L) showed close correlation with M-mode TAPSE on TTE (r = 0.87, 95% confidence interval, 0.79-0.92; P < .01). All patients with a preoperative TAPSE <17 mm had a TMAD (L) <17 mm, while 71% of those with a TAPSE ≥ 17 mm had a TMAD (L) ≥ 17 mm. There was strong positive correlation between TMAD (L) and intraoperative RV fractional area change (r = 0.86, 95% confidence interval, 0.77-0.91; P < .01). Reproducibility analysis of TMAD within and across observers showed excellent correlation.

CONCLUSIONS

TMAD is a quick and angle-independent method to quantitatively assess RV longitudinal function by TEE. It correlates strongly with M-mode TAPSE on TTE. Because TMAD and TAPSE were not simultaneously measured in this study, their correlation is subject to differences in loading conditions, general anesthesia, and changes in the disease process. TMAD may be easily applied in routine clinical settings and its role in the perioperative environment deserves to be further explored.

Blood Pressure and LV Remodeling Among American-Style Football Players

OBJECTIVES

This study sought to determine the relationships among American-style football (ASF) participation, acquired left ventricular (LV) hypertrophy, and LV systolic function as assessed using contemporary echocardiographic parameters.

BACKGROUND

Participation in ASF has been associated with development of hypertension and LV hypertrophy. To what degree these processes impact LV function is unknown.

METHODS

This was a prospective, longitudinal cohort study evaluating National Collegiate Athletic Association Division I football athletes stratified by field position (linemen: n = 30; vs. nonlinemen, n = 57) before and after a single competitive season, using transthoracic echocardiography. LV systolic function was measured using complementary parameters of global longitudinal strain (GLS) (using 2-dimensional speckle-tracking) and ejection fraction (EF) (2-dimensional biplane).

RESULTS

ASF participation was associated with field position-specific increases in systolic blood pressure (SBP) (a Δ SBP of 10 ± 8 mm Hg in linemen vs. a Δ SBP of 3 ± 7 mm Hg in nonlinemen; p < 0.001) and an overall increase in incident LV hypertrophy (pre-season = 8% vs. post-season = 25%, p < 0.05). Linemen who developed LV hypertrophy had concentric geometry (9 of 11 [82%]) with decreased GLS (Δ = -1.1%; p < 0.001), whereas nonlinemen demonstrated eccentric LV hypertrophy (8 of 10 [80%]) with increased GLS (Δ = +1.4%; p < 0.001). In contrast, LV ejection fraction in the total cohort, stratified by field position, was not significantly affected by ASF participation. Among the total cohort, lineman field position, post-season weight, SBP, average LV wall thickness, and relative wall thickness were all independent predictors of post-season GLS.

CONCLUSIONS

ASF participation at a lineman field position may lead to a form of sport-related myocardial remodeling that is pathologic rather than adaptive. Future study will be required to determine if targeted efforts to control blood pressure, minimize weight gain, and to include an element of aerobic conditioning in this subset of athletes may attenuate this process and translate into tangible downstream health benefits.

New considerations in the assessment of aortic stenosis

Calcific aortic stenosis (AS) is one of the most common acquired valvular heart diseases in industrialized nations. It is a slowly progressive disease and with the aging population, the prevalence of AS is expected to increase. Doppler echocardiography is used to classify patients based on severity of stenosis. Research efforts on how to better identify and risk-assess these patients are currently underway using advanced imaging modalities and serum biomarkers. Thus far, medications for AS prevention have been unsuccessful. As technology progresses, the assessment of AS will transition from one heavily weighed on echocardiographic gradients to one of active surveillances with multimodality imaging, serum biomarkers and genetic assessment.