Differences in myocardial strain between pectus excavatum patients and healthy subjects assessed by cardiac MRI: a pilot study

The influence of pectus excavatum on cardiac kinetics and function in otherwise healthy individuals: A systematic review

BACKGROUND

A number of anterior chest wall deformities, most notably pectus excavatum (PE), may have a detrimental effect on cardiac motion and function. Interpretation of transthoracic echocardiography (TTE) and speckle-tracking echocardiography (STE) results may be hampered by the possible influence of PE on cardiac kinetics.

METHODS

A comprehensive search of all articles assessing cardiac function in PE individuals was carried out. Inclusion criteria were: 1) individuals aged >10 years; 2) studies providing objective assessment of chest deformity (Haller index). Studies that measured myocardial strain parameters in PE patients were also included.

RESULTS

The search (EMBASE and Medline) yielded a total of 392 studies, 36 (9.2%) of which removed as duplicates; a further 339 did not meet inclusion criteria. The full-texts of 17 studies were then analyzed. All studies concordantly reported impaired right ventricular volumes and function. With respect to left ventricle (LV), TTE studies uniformly demonstrated a significant impairment in conventional echoDoppler indices in PE individuals, whereas STE studies provided conflicting results. Importantly, LV functional alterations promptly reverted upon surgical correction of chest defect. In subjects with PE of mild-to-moderate severity, we observed that degree of anterior chest wall deformity, as noninvasively assessed by modified Haller index (MHI), was strongly associated with myocardial strain magnitude, in heterogenous cohorts of otherwise healthy PE individuals.

CONCLUSIONS

Clinicians should be aware that in PE individuals, TTE and STE results may not always be indicative of intrinsic myocardial dysfunction, but may be, at least in part, influenced by artifactual and/or external chest shape determinants.

Evaluating Cardiac Lateralization by MRI to Simplify Estimation of Cardiopulmonary Impairment in Pectus Excavatum

BACKGROUND

The severity of pectus excavatum is classified by the Haller Index (HI) and/or Correction Index (CI). These indices measure only the depth of the defect and, therefore, impede a precise estimation of the actual cardiopulmonary impairment. We aimed to evaluate the MRI-derived cardiac lateralization to improve the estimation of cardiopulmonary impairment in Pectus excavatum in connection with the Haller and Correction Indices.

METHODS

This retrospective cohort study included a total of 113 patients (mean age = 19.03 ± 7.8) with pectus excavatum, whose diagnosis was verified on cross-sectional MRI images using the HI and CI. For the development of an improved HI and CI index, the patients underwent cardiopulmonary exercise testing to assess the influence of the right ventricle's position on cardiopulmonary impairment. The indexed lateral position of the pulmonary valve was utilized as a surrogate parameter for right ventricle localization.

RESULTS

In patients with PE, the heart's lateralization significantly correlated with the severity of pectus excavatum (p ≤ 0.001). When modifying HI and CI for the individual's pulmonary valve position, those indices are present with greater sensitivity and specificity regarding the maximum oxygen-pulse as a pathophysiological correlate of reduced cardiac function (χ² 10.986 and 15.862, respectively).

CONCLUSION

The indexed lateral deviation of the pulmonary valve seems to be a valuable cofactor for HI and CI, allowing for an improved description of cardiopulmonary impairment in PE patients.

Hemoglobin A1c in type 2 diabetes mellitus patients with preserved ejection fraction is an independent predictor of left ventricular myocardial deformation and tissue abnormalities

BACKGROUND

Early detection of subclinical myocardial dysfunction in patients with type 2 diabetes mellitus (T2DM) is essential for preventing heart failure. This study aims to search for predictors of left ventricular (LV) myocardial deformation and tissue abnormalities in T2DM patients with preserved ejection fraction by using CMR T1 mapping and feature tracking.

METHODS

70 patients and 44 sex- and age-matched controls (Cs) were recruited and underwent CMR examination to obtain LV myocardial extracellular volume fraction (ECV) and global longitudinal strain (GLS). The patients were subdivided into three groups, including 19 normotensive T2DM patients (G1), 19 hypertensive T2DM patients (G2) and 32 hypertensive patients (HT). The baseline biochemical indices were collected before CMR examination.

RESULTS

LV ECV in T2DM patients was significantly higher than that in Cs (30.75 ± 3.65% vs. 26.33 ± 2.81%; p < 0.05). LV GLS in T2DM patients reduced compared with that in Cs (-16.51 ± 2.53% vs. -19.66 ± 3.21%, p < 0.001). In the subgroup analysis, ECV in G2 increased compared with that in G1 (31.92 ± 3.05% vs. 29.59 ± 3.90%, p = 0.032) and that in HT, too (31.92 ± 3.05% vs. 29.22 ± 6.58%, p = 0.042). GLS in G2 significantly reduced compared with that in G1 (-15.75 ± 2.29% vs. -17.27 ± 2.57%, p < 0.05) and in HT, too (-15.75 ± 2.29% vs. -17.54 ± 3.097%, p < 0.05). In T2DM group, including both G1 and G2, hemoglobin A1c (HbA1c) can independently forecast the increase in ECV (β = 0.274, p = 0.001) and decrease in GLS (β = 0.383, p = 0.018).

CONCLUSIONS

T2DM patients with preserved ejection fraction show increased ECV but deteriorated GLS, which may be exacerbated by hypertension of these patients. Hemoglobin A1c is an index that can independently predict T2DM patients' LV myocardial deformation and tissue abnormalities.

The influence of chest wall conformation on myocardial strain parameters in a cohort of mitral valve prolapse patients with and without mitral annular disjunction

PURPOSE

To evaluate the possible influence of chest wall conformation on myocardial strain parameters in a cohort of mitral valve prolapse (MVP) patients with and without mitral annular disjunction (MAD).

METHODS

All consecutive middle-aged patients with MVP referred to our Outpatient Cardiology Clinic for performing two-dimensional (2D) transthoracic echocardiography (TTE) as part of work up for primary cardiovascular prevention between March 2018 and May 2022, were included into the study. All patients underwent clinic visit, physical examination, modified Haller index (MHI) assessment (the ratio of chest transverse diameter over the distance between sternum and spine) and conventional 2D-TTE implemented with speckle tracking analysis of left ventricular (LV) global longitudinal strain (GLS) and global circumferential strain (GCS). Independent predictors of MAD presence on 2D-TTE were assessed.

RESULTS

A total of 93 MVP patients (54.2 ± 16.4 yrs, 50.5% females) were prospectively analyzed. On 2D-TTE, 34.4% of MVP patients had MAD (7.3 ± 2.0 mm), whereas 65.6% did not. Compared to patients without MAD, those with MAD had: 1) significantly shorter antero-posterior (A-P) thoracic diameter (13.5 ± 1.2 vs 14.8 ± 1.3 cm, p < 0.001); 2) significantly smaller cardiac chambers dimensions; 3) significantly increased prevalence of classic MVP (84.3 vs 44.3%, p < 0.001); 4) significantly impaired LV-GLS (-17.2 ± 1.4 vs -19.4 ± 3.0%, p < 0.001) and LV-GCS (-16.3 ± 4.1 vs -20.4 ± 4.9, p < 0.001), despite similar LV ejection fraction (63.7 ± 4.2 vs 63.0 ± 3.9%, p = 0.42). A-P thoracic diameter (OR 0.25, 95%CI 0.10-0.82), classic MVP (OR 3.90, 95%CI 1.32-11.5) and mitral annular end-systolic A-P diameter (OR 2.76, 95%CI 1.54-4.92) were the main independent predictors of MAD. An A-P thoracic diameter ≤ 13.5 cm had 59% sensitivity and 84% specificity for predicting MAD presence (AUC = 0.81). In addition, MAD distance was strongly influenced by A-P thoracic diameter (r = - 0.96) and MHI (r = 0.87), but not by L-L thoracic diameter (r = 0.23). Finally, a strong inverse correlation between MHI and both LV-GLS and LV-GCS was demonstrated in MAD patients (r = - 0.94 and - 0.92, respectively), but not in those without (r = - 0.51 and - 0.50, respectively).

CONCLUSIONS

A narrow A-P thoracic diameter is strongly associated with MAD presence and is a major determinant of the impairment in myocardial strain parameters in MAD patients, in both longitudinal and circumferential directions.

Usefulness of strain cardiac magnetic resonance for the exposure of mild left ventricular systolic abnormalities in pectus excavatum

BACKGROUND

Systolic dysfunction in pectus excavatum (PEX) is usually very subtle and mainly focused on the right ventricle (RV), leading to normal or unremarkable cardiac imaging findings unless involving exercise stress.

OBJECTIVES

We evaluated systolic function in PEX using longitudinal strain cardiac magnetic resonance (CMR), a validated parameter for the assessment of the systolic deformation of subendocardial fibers.

METHODS

This prospective registry comprised consecutive patients with PEX who were referred to CMR to define treatment strategies or to establish surgical candidacy. We also included a control group of 15 healthy volunteers without chest wall abnormalities. Using dedicated software, we evaluated the endocardial global longitudinal strain (GLS) of both ventricles and the endocardial global circumferential strain (GCS) of the left ventricle (LV).

RESULTS

A total of 50 patients with PEX comprised the study population, with a mean age of 19.9 ± 8.0 years. The right ventricular ejection fraction (RVEF) of patients with PEX was significantly lower compared to the control group both at end-expiration (59.5 ± 6.8 vs. 64.7 ± 4.7%, p = 0.008) and end-inspiration (56.7 ± 7.2%, vs. 62.7 ± 4.4, p = 0.004); as well as the pulmonary stroke distance (12.6 ± 2.5, vs. 15.0 ± 2.0 cm, p = 0.001). The LV volumetric analysis revealed no differences between PEX and the control group (p > 0.05 for all) regardless of the respiratory cycle, with a mean expiratory LV ejection fraction (LVEF) of 61.4 ± 6.0%. In contrast, the GLS of the LV was significantly lower in PEX compared to controls (-21.2 ± 3.2 vs. -23.7 ± 3.0%, p = 0.010), whereas GCS was similar either at expiration (-28.5 ± 4.0%, vs. -29.5 ± 2.8, p = 0.38) or inspiration (-29.3 ± 4.1%, vs.-28.9 ± 2.3, p = 0.73).

CONCLUSIONS

In this study, we demonstrated that longitudinal strain analysis might enable the detection of very subtle left ventricular systolic function abnormalities in patients with PEX, that are commonly overlooked using the conventional assessment.

LEVEL OF EVIDENCE

II.

Intraoperative cardiac function assessment by transesophageal echocardiography versus FloTrac/Vigileo™ system during pectus excavatum surgical repair

BACKGROUND

Pectus excavatum (PE), a congenital deformity of the chest wall, can lead to cardiac compression and related symptoms. PE surgical repair can improve cardiac function. Intraoperative transesophageal echocardiography (TEE) has been successfully employed to assess intraoperative hemodynamic variations in patients undergoing PE repair. FloTrac/Vigileo™ system (Edwards Life-sciences Irvine, CA) (FT/V) is a minimally invasive cardiac output monitoring system. This retrospective study aimed to assess hemodynamic changes in surgical repair of PE using FT/V and concordance with parameters measured by TEE.

RESULTS

N=19 patients submitted to PE repair via Ravitch or Nuss technique were enrolled. Intraoperative cardiac assessments simultaneously obtained via TEE and FT/V system were investigated. The agreement between TEE-derived cardiac output (CO-TEE) and FT/V system parameter (COAP) was evaluated. The relationship between COTEE and COAP was analyzed for all data using linear regression analysis. A significant correlation between COAP and COTEE values (R = 0.65, p < 0.001) was found. Bland-Altman analysis of COAP and COTEE showed a bias of 0.13 L/min and a limit of agreement of - 2.33 to 2.58 L/min, with a percentage error of 48%. Intraoperative measurements by TEE and FT/V both showed a significant increase in CO after surgical correction of PE (p < 0.005).

CONCLUSIONS

FT/V system compared to TEE in hemodynamic monitoring during PE surgery yielded clinically unacceptable results due to a high percentage error. After surgical correction of PE, CO, measured by TEE and FT/V, significantly improved.

Does chest wall conformation influence myocardial strain parameters in infants with pectus excavatum?

PURPOSE

To investigate the possible influence of chest wall conformation on myocardial strain parameters in a consecutive population of infants with pectus excavatum (PE), noninvasively assessed by modified Haller index (MHI).

METHODS

Sixteen consecutive PE infants (MHI >2.5) and 44 infants with normal chest shape (MHI ≤2.5) entered in this prospective case-control study. All infants underwent evaluation by neonatologist, transthoracic echocardiography implemented with two-dimensional speckle tracking echocardiography (2D-STE) analysis of both ventricles and MHI assessment (ratio of chest transverse diameter over the distance between sternum and spine), at two time points: within 3 days and at about 40 days of life.

RESULTS

At 2.1 ± 1 days of life, compared to controls (MHI = 2.01 ± 0.2), PE infants (MHI = 2.76 ± 0.2) were diagnosed with significantly smaller cardiac chambers dimensions. Biventricular contractile function and hemodynamics were similar in both groups of infants. Left ventricular (LV) global longitudinal strain (GLS) (-16.0 ± 2.8 vs. -21.7 ± 2.2%), LV-global circumferential strain (GCS) (-16.3 ± 2.7 vs. -24.0 ± 5.2%), LV-global radial strain (GRS) (24.2 ± 3.0 vs. 31.5 ± 6.3%), and right ventricular free wall longitudinal strain (RVFWLS) (-16.0 ± 3.2 vs. -22.3 ± 4.4%) were significantly reduced in PE infants versus controls (all p < 0.001). A strong inverse correlation between MHI and the following parameters: LV-GLS (r = -0.92), LV-GCS (r = -0.88), LV-GRS (r = -0.87), and RVFWLS (r = -0.88), was demonstrated in PE infants, but not in controls, in perinatal period (all p < 0.001). Analogous results were obtained at 36.8 ± 5.2 days after birth.

CONCLUSIONS

Abnormal chest anatomy progressively impairs myocardial strain parameters in PE infants. This impairment might reflect intraventricular dyssynchrony due to compressive phenomena rather than intrinsic myocardial dysfunction.

Cardiovascular MRI assessment of pectus excavatum in pediatric patients and postoperative simulation using vacuum bell

BACKGROUND

The sternal lift by Vacuum Bell (VB) is effective, as largely demonstrated by its intraoperative use during surgical procedure to elevate the sternum during the Nuss procedure routinely. Indeed, the thoracic remodelling during VB application is comparable to post-surgical scenario, and suitable to compare cardiovascular parameters of the two different thoracic configurations immediately.

OBJECTIVE

We would quantify and correlate preoperative parameters which determine the severity of the pectus excavatum (PE), and the cardiovascular effects at the baseline. Than we would assess the cardiovascular changes during VB positioning, mimicking the immediate, temporary effect of Pectus-correction.

MATERIALS AND METHODS

We included 26 consecutive patients (mean age is 13,3 +/- 2,2 years) symptomatic and non, with a previous clinical diagnosis of PE. CMR was performed before and during application of VB, using the same imaging protocol. In both conditions, we measured thoracic indexes, and cardiac function as well as flow through main vessels.

RESULTS

Mean expiratory Haller Index (HI) was 5,4 (+/-1,4 SD; normal <3). During VB application, all patients showed improvement in the main morphologic parameters of the thorax (mean expiratory HI = 4,7 (+/-1,6 SD, delta -13%, P = 0,01). During VB application, a minimal but not significant increase of Right Ventricle End Diastolic Volume (RVEDVi) (delta +4,6%, P = 0,12), and Right Ventricle Ejection Fraction (RVEF) (delta +1,2%, P = 0,2) was observed.

CONCLUSION

In adolescents affected by PE, cardiacMRI (CMR) demonstrates normal values of biventricular volume and systolic function. During VB application, beside significative improvements in chest wall anatomy, CMR shows a minimal positive variation in right ventricle volume and function. A minority of patients showed some degree of diastolic dysfunction at baseline, unchanged after VB application, with possible correlation between valve inflow and sternal impingement.

Malignant mesothelioma associated with localized myocardial fibrosis: a case report

Left ventricular dysfunction is a common reason for patients' referral to cardiology departments for examination. Cardiac involvement is one of the possible yet rare presentations of malignant mesothelioma. We present a case of a patient in whom a routine cardiac examination and imaging revealed malignant mesothelioma. We discuss a possible association between a malignant tumor and myocardial scarring and how the oncologic treatment is influenced by concomitant heart failure. This article aims to raise awareness of the importance of multidisciplinary cooperation and thinking beyond the daily routine of our specialty to ensure the quality care of our patients. It also forced us to think about the possible causes of the association between malignant mesothelioma and myocardial fibrosis.

Impact of chest wall deformity on cardiac function by CMR and feature-tracking strain analysis in paediatric patients with Marfan syndrome

Objectives

To evaluate systolic cardiac dysfunction in paediatric MFS patients with chest wall deformity using cardiac magnetic resonance (CMR) imaging and feature-tracking strain analysis.

Methods

Forty paediatric MFS patients (16 ± 3 years, range 8−22 years) and 20 age-matched healthy controls (16 ± 4 years, range 11−24 years) were evaluated retrospectively. Biventricular function and volumes were determined using cine sequences. Feature-tracking CMR was used to assess global systolic longitudinal (GLS), circumferential (GCS) and radial strain (GRS). A dedicated balanced turbo field echo sequence was used to quantify chest wall deformity by measuring the Haller index (HI).

Results

LV volumes and ejection fraction (EF) were similar in MFS patients and controls. There was a trend for lower right ventricular (RV) volume (75 ± 17 vs. 81 ± 10 ml/m², p = 0.08), RV stroke volume (41 ± 12 vs. 50 ± 5 ml/m², p < 0.001) and RVEF (55 ± 10 vs. 62 ± 6%, p < 0.01) in MFS patients. A subgroup of MFS patients had an increased HI compared to controls (4.6 ± 1.7 vs. 2.6 ± 0.3, p < 0.001). They demonstrated a reduced RVEF compared to MFS patients without chest wall deformity (50 ± 11% vs. 58 ± 8%, p = 0.01) and controls (p < 0.001). LV GLS was attenuated when HI ≥ 3.25 (- 16 ± 2 vs. - 18 ± 3%, p = 0.03), but not GCS and GRS. LV GLS (p < 0.01) and GCS (p < 0.0001) were attenuated in MFS patients compared to controls, but not GRS (p = 0.31). RV GLS was attenuated in MFS patients compared to controls (- 21 ± 3 vs. - 23 ± 3%, p < 0.05).

Conclusion

Chest wall deformity in paediatric MFS patients is associated with reduced RV volume, ejection fraction and GLS. Feature-tracking CMR also indicates impairment of systolic LV function in paediatric MFS patients.

Key Points

• Paediatric Marfan patients demonstrate reduced RV volume and ejection fraction compared to healthy controls.

• A concordant attenuation in RV global longitudinal strain was observed in Marfan patients, while the RV global circumferential strain was increased, indicating a possible compensatory mechanism.

• Subgroup analyses demonstrated alterations in RV ejection fraction and RV/LV global strain parameters, indicating a possible association of severe chest wall deformity with biventricular dysfunction in paediatric Marfan patients.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00330-020-07616-9.

False-positive electrocardiographic changes during exercise test in a patient with pectus excavatum

Exercise-induced ST-segment changes simulating myocardial ischemia have been described in otherwise normal subjects during hyperventilation. We present the case of a 60-year-old man with pectus excavatum showing significant exercise-induced "pseudo-ischaemic" ST-segment changes with neither coronary artery disease nor anxiety-induced hyperventilation. We found no report of the possible causative role of a narrow antero-posterior chest diameter in inducing "pseudo-ischaemic" ST-segment changes during exercise stress test in the literature.

Influence of chest conformation on myocardial strain parameters in healthy subjects with mitral valve prolapse

Chest shape might affect myocardial strain parameters. However, the relationship between myocardial strain parameters and chest conformation has not been previously investigated in subjects with mitral valve prolapse (MVP). Between April 2019 and May 2020, 60 healthy subjects (50.1 ± 8.6 year/old, 46.6% females) with MVP and mild-to-moderate mitral regurgitation, and 60 controls matched by age, sex, and cardiovascular risk factors were consecutively studied. Participants underwent modified Haller index (MHI) assessment (ratio of chest transverse diameter over the distance between sternum and spine), and transthoracic echocardiography implemented with 2D-speckle tracking analysis. MHI was significantly greater in MVP group than controls (2.6 ± 0.35 vs 2.1 ± 0.23, p < 0.0001). Left ventricular (LV) ejection fraction was similar in MVP and controls (63.5 ± 3.7% vs 64.3 ± 3.9%, p = 0.25). LV regional and global longitudinal (GLS), circumferential (GCS) and radial strain (GRS) parameters and LV peak twist were all significantly lower in MVP compared to controls (all p < 0.0001). MVP subjects with a tight chest (MHI > 2.5, n = 30), and those with MHI ≤ 2.5 (n = 30) were then separately analyzed. A significant impairment in myocardial strain parameters and LV peak twist was documented in MVP subjects with MHI > 2.5, but not in those with MHI ≤ 2.5. MHI showed a strong inverse correlation with LV-GLS (r = - 0.85), GCS (r = - 0.84), GRS (r = - 0.84) and LV peak twist (r = - 0.94). In MVP subjects, impairment of myocardial strain parameters is not due to intrinsic reduction of cardiac contractility function, but it appears to be related to the degree of chest deformity.

Research progress in the effects of pectus excavatum on cardiac functions

Background

Pectus excavatum, the most common chest wall deformity in children, accounts for nearly 90% of congenital malformations of chest wall. Initially, both parents and doctors paid more attention to the influence of this deformity on patient appearance and psychology. Following deeper studies of pectus excavatum, researchers found that it also affected cardiac functions. The purpose of this review aims to present recent research progress in the effects of pectus excavatum on cardiac functions.

Data sources

Based on aspects of CT, ultrasound cardiography (UCG) and MRI, all the recent literatures on the influence of pectus excavatum on cardiac function were searched and reviewed.

Results

Moderate and severe pectus excavatum did have a negative effect on cardiac function. Cardiac rotation angle, cardiac compression index, right atrial and tricuspid annulus size, septal motion and myocardial strain are relatively effective indexes to evaluate cardiac function.

Conclusions

Pectus excavatum did have a negative effect on cardiac function; so surgeons should actively diagnose and treat such patients in clinical work. However, further research is needed on to explore the measures and indicators that can reflect the changes of cardiac function in patients objectively, accurately, effectively and timely.

Reduced Myocardial Strain Parameters in Subjects With Pectus Excavatum: Impaired Myocardial Function or Methodological Limitations Due to Chest Deformity?

Pectus excavatum (PE) may cause symptoms and alter cardiopulmonary function. Left ventricular (LV) and right ventricular (RV) function have been reported to be impaired in PE subjects. However, this issue has not been systematically investigated with respect to the degree of chest wall abnormality. We aimed to evaluate the influence of severity of chest shape abnormality on myocardial strain parameters in PE subjects. We studied 30 healthy subjects (55.8 ± 14.0 year/old, 18 males) with PE, assessed by the ratio of chest transverse diameter over the distance between sternum and spine (modified Haller index, MHI, >2.5), and 30 controls (MHI ≤2.5) matched by age, sex, and cardiovascular risk factors. Participants underwent 2-dimensional (2D) transthoracic echocardiography implemented with 2D-speckle tracking echocardiography. Right-heart and left-heart chamber dimensions, and stroke volume, were significantly reduced in PE subjects (all P< 0.0001). While LV ejection fraction, E/A, and E/e', did not significantly differ between the 2 groups, all LV and RV strain and strain rate parameters were severely reduced in subjects with PE (P < 0.0001). Importantly, in PE subjects, but not in controls, LV global longitudinal strain, LV global circumferential strain, LV global radial strain, and RV free wall systolic strain, were all linearly correlated to MHI (all P < 0.0001). In healthy subjects with PE, abnormal chest anatomy progressively impairs myocardial strain. However, this impairment is not due to subclinical myocardial dysfunction; it might reflect intraventricular dyssynchrony due to compressive phenomena, or technical limitations of strain methodology, due to chest wall abnormality.

Regional right ventricular function in rats: a novel magnetic resonance imaging method for measurement of right ventricular strain

The function of the right ventricle (RV) is linked to clinical outcome in many cardiovascular diseases, but its role in experimental heart failure remains largely unexplored due to difficulties in measuring RV function in vivo. We aimed to advance RV imaging by establishing phase-contrast MRI (PC-MRI) as a robust method for measuring RV function in rodents. A total of 46 Wistar-Hannover rats with left ventricular (LV) myocardial infarction and 10 control rats (sham) were examined 6 wk after surgery. Using a 9.4-T preclinical MRI system, we utilized PC-MRI to measure strain/strain rate in the RV free wall under isoflurane anesthesia. Cine MRI was used to measure RV volumes. LV end-diastolic pressure (LVEDP) was measured and used to identify pulmonary congestion. The infarct rats were divided into two groups: those with signs of pulmonary congestion (PC), with LVEDP ≥ 15 mmHg ( n = 26) and those without signs of pulmonary congestion (NPC), with LVEDP < 15 mmHg ( n = 20). The NPC rats exhibited preserved RV strains/strain rates, whereas the PC rats exhibited reduced strains/strain rates (26–48% lower than sham). Of the strain parameters, longitudinal strain and strain rate exhibited the highest correlations to LVEDP and lung weight (rho = 0.65–0.72, P < 0.001). Basal longitudinal strain was most closely associated with signs of pulmonary congestion and indexes of RV remodeling. Longitudinal RV strain had higher area under the curve than ejection fraction for detecting subtle RV dysfunction (area under the curve = 0.85 vs. 0.67). In conclusion, we show for the first time that global and regional RV myocardial strain can be measured robustly in rodents. Reduced RV strain was closely associated with indexes of pulmonary congestion and molecular markers of RV remodeling.

NEW & NOTEWORTHY Global and regional right ventricular myocardial strain can be measured with high reproducibility and low interobserver variability in rodents using tissue phase mapping MRI. Reduced right ventricular strain was associated with indexes of pulmonary congestion and molecular markers of right ventricular remodeling. Regional strain in the basal myocardium was considerably higher than in the apical myocardium.

Quantification of regional right ventricular strain in healthy rats using 3D spiral cine dense MRI

Statistical data from clinical studies suggests that right ventricular (RV) circumferential strain (Ecc) and longitudinal strain (Ell) are significant biomarkers for many cardiovascular diseases. However, a detailed and regional characterization of these strains in the RV is very limited. In the current study, RV images were obtained with 3D spiral cine DENSE MRI in healthy rats. An algorithm for surface growing was proposed in order to fit irregular topology. Specifically, a new custom plugin for the DENSEanalysis program, called 3D DENSE Plugin for Crescent Organ, was developed for surface reconstruction and precise segmentation of organs with sharp curvature, such as the murine RV. The RV free wall (RVFW) was divided into three longitudinal thirds (i.e., basal, middle, and apical) with each one partitioned into circumferential fourths (i.e., anterior, anteriorlateral, inferiorlateral and inferior). Peak systolic strains were quantified for each segment and comparisons were performed statistically. The inclusion of a new plugin was able to generate global values for Ecc and Ell that are in good agreement with previous findings using MRI. Despite no regional variation found in the peak Ecc, the peak Ell exhibited regional variation at the anterior side of the RV, which is potentially due to differences in biventricular torsion at the RV insertion point and fiber architecture. These results provide fundamental insights into the regional contractile function of the RV in healthy rat and could act as a normative baseline for future studies on regional changes induced by disease or treatment.

Effect of internal fixation of the sternum using bioabsorbable pins in small children

OBJECTIVES

A sternal pin can be used to internally fix the reapproximated sternum after midline sternotomy. This paper will evaluate the effectiveness of using a sternal pin in small children by means of a computer tomography scan.

METHODS

Propensity score matching was performed for patients undergoing a first-time median sternotomy from April 2012 to December 2014 with a follow-up computer tomography scan after 6 months. Seventeen matched patients were selected for both the control and the sternal pin groups. The angle of the sternal reflection at the joint surface was measured by computer tomography scan. In addition, the Haller index was measured at each thoracic vertebral level.

RESULTS

The angle of the sternal reflection was more variable in the control group compared with the sternal pin group: the standard deviation was 31.6° for the control group and 10.2° for the sternal pin group (P value = .0009). Seven out of 17 patients in the control group had a negative angle (excavated sternum) compared with 1 out of 17 in the sternal pin group (P = .0391). In the other patients, the angle was 23.9° ± 3.6° in the control group and 10.1 ± 2.8 in the sternal pin group (P = .0061). The Haller index was also more variable in the control group, and it was significantly different from the sternal pin group at the ninth vertebral level (P = .0409).

CONCLUSIONS

The study demonstrated that the use of a sternal pin was associated with decreased variation in the sternal angles and decreased incidence and severity of sternal protrusion and excavation in small children.

Cardiac magnetic resonance feature tracking for quantifying right ventricular deformation in type 2 diabetes mellitus patients

To determine the feasibility of deformation analysis in the right ventricle (RV) using cardiovascular magnetic resonance myocardial feature tracking (CMR-FT) in type 2 diabetes mellitus (T2DM) patients. We enrolled 104 T2DM patients, including 14 with impaired right ventricular ejection fraction (RVEF) and 90 with preserved RVEF, and 26 healthy controls in this prospective study. CMR was used to determine RV feature-tracking parameters. RV strain parameters were compared among the controls, patients with preserved and reduced RVEF. Binary logistic regression was used to predict RV dysfunction. Receiver operating characteristic analysis was used to assess the diagnostic accuracy. The agreement was tested by Bland-Altman analysis. Compared with controls, longitudinal and circumferential global peak strain (PS) and PS at mid-ventricular, apical slices were significantly decreased in T2DM patients with or without reduced RVEF (p < 0.05). Within the T2DM patients, the global longitudinal PS (GLPS) and the longitudinal PS at mid-ventricular segments were significantly reduced in the reduced RVEF group than in preserved RVEF groups (p < 0.05). GLPS was an independent predictor of RV dysfunction (odds ratio: 1.246, 95% CI: 1.037-1.496; p = 0.019). The GLPS demonstrated greater diagnostic accuracy (area under curve: 0.716) to predict RV dysfunction. On Bland-Altman analysis, global circumferential PS and GLPS had the best intra- and inter-observer agreement, respectively. In T2DM patients, CMR-FT could quantify RV deformation and identify subclinical RV dysfunction in those with normal RVEF. Further, RV strain parameters are potential predictors for RV dysfunction in T2DM patients.