Non-invasive determination by cardiovascular magnetic resonance of right ventricular-vascular coupling in children and adolescents with pulmonary hypertension

Background

Pediatric pulmonary hypertension (PH) remains a disease with high morbidity and mortality in children. Understanding ventricular-vascular coupling, a measure of how well matched the ventricular and vascular function are, may elucidate pathway leading to right heart failure. Ventricular vascular coupling ratio (VVCR), comprised of effective elastance (E_a, index of arterial load) and right ventricular maximal end-systolic elastance (E_es, index of contractility), is conventionally determined by catheterization. Here, we apply a non-invasive approach to determining VVCR in pediatric subjects with PH.

Methods

This retrospective study included PH subjects who had a cardiovascular magnetic resonance (CMR) study within 14 days of cardiac catheterization. PH was defined as mean pulmonary artery pressure (mPAP) ≥ 25 mmHg on prior or current catheterization. A non-invasive measure of VVCR was derived from CMR-only (VVCR_m) and compared to VVCR estimated by catheterization-derived single beat estimation (VVCR_s). Indexed pulmonary vascular resistance (PVRi) and pulmonary vascular reactivity were determined during the catheterization procedure. Pearson correlation coefficients were calculated between PVRi and VVCR_m. Receiver operating characteristic (ROC) curve analysis determined the diagnostic value of VVCR_m in predicting vascular reactivity.

Results

Seventeen subjects (3 months-23 years; mean 11.3 ± 7.4 years) were identified between January 2009-August 2013 for inclusion with equal gender distributions. Mean mPAP was 35 mmHg ± 15 and PVRi was 8.5 Woods unit x m2 ± 7.8. VVCR_m (range 0.43–2.82) increased with increasing severity as defined by PVRi (p < 0.001), and was highly correlated with PVRi (r = 0.92, 95 % CI 0.79–0.97, p < 0.0001). Regression of VVCR_m and PVRi demonstrated differing lines when separated by reactivity. VVCR_m was significantly correlated with VVCR_s (r = 0.79, CI 0.48–0.99, p <0.0001). ROC curve analysis showed high accuracy of VVCR_m in determining vascular reactivity (VVCR = 0.85 had a sensitivity of 100 % and a specificity of 80 %) with an area under the curve of 0.89 (p = 0.008).

Conclusion

Measurement of VVCR_m in pediatrics is feasible. Pulmonary vascular non-reactivity may be contribute to ventricular-vascular decoupling in severe PH. Therapeutic intervention to maintain a low vascular afterload in reactive patients may preserve right ventricular functional reserve and delay the onset of RV-PA decoupling. Use of VVCR_m may have significant prognostic implication.     

Right ventricular adaptation to pulmonary pressure load in patients with chronic thromboembolic pulmonary hypertension before and after successful pulmonary endarterectomy - a cardiovascular magnetic resonance study

Background

The aim of the study was to characterize RV adaptation to varying loading conditions in patients with chronic thromboembolic hypertension (CTEPH) before and after pulmonary endarterectomy (PEA). Nearly 4% of patients with pulmonary embolism develop CTEPH. PEA offers a cure with excellent outcome. By use of cardiovascular magnetic resonance (CMR) combined with hemodynamic measurements pulmonary arterial elastance (E_{a-pulm_i}), end-systolic right ventricular elastance (E_{es-RV_i}) and ventriculo-arterial coupling (E_{a-pulm_i}/E_{es-RV_i}) can be studied before and after PEA.

Methods

Sixty-five patients (mean age 41 ± 12 years, 28 female) underwent CMR pre- and post-PEA. Ejection fraction (EF), end-diastolic (EDV_i), end-systolic (ESV_i), and stroke (SV_i) volumes were indexed for body surface area. E_{a-pulm_i} was calculated as pulmonary artery mean pressure (mPAP)/SV_i, and E_{es-RV_i} as mPAP/ESV_i.

Results

mPAP decreased from 47 ± 12 to 25 ± 9 mmHg, p =0.0001. E_{a-pulm_i} was increased before PEA and normalized afterwards (2.8 ± 2.1 vs. 0.85 ± 0.4 mmHg/ml/m², p =0.0001). E_{es-RV_i} was depressed before and after PEA (0.72 ± 0.27 vs. 0.66 ± 0.3 mmHg/ml/m², p =0.13). EF improved from 25 ± 12% to 46 ± 10%, p =0.0001, because ventriculo-arterial coupling was restored (4.2 ± 3 vs. 1.4 ± 0.6, p =0.0001). EDV_i and ESVi mproved significantly (EDV_i 92 ± 32 to 72 ± 23 ml, p =0.0001; ESV_i 69 ± 31 to 41 ± 18 ml, p =0.0001).

Conclusion

RV function is largely determined by afterload and returns to normal once afterload is normalized. This is paralleled by a significant improvement of CMR indices of right ventricular remodelling.     

Wall shear stress measured by phase contrast cardiovascular magnetic resonance in children and adolescents with pulmonary arterial hypertension

Background

Pulmonary arterial hypertension (PAH) is a devastating disease with significant morbidity and mortality. At the macroscopic level, disease progression is observed as a complex interplay between mean pulmonary artery pressure, pulmonary vascular resistance, pulmonary vascular stiffness, arterial size, and flow. Wall shear stress (WSS) is known to mediate or be dependent on a number of these factors. Given that WSS is known to promote architectural vessel remodeling, it is imperative that the changes of this factor be quantified in the presence of PAH.

Methods

In this study, we analyzed phase contrast imaging of the right pulmonary artery derived from cardiovascular magnetic resonance to quantify the local, temporal and circumferentially averaged WSS of a PAH population and a pediatric control population. In addition, information about flow and relative area change were derived.

Results

Although the normotensive and PAH shear waveform exhibited a WSS profile which is uniform in magnitude and direction along the vessel circumference at systole, time-averaged WSS (2.2 ± 1.6 vs. 6.6 ± 3.4 dynes/cm², P = 0.018) and systolic WSS (8.2 ± 5.0 v. 20.0 ± 9.1 dynes/cm², P = 0.018) was significantly depressed in the PAH population as compared to the controls. BSA-indexed PA diameter was significantly larger in the PAH population (1.5 ± 0.4 vs. 0.7 ± 0.1 cm/m², P = 0.003).

Conclusions

In the presence of preserved flow rates through a large PAH pulmonary artery, WSS is significantly decreased. This may have implications for proximal pulmonary artery remodeling and cellular function in the progression of PAH.     

心脏MRI在射血分数保留型心力衰竭中的应用进展

近年来，以舒张功能障碍（DD）为主要特征的射血分数保留型心力衰竭（HFpEF）逐渐引起临床重视，作为高空间分辨率、高信噪比的非侵入性"一站式"检查方式，心脏MRI（CMR）对评估左心室舒张功能具有重要价值。本文就CMR及其早期识别和评估HFpEF患者DD的应用进展进行综述。     

Diagnostic accuracy of cardiovascular magnetic resonance imaging of right ventricular morphology and function in the assessment of suspected pulmonary hypertension results from the ASPIRE registry

Background

Cardiovascular Magnetic Resonance (CMR) imaging is accurate and reproducible for the assessment of right ventricular (RV) morphology and function. However, the diagnostic accuracy of CMR derived RV measurements for the detection of pulmonary hypertension (PH) in the assessment of patients with suspected PH in the clinic setting is not well described.

Methods

We retrospectively studied 233 consecutive treatment naïve patients with suspected PH including 39 patients with no PH who underwent CMR and right heart catheterisation (RHC) within 48hours. The diagnostic accuracy of multiple CMR measurements for the detection of mPAP ≥ 25 mmHg was assessed using Fisher’s exact test and receiver operating characteristic (ROC) analysis.

Results

Ventricular mass index (VMI) was the CMR measurement with the strongest correlation with mPAP (r = 0.78) and the highest diagnostic accuracy for the detection of PH (area under the ROC curve of 0.91) compared to an ROC of 0.88 for echocardiography calculated mPAP. Late gadolinium enhancement, VMI ≥ 0.4, retrograde flow ≥ 0.3 L/min/m² and PA relative area change ≤ 15% predicted the presence of PH with a high degree of diagnostic certainty with a positive predictive value of 98%, 97%, 95% and 94% respectively. No single CMR parameter could confidently exclude the presence of PH.

Conclusion

CMR is a useful alternative to echocardiography in the evaluation of suspected PH. This study supports a role for the routine measurement of ventricular mass index, late gadolinium enhancement and the use of phase contrast imaging in addition to right heart functional indices in patients undergoing diagnostic CMR evaluation for suspected pulmonary hypertension.     

Prognostic value of pulmonary vein size in prediction of atrial fibrillation recurrence after pulmonary vein isolation: a cardiovascular magnetic resonance study

Background

The relationship between pulmonary vein (PV) anatomy and successful catheter ablation of atrial fibrillation (AF) is poorly understood

Methods

First-pass contrast enhanced PV magnetic resonance angiography was performed in 71 consecutive patients prior to PV isolation. PV diameter and cross-sectional area (CSA) were measured prior to PV isolation. Any symptomatic or asymptomatic AF >10s was considered a recurrence. Early recurrence was defined as recurrent AF ≤30 days after PV isolation, while late recurrence of AF was defined as recurrent AF >30 days after.

Results

At 1 year, 57 % had any recurrence of AF while 41 % had late recurrence of AF. Study subjects with one or more PV diameter in the top 10^th percentile had trend toward more early recurrent AF (HR 1.99, p = 0.053). Study subjects with one or more PV CSA in the top 10^th percentile had more late recurrent AF (HR 2.25, p = 0.039) and a trend toward more early recurrent AF (HR 1.94, p = 0.064). With multivariate analysis, PV size was not associated with early recurrent AF, but late recurrent AF was associated with one or more large PV, increased left atrial size, and non-paroxysmal AF. Study subjects with all three of these risk factors had a 100 % rate of late recurrent AF at 1 year, while those with none had a 7 % rate of late recurrent AF.

Conclusions

Larger PV size is independently associated with more late recurrent AF after PV isolation. Determination of PV size prior to PV isolation may predict procedural success.     

路径式护理在H型高血压合并射血分数保留的心力衰竭治疗中的应用

目的:探讨路径式护理在H型高血压合并射血分数保留的心力衰竭(hear t failure with preserved ejection fraction,HFPEF)治疗中的应用效果。方法:选取秦皇岛市第一医院心血管内科于2015年1月至2016年8月收治的100例H型高血压合并HFPEF患者为对照组,采用常规护理。选取2016年9月至2019年1月收治的100例H型高血压合并HFPEF患者为观察组,采用路径式护理。比较两组的健康知识掌握情况、血压、左房容积/体表面积(left atrial volume index,LAVI)等指标。结果:观察组的健康知识知晓率、去除高危因素重要性知晓率高于对照组,差异有统计学意义(P<0.05)。观察组干预后的收缩压、舒张压低于对照组,LAVI小于对照组,差异有统计学意义(P<0.05)。观察组干预后的同型半胱氨酸(homocysteine,Hcy)低于对照组,氨基末端脑肽钠前体(N-terminal pro-brain natriuretic peptide,NT-proBNP)低于对照组,差异有统计学意义(P<0.05)。结论:路径式护理能提高H型高血压合并HFPEF患者对自身疾病的认识,提高血压控制水平,改善左房泵血功能。     

Non-invasive assessment of cardiac function and pulmonary vascular resistance in an canine model of acute thromboembolic pulmonary hypertension using 4D flow cardiovascular magnetic resonance

Background

The purpose of this study was to quantify right (RV) and left (LV) ventricular function, pulmonary artery flow (Q_P), tricuspid valve regurgitation velocity (TRV), and aorta flow (Q_S) from a single 4D flow cardiovascular magnetic resonance (CMR) (time-resolved three-directionally motion encoded CMR) sequence in a canine model of acute thromboembolic pulmonary hypertension (PH).

Methods

Acute PH was induced in six female beagles by microbead injection into the right atrium. Pulmonary arterial (PAP) and pulmonary capillary wedge (PCWP) pressures and cardiac output (CO) were measured by right heart catheterization (RHC) at baseline and following induction of acute PH. Pulmonary vascular resistance (PVR_RHC) was calculated from RHC values of PAP, PCWP and CO (PVR_RHC = (PAP-PCWP)/CO). Cardiac magnetic resonance (CMR) was performed on a 3 T scanner at baseline and following induction of acute PH. RV and LV end-diastolic (EDV) and end-systolic (ESV) volumes were determined from both CINE balanced steady-state free precession (bSSFP) and 4D flow CMR magnitude images. Q_P, TRV, and Q_S were determined from manually placed cutplanes in the 4D flow CMR flow-sensitive images in the main (MPA), right (RPA), and left (LPA) pulmonary arteries, the tricuspid valve (TRV), and aorta respectively. MPA, RPA, and LPA flow was also measured using two-dimensional flow-sensitive (2D flow) CMR.

Results

Biases between 4D flow CMR and bSSFP were 0.8 mL and 1.6 mL for RV EDV and RV ESV, respectively, and 0.8 mL and 4 mL for LV EDV and LV ESV, respectively. Flow in the MPA, RPA, and LPA did not change after induction of acute PAH (p = 0.42-0.81). MPA, RPA, and LPA flow determined with 4D flow CMR was significantly lower than with 2D flow (p < 0.05). The correlation between Q_P/TRV and PVR_RHC was 0.95. The average Q_P/Q_S was 0.96 ± 0.11.

Conclusions

Using both magnitude and flow-sensitive data from a single 4D flow CMR acquisition permits simultaneous quantification of cardiac function and cardiopulmonary hemodynamic parameters important in the assessment of PH.     

Cardiovascular magnetic resonance in a pregnant patient with absent pulmonary valve syndrome

We present a 22 year old Moroccan woman with chronic severe pulmonary regurgitation, who becomes symptomatic in her fourth month of pregnancy. Cardiovascular magnetic resonance, during pregnancy, revealed a large pulmonary aneurysm and turbulent blood flow in the pulmonary trunk with severe pulmonary regurgitation. After gestation, the branch pulmonary arteries were assessed with magnetic resonance angiography and the severely dilated pulmonary arterial trunk and valve were replaced by a pulmonary homograft. We briefly review this rare syndrome, the management of pulmonary regurgitation during pregnancy and the role of CMR during pregnancy.     

Prevalence of scarred and dysfunctional myocardium in patients with heart failure of ischaemic origin: A cardiovascular magnetic resonance study

Background

Cardiovascular magnetic resonance (CMR) with late gadolinium enhancement (LGE) can provide unique data on the transmural extent of scar/viability. We assessed the prevalence of dysfunctional myocardium, including partial thickness scar, which could contribute to left ventricular contractile dysfunction in patients with heart failure and ischaemic heart disease who denied angina symptoms.

Methods

We invited patients with ischaemic heart disease and a left ventricular ejection fraction < 50% by echocardiography to have LGE CMR. Myocardial contractility and transmural extent of scar were assessed using a 17-segment model.

Results

The median age of the 193 patients enrolled was 70 (interquartile range: 63-76) years and 167 (87%) were men. Of 3281 myocardial segments assessed, 1759 (54%) were dysfunctional, of which 581 (33%) showed no scar, 623 (35%) had scar affecting ≤50% of wall thickness and 555 (32%) had scar affecting > 50% of wall thickness. Of 1522 segments with normal contractile function, only 98 (6%) had evidence of scar on CMR. Overall, 182 (94%) patients had ≥1 and 107 (55%) patients had ≥5 segments with contractile dysfunction that had no scar or ≤50% transmural scar suggesting viability.

Conclusions

In this cohort of patients with left ventricular systolic dysfunction and ischaemic heart disease, about half of all segments had contractile dysfunction but only one third of these had > 50% of the wall thickness affected by scar, suggesting that most dysfunctional segments could improve in response to an appropriate intervention.     

Cardiac output and cardiac index measured with cardiovascular magnetic resonance in healthy subjects,elite athletes and patients with congestive heart failure

Background

Cardiovascular Magnetic Resonance (CMR) enables non-invasive quantification of cardiac output (CO) and thereby cardiac index (CI, CO indexed to body surface area). The aim of this study was to establish if CI decreases with age and compare the values to CI for athletes and for patients with congestive heart failure (CHF).

Methods

CI was measured in 144 healthy volunteers (39 ± 16 years, range 21–81 years, 68 females), in 60 athletes (29 ± 6 years, 30 females) and in 157 CHF patients with ejection fraction (EF) below 40% (60 ± 13 years, 33 females). CI was calculated using aortic flow by velocity-encoded CMR and is presented as mean ± SD. Flow was validated in vitro using a flow phantom and in 25 subjects with aorta and pulmonary flow measurements.

Results

There was a slight decrease of CI with age in healthy subjects (8 ml/min/m² per year, r² = 0.07, p = 0.001). CI in males (3.2 ± 0.5 l/min/m²) and females (3.1 ± 0.4 l/min/m²) did not differ (p = 0.64). The mean ± SD of CI in healthy subjects in the age range of 20–29 was 3.3 ± 0.4 l/min/m², in 30–39 years 3.3 ± 0.5 l/min/m², in 40–49 years 3.1 ± 0.5 l/min/m², 50–59 years 3.0 ± 0.4 l/min/m² and >60 years 3.0 ± 0.4 l/min/m². There was no difference in CI between athletes and age-controlled healthy subjects but HR was lower and indexed SV higher in athletes. CI in CHF patients (2.3 ± 0.6 l/min/m²) was lower compared to the healthy population (p < 0.001). There was a weak correlation between CI and EF in CHF patients (r² = 0.07, p < 0.001) but CI did not differ between patients with NYHA-classes I-II compared to III-IV (n = 97, p = 0.16) or patients with or without hospitalization in the previous year (n = 100, p = 0.72). In vitro phantom validation showed low bias (−0.8 ± 19.8 ml/s) and in vivo validation in 25 subjects also showed low bias (0.26 ± 0.61 l/min, QP/QS 1.04 ± 0.09) between pulmonary and aortic flow.

Conclusions

CI decreases in healthy subjects with age but does not differ between males and females. We found no difference in CI between athletes and healthy subjects at rest but CI was lower in patients with congestive heart failure. The presented values can be used as reference values for flow velocity mapping CMR.     

左心室心肌应变参数预测初诊及未经治疗高血压患者射血分数保留性心力衰竭

目的 观察左心室心肌应变参数用于预测初诊及未经治疗高血压患者射血分数保留性心力衰竭(HFpEF)的价值。方法 纳入105例初诊或未经治疗原发性高血压伴HFpEF患者(HFpEF组)和131名健康志愿者(对照组),比较组间左心室结构、功能和心肌应变参数,包括舒张末期左心室内径(LVEDD)、收缩末期左心室内径(LVESD)、舒张末期室间隔厚度(IVSD)、舒张末期左心室后壁厚度(LVPWD)、左心室射血分数(LVEF)、二尖瓣口舒张早期血流峰值速度(E)、二尖瓣口舒张晚期血流峰值速度(A)、二尖瓣环室间隔侧舒张早期峰值速度(e'')、整体纵向应变(GLS)及整体圆周应变(GCS);以相关性分析及logistic回归分析观察HFpEF的影响因素。结果 组间LVEDD、IVSD、LVPWD、LVEF、GLS及GCS差异均有统计学意义(P均＜0.05)。HFpEF组GLS与E、E/A、LVEF呈负相关(r＝－0.287、－0.207、－0.449,P均＜0.01),与年龄、LVESD呈正相关(r=0.149、0.178,P均＜0.05);GCS与CAPP、IVSD、E、LVEF呈负相关(r＝－0.169、－0.189、－0.219、－0.604,P均＜0.05),与LVESD呈正相关(r=0.208,P＜0.01)。高血压和GCS均为HFpEF的独立危险因素(P均＜0.05),CAPP、IVSD和LVPWD均为独立保护因素(P均＜0.05)。结论 初诊及未经治疗高血压患者左心室GCS有助于预测HFpEF,而GLS与HFpEF无明显相关性。     

Incremental value of cardiovascular magnetic resonance over echocardiography in the detection of acute and chronic myocardial infarction

Background

Although echocardiography is used as a first line imaging modality, its accuracy to detect acute and chronic myocardial infarction (MI) in relation to infarct characteristics as assessed with late gadolinium enhancement cardiovascular magnetic resonance (LGE-CMR) is not well described.

Methods

One-hundred-forty-one echocardiograms performed in 88 first acute ST-elevation MI (STEMI) patients, 2 (IQR1-4) days (n = 61) and 102 (IQR92-112) days post-MI (n = 80), were pooled with echocardiograms of 36 healthy controls. 61 acute and 80 chronic echocardiograms were available for analysis (53 patients had both acute and chronic echocardiograms). Two experienced echocardiographers, blinded to clinical and CMR data, randomly evaluated all 177 echocardiograms for segmental wall motion abnormalities (SWMA). This was compared with LGE-CMR determined infarct characteristics, performed 104 ± 11 days post-MI. Enhancement on LGE-CMR matched the infarct-related artery territory in all patients (LAD 31%, LCx 12% and RCA 57%).

Results

The sensitivity of echocardiography to detect acute MI was 78.7% and 61.3% for chronic MI; specificity was 80.6%. Undetected MI were smaller, less transmural, and less extensive (6% [IQR3-12] vs. 15% [IQR9-24], 50 ± 14% vs. 61 ± 15%, 7 ± 3 vs. 9 ± 3 segments, p < 0.001 for all) and associated with higher left ventricular ejection fraction (LVEF) and non-anterior location as compared to detected MI (58 ± 5% vs. 46 ± 7%, p < 0.001 and 82% vs. 63%, p = 0.03). After multivariate analysis, LVEF and infarct size were the strongest independent predictors of detecting chronic MI (OR 0.78 [95%CI 0.68-0.88], p < 0.001 and OR 1.22 [95%CI0.99-1.51], p = 0.06, respectively). Increasing infarct transmurality was associated with increasing SWMA (p < 0.001).

Conclusions

In patients presenting with STEMI, and thus a high likelihood of SWMA, the sensitivity of echocardiography to detect SWMA was higher in the acute than the chronic phase. Undetected MI were smaller, less extensive and less transmural, and associated with non-anterior localization and higher LVEF. Further work is needed to assess the diagnostic accuracy in patients with non-STEMI.     

Normal values for cardiovascular magnetic resonance in adults and children

Morphological and functional parameters such as chamber size and function, aortic diameters and distensibility, flow and T1 and T2* relaxation time can be assessed and quantified by cardiovascular magnetic resonance (CMR). Knowledge of normal values for quantitative CMR is crucial to interpretation of results and to distinguish normal from disease. In this review, we present normal reference values for morphological and functional CMR parameters of the cardiovascular system based on the peer-reviewed literature and current CMR techniques and sequences.

Electronic supplementary material

The online version of this article (doi:10.1186/s12968-015-0111-7) contains supplementary material, which is available to authorized users.     

The role of cardiovascular magnetic resonance in the evaluation of patients with heart failure

Chronic heart failure is a common disorder placing significant burdens on patients and health-care services. Noninvasive imaging plays a central role in accurate diagnosis, determination of etiology and prognosis, and in monitoring therapy. Advances in technology mean cardiovascular magnetic resonance (CMR) imaging has established itself as both a valuable clinical and research tool in this arena. Not only is CMR the new gold standard for accurate and reproducible assessment of ventricular volumes and mass, but by using gadolinium contrast, underlying pathology can often be determined. In ischemic cardiomyopathy a 'one stop' assessment can be made of function, perfusion and mass. Continuing advances such as myocardial tagging and the increasing availability of CMR mean that it will become an increasingly important and useful tool for clinicians looking after patients with cardiomyopathy and heart failure.     

Determinants of hypertension and left ventricular function in end stage renal failure: a pilot study using cardiovascular magnetic resonance imaging

Cardiovascular disease is the principal cause of mortality in patients with renal failure. Left ventricular (LV) abnormalities are adverse prognostic indicators for cardiovascular outcome. The aim of this study was to use cardiac magnetic resonance scanning (CMR) to define LV functional abnormalities in haemodialysis (HD) patients and clarify the determinants of blood pressure (BP) and the effect of anaemia in this population. We studied 44 HD patients and 11 controls with CMR performed following dialysis. Forty patients and 11 controls completed the study. LV mass (P<0.001) and estimated systemic vascular resistance (SVR) (P = 0.002) were significantly higher in the dialysis group compared to controls. LV ejection fraction (P = 0.002) and SV (P = 0.043) were lower than controls. In the HD patients, BP correlated significantly with cardiac output (CO; r = 0.569, P<0.001) and end diastolic volume (EDV; r = 0.565, P<0.001) but there was no correlation between BP and SVR (r = 0.201, P = 0.594). Haemoglobin was inversely correlated with both CO (r = -0.531, P<0.001) and EDV (r = -0.493, P = 0.001) and positively with SVR (r = 0.402, P = 0.009). HD patients had a higher LV mass and lower ejection fraction than controls. The relationship of BP with CO, but not SVR, supports the theory that a major determinant of BP is intravascular volume and CO rather than vascular resistance although there was a fixed increase in SVR in this population. Improved understanding of the mechanisms underlying increased SVR and improved control of CO and intravascular volume may allow better therapeutic strategies. CMR provides insights into the pathophysiology of hypertension and LV dysfunction in HD patients.     

Guidelines and protocols for cardiovascular magnetic resonance in children and adults with congenital heart disease: SCMR expert consensus group on congenital heart disease

Cardiovascular magnetic resonance (CMR) has taken on an increasingly important role in the diagnostic evaluation and pre-procedural planning for patients with congenital heart disease. This article provides guidelines for the performance of CMR in children and adults with congenital heart disease. The first portion addresses preparation for the examination and safety issues, the second describes the primary techniques used in an examination, and the third provides disease-specific protocols. Variations in practice are highlighted and expert consensus recommendations are provided. Indications and appropriate use criteria for CMR examination are not specifically addressed.     

The interplay between metabolic alterations,diastolic strain rate and exercise capacity in mild heart failure with preserved ejection fraction: a cardiovascular magnetic resonance study

Background

Heart failure (HF) is characterized by altered myocardial substrate metabolism which can lead to myocardial triglyceride accumulation (steatosis) and lipotoxicity. However its role in mild HF with preserved ejection fraction (HFpEF) is uncertain. We measured myocardial triglyceride content (MTG) in HFpEF and assessed its relationships with diastolic function and exercise capacity.

Methods

Twenty seven HFpEF (clinical features of HF, left ventricular EF >50%, evidence of mild diastolic dysfunction and evidence of exercise limitation as assessed by cardiopulmonary exercise test) and 14 controls underwent ¹H-cardiovascular magnetic resonance spectroscopy (¹H-CMRS) to measure MTG (lipid/water, %), ³¹P-CMRS to measure myocardial energetics (phosphocreatine-to-adenosine triphosphate - PCr/ATP) and feature-tracking cardiovascular magnetic resonance (CMR) imaging for diastolic strain rate.

Results

When compared to controls, HFpEF had 2.3 fold higher in MTG (1.45?±?0.25% vs. 0.64?±?0.16%, p?=?0.009) and reduced PCr/ATP (1.60?±?0.09 vs. 2.00?±?0.10, p?=?0.005). HFpEF had significantly reduced diastolic strain rate and maximal oxygen consumption (VO₂ max), which both correlated significantly with elevated MTG and reduced PCr/ATP. On multivariate analyses, MTG was independently associated with diastolic strain rate while diastolic strain rate was independently associated with VO₂ max.

Conclusions

Myocardial steatosis is pronounced in mild HFpEF, and is independently associated with impaired diastolic strain rate which is itself related to exercise capacity. Steatosis may adversely affect exercise capacity by indirect effect occurring via impairment in diastolic function. As such, myocardial triglyceride may become a potential therapeutic target to treat the increasing number of patients with HFpEF.