Echocardiography in inflammatory heart disease: A comparison of giant cell myocarditis, cardiac sarcoidosis, and acute non-fulminant myocarditis.

Background: Giant cell myocarditis (GCM) and cardiac sarcoidosis (CS) are, in contrast to acute non-fulminant myocarditis (ANFM), rare inflammatory diseases of the myocardium with poor prognosis. Although echocardiography is the first-line diagnostic tool in these patients, their echocardiographic appearance has so far not been systematically studied. Methods: We assessed a total of 71 patients with endomyocardial biopsy-proven GCM (n = 21), and CS (n = 25), as well as magnetic resonance-verified ANFM (n = 25). All echocardiographic examinations, performed upon clinical presentation, were reanalysed according to current guidelines including a detailed assessment of right ventricular (RV) dysfunction. Results: In comparison with ANFM, patients with either GCM or CS were older (mean age (±SD) 55 ± 12 or 53 ± 8 vs 25 ± 8 years), more often of female gender (52% or 24% vs 8%), had more severe clinical symptoms and higher natriuretic peptide levels. For both GCM and CS, echocardiography revealed more frequently signs of left ventricular (LV) dysfunction in form of a reduced ejection fraction (p < 0.001), decreased cardiac index (p < 0.001) and lower global longitudinal strain (p < 0.001) in contrast to ANFM. The most prominent increase in LV end-diastolic volume index was observed in CS. In addition, RV dysfunction was more frequently found in both GCM and CS than in ANFM (p = 0.042). Conclusions: Both GCM and CS have an echocardiographic and clinical appearance that is distinct from ANFM. However, the method cannot further differentiate between the two rare entities. Consequently, echocardiography can strengthen the initial clinical suspicion of a more severe form of myocarditis, thus warranting a more rigorous clinical work-up.

Cardiovascular Magnetic Resonance in Myocarditis.

Myocarditis is an inflammatory disease of the myocardium, and its diagnosis remains challenging owing to a varying clinical presentation and broad spectrum of underlying aetiologies. In clinical practice, cardiovascular magnetic resonance has become an invaluable non-invasive imaging tool in the evaluation of patients with clinically suspected myocarditis, mainly thanks to its unique multiparametric tissue characterization ability. Although considered as useful, the method also has its limitations. This review aims to provide an up-to-date overview of the strengths and weaknesses of cardiovascular magnetic resonance in the diagnostic work-up of patients with clinically suspected myocarditis in a broad clinical context.

Importance of through-plane heart motion correction for the assessment of aortic regurgitation severity using phase contrast magnetic resonance imaging.

PURPOSE: To elucidate the influence of through-plane heart motion on the assessment of aortic regurgitation (AR) severity using phase contrast magnetic resonance imaging (PC-MRI). APPROACH: A patient cohort with chronic AR (n = 34) was examined with PC-MRI. The regurgitant volume (RVol) and fraction (RFrac) were extracted from the PC-MRI data before and after through-plane heart motion correction and was then used for assessment of AR severity. RESULTS: The flow volume errors were strongly correlated to aortic diameter (R = 0.80, p < 0.001) with median (IQR 25%;75%): 16 (14; 17) ml for diameter>40mm, compared with 9 (7; 10) ml for normal aortic size (p < 0.001). RVol and RFrac were underestimated (uncorrected:64 ± 37 ml and 39 ± 17%; corrected:76 ± 37 ml and 44 ± 15%; p < 0.001) and ~ 20% of the patients received lower severity grade without correction. CONCLUSION: Through-plane heart motion introduces relevant flow volume errors, especially in patients with aortic dilatation that may result in underestimation of the severity grade in patients with chronic AR.

The usefulness of left ventricular volume and aortic diastolic flow reversal for grading chronic aortic regurgitation severity - Using cardiovascular magnetic resonance as reference.

Echocardiographic evaluation of chronic aortic regurgitation (AR) severity can lead to diagnostic ambiguity due to few feasible parameters or incongruent findings. The aim of the present study was to improve the diagnostic usefulness of left ventricular (LV) enlargement and aortic end-diastolic flow velocity (EDFV) using cardiovascular magnetic resonance (CMR) as reference. Patients (n = 120) were recruited either prospectively (n = 45) or retrospectively (n = 75). Severe AR (CMR regurgitant fraction > 33%) was present in 51% and 93% of the patients had LV ejection fraction ≥ 50%. EDFV and LV end-diastolic volume index (EDVI) were assessed by echocardiography using the traditional (excluding trabeculae) and recommended approach (including trabeculae). The patients were randomised to a derivation (n = 60) or a test group (n = 60). EDVI (traditional/recommended) to rule in (>99/118 ml/m2) and rule out severe AR (≤75/87 ml/m2) were identified using ROC analyses in the derivation group. The corresponding thresholds for EDFV were >17 cm/s and ≤10 cm/s. In the test group, the positive/negative likelihood ratios to rule in/rule out severe AR using EDVI were 10.0/0.14 (traditional), 6.2/0.11 (recommended), and using EDFV were 10.2/0.08. To rule in and rule out severe AR using derived cut-off values instead of >2 SD reduced the false positives by 92%, whereas using EDFV ≤10 cm/s instead of ≤20 cm/s reduced the false negatives by 94%. In conclusion, EDVI and EDFV as quantitative parameters are useful to rule in or rule out severe chronic AR. Importantly, other causes of LV enlargement have to be considered.

Importance of complex blood flow in the assessment of aortic regurgitation severity using phase contrast magnetic resonance imaging.

This study aimed to investigate if and how complex flow influences the assessment of aortic regurgitation (AR) using phase contrast MRI in patients with chronic AR. Patients with moderate (n = 15) and severe (n = 28) chronic AR were categorized into non-complex flow (NCF) or complex flow (CF) based on the presence of systolic backward flow volume. Phase contrast MRI was performed repeatedly at the level of the sinotubular junction (Ao1) and 1 cm distal to the sinotubular junction (Ao2). All AR patients were assessed to have non-severe AR or severe AR (cut-off values: regurgitation volume (RVol) ≥ 60 ml and regurgitation fraction (RF) ≥ 50%) in both measurement positions. The repeatability was significantly lower, i.e. variation was larger, for patients with CF than for NCF (≥ 12 ± 12% versus ≥ 6 ± 4%, P ≤ 0.03). For patients with CF, the repeatability was significantly lower at Ao2 compared to Ao1 (≥ 21 ± 20% versus ≥ 12 ± 12%, P ≤ 0.02), as well as the assessment of regurgitation (RVol: 42 ± 34 ml versus 54 ± 42 ml, P < 0.001; RF: 30 ± 18% versus 34 ± 16%, P = 0.01). This was not the case for patients with NCF. The frequency of patients that changed in AR grade from severe to non-severe when the position of the measurement changed from Ao1 to Ao2 was higher for patients with CF compared to NCF (RVol: 5/26 (19%) versus 1/17 (6%), P = 0.2; RF: 4/26 (15%) versus 0/17 (0%), P = 0.09). Our study shows that complex flow influences the quantification of chronic AR, which can lead to underestimation of AR severity when using PC-MRI.

Cardiac involvement in critically ill and mechanically ventilated patients with COVID-19 - a prospective, observational echocardiographic study.

INTRODUCTION: In this prospective, observational study, we have evaluated right (RV) and left (LV) ventricular function with echocardiography and correlated it to the levels of biomarkers, hs-TNT, NT-pro-BNP, D-dimer and fibrinogen. In a subgroup, we have evaluated the effect of inhaled milrinone on RV afterload and function. METHODS: Thirty-one ICU patients with COVID-19 in need of mechanical ventilation and norepinephrine infusion were prospectively included. Hemodynamic and respiratory variables were measured at the time of the echocardiographic examination and biomarkers were obtained on arrival at the ICU and then followed up routinely. Eight patients received inhaled aerosolized milrinone at a dose of 2.5 mg/hour. RESULTS: The most common echocardiographic pattern was RV dilation with or without systolic dysfunction, which was found in 62% of patients. Pulmonary acceleration time was abnormal in 55% and indices of RV systolic function, such as fractional area of change, RV strain, were abnormal in 30% and 31% of patients respectively. A cardiac index of < 2.5 l/min*m2 was seen in 58% of the patients. Left ventricular ejection fraction and global left ventricular strain were impaired in 10% and 16% respectively. The correlation between echocardiographic variables and cardiac biomarkers was poor. RV afterload correlated well to the levels of D-dimer. Milrinone inhalation did not improve RV function or afterload. CONCLUSION: RV dysfunction was the most common finding. The poor correlation to cardiac biomarkers argues against extensive myocardial involvement. The lack of improvement in RV function after milrinone inhalation suggests that the most likely cause of RV dysfunction is increased RV afterload caused by pulmonary thrombosis/embolism.

Evaluation of the Integrative Algorithm for Grading Chronic Aortic and Mitral Regurgitation Severity Using the Current American Society of Echocardiography Recommendations: To Discriminate Severe from Moderate Regurgitation.

BACKGROUND: The recently published integrative algorithms for echocardiographic grading of native aortic regurgitation (AR) and mitral regurgitation (MR) by the American Society of Echocardiography are consensus based and have not been evaluated. Thus, the aims of the present study were to investigate the feasibility of individual parameters and to evaluate the ability of the algorithms to discriminate severe from moderate regurgitation. METHODS: This prospective study comprised 93 patients with chronic AR (n = 45) and MR (n = 48). All patients underwent echocardiography and cardiovascular magnetic resonance within 4 hours. The algorithms were evaluated using two different definitions for severe regurgitation: (1) a cardiovascular magnetic resonance standard indicating future need for valve surgery and (2) a clinical standard using patients who underwent valve surgery with proven postoperative left ventricular reverse remodeling and improved functional class (AR/MR, n = 26/26). RESULTS: The feasibility of the criteria in the first step of the algorithm was higher (AR/MR, 95%/91%) compared with the second step using quantitative Doppler parameters (74%/57%). For the AR algorithm, sensitivity was 95% and specificity 44%, whereas for the MR algorithm, sensitivity was 73% and specificity 92%. Among patients with benefit of surgery, the algorithms correctly identified 77%, misclassified 8%, and were inconclusive in 15% of the patients with AR; the corresponding figures were 73%, 15%, and 12% in the patients with MR. CONCLUSIONS: Using cardiovascular magnetic resonance as reference, the recommended algorithms for grading of regurgitation have the ability to rule out severe AR and rule in severe MR. The quantitative Doppler methods are hampered by feasibility issues, and our findings suggest that the decision regarding surgical intervention in symptomatic patients with discordant or inconclusive echocardiographic grading should be based on a consolidated assessment of clinical and multimodality findings.

Pulsed-Wave Doppler Recordings in the Proximal Descending Aorta in Patients with Chronic Aortic Regurgitation: Insights from Cardiovascular Magnetic Resonance.

BACKGROUND: The pulsed-wave Doppler recording in the descending aorta (PWDDAO) is one of the parameters used in grading aortic regurgitation (AR) severity. The aim of the present study was to investigate the assessment of chronic AR by PWDDAO with insights from cardiovascular magnetic resonance (CMR). METHODS: This prospective study comprised 40 patients investigated with echocardiography and CMR within 4 hours either prior to valve surgery (n = 23) or as part of their follow-up (n = 17) due to moderate or severe AR. End-diastolic flow velocity (EDFV) and the diastolic velocity time integral (dVTI) were measured. The appearance of diastolic forward flow (DFF) was noted. Phase-contrast flow rate curves were obtained in the DAO. RESULTS: Twenty-five patients had severe and eight had moderate AR by echocardiography (seven were indeterminate). The EDFV was below the recommended threshold (>20 cm/sec) in 13 patients (52%) with severe AR. Lowering the EDFV threshold (>13 cm/sec) and with a dVTI threshold >13 cm showed negative likelihood ratios of 0.27 and 0.09, respectively. Detection of DFF with PWDDAO identified a nonuniform velocity profile by CMR with positive and negative likelihood ratios of 7.0 and 0.19, respectively. The relation between EDFV and DAO regurgitant volume (DAO-RVolCMR) was strong in patients without (R = 0.88) and weak in patients with DFF (R = 0.49). The DAO-RVolCMR as a percent of the total RVolCMR decreased with increasing ascending aorta (AAO) size and increased with increasing AR severity. CONCLUSIONS: Our findings suggest that PWDDAO provides semiquantitative parameters useful to assess chronic AR severity. The limitations are related to nonuniform velocity contour and variable degree of lower body contribution, which depends on AR severity but also on the AAO size.

Characterization of complex flow patterns in the ascending aorta in patients with aortic regurgitation using conventional phase-contrast velocity MRI.

Ascending aorta (AA) flow displacement (FD) is a surrogate for increased wall shear stress. We prospectively studied the flow profile in the AA in patients with aortic regurgitation (AR), to identify predictors of FD and investigate whether magnetic resonance imaging (MRI) phase-contrast flow rate curves (PC-FRC) contain quantitative information related to FD. Forty patients with chronic moderate (n = 14) or severe (n = 26) AR (21 (53%) with bicuspid aortic valve) and 22 controls were investigated. FD was determined from phase-contrast velocity profiles and defined as the distance between the center of the lumen and the "center of velocity" of the peak systolic forward flow or the peak diastolic negative flow, normalized to the lumen radius. Forward and backward volume flow was determined separately for systole and diastole. Seventy percent had systolic backward flow and 45% had diastolic forward flow in large areas of the vessel. AA dimension was an independent predictor of systolic FD while AA dimension and regurgitant volume were independent predictors of diastolic FD. Valve phenotype was not an independent predictor of systolic or diastolic FD. The linear relationships between systolic backward flow and systolic FD and diastolic forward flow and diastolic FD were strong (R = 0.77 and R = 0.76 respectively). Systolic backward flow and diastolic forward flow identified marked systolic and diastolic FD (≥0.35) with a positive likelihood ratio of 6.0 and 10.8, respectively. In conclusion, conventional PC-FRC data can detect and quantify FD in patients with AR suggesting the curves as a research and screening tool in larger patient populations.

Characterization of Chronic Aortic and Mitral Regurgitation Undergoing Valve Surgery Using Cardiovascular Magnetic Resonance.

Grading of chronic aortic regurgitation (AR) and mitral regurgitation (MR) by cardiovascular magnetic resonance (CMR) is currently based on thresholds, which are neither modality nor quantification method specific. Accordingly, this study sought to identify CMR-specific and quantification method-specific thresholds for regurgitant volumes (RVols), RVol indexes, and regurgitant fractions (RFs), which denote severe chronic AR or MR with an indication for surgery. The study comprised patients with moderate and severe chronic AR (n = 38) and MR (n = 40). Echocardiography and CMR was performed at baseline and in all operated AR/MR patients (n = 23/25) 10 ± 1 months after surgery. CMR quantification of AR: direct (aortic flow) and indirect method (left ventricular stroke volume [LVSV] - pulmonary stroke volume [PuSV]); MR: 2 indirect methods (LVSV - aortic forward flow [AoFF]; mitral inflow [MiIF] - AoFF). All operated patients had severe regurgitation and benefited from surgery, indicated by a significant postsurgical reduction in end-diastolic volume index and improvement or relief of symptoms. The discriminatory ability between moderate and severe AR was strong for RVol >40 ml, RVol index >20 ml/m2, and RF >30% (direct method) and RVol >62 ml, RVol index >31 ml/m2, and RF >36% (LVSV-PuSV) with a negative likelihood ratio ≤ 0.2. In MR, the discriminatory ability was very strong for RVol >64 ml, RVol index >32 ml/m2, and RF >41% (LVSV-AoFF) and RVol >40 ml, RVol index >20 ml/m2, and RF >30% (MiIF-AoFF) with a negative likelihood ratio < 0.1. In conclusion, CMR grading of chronic AR and MR should be based on modality-specific and quantification method-specific thresholds, as they differ largely from recognized guideline criteria, to assure appropriate clinical decision-making and timing of surgery.

Left ventricular volumes by echocardiography in chronic aortic and mitral regurgitations.

Objectives Cut-off values for left ventricular (LV) dimensions indicating severe valve regurgitation have not been defined. The aim of this study was to establish echocardiographic cut-off values for LV dimensions indicating severe chronic aortic (AR) or mitral (MR) regurgitation. Design The hemodynamic significance was confirmed by documented reduction of end-diastolic volume (EDV) and symptom relief after surgery. Eighty-three patients with moderate or severe regurgitation (AR, n = 41; MR, n = 42) without other cardiac conditions underwent prospectively two-dimensional (2DE), real-time three-dimensional (RT3DE) echocardiography and cardiovascular magnetic resonance (CMR) exams within 4 h. Results The relationship between EDVCMR and EDV2DE and EDVRT3DE were strong (R 0.95 and 0.91). EDV index cut-offs for 2DE/RT3DE >87/104 ml/m(2) identified AR patients with severe regurgitation with a positive likelihood ratio (PLR) of 5.0/5.0. The corresponding in patients with MR EDV index cut-offs were >69/87 ml/m(2) with a PLR of 14.9/5.5. LV linear dimensions could not identify patients with severe regurgitation. Conclusions LV volumes by echocardiography can support the diagnosis of severe chronic regurgitation. Importantly, other causes for LV enlargement have to be considered.

Mitral regurgitation quantification by cardiovascular magnetic resonance: a comparison of indirect quantification methods.

Quantification of mitral regurgitation (MR) using cardiovascular magnetic resonance can be achieved by three indirect methods. The aims of the study were to determine their agreement, observer variability and effect on grading MR severity. The study comprised 16 healthy volunteers and 36 MR patients. Quantification was performed using the 'standard' [left ventricular stroke volume (LVSV)-aortic forward flow (AoFF)], 'volumetric' [LVSV-right ventricular stroke volume (RVSV)] and 'flow' method [mitral inflow (MiIF)-AoFF]. In healthy volunteers without MR, LVSV was larger than AoFF (mean difference ±SD: 12 ± 6 ml, P < 0.0001). Only small differences were found between LVSV-RVSV (3 ± 6 ml) and MiIF-AoFF (1 ± 5 ml). In patients, mitral regurgitant volumes (MRVs)/fractions (MRFs) were larger (P < 0.0001) using the 'standard' method (90 ± 31 ml/51 ± 11%) compared with the 'volumetric' (76 ± 30 ml/42 ± 11%) and 'flow' method (70 ± 32 ml/44 ± 15%). Inter-observer variability was lowest for the 'flow' and highest for the 'volumetric' method, while intra-observer variability was similar for all three methods. In 29 operated patients with severe MR, MRVs were above the guideline threshold (≥60 ml) in 100, 86 and 83% of the cases, and MRFs were above the threshold (≥50%) in 76, 32 and 48% of the cases, when using the 'standard', 'volumetric' and 'flow' method respectively. In conclusion, the choice of method can affect the grading of MR severity and thereby eventually the clinical decision-making and timing of surgery.

Quantification of Left Ventricular Linear, Areal and Volumetric Dimensions: A Phantom and in Vivo Comparison of 2-D and Real-Time 3-D Echocardiography with Cardiovascular Magnetic Resonance.

Two-dimensional echocardiography and real-time 3-D echocardiography have been reported to underestimate human left ventricular volumes significantly compared with cardiovascular magnetic resonance. We investigated the ability of 2-D echocardiography, real-time 3-D echocardiography and cardiovascular magnetic resonance to delineate dimensions of increasing complexity (diameter-area-volume) in a multimodality phantom model and in vivo, with the aim of elucidating the main cause of underestimation. All modalities were able to delineate phantom dimensions with high precision. In vivo, 2-D and real-time 3-D echocardiography underestimated short-axis end-diastolic linear and areal and all left ventricular volumetric dimensions significantly compared with cardiovascular magnetic resonance, but not short-axis end-systolic linear and areal dimensions. Underestimation increased successively from linear to volumetric left ventricular dimensions. When analyzed according to the same principles, 2-D and real-time 3-DE echocardiography provided similar left ventricular volumes. In conclusion, echocardiographic underestimation of left ventricular dimensions is due mainly to inherent technical differences in the ability to differentiate trabeculated from compact myocardium. Identical endocardial border definition criteria are needed to minimize differences between the modalities and to ensure better comparability in clinical practice.

Baroreflex effectiveness index and baroreflex sensitivity predict all-cause mortality and sudden death in hypertensive patients with chronic renal failure.

OBJECTIVES: Impaired arterial baroreflex sensitivity (BRS) has been associated with cardiac mortality and non-fatal cardiac arrests after a myocardial infarction. Patients with chronic renal failure (CRF) have a poor prognosis because of cardiovascular diseases, and sudden death is common. The aim of this study was to assess whether BRS or the baroreflex effectiveness index (BEI), a novel index reflecting the number of times the baroreflex is active in controlling the heart rate in response to blood pressure fluctuations, is associated with prognosis in CRF. METHODS: Hypertensive patients with CRF who were treated conservatively, by haemodialysis or peritoneal dialysis were studied. Electrocardiogram and beat-to-beat blood pressures were recorded continuously and BRS and BEI were calculated. Patients were then followed prospectively for 41 +/- 15 months (range 1-64). RESULTS: During follow-up 69 patients died. Cardiovascular diseases and uraemia accounted for the majority of deaths (60 and 20%, respectively), whereas sudden death occurred in 15 patients. In adjunct with established risk factors such as age, diabetes, congestive heart failure and diastolic blood pressure, reduced BEI was an independent predictor of all-cause mortality among CRF patients [relative risk (RR) 0.50, 95% confidence interval (CI) 0.33-0.71 for an increase of one standard deviation in BEI, P < 0.001]. Diabetes and reduced BRS were independent predictors of sudden death (RR 0.29, 95% CI 0.09-0.86 for an increase of one standard deviation in BRS, P=0.022). CONCLUSIONS: Both BEI and BRS convey prognostic information that may have clinical implications for patients with cardiovascular diseases in general.

Reduced baroreflex effectiveness index in hypertensive patients with chronic renal failure.

BACKGROUND: Impaired arterial baroreflex function has been associated with an increased risk of ventricular arrhythmia and sudden death. This has also been suggested for patients with chronic renal failure (CRF) who are at high risk for cardiovascular morbidity. The aim of this study was to investigate the arterial baroreflex function in CRF patients with emphasis on analyzing the time during which the arterial baroreflex is active, the baroreflex effectiveness index (BEI). METHODS: Beat-to-beat blood pressure (measured with Portapres) and electrocardiography were continuously registered during 30 min rest in 216 hypertensive CRF patients on hemodialysis (n=95), continuous ambulatory peritoneal dialysis (n=59), or conservative treatment (n=59). The spontaneous sequence method was used to calculate BRS and BEI. Age-matched healthy subjects (n=43) were examined for comparison. RESULTS: The BRS was reduced by 51% and the BEI by 49% in CRF patients compared with healthy subjects (P<.001 for both). In addition, CRF patients with diabetes showed further reductions compared with patients without diabetes (15% reduction of BRS and 44% of BEI, P<.01 for both). The treatment modality for renal failure had no effect on BRS or BEI. In a multivariate linear regression analysis, age, body mass index, and systolic blood pressure were independent predictors of BRS, whereas age and diabetes were independent predictors of BEI in patients with CRF. CONCLUSIONS: We conclude that BEI, which is markedly reduced in hypertensive patients with CRF, may convey information on arterial baroreflex function that is complementary to BRS.

Reproducibility of methods for assessing baroreflex sensitivity and temporal QT variability in end-stage renal disease and healthy subjects.

Spontaneous baroreflex sensitivity (BRS), the reflex heart rate modulation in response to blood pressure changes (predominantly an index of cardiac vagal activity) and temporal QT variability (an index of myocardial repolarization) have been demonstrated to convey important prognostic information. The information about reproducibility of BRS and temporal QT variability is limited and there is lack of information regarding patients with cardiovascular diseases. We investigated reproducibility of spontaneous BRS using the sequence technique and temporal QT variability index (QTVI) in terms of intra-, interexaminer and within-subject variability in end-stage renal disease patients (ESRD, n=17, age 55+/-14 years) and healthy subjects (HS, n=29, age 32+/-12 years, P<0.01). ECG and blood pressure (Portapres) were recorded on two separate days and BRS and QTVI were evaluated by two independent examiners. The mean heart rate was similar in ESRD patients in comparison to healthy controls, whereas the mean arterial pressure was 13 % higher in ESRD patients (P<0.01). Spontaneous BRS was 62% lower (P<0.01) and QTVI was 41% higher in ESRD patients (P<0.01) compared to healthy subjects, respectively. Coefficient of variation (CV) of within-subject reproducibility of BRS and QTVI measurements was moderate (BRS: 33 % for ESRD, 27% for HS; QTVI: 40% for ESRD, 18% for HS). The 95% limit of within-subject reproducibility of BRS measurements was 3.8 ms/mm Hg for ESRD patients and 8.1 ms/mm Hg for healthy subjects; whereas the 95% limit of reproducibility of within-subject reproducibility of QTVI measurements was 0.73 for ESRD patients and 0.55 for healthy subjects. Concordance correlation coefficients of within-subject variability of BRS and QTVI were between 0.74 and 0.83 in both groups. CV of intra- and inter-examiner reproducibility of BRS and QTVI measurements in both groups ranged between 1 and 11%. In conclusion, the intra- and inter-examiner reproducibility/agreement of BRS and QTVI were high, whereas the within-subject reproducibility of these two methods was moderate, in both ESRD patients and healthy subjects. Thus, small differences in BRS and QTVI in longitudinal/interventional studies should be interpreted with caution.

Elevated temporal QT variability index in patients with chronic renal failure.

Patients with CRF (chronic renal failure) are at increased risk of cardiovascular diseases, and 60% of cardiovascular mortality in CRF is attributed to sudden death. Various abnormalities in myocardial repolarization are associated with the risk of ventricular arrhythmia. The aim of this study was to evaluate an index of temporal myocardial repolarization lability, the temporal QTVI (QT variability index), in patients with CRF. ECGs were recorded in 153 patients with CRF on haemodialysis (n=67), continuous ambulatory peritoneal dialysis (n=43) or conservative treatment (n=43) during 30 min of rest. QTVI was calculated as the logarithm of the ratio between the variances of the normalized QT and RR intervals. Age-matched healthy subjects (n=39) were examined for comparison. QTVI was increased by 47% in CRF patients compared with healthy subjects (-0.82+/-0.56 compared with -1.54+/-0.27 respectively; P<0.01). QTVI did not differ among patients on dialysis or conservative treatment, whereas QTVI was elevated further in patients with diabetes compared with non-diabetic CRF patients (-0.56+/-0.54 compared with -0.94+/-0.52 respectively; P<0.01). In a multiple linear regression analysis, diabetes and a history of coronary artery disease were the only independent predictors of QTVI in the CRF population. The present study demonstrates that elevated QTVI in patients with CRF is associated with diabetes and coronary disease. The present findings are important given that repolarization instability may predispose to ventricular arrhythmia and sudden death, events that occur frequently in CRF patients.

Reduced spontaneous baroreceptor sensitivity in patients with renovascular hypertension.

OBJECTIVE: Sympathetic nerve activity is increased in hypertensive patients with renal artery stenosis. Less is known about cardiac vagal function in these patients before and after renal angioplasty. The aim of the present study was to investigate cardiac baroreceptor reflex sensitivity together with total body noradrenaline (NA) spillover in hypertensive patients with renal artery stenosis before, and in some patients, 1 year after renal angioplasty. MATERIAL AND METHODS: Spontaneous baroreceptor reflex sensitivity and total body noradrenaline (NA) spillover were measured in patients with renovascular hypertension before intervention (n = 18), patients being cured/improved 1 year after renal angioplasty (n = 5) and age-matched healthy subjects (n = 25). RESULTS: Hypertensive patients with renal artery stenosis had higher total body NA spillover (4630 +/- 619 versus 3132 +/- 210 pmol/min, P < 0.05) and reduced cardiac baroreceptor reflex sensitivity (6.1 +/- 1.0 versus 10.7 +/- 1.0 ms/mmHg, P < 0.01) compared with healthy subjects. Similar results were obtained (before intervention) in a subgroup of patients (n = 9) with renovascular hypertension defined as cured/improved 1 year following renal angioplasty. Baroreceptor reflex sensitivity improved after renal angioplasty in a subset of patients showing good blood pressure control 1 year after intervention (6.4 +/- 0.7 to 9.4 +/- 1.7 ms/mmHg, P < 0.05). CONCLUSIONS: Patients with renovascular hypertension showed reduced cardiac baroreceptor reflex sensitivity and increased noradrenergic activity, which to some extent was reversed 1 year following successful renal angioplasty.

Autonomic control of the heart and renal vascular bed during autonomic dysreflexia in high spinal cord injury.

Autonomic function and hemodynamics were studied in nine spinal cord injured (SCI) subjects, at rest and during peripheral afferent stimulation, bladder percussion. Nine able-bodied subjects were studied for comparison during unstimulated conditions. Spontaneous baroreceptor reflex sensitivity was calculated from recordings of ECG and intraarterial blood pressure. An index of sympathetic activity was provided by measuring total body noradrenaline (NA) spillover by isotope dilution technique. Renal vascular resistance was calculated from PAH-clearance.SCI subjects had lower total body NA spillover (1011 +/- 193 vs 2261 +/- 328 pmol/min, P < 0.01), but similar baroreceptor reflex sensitivity and hemodynamics compared to able-bodied subjects at rest. In SCI group, during bladder percussion, mean arterial pressure increased (79 +/- 5 vs 113 +/- 8 mm Hg, P < 0.01), whereas heart rate was reduced during the first minute of the manoeuvre (62 +/- 2 vs 56 +/- 2 bpm, P < 0.05). Baroreceptor reflex sensitivity remained unchanged. Total body NA spillover and renal vascular resistance increased by 332 % (from 1004 +/- 218 pmol/min, P < 0.05) and 55 % (from 0.078 +/- 0.011 mmHg/ml/min, P < 0.05), respectively.SCI subjects demonstrated lower total body sympathetic outflow but normal baroreceptor reflex sensitivity at rest, suggesting a balanced autonomic output to the heart. Bladder percussion caused a substantial increase in renal vascular resistance and blood pressure, which was partly due to marked generalised sympathetic activation. This activation was counterbalanced by an increased vagal activity as evidenced by reduction of the heart rate.