Echocardiography-derived Indices Research Articles

Evaluation of left ventricular stiffness with echocardiography.

Half of patients with heart failure are presented with preserved ejection fraction (HFpEF). The pathophysiology of these patients is complex, but increased left ventricular (LV) stiffness has been proven to play a key role. However, the application of this parameter is limited due to the requirement for invasive catheterization for its measurement. With advances in ultrasound technology, significant progress has been made in the noninvasive assessment of LV chamber or myocardial stiffness using echocardiography. Therefore, this review aims to summarize the pathophysiological mechanisms, correlations with invasive LV stiffness constants, applications in different populations, as well as the limitations of echocardiography-derived indices for the assessment of both LV chamber and myocardial stiffness. Indices of LV chamber stiffness, such as the ratio of E/e' divided by left ventricular end-diastolic volume (E/e'/LVEDV), the ratio of E/SRe (early diastolic strain rates)/LVEDV, and diastolic pressure-volume quotient (DPVQ), are derived from the relationship between echocardiographic parameters of LV filling pressure (LVFP) and LV size. However, these methods are surrogate and lumped measurements, relying on E/e' or E/SRe for evaluating LVFP. The limitations of E/e' or E/SRe in the assessment of LVFP may contribute to the moderate correlation between E/e'/LVEDV or E/SRe/LVEDV and LV stiffness constants. Even the most validated measurement (DPVQ) is considered unreliable in individual patients. In comparison to E/e'/LVEDV and E/SRe/LVEDV, indices like time-velocity integral (TVI) measurements of pulmonary venous and transmitral flows may demonstrate better performance in assessing LV chamber stiffness, as evidenced by their higher correlation with LV stiffness constants. However, only one study has been conducted on the exploration and application of TVI in the literature, and the accuracy of assessing LV chamber stiffness remains to be confirmed. Regarding echocardiographic indices for LV myocardial stiffness evaluation, parameters such as epicardial movement index (EMI)/ diastolic wall strain (DWS), intrinsic velocity propagation of myocardial stretch (iVP), and shear wave imaging (SWI) have been proposed. While the alteration of DWS and its predictive value for adverse outcomes in various populations have been widely validated, it has been found that DWS may be better considered as an overall marker of cardiac function performance rather than pure myocardial stiffness. Although the effectiveness of iVP and SWI in assessing left ventricular myocardial stiffness has been demonstrated in animal models and clinical studies, both indices have their limitations. Overall, it seems that currently no echocardiography-derived indices can reliably and accurately assess LV stiffness, despite the development of several parameters. Therefore, a comprehensive evaluation of LV stiffness using all available parameters may be more accurate and enable earlier detection of alterations in LV stiffness.

Correlation between albuminuria and tissue Doppler-derived left ventricular myocardial performance index in patients with type 2 diabetes.

Albuminuria is considered as a significant predictor of cardiovascular morbidity and mortality in patients with diabetes mellitus. The main purpose of this study was to determine the correlation between albuminuria and global left ventricular (LV) function in patients with type 2 diabetes (T2D). This observational study was conducted on 80 consecutive asymptomatic patients with T2D and an LV ejection fraction ≥55%. The patients were divided into two groups depending on the presence or absence of albuminuria. Echocardiography-derived indices of the LV function were then compared between these groups. The patients with albuminuria were older (mean ± SD: 60.37 ± 9.05 vs 54.52 ± 10.26 years of age, P = .01) and had higher hemoglobin A1c (HbA1c) levels (8.45 ± 1.97 vs 7.25 ± 1.93 mg/dL, P = .012) than those without albuminuria. Among the echocardiographic variables, the patients with albuminuria had higher LV Tei-index (median [lower-upper quartile]: 0.620 [0.455-0.824] vs 0.441 [0.336-0.586], P < .001), more prolonged early filling (E)-wave deceleration time (274.87 ± 75.97 vs 239.40 ± 61.35 ms, P = .032), increased interventricular septal wall thickness (1.11 ± 0.31 vs 0.95 ± 0.21 cm, P = .012), and lower mean early diastolic mitral annular velocity (7.57 ± 2.34 vs 8.68 ± 2.46 cm/s, P = .046) than those without albuminuria. Among risk factors, only albuminuria and HbA1c levels were associated with a significant increase in LV Tei-index (Beta = 0.426 and P < .001, Beta = 0.226 and P = .042, respectively). The LV Tei-index was significantly higher in diabetic patients with than without albuminuria. Low HbA1c levels were correlated with a decrease in LV Tei-index.

Novel Echocardiography-Derived Left Ventricular Stiffness Index in Low-Flow Versus Normal-Flow Severe Aortic Stenosis with Preserved Left Ventricular Ejection Fraction

Background Paradoxical low-flow (LF) severe aortic stenosis (AS) with preserved left ventricular ejection fraction (LVEF) may have poorer prognosis than normal-flow (NF) AS, though its pathophysiology remained unclear. In particular, LV stiffness has not been compared between LF vs NF. We used a novel echocardiography-derived index of LV stiffness to compare between these groups. Consecutive patients with medically-managed isolated severe AS (aortic valve area < 1 cm2) and preserved LVEF (>50%) were studied. Echocardiographic LV stiffness index was measured by a method previously validated against cardiac catheterization. We compared LF (stroke volume index, SVI < 35 ml/m2) and NF severe AS. Of the 352 patients, 121 (34%) were LF. Both LF and NF groups had similar demographics, valve areas and indices. Compared to NF, LF severe AS had higher LV stiffness indices (>0.11 ml−1 OR 3.067, 95% CI 1.825–5.128, p < 0.001). Increased LV stiffness was associated with concentric remodelling and more severe diastolic dysfunction, especially in LF AS. An LV stiffness index of > 0.11 ml−1 was independently associated with increased mortality, after adjusting for age, clinical and echocardiographic parameters (HR 2.283 95% CI 1.318–3.968, p = 0.003). Non-invasive echocardiographic-derived index of LV stiffness may be important in LF AS. Increased LV stiffness was related to LV concentric remodelling and diastolic dysfunction, and associated with poorer clinical outcomes in medically-managed AS.

P2444Comparison of 3D and 2D echocardiography-derived indices of left ventricular function and structure to predict long-term mortality in the general population: Southall And Brent Revisited (SABRE) study

Abstract Background Three-dimensional echocardiography (3DE) may have advantages over two-dimensional echocardiography (2DE) for the assessment of left ventricular (LV) function and structure. However, studies comparing 3DE and 2DE-derived indices in relation to mortality are limited, particularly in the general population. Purpose We examined associations between 2DE and 3DE-derived LV ejection fractions (LVEF) and volumes for all-cause mortality in a population-based sample. Methods A total of 899 individuals (age, 69.6±6.1 years; 77.5%male) from the SABRE study, a UK-based tri-ethnic community cohort, underwent a comprehensive transthoracic echocardiography examination. 2D LVEF and volumes were calculated, and full-volume 3D LV datasets acquired over 4 sub-volumes were obtained using a matrix-array transducer and were analysed offline using Qlab advanced, v7.0. The associations between both 2D- and 3D-derived LVEF (≥55% vs. &lt;55%), body surface area indexed end-diastolic volume (iEDV) and end-systolic volume (iESV), and all-cause mortality were determined using Cox proportional hazards models. Survival curves were constructed using the Kaplan-Meier method. Results Of the 899 individuals, 118 (13.1%) died over a median follow-up period of 8 years to 2018. Kaplan Meier survival estimates (Figure 1 illustrates LVEF) and Cox regression revealed that 2D and 3D LVEF, iEDV and iESV were associated with increased risk of all-cause mortality (LVEF (≥55% vs. &lt;55%), 3DE: HR=0.53 (0.35, 0.80); 2DE: HR=0.51 (0.34, 0.75), iEDV (per 1SD increment), 3DE: HR=1.20 (1.0, 1.41); 2DE: HR=1.19 (1.0–1.41), iESV (per 1SD increment), 3DE: HR=1.27 (1.1, 1.52), 2DE: HR=1.32 (1.15, 0.1.51)). However, 3DE associations tended to be stronger in models adjusted for classical risk factors including age, sex, ethnicity, systolic blood pressure, cholesterol:HDL ratio, body mass index, antihypertensive medications, diabetes, and smoking (LVEF (≥55% vs. &lt;55%), 3DE: HR=0.59 (0.39, 0.90); 2DE: HR=0.69 (0.46, 1.0), iEDV (per 1SD increment), 3DE: HR=1.20 (1.0, 1.41); 2DE: HR=1.10 (0.93, 1.31), iESV (per 1SD increment), 3DE: HR=1.27 (1.1, 1.52), 2DE: HR=1.20 (1.04, 0.1.39)). Figure 1. Kaplan-Meier curves. Conclusions In this population-based study, both 2DE and 3DE-derived indices of LV structure and function were associated with all-cause mortality independently of classical risk factors, with some indication that strengths of association were greater for 3DE-derived indices. Acknowledgement/Funding SABRE is funded by BHF, Diabetes UK, the MRC and the Wellcome Trust. LA holds a scholarship grant from Imam Abdulrahman Bin Faisal University, SA

Human Induced Pluripotent Stem Cell–Derived Cardiomyocyte Patch in Rats With Heart Failure

To treat chronic heart failure (CHF), we developed a robust, easy to handle bioabsorbable tissue-engineered patch embedded with human neonatal fibroblasts and human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs). This patch was implanted on the epicardial surface of the heart covering the previously infarcted tissue. Sprague-Dawley rats (6-8 weeks old) underwent sham surgery (n= 12) or left coronary artery ligation (n= 45). CHF rats were randomized 3 weeks after ligation to CHF control with sham thoracotomy (n= 21), or a fibroblasts/hiPSC-CMs patch (n= 24) was implanted. All sham surgery rats also underwent a sham thoracotomy. At 3 weeks after randomization, hemodynamics, echocardiography, electrophysiologic, and cell survival studies were performed. Patch-treated rats had decreased (P < .05) left ventricular-end diastolic pressure and the time constant of left ventricular relaxation (Tau), increased anterior wall thickness in diastole, and improved echocardiography-derived indices of diastolic function (E/e' [ratio of early peak flow velocity to early peak LV velocity] and e'/a' [ratio of early to late peak left ventricular velocity]). All rats remained in normal sinus rhythm, with no dysrhythmias. Rats treated with the patch showed improved electrical activity. Transplanted hiPSC-CMs were present at 7 days but not detected at 21 days after implantation. The patch increased (P < .05) gene expression of vascular endothelial growth factor, angiopoietin 1, gap junction α-1 protein (connexin 43), β-myosin heavy 7, and insulin growth factor-1 expression in the infarcted heart. Epicardial implantation of a fibroblasts/hiPSC-CMs patch electrically enhanced conduction, lowered left ventricular end-diastolic pressure, and improved diastolic function in rats with CHF. These changes were associated with increases in cytokine expression.

Two-dimensional speckle-tracking echocardiographic evaluation of the longitudinal deformation of the left ventricular myocardium in patients with severe coronary artery tortuosity.

Coronary artery tortuosity (CAT) is an anatomical condition in which epicardial coronary arteries have abnormal curves or spiral courses. Although correlated with higher rates of positive stress test, its effects on the myocardial function remain to be clearly defined. We included in this cross-sectional study and evaluated with 2D speckle-tracking echocardiography 40 consecutive patients admitted to our hospital for selective coronary angiography which showed severe CAT without significant epicardial coronary artery stenosis, and 40 consecutive subjects matched for age, hypertension, and diabetes in whom selective coronary angiography showed neither CAT nor significant epicardial coronary artery stenosis. Systolic strain, strain rate, and early and late diastolic strain rates were not significantly different between the 2 groups, even after adjustment for potential confounding variables. The 2D speckle-tracking echocardiography-derived indices of longitudinal deformation of the left ventricular myocardium were not significantly different between the patients with severe CAT and controls.

Effect of Coronary Slow Flow on the Longitudinal Left Ventricular Function Assessed by 2-Dimensional Speckle-Tracking Echocardiography.

The coronary slow flow phenomenon is defined as the slow progression of an angiographic contrast agent to the distal part of the coronary arteries on selective coronary angiography in the absence of stenosis. There are some studies with different results about the effect of this phenomenon on left ventricular (LV) function. The aim of our study was to evaluate the longitudinal LV function in the coronary slow flow phenomenon using 2-dimensional (2D) speckle-tracking echocardiography. In a study with a patient-to-patient matched design, 36 patients with the coronary slow flow phenomenon and 36 individuals with normal coronary flow matched for age (±5 years), sex, hypertension, and diabetes mellitus were compared in terms of the longitudinal LV systolic and diastolic functions by pulsed wave tissue Doppler echocardiography and 2D speckle-tracking echocardiography-derived indices. Lateral s' and e' waves were lower in the patients with the coronary slow flow phenomenon, but there were no statistically significant differences between the groups regarding the other tissue Doppler echocardiographic indices and longitudinal systolic strain and systolic and diastolic strain rates derived by 2D speckle-tracking echocardiography. Our results showed that the coronary slow flow phenomenon could not impair the longitudinal LV systolic and diastolic functions.

Abstract 13501: Measures of Three-dimensional Left Ventricular Mechanics Deteriorate Acutely After Cardiotoxic Cancer Therapy

Background: Doxorubicin and trastuzumab are commonly used breast cancer therapies with established cardiotoxic effects. However, the changes in myocardial mechanics with cancer therapy cardiotoxicity remain poorly defined, and noninvasive measures are needed to identify patients at increased risk. Our objective was to define the acute changes in three-dimensional (3D) echocardiography-derived indices of cardiac mechanics in patients receiving these therapies. Methods: In a prospective, longitudinal cohort of women with breast cancer receiving doxorubicin and/or trastuzumab, we obtained 3D echocardiography images before therapy (baseline) and during therapy at 3 months and 1 year of follow-up. Images were acquired at a minimum of 22 frames per second and analyzed by two readers using a vendor-independent analysis platform (TomTec Cardiac Performance Analyses, Unterschleissheim, Germany). Left ventricular twist, torsion, and principal strain were quantitated semi-automatically using 3D speckle tracking imaging. Standard descriptive statistics were used to summarize these measures over time. Results: Eighty-seven patients (mean age at baseline 49 years, 65% Caucasian) contributed at least 1 observation to the analysis. At baseline, median twist was 10.96° (interquartile range [IQR] 6.64, 13.59), torsion was 1.41°/cm (IQR 0.86, 1.70), and principal strain was -30.40% (-33.64, -28.55). At 3 months and 1 year, there were consistent declines in twist, torsion, and principal strain as displayed in Table I. Conclusions: In a prospective cohort of women with breast cancer receiving doxorubicin and/or trastuzumab, left ventricular twist, torsion, and principal strain declined over the first year of therapy. Ongoing research is focused on determining the clinical significance of these changes over time. Table 1. Longitudinal changes in 3D twist, torsion, and principal strain; summaries presented as median (interquartile range).

THE EFFECT OF POSTNATAL TRANSITIONAL CIRCULATION ON ECHOCARDIOGRAPHY-DERIVED INDICES OF HEART FUNCTION IN HEALTHY NEONATES

Novel echocardiography-derived indices (EDIs) of cardiac function are beginning to be utilized for studying the myocardial function in newborn infants. Several of these indices have been shown to be dependent on loading conditions. Immediate postnatal period in normal neonates is characterized by dramatic physiological hemodynamic changes, most notably reduction in right ventricular (RV) afterload and increase in left ventricular (LV) afterload. Before these EDIs are used in neonates suffering from pathological alternations in postnatal transition, it is important to understand whether physiologically normal changes associated with postnatal transition have any major influence on them. In this study, we sequentially measured conventional and novel indices of left and right ventricular systolic and diastolic function in a cohort of healthy neonates starting shortly after birth till end of 1st day of life, thus covering the period of peak changes transitional circulation. Antenatal consent was obtained from 15 pregnant women who presented to our maternity ward in labor at term gestation after having had an uncomplicated low risk singleton pregnancy. All infants but 1 infant was delivered vaginally. 3 infants had to be excluded - 1 was diagnosed with delay in transition shortly after birth, 1 was unexpectedly found to be large for gestational age and the mother of another infant developed acute postpartum hemorrhage. Remaining 12 well term neonates (mean wt. 3.49±0.53Kg) underwent 4 sequential echocardiograms at <0.5, 2.5, 8 and 22 hours of life. Images were collected using 2-D, color Doppler and tissue Doppler imaging and various EDIs of systolic [RV-S', TAPSE, LV-S’, LV ejection fraction (LVEF), LV speckle-tracking derived global longitudinal strain (LVGLS)], diastolic [E:A, E':A', E:E' (for each ventricle)], and global ventricular performance [MPI'] were measured. Pulmonary artery acceleration time (PAAT) was measured as a surrogate of pulmonary vascular resistance. Changes over time were analyzed using 1-way repeat measures ANOVA. In spite of significant changes in HR and PAAT over the study period, all systolic EDIs for both ventricles remained unchanged over time. Both S' velocities showed weak but significant linear correlation with HR. Among EDIs for diastolic function, E:E' was the only marker which remained unchanged for both ventricles throughout the study period (TABLE). We identified that in healthy newborns, RV-TAPSE, LVEF, LVGLS and E:E' were least affected by physiological alterations in HR and transitional circulation, and hence may be more suitable for use in disorders of postnatal transition.

Accuracy of Doppler-Derived Indices in Predicting Pulmonary Vascular Resistance in Children With Pulmonary Hypertension Secondary to Congenital Heart Disease With Left-to-Right Shunting

This study aimed to evaluate the accuracy of Doppler echocardiography-derived indices in children with pulmonary hypertension secondary to congenital heart disease with left-to-right shunting. Doppler-derived indices including the acceleration time corrected (AcTc), deceleration time corrected, deceleration index, peak velocity, heart-rate-corrected inflection time (InTc), and a new index (the acceleration slope [Acc = peak flow velocity/AcTc]) were measured from the pulmonary artery (PA) systolic flow curve before and after 100 % oxygen administration in the main, left, and right PAs of 33 children. The acquired data were compared between low and high pulmonary vascular resistance (PVR) groups and between responders and nonresponders to the vasoreactivity test. The AcTc values differed significantly between the low and high PVR groups before and after oxygen administration in the main (P = 0.032 and <0.001, respectively), right (P = 0.011 and <0.001, respectively), and left (P < 0.001 and <0.001, respectively) PAs. The AcTc cutoff point in the main PA was 3.44 before oxygen administration (81% sensitivity and 91% specificity). The InTc in the main PA and its changes differed significantly between the low and high PVR groups before and after oxygen administration and between the responders and nonresponders (P = 0.016, 0.046, and 0.021, respectively). The velocity changes of the PA in the main PA differed significantly between the responders and nonresponders to oxygen administration (P < 0.001). The Acc and its changes differed significantly between the low and high PVR groups after oxygen administration and between the responders and nonresponders to oxygen administration (P = 0.044 and 0.006, respectively). Doppler echocardiographic examination using PA systolic flow indices in addition to PA reactivity testing is a promising technique for assessing PVR in children with congenital heart disease.

Adrenal Function in Preterm Infants Undergoing Patent Ductus Arteriosus Ligation

Background: Targeted milrinone treatment for low left ventricular output (LVO) reduces the incidence of acute cardiorespiratory instability following ligation of patent ductus arteriosus (PDA) in preterm infants. Despite this, some infants continue to experience postoperative deterioration. Adrenal insufficiency related to prematurity has been postulated as a possible mechanism. Objectives: To describe adrenal function in premature infants undergoing PDA ligation and to investigate its association with pre- and postoperative clinical and echocardiography-derived indices of disease severity. Methods: A retrospective cohort study was conducted over a 2-year period on infants who underwent PDA ligation and had preoperative adrenocorticotropic hormone (ACTH) stimulation. All infants were screened by echocardiography for low LVO at 1 h after surgery and treated with intravenous milrinone if LVO <200 ml/kg/min. The primary outcome evaluated was low LVO at 1 h after surgery. Secondary outcomes included hypotension and oxygenation and ventilation failure occurring within 24 h. Results: A total of 35 infants at a median gestation of 25.4 (24.5-26.4) weeks and weight at birth of 700 (600-810) g were included. Baseline median cortisol measured preoperatively was 202 (137-403) nmol/l. Following the ACTH stimulation test, 3 infants had cortisol ≤500 nmol/l while 15 had ≤750 nmol/l. There was no association seen between any cortisol value and low LVO postoperatively. Post-ACTH cortisol ≤750 nmol/l was significantly associated with hypotension (p = 0.03) and oxygenation (p = 0.04) and ventilation (p = 0.008) failure. Receiver-operator characteristic curve showed a high predictive value of post-ACTH cortisol for all clinical outcomes. Conclusions: Post-ACTH cortisol (≤750 nmol/l) may be associated with clinical indices of postoperative cardiorespiratory instability. Relative adrenal insufficiency may play a role in the etiology of post-PDA ligation hemodynamic and respiratory instability.

Successful transcatheter aortic valve implantation (TAVI) is associated with transient left ventricular dysfunction

ObjectiveTo investigate early haemodynamic changes after transfemoral transcatheter aortic valve implantation (TAVI) and the relationship with myocardial injury and neurohormonal activation.DesignSingle-centre prospective observational study.SettingTertiary cardiac centre.Patients42 patients undergoing transfemoral TAVI...

Accuracy of Doppler-Derived Estimation of Pulmonary Vascular Resistance in Congenital Heart Disease: An Index of Operability

Pulmonary vascular resistance (PVR) is a critical and essential parameter during the assessment and selection of modality of treatment in patients with congenital heart disease (CHD) accompanied by pulmonary arterial hypertension (PAH). Cardiac catheterization is the "gold standard" but is an invasive method for PVR measurement. A noninvasive and reliable method for estimation of PVR in children has been a major challenge and most desirable during past decades, especially for those who need repeated measurements. In a prospective study and among consecutive patients who were referred for cardiac catheterizations, PVR was calculated as the ratio of the transpulmonary pressure gradient (∆P) to the amount of the pulmonary flow (QP) accordingly for 20 patients with CHD and high PAH. Subsequently and noninvasively, PVR was assessed for these patients by a Doppler echocardiography-derived index defined as the ratio of the tricuspid regurgitation velocity (TRV(m/s)) to the velocity time integral (VTI(cm)) of the right-ventricular outflow tract (RVOT). There was a good correlation between PVR measured at catheterization (PVR(cath)) and TRV/VTI(m) ratio; the mean of three measurements of VTI (VTI(m)) with R (2) = 0.53 (p = 0.008). In addition, a TRV/VTI(m) value of 0.2 provided a sensitivity of 71.4% and a specificity of 100% for PVR >6 Woods units (WU) as well as sensitivity of 90% and specificity of 90% for a PVR equal to 8 WU. PVR value between 6 and 8 WU by catheterization has been considered as a cut-off point for intervention in children with left-to-right shunts and PAH. In conclusion, Doppler-derived TRV/VTI(m) ratio is a reliable index that may be helpful as a supplementary diagnostic tool for the selection of modality of treatment and follow-up of patients with PAH and increased PVR.

Palpography Detects Mechanical Dyssynchrony and Worsens with Right Ventricular Pacing and Reduced Left Ventricular Ejection Fraction

QRS width and echocardiography-derived indices are limited predictors of response to resynchronization therapy. We applied digital palpography, using vibration resonance imaging, to investigate the effects of right ventricular pacing and left ventricular ejection fraction (LVEF) on mechanical and electrical dyssynchrony. Forty-nine subjects were examined: 24 normal controls, 18 subjects with right ventricular apical pacing (12 with reduced LVEF), and seven subjects with reduced LVEF and narrow QRS. Digital measurement of QRS width was performed. Electric dyssynchrony index (EDI) was measured as the time interval between peak R-waves of the same QRS complex of simultaneously recorded standard limb electrocardiograms, L1 and L2. A matrix of 6 × 6 vibration recording transducers was applied to chest. The interval between the onset of Q-wave and the peak of amplitude vibration for each transducer was measured, and a three-dimensional map for the whole matrix of transducers was generated. Median values (QE1) were measured. Mechanical vibration systolic dyssynchrony index (VSDI) for each subject was determined as the standard deviation of the difference between the median value and each transducer interval. EDI was larger in subjects with right ventricular pacing. Mechanical dyssynchrony indices were larger with pacing and reduced LVEF. EDI correlated with QRS width (r(2) = 0.7), with VSDI (r(2) = 0.42), and with QE1 (r(2) = 0.74). QRS width correlated with QE1 (r(2) = 0.75). Digital chest palpography can determine dyssynchrony indices that are larger in subjects with right ventricular pacing and reduced LVEF and correlate with parameters of electrical dyssynchrony.

Myocardial performance index during rapidly changing loading conditions

The myocardial performance index is a non-geometric, heart rate-independent echocardiography-derived index of left ventricular performance combining systolic and diastolic function. There is an ongoing debate whether the myocardial performance index is affected by preload or not. Moreover, a systematic evaluation of the effect of changing tidal volume ventilation on the myocardial performance index is still lacking. The aim of our study was to assess whether acute changes in preload and/or different depth of tidal volume ventilation affect the myocardial performance index. In all, 14 anesthetized pigs (35 +/- 2 kg) were studied during changing tidal volumes (VT 5, 10 and 15 mL kg(-1)) at baseline, after removal of 500 cm(3) of blood (haemorrhage) and after retransfusion of shed blood plus additional 500 cm(3) 6% hydroxyethyl starch (fluid loading). Echocardiographic measurements at each experimental stage included myocardial performance index, left ventricular end-diastolic area and fractional area change. Central venous pressure, pulmonary capillary wedge pressure, cardiac output and stroke volume index were obtained by a pulmonary artery catheter. Global end-diastolic volume was obtained by transpulmonary thermodilution. Comparing different loading conditions, we found significant changes in cardiac output, stroke volume index, central venous pressure, pulmonary capillary wedge pressure, global end diastolic volume and left ventricular end-diastolic area, indicating clinically relevant changes in preload. In the haemorrhage group, there was a significant reduction in the myocardial performance index (P < 0.05) independent of tidal volume applied and this was reversed after fluid loading. However, myocardial performance index was significantly impaired (P < 0.05) by high tidal volume ventilation (15 mL kg(-1)), while tidal volumes of 5 and 10 mL kg(-1) had no effect. The myocardial performance index is largely dependent on changes in preload. Moreover, high tidal volume ventilation significantly impaired the myocardial performance index.

Impact of beating heart left atrial ablation on left-sided heart mechanics

The cut-and-sew Cox-Maze procedure is the gold standard for surgical treatment of atrial fibrillation, but it is associated with long-term impairment of left atrial mechanical function. We developed a bipolar, irrigated radiofrequency ablation device. We hypothesized that beating heart radiofrequency left atrial ablation would result in minimal acute changes in left atrial hemodynamics. Six healthy subjects were studied. Combination pressure-conductance catheters were inserted into the left atrium and ventricle. With the use of the device, atrial ablation was performed on the beating heart without cardiopulmonary bypass, including electrical isolation of the posterior left atrium and atrial appendage myocardium. Simultaneous left-sided heart pressure-volume and intracardiac echocardiography data were acquired before ablation, after left atrial appendage ablation alone, and after all ablation (with and without appendage occlusion). The derived indices of left-sided heart mechanical function were examined. Relative to baseline, no significant diminishment in pressure-volume or intracardiac echocardiography-derived indices of global left-sided heart mechanical function were observed after ablation, with or without appendage occlusion. Mitral valve morphology and function were not significantly altered. A significant diminishment of atrial appendage systolic flow was noted after appendage ablation in association with spontaneous echocardiographic contrast in this region. In this model, ablation does not seem to compromise global left-sided heart mechanical function. However, these findings mask regional diminishment in atrial appendage systolic function. This observation demonstrates that electrical isolation of the appendage should be accompanied by its occlusion or excision. Appendage occlusion after ablation does not seem to compromise left-sided heart mechanical function.

Disruption of the ventricular myocardial force-frequency relationship after cardiac surgery in children: Noninvasive assessment by means of tissue Doppler imaging

Impaired ventricular function after cardiopulmonary bypass and surgical repair remains a commonly encountered clinical problem. We hypothesized that the well-described impairment of calcium cycling after cardiac surgery would significantly affect the ventricular myocardial force-frequency relationship, which can be measured noninvasively by using the tissue Doppler echocardiography-derived index of contractility isovolumic acceleration. Children undergoing repair of congenital heart defects were studied. Rate-related changes in contractility were measured by means of simultaneous atrial pacing and tissue Doppler echocardiography preoperatively and postoperatively. Although closure of atrial septal defect did not affect ventricular myocardial systolic performance, closure of ventricular septal defect lead to a marked postoperative decrease of basal contractile force (2.0 +/- 0.7 m/s2 preoperatively vs 1.0 +/- 0.7 m/s2 postoperatively, P < .02). Furthermore, the force-frequency relationship curves were significantly different (P < .001), with a reduced force-rate trajectory, and also peak force was attained. Neonates undergoing the arterial switch procedure showed the most marked postoperative decrease of isovolumic acceleration at basal heart rates and force-frequency relationship with reduced trajectory and peak force development (P < .0001). This is the first clinical study describing the noninvasive acquisition of ventricular force-frequency relationships in children undergoing operations for congenital heart disease. There is a marked variability in response, ranging from no effect in patients undergoing atrial septal defect closure to a profound reduction in myocardial contractile responses after neonatal arterial switch. This simple noninvasive method allows measurement of a hitherto rarely examined property of the myocardium, an understanding of which might allow refinement of myocardial protection and postoperative myocardial support.

Doppler Echocardiography-Derived Index of Myocardial Performance (TEI Index)

Plasma brain natriuretic peptide (BNP) has diagnostic and prognostic value in heart failure. Cardiac dysfunction varies from systolic or diastolic dysfunction alone to the combination of both. In the present study, Doppler echocardiographic parameters, including the Doppler echocardiography-derived index (TEI index), were compared with plasma BNP levels in 74 patients with various heart diseases. Blood sampling was performed before an echocardiographic examination was conducted. The TEI index was defined as the summation of isovolumic contraction and relaxation time divided by ejection time. In patients with left ventricular (LV) systolic dysfunction (ejection fraction <50%), the TEI index and BNP were increased significantly compared with patients with normal LV systolic function (p<0.05). Patients with a TEI index > or =0.45 showed significantly increased BNP levels compared with patients with a TEI index <0.45, irrespective of LV systolic function (241.4+/-451.2 vs 65.9+/-81.8pg/ml; p<0.05). The TEI index was significantly higher in patients with a BNP > or =73pg/ml than in patients with BNP <73pg/ml (0.57+/-0.24 vs 0.46+/-0.17; p<0.05). Other echocardiographic parameters did not correlate significantly with levels of plasma BNP. Of the echocardiographic parameters, a simple Doppler index (TEI index) that combines systolic and diastolic function can detect LV dysfunction in patients with high levels of plasma BNP in various heart diseases.