The Doppler-Derived Myocardial Performance Index Is Determined by Both Left Ventricular Systolic and Diastolic Function as Well as by Afterload and Left Ventricular Mass

Echocardiographic Features of Cardiac Involvement in Myotonic Dystrophy 1: Prevalence and Prognostic Value

Myotonic dystrophy type 1 (DM1) is the most common muscular dystrophy in adults. Cardiac involvement is reported in 80% of cases and includes conduction disturbances, arrhythmias, subclinical diastolic and systolic dysfunction in the early stage of the disease; in contrast, severe ventricular systolic dysfunction occurs in the late stage of the disease. Echocardiography is recommended at the time of diagnosis with periodic revaluation in DM1 patients, regardless of the presence or absence of symptoms. Data regarding the echocardiographic findings in DM1 patients are few and conflicting. This narrative review aimed to describe the echocardiographic features of DM1 patients and their prognostic role as predictors of cardiac arrhythmias and sudden death.

Cardiac Imaging in Liver Transplantation Candidates: Current Knowledge and Future Perspectives

Cardiovascular dysfunction in cirrhotic patients is a recognized clinical entity commonly referred to as cirrhotic cardiomyopathy. Systematic inflammation, autonomic dysfunction, and activation of vasodilatory factors lead to hyperdynamic circulation with high cardiac output and low peripheral vascular resistance. Counter acting mechanisms as well as direct effects on cardiac cells led to systolic or diastolic dysfunction and electromechanical abnormalities, which are usually masked at rest but exposed at stress situations. While cardiovascular complications and mortality are common in patients undergoing liver transplantation, they cannot be adequately predicted by conventional cardiac examination including transthoracic echocardiography. Newer echocardiography indices and other imaging modalities such as cardiac magnetic resonance have shown increased diagnostic accuracy with predictive implications in cardiovascular diseases. The scope of this review was to describe the role of cardiac imaging in the preoperative assessment of liver transplantation candidates with comprehensive analysis of the future perspectives anticipated by the use of newer echocardiography indices and cardiac magnetic resonance applications.

Myocardial performance index in female athletes

BACKGROUND

Long-term intensive training leads to morphological and mechanical changes in the heart generally known as "athlete's heart". Previous studies have suggested that the diastolic and systolic function of the ventricles is unaltered in athletes compared to sedentary. The purpose of this study was to investigate myocardial performance index (MPI) by pulsed wave Doppler (PWD) and by tissue Doppler imaging (TDI) in female elite athletes compared to sedentary controls.

METHODS

The study consisted of 32 athletes (mean age 20 ± 2 years) and 34 sedentary controls (mean age 23 ± 2 years). MPI by PWD and TDI were measured in the left (LV) and right ventricle (RV) in both groups. Moreover, comparisons of MPI by the two methods and between the LV and RV within the two groups were made.

RESULTS

There were no significant differences in MPI between athletes and controls (p > 0.05), whereas the LV had significantly higher MPI compared to RV (p < 0.001, in athletes and controls). The agreement and the correlation between the two methods measuring MPI showed low agreement and no correlation (athletes RV r = -0.027, LV r = 0.12; controls RV r = 0.20, LV r = 0.30).

CONCLUSION

The global function of the LV and RV measured by MPI with PWD and TDI is similar in female athletes compared to sedentary controls. Conversely, both MPI by PWD and by TDI shows a significant difference between the LV and RV. However, the agreement and correlation between conventional methods of measuring MPI by PWD compared to MPI by TDI is very poor in both these populations.

Left ventricular remodeling and diastolic function in chronic hypertensive pregnant women

Hypertension during pregnancy is a problem that impacts maternal morbidity and mortality. Dyspnea and edema are common symptoms, often secondary to physiological changes, but may raise doubts as to ventricular dysfunction.

OBJECTIVE

To evaluate the ventricular geometry pattern and diastolic function in chronic hypertensive pregnant women (HPW).

METHODS

Prospective, cross-sectional study on 62 pregnant women over a 29-month period, from March 2009 to July 2011, in Brazil was done. Thirty-one HPWs and 31 normotensive pregnant women (NPW) underwent clinical and cardiovascular evaluations, and were subjected to transthoracic echocardiogram.

RESULTS

LV mass (HPW: 220.9 ± 43.3 vs. NPW: 192.9 ± 39.8 g, p = 0.01), posterior wall thickness (HPW: 9.9 ± 1.1 vs. NPW: 9.2 ± 0.9 mm, p = 0.005), mitral flow A wave velocity (HPW: 0.60 ± 0.16 vs. NPW: 0.52 ± 0.10 m/s, p = 0.02), tissue Doppler A' wave velocity (HPW: 10 ± 2 vs. NPW: 8.9 ± 1cm/s, p=0.02), and E/E' ratio (HPW: 6.8 ± 2.2 vs. NPW: 5.5 ± 1.6, p = 0.01) were higher in HPWs. Septal and lateral walls E' wave velocities (HPW: 13 ± 2 vs. NPW: 15 ± 3 cm/s, p=0.001), and E'/A' ratio (HPW: 1.26 ± 0.38 vs. NPW: 1.77 ± 0.49, p = 0.00003) were lower in HPWs. There was a positive linear correlation between body mass index (BMI) and ventricular mass, A wave, systolic, diastolic blood pressures, and a negative correlation between BMI, E' wave and E'/A' ratio.

CONCLUSION

Ventricular remodeling showed a direct relationship with body weight, and both groups showed a predominant pattern of eccentric ventricular hypertrophy. The LV diastolic function was abnormal in HPWs.

Asymptomatic right ventricular dysfunction in surgically repaired adult tetralogy of fallot patients

Background:

Right ventricular (RV) dysfunction after surgical repair of Tetralogy of Fallot (TOF) is often asymptomatic and may be detected by tissue Doppler imaging (TDI). The severity of RV dysfunction is more after intracardiac repair with transannular patch (TAP).

Methods:

One hundred seventy-three adult patients who have undergone surgical repair for TOF were prospectively analyzed for RV function using 2D echocardiography and TDI. RV function was compared between patients who have undergone intracardiac repair with and without TAP.

Results:

In both the patient sub-groups, TDI derived myocardial performance index (MPI) and myocardial velocities were abnormal even when 2D echocardiography derived RV functional area change was normal. TDI derived MPI was significantly higher (0.5 ± 0.1 vs. 0.4 ± 0 P < 0.001) and Systolic tricuspid annular velocity (Sa) (9.2 ± 1.3 vs. 10.8 ± 1.6 P < 0.001) was significantly lower in the TAP group. Older age at surgery and severity of pulmonary regurgitation on follow-up were among the significant predictors of TDI derived MPI.

Conclusions:

Asymptomatic RV dysfunction in surgically repaired adult TOF atients can be detected by TDI. Extent of RV dysfunction was significantly greater with patients requiring TAP, in those operated at older age, and in patients with severe pulmonary regurgitation.

Myocardial performance index derived from preejection period: a novel and feasible parameter in evaluation of cardiac performance in patients with permanent atrial fibrillation

BACKGROUND

Using tissue Doppler echocardiography, we can measure preejection period (PEPa), defined as the interval measured from the onset of QRS to the onset of the systolic mitral annular velocity pattern, isovolumic relaxation time (IVRTa), defined as the interval measured from the end of systolic mitral annular velocity pattern to the onset of diastolic mitral annular velocity pattern, and ejection time (ETa), defined as the interval measured from the onset to the end of systolic mitral annular velocity pattern on the same cardiac cycle. The aim of this study is to test the applicability of PEPa-derived myocardial performance index (MPI), defined as the ratio of PEPa + IVRTa to ETa, as an indicator of combined left ventricular systolic and diastolic function in patients with permanent atrial fibrillation.

METHODS

Echocardiographic examination was performed in 54 consecutive patients with permanent atrial fibrillation. Clinical and echocardiographic parameters were compared and analyzed.

RESULTS

After a multivariate analysis, the average RR interval on the tissue Doppler image (β=-0.328, P = 0.002), left ventricular ejection fraction (β=-0.260, P = 0.024), and early diastolic mitral annular velocity (β=-0.408, P < 0.001) were the major determinants of PEPa-derived MPI.

CONCLUSIONS

PEPa-derived MPI had a significant correlation with echocardiographic left ventricular diastolic and systolic function. It may be a novel and feasible indicator in assessment of global left ventricular function in patients with permanent atrial fibrillation.

Usefulness of the myocardial performance index determined by tissue Doppler imaging m-mode for predicting mortality in the general population

The objective of this study was to evaluate the prognostic value of the myocardial performance index (MPI), assessed by color-coded tissue Doppler imaging (TDI) M-mode through the anterior mitral leaflet. Color TDI M-mode through the mitral leaflet is an easy, very fast, and precise method to estimate cardiac intervals and thus obtain the MPI, but the diagnostic and prognostic values of this parameter are unknown. In a large population study, cardiac function was evaluated in 1,100 participants by conventional echocardiography and TDI. MPI was calculated from pulse-wave Doppler analyses of left ventricular in- and outflow using standard procedures (MPI(conv)) and by color-coded TDI M-mode through the mitral leaflet in the apical 4-chamber view (MPI(TDI)). MPI(TDI) was increased in subjects with coronary heart disease (CHD) compared to controls, even after multivariable adjustment (p <0.002). During follow-up (median 5.3 years), 90 participants died. MPI(TDI) was significantly associated with overall mortality, and risk of dying increased by 31% per 0.1 increase in MPI(TDI). In contrast to MPI(conv), MPI(TDI) provided independent prognostic information in a multivariable Cox proportional hazard model (adjusting for age, gender, body mass index, heart rate, mean arterial blood pressure, and CHD), with a hazard ratio of 1.18 (p = 0.01) per 0.1 increase in MPI(TDI). In conclusion, MPI(TDI) is a quick, simple, and reproducible measurement, which is increased in subjects with CHD and provides independent prognostic information in a low-risk population.

Myocardial performance index suggests optimal fluid loss during hemodialysis

BACKGROUND

Patients on long-term maintenance hemodialysis (HD) are at high risk of developing cardiovascular disease and suffering various cardiovascular complications during HD.

HYPOTHESIS

The purpose of this study was to evaluate the influence of changing loading conditions on the myocardial performance index (MPI) in patients on long-term HD and to specify an optimal level of fluid loss during HD that would maintain stable global cardiac function.

METHODS

The study consisted of 52 patients with end-stage renal failure (ESRF), mean age 56±11.7 y, range: 25-80 y, on regular HD. For each patient a complete echocardiographic-Doppler examination was performed before and after HD. Systolic and diastolic parameters of left ventricular function were measured, and the myocardial performance index (MPI) was calculated.

RESULTS

The MPI was significantly prolonged after HD (0.47±0.15 before HD versus 0.59±0.16 after HD, p < 0.001). Mean change in body weight during HD was 2.1±0.86 kg. The MPI did not change significantly in patients with intradialytic weight loss up to 1.75 kg.

CONCLUSIONS

The MPI value seems to be independent of acute preload changes only when fluid loss is less than 1.75 kg. A 1.75-kg fluid loss during HD seems to be the optimal goal. In ESRF patients on HD, the MPI seems to be a good indicator of global left ventricular function and potentially a valuable aid in the effort to maintain optimal fluid balance.

Myocardial performance index derived from brachial-ankle pulse wave velocity: a novel and feasible parameter in evaluation of cardiac performance

BACKGROUND

Right brachial pre-ejection period (rbPEP), brachial-ankle pulse wave velocity (baPWV), and right brachial ejection time (rbET) can be automatically determined from an ABI-form device. The aims of this study are to test the applicability of baPWV-derived myocardial performance index (MPI) (defined as the ratio of rbPEP divided by its own s.d. + baPWV divided by its own s.d. to rbET divided by its own s.d.) as an indicator of combined left ventricular (LV) systolic and diastolic functions.

METHODS

A sum of 215 patients were consecutively included. The rbPEP, baPWV, and rbET were measured using an ABI-form device and LV function was determined by echocardiography.

RESULTS

After a multivariate analysis, diastolic blood pressure (beta = 0.220, P < 0.001), LV ejection fraction (LVEF) (beta = -0.291, P < 0.001), transmitral E wave velocity (E) (beta = -0.106, P = 0.032), early diastolic mitral annular velocity (Ea) (beta = -0.142, P = 0.009), and ET obtained by tissue Doppler echocardiography (beta = -0.397, P < 0.001) were the major determinants of baPWV-derived MPI. The area under the curve for rbPEP, baPWV, rbET, rbPEP/rbET, and baPWV-derived MPI in prediction of Ea <8 cm/s, E/Ea >10, or LVEF <50% were 0.69, 0.76, 0.67, 0.73, and 0.83, respectively.

CONCLUSIONS

BaPWV-derived MPI had a significant correlation with echocardiographic LV diastolic and systolic function. It may be a novel and feasible indicator in assessment of global LV function.

Tei index correlates with tissue Doppler parameters and reflects neurohormonal activation in patients with an abnormal transmitral flow pattern

BACKGROUND

Tei index (TI) is a Doppler parameter which reflects combined systolic and diastolic function. We aimed to study the relationship between TI, both traditional and tissue Doppler imaging (TDI) echocardiographic parameters and neurohormonal profile in outpatients with diastolic dysfunction expressed by an abnormal transmitral flow pattern.

METHODS AND RESULTS

A total of 67 consecutive outpatients with diastolic dysfunction (abnormal transmitral flow pattern) were studied; all patients underwent clinical evaluation, blood sampling for B-type natriuretic peptide (BNP) plasma assaying, echocardiography for the determination of left ventricular ejection fraction (LVEF), dP/dt, left atrium (LA) dimensions, longitudinal systolic (S) and diastolic wall velocities (E'and A'), TI measured with Doppler echocardiography, and mitral regurgitation (MR) quantified on a semicontinuous scale. TI values were significantly correlated with BNP levels (r = 0.33; P < 0.01), LVEF (r =-0.56; P < 0.001), dP/dt (r =-0.52; P < 0.01), S (r =-0.45; P < 0.001), E'(r =-0.36; P < 0.01), A'(r =-0.27; P < 0.05), LA volume (r = 0.35; P < 0.01), and MR (P for trend < 0.05). In a multivariate regression analysis, TI was an independent predictor of increased BNP levels (beta= 0.32; P < 0.05), even after correction for potential confounders. ROC analysis showed as values of TI >0.59 identified subjects with combined systolic and diastolic dysfunction with a sensitivity of 73.8% and a specificity of 71.4%.

CONCLUSIONS

In outpatients with diastolic dysfunction, TI, an easy to perform parameter for global ventricular performance assessment, might be useful in identifying subjects with concomitant systolic impairment and neurohormonal activation.

Doppler-derived myocardial performance index in patients with impaired left ventricular relaxation and preserved systolic function

BACKGROUND

The Doppler-derived myocardial performance index (MPI) has been used in the evaluation of left ventricular (LV) function in several diseases. In patients with isolated diastolic dysfunction, the diagnostic utility of this index remains unclear. The aim of this study was to determine the diagnostic utility of MPI in patients with systemic hypertension, impaired LV relaxation, and normal ejection fraction.

METHODS

Thirty hypertensive patients with impaired LV relaxation were compared to 30 control subjects. MPI and its components, isovolumetric relaxation time (IRT), isovolumetric contraction time (ICT), and the ejection time (ET), were measured from LV outflow and mitral inflow Doppler velocity profiles.

RESULTS

MPI was higher in patients than in control subjects (0.45 +/- 0.13 vs 0.37 +/- 0.07 P < 0.0029). The increase in MPI was due to the prolongation of IRT without significant change of ICT and ET. MPI cutoff value of > or =0.40 identified impaired LV relaxation with a sensitivity of 63% and specificity of 70% while an IRT >94 ms had a sensitivity of 67% and specificity of 80%. Multivariate analysis identified relative wall thickness, mitral early filling wave velocity (E), and systolic myocardial velocity (Sm) as independent predictors of MPI in patients with hypertension.

CONCLUSIONS

MPI was increase in patients with hypertension, diastolic dysfunction, and normal ejection fraction but was not superior to IRT to detect impaired LV relaxation.

Myocardial performance index is a predictor of outcome after abdominal aortic aneurysm repair

OBJECTIVE

Perioperative measurement of the myocardial performance index (MPI) with transesophageal echocardiography in patients undergoing elective abdominal aortic aneurysm repair and its association with outcome.

DESIGN

A prospective observational study.

SETTING

A tertiary care university hospital.

PARTICIPANTS

Patients undergoing elective abdominal aortic aneurysm repair.

INTERVENTION

Perioperative transesophageal echocardiography.

MEASUREMENTS

Fifty-one consecutive patients undergoing elective abdominal aortic aneurysm repair were enrolled in the study. The MPI was calculated by using pulse-wave Doppler from the midesophageal window and the deep transgastric position of the probe. In addition, diastolic function was measured as the slope of the transmitral flow propagation velocity, and ejection fraction was calculated as a measure of ventricular systolic function. Comparisons between subjects with uncomplicated versus adverse outcomes were made by using a Mann-Whitney U test. Comparison of the incidence of adverse outcome among subjects with normal and elevated MPIs was made by using a Fisher exact test. Statistical significance was set at p < 0.05.

RESULTS

It was possible to calculate MPI in all patients with transesophageal echocardiography perioperatively. Patients with adverse postoperative outcomes had an elevated MPI as compared with those without any adverse outcome (0.50 v 0.30, p < 0.001). Also, an MPI of > or = 0.36 was associated with a statistically significant higher incidence of complications (congestive heart failure/prolonged intubation) (p < 0.001).

CONCLUSIONS

The MPI is an easily obtained echocardiographic measure of global ventricular performance, which can be measured perioperatively and may be useful as a prospective risk stratification index for patients undergoing elective abdominal aortic aneurysm surgery.

Xenon or propofol anaesthesia for patients at cardiovascular risk in non-cardiac surgery

BACKGROUND

The results of two European multi-centre trials on xenon anaesthesia led to the hypothesis that a xenon-based anaesthetic would keep left ventricular (LV) and circulatory function more stable than a propofol-based anaesthetic, in patients with coronary artery disease (CAD).

METHODS

In a prospective, randomized design, 40 patients of ASA classes III and IV with known CAD were anaesthetized for elective non-cardiac surgery with either xenon (n=20) or propofol (n=20), each combined with remifentanil. Target criteria were intraoperative LV function as evaluated by transoesophageal echocardiography (TOE: Tei index, circumferential fibre shortening), arterial pressure, and heart rate (HR).

RESULTS

Mean arterial pressure was decreased with propofol but was stable at pre-anaesthetic level with xenon (P<0.02) and HR was lower with xenon (P<0.01). The Tei index (also known as myocardial performance index) improved from 0.53 (0.14) to 0.45 (0.10) after 1 h with xenon and changed from 0.50 (0.14) to 0.55 (0.20) with propofol anaesthesia [means (SD); P=0.01 between the groups]. Deviation of circumferential fibre shortening from expected value after 1 h was -2 (14)% with xenon and -14 (18)% with propofol [means (SD); P=0.03]. There were no perioperative signs of acute myocardial ischaemia (TOE, ECG, and troponin T release).

CONCLUSIONS

Xenon anaesthesia provided a higher arterial pressure level than propofol, with no signs of cardiovascular compromise, in patients with CAD. Echocardiographic indices showed better LV function with xenon.

Effects of changes in loading conditions and heart rate on the myocardial performance index in cats

OBJECTIVE

To evaluate the effect of changes in hemodynamics on the myocardial performance index (MPI) in cats.

ANIMALS

6 mixed-breed cats.

PROCEDURES

Cats were anesthetized by administration of thiopental sodium; anesthesia was maintained by administration of isoflurane. Systolic arterial pressure and central venous pressure were measured by use of catheters, and heart rate was controlled by right atrial pacing. Afterload was increased by balloon occlusion of the descending aorta, and preload was increased by IV infusion of lactated Ringer's solution at a rate of 40 mL/kg/h. Echocardiography was performed for each condition.

RESULTS

Atrial pacing significantly increased heart rate. The MPI did not change with heart rate. Arterial pressure and MPI increased significantly during aortic occlusion. The IV infusion increased fractional shortening but did not change the MPI. Multiple regression analysis revealed that the MPI was not affected by heart rate, systolic arterial pressure, central venous pressure, fractional shortening, or velocity of the E wave.

CONCLUSIONS AND CLINICAL RELEVANCE

The MPI can be used to assess cardiac function in healthy cats. The MPI is independent of heart rate and systolic arterial pressure but is sensitive to changes in afterload.

Myocardial performance index during rapidly changing loading conditions: impact of different tidal ventilation

BACKGROUND AND OBJECTIVES

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.

METHODS

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.

RESULTS

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.

CONCLUSIONS

The myocardial performance index is largely dependent on changes in preload. Moreover, high tidal volume ventilation significantly impaired the myocardial performance index.

Utility of the myocardial performance index in a population with high prevalences of obesity, diabetes, and hypertension: the strong heart study

INTRODUCTION

The myocardial performance index (MPI) introduced by Tei, a Doppler-derived echocardiographic measure that reflects both left ventricular (LV) systolic and diastolic function, has been shown to have prognostic value in several clinical settings, including myocardial infarction and congestive heart failure. There are scant data on the correlates and prognostic value of MPI in a population without overt cardiovascular (CV) disease.

METHODS

We investigated clinical and physiologic correlates of MPI, as assessed from echocardiographic Doppler recordings in 1,862 American Indian participants free of coronary or valvular disease or LV systolic dysfunction in the population-based strong heart study (SHS). We then assessed the prognostic value of MPI for incident CV events, including nonfatal stroke, coronary heart disease, congestive heart failure, and CV death.

RESULTS

The study population was 59 +/- 8 years old (66% women); 48% had diabetes, 44% hypertension, and 54% were obese. In univariable analyses, MPI (mean = 0.24 +/- 0.17) showed significant negative associations with creatinine clearance, C-reactive protein (CRP), LV ejection fraction (EF), mitral valve E- and A-wave velocities, cardiac index (CI), stroke index (SI) and stroke index/pulse pressure (SI/PP), and significant positive associations with serum creatinine and total peripheral resistance index (TPRI) (all P < 0.05). There were no significant associations of MPI with hypertension or diabetes status, systolic or diastolic blood pressure, body mass index, hemoglobin A1C or LV mass. After adjusting for age, sex, diabetes, and hypertension, MPI remained weakly but significantly correlated with CRP, EF, CI, SI, SI/PP, mitral E- and A-wave velocities, and TPRI. MPI did not predict fatal and nonfatal CV events (risk ratio 1.06 per unit MPI, 95% C.I. 0.56-2.04; P = 0.85) at a mean follow-up of 7.1 +/- 2.2 years.

CONCLUSIONS

In a population-based sample of adults with high prevalence of diabetes, hypertension, and obesity but without overt CV disease, MPI has weak associations with clinical and physiologic determinants of cardiac function. Moreover, MPI does not provide prognostic information for CV events in this population. Though conceptually attractive as a global measure of cardiac function, MPI has limited utility in a high-risk population without clinical CV disease.

Effect of External Constraint on the Index of Myocardial Performance in a Canine Model of Left Ventricular Dysfunction

BACKGROUND

With left ventricular (LV) dysfunction, it is not clear how alterations in external constraint influence the index of myocardial performance (IMP). We have previously demonstrated that pericardial constraint is a factor in the production of the restrictive filling pattern. We hypothesized that altering pericardial constraint by changing intracardiac volume or removing the pericardium would produce similar directional changes in LV ejection time (LVET) and isovolumic relaxation time (IRT) resulting in minimal IMP changes.

METHODS

We studied 13 canines with chronic moderate LV dysfunction. LV pressures, transmitral and transaortic Doppler were obtained prior to and following pericardiectomy (PECT) with alterations of intracardiac volume, using inferior vena caval occlusion (IVCO) and volume loading.

RESULTS

With an intact pericardium, IVCO reduced LV size, LV end diastolic pressure (LVEDP), and increased deceleration time (all P < 0.05) but did not affect IMP. Volume loading increased LV size, LVEDP, and shortened deceleration time (all P < 0.05). LVET and IRT lengthened (P < 0.05), and IMP declined (0.58 +/- 0.24 to 0.52 +/- 0.13, P < 0.05). Following PECT, IVCO reduced LV volumes and LVEDP (P < 0.05), but did not change IMP. Volume loading increased LV size, stroke volume, and LVEDP (all P < 0.05). IMP declined (0.57 +/- 0.13 vs 0.51 +/- 0.14, P < 0.05) due to an increase in both LVET and IRT (P < 0.05). Comparison of stages prior to and following PECT revealed an increased LVET and stroke volume (P < 0.05) but a similar IMP.

CONCLUSION

Increases in intracardiac volume associated with elevated LVEDP resulted in reduced IMPs. Pericardiectomy increases LV volumes, stroke volume, and LVET but did not influence IMP.

Alteraciones ecocardiográficas asociadas al síndrome de apnea-hipopnea del sueño en función de su gravedad

INTRODUCTION AND OBJECTIVES

Sleep apnea-hypopnea syndrome (SAHS) is a prevalent condition that has well-known cardiovascular repercussions. However, few published echocardiographic studies have investigated the abnormalities present at SAHS diagnosis or their relationship with syndrome severity. Our objective was to evaluate myocardial structural, functional and performance parameters in these patients.

METHODS

In total, 110 consecutive patients diagnosed with SAHS between June 2005 and 2006 who required treatment with continuous positive airway pressure were divided into two groups according to SAHS severity. Baseline echocardiography was carried out to evaluate structural and functional variables. Findings in the two groups were compared by univariate and multivariate analysis.

RESULTS

The patients' mean age was 54 (13) years, their body mass index was 32 (6), 51% had comorbidities, and 74% were male. Patients with severe SAHS (i.e., apnea-hypopnea index [AHI] > or = 30) smoked and drank alcohol more and had larger neck circumferences. There was no significant difference in any structural parameter between the two groups. Functionally, patients with severe SAHS had shorter aortic (AHI<30 277 [4] ms vs AHIé30 263 [4] ms; P=.02) and pulmonary (AHI < 30 287 +/- 5 ms vs. AHI > or = 30 268 +/- 5 ms; P=.01) ejection times, and a higher Tei index (Left: AHI<30 0.51 [0.01] vs AHIé30 0.57 [0.02] [P=.04]; Right: AHI<30 0.38 [0.02] vs AHIé30 0.49 [0.03] [P=.02]). There were correlations between SAHS severity and the right Tei index, and aortic and pulmonary ejection times (P=.0001, P=.01, and P=.0001, respectively). The pulmonary ejection time was an independent predictor of SAHS severity (odds ratio: 0.98, 95% confidence interval, 0.97-0.99; P=.01).

CONCLUSIONS

Myocardial performance is poorer in patients with SAHS. The Tei index and ejection times are all associated with SAHS severity. The pulmonary ejection time is an independent predictor of disease severity.

Changes in the myocardial performance index during dobutamine administration in anesthetized cats

OBJECTIVE

To investigate the relationship between myocardial performance index (MPI; also known as the Tei index) and cardiac function in anesthetized cats administered dobutamine.

ANIMALS

6 adult cats.

PROCEDURES

Cats were anesthetized by administration of propofol (6 mg/kg, IV), and anesthesia was maintained by administration of isoflurane. Heart rate and systolic arterial pressure (SAP) were monitored. Stroke volume, cardiac output, and aortic blood flow (ABF) were measured by use of transesophageal ultrasonography. Left ventricular fractional shortening (LVFS), mitral E-wave velocity-to-A-wave velocity (E:A) ratio, and ejection time were measured by use of transthoracic echocardiography. Dobutamine was administrated via a cephalic vein at rates of 2.5, 5.0, and 10 microg/kg/min.

RESULTS

Heart rate, SAP, cardiac output, and ABF increased with dobutamine administration, whereas stroke volume significantly decreased. The LVFS significantly increased, and the E:A ratio significantly decreased. Total isovolumic time and the MPI significantly decreased. The MPI was negatively correlated (r=-0.63) with LVFS. Conversely, the MPI was positively correlated with the E:A ratio (r=0.47), stroke volume (r=0.66), and total isovolumic time (r=0.95). However, the MPI was not significantly correlated with heart rate, SAP, cardiac output, or ABF.

CONCLUSION AND CLINICAL RELEVANCE

Analysis suggested that the MPI provides a sensitive clinical assessment of cardiac response to medication in cats, which may be similar to the usefulness of the MPI reported in humans.

Differentiation of Left Ventricular Diastolic Dysfunction, Identification of Pseudonormal/Restrictive Mitral Inflow Pattern and Determination of Left Ventricular Filling Pressure by Tei Index Obtained from Tissue Doppler Echocardiography

BACKGROUND

Tei index obtained from tissue Doppler echocardiography (TDE-Tei index) has an inherent advantage of recording its systolic and diastolic components simultaneously on the same cardiac cycle. The aims of this study are to evaluate whether TDE-Tei index also exerts a correlation with left ventricular (LV) systolic and diastolic function and filling pressure and to see whether it can effectively identify the pseudonormal/restrictive mitral filling pattern.

METHODS

Echocardiographic examination was performed in 243 consecutive patients. These patients were classified into three groups as normal, abnormal relaxation, and pseudonormal/restrictive groups according to the transmitral E/A-wave velocity (E/A), early diastolic velocity of lateral mitral annulus (Ea) and E/Ea.

RESULTS

Standard Doppler indices of LV filling such as E, A, E/A, and E-wave deceleration time had a bimodal distribution, but Ea decreased and E/Ea and TDE-Tei index increased progressively with worsening of LV diastolic function. The sensitivity and specificity of TDE-Tei index>0.51 in the discrimination of pseudonormal/restrictive filling pattern were 85% and 96%, respectively. After stepwise multiple linear regression analysis, TDE-Tei index had a significant negative correlation with Ea (beta=-0.296, P<0.001) and ejection fraction (beta=-0.293, P<0.001) and positive correlation with E/Ea (beta=0.235, P=0.001).

CONCLUSIONS

TDE-Tei index increased with worsening of LV diastolic function and can effectively identify the pseudonormal/restrictive mitral inflow pattern. It also correlated with the echocardiographic parameters of LV systolic and diastolic function and filling pressure. It suggests that TDE-Tei index is a simple and feasible marker in assessing global LV function.

[Left ventricular electromechanical latency period is an additional indicator to upgrade from right to biventricular DDD pacing]

In DDD pacing, the left-ventricular electromechanical latency period defines the duration between premature ventricular stimulation and the prematurely ending left-atrial contribution to left-ventricular filling. It has to be considered in diastolic AV delay optimization. Individual duration of this parameter seemed to reflect the ventricular function. Therefore, we compared the left-ventricular electromechanical latency period due to right ventricular stimulus with the documented ejection fraction of two groups, 33 congestive heart failure patients carrying biventricular systems and 13 right ventricular paced bradycardia patients. A mean latency period of 168+/-26 ms was found in the heart failure patients (ejection fraction: 25+/-5%) which was significantly longer (p=0.0039) compared to the bradycardia patients (ejection fraction: 51+/-12%) with a mean latency of 119+/-13 ms. Thus, an increasing latency period during right ventricular DDD pacing therapy indicates decreasing ejection fraction. A cut-off interval of 135 ms allowed the discrimination of 93% of our patients as having an individual ejection fraction of either up to 35% or above. Thus, the left ventricular electromechanical latency period can be used as an additional parameter indicating the necessity to upgrade from right to biventricular DDD pacing.

Effects of modulation of left ventricular contractile state and loading conditions on tissue Doppler myocardial performance index

The Tei index is clinically useful to quantify left ventricular (LV) function, but it requires sequential Doppler recordings from two different views. A related myocardial performance index (MPI) using tissue Doppler (TD) can be rapidly calculated from a single beat; however, its ability to quantify contractility and the effects of acute changes in loading have not been determined. Our aim was to test the hypothesis that TD MPI can quantify contractile state but is affected by acute alterations in loading, using LV pressure-volume relations in an animal model. Eight dogs were studied by using mitral annular TD, high-fidelity pressure, and conductance catheters. TD MPI was calculated as (a' - b')/b', where a' was the duration of mitral annular velocity during diastole and b' was the duration of the systolic wave. End-systolic elastance (Ees), the time constant of isovolumic relaxation (tau), and peak positive and negative first derivative of pressure (dP/dtmax and dP/dtmin, respectively) were used as measures of LV function. Data were obtained at baseline, at dobutamine and esmolol infusion to alter contractile state, and at inferior vena cava and aortic occlusion to alter preload and afterload. TD MPI decreased from 0.83 (SD 0.19) to 0.62 (SD 0.20) with dobutamine and increased to 1.19 (SD 0.26) with esmolol. TD MPI significantly correlated with dP/dtmax (r = -0.76), Ees (r = -0.68), dP/dtmin (r = 0.82), and tau (r = 0.78); however, it was affected by acute decreases in preload [from 0.83 (SD 0.19) to 1.09 (SD 0.36)] and acute increases in afterload [to 1.23 (SD 0.17)]. All the above increases and decreases and r values were significant (P < 0.05 vs. baseline). In conclusion, TD MPI can rapidly quantify alterations in LV contractile state but is affected by acute alterations in preload and afterload.