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

Echocardiographic Assessment of Right Ventricular Function in Paediatric Heart Disease: A Practical Clinical Approach

As the right ventricle (RV) plays an integral role in different paediatric heart diseases, the accurate assessment of RV size and function is essential in the diagnosis, management, and prognostication of congenital and acquired cardiac lesions. Yet, echocardiographic evaluation of the RV is challenging because of its complex and variable morphology, its different physiology compared with the left ventricle, and its capability to adapt to different loading conditions associated with congenital and acquired heart diseases within certain ranges. Reliable echocardiographic detection of RV systolic and diastolic dysfunction remains challenging while important for patient management. This review provides an updated, practical approach to assessing RV function in structurally normal hearts and in children with common congenital heart defects and in those with pulmonary hypertension. We also review the impact of tricuspid valve function on RV functional parameters. There is no single functional RV parameter that uniquely describes RV function; instead a combination of different parameters is recommended in clinical practice. Qualitative and quantitative analysis of RV function will be reviewed including more recent techniques such as speckle tracking and 3D echocardiography.

Prenatally diagnosed case of tricuspid valve dysplasia: A case report with review of the literature

We present a case of fetal tricuspid valve dysplasia (TVD) and pulmonary atresia, diagnosed during a routine obstetric ultrasound scan. Serial fetal echocardiographic evaluations revealed progressively augmented prodigious thickening of the tricuspid valvular and subvalvular structures, which eventually extensively obliterated the right ventricle cavity. Thickened dysplastic valve displayed a "cotton-wool" appearance. Unusual configurations of three vessels in the three-vessel view were also observed on a consecutive gray scale and color Doppler scans. During pregnancy, the fetus exhibited satisfactory growth parameters, and complications of progressive hemodynamic compromise associated with TVD and pulmonary atresia such as grievous hydrops or arrhythmia did not develop till 39 weeks of gravidity.

Influence of Cardiac Function and Loading Conditions on the Myocardial Performance Index - Theoretical Analysis Based on a Mathematical Model

BACKGROUND

The myocardial performance index (MPI) has emerged as a Doppler-derived index for global ventricular function capable of estimating combined systolic and diastolic performance. While several studies have reported its load-dependency, responses of the MPI to various hemodynamic changes have not been fully characterized.

METHODS AND RESULTS

The response characteristics of the MPI were examined and compared with ejection fractions (EF) by changing hemodynamic parameters within the physiological range in a lumped parameter model of the cardiovascular system. At baseline, the MPI was 0.42 and the EF was 0.68. Heart rate increase resulted in a decrease in EF and an increase in the MPI. Reduction in end-systolic elastance decreased EF and increased the MPI. Volume overload and ventricular stiffening did not affect EF but paradoxically reduced the MPI. Increased afterload due to higher systemic resistance resulted in a decrease in EF and increase in the MPI, but afterload increase caused by reduced arterial compliance led to a decrease in both EF and MPI. These MPI characteristics caused paradoxical improvement of the MPI during disease progression of chronic heart failure in a simulation of mitral regurgitation.

CONCLUSIONS

The MPI is affected by a wider variety of hemodynamic parameters than EF. In addition, it is predicted to decrease paradoxically with volume overload, reduction in arterial compliance, or ventricular diastolic stiffening. These MPI characteristics should be considered when assessing cardiovascular dynamics using this index.

Evaluation of right ventricular function in patients with tetralogy of Fallot using the myocardial performance index and isovolumic acceleration: a comparison with cardiac magnetic resonance imaging

BACKGROUND

Assessment of right ventricular function is a key point in the follow-up of operated patients with tetralogy of Fallot. Cardiac magnetic resonance assessment of right ventricular function is considered the gold standard. However, this technique is expensive, has limited availability, and requires significant expertise to acquire and interpret the images. Myocardial performance index and isovolumic acceleration have recently been studied for the assessment of right ventricular function and are shown to be simple yet powerful tools for assessing patients with right ventricular dysfunction of various origins.

METHODS

In this study, the integrity of myocardial performance index and isovolumic acceleration obtained by tissue Doppler imaging echocardiography to quantify right ventricular function was assessed in 31 patients operated for tetralogy of Fallot. Myocardial performance index and isovolumic acceleration measurements were compared with the parameters derived by cardiac magnetic resonance imaging.

RESULTS

In this study, a significant correlation has not been detected between cardiac magnetic resonance-originated right ventricular ejection fraction, pulmonary regurgitation fraction and myocardial performance index, isovolumic acceleration obtained by tissue Doppler imaging echocardiography from the lateral tricuspid annulus of the right ventricle.

CONCLUSION

We have concluded that when evaluated separately, myocardial performance index and isovolumic acceleration obtained from tissue Doppler imaging echocardiography can be used in the long-term follow-up of patients who have been operated for tetralogy of Fallot, but that they do not show correlation with cardiac magnetic resonance-originated right ventricle ejection fraction and pulmonary regurgitation fraction.

The Assessment and Potential Implications of the Myocardial Performance Index Post Exercise in an at Risk Population

BACKGROUND

The myocardial performance index (MPI) first described by Chuwa Tei in 1995 is a relatively new echocardiographic variable used for assessment of overall cardiac function. Previous studies have demonstrated the MPI to be a sum representation of both left ventricular systolic and diastolic function with prognostic value in patients with coronary artery disease as well as symptomatic heart failure.

METHODS

Ninety patients with either established coronary artery disease (CAD) or CAD risk factors underwent routine treadmill exercise stress testing with two-dimensional Doppler echocardiography using the standard Bruce protocol. Both resting and stress MPI values were measured for all 90 of the patients.

RESULTS

Using a normal MPI cut off of ≤ 0.47, the prevalence of an abnormal resting MPI in our 90 subjects was 72/90 or 80% and the prevalence of an abnormal stress MPI in our 90 subjects was 48/90 or 53.33%. The average MPI observed in the resting portion of the stress test for the cohort was: 0.636 with a standard deviation of 0.182. The average MPI in the stress portion of the stress test for the cohort was 0.530 with a standard deviation of 0.250. The P value with the use of a one-tailed dependent T test was calculated to be < 0.05.

CONCLUSION

We postulate that these findings reflect that the MPI (Tei) index assessed during exercise may be a sensitive indicator of occult coronary disease in an at risk group independent of wall motion assessment.

Impact of acute changes of left ventricular contractility on the transvalvular impedance: validation study by pressure-volume loop analysis in healthy pigs

BACKGROUND

The real-time and continuous assessment of left ventricular (LV) myocardial contractility through an implanted device is a clinically relevant goal. Transvalvular impedance (TVI) is an impedentiometric signal detected in the right cardiac chambers that changes during stroke volume fluctuations in patients. However, the relationship between TVI signals and LV contractility has not been proven. We investigated whether TVI signals predict changes of LV inotropic state during clinically relevant loading and inotropic conditions in swine normal heart.

METHODS

The assessment of RVTVI signals was performed in anesthetized adult healthy anesthetized pigs (n = 6) instrumented for measurement of aortic and LV pressure, dP/dtmax and LV volumes. Myocardial contractility was assessed with the slope (Ees) of the LV end systolic pressure-volume relationship. Effective arterial elastance (Ea) and stroke work (SW) were determined from the LV pressure-volume loops. Pigs were studied at rest (baseline), after transient mechanical preload reduction and afterload increase, after 10-min of low dose dobutamine infusion (LDDS, 10 ug/kg/min, i.v), and esmolol administration (ESMO, bolus of 500 µg and continuous infusion of 100 µg·kg-1·min-1).

RESULTS

We detected a significant relationship between ESTVI and dP/dtmax during LDDS and ESMO administration. In addition, the fluctuations of ESTVI were significantly related to changes of the Ees during afterload increase, LDDS and ESMO infusion.

CONCLUSIONS

ESTVI signal detected in right cardiac chamber is significantly affected by acute changes in cardiac mechanical activity and is able to predict acute changes of LV inotropic state in normal heart.

Extent of load-independence of pressure-normalized stress in swine

A load-independent index of myocardial contractility provides a measure of cardiac function. Previous contractility indices have been shown to be either load-dependent or invasive. We sought to determine the extent of load (preload and afterload)-independence of dσ*/dtmax (σ* is pressure-normalized stress) in comparison with other well-established indices. Six anaesthetized pigs underwent left ventricular pressure-volume measurements under various load conditions. The average preload was decreased by 70.0 ± 15.0% (from 39.2 ± 6.4 mL to 11.7 ± 7.7 mL) and increased by 49.3 ± 5.9% (from 35.1 ± 7.4 mL to 51.7 ± 8.9 mL). The average afterload was increased by 74.3 ± 43.5% (from 3.3 ± 0.6 mmHg/mL to 5.7 ± 1.7 mmHg/mL). When preload was reduced within an average of 21.7% (39.2 ± 6.4 mL to 30.7 ± 6.2 mL) using occlusion of the inferior vena cava, dσ*/dt max did not change significantly (6.50 ± 1.10 s⁻¹ vs 6.60 ± 0.90 s⁻¹, P = non-significant [NS]). When preload was increased within an average of 29.3% (35.1 ± 7.4 mL to 45.4 ± 7.3 mL) from infusion of normal saline, dσ*/dt max did not change significantly (7.04 ± 1.00 s⁻¹ vs 7.29 ± 1.10 s⁻¹, P = NS). When afterload was increased within an average of 42.4% (3.3 ± 0.6 mmHg/mL to 4.7 ± 1.0 mmHg/mL) using intra-aortic balloon occlusion, dσ*/dtmax did not change significantly (6.72 ± 1.18 s⁻¹ vs 6.89 ± 1.28 s⁻¹, P = NS). As expected, dσ*/dtmax was significantly increased with dobutamine. A linear regression showed no correlation between dσ*/dtmax and preload (r² = 0.02, P = 0.17) within a maximum range of -30% to +50% of preload change, or between dσ*/dtmax and afterload (r² = 0.03, P = 0.36) within maximum range of 0-100% of afterload increase, respectively. In conclusion, dσ*/dtmax is independent of loading conditions within an average of 21.7% of preload decrease, 29.3% of preload increase, 42.4% of afterload increase, and sensitive to dobutamine infusion.

Pulsed tissue Doppler imaging of the left ventricular septal mitral annulus in healthy dogs

This study evaluated pulsed TDI variables including the isovolumic time interval and duration of the major wave in a population of large healthy dogs. Longitudinal myocardial motion at the septal mitral annulus was evaluated with pulsed TDI in 45 healthy adult dogs. Maximal myocardial velocities, isovolumic time intervals, and duration of the myocardial waves were measured. The correlation between time intervals and velocity variables was also investigated. The mean maximal systolic velocity was 6.92 ± 1.78 cm/sec, the mean early diastolic velocity (Em) was 6.58 ± 1.81 cm/sec, the mean late diastolic velocity (Am) was 5.10 ± 2.00 cm/sec, the mean isovolumic contraction time (IVCT) was 53.61 ± 95.13 msec, and the mean isovolumic relaxation time (IVRT) was 26.74 ± 57.24 msec. The early diastolic mitral inflow velocity (E)/Em ratio was 10.94 ± 3.27 while the Em/Am ratio was 1.40 ± 0.40. There was a negative correlation between Am duration and Am amplitude, and a positive correlation between the IVRT and Em/Am ratio (p < 0.05). The normal LV parameter using pulsed TDI method could be used as the reference range for identifying myocardial dysfunction in dogs.

Myocardial performance index is sensitive to changes in cardiac contractility, but is also affected by vascular load condition

Myocardial performance index (MPI), or Tei index, is measured by Doppler echocardiography in clinical practice. MPI has been shown to be useful in evaluating left ventricular (LV) performance and predicting prognosis in cardiac patients. However, the effects of LV load and contractile states on MPI remain to be thoroughly investigated. In 14 anesthetized dogs, we obtained LV pressure-volume relationship with use of sonomicrometry and catheter-tip manometry. MPI was determined from the time derivative of LV volume and pressure. LV end-systolic pressure-volume ratio (Ees'), effective arterial elastance (Ea) and LV end-diastolic volume (Ved) were used as indices of LV contractility, afterload and preload, respectively. Hemodynamic conditions were varied over wide ranges [heart rate (HR), 66-192 bpm; mean arterial pressure, 71-177 mmHg] by infusing cardiovascular agents, by inducing ischemic heart failure and by electrical atrial pacing. Multiple linear regression analysis of pooled data (66 data sets) indicated that MPI (0.6-1.8) significantly correlated with Ees' [1.5-17.5 mmHg · ml(-1), p<0.0001, standard partial regression coefficient (β) =-0.66], Ea (3.6-21.9 mmHg · ml(-1), p<0.001, β = 0.4) and Ved (11-100 ml, p<0.0001, β = -0.69). MPI directly correlated with the time constant of isovolumic relaxation (19-66 ms, p<0.05), but not with HR or LV diastolic-stiffness (all p>0.1). Theoretical analysis also indicated that MPI decreases following the increases in LV contractility and in preload, while it increases in response to an increase in LV afterload. We conclude that MPI sensitively detects changes in LV contractility. However, MPI is also affected by changes in LV afterload and preload.

Improvement of myocardial performance (Tei) index closely reflects intrinsic improvement of cardiac function: assessment in revascularized hibernating myocardium

BACKGROUND

Myocardial performance index (MPI), or Tei index, is an indicator of systolic and diastolic myocardial function. MPI increases in case of cardiac dysfunction; however, whether reversal of left ventricular dysfunction is also reflected by concomitant improvement (i.e., decrease) of MPI is unknown.

METHODS

Fifty-two patients with chronic ischemic cardiomyopathy and viable myocardium by dobutamine stress echocardiography were studied by echocardiography before and more than 4 months after cardiac revascularization. Patients were in optimal medical therapy, which remained unchanged following revascularization.

RESULTS

At baseline, ejection fraction (EF: 32 ± 6%) and wall motion score index (WMSI: 2.37 ± 0.32) were impaired, and MPI averaged 0.71 ± 0.19. Revascularization markedly improved EF (44 ± 10%, P < 0.0001) and WMSI (1.77 ± 0.44, P < 0.0001). MPI also improved (0.59 ± 0.26, P < 0.0001), and its decrease was significantly correlated with the improvement in EF (r =-0.68, P < 0.0001) and to the extent of viable myocardium (r =-0.45, P = 0.0007). Responders to revascularization (≥5% increase in EF at follow-up, n = 40% and 77%) achieved a significant improvement in MPI at follow-up in contrast with nonresponders (-23 ± 25% vs. 0.02 ± 0.18%, P = 0.001). Improvement in MPI was largely driven by a significant reduction in isovolumic contraction time (P < 0.001) with consequent prolongation of the ejection phase.

CONCLUSION

In patients with chronic ischemic cardiomyopathy, MPI improves along with recovery of function, reflecting the intrinsic improvement of viable segments induced by revascularization.

Usefulness of Tei index in patients with rheumatic mitral regurgitation and apparently normal left ventricular ejection fraction

BACKGROUND AND AIM

Rheumatic mitral regurgitation is rather common in developing countries. It usually progresses insidiously, because the heart compensates for increasing regurgitant volume by left-atrial enlargement, causes left-ventricular overload and dysfunction, and yields poor outcome when it becomes severe. Doppler-echocardiographic methods can be used to quantify the severity of mitral regurgitation. It is known that ejection fraction underestimates the presence of left ventricular dysfunction in these patients. This study aimed to study global cardiac function of these patients by using LV Tei index.

METHODS

One hundred patients with rheumatic mitral regurge predominantly were included (40 males and 60 females; aged 10-24 years, median 20.6 years). All participants were subjected to full echocardiographic study including total isovolumic index (Tei index = isovolumic relaxation time IRT + isovolumic contraction time ICT/ejection time ET) for the left ventricle. Special attention was paid to grading of severity of the mitral regurgitation.

RESULTS

LV ejection fraction was preserved in all cases but, however, the total left isovolumic index was prolonged 0.56 ± 3 in 64 of them (34 females and 30 males) denoting masked LV dysfunction P < .00001. There was a correlation of increasing severity of dysfunction with the degree of mitral regurgitation.

CONCLUSION

Ejection fraction underestimates the presence of left ventricular dysfunction in these patients. However, this was unmasked by the Tei index which could be an additive data for detecting early left ventricular dysfunction.

Improvement in Left Ventricular Systolic and Diastolic Performance During Ranolazine Treatment in Patients With Stable Angina

Purpose: Ranolazine is a novel antianginal medication that acts by ameliorating disturbed sodium and calcium homeostasis. By preventing myocyte sodium and calcium overload, ranolazine also have potential beneficial effects on myocardial function. Experimental models support this concept, as do 2 small studies in human participants receiving ranolazine intravenously. We evaluated changes in parameters of left ventricular function in stable angina patients treated with oral ranolazine. Methods: Twenty-two participants were enrolled with Doppler echocardiography performed at baseline and a mean of 2 months after initiation of treatment. Results: Global left ventricular function, as assessed by the myocardial performance index, was significantly improved on drug therapy (P < .0001). This was due to improvement in both diastolic and systolic parameters. Of 21 patients, 17 reported less angina and 8 patients reported an increase in activity level. Conclusions: We report improved parameters of left ventricular function in response to ranolazine as used in the clinical setting.

The impact of metabolic syndrome on left ventricular myocardial performance

BACKGROUND

Metabolic syndrome (MetS) is common and is associated with increased cardiovascular morbidity and mortality. Recent prospective studies suggested that MetS is associated with increased risk of heart failure. In the present cross-sectional study, we examined the association between left ventricular myocardial performance with MetS.

MATERIALS AND METHODS

A total of 550 non-diabetic subjects, 275 without MetS and 275 with MetS, matched for gender, age and body mass index and free of clinically apparent macrovascular disease were studied. MetS was diagnosed using the NCEP-ATP III criteria. Left ventricular myocardial performance was assessed using the Tei index.

RESULTS

Both men and women with MetS had higher values of the Tei index, indicating worse myocardial performance, in comparison with those without MetS (p < 0.001). Participants with a cluster of more components of the MetS had higher Tei index values than those with fewer components of the MetS. In addition, among normotensive subjects, those with MetS had significantly higher Tei index values than subjects without MetS. Multivariate linear regression analysis, after adjustment for age and body mass index, demonstrated that MetS status and from the individual components of the MetS, high fasting blood glucose levels, higher blood pressure, low high density lipoprotein levels and high waist circumference were associated with worse myocardial performance.

CONCLUSION

MetS is associated with subclinical myocardial dysfunction in both men and women. Strategies to reduce the cardiovascular burden and the risk of heart failure associated with MetS should aim at prevention of the MetS and its related conditions.

The relationship between invasive hemodynamic measurements and tissue Doppler-derived myocardial velocity and acceleration during isovolumic relaxation in healthy dogs

This study investigated the feasibility of using the values of tissue Doppler imaging (TDI)-derived myocardial velocity during isovolumic relaxation (V(IR)) and myocardial acceleration during isovolumic relaxation (ACC) obtained from the left ventricular (LV) free wall to evaluate LV relaxation in normal dogs. Seven dogs were anesthetized, and dobutamine or esmolol was infused at a rate of 5.0 and 10.0 mug/kg/min or 100 and 500 mug/kg/min, respectively, via a cephalic vein. The order of drug administration (dobutamine or esmolol) was assigned to each dog. Simultaneous pulsed-Doppler (PD) echocardiography, TDI and hemodynamic measurements were performed. Compared with the baseline values, dobutamine significantly increased dP/dt min, but significantly shortened tau (tau). Similarly, esmolol significantly decreased dP/dt min, but significantly prolonged tau. Compared with the baseline values, dobutamine significantly increased V(IR) and ACC, and esmolol significantly decreased V(IR) and ACC. Both dP/dt min and tau were significantly correlated with TDI-derived IVRT (r=-0.43 and 0.74), V(IR) (r=0.85 and -0.49) and ACC (r=0.84 and -0.52). These results indicate that the TDI-derived V(IR) and ACC values obtained from the LV free wall can potentially be used to assess LV relaxation in dogs.

Usefulness of early diastolic mitral annular velocity to predict plasma levels of brain natriuretic peptide and transient heart failure development after device closure of atrial septal defect

Device closure of atrial septal defect (ASD) is sometimes followed by elevation of plasma brain natriuretic peptide (BNP), a marker of heart failure, and progression to heart failure. This study tested the hypothesis that the underlying diastolic dysfunction, assessed on tissue Doppler images (TDI) before device closure, can predict BNP level after ASD closure. The study subjects were 39 consecutive patients (age 27.5 +/- 16.3 years, range 5 to 63) who underwent device closure for ASD. Echocardiographic evaluation using TDI and 2-dimensional and pulse wave Doppler were performed, together with plasma BNP measurement 1 day before and 2 days after ASD closure. Before ASD closure, an age-dependent decrease was noted in left ventricular relaxation, assessed by early diastolic mitral annular velocity. ASD closure resulted in a decrease in early diastolic mitral annular velocity (from 14.7 to 12.3 cm/s, p <0.05) despite an increase in the left ventricular dimension (84% to 92% vs normal, p <0.05). These changes were associated with a parallel increase in BNP (17.9 to 48.4 pg/ml, p <0.05). Stepwise multivariate linear regression identified early diastolic mitral annular velocity before ASD closure and age as independent predictors of BNP levels after ASD closure (p <0.05). Consistent with this result, 2 patients with the lowest early diastolic mitral annular velocity developed exertional dyspnea after the procedure. In conclusion, our results indicate that TDI measurements could be useful to detect underlying diastolic dysfunction that can potentially cause heart failure after ASD closure and emphasize the importance of ASD closure at a young age before impairment of left ventricular relaxation.

Methods and reliability of tissue Doppler imaging for assessment of left ventricular radial wall motion in horses

BACKGROUND

Noninvasive assessment of left ventricular (LV) function is incompletely studied in horses.

OBJECTIVES

The goals of this study were to investigate the feasibility, techniques, and reliability of tissue Doppler imaging (TDI) for characterization of LV radial wall motion in healthy horses.

ANIMALS

Three Standardbreds, 3 Thoroughbreds; age 8-14 years; body weight 517-606 kg.

METHODS

Repeated echocardiographic examinations were performed by 2 observers in unsedated horses using TDI. Test reliability was determined by estimating measurement variability, within-day interobserver variability, and between-day interobserver and intraobserver variability of all echocardiographic variables. Variability was expressed as coefficient of variation (CV) and the absolute value below which the difference between 2 measurements will lie with 95% probability.

RESULTS

Assessment of LV radial wall motion by TDI was feasible in all horses. Measurement variabilities were very low (CV < 5%) to low (CV 5-15%) for most variables. Within-day interobserver variability as well as between-day interobserver and intraobserver variabilities were low to moderate (CV 16-25%) for most variables. All pulsed-wave TDI variables of systolic LV function showed very low to low variability, whereas some of the variables of LV diastolic and LA function showed moderate to high (CV > 25%) variability. Pulsed-wave TDI variables appeared more reliable than color TDI variables.

CONCLUSIONS AND CLINICAL IMPORTANCE

Measurement of TDI indices of LV function is feasible and reliable in adult Standardbred and Thoroughbred horses. The clinical relevance of LV function assessment by TDI remains to be determined.

Differential strain and velocity generation along the right ventricular free wall in pulmonary hypertension

BACKGROUND

In contrast to the homogeneously distributed deformation properties within the left ventricle, the right ventricular (RV) free wall (RVFW) shows a more inhomogeneous distribution. It has been demonstrated that pulmonary hypertension (PH) results in significant RVFW mechanical delay.

OBJECTIVE

To assess the effect of the degree of pulmonary arterial systolic pressure on the RVFW strain gradient and on myocardial velocity generation.

METHODS

Peak longitudinal strain and velocity data were collected from three different segments (basal, mid- and apical) of the RVFW in 17 normal individuals and 31 PH patients.

RESULTS

A total of 144 RV wall segments were analyzed. RVFW strain values in individuals without PH were higher in the mid and apical segments than in the basal segment. In contrast, RVFW strain in PH patients was higher in basal segments and diminished toward the apex. In terms of RVFW velocities, both groups showed decremental values from basal to apical segments. Basal and mid-RVFW velocities were significantly lower in PH patients than in individuals without PH.

CONCLUSIONS

PH results in significant alterations of strain and velocity generation that occurs along the RVFW. Of these abnormalities, the reduction in strain from the mid and apical RVFW segments was most predictive of PH. It is important to be aware of these differences in strain generation when studying the effect of PH on the right ventricle. Additional studies are required to determine whether these differences are due to RV remodelling.

Relationship of magnetic resonance imaging estimation of myocardial iron to left ventricular systolic and diastolic function in thalassemia

OBJECTIVES

We sought to evaluate whether echocardiographic diastolic function indices correlate with myocardial iron and systolic function in patients with transfusion-dependent thalassemia (TDT) who are at risk for cardiomyopathy.

BACKGROUND

In thalassemia syndromes, there is an important clinical need to risk stratify patients for the development of iron-overload cardiomyopathy so that chelation therapy can be adjusted and cardiac morbidity averted. This purpose may be served by measuring the magnetic resonance imaging (MRI)-derived parameter T2*, which varies inversely with tissue iron concentration but has limited availability. As diastolic dysfunction may precede systolic dysfunction, we sought to directly compare more readily available echocardiographic indices of diastolic function to myocardial T2* and ejection fraction (EF).

METHODS

We identified 47 paired echocardiography and MRI examinations in 24 patients with TDT. Echocardiographic measurements of transmitral flow velocities (E, A), tissue Doppler velocities (E'), and left ventricular volume and EF were compared with MRI measurements of myocardial T2*, ventricular volume, and EF.

RESULTS

All patients had a restrictive filling pattern (E/A >or=1.5 and deceleration time <140 ms) and normal relaxation. There was no significant correlation between E/E' or the Tei index versus EF. Although E/A and E' had statistically significant correlations with EF, the relationships were weak with all correlation coefficients <0.52. The parameters E/A, E', E/E', and the Tei index did not significantly correlate with myocardial iron concentration as assessed by MRI T2*. Increased myocardial iron as measured by T2* was strongly associated with lower left ventricular EF, with a T2* <9 ms having a sensitivity of 100% and specificity of 89% for MRI EF <50%.

CONCLUSIONS

In patients with TDT, echocardiographic diastolic function parameters correlated poorly with EF and myocardial T2* and were thus not well-suited for risk stratification. Myocardial T2* had a strong relationship with EF and appears to be a promising approach for predicting the development of heart failure and for iron chelator dose adjustment.

Tei index to assess perioperative left ventricular systolic function in patients undergoing mitral valve repair

BACKGROUND

Using echocardiography, perioperative assessment of systolic function by fractional area change (FAC) is questionable in patients suffering from mitral regurgitation (MR). Tei index, an index expressing global cardiac function, has been reported to be unchanged after mitral valve surgery. We tested the hypothesis where the Tei index could be useful in assessing the perioperative cardiac function in patients undergoing mitral valve repair (MVR).

METHODS

Twenty-five patients were enrolled. Transoesophageal echocardiography was performed perioperatively before and after the correction of MR. We compared the impact of the MVR on the left ventricular FAC and the Tei index. FAC was calculated from the transgastric short-axis view and Tei index was determined from the four chambers and deep transgastric views.

RESULTS

Two patients were excluded because of poor acoustic windows. FAC significantly decreased after MVR from 53 (9)% to 42 (10)% (P<0.001), while Tei index was unaffected [0.46 (0.16) vs 0.47 (0.17), NS]. A significant relationship was found between the preoperative Tei index and the postoperative FAC (R=-0.64, P<0.001). Moreover, a significant and clinically relevant relationship was determined between the predicted (using preoperative Tei index) and the measured postoperative FAC (R=0.64, P<0.001).

CONCLUSIONS

FAC but not the Tei index is influenced by MVR. The preoperative determination of the Tei index allows predicting postoperative FAC and offers the opportunity to identify patients in whom a severe unsuspected systolic dysfunction could render difficult the weaning from cardiopulmonary bypass.

Assessing diastolic function with Doppler echocardiography using a novel index: ratio of the transmitral early diastolic velocity to pulmonary diastolic velocity

We developed a novel index to assess left ventricular (LV) relaxation as the ratio of transmitral early diastolic velocity to pulmonary diastolic velocity (E/D ratio). Mixed breed dogs (n=7) were anesthetized and their respiration was controlled. A 3.5-Fr micromanometer-tipped catheter was placed into the left ventricle. Dobutamine (5.0 or 10 microg/kg/min) or esmolol (100 or 500 microg/kg/min) was administered via the cephalic vein. The transmitral flow (TMF) and pulmonary venous flow (PVF) were recorded using transthoracic echocardiography from the apical long-axis view. The heart rate, systolic LV pressure, +dP/dt, and -dP/dt were significantly elevated by dobutamine, but significantly reduced by esmolol. Dobutamine significantly decreased tau, whereas esmolol significantly increased tau. The TMF-derived E and PVF-derived D wave velocities increased significantly with dobutamine, but decreased significantly with esmolol. A significant correlation was detected between the E and D wave velocities (r=0.92). Consequently, the E/D ratio was decreased significantly with dobutamine, and increased significantly with esmolol. Furthermore, the E/D ratio was significantly correlated with -dP/dt (r= -0.64) and tau (r=0.84). Our results suggest that the E/D ratio reflects LV relaxation, and may potentially provide further information on LV relaxation.

Comparison between pulsed-wave Doppler- and tissue Doppler-derived Tei indices in fetuses with and without congenital heart disease

OBJECTIVES

The aim of this study was to compare the right (RV) and left (LV) ventricular Tei indices obtained by pulsed-wave Doppler (PD) and tissue Doppler (TD) methods in fetuses with structurally normal and abnormal hearts.

METHODS

This was a retrospective cross-sectional study of 147 fetuses that had a fetal echocardiogram and Tei index measured during a 2-year period. The RV and LV Tei indices were measured using both PD and TD methods. The difference between the two methods of Tei index measurement was tested using paired sample t-test, Pearson correlation coefficient was used to examine their relationship, and the agreement between the methods was tested using Bland-Altman analysis.

RESULTS

A total of 87 fetuses had normal hearts and 60 had a congenital heart defect. Both PD and TD Tei indices were measured successfully from at least one ventricle in 123 cases and from both ventricles in 110 cases. The mean TD Tei index was significantly higher than the mean PD Tei index for both ventricles (P < 0.0001). There was a weak but statistically significant correlation between the PD and TD Tei indices of the right ventricle (r = 0.20, P = 0.029), whereas the PD and TD Tei indices of the left ventricle did not correlate significantly (r = 0.04, P = 0.684). When pairs of Tei indices measured by two different methods (123 pairs for the right ventricle and 111 for the left ventricle) were tested with Bland-Altman analysis, the bias and precision were 0.147 and 0.254, respectively, for the right ventricle, and 0.299 and 0.276, respectively, for the left ventricle.

CONCLUSIONS

Correlation between Tei indices measured by PD and TD methods is weak and the agreement between individual measurements is poor. Therefore, they should not be used interchangeably in the assessment of fetal cardiac function.

Early impairment of left ventricular function in hypercholesterolemia and its reversibility after short term treatment with rosuvastatin

BACKGROUND

Hypercholesterolemia contributes to coronary heart disease but little is known about its direct effect on myocardial function. We evaluated left ventricular function using echocardiography and the effect of treatment with rosuvastatin in a group of patients with primary hypercholesterolemia.

METHODS AND RESULTS

Thirty-three patients with primary hypercholesterolemia (HC) and without evidence of coronary heart disease and 25 aged matched healthy volunteers (C) were submitted to conventional echocardiography, pulsed wave tissue Doppler imaging (PWTDI), color Doppler myocardial imaging (CDMI) and integrated backscatter (IBS). Echocardiographic evaluation was repeated after 6 months of treatment with rosuvastatin (10mg/day) in 17 patients. Compared with C, patients with HC showed lower E/A ratio (p<0.0001) and higher Tei index mit (p<0.0001), as well as lower PW TDI E/A both at septum (p<0.0001) and at lateral level (p<0.0001) and higher modified Tei index both at septal annulus (p<0.0001) and lateral annulus (p<0.0001). Integrated backscatter parameters were significantly reduced in patients with HC (CVIsept p<0.0001 and CVI post wall p<0.05). CDMI derived indices in the two groups were not different. After 6 months of Rosuvastatin treatment a significant reduction of LDL cholesterol levels (51%, p<0.0001) was registered in HC patients together with a significant improvement of longitudinal global systolic and diastolic function (Tei index) and myocardial intrinsic contractility (CVI).

CONCLUSIONS

These data suggest that in patients with hypercholesterolemia exists an early cardiomyopathy characterized by systolic and diastolic dysfunction. That could produce a substratum for an "impaired preconditioning". Rosuvastatin seems able to revert systolic abnormalities.

Volume loading-related changes in tissue Doppler images derived from the tricuspid valve annulus in dogs

OBJECTIVE

To investigate the relationship between preload and tricuspid valve annulus-derived tissue Doppler imaging (TDI) as an index of right ventricular (RV) filling in dogs.

ANIMALS

7 Beagles.

PROCEDURES

Peak systolic RV pressure and RV end-diastolic pressure (RVEDP) were measured in anesthetized dogs. Pulsed Doppler was used to measure tricuspid valve inflow and pulmonary valve outflow velocities. The TDI velocities were measured at the lateral corner of the tricuspid valve annulus. Lactated Ringer's solution was infused at 200 mL/kg/h for 60 minutes via the cephalic vein.

RESULTS

IV infusion significantly increased heart rate, RV pressure, and RVEDP. Early diastolic flow (E-wave) and ejection time significantly increased. The myocardial performance index (MPI) significantly decreased. Intravenous infusion significantly increased the ratio of the E'-wave (peak myocardial velocity during early diastole) to the A'-wave (peak myocardial velocity during late diastole; E':A' ratio) and myocardial velocity during systole (S'), early diastole (E'), and late diastole (A'). The TDI-isovolumic relaxation time and TDI-MPI decreased significantly. The RVEDP was correlated with late diastolic flow (A-wave), ratio of the E-wave to the A-wave (E:A ratio), E'-wave, A'-wave, S'-wave (peak myocardial velocity during systole), TDI-isovolumic relaxation time, TDI-MPI, and ratio of the E-wave to the E'-wave (E: E' ratio). The A-wave and E:A ratio and TDI-derived isovolumic relaxation time, S' duration, and E'-wave could predict the RVEDP.

CONCLUSIONS AND CLINICAL RELEVANCE

The TDI velocities were affected by RV filling pressure in healthy dogs, whereas other TDI profiles, such as MPI and E':A' ratio, were independent of acute filling abnormalities.

The impact of metabolic syndrome on left ventricular function: evaluated by using the index of myocardial performance

AIM

To evaluate the impact of metabolic syndrome on global left ventricular function by using the index of myocardial performance.

METHODS

The study population included 106 patients with metabolic syndrome (66 male, 40 female, mean age =54+/-11 years) and 106 control subjects without metabolic syndrome (71 male, 35 female, mean age=53+/-10). The diagnosis of metabolic syndrome was based on The National Cholesterol Education Program Adult Treatment Panel III criteria. All patients underwent two-dimensional and Doppler echocardiographic examination. The index of myocardial performance was determined as the sum of isovolumic relaxation time and isovolumic contraction time divided by left ventricular ejection time.

RESULTS

The index of myocardial performance was found to be significantly higher in patients with metabolic syndrome compared with control subjects without metabolic syndrome (0.55+/-0.06 vs 0.38+/-0.04 respectively, p<0.001).

CONCLUSION

In the present study, we have shown the presence of impaired global left ventricular function in patients with metabolic syndrome compared with control subjects without metabolic syndrome. This finding emphasizes the importance of early diagnosis and management of metabolic syndrome to prevent the progression of ventricular dysfunction to overt structural and symptomatic cardiac disease.

Comparison of the myocardial performance index derived by use of pulsed Doppler echocardiography and tissue Doppler imaging in dogs with volume overload

OBJECTIVE

To investigate the relationship between the myocardial performance index (MPI) determined by use of pulsed Doppler (PD) echocardiography and tissue Doppler imaging (TDI) in the response to volume overload-related changes in left ventricle (LV) performance.

ANIMALS

7 male Beagles.

PROCEDURES

Dogs were anesthetized and intubated. A 6-F fluid-filled catheter was placed in the LV to measure LV peak systolic (LVPs) and LV end-diastolic (LVED) pressures. Preload was increased by IV infusion of lactated Ringer's solution (rate of 200 mL/kg/h for 60 minutes) into a cephalic vein. Transmitral flow velocities and aortic outflow were measured, and TDI velocities were obtained from the 4-chamber view.

RESULTS

Acute volume overload induced a significant increase in heart rate, LVPs pressure, and LVED pressure, compared with baseline values. A significant decrease in the PD-MPI and TDI-MPI values and a significant correlation (r = 0.70) between PD-MPI and TDI-MPI were detected. The PD-derived A-wave velocity, ejection time, and isovolumic relaxation time (IRT) and the TDI-derived IRT, MPI, and ratio of the velocity of the E wave to the velocity of the ventricular portion of the E wave during early diastole had equal ability to predict LVED pressure (r(2) = 0.63).

CONCLUSIONS AND CLINICAL RELEVANCE

The TDI-MPI was closely correlated with LV filling pressure and may be helpful in evaluating global cardiac function in dogs.

Metabolic acidosis decreases fetal myocardial isovolumic velocities in a chronic sheep model of increased placental vascular resistance

We hypothesized that acute fetal metabolic acidosis decreases fetal myocardial motion in a chronic sheep model of increased placental vascular resistance ( Rua). Eleven ewes and fetuses were instrumented at 118–122 days of gestation. After 5 days of recovery and 24 h of placental embolization to increase Rua, longitudinal myocardial velocities of the right and left ventricles and interventricular septum (IVS) were assessed at the level of the atrioventricular valve annuli via tissue Doppler imaging (TDI). Ventricular inflow (E and A waves) and outflow velocities were obtained, and cardiac outputs were calculated. All measurements were performed at baseline and during fetal acidosis caused by epidural anesthesia-induced maternal hypotension, which decreased uterine artery volume blood flow, fetal oxygenation, arterial pH, and base excess and increased lactate. Compared with baseline, the peak isovolumic myocardial contraction and relaxation velocities of the ventricles and IVS, early relaxation velocity (E′) of the ventricles, and systolic velocity of the IVS decreased during metabolic acidosis. The proportion of isovolumic contraction time of the cardiac cycle increased but the isovolumic relaxation and ejection time proportions and the TDI Tei index did not change. The E-to-E′ ratio for both ventricles was higher during metabolic acidosis than at baseline. During metabolic acidosis, right and left ventricular cardiac outputs remained unchanged compared with baseline. In sheep fetuses with increased Rua and acute metabolic acidosis, global cardiac function was preserved. However, acute metabolic acidosis impaired myocardial contractility during the isovolumic phase and relaxation during the isovolumic and early filling phases of the cardiac cycle.

Alternate Site Atrial Pacing in the Young: Conventional Echocardiography and Tissue Doppler Analysis of the Effects on Atrial Function and Ventricular Filling

BACKGROUND

Although the right atrial appendage (RAA) is typically used for atrial pacing lead implant, recent studies have shown benefits of alternate site atrial pacing (ASAP) in the elderly. However, comparable studies in the young are lacking.

METHODS

To investigate effects of ASAP on cardiac function and atrioventricular mechanical interactions in the young, 26 subjects (ages 10 to 23 years) with normal cardiac anatomy, function, and atrioventricular node conduction underwent echocardiography during electrophysiology studies while in sinus rhythm (NSR), and with temporary pacing from high right atrium (HRA), RAA, mid septal right atrium approximating Bachmann's bundle (BB), and left atrium (LA) via the distal coronary sinus (CS). After a paced steady state of 10 minutes, left atrial total and systolic ejection fractions, color-guided mitral inflow, and annular tissue Doppler indices were obtained. Left ventricular ejection fraction and myocardial performance indexes (MPI) were calculated.

RESULTS

The total and systolic LA ejection fractions were higher during the NSR compared to all ASAP. Mitral inflow velocities changed significantly with ASAP. The passive/active ventricular filling ratio (E/A) deteriorated from NSR to HRA to BB to CS. There were significant changes in late diastolic tissue Doppler velocities during ASAP compared to NSR. The MPI during ASAP differed from those during the NSR. HRA and Bachmann bundle pacing provided better MPIs than RAA or CS pacing.

CONCLUSION

The location of atrial pacing leads has an acute impact on cardiac function and atrioventricular mechanical interaction. Pacing close to sinus node location may be beneficial in the young.

Beat-to-beat change in "myocardial performance index" related to load

BACKGROUND

This study was designed to assess the relationship of the "myocardial performance index" (MPI) to the beat-by-beat change in pre-load with static or unchanged contractile status.

METHODS

Eight anesthetized juvenile pigs were studied using direct measurement of the left ventricular pressure and volume. Transient inflation of a vena cava balloon catheter produced controlled pre-load alterations. Consecutive beats were analyzed, grouped for first, second, third, etc. during the pre-load alteration, and evaluated for the change in MPI during the same contractile status with a controlled pre-load alteration. Two pharmacologic inotropic interventions were also included to generate several myocardial conditions in each animal.

RESULTS

MPI demonstrated a strong linear relationship to the pre-load and after-load. MPI increased progressively during decreasing end-diastolic volume, mostly related to changes in ejection time. MPI was observed at the same level for three different myocardial function conditions (all eight animals), with a different relationship between MPI and pre-load noted for each observation.

CONCLUSIONS

MPI is strongly load dependent, and can vary widely in value for the same contractile status if the load is varied. The use of this index in critically ill patients should be limited in this respect. Further work is needed to establish the relationship of MPI to load and contractile status.

Relationship between tissue Doppler-derived RV systolic function and invasive hemodynamic measurements

Tissue Doppler imaging (TDI) is effective in assessing right ventricular (RV) function, but the relationship between invasive measurements and RV-TDI remains unclear. We investigated the RV systolic function by using the TDI-derived systolic myocardial (Sa) velocity and myocardial performance index (MPI). Beagles (n = 7) were anesthetized in the right lateral recumbent position. A 3.5-Fr micromanometer-tipped catheter was placed in the RV to determine the hemodynamic changes. Dobutamine (5.0 and 10 microg.kg(-1).min(-1)) and esmolol (50 and 100 microg.kg(-1).min(-1)) were infused intravenously. Pulsed Doppler (PD) and TDI measurements were performed in the apical four-chamber view. Compared with baseline, the PD-MPI decreased significantly with the dobutamine infusion at 5 microg.kg(-1).min(-1) (P < 0.05). Both dobutamine infusions significantly decreased the TDI-MPI (P < 0.01, P < 0.05). Esmolol increased the PD- and TDI-MPI but not significantly. Dobutamine significantly increased the Sa velocity (both P < 0.001), whereas esmolol had no effect. The Sa velocity was strongly correlated with the peak positive derivative of the RV pressure (+dP/dt; r = 0.93). The negative correlation between the +dP/dt and TDI-MPI (r = -086) was greater that with the PD-MPI (r = -0.54). Stepwise regression analysis showed that the Sa velocity and PD-derived isovolumic contraction time were identified to predict the +dP/dt (r = 0.94, r(2) = 0.89; P < 0.001). We determined that the systolic myocardial velocity and TDI-MPI were strongly correlated with the RV contractility. These results suggest that the TDI-derived systolic myocardial velocity and MPI predict RV systolic function.

Septal pacing preserving better left ventricular mechanical performance and contractile synchronism than apical pacing in patients implanted with an atrioventricular sequential dual chamber pacemaker

BACKGROUND

Permanent pacing is the treatment for chronotropically incompetent hearts. However, the right ventricular (RV) apical pacing-induced asynchrony, even maintaining the atrioventricular (AV) sequential activation, has depressed left ventricular contractility. Whether RV septal pacing would less compromise the electromechanical performance of the left ventricle and the chronotropic effect on myocardial contractility, is unknown.

METHODS

We prospectively studied 42 patients without structural heart diseases and with symptomatic bradycardia. There were 10 patients receiving atrial pacing (AAI) pacemakers, 18 patients having AV sequential pacing at RV apex (DDDapx) and 14 patients being AV sequentially paced at septum (DDDspt). Echocardiography was performed before and within 72 h after the pacemaker implantation. The ventricular mechanical performance and asynchrony was compared in conditions of programmed rates of 60, 80 and 100/min.

RESULTS

Myocardial performance index was significantly better in DDDspt than in DDDapx patients (p=0.003). With faster programmed rate, the QRS/RR increased (p<0.05) in DDDapx patients with more inter- and intraventricular asynchrony, implicating the disadvantage of prolonged depolarization time. The DDDspt group demonstrated comparable parameters of diastolic function to AAI patients and preserved mechanical performance during accelerated pacing.

CONCLUSIONS

RV septal pacing showed the advantages of shorter depolarization time, less ventricular contractile asynchrony, better mechanical performance and preserved chronotropic response on myocardial contractility in comparison with apical pacing.