Usefulness of Doppler tissue imaging for the assessment of right and left ventricular myocardial function in patients with dual-chamber pacing

Comparison between IEGM-based approach and echocardiography in AV/PV and VV delay optimization in CRT-D recipients (Quicksept study)

BACKGROUND

AtrioVentricular (AV) and InterVentricular (VV) delay optimization can improve ventricular function in Cardiac Resynchronization Therapy (CRT) and is usually performed by means of echocardiography. St Jude Medical has developed an automated algorhythm which calculates the optimal AV and VV delays (QuickOpt™) based on Intracardiac ElectroGrams, (IEGM), within 2 min. So far, the efficacy of the algorhythm has been tested acutely with standard lead position at right ventricular (RV) apex. Aim of this project is to evaluate the algorhythm performance in the mid- and long-term with RV lead located in mid-septum.

METHODS

AV and VV delays optimization data were collected in 13 centers using both echocardiographic and QuickOpt™ guidance in CRTD implanted patients provided with this algorhythm. Measurements of the aortic Velocity Time Integral (aVTI) were performed with both methods in a random order at pre-discharge, 6-month and 12-month follow-up.

RESULTS

Fifty-three patients were studied (46 males; age 68 ± 10y; EF 28 ± 7%). Maximum aVTI obtained by echocardiography at different AV delays, were compared with aVTI acquired at AV delays suggested by QuickOpt. The AV Pearson correlations were 0.96 at pre-discharge, 0.95 and 0,98 at 6- and 12- month follow-up respectively. After programming optimal AV, the same approach was used to compare echocardiographic aVTI with aVTI corresponding to the VV values provided by QuickOpt. The VV Pearson Correlation were 0,92 at pre-discharge, 0,88 and 0.90 at 6-month and 12- month follow-up respectively.

CONCLUSIONS

IEGM-based optimization provides comparable results with echocardiographic method (maximum aVTI) used as reference with mid-septum RV lead location.

Early diastolic peak velocity of left ventricular wall segment lying in isovolumic relaxation period as determined by tissue Doppler imaging

BACKGROUND

The early diastolic peak velocity of left ventricular (LV) wall segment has always been regarded as appearing in the rapid filling phase. However, we find some segments of which early diastolic peak velocities appear in the isovolumic relaxation period (PVIVR segments). The present study aimed to investigate the characteristics of PVIVR segments.

METHODS

Tissue Doppler imaging was performed in each of the 16 segments of LV wall in 99 patients with known or suspected coronary heart disease and 50 normal subjects. Early diastolic velocity pattern was classified as PVIVR, post-systolic shortening (PSS) and normal pattern.

RESULTS

The multivariate logistic regression analyses showed that the significant echocardiographic predictors of the presence of PVIVR in a patient were transmitral E/A ratio and isovolumic relaxation time. Segmental early diastolic velocity pattern was significantly associated with actual coronary stenosis, relative coronary stenosis and wall motion score. PVIVR segments had a lower early diastolic peak velocity than other segments.

CONCLUSION

PVIVR segments more frequently appear in the territory with the relatively mildest coronary stenosis, whereas PSS segments more frequently appear in the territory with the relatively most severe coronary stenosis. Patients with PVIVR have lower global LV diastolic function. A decreased early diastolic peak velocity of PVIVR segments does not necessarily mean impaired myocardial relaxation.

Effect of Heart Rate on Tissue Doppler Measures of Diastolic Function

BACKGROUND

Our aim was to study the independent effect of heart rate (HR) on parameters of diastolic function, particularly mitral annular velocities measured by tissue Doppler imaging (TDI), an effect which is not well understood.

METHODS

Sixteen patients with dual chamber pacemakers attending for routine pacemaker review underwent detailed echocardiographic assessment during atrial pacing with intact atrioventricular conduction at baseline and accelerated HRs. Mitral inflow and annular tissue Doppler velocities and systolic strain parameters were compared.

RESULTS

Parameters of systolic function were unaffected by increased HR. When these parameters were compared at baseline (mean 67 bpm) and accelerated HR (mean 80 bpm), the following was observed: a significant decrease in early mitral inflow (E) wave (70.5 +/- 5.5 cm/s vs 63.5 +/- 4.9 cm/s, P < 0.02) and early mitral annular (E') velocities (7.0 +/- 0.5 cm/s vs 6.3 +/- 0.6 cm/s, P < 0.003) and a significant increase in mitral inflow A wave (70.3 +/- 4.5 cm/s vs 77.3 +/- 4.4 cm/s, P < 0.05) and late mitral annular (A') velocities (9.3 +/- 0.6 cm/s vs 10.8 +/- 0.5, P < 0.00004).

CONCLUSION

Changes in HR have previously unrecognized significant effects on tissue Doppler parameters of diastolic function. Further study is required to determine if tissue Doppler derived annular velocities should be corrected for HR.

Towards an understanding of the mechanics underlying aortic dissection

Acute aortic dissection and associated aortic catastrophes are among the most devastating forms of cardiovascular disease, with a remarkably high morbidity and mortality despite current medical and surgical treatment. The mechanics underlying aortic dissection are incompletely understood, and a further understanding of the relevant fluid and solid mechanics may yield not only a better appreciation of its pathogenesis, but also the development of improved diagnostic and therapeutic strategies. After illustrating some of the inadequacies with respect to the extant work on the mechanics of aortic dissection, we alternatively postulate that the clinical hemodynamic disturbances that render the aorta susceptible to the initiation of dissection are principally elevated maximum systolic and mean aortic blood pressure, whereas the hemodynamic disturbances that facilitate propagation of dissection are principally elevated pulse pressure and heart rate. Furthermore, abnormal aortic mechanical properties and/or geometry are requisite for dissection to occur. Specifically, we propose that the degree of anisotropy will directly influence the probability of future aortic dissection. Imaging of the aorta may provide information regarding aortic anisotropy and geometry, and in combination with a hemodynamic risk assessment, has the potential to be able to prospectively identify patients at high risk for future aortic dissection thereby facilitating prophylactic intervention. The aim of the paper is to identify the main mechanical issues that have a bearing on aortic dissection, and to suggest an appropriate mathematical model for describing the problem.

Quantifying regional right ventricular function in tetralogy of Fallot

Right ventricular (RV) function is notoriously difficult to quantify. Patients with tetralogy of Fallot (TOF) have decreased systolic performance. We measure regional RV performance using MRI with 1-dimensional myocardial tissue tagging. By tagging cine-MRI in two views, we measured regional shortening in 12 regions throughout the RV. We image 32 pediatric patients: 21 normal patients and 11 patients with repaired TOF. We establish a normal range for each RV region. TOF patients have decreased shortening on a region-by-region basis. We conclude that regional RV performance can be measured using this technique, and that decreased performance can be demonstrated in TOF patients.

Myocardial Systolic Activation Delay in Patients with Left Bundle Branch Block and Either Normal or Impaired Left Ventricular Function

AIM OF THE STUDY

to evaluate determinants of myocardial activation delay of both left (LV) and right (RV) ventricle in patients with left bundle branch block (LBBB) and either normal or impaired LV ejection fraction (EF).

METHODS

From an initial cohort of patients with LBBB, 42 patients with dilated cardiomyopathy (group A) and 33 with normal global LV systolic function (group B), all comparable in age and sex, underwent standard Doppler echo, pulsed Doppler myocardial imaging (DMI), and coronary angiography. Using DMI, the following regional parameters were evaluated in five different basal myocardial segments (LV anterior, inferior, septal, lateral walls-RV lateral wall): systolic (Sm), early- and late-diastolic (Em and Am) peak velocities. As index of myocardial systolic activation was calculated: precontraction time (PCTm) (from the beginning of Q-wave of ECG to the onset of Sm). Intraventricular systolic dyssynchrony was analyzed by difference of PCTm in different LV myocardial segments. Interventricular activation delay was calculated by the difference of PCTm between the most delayed LV segment and RV lateral wall.

RESULTS

Patients of group A showed increased heart rate (HR), QRS duration and LV end-diastolic diameter, and reduced LV EF. By DMI, patients of group A showed reduced myocardial peak velocities and a significant intraventricular delay in activation of LV lateral wall, with increased regional PCTm (P < 0.001). In addition, patients with dilated cardiomyopathy showed a more pronounced interventricular dyssynchrony, even after adjustment for HR and QRS duration. By receiver operating characteristic (ROC) curve analysis, a cut-off value of 55 msec of interventricular delay showed 86% sensitivity and 92% specificity in identifying patients with impaired EF. In the overall population, by use of stepwise forward multivariate linear regression analyses, LV end-diastolic diameter (beta coefficient = 0.52; P < 0.001) and LV EF (beta coefficient =-0.58; P < 0.0001) were the only independent determinants of interventricular activation delay.

CONCLUSIONS

Pulsed DMI is an effective noninvasive technique for assessing the severity of regional delay in activation of LV walls in patients with LBBB. The impairment of interventricular systolic sychronicity is strongly related to LV dilatation and to the degree of global systolic dysfunction. Therefore, patients with dilated cardiomyopathy suitable for cardiac resynchronization therapy may be better selected.

Right ventricular myocardial dysfunction in adult patients late after repair of tetralogy of fallot

AIM OF THE STUDY

To detect in adult patients late after repair of Tetralogy of Fallot (TOF) possible correlation between myocardial parameters assessed at rest by Tissue Doppler (TD) and cardiac performance during physical effort.

METHODS

Doppler echo, treadmill test and pulsed TD of both mitral and tricuspid annulus were performed in 25 healthy subjects and in 40 adult patients who had undergone surgery for TOF at a mean age of 1.4+/-0.5 years. Exclusion criteria were echocardiographic evidence of residual pulmonary, either stenosis or regurgitation. By use of TD, the following parameters were assessed: systolic peak velocities (Sm), pre-contraction time, contraction time, early (E(m)) and late (A(m)) diastolic velocities, E(m)/A(m) ratio, relaxation time. By treadmill test, we measured: maximal heart rate (HR), systolic blood pressure (SBP), rate-pressure product, maximal workload, time duration of the exercise.

RESULTS

the two groups were comparable for left ventricular measurements and for all transmitral and transtricuspid Doppler indexes, while tricuspid ring diameter was increased in TOF. TD analysis showed in TOF lower S(m), E(m) and E(m)/A(m) ratio and prolonged PCT(m) and Rt(m) at tricuspid annulus level, despite comparable TD mitral annulus indexes. By treadmill test, TOF showed reduced time of exercise, number of METS reached and rate-pressure product. Multiple linear regression models evidenced in TOF independent positive association between tricuspid Em velocity and time of exercise (p<0.0001), achieved METS at peak effort (p<0.001) and rate-pressure product (p<0.001). An E(m) peak velocity of tricuspid annulus lower than 0.13 m/s showed 90% sensitivity and 93% specificity in identifying TOF patients unable to perform maximal exercise test.

CONCLUSIONS

despite normal Doppler parameters, adult patients late after correction of TOF showed impaired right ventricular myocardial function. In these patients pulsed TD may be taken into account as a valuable supporting tool to predict the effort response and possibly to assess long-term follow-up of cardiac functional reserve.

Different involvement of right ventricular myocardial function in either physiologic or pathologic left ventricular hypertrophy: a Doppler tissue study

The aim of the study was to analyze right ventricular (RV) myocardial function in patients with left ventricular (LV) hypertrophy secondary to either hypertrophic cardiomyopathy (HC) or athletic endurance training. Doppler echocardiography and pulsed Doppler tissue imaging of the posterior septal wall, and mitral and tricuspid annulus were performed in 32 top-level endurance athletes (AT) and in 27 patients with HC, all men. LV mass index was comparable between the 2 groups. All transmitral Doppler indexes were higher in AT, whereas only tricuspid inflow peak E and E/A ratio were slightly decreased in the HC group. In the HC group, Doppler tissue analysis showed lower myocardial systolic and early-diastolic (Em) peak velocities, and longer time intervals at the level of all the analyzed segments, even after correction for age, heart rate, and LV mass index. Distinct multiple linear regression models revealed an independent positive association between RV peak Em velocity and LV end-diastolic diameter (beta coefficient = 0.72, P <.0001) in AT, and an independent inverse correlation of the same peak Em velocity of tricuspid annulus with septal thickness (beta = - 0.65, P <.001) in the HC group. Of interest, a RV Em peak velocity < 0.16 m/s differentiated AT and HC groups better than tricuspid Doppler (89% sensitivity and 93% specificity). In conclusion, Em RV myocardial function is positively influenced by preload increase in AT and negatively associated to increased septal thickness in patients with HC. Therefore, Doppler tissue imaging may represent a useful tool in the differential diagnosis between athlete's heart and HC, underlining the different involvement of RV myocardial function in either physiologic or pathologic LV hypertrophy.