Dynamic left ventricular dyssynchrony contributes to B-type natriuretic peptide release during exercise in patients with systolic heart failure

Aims: Plasma B-type natriuretic peptide (BNP) is an emerging biomarkerin heart failure. In this setting, the extent of left ventricular(LV) dyssynchrony contributes to exercise symptoms. Whetherexercise-induced changes in LV dyssynchrony might be a triggerof BNP release has never been investigated. Methods and results: Fifty-seven patients with systolic LV dysfunction underwentquantitative analysis of BNP, mitral regurgitation (MR), anddyssynchrony at rest and during exercise. None had inducibleischaemia on perfusion imaging. By multiple regression analysis,end-systolic volume index (P < 0.0001), effective regurgitantorifice (ERO) (P < 0.001), and E/Ea (P = 0.002) emerged asindependent determinants of BNP at baseline (R² = 0.67). Exerciseinduced a significant rise in BNP levels (P < 0.0001). Inmultivariate analysis, a smaller change in systolic blood pressure(P = 0.04), a larger increase in ERO (P = 0.017), and in systolicdyssynchrony index (P = 0.006) during exercise emerged as independentdeterminants of exercise-induced increases in BNP (R² = 0.45). Conclusion: MR severity, volume overload, and LV filling pressure are surrogatesof BNP at rest. During exercise, changes in BNP reflect thepresence of dynamic changes in both LV dyssynchrony and MR severityin the absence of inducible ischaemia.     

Mechanism of improvement in mitral regurgitation after cardiac resynchronization therapy.

AIMS: The aim of the current study was to evaluate the relationship between the presence of left ventricular (LV) dyssynchrony at baseline and acute vs. late improvement in mitral regurgitation (MR) after cardiac resynchronization therapy (CRT). METHODS AND RESULTS: Sixty eight patients consecutive (LV ejection fraction 23 +/- 8%) with at least moderate MR (>or=grade 2+) were included. Echocardiography was performed at baseline, 1 day after CRT initiation and at 6 months follow-up. Speckle tracking radial strain was used to assess LV dyssynchrony at baseline. The majority of patients improved in MR after CRT, with 43% improving immediately after CRT, and 20% improving late (after 6 months) after CRT. Early and late responders had similar extent of LV dyssynchrony (209 +/- 115 ms vs. 190 +/- 118 ms, P = NS); however, the site of latest activation in early responders was mostly inferior or posterior (adjacent to the posterior papillary muscle), whereas the lateral wall was the latest activated segment in late responders. CONCLUSION: Current data suggest that the presence of baseline LV dyssynchrony is related to improvement in MR after CRT. LV dyssynchrony involving the posterior papillary muscle may lead to an immediate reduction in MR, whereas LV dyssynchrony in the lateral wall resulted in late response to CRT.     

The Relationship Between Aortic Stiffness and Left Ventricular Dyssynchrony in Hypertensive Patients with Preserved Left Ventricular Systolic Function

Left ventricular (LV) dyssynchrony is often seen in patients with hypertension, even without heart failure. Arterial stiffness is well accepted as an important factor of increasing blood pressure and influencing ventricular function. The purpose of this study was to determine the relationship between aortic stiffness and LV dyssynchrony in hypertensive patients with preserved LV systolic function. Eighty hypertensive patients with preserved LV systolic function (LV ejection fraction > 50%) and 30 controls were studied. The LV systolic and diastolic dyssynchrony indices were determined as the standard deviation of the time interval from onset of the QRS complex to peak myocardial systolic velocity (Ts-SD) and to early diastolic velocity (Te-SD) and the maximal differences in Ts (Ts-Max) and Te (Te-Max) in 12 LV segments. Aortic stiffness index was calculated from aortic diameters in the systolic and diastolic phases, as measured by echocardiography and blood pressure. No relationship was observed between LV systolic and diastolic dyssynchrony indices (r = 0.057, P = .61). In simple regression, aortic stiffness parameter was related to left ventricular mass index (LVMI), E/A ratio, and LV diastolic dyssynchrony index. But using multiple linear regression, Te-Max remained as a single variable related to aortic strain and aortic stiffness index (r = ?0.271, P = .008 and r = 0.269, P = .008). LVMI was related to aortic distensibility using multiple linear regression (r = ?0.239, P = .02). Aortic stiffness index was related to LV diastolic dyssynchrony index and LVMI. These findings suggest that LV diastolic dyssynchronous changes may be caused by increased LV mass and arterial stiffness.     

Acute Effects of Multisite Left Ventricular Pacing on Mechanical Dyssynchrony in Patients Receiving Cardiac Resynchronization Therapy

BackgroundA novel quadripolar left ventricular (LV) pacing lead has the ability to deliver multisite LV pacing (MSLV). We set out to characterize the safety and changes in acute mechanical dyssynchrony with MSLV in cardiac resynchronization therapy (CRT) patients.Methods and ResultsProspective multicenter study in 52 patients receiving CRT. An acute pacing protocol comprising 8 MSLV configurations covering a range of delays was compared with conventional CRT (baseline). Transthoracic tissue Doppler imaging (TDI) was used to measure the standard deviation of time to peak contraction of 12 LV segments (Ts-SD) and delayed longitudinal contraction. No ventricular arrhythmia occurred in any of the 52 patients. Complete TDI datasets were collected in 41 patients. Compared with baseline: 1) The mean Ts-SD was significantly lower for the optimal MSLV configuration (35.3 ± 36.4 vs 50.2 ± 29.1 ms; P < .001); 2) at least 1 MSLV configuration exhibited a significant dyssynchrony improvement in 63% of patients; and 3) the mean number of LV segments with delayed longitudinal contractions was significantly reduced with the optimal MSLV configuration (0.37 ± 7.99 vs 2.20 ± 0.19; P < .001).ConclusionsAcute MSLV was acutely safe, and a proportion of MSLV vectors resulted in a significant reduction in echocardiographic dyssynchrony compared with conventional CRT.     

Cardiac Resynchronization Therapy

Cardiac resynchronization therapy (CRT) is a recently developed approach to treat dilated heart failure with discoordinate contraction. Such dyssynchrony typically stems from electrical delay that then translates into mechanical delay between the septal and lateral walls. Over the past decade, many studies have examined the pathophysiology of cardiac dyssynchrony, tested the effects of cardiac resynchronization on heart function and energetics,tested the chronic efficacy of this therapy to enhance symptoms and reduce mortality, and better established which patients are most likely to benefit. This brief review discusses these topics.     

Left posterior hemiblock related to an interventricular septum tumour. First case in the literature.

A 22-year-old man who engaged in intense and regular physical exercise complained of atypical chest pain. The only remarkable abnormality found in the routine clinical work-up was a left posterior hemiblock. The echocardiogram and the magnetic resonance imaging (MRI) study showed a tumour in the posterior and superior aspect of the interventricular septum where the posterior fascicle of the left bundle is located. It was interpreted that the left posterior hemiblock was produced by the tumour.     

Fatal acute left ventricular outflow obstruction due to interventricular septal haematoma -- diagnosis by transoesophageal echocardiography

We describe a case of fatal left ventricular outflow obstructiondetected by intraoperative transoesophageal echocardiography.This resulted from acute haematoma formation within the interventricularseptum follow–ing internal mammary artery grafting tothe left anterior descending coronary artery. This unusual casehighlights the emerging role of transoesophageal echocardiographyin the diagnosis and management of the complications of cardiacsurgery.