BACKGROUNDRight ventricular apical pacing has been reported to reduce cardiac performance. But there are few reports on the effects of dual chamber (DDD) pacing on cardiac function compared to sinus rhythm. In this study, we evaluated the effects of right atrial and ventricular DDD pacing on cardiac function and ventricular contraction synchrony using equilibrium radionuclide angiography.

METHODSTen patients implanted with a right atrial and ventricular DDD pacemaker underwent equilibrium radionuclide angiography. The scintigraphic data were obtained during sinus rhythm and pacing rhythm. Cardiac function parameters were obtained semimanually. Phase analysis was used to study the ventricular activation sequence and ventricular synchrony.

RESULTSThe left ventricular 1/3 ejection fraction decreased significantly during pacing compared with that during sinus rhythm [(23.4 +/- 6.1)% vs (27.7 +/- 4.5)%, P = 0.01]. Regional ejection fraction also decreased during pacing, although the difference was not statistically significant. Phase analysis showed that the right ventricle was activated earlier than the left ventricle during pacing, and that the phase shift was significantly greater during pacing than that during sinus rhythm [64.13 degrees +/- 16.80 degrees vs 52.88 degrees +/- 9.26 degrees, P = 0.007]. The activation of both ventricles occurred simultaneously during sinus rhythm, with the activation sequence from proximal septum or base of left ventricle to apex. The earliest activation during pacing occurred at the right ventricular apex, and subsequently spread to the base and left ventricle.

CONCLUSIONRight atrial and ventricular DDD pacing impairs left ventricular systolic function and ventricular synchrony.

Cardiac Pacing, Artificial ; Humans ; Myocardial Contraction ; Systole ; Ventricular Function, Left

BACKGROUND/AIMS: The aim of this study was to identify changes in left ventricular (LV) performance in patients with a myocardial bridge (MB) in the left anterior descending coronary artery during resting and in an inotropic state. METHODS: Myocardial strain measurement by speckle-tracking echocardiography and conventional LV wall-motion scoring was performed in 18 patients with MB (mean age, 48.1 +/- 1.7 years, eight female) during resting and intravenous dobutamine challenge (10 and 20 microg/kg/min). RESULTS: Conventional LV wall-motion scoring was normal in all patients during resting and in an inotropic state. Peak regional circumferential strain increased dose dependently upon dobutamine challenge. Longitudinal strains of the anterior and anteroseptal segments were, however, reduced at 20 microg/kg/min and showed a dyssynchronous pattern at 20 microg/kg/min. Although there were no significant differences in radial strain and displacement of all segments at rest compared with under 10 microg/kg/min challenge, radial strain and displacement of anterior segments at 20 microg/kg/min were significantly reduced compared with posterior segments at the papillary muscle level (44.8 +/- 14.9% vs. 78.4 +/- 20.1% and 5.3 +/- 2.3 mm vs. 8.5 +/- 1.8 mm, respectively; all p < 0.001), and showed plateau (40%) or biphasic (62%) patterns. CONCLUSIONS: Reduced LV strain of patients with MB after inotropic stimulation was identified. Speckle-tracking strain echocardiography identified a LV myocardial dyssynchrony that was not demonstrated by conventional echocardiography in patients with MB.
Adrenergic beta-1 Receptor Agonists/*diagnostic use ; Adult ; Aged ; Chest Pain ; Coronary Angiography ; Diastole ; Dobutamine/*diagnostic use ; Echocardiography, Stress/instrumentation/*methods ; Female ; Humans ; Male ; Middle Aged ; *Myocardial Contraction ; *Myocardium ; Physical Exertion ; Systole ; *Ventricular Dysfunction, Left ; Ventricular Function, Left/*drug effects

OBJECTIVETo evaluate the myocardial systolic function and ventricular remodeling in heart failure rat induced by myocardial infarction (MI) with S/SRI and MMP-9.

METHODSA total of 70 male SD rats were randomly assigned to 4 groups: 4 weeks and 8 weeks MI (anterior descending branch of left coronary artery were ligated), sham operation (thoracotomy without ligation of coronary artery) and non-operated control group. The regional myocardial systolic function of rats was quantified with S/SRI. The myocardial MMP-9 expression was detected by Western blot.

RESULTSIn the 4 weeks MI group, all segment's Ssys, SRsys, the strain of end-systole were reduced while PSI was increased compared to sham and non-operated group with the exception of the inferior wall. These changes were more significant in 8 weeks MI group compared to the 4 weeks MI group. In the 4 weeks MI group, the expression of MMP-9 was significantly upregulated than the sham operation group and this upregulation was more significant at 8 weeks post MI.

CONCLUSIONSS/SRI can quantitative evaluate the regional systolic function of heart failure rat induced by myocardial infarction. Progressive upregulation of myocardial MMP-9 expression paralleled the deterioration of regional systolic function in this heart failure rat model.

Animals ; Heart Failure ; metabolism ; physiopathology ; Male ; Matrix Metalloproteinase 9 ; metabolism ; Myocardial Contraction ; Myocytes, Cardiac ; metabolism ; Rats ; Rats, Sprague-Dawley ; Systole ; Ventricular Remodeling

OBJECTIVETo evaluate intraventricular mechanical synchrony in systole by real-time tri-plane tissue synchronization imaging (TSI).

METHODSReal-time tri-plane TSI was performed in 20 normal subjects, and the apical 4-chamber, 2-chamber and long-axis views of the left ventricular (LV) were obtained simultaneously. The data were post-processed offline, and a TSI surface map of LV colorized according to the time-to-positive peak systolic velocity (TTP) was generated to reflect the segment TTP semi-quantitatively. The segmental TTP of the six-basal and six-mid segments of LV was measured and compared.

RESULTSThe myocardium was color-coded mainly by well-distributed green, and only a small portion displayed yellow or red color in the apical area; the TTP showed no significant differences between the segments measured (P>0.05).

CONCLUSIONSIn normal subjects, the long-axis systolic motions of the LV are highly synchronized. TSI allows immediate visual identification of intraventricular mechanical synchrony and quantitative measurement of regional TTP.

Adult ; Aged ; Echocardiography, Doppler, Color ; Female ; Heart Ventricles ; diagnostic imaging ; Humans ; Male ; Middle Aged ; Myocardial Contraction ; physiology ; Systole ; physiology ; Ventricular Function, Left ; Young Adult

Our study was aimed to evaluate the left ventricular (LV) global longitudinal systolic function of patients with diabetes mellitus (DM) using real-time three-plane speckle tracking imaging (RT-3P STI). The case group was the patients of type 2 DM with normal LV ejection fraction (EF). Then according to glycated hemoglobin (HbAlc) control level, the case group was divided into two groups, including DM1 (HbAlc<7%, n=31) and DM2 (HbAlc >or=7%, n= 37); 63 matched volunteers were chosen as control group. Conventional measurements of the LV size and function were performed. We then applied the automatic function imaging to analyze the global longitudinal systolic peak strain (GLPS) of the three apical views online, including the GLPS of apical four chamber view (GLPS-A4C), the GLPS of apical two chamber view (GLPS-A2C), the GLPS of apical long axis view (GLPS-LAX), and then generating the average GLPS (GLPS-Avg). The experimental results showed that there was no statistical difference in clinical baseline characteristics among the three groups (P>0.05). However, there were statistical differences in the ventricular wall thickness and the LV mass index of the DM1 and DM2 groups compared with that of the control (P<0. 05). No significant differences were found in LV diameters, volumes, LVEF among the three studied groups (P>0. 05). We also found significant differences in GLPS-LAX, GLPS-A2C, GLPS-Avg when we compared DM2 group with those of the DM1 group or the control (P<0. 05). We found a statistical difference in GLPS-A4C only when we compared the DM2 group with the control(P<0. 05), and no statistical difference in the strains of the three views between DM1 group and control (P>0. 05). RT-3P STI could not only accurately be used to evaluate the LV global longitudinal systolic function, but could also reflect the reduction of sub-clilical systolic function in DM patients with poor blood glucose control in the early stage.
Aged ; Case-Control Studies ; Diabetes Mellitus, Type 2 ; complications ; diagnostic imaging ; physiopathology ; Echocardiography, Three-Dimensional ; methods ; Female ; Heart Ventricles ; diagnostic imaging ; Humans ; Male ; Middle Aged ; Myocardial Contraction ; physiology ; Stroke Volume ; Systole ; Ventricular Dysfunction, Left ; diagnostic imaging ; etiology ; Ventricular Function, Left

To evaluate the effects of left ventricular contractility on the changes of average image intensity (AII) of the myocardial integrated backscatter (IB) and cyclic variation in IB (CVIB), 7 adult mongrel dogs were studied. The magnitude of AII and CVIB were measured from myocardial IB carves before and after dobatamine or propranolol infusion. Dobutamine or propranolol did not affect the magnitude of AII (13.8 +/- 0.7 vs 14.7 +/- 0.5, P > 0.05 or 14.3 +/- 0.5 vs 14.2 +/- 0.4, P > 0.05). However, dobutamine produced a significant increase in the magnitude of CVIB (6.8 +/- 0.3 vs 9.5 +/- 0.6, P < 0.001) and propranolol induced significant decrease in the magnitude of CVIB (7.1 +/- 0.2 vs 5.2 +/- 0.3, P < 0.001). The changes of the magnitude of AII and CVIB in the myocardium have been demonstrated to reflect different myocardial physiological and pathological changes respectively. The alteration of contractility did not affect the magnitude of AII but induced significant change in CVIB. The increase of left ventricular contractility resulted in a significant rise of the magnitude of CVIB and the decrease of left ventricular contractility resulted in a significant fall of the magnitude of CVIB.
Adrenergic beta-Agonists ; pharmacology ; Adrenergic beta-Antagonists ; pharmacology ; Animals ; Coronary Circulation ; Dobutamine ; pharmacology ; Dogs ; Echocardiography ; methods ; Hemodynamics ; drug effects ; Myocardial Contraction ; drug effects ; physiology ; Propranolol ; pharmacology ; Systole ; Ventricular Function, Left ; physiology

OBJECTIVETo evaluate the relationship between myocardial systolic, diastolic functions and perfusion in coronary artery stenosis using velocity vector imaging (VVI) and myocardial contrast echocardiography (MCE).

METHODSStenoses in the anterior descending branch of the coronary artery were induced in 8 dogs. Before and after coronary artery stenosis, two-dimensional images of the left ventricular mastoid muscle section on the short axis at rest and in the peak dose of dobutamine were obtained for evaluation of VVI and MCE. The myocardial blood flow A.beta values, peak systolic strain rate (SRsys) and peak diastolic strain rate (SRdia) in the direction of the circumference of the short axis were measured.

RESULTSAt rest, only severe coronary stenosis resulted in significantly lowered SRsys, SRdia and A.beta value of the stenotic bed compared to the values before the stenosis (-1.1-/+0.50 vs -1.62-/+0.50, 1.19-/+0.48 vs 1.75-/+0.51, 0.4-/+0.21 vs 0.80-/+0.47, P<0.05). In stress, SRsys, SRdia and A.beta value of the stenotic bed gradually decreased as coronary stenosis worsened (-4.31-/+1.14 vs -3.20-/+0.98 vs -1.18-/+0.64, 4.51-/+1.13 vs 3.39-/+0.98 vs 1.37-/+0.64. 3.54-/+1.95 vs 1.81-/+0.89 vs 0.82-/+0.42, P<0.05). Both at rest and in stress, good correlations were noted between SRsys and SRdia (r(rest)=0.88, r(stress)=0.96, P<0.01), between SRsys and the standard A.beta values (r(rest)0.56, r(stress)=0.71, P<0.01), and between SRdia and A.beta (r(rest)=0.57, r(stress)=0.72, P<0.01) in the direction of the circumference of the short axis.

CONCLUSIONSUsing VVI and MCE, the changes in myocardial perfusion and the systolic and diastolic functions in the direction of the circumference can be observed dynamically. VVI may help assess the condition of myocardial perfusion by evaluating the systolic and diastolic function.

Animals ; Blood Flow Velocity ; physiology ; Coronary Circulation ; Coronary Stenosis ; complications ; diagnostic imaging ; physiopathology ; Diastole ; Dogs ; Echocardiography ; methods ; Female ; Male ; Myocardial Contraction ; Ventricular Dysfunction, Left ; diagnostic imaging ; etiology ; physiopathology ; Ventricular Function, Left ; physiology

BACKGROUND AND OBJECTIVES: Although the Tei index is a useful predictor of global ventricular function, it has not been investigated at the level of regional myocardial function. We therefore investigated the segmental tissue Doppler image derived-Tei index (TDI-Tei index) in patients with regional wall motion abnormalities. SUBJECTS AND METHODS: We prospectively studied 17 patients (mean age 62+/-9 years, 5 women) with left ventricular (LV) regional wall motion abnormalities. The Tei index, defined as the sum of isovolumetric contraction time (IVCT) and isovolumetric relaxation time (IVRT) divided by ejection time (ET), was measured in the basal and mid segments of the LV walls from standard apical views (4-, 2-, and 5-chamber views). We also obtained TDI velocity data in each segment. LV wall motion was classified as normal, hypokinetic, or akinetic, based on visual analysis. The TDI-Tei index, peak systolic myocardial velocity (Sm), early diastolic myocardial velocity (Em), and late diastolic myocardial velocity (Am) were analyzed in a total of 203 segments. RESULTS: Mean LV ejection fraction was 41.8+/-8.5%. TDI-Tei indices of dysfunctional segments (akinesis or hypokinesis, n=63) were significantly higher than those of normal segments (n=140) (0.714+/-0.169 vs. 0.669+/-0.135, p=0.041, respectively). Average values of TDI-Tei index, Sm, Em, and Am were 0.742+/-0.201, 4.206+/-1.336, 5.258+/-1.867, and 5.578+/-2.354 in akinetic segments; 0.677+/-0.101, 4.908+/-1.615, 5.369+/-2.121, and 5.542+/-2.492 in hypokinetic segments; and 0.669+/-0.135, 5.409+/-1.519, 6.108+/-2.356, and 6.719+/-2.466 in normal segments, respectively. A significant negative correlation was apparent between the TDI-Tei index and Sm (r=-0.302, p<0.001). CONCLUSION: These data suggest that the value of the segmental TDI-Tei index differs significantly according to regional function grade.
Contracts ; Humans ; Myocardial Contraction ; Prospective Studies ; Relaxation ; Ventricular Function

BACKGROUND/AIMS: Increased left atrial (LA) size has been proposed as a predictor of poor cardiovascular outcome in the elderly. In the present study, we evaluated the relationship between LA size and stroke in subjects of all ages who presented with preserved left ventricular systolic function (LVSF) and sinus rhythm (SR), and investigated the relationships between LA size and other echocardiographic parameters of diastolic function. METHODS: A total of 472 subjects were enrolled in the study (161 men, 311 women) and divided into the stroke group (n=75) and control group (n=397). A conventional echocardiographic study was then performed. Subjects with valvular heart disease, atrial fibrillation, or coronary heart disease were excluded. RESULTS: The mean subject age was 65.2+/-5.1 years in the stroke group and 65.6+/-5.9 years in the control group. Mitral inflow pattern and E & A velocity showed no significant relationship with stroke (p=NS, p=NS, respectively). Left ventricular mass index and LA dimension were significantly related to stroke (p=0.003, p=0.023, respectively), and hypertension showed a marginal relationship with stroke (p=0.050). Age was not related to stroke in the present study (p=NS). CONCLUSIONS: The LA dimension is significantly related to the incidence of stroke. Therefore, strategies for prevention of stroke in patients with preserved LVSF and SR should be considered in cases of LA enlargement.
Adult ; Aged ; Echocardiography, Doppler, Pulsed ; Female ; Heart Atria/*ultrasonography ; Heart Rate/*physiology ; Heart Ventricles/physiopathology/ultrasonography ; Humans ; Incidence ; Korea/epidemiology ; Male ; Middle Aged ; Myocardial Contraction/*physiology ; Retrospective Studies ; Risk Factors ; Stroke/*epidemiology/etiology ; Stroke Volume/*physiology ; Systole ; Ventricular Function, Left/*physiology

This study evaluated the application of quantitative tissue velocity imaging (QTVI) in assessing regional myocardial systolic and diastolic functions in dogs with acute subendocardial ischemia. Animal models of subendocardial ischemia were established by injecting microspheres (about 300 microm in diameter) into the proximal end of left circumflex coronary artery in 11 hybrid dogs through cannulation. Before and after embolization, two-dimensional echocardiography, QTVI and real-time myocardial contrast echocardiography (RT-MCE) via intravenous infusion of self-made microbubbles, were performed, respectively. The systolic segmental wall thickening and subendocardial myocardial longitudinal velocities of risk segments before and after embolization were compared by using paired t analysis. The regional myocardial video intensity versus contrast time could be fitted to an exponential function: y=A.(1-exp(-beta.t)), in which the product of A and beta provides a measure of myocardial blood flow. RT-MCE showed that subendocardial normalized A.beta was decreased markedly from 0.99+/-0.19 to 0.35+/-0.11 (P<0.05) in 28 left ventricular (LV) myocardial segments after embolization, including 6 basal and 9 middle segments of lateral wall (LW), 8 middle segments of posterior wall (PW) and 5 middle segments of inferior wall (IW). However, there was no statistically significant difference in subepicardial layer before and after embolization. Accordingly, the ratio of A.beta of subendocardial myocardium to subepicardial myocardium in these segments was significantly decreased from 1.10+/-0.10 to 0.31+/-0.07 (P<0.05). Although the systolic wall thickening did not change 5 min after the embolization in these ischemic segments (29%+/-3% vs 31%+/-5%, P>0.05), the longitudinal peak systolic velocities (Vs) and early-diastolic peak velocities (Ve) recorded by QTVI were declined significantly (P<0.05). Moreover, the subendocardial velocity curves during isovolumic relaxation predominantly showed positive waves, whereas they mainly showed negative waves before the embolization. This study demonstrates that QTVI can more sensitively and accurately detect abnormal regional myocardial function and post-systolic systole caused by acute subendocardial ischemia.
Contrast Media ; Echocardiography/*methods ; Endocardium/physiopathology ; Microbubbles ; Myocardial Contraction/physiology ; Myocardial Ischemia/etiology ; Myocardial Ischemia/*physiopathology ; Myocardial Ischemia/*ultrasonography ; Myocardium/pathology ; Ventricular Function, Left/*physiology