Effects of regional systolic asynchrony on left ventricular global diastolic function in patients with coronary artery disease

Three-dimensional echocardiographic evaluation of mechanical dyssynchrony in systolic heart failure with narrow QRS complex

Objectives

To investigate the role of three-dimensional echocardiography (3DE) in evaluation of left ventricular mechanical dyssynchrony (LVMD) in heart failure (HF) patients with narrow QRS.

Methods

143 subjects (70 with HF and narrow QRS, 23 with HF and LBBB and 50 controls) were subjected to 3DE, evaluating global and regional dyssynchrony using systolic dyssynchrony index, maximum segmental dyssynchrony and opposite segment dyssynchrony. Spatial distribution of LVMD was studied in each patient using 3DE derived regional time volume curves. Extent of LVMD in HF patients with narrow QRS was compared to those with left bundle branch block (LBBB).

Results

Frequency of LVMD was similar in HF patients with narrow QRS or LBBB (55.7% vs. 47.8%, p = NS). There was no difference in the severity of LVMD between these two groups (10.7 ± 6.7% vs. 12.1 ± 7.4%, p = NS). Both HF groups had significantly more dyssynchrony than controls. A scattered pattern of distribution of asynchronous segments was seen in narrow QRS patients; 33.96% of them had their earliest contracting segment, instead of delayed segment, located in areas conventionally targeted for LV pacing i.e. anterolateral, inferolateral or inferior segments.

Conclusions

3DE confirmed significant dyssynchrony in  > 50% HF patients with narrow QRS as demonstrated by other imaging methods. 3D distribution patterns of asynchronous segments indicate possibility of left ventricular mechanics related reasons responsible for lack of CRT responsiveness, an observation that generates hypothesis on possible reasons of CRT non-responsiveness.

Diastolic Dyssynchrony in Acute ST Segment Elevation Myocardial Infarction and Relationship with Functional Recovery of Left Ventricle

Background

Incidence of diastolic dyssynchrony (DD) and its impact on functional recovery of left ventricle (LV) after ST segment elevation myocardial infarction (STEMI) is not known.

Methods

Consecutive patients with STEMI who underwent successful revascularization were prospectively enrolled. Echocardiography with tissue Doppler imaging was performed within 48 hours of admission and at 6 months. LV end-diastolic volume index (EDVI), end-systolic volume index (ESVI), ejection fraction (EF), and left atrial volume index (LAVI) were calculated. Diastolic delay was calculated from onset of QRS complex to peak of E wave in tissue Doppler image and presented as maximal temporal difference between peak early diastolic velocity of 6 basal segments of LV (TeDiff). Study patients were compared with demographically matched control group.

Results

Forty eight consecutive patients (55 ± 10 years, 88% male) and 24 controls (56 ± 6 years, 88% male) were included. TeDiff was higher in STEMI than in controls (35.9 ± 19.9 ms vs. 26.3 ± 6.8 ms, p = 0.025). Presence of DD was higher in STEMI than controls (58% vs. 33%, p = 0.046) according to calculated cut-off value (≥ 29 ms). There was no correlation between TeDiff and change in EDVI, ESVI, and LAVI at 6 months, however TeDiff and change in EF at 6 months was positively correlated (r = 0.328, p = 0.023). Patients with baseline DD experienced remodeling less frequently compared to patients without baseline DD (11% vs. 38%, p = 0.040) during follow-up.

Conclusion

STEMI disrupts diastolic synchronicity of LV. However, DD during acute phase of STEMI is associated with better recovery of LV thereafter. This suggests that DD is associated with peri-infarct stunned myocardium that is salvaged with primary intervention as well as infarct size.

Early diastolic dyssynchrony in relation to left ventricular remodeling and function in hypertension

BACKGROUND

Cardiac synchronization is important in maintaining myocardial performance, but the mechanism of diastolic dyssynchrony leading to failing myocardium is unclear. We aim to study the relation of left ventricular (LV) diastolic dyssynchrony with diastolic dysfunction in patients with hypertension.

METHODS

Two-D, three-D and Doppler echocardiography were performed using the GE Vivid E9 system on 230 subjects. Among them, 154 patients with hypertension were divided into group 1 (86 patients with mild to moderate hypertension, BP 152 ± 8/91 ± 11 mm Hg) and group 2 (68 patients with severe hypertension, BP 188 ± 12/105 ± 24 mm Hg), age 76, gender matched normotensive subjects (119 ± 6/76 ± 9 mm Hg) as control. The routine 2D and Doppler parameters were measured and LV systolic and diastolic dyssynchrony indices were determined as the standard deviation of the time interval from the peak R of the QRS complex to peak myocardial systolic strain rate (Ts-SD), and to early diastolic strain rate (Te-SD) of 12 LV segments.

RESULTS

LV relative wall thickness, mass index, and Te-SD were significantly higher in patients with hypertension than in control group (p<0.0001), but Ts-SD showed no significant differences. Te-SD and diastolic dysfunction worsened progressively with increasing severity of hypertension (p<0.05). Te-SD was significantly and independently associated with parameters of LV remodeling and diastolic function.

CONCLUSION

Our study demonstrated that LV diastolic dyssynchrony was associated with LV remodeling, which seems to contribute to diastolic dysfunction in hypertension. This diastolic dyssynchrony index derived from speckle tracking echocardiography can be used as a marker for studying the LV function and effects of therapy in hypertensive heart disease.

Left ventricular systolic dyssynchrony in patients with isolated symptomatic myocardial bridge

OBJECTIVES

The impact of myocardial bridge (MB) on left ventricular (LV) systolic synchrony is insufficiently understood.

DESIGN

Thirty-five subjects with isolated mid-left, anterior, descending artery (LAD) MB, preserved LV ejection fraction (LVEF > 50%), and otherwise, normal coronary angiogram were identified from 3607 patients who underwent diagnostic coronary angiography and were evaluated by tissue Doppler imaging and real-time three-dimensional echocardiography (RT3DE). Control subjects consisted of 26 age and sex-matched coronary angiographically "normal" subjects.

RESULTS

MB patients were characterized by reduced, early, diastolic strain rate in LAD-supplied apical segments (lateral and anterior), with prevalence of LV systolic dyssynchrony of 25.7% (9/35). MB patients were further classified by the medians of MB stenosis and length. For MB stenosis < 52.5%, Class I: length < 17 mm (n = 7), Class II: length ≥ 17 mm (n = 10); for stenosis ≥ 52.5%, Class III: length < 17 mm (n = 10), Class IV: length ≥ 17 mm (n = 8). Binary Logistic regression model revealed that higher MB lesion classification (odds ratio: 4.944, 95%CI 1.174-20.82, P < 0.05) and hypertension (odds ratio: 15.32, 95%CI: 1.252-187.6, P < 0.05) are statistically associated with LV systolic dyssynchrony, which was independent of LV mass.

CONCLUSIONS

MB in the mid LAD is associated with myocardial dyssynchrony. Hypertensive individuals and those with more severe bridging (determined by length and stenosis) tend to have an increased incidence of dyssynchrony.

Ventricular dyssynchrony of idiopathic versus pacing-induced left bundle branch block and its prognostic effect in patients with preserved left ventricular systolic function

The extent of left ventricular (LV) dyssynchrony might not be comparable between right ventricular pacing-induced left bundle branch block (RV-LBBB) and idiopathic LBBB (iLBBB), despite the morphologic analogy on the electrocardiogram. The objectives of the present study were to elucidate the differences in the LV dyssynchrony index (LVdys) between RV-LBBB and iLBBB, and to assess the prognostic implication of LV dyssynchrony. The conventional echocardiographic parameters, LVdys, and LV end-systolic wall stress were evaluated in 20 healthy volunteers and 21 patients with iLBBB and 20 with RV-LBBB with preserved LV systolic function. Three types of LVdys were evaluated: LVdys-6, LVdys-2, and LVdys-standard deviation. The patients were clinically followed up for about 3 years. The prevalence of LV dyssynchrony was not rare in those with either iLBBB or RV-LBBB, but it was more prevalent in the patients with iLBBB than in those with RV-LBBB. The patients with iLBBB had greater LVdys than those with RV-LBBB (84 ± 55 vs 55 ± 50 for LVdys-6, 51 ± 49 vs 31 ± 40 for LVdys-2, 37 ± 24 vs 24 ± 22 for LVdys-standard deviation in iLBBB vs RV-LBBB). LVdys displayed significant correlations with QRS duration, LV volumes, LV ejection fraction, LV end-systolic wall stress, and mitral inflow E/mitral annular E' velocity ratio. Multivariate logistic regression analysis showed that the LV end-diastolic volume and LV end-systolic wall stress were independent determinants of the presence of LV dyssynchrony. During follow-up, no cardiovascular death or hospitalization for heart failure was reported in either group. In conclusion, despite similarities in electrocardiographic morphology, the extent of LV dyssynchrony were greater in patients with iLBBB, with LV preload and afterload the main determinants. No association was found between the presence of LV dyssynchrony and prognosis.

Effects of the aging process on left ventricular systolic and diastolic synchronicity indexes: insights from 160 "completely" healthy volunteers

BACKGROUND

Growing attempt to use left ventricular (LV) systolic (LVSIsys) and diastolic (LVSIdia) synchronicity indexes in the process of selecting potential responders to cardiac resynchronization therapy has created a need for normative reference values.

HYPOTHESIS

This study sought: (1) to determine normal reference ranges for LVSIsys and LVSIdia, and (2) to assess their relationships to age and conventional parameters reflecting LV systolic and diastolic functions.

METHODS

We recruited 160 healthy volunteers (104 men) free of any systemic or cardiovascular disease. Maximal difference and standard deviation of time to peak systolic and peak early diastolic myocardial velocities for LVSIsys and LVSIdia were measured using 6 and 12 segment models.

RESULTS

Normal ranges for LVSIsys and LVSIdia obtained in this study were slightly higher than previously reported. The normal aging process did not significantly change LVSIsys, whereas LVSIdia progressively and consistently increased with age. Significant correlations were observed between LVSIdia and parameters representing LV diastolic function, that is, early mitral inflow velocity and its deceleration time, and early mitral annulus velocity. A physiologic increase in LV mass/Ht²·⁷ showed a weak, but significant correlation with LVSIdia (r = 0.15-0.22), but not with LVSIsys. On multivariate analysis, an age-dependent increase in LVSIdia was confirmed.

CONCLUSIONS

In this study, we propose age-specific reference ranges for LVSIsys and LVSIdia. LVSIsys remains stable throughout age groups, whereas LVSIdia progressively increases with age. We believe that the reference values provided here will be useful for defining abnormal LV synchronous contraction and relaxation.

Effect of biventricular pacing on diastolic dyssynchrony

OBJECTIVES

This study sought to examine the changes in diastolic dyssynchrony with cardiac resynchronization therapy (CRT).

BACKGROUND

Little is known about the effect of CRT on diastolic dyssynchrony.

METHODS

Consecutive heart failure patients (n = 266, age 65.7 ± 10.0 years) underwent color-coded tissue Doppler imaging at baseline, 48 h, and 6 months after CRT. Systolic and diastolic dyssynchrony were defined as maximal time delay in peak systolic and early diastolic velocities, respectively, in 4 basal LV segments. CRT responders were defined as those with ≥15% decrease in LV end-systolic volume at 6 months.

RESULTS

Baseline LVEF was 25.2 ± 8.1%; 63.5% patients were CRT responders. Baseline incidence of systolic and diastolic dyssynchrony, and a combination of both was 46.2%, 51.9%, and 28.6%, respectively. Compared to nonresponders, responders had longer baseline systolic (79.2 ± 43.4 ms vs. 45.4 ± 30.4 ms; p < 0.001) and diastolic (78.5 ± 52.0 ms vs. 50.1 ± 38.2 ms; p < 0.001) delays. In follow-up, systolic delays (45.4 ± 31.6 ms at 48 h; 38.9 ± 26.2 ms at 6 months; p < 0.001) and diastolic delays (49.4 ± 36.3 ms at 48 h; 37.7 ± 26.0 ms at 6 months; p < 0.001) improved only in responders.

CONCLUSIONS

At baseline: 1) diastolic dyssynchrony was more common than systolic dyssynchrony in HF patients; 2) nonresponders had less baseline diastolic dyssynchrony compared to responders. After CRT: 1) diastolic dyssynchrony improved only in responders. Further insight into the pathophysiology of diastolic dyssynchrony and its changes with CRT may provide incremental information on patient-specific treatments.

Left ventricular systolic and diastolic dyssynchrony in coronary artery disease with preserved ejection fraction

The present study aims to evaluate LV (left ventricular) mechanical dyssynchrony in CAD (coronary artery disease) with preserved and depressed EF (ejection fraction). Echocardiography with TDI (tissue Doppler imaging) was performed in 311 consecutive CAD patients (94 had preserved EF > or =50% and 217 had depressed EF <50%) and 117 healthy subjects to determine LV systolic and diastolic dyssynchrony by measuring Ts-SD (S.D. of time to peak myocardial systolic velocity during the ejection period) and Te-SD (S.D. of time to peak myocardial early diastolic velocity during the filling period) respectively, using a six-basal/six-mid-segmental model. In CAD patients with preserved EF, both Ts-SD (32.2+/-17.3 compared with 17.7+/-8.6 ms; P<0.05) and Te-SD (26.2+/-13.6 compared with 20.3+/-8.1 ms; P<0.05) were significantly prolonged when compared with controls, although they were less prolonged than CAD patients with depressed EF (Ts-SD, 37.8+/-16.5 ms; and Te-SD, 36.0+/-23.9 ms; both P<0.005). Patients with preserved EF who had no prior MI (myocardial infarction) had Ts-SD (32.9+/-17.5 ms) and Te-SD (28.6+/-14.8 ms) prolonged to a similar extent (P=not significant) to those with prior MI (Ts-SD, 28.4+/-16.8 ms; and Te-SD, 25.5+/-15.0 ms). Patients with class III/IV angina or multi-vessel disease were associated with more severe mechanical dyssynchrony (P<0.05). Furthermore, the majority of patients with mechanical dyssynchrony had narrow QRS complexes in those with preserved EF. This is in contrast with patients with depressed EF in whom systolic and diastolic dyssynchrony were more commonly associated with wide QRS complexes. In conclusion, LV mechanical dyssynchrony is evident in CAD patients with preserved EF, although it was less prevalent than those with depressed EF. In addition, mechanical dyssynchrony occurred in CAD patients without prior MI and narrow QRS complexes.

Left ventricular systolic and diastolic dyssynchrony in asymptomatic hypertensive patients

BACKGROUND

Diastolic and systolic dyssynchrony are common in patients with heart failure. However, the presence of dyssynchrony in asymptomatic patients with hypertension who are susceptible to the development of heart failure is not well understood. The aims of this study were (1) to evaluate the prevalence of systolic and diastolic dyssynchrony and (2) to identify the main determinants of left ventricular (LV) dyssynchrony in asymptomatic patients with hypertension.

METHODS

One hundred ten patients with hypertension consecutively enrolled were compared with 55 age-matched and gender-matched normal control subjects. Comprehensive echocardiography was performed, including conventional and Doppler tissue imaging parameters. LV end-systolic wall stress was calculated using a hemodynamic and echocardiographic M-mode data set. For the assessment of LV dyssynchrony, both the standard deviation of the time from QRS onset to peak systolic velocity and the maximal difference of the time from QRS onset to peak systolic velocity from 6 basal segments at the apical views were used and were compared between the two groups.

RESULTS

Both systolic and diastolic dyssynchrony indexes were significantly higher in patients with hypertension than in the normal controls (P < .001), with no significant correlation between the systolic and diastolic dyssynchrony indexes. The proportions of patients with hypertension who had LV systolic and diastolic dyssynchrony were 24% and 21%, respectively. Multivariate analysis showed that the E/E' ratio (P < .001) was independently associated with LV systolic dyssynchrony, whereas LV mass index (P = .001) and E/E' (P < .001) were major determinants of LV diastolic dyssynchrony.

CONCLUSIONS

LV systolic and diastolic dyssynchrony are not uncommon in asymptomatic patients with hypertension and are significantly associated with LV filling pressure. The determinants of LV systolic dyssynchrony are not the same as those of diastolic dyssynchrony, implying that different mechanisms are involved in the development of LV systolic and diastolic dyssynchrony in asymptomatic patients with hypertension.

Long-term prognostic value of an index of myocardial performance in patients with myocardial infarction

BACKGROUND

The Tei index of myocardial performance (IMP), which combines parameters of both systolic and diastolic ventricular function, is a useful prognostic factor in many clinical settings.

HYPOTHESIS

This study assessed the long-term prognostic value of IMP in patients discharged from hospital after acute myocardial infarction (AMI).

METHODS

Doppler/echocardiographic studies were recorded in 90 consecutive patients on Day 14 +/- 2 following an AMI. The IMP was calculated from the Doppler recordings, as a sum of isovolumetric contraction time and isovolumetric relaxation time, divided by the ejection time.

RESULTS

The patients were followed for an average (SD) of 57.8 (16.1) months. During this period there were 22 (24%) cardiac events, defined as cardiac deaths (10) or nonfatal recurrent myocardial infarctions (12). After multivariate Cox analysis, Tei index > 0.55 (relative risk [RR] 4.45; 95% confidence interval [CI] 1.28-15.45; p = 0.019), LV end-systolic volume > 65 ml (RR 3.23; 95% CI 1.34-7.79; p = 0.009), and mitral E wave deceleration time < or = 0.145 s (RR 2.94; 95% CI 1.24-6.92; p = 0.014) were the only independent predictors of cardiac events during the follow-up period. In a subgroup of patients with preserved LV systolic function (ejection fraction > 0.40), IMP was the only predictor of cardiac events (RR 6.37; 95% CI 1.32-30.77, p = 0.02).

CONCLUSIONS

The Tei index of myocardial performance, which is simple and easy to calculate, is a useful tool for risk assessment in patients following myocardial infarction, and in a subgroup of patients with normal or only mildly impaired systolic function.

The effects of ventricular asynchrony on myocardial perfusion

Asynchronous depolarization and contraction sequence, secondary to intraventricular conduction defects or to permanent right ventricular apical pacing, is associated with adverse effects that may be clinically evident in the failing heart. Experimental and clinical studies have suggested that asynchronous ventricular contraction deteriorates left ventricular performance and induces unfavourable left ventricular remodelling. Although such contraction does not appear to affect resting coronary artery blood flow, it increases endomyocardial pressure during diastole and decreases regional myocardial perfusion in the interventricular septum. The magnitude of these effects may correlate with the duration of the asynchrony. Despite these detrimental effects, there is no evidence that ventricular asynchrony reduces collateral myocardial blood flow, myocardial oxygen consumption or cardiac efficiency, neither in patients with normal coronary arteries, nor in patients with coronary artery disease. Furthermore, in patients with acute ischaemic syndromes, ventricular asynchrony exerts a neutral effect on the ischaemic myocardium. Cardiac resynchronization therapy improves left ventricular systolic and diastolic function without an increase in myocardial oxygen consumption or energy cost. This therapy may decrease the inhomogeneity in regional oxidative metabolism, myocardial perfusion and cardiac efficiency. Further experimental and clinical studies are needed on this area.

Long-term effects of antilipidaemic therapy on left ventricular function in patients with dyslipidaemia: multigated radionuclide ventriculography study

AIM

It has been reported that dyslipidaemia impairs left ventricular systolic (LVs) and diastolic (LVd) functions, irrespective of atherogenic effects, in the setting of coronary artery disease. The aim of the present study was to evaluate the effects of anti-lipidaemic therapy on LVs and LVd functions by means of multigated radionuclide ventriculography (RNV) in subjects with signs of dyslipidaemia and with preserved left ventricular function.

METHODS

Eighteen patients with dyslipidaemia (eight men, 10 women, mean age 50+/-10 years) were included in the study. While the clinical examination and treadmill exercise test results were normal in all patients, low-density lipoprotein levels exceeded 160 mg . dl. Patients with medical conditions including coronary artery disease, hypertension, diabetes, cardiomyopathy and valvular heart disease which would influence left ventricular function were excluded from the study. RNV was performed in all subjects, taking into account the best septal position to differentiate the left ventricle from the right ventricle. The following parameters were calculated: ejection fraction, peak ejection rate (PER), time to peak ejection (TPER), a ejection rate (aER), a ejection fraction (aEF), Peak filling rate (PFR), time to peak filling rate (TPFR), a filling rate (aFR), a filling fraction (aFF).

RESULTS

The low-density lipoprotein value decreased and the high-density lipoprotein value increased after statin therapy (P<0.001 and P<0.003, respectively). PER, aER and aFF significantly increased and TPER decreased as a consequence of statin therapy (respectively, P<0.05, P<0.05, P<0.05 P<0.05).

CONCLUSION

Anti-lipidaemic therapy is effective in dyslipidaemic patients. RNV is a useful and non-invasive method for monitoring changes in ventricular function following anti-lipidaemic treatment strategies.

Time to peak velocity measurements by pulsed wave Doppler tissue imaging to quantify ischemia-related regional myocardial asynchrony

A total of 173 patients with chest pain but without visually discernible wall-motion abnormalities by 2-dimensional echocardiography underwent pulsed wave Doppler tissue imaging examination before angiography. Segmental longest time to peak contraction velocity (Tpv) was acquired through 3 apical views. The longest time period from electrocardiographic R wave to peak velocity on segmental velocity integrals of nonapical segments was measured. Receiver operating characteristic curve analysis was performed for correlation analysis between segmental Tpv and significant (>or=50% luminal diameter stenosis) coronary artery stenosis. Analysis of variance test was used to compare among different patient groups with 0, 1, 2, and 3 coronary artery stenoses. Delay in Tpv on any 1 or more of the 12 nonapical segments was noted in 72 of 116 patients with angiographically significant coronary stenosis. When the longest segmental Tpv of >or=340 milliseconds was selected as a cut-off value for identification of a significant left circumflex or multivessel coronary artery stenosis, the area under receiver operating characteristic curve was 0.69 and 0.72, respectively (P =.000 and.0013, respectively). In conclusion, pulsed wave Doppler tissue imaging technique provides objective quantitative information for identification of multivessel or left circumflex coronary artery stenosis in patients with chest pain but without apparent wall-motion abnormalities on echocardiography.

Regional left ventricle mechanical asynchrony in patients with heart disease and normal QRS duration: implication for biventricular pacing therapy

LV electromechanical delay results in asynchronized contraction. However, it is not known if the presence of cardiac diseases without QRS prolongation may result in inter- or intraventricular asynchrony. This study investigated the occurrence of systolic mechanical delay in different regions of the LV in patients with underlying heart diseases and normal QRS duration. Tissue Doppler imaging (TDI) was performed in 141 patients (age 63.7 +/- 11.5 years) with underlying heart diseases (82% had ischemic heart disease) and 92 normal healthy volunteers (age 63.9 +/- 9.8 years) based on the four-basal and four-mid-segment model by apical views. Of these, 124 patients had normal QRS duration (< or = 120 ms) while 17 were prolonged due to LBBB or intraventricular conduction defect. Patients with normal QRS duration had significantly lower peak myocardial isovolumic contraction velocity (IVCM), sustained systolic velocity (SM), and prolonged time to peak IVCM and SM in almost all myocardial segments when compared to controls. The time to peak IVCM (basal lateral vs basal septal segment: 61.0 +/- 29.4 vs 53.3 +/- 24.1 ms, P < 0.005) and SM (basal lateral vs basal septal segment: 174 +/- 44 vs 154 +/- 36 ms, P < 0.001) was further delayed in the LV free-wall segments. Mechanical delay was also evident in the LV free-wall segments in patients with preserved or impaired systolic function, in patients with or without previous myocardial infarction, and in patients with prolonged QRS duration. Patients with prolonged QRS had a higher prevalence of LV free-wall delay of > 50 ms (47 vs 24%, chi-square = 4.6, P < 0.05). In conclusion, the presence of cardiac diseases was characterized by LV global mechanical delay; and, intraventricular asynchronized contraction characterized mostly by further mechanical delay in the free-wall region. These changes occur even in those with normal QRS duration.

High prevalence of left ventricular systolic and diastolic asynchrony in patients with congestive heart failure and normal QRS duration

OBJECTIVE

To study the possible occurrence of left ventricular (LV) systolic and diastolic asynchrony in patients with systolic heart failure (HF) and narrow QRS complexes.

DESIGN

Prospective study.

SETTING

University teaching hospital.

PATIENTS

200 subjects were studied by echocardiography. 67 patients had HF and narrow QRS complexes (< or = 120 ms), 45 patients had HF and wide QRS complexes (> 120 ms), and 88 served as normal controls.

INTERVENTIONS

Echocardiography with tissue Doppler imaging was performed using a six basal, six mid-segmental model.

MAIN OUTCOME MEASURES

Severity and prevalence of systolic and diastolic asynchrony, as assessed by the maximal difference in time to peak myocardial systolic contraction (T(S)) and early diastolic relaxation (T(E)), and the standard deviation of T(S) (T(S)-SD) and of T(E) (T(E)-SD) of the 12 LV segments.

RESULTS

The mean (SD) maximal difference in T(S) (controls 53 (23) ms v narrow QRS 107 (54) ms v wide QRS 130 (51) ms, both p < 0.001 v controls) and in T(S)-SD (controls 17.0 (7.8) ms v narrow QRS 33.8 (16.9) ms v wide QRS 42.0 (16.5) ms, both p < 0.001 v controls) was prolonged in the narrow QRS group compared with normal controls. Similarly, the maximal difference in T(E) (controls 59 (19) ms v narrow QRS 104 (71) ms v wide QRS 148 (87) ms, both p < 0.001 v controls) and in T(E)-SD (controls 18.5 (5.8) ms v narrow QRS 33.3 (27.7) ms v wide QRS 48.6 (30.2) ms, both p < 0.001 v controls) was prolonged in the narrow QRS group. The prevalence of systolic and diastolic asynchrony was 51% and 46%, respectively, in the narrow QRS group, and 73% and 69%, respectively, in the wide QRS group. Stepwise multiple regression analysis showed that a low mean myocardial systolic velocity from the six basal LV segments and a large LV end systolic diameter were independent predictors of systolic asynchrony, while a low mean myocardial early diastolic velocity and QRS complex duration were independent predictors of diastolic asynchrony.

CONCLUSIONS

LV systolic and diastolic mechanical asynchrony is common in patients with HF with narrow QRS complexes. As QRS complex duration is not a determinant of systolic asynchrony, it implies that assessment of intraventricular synchronicity is probably more important than QRS duration in considering cardiac resynchronisation treatment.

Abnormal global left ventricular relaxation occurs early during the development of pharmacologically induced ischemia

In animal and human models, left ventricular (LV) diastolic function has been observed to be highly sensitive to myocardial ischemia. The response of LV diastolic parameters to pharmacologically induced ischemia, however, has not been characterized and might be important in the interpretation of dobutamine stress echocardiography. Eight mongrel dogs, in which were inserted a high-fidelity micromanometer LV catheter, coronary sinus sampling catheter, and ultrasonic coronary artery flow probe, underwent intravenous dobutamine infusion at escalating doses both before (control protocol) and after (ischemia protocol) creation of left anterior descending coronary artery stenosis with a hydraulic cuff occluder adjusted to maintain resting coronary artery flow but attenuate reactive hyperemia. At each dobutamine dose, epicardial short-axis 2-dimensional echocardiographic images and hemodynamic measurements were obtained. LV diastolic function was examined by calculation of peak (-)dP/dt and the time constant of isovolumic relaxation (tau). The dobutamine infusion protocol was terminated on the earliest recognition of an anterior wall motion abnormality. Peak (+)dP/dt normalized for developed isovolumetric pressure was calculated as a relatively load-independent index of global LV contractile function. Dobutamine infusion with and without ischemia resulted in comparable changes in heart rate and (+)dP/dt/IP, with no change in LV end-diastolic or -systolic pressure. The magnitude of peak (-)dP/dt increased less during the ischemia (1231 +/- 109 to 1791 +/- 200 mm Hg/sec) versus the control (1390 +/- 154 to 2432 +/- 320 mm Hg/sec) protocol (P <.05). Similarly, the observed decrease in tau was less during the ischemia (53 +/- 3 to 38 +/- 4 msec) than the control (51 +/- 5 to 23 +/- 3 msec) protocol, corresponding to a slower rate of relaxation (P <.05). In addition, the smaller decrease in tau was observed at the dobutamine dose before the dose at which an echocardiographic wall motion abnormality was first recognized. Dobutamine-induced ischemia is associated with abnormal LV diastolic function. In addition, these abnormalities seem to occur early in the development of ischemia. These observations extend to pharmacologically induced ischemia prior findings from other models of ischemia, suggesting the high sensitivity of LV diastolic function to the development of myocardial ischemia.

Amplitudes, durations, and timings of apically directed left ventricular myocardial velocities: II. Systolic and diastolic asynchrony in patients with left ventricular hypertrophy

BACKGROUND

Regional myocardial dysfunction may be the earliest manifestation of myocardial disease and can occur in the absence of abnormalities of global left ventricular (LV) function. The LV long-axis function, which is mainly due to subendocardial muscle fibers, may become abnormal in the presence of normal short-axis function. This study investigates the temporal and spatial characteristics of the LV long-axis function in patients with secondary LV hypertrophy in the presence of normal systolic function.

METHODS AND RESULTS

LV long-axis myocardial velocities were recorded in 18 patients with LV hypertrophy and preserved regional and global systolic function with Doppler tissue imaging. Apically directed myocardial velocities were recorded from the basal, mid, and apical segments of the four LV walls, and their amplitudes, timings, and durations were measured. The abnormalities uncovered by the analysis of regional myocardial velocities included (1) asynchrony in the onset of myocardial contraction circumferentially, (2) presence of postejection LV shortening, (3) asynchrony in the onset of early myocardial lengthening circumferentially, (4) reduced early myocardial lengthening velocity, (5) reduced early to late myocardial lengthening velocity and extents circumferentially, and (6) lack of variation in the basal myocardial velocities circumferentially in contrast to normal individuals.

CONCLUSIONS

Patients with secondary LV hypertrophy with preserved regional and global systolic performance have distinct abnormalities in the timings and amplitudes of apically directed myocardial velocities. These abnormalities may explain some of the changes in LV global diastolic behavior and may also serve as markers of early regional myocardial dysfunction.

Functional myocardial perfusion abnormality induced by left ventricular asynchronous contraction: experimental study using myocardial contrast echocardiography

OBJECTIVES

The aim of this study was to clarify how myocardial perfusion is impaired by asynchronous contraction.

BACKGROUND

False septal hypoperfusion is noted in some patients with left bundle branch block.

METHODS

Eight dogs were examined with epicardial pacing at the left ventricular posterior wall, the right ventricular anterior wall and, as a control, the right atrial appendage. The pacing rate was 80, 110 and 150 beats/min (bpm). Myocardial perfusion was assessed by contrast echocardiography.

RESULTS

Left ventricular pacing at 80 and 110 bpm did not change systolic wall thickening or contrast intensity at the pacing site, although an early excitation notch was noted at the pacing site. However, at 150 bpm, systolic thickening was impaired (23.3 +/- 4.2% vs. 37.0 +/- 2.6% during atrial pacing, p < 0.05), and the peak intensity ratio of the pacing site to the ventricular septum was significantly decreased (24.1 +/- 5.7% vs. 37.0 +/- 2.8% at a pacing rate of 80 bpm, p < 0.01). The peak intensity ratio correlated with systolic wall thickening at the pacing site (y = 0.413 x -0.028, r = 0.81, p < 0.0001). However, right ventricular pacing did not change either systolic thickening or the peak intensity ratio at any pacing rate, although an early excitation notch was noted on the ventricular septum.

CONCLUSIONS

Wall motion abnormalities after early excitation vary depending on the pacing mode. When tachycardia induces regional wall motion abnormalities, the ventricular wall of the pacing site is functionally hypoperfused.

Alteration of left ventricular diastolic function during coronary angioplasty-induced ischemia: a color M-mode Doppler study

OBJECTIVES

The aim of this study was to assess the effects of ischemia on diastolic function by analyzing flow propagation velocity with color M-mode Doppler echocardigraphy.

BACKGROUND

Color M-mode Doppler echocardiography has been proposed as a method of assessing left ventricular filling.

METHODS

Color M-mode Doppler echocardiography and measurement of hemodynamic data were performed simultaneously at baseline and during angioplasty-induced ischemia. Tau was compared with flow propagation velocity. Late diastolic indexes, left ventricular pressure and flow cessation time were also investigated.

RESULTS

During ischemia, left ventricular relaxation rate (tau) increased, whereas flow propagation velocity decreased, from (mean +/- SD) 46.8 +/- 10 ms to 72.6 +/- 18.3 ms and from 59.8 +/- 15.8 cm/s to 30 +/- 8 cm/s, respectively (all p < 0.0001). The maximal slowing of flow propagation velocity was observed 20 to 30 s after the beginning of the inflation, coexisting with a notch on the ascending limb of the negative rate of rise of the left ventricular pressure (dP/dt) curve. Flow propagation velocity was correlated with tau both at baseline (r = 0.53, p < 0.05) and during inflation (r = 0.53, p < 0.03). Left ventricular end-diastolic pressure increased during ischemia from 13.5 +/- 8 mm Hg at baseline to 27.5 +/- 7 mm Hg, while a premature cessation of the entering flow occurred -13.8 +/- 23 ms before the next Q wave onset, compared with 4.5 +/- 19.6 ms after the Q wave onset at baseline (all p < 0.0001).

CONCLUSIONS

The analysis of flow propagation velocity showed that early filling is highly dependent on left ventricular relaxation rate, particularly through the phenomenon of asynchrony. During ischemia, the premature cessation of late filling is associated with increased diastolic pressures.

Prolonged impairment of regional contractile function after resolution of exercise-induced angina. Evidence of myocardial stunning in patients with coronary artery disease

BACKGROUND

Delayed recovery of contractile function in spite of normal perfusion (ie, "stunning") has been described in animal models of exercise-induced myocardial ischemia. Therefore, we investigated whether stunning may result from effort angina in patients.

METHODS AND RESULTS

Patients with coronary artery disease underwent exercise testing combined with quantitative measurements of contractile function for up to 240 minutes after exercise determined by either measurement of regional ejection fraction (99mTc radionuclide angiography; n = 17, group A) or computer-assisted measurement of systolic wall thickening (n = 14, group B). In the latter group, myocardial perfusion was also evaluated by 99mTc-sestamibi tomographic imaging. Angina induced marked contractile dysfunction. Hemodynamic and ECG changes brought about by ischemia were promptly normalized. Furthermore, no perfusion defects could be detected in group B patients 30 minutes after exercise, yet contractile function remained impaired well after cessation of exercise. Thirty minutes into recovery, regional ejection fraction of previously ischemic areas was still 82.6 +/- 4.6% of baseline in group A (P < .05). Similarly, in group B patients, systolic thickening of previously ischemic segments was still significantly impaired 60 minutes after exercise, averaging 33.8 +/- 2.8% versus 40.5 +/- 2.7% at baseline (P < .05). Contractile impairment was fully reversible, as the functioning of previously ischemic segments normalized between 60 and 120 minutes of recovery.

CONCLUSIONS

Prolonged yet ultimately reversible impairment of regional myocardial function may occur in patients after exercise-induced angina in the absence of perfusion abnormalities. These findings indicate that myocardial stunning may ensue after effort angina in patients with severe coronary artery disease.

Normalization of left ventricular nonuniformity late after valve replacement for aortic stenosis

The aim of the present study was to evaluate nonuniformity in pressure overload hypertrophy due to aortic stenosis. Twenty patients were included in the present analysis. Ten patients with severe aortic stenosis were studied preoperatively as well as early (21 +/- 8 months) and (89 +/- 21 months) after aortic valve replacement (AVR) using left ventricular biplane angiograms, high-fidelity pressure measurements and endomyocardial biopsies. Ten normal subjects served as controls. LV systolic function was assessed from biplane ejection fraction, and diastolic function from the time constant of relaxation, the peak filling rate and the constant of myocardial stiffness. Nonuniformity was evaluated from the coefficient of variation of the time to end-systole (systolic asynchrony) and peak filling rate (diastolic asynchrony) of 12 regions in right anterior oblique and left anterior oblique projection. Ejection fraction was comparable in patients with aortic stenosis and in controls, whereas preoperatively diastolic dysfunction with prolonged relaxation and increased stiffness was present in patients with aortic stenosis and was normalized late after AVR. LV systolic asynchrony was present (>25D of controls) in 7 and diastolic asynchrony in 10 of 10 patients with aortic stenosis. Early as well as late after AVR systolic asynchrony was normalized in 9 of 10 patients. Diastolic asynchrony was present early AVR in all but one patient, although there was a significant improvement with respect to the preoperative evaluation. Late after AVR there was a normalization of diastolic asynchrony in 9 of 10 patients with aortic stenosis. Thus, it is concluded that systolic asynchrony is normalized early after AVR probably due to its load-sensitivity, whereas diastolic asynchrony persists probably due to residual LV hypertrophy with increased interstitial fibrosis and myocardial stiffness. Late after AVR, diastolic asynchrony is normalized due to structural remodeling with regression of both myocardial hypertrophy and interstitial fibrosis.

Noninvasive estimation of pulmonary arterial wedge pressure with Doppler transmitral flow velocity pattern in patients with known heart disease

Pulmonary arterial wedge pressure (PAWP) is an important marker of cardiac function. Regrettably, it requires catheterization, which can occasionally result in serious complications. A noninvasive method of estimating PAWP would thus be helpful. Recent studies have indicated that the Doppler transmitral flow velocity pattern was strongly dependent on preload and could provide an estimate of PAWP. This study was therefore designed to evaluate the relation between doppler transmitral flow velocity indexes and measured PAWP in 91 patients (learning group: 73 men, mean age 57 +/- 13 years) with ischemic heart disease (n = 41), dilated (n = 29) or hypertrophic cardiomyopathy (n = 4), or aortic stenosis (n = 17). Multiple regression analysis was used to derive an equation for estimation of PAWP, which was subsequently tested in a separate group of 33 patients (testing group: 28 men, mean age 58 +/- 12 years) with similar cardiac conditions. PAWP ranged from 4 to 48 mm Hg in the learning group and from 7 to 40 mm Hg in the testing group. In the learning group, PAWP correlated with the E/A ratio (r = 0.95), atrial filling fraction (r = -0.80), peak E velocity (r = 0.79), isovolumic relaxation period (r = -0.75), and deceleration time (r = -0.61). In the learning group, PAWP was best predicted as PAWP = 18.4 + [17.1.In(E/A ratio)]. This equation allowed prediction of PAWP within 3 mm Hg of the measured value in 24 of 33 patients (73%) in the testing group. In 8 additional patients, the equation also accurately predicted the changes in PAWP induced by volume loading or intravenous nitrates (r = 0.98).(ABSTRACT TRUNCATED AT 250 WORDS)

Coronary collateral circulation and diastolic function

Patients with coronary artery disease reportedly have an impaired left ventricular filling. To evaluate the effects of coronary collaterals on diastolic function in patients with effort-induced angina, resting radionuclide ventriculography was performed in 14 patients with severe isolated (> or = 90% diameter) stenosis of the left anterior descending coronary artery and in seven normal subjects. Contrast ventriculography showed normal wall motion in all patients. Functional indices obtained by radionuclide ventriculography were compared between those patients with collateral vessels, Rentrop classification grades 1 (n = 7) and 3 (n = 1), and those patients without (n = 6) collateral vessels. Global peak filling rate was significantly (P < 0.01) reduced in the patients with collaterals. The septal, apical and lateral peak filling rates were also reduced in patients with collateral vessels, with the reduction in lateral peak filling rate being statistically significant (P < 0.05). The indices of systolic function and the temporal diastolic asynchronous index were similar, irrespective of the presence of collaterals. The exercise tolerance as evaluated by the rate-pressure product at peak treadmill exercise stress testing in 12 patients was significantly (P < 0.01) lower in those with collateral vessels. Angiographically visible collaterals could be a marker for more severe coronary stenosis in patients with effort-induced angina, and an indicator of the severity of deterioration in left ventricular diastolic function.

Effects of induced asynchrony on left ventricular diastolic function in patients with coronary artery disease

OBJECTIVES

This study was designed to increase asynchrony with sequential atrioventricular (AV) pacing and to study its effects on left ventricular isovolumetric relaxation, rapid filling and stiffness.

BACKGROUND

Left ventricular nonuniformity is a major determinant of diastolic function.

METHODS

Thirteen patients with coronary artery disease were studied by simultaneous equilibrium radionuclide angiography and cardiac catheterization during atrial and AV pacing. Ejection fraction and peak filling rate were measured by radionuclide angiography. Regional analysis was obtained by analyzing time-activity curves of four left ventricular sectors; systolic and diastolic asynchrony were evaluated as the coefficient of variation of time to end-systole and, respectively, time to peak filling rate in the four sectors. Cardiac index and left ventricular pressure were measured with high fidelity catheters at cardiac catheterization. The time constant of isovolumetric relaxation was derived from left ventricular pressure. Pressure-volume loops were assembled and constants of chamber stiffness were computed.

RESULTS

Atrioventricular pacing led to a decrease in cardiac index (3.7 +/- 0.9 to 3.3 +/- 0.8 liters/min per m2, p = 0.01) and peak filling rate (352 +/- 125 to 287 +/- 141 ml/s, p = 0.03; 2.4 +/- 0.8 to 2.0 +/- 0.8 end-diastolic counts/s, p = 0.02; 4 +/- 1.3 to 3.2 +/- 1.0 stroke counts/s, p = 0.008). The time constant of isovolumetric relaxation increased (57 +/- 10 to 64 +/- 12 ms, p = 0.04) and the global diastolic pressure-volume relation shifted upward.

CONCLUSIONS

Atrioventricular pacing induces left ventricular asynchrony, which is associated with a slower rate of isovolumetric relaxation. The isovolumetric relaxation lasts after the filling phase has begun, thereby reducing the rate of rapid filling.