Reiko Mizuno

Estimation of the right ventricular volume and ejection fraction by transthoracic three-dimensional echocardiography

Aims. To validate the use of three-dimensional transthoracic echocardiography compared with the magnetic resonance imaging for determination of right ventricular volume and ejection fraction. Methods and results: We recorded transthoracic echocardiographic images starting from the apical four-chamber view in which the RV is clearly visualized in 15 healthy volunteers. The scanning plane of the RV was obtained by the rotational scanning technique in 2 degree angular increments for three-dimensional reconstruction. The RV volumes in end-diastole and end-systole were calculated using a Tomtec three-dimensional reconstruction computer. We also assessed the RV by cine magnetic resonance imaging using the Siemens Magnetom Impact Expert (1.0 T). Cine gradient echo images were obtained in the short axis of the RV. The RV volume at each phase was calculated by Simpsons method. We also calculated the RV ejection fraction. The RV volumes in end-diastole and end-systole were 111±22 ml and 52±13 ml, respectively as determined by three-dimensional echo, and 115±18 ml and 55±14 ml determined by MRI. The right ventricular volumes at end-diastole and end-systole determined by three-dimensional echo were correlated with the volumes determined by MRI (r=0.94 and 0.97, respectively, p<0.001). The RV ejection fraction determined by three dimensional echo was also correlated with the ejection fraction determined by MRI (r=0.90, p<0.01). Conclusions. Three-dimensional transthoracic echocardiography provided reliable calculations of the right ventricular volume and ejection fraction.

Clinical application of wave intensity for the treatment of essential hypertension

Wave intensity analysis is a method of studying intravascular flow wave propagation, calculated as the product of the rate of change in pressure (dP/t) and the rate of change in velocity (dU/dt). The typical pattern of wave intensity seen during the cardiac cycle has two dominant peaks. The larger first peak (FP) occurs during early systole when a forward traveling compression wave is generated by the left ventricle. The second smaller peak (SP) follows a period of relatively little net wave production during mid-systole. Wave reflection is seen as a small backward-traveling compression wave occurring just after the first peak of wave intensity (NP). In this study, we investigated the usefulness of parameters from the wave intensity for estimating the efficacy of the Α-1 blocker, doxazosin, to reduce blood pressure, by the reduction of peripheral vascular resistance. We examined 20 patients with essential hypertension. Patients were included if their diastolic blood pressure was ≫95 mmHg on at least three separate visits to the clinic. The study consisted of a 2-week baseline phase followed by a 2–4-week dose-adjusted phase with doxazosin. Treatment began with 1 mg/day doxazosin, and the dose was doubled fortnightly until the diastolic blood pressure was ≪90 mmHg. Blood–pressure measurements and side effects were recorded at intervals of 2 weeks. Before and after 4 weeks of stable treatment with doxazosin, a comprehensive clinical evaluation was given. Doxazosin reduced systolic and diastolic blood pressure. Both FP and SP increased and NP decreased. ΔMBP (change in mean blood pressure) correlated well with NP before and after the antihypertensive therapy. The efficacy of doxazosin was confirmed by the decreased reflection wave of aortic flow from wave intensity analysis. Thus, patients with a significant reflection wave may be good candidates for antihypertensive treatment by a vasodilator, such as doxazosin.

Ultrasonic tissue characterization in patients with dilated cardiomyopathy: comparison with findings from right ventricular endomyocardial biopsy

Aim: The clinical usefulness of integrated backscatter (IB) imaging was compared with right ventricular endomyocardial biopsy for assessing myocardial damage in patients with dilated cardiomyopathy (DCM). Methods: We examined 15 patients with DCM and 20 healthy controls. In addition to the conventional M-mode echocardiographic parameters, we determined the cyclic variation in IB values (CV-IB) obtained from parasternal short axis views of the left ventricle just under the transducer for both the interventricular septum (IVS) and the left ventricular posterior wall (PW). The per cent fibrosis area (%) and the transverse diameter of myocytes (μm) were measured in right ventricular endomyocardial biopsy specimens by computer image analysis. To analyze the relationship between pathological findings and CV-IB, we divided patients into four subgroups on the basis of the pathological characteristics of endomyocardial biopsy specimens as follows: degeneration dominant group (n = 5), fibrosis dominant group (n = 5), dilated phase hypertrophic cardiomyopathy (n = 2), and mixed type (n = 3). Results: CV-IB in the IVS and the PW was lower in patients with DCM (8.8 ± 2.9, 8.3 ± 2.7 dB, respectively) than in normal subjects (14.4 ± 2.9, 13.6 ± 2.6 dB, respectively). Biopsy findings showed a mean per cent fibrosis area of 24.0 ± 12.3%, and a mean myocyte diameter of 14.3 ± 2.9 μm in patients with DCM. CV-IB was correlated with both of these findings: per cent fibrosis area (r = −0.56 in IVS, r = −0.56 in PW) and myocyte diameter (r = 0.67 in IVS, r = 0.71 in PW). CV-IB was decreased in all DCM subgroups compared with normal subjects, but there was no significant difference between subgroups. Conclusions: CV-IB was correlated with both the extent of fibrosis in myocardial tissue and the myocyte diameter. These findings suggest that ultrasonic tissue characterization is a good indicator of the severity of fibrosis and myocyte atrophy in patients with DCM.

Does the progression of myocardial fibrosis lead to atrial fibrillation in patients with hypertrophic cardiomyopathy

The majority of left ventricular (LV) inflow volumes in hypertrophic cardiomyopathy (HCM) depend on atrial contraction because of impaired LV relaxation. If HCM is complicated by atrial fibrillation (AF), heart failure can develop because of the loss of atrial contraction. The purpose of this study was to determine the relationship between the development of AF and myocardial fibrosis or intramyocardial small artery (IMSA) stenosis in autopsied hearts with HCM. Studies were performed in five HCM hearts with AF (AF group) and five HCM hearts without AF (non-AF group). LV specimens were divided into the inner (IT), middle (MT), and outer (OT) thirds. We selected at random 120 fields and 20 IMSAs from each layer and assessed them quantitatively using an image analyzer. We determined the extent of fibrosis (%F) and the degree of stenosis of each IMSA (%L). The %F in the AF group was greater than in the non-AF group (P<.01). In the AF group, the %F of the IT was greater than in the MT and the OT (P<.01). In the non-AF group, the %F of the IT was greater than in the MT (P<.05), and the %F of the MT was greater than in the OT (P<.01). The %L was similar in the AF and non-AF groups. In both groups, the %L of the IT was lower than in the MT (P<.01), which was lower than that of the OT (P<.05). LV fibrosis is more severe in patients with HCM and AF than in those without AF. Therefore, myocardial fibrosis might impair LV relaxation, resulting in hemodynamic intolerance to AF.

Cardiac Raynaud's phenomenon induced by cold provocation as a predictor of long-term left ventricular dysfunction and remodelling in systemic sclerosis: 7-year follow-up study

The clinical importance of cold‐induced reversible myocardial ischaemia, known as cardiac Raynauds phenomenon (C‐Raynaud), has not been established in systemic sclerosis (SSc). This prospective study investigated the impact of C‐Raynaud on long‐term irreversible left ventricular (LV) functional and morphologic deterioration in SSc.

Non-Invasive Quantitation of Myocardial Fibrosis Using Combined Tissue Harmonic Imaging and Integrated Backscatter Analysis in Dilated Cardiomyopathy

Background: Echocardiographic modalities have challenged the myocardial tissue characterization, but this reliability has not reached to the clinical use. This study investigated whether combined tissue harmonic imaging (THI) and integrated backscatter analysis (IB) provide the reliable and quantitative information about myocardial fibrosis in idiopathic dilated cardiomyopathy (DCM) in comparison with myocardial biopsy findings. Methods: We studied 56 patients with DCM. All patients underwent left ventricular endomyocardial biopsy and IB with fundamental imaging (FI) and THI. Results: In patients with good echocardiographic image quality, excellent correlations between the percentage of area occupied by myocardial fibrosis (% fibrosis) and the mean of integrated backscatter during a cardiac cycle (m-IB) measured with FI or THI were seen, and the correlation was closer with THI compared with FI. While in patients with poor image quality the correlation between m-IB and % fibrosis was only modest with FI, but the correlation was excellent with THI. Four cut-off values of m-IB with THI obtained from receiver operating characteristic curve discriminated between % fibrosis of more and less than 25, 30, 35, and 40% with high sensitivity and specificity. Multivariate analysis revealed that m-IB with THI was an independent predictor for discrimination of the severity of myocardial fibrosis. Conclusion: Combined IB and THI are a clinically applicable method and may be an alternative to myocardial biopsy in evaluating quantitatively myocardial fibrosis in DCM.

Myocardial Ultrasonic Tissue Characterization for Estimating Histological Abnormalities in Hypertrophic Cardiomyopathy: Comparison with Endomyocardial Biopsy Findings

Aims: In this study, we investigated the clinical usefulness of ultrasonic tissue characterization with integrated backscatter for the evaluation of myocardial histological abnormalities in comparison with endomyocardial biopsy findings in patients with hypertrophic cardiomyopathy. Methods: Twenty patients with hypertrophic cardiomyopathy and 20 normal subjects were enrolled in this study. We measured two parameters for the ultrasonic tissue characterization with integrated backscatter: the magnitude of the cardiac-cycle-dependent variation in integrated backscatter signals (cdv-IB) and the mean value of integrated backscatter signals calibrated by the pericardium (cal-IB). These parameters were measured at both the interventricular septum and the left ventricular posterior wall. Histological findings of right ventricular endomyocardial biopsy specimens were analyzed by computer image analyzer. Results: cdv-IB was significantly lower and cal-IB significantly higher in both the interventricular septum and the left ventricular posterior wall in patients with hypertrophic cardiomyopathy compared with normal subjects. In patients with hypertrophic cardiomyopathy, the degree of myocardial disarray, interstitial fibrosis, and nonhomogeneity of myocyte size showed positive correlations with cal-IB and negative correlations with cdv-IB. Conclusions: Ultrasonic tissue characterization with IB enables the noninvasive evaluation of myocardial histological abnormalities in patients with hypertrophic cardiomyopathy.

Optimal Antihypertensive Level for Improvement of Coronary Microvascular Dysfunction The Lower, the Better?

Recently, coronary microvascular function was documented to be impaired even in patients with prehypertension. However, the impact of antihypertensive level on improvement of coronary microvascular dysfunction in hypertensive patients remains to be established. We investigated the optimal blood pressure achieved with treatment of antihypertensive agents for improvement of coronary microvascular dysfunction in hypertensive patients. We prospectively studied 108 untreated hypertensive patients. All patients were treated with antihypertensive agents for approximately 12 months. Coronary flow reserve (CFR) was measured before and after treatment. The patients were divided into hypertensive, prehypertensive, and normal groups based on their average blood pressure during the treatment period. Pretreatment CFR was similar among all groups. CFR increased significantly in the normal group during the treatment period, but decreased significantly in the prehypertensive and hypertensive groups. This decrease was significantly greater in the hypertensive group than in the prehypertensive group. Multivariate analysis showed lowering blood pressure to normal level to be an independent determinant of improvement in CFR. The normal group was divided into normal-higher and normal-lower subgroups based on their average diastolic blood pressure during the treatment period. Increase in CFR was significantly greater in the normal-higher group than in the normal-lower group. These findings indicate that lowering blood pressure to a normal level is necessary to improve coronary microvascular dysfunction in hypertensive patients. Furthermore, raising diastolic blood pressure to a higher level within normal range has the most beneficial effect. However, as this study is based on observational design, it may have several limitations.

Atrial Involvement in Patients with Progressive Systemic Sclerosis: Relationship between Ultrasonic Tissue Characterization of the Atrium and Interatrial Conduction

Objective: The aim of this study was to assess atrial lesions using ultrasonic tissue characterization and to determine the contribution of atrial lesions to the interatrial electromechanical coupling conduction time in patients with progressive systemic sclerosis (PSS). Methods: Twenty patients with PSS and 20 age-matched healthy controls were evaluated. The cyclic variation in integrated backscatter value (CV-IB) was measured at the interatrial septum (IAS) from apical four chamber view. M-modes of ventricular long axis motion along with phono- and electrocardiograms were recorded simultaneously at the right lateral (RT) and left lateral (LT) sites of the atrioventricular (AV) rings and central fibrous body (CFB) in the apical four-chamber view. Intervals from the P wave on ECG to the echocardiographic onset of atrial contraction as a point of inflection in long axis M-mode echocardiogram were measured at the RT and LT sites of AV rings and CFB (P-RT, P-LT, P-SEP, respectively). Interatrial electromechanical coupling conduction time was determined as [(P-LT) – (P-RT)]. Results: In patients with PSS compared to normal controls, P-RT, P-SEP, P-LT, and interatrial conduction time were greater, while CV-IB in IAS decreased. Furthermore, CV-IB in IAS correlated well with interatrial conduction time (r = 0.7, p < 0.01) in patients with PSS. Conclusions: Interatrial electromechanical coupling times may be prolonged due to atrial tissue damage in patients with PSS.

Exercise-induced delayed onset of left ventricular early relaxation in association with coronary microcirculatory dysfunction in patients with diabetes mellitus.

BACKGROUND The initiation of ventricular diastole is an energy-dependent phase of cardiac cycle. Delayed onset of left ventricular (LV) relaxation has been proposed to identify myocardial ischemia. Diabetes mellitus (DM) is known to be associated with coronary microangiopathy, but its influence on LV early relaxation is not established. METHODS AND RESULTS Ninety-two subjects consisting of 70 DM patients without overt cardiac disease and 22 normal controls were evaluated. Using strain rate imaging, time from R-wave on the electrocardiogram to onset of LV relaxation (Tr) was measured at rest and peak exercise. Using myocardial contrast echocardiography, myocardial blood flow (MBF) was measured at rest and peak exercise, enabling MBF reserve. Tr at rest was similar between DM patients and controls, but Tr at peak exercise was significantly longer in DM patients than controls. MBF reserve was significantly reduced in DM patients compared with controls. There was a significant negative correlation between Tr at peak exercise and MBF reserve. In a multivariate analysis, MBF reserve was an independent determinant of Tr at peak exercise. CONCLUSIONS This study demonstrates that DM patients have exercise-induced delayed onset of LV relaxation in association with impaired coronary microcirculatory function in the absence of coexistent heart disease.