Wave intensity, an index of ventriculo-arterial interaction, increases in hypertensive subjects but decreases in normotensive subjects during the cold pressor test.

PURPOSE: Cardiovascular reactivity to the cold pressor test (CPT) is considered to be a marker for apparent and potential hypertension. We aimed to elucidate the association between the changes in wave intensity (WI) during CPT and hypertension. METHODS: We recruited 85 volunteers, 33 of whom were hypertensive and 52 normotensive. Using ultrasonic equipment during CPT, we measured carotid arterial WI, which is defined in terms of blood pressure and velocity in the carotid artery. RESULTS: The peak WI (W1) increased during CPT in 70.6% of hypertensive individuals, but decreased in 72.6% of normotensive individuals. The chi-square (χ2) test showed that the association between the direction of change in W1 (increase or decrease) and the blood pressure (hypertensive or normotensive) was very strong (P < 0.0001). CONCLUSION: Direction of change in W1 during CPT is a clear marker to discriminate cardiovascular reactivity that does not vary depending on each investigator's subjective point of view.

Changes in cardiac contractility during graded exercise are greater in subjects with smaller body mass index, and greater in men than women: analyses using wave intensity and force-frequency relations.

INTRODUCTION AND PURPOSE: Estimation of the contractility of the left ventricle during exercise is an important part of the rehabilitation protocol. It is known that cardiac contractility increases with an increase in heart rate. This phenomenon is called the force-frequency relation (FFR). Using wave intensity, we aimed to evaluate FFR noninvasively during graded exercise. METHODS: We enrolled 83 healthy subjects. Using ultrasonic diagnostic equipment, we measured wave intensity (WD), which was defined in terms of blood velocity and arterial diameter, in the carotid artery and heart rate (HR) before and during bicycle ergometer exercise. FFRs were constructed by plotting the maximum value of WD (WD1) against HR. We analyzed the variation among FFR responses of individual subjects. RESULTS: WD1 increased linearly with an increase in HR during exercise. The average slope of the FFR was 1.0 ± 0.5 m/s3 bpm. The slope of FFR decreased with an increase in body mass index (BMI). The slopes of FFRs were steeper in men than women, although there were no differences in BMI between men and women. CONCLUSIONS: The FFR was obtained noninvasively by carotid arterial wave intensity (WD1) and graded exercise. The slope of the FFR decreased with an increase in BMI, and was steeper in men than women.

Wave Intensity Analysis: Sex-Specific Differences in Hemodynamic and Ventilatory Responses to Graded Exercise-Echocardiographic Measurements.

BACKGROUND: The differences in hemodynamic and ventilatory responses to graded exercise between men and women have not been well documented. Using wave intensity (WI) analysis, which is useful for analyzing ventriculo-arterial interaction, we aimed to elucidate the sex-specific differences. METHODS: We enrolled 48 healthy subjects (24 men and 24 women, age 21.3 ± 1.6 and 20.5 ± 0.9 years, n.s. [not significant]). Using ultrasonic diagnostic equipment, we measured WI, arterial stiffness parameter (ß), force-frequency relation (FFR) and other hemodynamic parameters in the carotid artery before and during graded bicycle exercise. We also analyzed expired gas volume (VE) during the exercise. The workload was increased stepwise by 20 W at 1-min intervals up to respiratory compensation (RC) point through the anaerobic threshold (AT). WI is defined as WI = (dP/dt) (dU/dt), where P is blood pressure, U is velocity, and t is time. The peak value of WI (W1) increases with left ventricular (LV) peak dP/dt, in other words, an index of cardiac contractility. The FFR was obtained as the linear regression line of W1 on heart rate. ß is defined as ß = ln (Ps/Pd)/[(Ds - Dd)/Dd], where D is the arterial diameter, and suffixes s and d indicate systolic and diastolic, respectively. RESULTS: There was no difference in the body mass index between men and women. Carbon dioxide outputs (VCO2) did not differ at rest, but those at AT and RC were greater in men. Oxygen consumptions (VO2) in men and women at rest did not differ, but those in men at AT and RC were greater. Workloads per body weight in men and women did not differ at AT, but they were greater in men at RC. Systolic pressures at rest, AT and RC were greater in men than women. Heart rates in men and women did not differ at any stage of the graded exercise. W1 did not differ at rest and AT, but it was greater in men than women at RC. The slope of the FFR during the period from rest to AT did not differ between men and women. However, the slope of the FFR during the period from AT to RC was greater in men. CONCLUSIONS: The reached values of workload/weight at RC, VCO2 at AT and RC, VO2 at AT and RC, W1 at RC, and the slope of the FFR during the period from AT to RC were greater in men than women.

Study of the Characteristics of Pulmonary Trunk in Pulmonary Hypertension Secondary to Left Heart Disease Using Pressure-Velocity Loops (PU-Loops).

Objectives: Although pulmonary hypertension (PH) caused by left heart disease (PH-LHD) is more common in PH, little is known about its properties of pulmonary artery (PA) in PH-LHD. The purpose of this study was to measure pulmonary regional pulse wave velocity (PWV) and to quantify the magnitude of reflected waves in patients with PH-LHD by the analysis of the pressure-velocity loops (PU-loop). Methods: High-fidelity PA pressure (Pm) and PA velocity (Vm) were measured in 11 subjects with PH-LHD (mean Pm>25 mmHg), 1 subject with atrial septal defect (ASD) without PH and 12 control subjects, using multisensor catheters. PWV was calculated as the slope of the initial part of the PU-loop in early systole. The similarity in the shapes of the pressure and flow velocity waveforms over one PU-loop was quantified as the magnitude of reflected wave by calculating the standard error of the estimate (Sy/x) from linear regression analysis between Pm and corresponding Vm. PWV and Sy/x during a Valsalva maneuver (VM) were also assessed in nine control subjects. Results: The contour of PU-loop was so characteristic between control and PH-LHD. Max. PWV (349 cm/s) was recorded in PH-LHD and min. PWV (111 cm/s) was recorded in ASD. VM increased Pm (12 [7-15] mmHg vs. 50 [18-110] mmHg; p=0.009) and PWV (200 [148-238] cm/s vs. 260 [192-306] cm/s; p=0.009) significantly without significant increase of Sy/x (19.6 [12.7-28.9]% vs. 28.2 [19.3-40.7]%; p=0.079). Although Sy/x was significantly higher in PH-LHD than in control and ASD (31.0 [14.3-36.3]% vs. 17.5 [8.4-28.9]%; p=0.009, ASD: 18.2%) , no significant difference was found in PWV between PH-LHD and control (269 [159-349] cm/s vs. 203 [154-289] cm/s; p=0.089). Conclusions: 1) The magnitude of wave reflection was elevated in PH-LHD significantly as compared with control and ASD. 2) Despite the significant increase in PA-PWV caused by abrupt elevation in Pm during VM in control, chronic elevation in Pm did not increase PA-PWV in PH-LHD significantly. It was hypothesized that the PA constituted a self-regulating system for maintaining the arterial stiffness stable against the chronic elevation in Pm in PH-LHD by a remodeling of increasing proximal pulmonary arterial crosssectional area gradually, which was compatible with the Moens-Korteweg equation. The PU-loop could provide a new simple and conventional method for assessing the pulmonary arterial properties, clinically. (This is a translation of J Jpn Coll Angiol 2016; 56: 45-53.).

Associations of increased arterial stiffness with left ventricular ejection performance and right ventricular systolic pressure in mitral regurgitation before and after surgery: Wave intensity analysis.

BACKGROUND: The effect of increased arterial stiffness on mitral regurgitation (MR) is not clear. Using wave intensity (WI) analysis, which is useful for analyzing ventriculo-arterial interaction, we aimed to elucidate associations of increased arterial stiffness with left ventricular (LV) ejection performance and right ventricular systolic pressure (RVSP) in MR. METHODS AND RESULTS: We noninvasively measured carotid arterial WI and stiffness parameter (ß) in 98 patients with non-ischemic chronic MR before and after surgery, and 98 age-and-gender matched healthy subjects by ultrasonography. WI is defined as WI = (dP/dt)(dU/dt) [P: blood pressure, U: velocity, t: time]. The peak value of WI (W1) increases with LV peak dP/dt. The temporal WI index (Q-W1)st, which is the standardized interval between the Q wave of the ECG and W1, is a surrogate for preejection period. Ejection fraction (EF), left atrial volume index (LAVI), effective regurgitant orifice area (ERO), RVSP, and other echocardiographic data were also obtained. W1 was enhanced in the MR group before surgery compared with the normal group (10.7 ± 5.7 vs 8.5 ± 3.6 × 103 mmHg m/s3, p < 0.05). However, the results of two-way ANOVA showed this enhancement of W1 was observed only in the subgroup of MR before surgery with lower arterial stiffness (ß < 13, p< 0.0001). ERO, ß and LAVI were predictor variables before surgery to determine RVSP. EF and (Q-W1)st before surgery were predictor variables for EF after surgery. CONCLUSIONS: In the MR group before surgery, increased arterial stiffness suppresses compensatory enhancement of W1, and increases RVSP. Prolonged (Q-W1)st has the potential for predicting low EF after surgery.

Noninvasive evaluation of left ventricular force-frequency relationships by measuring carotid arterial wave intensity during exercise stress.

BACKGROUND AND PURPOSE: Estimation of the contractility of the left ventricle during exercise is important in drawing up a protocol of cardiac rehabilitation. It has been demonstrated that color Doppler- and echo tracking-derived carotid arterial wave intensity is a sensitive index of global left ventricular (LV) contractility. We assessed the feasibility of measuring carotid arterial wave intensity and determining force-frequency (contractility-heart rate) relations (FFRs) during exercise totally noninvasively. METHODS: We measured carotid arterial wave intensity with a combined color Doppler and echo tracking system in 25 healthy young male volunteers (age 20.8 ± 1.2 years) at rest and during exercise. FFRs were constructed by plotting the maximum value of wave intensity (WD1) against heart rate (HR). RESULTS: We first confirmed that HR increased linearly with an increase in work load in each subject (r (2) = 0.95 ± 0.04). WD1 increased linearly with an increase in HR. The goodness-of-fit of the regression line of WD1 on HR in each subject was very high (r (2) = 0.48-0.94, p < 0.0001, respectively). The slope of the WD1-HR relation ranged 0.30-2.20 [m/s(3) (beat/min)]. CONCLUSIONS: Global LV FFRs can be generated in healthy young volunteers with an entirely noninvasive combination of exercise and wave intensity. These data should show the potential usefulness of the FFR in the context of cardiac rehabilitation.

Human abdomen recognition using camera and force sensor in medical robot system for automatic ultrasound scan.

Physicians use ultrasound scans to obtain real-time images of internal organs, because such scans are safe and inexpensive. However, people in remote areas face difficulties to be scanned due to aging society and physician's shortage. Hence, it is important to develop an autonomous robotic system to perform remote ultrasound scans. Previously, we developed a robotic system for automatic ultrasound scan focusing on human's liver. In order to make it a completely autonomous system, we present in this paper a way to autonomously localize the epigastric region as the starting position for the automatic ultrasound scan. An image processing algorithm marks the umbilicus and mammary papillae on a digital photograph of the patient's abdomen. Then, we made estimation for the location of the epigastric region using the distances between these landmarks. A supporting algorithm distinguishes rib position from epigastrium using the relationship between force and displacement. We implemented these algorithms with the automatic scanning system into an apparatus: a Mitsubishi Electric's MELFA RV-1 six axis manipulator. Tests on 14 healthy male subjects showed the apparatus located the epigastric region with a success rate of 94%. The results suggest that image recognition was effective in localizing a human body part.

Intermittent, moderate-intensity aerobic exercise for only eight weeks reduces arterial stiffness: evaluation by measurement of stiffness parameter and pressure-strain elastic modulus by use of ultrasonic echo tracking.

BACKGROUND AND PURPOSE: Aerobic exercise has been reported to be associated with reduced arterial stiffness. However, the intensity, duration, and frequency of aerobic exercise required to improve arterial stiffness have not been established. In addition, most reports base their conclusions on changes in pulse wave velocity, which is an indirect index of arterial stiffness. We studied the effects of short-term, intermittent, moderate-intensity exercise training on arterial stiffness based on measurements of the stiffness parameter (ß) and pressure-strain elastic modulus (E p), which are direct indices of regional arterial stiffness. METHODS: A total of 25 young healthy volunteers (18 men) were recruited. By use of ultrasonic diagnostic equipment we measured ß and E p of the carotid artery before and after 8 weeks of exercise training. RESULTS: After exercise training, systolic pressure (P s), diastolic pressure (P d), pulse pressure, systolic arterial diameter (D s), and diastolic arterial diameter (D d) did not change significantly. However, the pulsatile change in diameter ((D s - D d)/D d) increased significantly, and ß and E p decreased significantly. CONCLUSIONS: For healthy young subjects, ß and E p were reduced by intermittent, moderate-intensity exercise training for only 8 weeks.

Evaluation of exercise capacity using wave intensity in chronic heart failure with normal ejection fraction.

Impaired exercise capacity has been found in patients with diastolic dysfunction with preserved systolic function. Although conventional transthoracic echocardiography (TTE) provides useful clinical information about systolic and diastolic cardiac function, its capability to evaluate exercise capacity has been controversial. The inertia force of late systolic aortic flow is known to have a tight relationship with left ventricular (LV) performance during the period from near end-systole to isovolumic relaxation. The inertia force and the time constant of LV pressure decay during isovolumic relaxation can be estimated noninvasively using the second peak (W(2)) of wave intensity (WI), which is measured with an echo-Doppler system. We sought to determine whether W(2) is associated with exercise capacity in patients with chronic heart failure with normal ejection fraction (HFNEF) and to compare its ability to predict exercise capacity with parameters obtained by conventional TTE including tissue Doppler imaging. Sixteen consecutive patients with chronic HFNEF were enrolled in this study. Wave intensity was obtained with a color Doppler system for measurement of blood velocity combined with an echo-tracking system for detecting changes in vessel diameter. Concerning conventional TTE, we measured LV ejection fraction (EF), peak velocities of early (E) and late (A) mitral inflow using pulse-wave Doppler, and early (Ea) and late (Aa) diastolic velocities using tissue Doppler imaging. Left ventricular EF, E/A ratio, Ea, and E/Ea ratio did not correlate with exercise capacity, whereas W(2) significantly correlated with peak VO(2) (r = 0.54, p = 0.03), VE/VCO(2) slope (r = -0.53, p = 0.03), and ΔVO(2)/ΔWR (r = 0.56, p = 0.02). W(2) was associated with exercise capacity in patients with chronic HFNEF. In conclusion, W(2) is considered to be clinically more useful than conventional TTE indices for evaluating exercise capacity in patients with chronic HFNEF.

Clinical usefulness of wave intensity analysis.

Wave intensity (WI) is a hemodynamic index, which can evaluate the working condition of the heart interacting with the arterial system. It can be defined at any site in the circulatory system and provides a great deal of information. However, we need simultaneous measurements of blood pressure and velocity to obtain wave intensity, which has limited the clinical application of wave intensity, in spite of its potential. To expand the application of wave intensity in the clinical setting, we developed a real-time non-invasive measurement system for wave intensity based on a combined color Doppler and echo-tracking system. We measured carotid arterial WI in normal subjects and patients with various cardiovascular diseases. In the coronary artery disease group, the magnitude of the first peak of carotid arterial WI (W (1)) increased with LV max. dP/dt (r = 0.74, P < 0.001), and the amplitude of the second peak (W (2)) decreased with an increase in the time constant of LV pressure decay (r = -0.77, P < 0.001). In the dilated cardiomyopathy group, the values of W (1) were much lower than those in the normal group (P < 0.0001). In the hypertrophic cardiomyopathy group, the values of W (2) were much smaller than those in the normal group (P < 0.0001). In mitral regurgitation before surgery, W (2) decreased or disappeared, but after surgery W (2) appeared clearly. In the hypertension group, the magnitude of reflection from the head was considerably greater than that in the normal group (P < 0.0001). We also evaluated hemodynamic effects of sublingual nitroglycerin in normal subjects. Nitroglycerin increased W (1) significantly (P < 0.001). WI can be obtained non-invasively using an echo-Doppler system in the clinical setting. This method will increase the clinical usefulness of wave intensity.

Relationship between blood pressure obtained from the upper arm with a cuff-type sphygmomanometer and central blood pressure measured with a catheter-tipped micromanometer.

Recently, the importance of central blood pressure for cardiovascular risk stratification has been emphasized. Accordingly, the differences in peak systolic and bottom diastolic pressures between the ascending aorta and the brachial artery should be clarified. Study subjects consisted of 82 consecutive patients with suspected coronary artery disease who underwent cardiac catheterization, and in whom ascending aortic pressure waveform was obtained using a catheter-tipped micromanometer, and at the same time systolic and diastolic pressures were measured (single measurement) from the right upper arm with a cuff-type sphygmomanometer based on the oscillometric technique. No significant systematic difference (bias) was found between the peak pressure obtained in the ascending aorta and the systolic pressure from the right upper arm (133.6 +/- 25.1 vs 131.8 +/- 21.5 mmHg, not significant). Bland-Altman analysis showed only a small bias of +1.8 mmHg, and the limits of agreement were 25.4 mmHg and -21.8 mmHg. In contrast, the bottom pressure in the ascending aorta was significantly lower compared with the diastolic pressure from the upper arm (68.5 +/- 10.7 vs 73.0 +/- 12.4 mmHg, P < 0.0001). Bland-Altman analysis showed a small but significant bias of -4.5 mmHg, and the limits of agreement were 14.1 mmHg and -23.1 mmHg. The observed biases seemed to remain within practical range. However, random variation in the two measurements was rather large. This is considered to be caused by the random error in the single measurement with the cuff-type sphygmomanometer.

Different time course of changes in tricuspid regurgitant pressure gradient and pulmonary artery flow acceleration after pulmonary thromboendarterectomy: implications for discordant recovery of pulmonary artery pressure and compliance.

BACKGROUND: Pulmonary artery pressure (PAP) is reduced dramatically after pulmonary thromboendarterectomy in patients with chronic thromboembolic pulmonary hypertension (CTEPH). However, it is unclear whether pulmonary artery compliance increases in conjunction with the reduction in PAP. Pulmonary artery compliance may affect right ventricular afterload and prognosis. METHODS AND RESULTS: In 33 patients with CTEPH (9 men, 22-76 years), changes in the tricuspid regurgitation pressure gradient (TRPG) and the acceleration time (ACT) of pulmonary artery flow (a surrogate parameter of pulmonary artery compliance) were examined before and after pulmonary thromboendarterectomy using echocardiography to clarify factors affecting the changes. At 6 months, both TRPG and ACT normalized (or=100 ms, respectively) in 25 patients (group A) but not in 8 (group B). In group B, there were 5 with normal TRPG and shortened ACT at 6 months that normalized at 17+/-3 months. Group A patients showed shorter disease period and shorter period without anticoagulation than group B patients (p=0.04, 0.02 respectively). All patients in group A had the proximal type, and 2 patients of group B had the distal type (p=0.05). Clinical improvement was more remarkable in group A. CONCLUSIONS: The recovery of PAP and the ACT of pulmonary artery flow was not always concordant after pulmonary thromboendarterectomy, suggesting a presence of a time lag in the recovery between pressure and compliance in some patients. A long period of CTEPH, a long period without anticoagulation and the distal embolism type may be predictive factors of an unfavorable operative result with reduced pulmonary artery compliance, and hence poor recovery of clinical performance.

Effects of sublingual nitroglycerin on working conditions of the heart and arterial system: analysis using wave intensity.

PURPOSE: The effects of nitroglycerin (NTG) on the vascular system are well known. However, the effects of NTG on the heart are still obscure, because these effects are modified by those on the vascular system, and vice versa. Therefore, to evaluate the hemodynamic effects of NTG, it is important to understand the interaction between the heart and the vascular system. Wave intensity (WI) is a new hemodynamic index that provides information about working conditions of the heart interacting with the arterial system. The purpose of this study was to evaluate the interactive effects of NTG on the cardiovascular system in normal subjects using wave intensity. METHODS: We simultaneously measured carotid arterial blood flow velocity and diameter change using a specially designed ultrasonic system, and calculated the WI and the stiffness parameter ß. Measurements were made in 13 normal subjects (9 men and 4 women, aged 47 ± 10 years) in the supine position before and after sublingual NTG. RESULTS: The maximum value of WI (W 1) and the mid-systolic expansion wave (X) increased (W 1 from 9.1 ± 4.3 to 12.3 ± 5.5 × 10(3) mmHg m/s(3), P < 0.001; X from 105 ± 185 to 345 ± 370 mmHg m/s(3), P < 0.05). ß increased (from 10.5 ± 3.8 to 14.1 ± 3.8, P < 0.001). The pressure contours changed considerably. CONCLUSIONS: NTG increased W 1 and the mid-systolic expansion wave, which suggests enhanced cardiac power during the initial ejection and mid-systolic unloading. These results are new findings about the effects of NTG that can be added to the widely known late systolic unloading and preload reduction. NTG also increased arterial stiffness, which reduces the Windkessel function. By using an echo-Doppler system, WI can be obtained noninvasively. WI has the clinical potential to provide quantitative and detailed information about working conditions of the heart interacting with the arterial system.

Clinical usefulness of carotid arterial wave intensity in assessing left ventricular systolic and early diastolic performance.

Wave intensity (WI) is a novel hemodynamic index, which is defined as (d P/d t) x (d U/d t) at any site of the circulation, where d P/d t and d U/d t are the derivatives of blood pressure and velocity with respect to time, respectively. However, the pathophysiological meanings of this index have not been fully elucidated in the clinical setting. Accordingly, we investigated this issue in 64 patients who underwent invasive evaluation of left ventricular (LV) function. WI was obtained at the right carotid artery using a color Doppler system for blood velocity measurement combined with an echo-tracking method for detecting vessel diameter changes. The vessel diameter changes were automatically converted to pressure waveforms by calibrating its peak and minimum values by systolic and diastolic brachial blood pressures. The WI of the patients showed two sharp positive peaks. The first peak was found at the very early phase of LV ejection, while the second peak was observed near end-ejection. The magnitude of the first peak of WI significantly correlated with the maximum rate of LV pressure rise (LV max. d P/d t) (r = 0.74, P << 0.001). The amplitude of the second peak of WI significantly correlated with the time constant of LV relaxation (r = -0.77, P << 0.001). The amplitude of the second peak was significantly greater in patients with the inertia force of late systolic aortic flow than in those without the inertia force (3,080 +/- 1,741 vs 1,890 +/- 1,291 mmHg m s(-3), P << 0.01). These findings demonstrate that the magnitude of the first peak of WI reflects LV contractile performance, and the amplitude of the second peak of WI is determined by LV behavior during the period from late systole to isovolumic relaxation. WI is a noninvasively obtained, clinically useful parameter for the evaluation of LV systolic and early diastolic performance at the same time.

Delayed recovery of left ventricular regional work after coronary angioplasty in patients with opposite wall old myocardial infarction.

To evaluate the changes in left ventricular (LV) regional function during acute ischemia in patients with opposite wall old myocardial infarction (OMI), we examined LV regional work during percutaneous transluminal coronary angioplasty (PTCA) of the left anterior descending artery (LAD) in patients with a posterior OMI. Twelve patients with normal LV contraction (group A) and six patients with posterior OMI (group B) who were scheduled to undergo PTCA were enrolled in this study. All patients had single-vessel coronary artery disease and no collateral circulation. Sixty-second inflation was performed, and data were collected every 10 s. The regional work was calculated from the relationship between the mean wall stress and area strain. Regional work of the interventricular septum decreased after balloon inflation and was at its minimum at the end of inflation (group A: 0.6 +/- 0.3 mJ/cm(3); group B: 0.8 +/- 0.4 mJ/cm(3)). After balloon deflation, the septal regional work increased in both groups, and recovered to baseline at 40 s in group A and at 60 s in group B. Regional work of the posterior wall increased in group A after balloon inflation, but not in group B. The recovery of LV regional work after PTCA is delayed in patients with opposite-wall OMI.

A new noninvasive measurement system for wave intensity: evaluation of carotid arterial wave intensity and reproducibility.

Wave intensity (WI) is a new hemodynamic index that provides information about the dynamic behavior of the heart and the vascular system and their interaction. Carotid arterial wave intensity in normal subjects has two positive peaks. The first peak, W(1), occurs during early systole, the magnitude of which increases with increases in cardiac contractility. The second peak, W(2), which occurs towards the end of ejection, is related to the ability of the left ventricle to actively stop aortic blood flow. Between the two positive peaks, a negative area, NA, is often observed, which signifies reflections from the cerebral circulation. The time interval between the R-wave of ECG and the first peak (R - W(1)) corresponds to the pre-ejection period, and that between the first and second peaks (W(1) - W(2)) corresponds to ejection time. We developed a new ultrasonic on-line system for obtaining WI and arterial stiffness (beta). The purpose of this study was (1) to report normal values of various indices derived from WI and beta measured with this system, and (2) to evaluate the intraobserver and interobserver reproducibility of the measurements. The measurement system is composed of a computer, a WI unit, and an ultrasonic machine. The WI unit gives the instantaneous change in diameter of the artery and the instantaneous mean blood velocity through the sampling gate. Using these parameters and blood pressure measured with a cuff-type manometer, the computer gives WI and beta. We applied this method to the carotid artery in 135 normal subjects. The mean values of W(1), W(2), NA, R - W(1), and W(1) - W(2) were 8 940 +/- 3 790 mmHg m/s(3), 1 840 +/- 880 mmHg m/s(3), 27 +/- 13 mmHg m/s(2), 104 +/- 14 ms, and 270 +/- 19 ms, respectively. These values did not show a significant correlation with age. The mean value of beta was 10.4 +/- 4.8 and the values significantly correlated with age (men: r = 0.66, P < 0.0001; women: r= 0.81, P < 0.0001). The reproducibility was evaluated by intraobserver intrasession (IA), intraobserver intersession (IE), and interobserver intrasession variability (IO). The reproducibility of R - W(1) and W(1) - W(2) was high: the mean coefficient of variation (mCV) of IA was less than 3%; 95% confidence limits from the mean values (CL) were less than 8% for IE and less than 4% for IO. The reproducibility of W(1) and beta was good: mCV for IA was less than 10%; CL for IE and IO were less than 17%. W(2) and NA showed a higher variability than other indices: mCV for IA was less than 13%, and CL for IE and IO were less than 36%. However, two sessions by the same observer and two sessions by different observers were not biased. Wave intensity measurements with this system are clinically acceptable.

Nicorandil infusion leads to good recovery from ischemia of left ventricular regional work in comparison with nitroglycerin.

Nicorandil is an antianginal drug that exerts both a conventional nitrate effect and an independent ATP-dependent potassium channel-opening effect. The present study examined the effects of nicorandil on left ventricular regional work (RW) during coronary angioplasty in 22 patients with angina pectoris who were scheduled for angioplasty to the left anterior descending artery. The patients were randomly assigned to receive either nitroglycerin (group NG, n=12, 0.5 microg x kg(-1) min(-1)) or nicorandil (group NR, n = 10, 1.5 microg x kg(-1) min(-1)). Inflation was performed for 60 s and the data were collected every 10 s. The RW was derived from the relation between mean wall stress and area strain. The RW of the interventricular septum decreased after balloon inflation and was at its minimum after the 60s inflation (group NR: 1.24 +/- 0.72mJ/cm3, group NG: 0.63 +/- 0.25mJ/cm3). After balloon deflation, the septal RW of both groups increased, and recovered to the baseline condition at about 30s. At 20 s after deflation, the septal RW in group NR (3.58 +/- 1.17 mJ/cm3) was significantly higher than that in group NG (2.25 +/- 0.59mJ/cm3) (p < 0.05). An intravenous infusion of nicorandil led to good recovery of RW from ischemia compared with that obtained with nitroglycerin.

The mechanism of emergence and clinical significance of apically directed intraventricular flow during isovolumic relaxation.

The mechanism of emergence and the clinical significance of apically directed intraventricular flow during isovolumic relaxation were investigated. The relation between the spatial distribution of the flow and left ventricular (LV) apical wall motion abnormality, as well as LV performance, was studied in 97 patients who underwent cardiac catheterization for evaluation of chest pain. According to the distribution of the flow, the patients were classified into the following 3 groups: flow observed in the whole area between the tip of the papillary muscle and the apex (spread flow) (n = 38), flow observed in the same area that did not fill the whole area (localized flow) (n = 15), and no apparent flow observed in the area (without flow) (n = 44). An absence of flow disclosed apical asynergy with a sensitivity of 97% and specificity of 87%. The time constant of LV relaxation was significantly shorter in patients with spread flow than in those without flow. A significant difference was also observed in end-systolic volume index (18.8 +/- 6.8 vs 30.9 +/- 7.7 vs 42.3 +/- 20.2 mL/m(2), spread flow < localized flow < without flow, P <.05) among the 3 groups. The propagation velocity of LV early diastolic filling flow was significantly greater in patients with spread flow (47.0 +/- 8.3 cm/s) than in those with localized flow (30.7 +/- 7.8 cm/s) or without flow (28.6 +/- 7.8 cm/s) (P <.001). These findings indicate that the greater magnitude of LV elastic recoil and the faster LV relaxation in patients without LV apical asynergy produce apically directed intraventricular flow during isovolumic relaxation, enhancing the speed of LV early diastolic filling. Apically directed intraventricular flow during isovolumic relaxation may play an important role as a mediator of better LV systolic performance and LV relaxation to LV early diastolic filling. Absence of apically directed intraventricular flow during isovolumic relaxation is a manifestation of LV apical asynergy and global LV dysfunction from end systole to early diastole.