Iwao Sotobata

Effects of diltiazem on left ventricular diastolic behavior in patients with hypertrophic cardiomyopathy: evaluation with exercise pulsed doppler echocardiography

To estimate the effects of diltiazem on the left ventricular diastolic abnormalities in patients with hypertrophic cardiomyopathy, transmitral flow velocity during diastole was studied before and immediately after dynamic leg exercise with the pulsed Doppler technique combined with two-dimensional echocardiography. Seventeen patients with hypertrophic cardiomyopathy and 24 apparently healthy men performed bicycle ergometer exercise in the supine position with the target heart rate set at 120 beats/min. The patients with cardiomyopathy were directed to perform the exercise at the same intensity after receiving 30 to 60 mg of diltiazem, three times daily, for 1 or 2 weeks. The pattern of transmitral flow velocity in diastole had two components, one corresponding to the rapid filling phase in early diastole and the other to the atrial contraction phase in late diastole. To assess left ventricular diastolic behavior, the following variables were analyzed: peak velocity in the rapid filling and atrial contraction phases, the ratio of peak velocity in the atrial contraction phase to that in the rapid filling phase, and pressure half-time. The changes in peak velocity in the atrial contraction phase, pressure half-time and the ratio of peak velocity in the atrial contraction phase to that in the rapid filling phase with exercise differed significantly between patients with hypertrophic cardiomyopathy with no medication and control subjects. After diltiazem, the response of these variables to exercise was almost identical in the two groups. These results suggest that diltiazem can lessen the left ventricular diastolic abnormality in patients with hypertrophic cardiomyopathy on dynamic exercise of mild intensity.

Effects of a new vasodilator, nicorandil, on exercise-induced impairment of left ventricular function in patients with old myocardial infarction.

Hemodynamic effects of nicorandil on exercise-induced impairment of left ventricular function were studied in nine patients with old myocardial infarction but without angina pectoris. Hemodynamic data were obtained by symptom-limited supine multistage bicycle ergometer exercise testing before and 1 h after single oral administration of 15 mg of nicorandil. Systolic and diastolic blood pressure at rest decreased significantly after nicorandil administration (p < 0.01). A most remarkable change in the hemodynamic response to supine dynamic exercise after nicorandil was a decrease in pulmonary artery wedge pressure (both at rest and at peak exercise, p < 0.001). An index of cardiac function, obtained from the relation between pulmonary artery wedge pressure and left ventricular stroke work index, improved significantly after nicorandil. The ratio of pressure-rate product to coronary sinus flow, which is an index of the ratio of myocardial oxygen consumption to myocardial oxygen supply, decreased significantly (p < 0.05) after nicorandil administration. Reproducibility of the testings was also studied in six patients with old myocardial infarction. Invasive hemodynamic variables between two successive symptom-limited supine leg exercise testings, except pulmonary artery wedge pressure, were reproducible in patients with old myocardial infarction but without angina pectoris. Only pulmonary artery wedge pressure at rest in the second exercise testing showed a significantly lower value (p < 0.05). It is concluded that nicorandil is a useful drug for improvement of exercise-induced impairment of left ventricular function with an increase in myocardial oxygen supply.

Effects of a new second generation calcium channel blocker, nilvadipine (FR34235), on exercise-induced hemodynamic changes in stable angina pectoris.

The mechanism of the antianginal actions of nilvadipine was investigated in 11 patients with effort angina pectoris. Hemodynamic data were obtained by angina-limited supine multistage bicycle ergometer exercise testing before and after a single 6 mg dose of nilvadipine. Compared with chest pain during control exercise testing, pain at peak exercise disappeared or abated and the ST segment at peak exercise also showed less significant depression after administration of nilvadipine. At rest and at peak exercise, mean blood pressure, pulmonary artery wedge pressure and systemic vascular resistance decreased significantly, whereas heart rate and cardiac index increased significantly after nilvadipine. Rate-pressure product and stroke volume index did not change significantly. Coronary sinus flow at peak exercise increased significantly and total coronary vascular resistance at rest and at peak exercise decreased significantly after nilvadipine. The plasma concentrations of nilvadipine 1.5 hours after administration ranged from 1.15 to 8.23 ng/ml. These data suggest that the principal factors in the antianginal actions of nilvadipine are an increase in myocardial oxygen supply due to increased coronary blood flow and a reduction in myocardial oxygen demand mainly by a decrease in afterload and additionally by a decrease in preload.

Accuracy of cardiac output measured by continuous wave doppler echocardiography during dynamic exercise testing in the supine position in patients with coronary artery disease

To estimate the accuracy of cardiac output measured by continuous wave Doppler echocardiography from the suprasternal notch and the utility of this method for evaluating left ventricular function during dynamic exercise, simultaneous thermodilution and Doppler cardiac output were measured in 34 patients with coronary artery disease during multistage ergometer exercise in the supine position. Cardiac output was measured at rest and during each stage of exercise. Twenty-five of the 34 patients whose thermodilution curves were adequate for analysis were studied during exercise. The correlation coefficient for the two methods was 0.85 at rest and 0.84 during exercise. Differences between the two methods were not significant at rest but were significant during exercise, with the thermodilution method giving the higher values. Underestimation by the Doppler method is probably due to technical problems and changes in aortic diameter during exercise. The 25 patients were classified into two groups according to pulmonary artery wedge pressure at peak exercise. There were 11 patients in Group 1 pressure (greater than or equal to 20 mm Hg at peak exercise) and 14 in Group 2 pressure (less than 20 mm Hg at peak exercise). There were significant differences in the change in cardiac index and in peak aortic velocity from rest to peak exercise between the two groups. A significant linear correlation between the percent change in peak aortic velocity and in pulmonary artery wedge pressure from rest to peak exercise was observed (r = -0.66, p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Prognostic value of abnormal postexercisesystolic blood peessure response: Prehospital discharge test after myocardial infarction in Japan

To assess the prognostic value of an abnormal postexercise response in systolic blood pressure (SBP), treadmill exercise testing was performed in 217 survivors of acute myocardial infarction at an average of 9.3 weeks after infarction. During the mean follow-up period of 4 years, cardiac events were noted in 34 patients (16%), including cardiac death in 13 (6%), nonfatal reinfarction in 12 (6%), and coronary artery bypass graft surgery in nine (4%). An abnormal postexercise SBP response was defined as the ratio of SBP at 3 minutes of recovery to peak exercise SBP of 0.9 or more, on the basis of the cutoff point with the highest sensitivity and specificity to predict cardiac events. An abnormal postexercise SBP response occurred in 90 patients (42%). Patients with an abnormal postexercise SBP response had more exercise-induced myocardial ischemia. more left ventricular impairment, and more extensive coronary artery lesions than those without. Cox proportional hazards model demonstrated that the abnormal postexercise SBP response was ranked first in ability to predict cardiac death (p = 0.025, relative risk 15.41). Bypass surgery was associated with an abnormal postexercise SBP ratio (p less than 0.05). Nonfatal reinfarction could not be predicted by any clinical or exercise variables. In conclusion, an abnormal postexercise SBP response could be useful for predicting cardiac death and the need for bypass surgery after myocardial infarction. This response is probably the result of myocardial ischemia and left ventricular impairment.

Usefulness of rate responsive atrial pacing in patients with sick sinus syndrome.

We studied heart rate response and blood lactate changes during treadmill exercise testing in 10 patients with sick sinus syndrome (SSS) and normal atrioventricular (AV) conduction in whom an activity detecting multi‐programmable rate responsive pacemaker was implanted for atrial pacing (AAI pacing). Treadmill exercise testing was performed twice in each patient under the two different AAI pacing modes: rate responsive function off (fixed rate 60 pulses per minute [ppm]; RR‐off) and rate responsive function on (rate response 10, activity threshold medium, basic rate 60 ppm, and maximum rate 150 ppm; RR‐on). Chronotropic response and blood lactate change during exercise were compared among patients under each pacing mode and eight healthy volunteers of ages matching those of the patients. In patients under the RR‐off pacing mode (RR‐off patients), chronotropic response was lower (P < 0.01) and blood lactate level was higher (P < 0.05) than those in patients under the RR‐on pacing mode (RR‐on patients) and volunteers during exercise. In RR‐on patients, however, both chronotropic response and lactate level changes during exercise were comparatively improved, with no significant differences between RR‐on patients and volunteers. These data suggested that improvement of chronotropic response by rate responsive pacing, in comparison with nonrate responsive pacing, increased the blood supply to the working muscles and resulted in less lactate production during exercise. It was concluded that rate responsive AAI pacing which could maintain AV synchrony and normal intraventricular conduction was an optimal physiological pacing mode for SSS patients with normal AV conduction.

Correlation between the direction of the interventricular septum estimated with transmission computed tomography and the initial QRS vectors.

A correlative study was performed to relate the interventricular septal angle (As degrees) evaluated by transmission computed tomography to the azimuth of initial QRS vectors in 52 patients. Patients were divided into five groups: RV volume overloading (RVO), RV pressure overloading (RSO), LV volume overloading (LVO), LV pressure overloading (LSO), and normal control with no cardiopulmonary disease. For measurement of As degrees, the leftward and forward directions were designated as zero and 90 degrees, respectively. The mean value of As degrees was significantly smaller in RVO (14.4 degrees) and RSO (41.1 degrees) than in normal controls (50.4 degrees) and in LVO (53.2 degrees). The mean value of the azimuth of the initial 12-msec instantaneous QRS vectors (H 12 degrees) was significantly smaller in RVO (80.5 degrees), RSO (81.7 degrees), and LSO (81.3 degrees) than in normal controls (113.8 degrees and in LVO (113.7 degrees). A significant linear correlation was shown between As degrees and H12 degrees in a combined group consisting of RVO, LVO, and normal controls (r = 0.70, p less than 0.001), and also in another combined group consisting of RSO, LSO, and normal controls (r = 0.52, p less than 0.01). It was concluded that the orientation of the interventricular septum was one of the major determinants of the direction of initial QRS vectors, especially in patients with ventricular volume overload or without cardiopulmonary disease.

Recognition of myocardial infarction by means of Frank lead QR ratios

Abstract In 114 male patients with a well-documented history of acute myocardial infarction, the 3 orthogonal Frank system leads were analyzed for simple, manually measurable indices of infarction. The indices measured were the wave amplitudes of the QRS-T complex and the amplitude ratios of the Q, S, and T to the R wave. The recognition rate of infarction for each item was first evaluated using the 95 per cent normal limits determined from 155 normal men. The Q R ratio in Leads Z (56.1 per cent) and Y (48.2 per cent), the Qz amplitude (43.0 per cent), the T amplitudes, and the T R ratios in Leads X and Y (43.8 to 55.2 per cent) were found to be the most discriminative. The Q amplitude contributed practically nothing after screening with the Q R ratio. No significant correlation between any two of the 3-lead Q R ratios was observed. Hence, the 3-lead Q R limits with an equal false abnormality rate in normal subjects estimated from the respective probability density functions were combined to form a set of criteria. The recognition rate in the infarction series and the false abnormality rate in the normal controls of several sets of criteria are presented to allow for arbitrary selection of criteria appropriate to the purpose of screening. The set of Q R criteria with a false abnormality of 0.6 per cent in normal men has a sensitivity for recognition of infarction of 77.2 per cent. The information necessary for application of this new criteria can be obtained by single-channel electrocardiograph.

Evaluation of left ventricular diastolic filling by a pulse Doppler flowmeter in patients with coronary artery disease

Impaired left ventricular (LV) diastolic filling in patients with coronary artery disease (CAD) has been reported [1,2], and in these reports, the rate of changes in LV volume is used for the assessment of LV diastolic filling. However, in CAD, the calculation of LV volume is sometimes difficult because of the regional abnormalities of LV wall motion. The transmitral blood flow during diastole is equal to the rate of changes in LV volume in the absence of regurgitation or shunt flow into the LV, which is independent of the regional LV wall motion.

Continuous wave Doppler echocardiographic evaluation of cardiac output and its applications to treadmill exercise

To evaluate the clinical usefulness of Doppler-derived cardiac output and the effect of altered left ventricular function during maximal treadmill exercise, this study was performed using continuous wave (CW) Doppler technique through the suprasternal notch acoustic window. Subjects consisted of 22 patients with coronary artery disease (study 1) and 21 healthy male volunteers (study 2)