This study was undertaken to compare and re-examine the relation of lactate threshold (LT) and ventilatory threshold (VT), using six objective determination methods proposed previously. Twenty-one ...young male subjects performed a cycle exercise test in which the work rate was increased by 150 kg.m every 2 min up to his limit of volitional fatigue. Through each test, gas exchange parameter measurements were made every 1 min (every 30 s at nearly maximal level), and the venous blood samples were taken from a warmed ear lobe at each work rate for determining blood lactate concentration. LT and its variance were determined by the intersecting straight lines regression. LT ranged from 0.72 to 1.40 l/min in terms of VO2, and the mean value of S.D. for each LT was about 0.1 l/min. Each objective method for determining VT used in this study was based on the simple modelling of the criterion for visual detection of VT, that is the non-linear increase in VE or the systematic increase in VE/VO2. When the relationship between LT and VT was examined, VT by the objective methods based on determining minimum value of VE/VO2 showed relatively high consistency with LT. Of 16-20 individuals out of all 21 subjects, there were VT within LT +/- 0.2 in VO2. It is concluded that VE/VO2 is a more sensitive index for detecting VT than VE in the gas exchange parameters, and the objective VT determination method based on minimum value of VE/VO2 could facilitate estimation of LT within an error of +/- 0.2 l/min VO2 in most normal individuals.
The new system of cardiac wall kymography was proposed based on the results with our modified device. The cardiac wall motion kymography taken from a portion of the precordial area was examined for ...its ability to detect wall motion abnormalities. Furthermore, the 3 dimensional graphic display of the cardiac wall kymogram map was attempted by computer. This new approach looks promising because of the enhanced ability to recognize cardiac wall motion abnormalities in myocardial infarction.
An abnormal echocardiographic signal was detected in the myocardium on the echocardiographic examination of the septum and posterior left ventricular wall in a patient found to have lymphosarcoma ...which was diffusely infiltrated in the myocardium. This echocardiographic abnormality was well correlated with the autopsy findings. Echocardiography appears to be one of useful methods in diagnosing cardiac mural tumor antemortemly.
A comparison of the effects of several antiarrhythmic agents was made in a study of 70 patients - 15 with manifest Wolff-Parkinson-White (WPW) syndrome, 17 with concealed WPW syndrome, 18 with AV ...nodal re-entrant tachycardia, 14 with paroxysmal atrial fibrillation and 6 with paroxysmal atrial flutter - employing intracardiac stimulation and esophageal pacing. For the termination of paroxysmal supraventricular tachycardia, intravenous administration of verapamil or aprindine was more effective than that of disopyramide or procainamide. In AV nodal re-entrant tachycardia, verapamil was the most effective for termination. In the manifest WPW syndrome, disopyramide or aprindine was indicated especially for patients with the accessory pathways of the short antegrade refractory period, because these drugs lengthened the refractory period of the accessory pathways. For the purpose of converting atrial fibrillation or flutter to the sinus rhythm, type IA drugs such as disopyramide were indicated. However, verapamil was effective for slowing down the ventricular rate in atrial fibrillation or flutter except in cases of manifest WPW syndrome. A 6-month follow-up study showed that oral administration of verapamil was also useful for putting a stop to the attacks in 24 out of 32 patients with paroxysmal supraventricular tachycardia, while oral disopyramide prevented the recurrence of atrial fibrillation in only 4 of 10 patients.
Cardiac functions of 28 patients long after correction of tetralogy of Fallot (TOF) were examined using non-invasive and invasive methods. For comparison the patients were grouped in 2 different ...ways: those with a right ventricular systolic pressure below 50 mmHg (Group A, n = 10) and above 50 mmHg (Group B, n = 18) in the early post-operative stage ; those having an ability to complete the treadmill test (Group I, n = 14) and those without it (Group II, n = 10). The following results were obtained by our study performed more than 10 years after surgery : 1) Group A showed no differences in all parameters studied as compared with Group B. 2) As compared with the normal subjects ( control group, n = 20), the patients had a larger cardio-thoracic ratio (CTR) and a larger right/left ventricular dimension ratio (RVD/LVD), but showed no differences in percent fractional shortening (%FS), mean velocity of circumferential fiber shortening (mVcf), corrected ejection time (ETc) and ejection fraction(EF). 3) As compared with Group I, Group II had a larger CTR, a larger RVD/LVD ratio, and continued higher levels of the right/left ventricular systolic pressure ratio (RVP/LVP) and right ventricular pulmonary systolic pressure gradient (PG), but showed no differences in %FS, mVcf, ETc, EF and pulmonary artery pulse pressure/pulmonary arterial systolic pressure ratio. 4) Eight patients, all belonging to Group II, , had ventricular arrhythmia (Lown's grade 3 or 4). 5) Severe pulmonary regurgitation (PR) was noted in Group II. At a later time long after the correction of TOF, RVP, PG, PR and arrhythmia are considered to be important parameters for evaluating the cardiac status in this disorder.
Regurgitant flows in valvular diseases were evaluated by a pulsed Doppler flowmeter combined with an electronic beam sector scanning echocardiograph. The apparatus which was newly developed by us ...allowed the simultaneous demonstration of a sample site on a two-dimensional echocardiogram with flow measurement. Doppler signals of regurgitant flow were recorded as uni-directional or bi-directional wide frequency band signals. The locations, where regurgitant flow signals were detected, were depicted on the corresponding two-dimensional echocardiogram. This procedure was referred to as "a flow mapping technique" for non-invasive visualization of the distribution of regurgitant flow. In 12 patients with mitral regurgitation due to mitral valve prolapse detected by the pulsed Doppler technique, the regurgitant flow was distributed to the opposite side of the prolapsing mitral leaflet. The transmission of the regurgitant murmur was well consistent with the direction of the regurgitant flow. In 14 patients with aortic regurgitation, the distribution of aortic regurgitant flow visualized by the flow mapping technique closely coincided with that obtained by cineaortography. Based on the distribution of the regurgitation, the severity of the regurgitation could be precisely evaluated by the Doppler technique. Regurgitant flow signals were detected in the right atrium in all 13 patients with tricuspid regurgitation diagnosed by right ventriculography. We found 4 patients who did not show Carvallo's sign but in whom were detected regurgitant flow signals by the Doppler technique. In all of them, tricuspid regurgitation was proven at surgery. These results indicate that the Doppler technique presented here has an obvious clinical advantage in detecting and evaluating regurgitant flow in valvular diseases.
In evaluation of cardiac function by the non-invasive method, the possibility of separation of cardiac muscle performance from cardiac pump performance was studied. Among the non-invasive values, ...SV/ET, SV/(AO/EO), Pd/ICT, Pd/PEP, 1/ICT2, ET/PEP, and ET/ICT were considered as parameters for myocardial contractility. This research especially focused on Pd/ICT and ET/PEP. In auricular fibrillation it was possible to draw Starling-like curves and 3 dimensional coordinates to estimate a Vmax-like value. However this method could not be used in sinus rhythm. Whereas, in hypertension with abnormal afterload and uremia with abnormal preload, myocardial contractility was expressed by Pd/ICT under the influence of almost pure preload and ET/PEP under the influence of both preload and afterload. Therefore Pd/ICT was corrected with preload (AO/EO) and (Pd/ICT)/(AO/EO) may be used as the index for myocardial contractility.
Studies were performed to assess clinical applicability and usefullness of several non-invasive indices of myocardial contractility, especially, ET/PEP, Pd/ICT and (Pd/ICT)(AO/EO). In dogs preload, ...afterload or myocardial contractility was altered by durgs. The ET/PEP was influenced by preload as well afterload and PdICT by afterload, respectively. A correction of Pd/ICT with preload, (Pd/ICT)/(AO/EO)showed a satisfactory correlation to Vmas even when the preload and/or afterload were altered. In clinical cases, ET/PEP, Pd/ICT and (Pd/ICT)/(AO/EO) all changed following administration of positive inotropic substances. Moreover, in azotemic cases with primary change in preload the gradient of the Frank-Sterling's curve increased progressively and the entire curve was located upwards with increase of (Pd/ICT)/(AO/EO) value. In case of high-resistance type hypertension, nevertheless, (Pd/ICT)/(AO/EO) showed a tendency to change in association with alteration of its constituent factor Pd. Since there exists no absolutely perfect non-invasive index of myocardial contractility available for clinical application as yet, it would be appropriate to make overall evaluation of myocardial contractility by combined use of several indices, with underlying pathological conditions and characteristics of individual parameters taken into consideration.
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