Mikio Mitsuoka

Response of the radial artery to three vasodilatory agents

We examined the response of the radial artery to vasoactive agents (isosorbide dinitrate, ISDN, 1 mg, 3 mg, and 5 mg; verapamil, 1 mg, 3 mg, and 5 mg; and lidocaine, 10 mg, 30 mg, and 50 mg) in 100 consecutive patients admitted for elective coronary angiography. The drug solutions were directly injected into the radial artery from the puncture site. As a result, 5 mg of ISDN increased the diameter of the radial artery by 31% and 28.8% at the proximal and distal sites, respectively. Similarly, 5 mg of verapamil increased it by 9% and 10.8% at the proximal and distal site, respectively. But 10 mg of lidocaine decreased it by −15.6% and −12.1% at the proximal and distal site, respectively. At the doses utilized, ISDN was the most potent vasodilator for the radial artery and lidocaine caused paradoxical vasoconstriction. Cathet. Cardiovasc. Intervent. 49:253–256, 2000.

Chaotic behavior of hemodynamics with ventricular assist system.

In order to analyze hemodynamic parameters during left ventricular assistance as an entity and not as decomposed parts, non-linear mathematical techniques were utilized. Pneumatically actuated ventricular assist systems (VAS) were implanted as left heart bypasses in acute animal experiments, using healthy adult mongrel dogs. By the use of the non-linear mathematical technique, the arterial blood pressure waveform (AP) was embedded into the four-dimensional phase space and projected into the three-dimensional phase space. The Lyapunov numerical method was used as an adjunct to the graphical analysis of the state space. The phase portrait of the attractor showed a complex structure; a three dimensional solid torus with a screw type structure as a part, suggesting deterministic chaos in the AP without left ventricular assistance. Positive lyapunov exponents confirmed the existence of chaos. During counterpulsation mode left ventricular assistance, the phase portrait of the attractor showed a more complex structure, and positive Lyapunov exponents suggested a greater dimensional deterministic chaos. However, non-structured patterns were seen in the phase space during internal mode VAS driving, suggesting the possibility of dissipative dynamics in the four dimensional phase space. These results suggest that the cardiovascular system with counterpulsation mode VAS driving is in a homeochaotic state, which is thought to be a flexible and intelligent control system. And there is greater dimensional complex dynamics in the circulatory regulatory system with VAD during internal mode assistance.

Renal Dysfunction on Admission as a Predictor for In-Hospital Mortality of Patients with Stanford Type B Acute Aortic Dissection

Stanford type A and open false lumen are accepted predictors for in-hospital mortality in patients with acute aortic dissection (AAD). However, the association of renal dysfunction on admission with in-hospital mortality is not well known. The aim of this study was to investigate the prognostic value of renal dysfunction in patients with AAD. A total of 250 patients with type B AAD admitted to our institution between January 2003 and August 2011 were enrolled in this study. In multivariate logistic regression analysis, the significant predictors of in-hospital mortality were age (odds ratio [OR] 1.575, 95% confidence interval [CI] 1.078-2.864, p = 0.024), maximum aortic diameter measured by an initial computed tomography (CT) (OR 1.740, 95% CI 1.029-2.940, p = 0.039), decreased enhancement of kidney (OR 7.716, 95% CI 2.335-25.501, p = 0.001) and estimated glomerular filtration rate (eGFR) <60 ml/min/1.73m(2) on admission (OR 2.782, 95% CI 1.062-7.283, p = 0.037). In conclusions the results identified a renal dysfunction on admission as the independent predictor of in-hospital mortality in type B AAD. Further investigations are needed to evaluate therapies and strategies for decreasing the deterioration of renal function to improve in-hospital mortality in patients with AAD.

Interatrial mechanical dyssynchrony shown by tissue doppler imaging during atrial flutter

Although regular supraventricular tachycardia is traditionally classified on the basis of P‐wave morphology, diagnostic accuracy is limited to information obtained from surface electrocardiography. Intracardiac electrophysiology is a conclusive although invasive diagnostic method. We report a case of regular supraventricular tachycardia with a heart rate of 162 bpm. M‐mode echocardiography of the interatrial septum clarified both the atrial rate and the ventricular response ratio. Tissue Doppler M‐mode imaging demonstrated the delay between the posterior wall motion of the left and right atrium. Although it deserves further study, transthoracic echocardiography may provide useful information in addition to electrocardiography.

Three-dimensional relationship between the conus branch and the precordial leads confirmed by 64–multidetector-row computed tomography

A 65-year-old man with effort angina pectoris underwent percutaneous coronary intervention of the proximal right coronary artery. The lesion was dilated with a bare-metal stent under wire protection of the conus branch (CB). However, the jailed CB was occluded. Electrocardiogram with conventional precordial leads (V(1) through V(6)) accompanied with the supplementary leads (V(1) through V(6)) positioned 1 intercostal space higher showed marked ST elevation in V(1) through V(3) that was more prominent in V(1) through V(3). The 64-multidetector-row computed tomographic coronary angiography showed recanalization of the CB located just in the center of the V(1), V(2), V(1), and V(2) electrodes.

Fractal Dimension Analysis of Chaos in Hemodynamics with Artificial Heart

To analyze the hemodynamic parameters in prosthetic circulation as a complete entity, not as a decomposed entity, non-linear mathematical techniques, including chaos and fractal theory, were utilized. Two pneumatically actuated ventricular assist devices were implanted as biventricular bypasses (BVB) in chronic animal experiments in four healthy adult goats. For the comparison between the natural and prosthetic circulation, the BVB type complete prosthetic circulation model with ventricular fibrillation was adopted. All hemodynamic parameters with natural circulation without BVB pumping and artificial circulation were recorded under awake conditions, and calculated with a computer system. By the use of a non-linear mathematical technique, arterial blood pressure waveform was embedded into the return map by the beat-to-beat variability, and fractal dimension analysis was performed to analyze the reconstructed attractor. By the use of the box-counting method, fractal dimension analysis of the hemodynamics was performed. The return map of the hemodynamics during natural and artificial circulation showed the characteristics of lower dimensional fractal. The fractal time series data were suggested to have robusticity and error resistance. Thus, our results suggest that the circulatory regulatory system with the artificial heart may have these desirable characteristics.