Akiyoshi Nishikado

Clinical application of pulsed Doppler tissue imaging for assessing abnormal left ventricular relaxation.

Conventional assessment of left ventricular (LV) relaxation by calculating the time constant of LV pressure decay during the isovolumic diastole requires an invasive approach. Conversely, noninvasive parameters obtained by measuring isovolumic relaxation time and transmitral flow velocity often give inaccurate information. Using LV pressure curve, pulsed Doppler echocardiography, and pulsed Doppler tissue imaging in 38 patients with heart disease and 12 control subjects, we calculated the time constant and recorded transmitral flow velocity and motion velocities at the endocardial portions of the ventricular septum and LV posterior wall. Compared with the controls, patients exhibited a prolonged time constant, a decreased peak early diastolic velocity of the LV posterior wall, and a prolonged time interval from the second heart sound to the peak of the early diastolic wave. The time constant correlated well with the isovolumic relaxation time and various parameters calculated from the transmitral flow velocity, except in patients with elevated LV end-diastolic pressure. In all subjects, the time constant correlated negatively with the peak early diastolic velocity of the posterior wall and positively with the time from the second heart sound to the peak of the early diastolic wave. Thus, early diastolic parameters derived from the motion velocity of the LV posterior wall by pulsed Doppler tissue imaging were closely related to the time constant. This technique may allow noninvasive evaluation of abnormal LV relaxation in patients with various heart diseases.

Circulating adhesion molecules and severity of coronary atherosclerosis.

BackgroundCirculating leukocytes are recruited at atherosclerotic sites through a family of adhesion molecules. Circulating forms of adhesion molecules in peripheral blood can be quantified now. ObjectiveTo evaluate the relationship between circulating adhesion molecules and severity of coronary atherosclerosis. MethodsSubjects included 81 patients undergoing diagnostic coronary angiography, 12 of whom had normal coronary arteries (control group). The remaining 69 patients with demonstrable coronary atherosclerosis were divided into two groups by use of Gensini scores, namely mild atherosclerosis (n=36, Gensini score 1–20) and severe atherosclerosis (n =33, Gensini score>20). Serum levels of circulating intercellular adhesion molecule‐1 (ICAM‐1), vascular cellular adhesion molecule‐1 (VCAM‐1), and E‐selectin of groups measured before angiography were compared. ResultsCirculating levels of ICAM‐1 in members of mild and severe atherosclerosis groups were significantly higher than those in members of the control group, whereas there was no significant difference among circulating levels of VCAM‐1 in members of the three groups. Circulating levels of E‐selectin in members of the mild atherosclerosis group were significantly higher than those in members of the severe atherosclerosis and control groups. ConclusionsThese findings suggest that E‐selectin is related to the early stage, and ICAM‐1 is related to the advanced stage, of coronary atherosclerosis. With progression of atherosclerosis, one‐step adhesion by ICAM‐1 could become more important than multistep adhesion involving E‐selectin, ICAM‐1, and VCAM‐1. These molecules may serve as markers for severity of coronary atherosclerosis.

Relation of Age and Sex to Atrial Electrophysiological Properties in Patients with No History of Atrial Fibrillation

Although atrial fibrillation is a common arrhythmia, especially in elderly men, little is known about age related changes in atrial electrophysiological properties or gender differences. The aim of this study was to analyze the effects of aging on vulnerability to atrial fibrillation and assessed gender differences in those age related changes. An electrophysiological study was performed on 73 patients with no history of atrial fibrillation, structural heart disease, or conditions with potential effects on cardiac hemodynamic or electrophysiological function, including 25 women (mean age 49 ± 18 years; range 12–84 years). The following atrial excitability parameters were assessed: spontaneous or paced (A1) and extrastimulated (A2) atrial electrogram widths, percent maximum atrial fragmentation (A2/A1 × 100) , effective refractory period, wavelength index (effective refractory period/A2), and inducibility of atrial fibrillation. There were no significant differences in percent maximum atrial fragmentation ( 143 ± 28 vs 142 ± 35% ), effective refractory period ( 241 ± 39 vs 238 ± 50 ms ), wavelength index ( 2.9 ± 0.8 vs 3.1 ± 0.9 ), induction of atrial fibrillation (10 [21%] vs 7 [28%]), or age ( 50 ± 17 vs 49 ± 20 years) between men and women. Age was not statistically different between those patients with and without induction of atrial fibrillation in men ( 48 ± 14 vs 50 ± 18 years ) and women ( 48 ± 18 vs 49 ± 21 years ). Percent maximum atrial fragmentation and effective refractory period were directly correlated with age in men ( r = 0.35, P = 0.01; r = 0.46, P < 0.001 , respectively) and women ( r = 0.42, P = 0.04; r = 0.45, P = 0.02 , respectively), though wavelength index did not correlate with age in men (r =−0.04) or women (r =−0.04) with no history of atrial fibrillation. Considering these findings, the authors conclude that the mechanism triggering atrial fibrillation may be different between older and younger patients with atrial fibrillation, because younger patients who have no marked substrate for atrial fibrillation may need many trigger beats to induce atrial fibrillation. (PACE 2003; 26:1238–1244)

Effects of angiotensin II type 1 receptor antagonist (Candesartan) in preventing fatal ventricular arrhythmias in dogs during acute myocardial ischemia and reperfusion

Fatal arrhythmias may be prevented by long-term oral administration of angiotensin-converting enzyme (ACE) inhibitors or angiotensin II type 1 (AT 1 ) receptor antagonists. However, there have been no studies evaluating the electrophysiologic changes that occur with the acute administration of AT 1 receptor antagonists during acute myocardial ische mia and reperfusion. This study aimed to evaluate the ability of candesartan to prevent fatal arrhythmias during acute myocardial ische mia and reperfusion. The left anterior descending (LAD) coronary artery was ligated for 10 min and then reperfused for 10 min in 45 adult mongrel dogs. Candesartan (1 mg/kg) or saline was administered intravenously 10 min before ligation of the LAD coronary artery (candesartan group [n = 20] and control group [n = 25], respectively). Changes in ventricular effective refractory period (ERP) and intramyocardial conduction time (ICT) in the risk area were compared during LAD occlusion and reperfusion. Ischemia-induced shortening of ERP was inhibited in the candesartan group compared with the control. There was a 4.7 ± 5.8% increase in ERP in the candesartan group, compared with a 11.5 ± 6.3% shortening in the control group (p < 0.01). Prolongation of ICT was inhibited in the candesartan group compared with the control group during both ische mia and reperfusion (maximal prolongation of ICT: 0.1 ± 3.0% vs. 37.7 ± 9.6%, respectively; p < 0.01). Incidence of ventricular fibrillation was lower in the candesartan group than in the control group (25% [5/20] vs. 72% [18/25], respectively; p < 0.01). Candesartan suppresses changes in ERP and ICT during acute myocardial ische mia and reperfusion, suggesting that candesartan can prevent the development of fatal arrhythmias.

Coronary flow velocity patterns immediately after reperfusion reflect the pathologic characteristics of reperfused myocardium in canine models of acute myocardial infarction

BackgroundIt is difficult to evaluate the extent of myocardial injury after successful reperfusion following acute myocardial infarction (AMI). We investigated the relationship between the coronary flow velocity pattern immediately after reperfusion and pathologic characteristics after myocardial reperfusion injury in dogs. MethodsWe measured distal coronary flow velocity variables in the left circumflex coronary artery in a canine model of AMI (n = 12) 10 min after the release of a clamp (3–10 h clamp procedure) using a 0.35 mm Doppler guide-wire. Dogs were divided into two groups according to presence or absence of early systolic retrograde coronary flow. Hearts were excised 2 h after reperfusion and examined histopathologically. ResultsThe clamping time tended to be longer in dogs with early systolic retrograde coronary flow. Neutrophil infiltration was observed in the myocardium of dogs without systolic retrograde flow (n = 9); hemorrhage was rarely detectable and the myocardium maintained a bundle form. However, the bundle form of the myocardium became rough, and the severity of the incidence of hemorrhage tended to increase as the ratio of the diastolic coronary flow velocity to systolic velocity (DSVR) decreased. Vacuolar degeneration of the myocardium was also observed in hearts with a relatively low DSVR. In the group with systolic retrograde flow (n = 3), hearts were characterized by coagulation necrosis, marked vacuolar degeneration of the myocardium and diffusely distributed red cells in the intermyocytes. Systolic antegrade flow velocity was much reduced in this group, resulting in a markedly increased DSVR. These findings appeared to be related to severe myocardial damage. ConclusionsCoronary flow velocity patterns immediately after successful reperfusion appear to reflect the pathologic characteristics of the reperfused myocardium in dogs with AMI. Coronary Artery Dis 9:21–27

Detection of coronary arterial microvascular disorders using 99mTc-tetrofosmin uptake increase during exercise and coronary blood flow velocity patterns obtained by magnetic resonance imaging

This study reports an evaluation of coronary arterial blood flow patterns in patients with diabetes mellitus and healthy subjects using magnetic resonance coronary angiography (MRCA). Twenty patients with diabetes mellitus (DM group) and 20 healthy subjects (N group) were studied using MRCA and myocardial SPECT images using 99mTc-tetrofosmin (TF). The rate of change in myocardial TF uptake was measured during a 1-day protocol of exercise and rest. Initial and delayed exercise single photon emission computed tomography (SPECT) images were acquired 30 min and 3 h after injection (370 MBq of TF) (TF1 and TF2, respectively). Thereafter, 740 MBq of TF was administered intravenously, again, and resting SPECT images (TF3) were acquired 30 min later. The myocardial counts of these three points of acquisition were defined, and the rate of change of myocardial TF uptake between exercise and rest was determined. The % increase in uptake was significantly lower in the DM group than in the N group in all myocardial segments. The average coronary arterial diastolic velocity determined using MRCA was slightly lower in the DM group than in the N group, and the average systolic peak velocity (ASPV) was slightly greater in the DM group than in the N group, although these values were not statistically significant. The diastolic/systolic velocity ratio (DSVR) in the DM group was significantly lower than that in the N group (P ≪ 0.05). There was a significant correlation between DSVR and % uptake increase (r = 0.605, P ≪ 0.05). These results indicate that the measurements made using MRCA and the % uptake increase measured using TF myocardial scintigraphy represent a potentially useful noninvasive method for diagnosing microvascular dysfunction in diabetic patients.

Coronary Flow Velocity Immediately After Reperfusion Reflects Myocardial Microcirculation in Canine Models of Acute Myocardial Infarction

Recent reports indicate that the coronary microcirculation is sometimes injured, despite successful reperfusion in acute myocardial infarction (AMI). However, it is difficult to evaluate the coronary microcirculation immediately after reperfusion by using only angiography. The purpose of this study was to examine the relationship between the pattern of coronary blood flow velocity and myocardial microcirculatory injury immedi ately after reperfusion in AMI. The authors recorded the left circumflex coronary flow velocity by using the Doppler guide wire method 10 minutes after reperfusion in a canine model of AMI. In addition, myocardial contrast echocardiography was performed with the injection of contrast medium into the left circumflex coronary artery before clamping of the coronary artery and 15 minutes after release of the clamp. From these images, the ratio of the normalized gray-level postreperfusion to preclamping in the contrast- enhanced area was determined. It was compared with coronary flow velocity variables. In the 10 dogs with a diastolic-to-systolic velocity ratio (DSVR) < 4.0, this velocity ratio 10 minutes after reperfusion correlated positively (r = 0.75, p < 0.01) with the normal ized gray-level ratio. However, the remaining three dogs with a DSVR ≥ 4.0 markedly deviated from this pattern. Coronary flow velocities in the three dogs were characterized by a greater decrease in systolic flow velocity and occurrence of early systolic retrograde flow. Myocardial contrast echocardiographic images in these three dogs demonstrated a lower normalized gray-level ratio. In conclusion, the coronary flow velocity pattern imme diately after reperfusion may reflect myocardial microcirculatory injury.

Efficacy and safety of rivaroxaban in extreme elderly patients with atrial fibrillation: Analysis of the Shikoku Rivaroxaban Registry Trial (SRRT)

BACKGROUND The Shikoku Rivaroxaban Registry Trial (SRRT) is a retrospective survey of the use of rivaroxaban for stroke prevention in elderly patients in Shikoku, Japan. METHODS The SRRT enrolled 1339 patients from 8 hospitals. Patients were divided into two groups according to their age, the extreme elderly group (453 patients aged ≧80 years) and the control group (886 patients aged <80 years). RESULTS In the extreme elderly group, 41.5% of the patients had low body weight (<50kg) and 65.1% had abnormal renal function (creatinine clearance <50ml/min). The mean CHADS2, CHA2DS2-VASc, and HAS BLED scores were 2.7, 4.4, and 2.3, respectively. There were 333 (73.5%) patients who met the dosing criteria, and of these patients, 81.2% received rivaroxaban 10mg daily. Thromboembolic events occurred in 4 patients (0.94%/person year) and intracranial hemorrhage occurred in 4 patients (0.89%/person year). The incidence of these events was not significantly different from the control group. In addition, all patients with cerebral infarction had been treated with a smaller dose of rivaroxaban than recommended by the dosing criteria, suggesting that dosing criteria should be adhered to. CONCLUSION These results suggest that rivaroxaban is effective and safe in extreme elderly patients with atrial fibrillation.

Impairment of gastrointestinal motility by nitrate administration: evaluation based on electrogastrographic changes and autonomic nerve activity

Background : Nitrates decrease the tone of the lower oesophageal sphincter, and may thus induce gastro‐oesophageal reflux.

A patient with Wallenberg’s syndrome induced by severe cough

A 45-year-old man developed severe cough with cervical pain. The patient was unable to hold an upright position. The origin of the right posterior inferior cerebellar artery was not enhanced by angiography. MRI showed a high signal intensity string-like structure of the right vertebral artery. In young patients, Wallenbergs syndrome related to mild head trauma has been reported. However, none of the previous studies related to vertebral arterial dissection was induced by severe cough. When cervical pain is present in young patients with severe cough, MRI should be performed to evaluate the possibility of vertebral arterial dissection.