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. AIM: In the present study, we evaluated electrogastrographic changes and heart-rate variability before and after the administration of nitrates. METHODS: In 15 patients with chest pain treated with nitrates, electrocardiography and percutaneous electrogastrography were performed before and after administration of nitrates. Autonomic nervous system function was evaluated by spectral analysis of heart-rate variability and serial changes in low frequency and high frequency power, and the low frequency/high frequency ratio were compared. Electrogastrograms were analysed by obtaining peak power amplitudes and their dominant frequencies. RESULTS: After the administration of nitrates (isosorbide dinitrate), high frequency power, an index of parasympathetic nervous activity, was significantly decreased, whereas the low frequency/high frequency ratio, an index of sympathetic nervous activity, was significantly increased. The mean peak amplitude of the electrogastrogram significantly increased postprandially both before and after treatment. After isosorbide dinitrate treatment, however, mean peak amplitudes after a meal were significantly lower than those obtained before treatment. The mean dominant frequency of the electrogastrogram did not vary before and after treatment. CONCLUSIONS: The present study suggests that nitrates inhibit gastrointestinal motility by decreasing autonomic nervous activity.

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 ischemia and reperfusion. This study aimed to evaluate the ability of candesartan to prevent fatal arrhythmias during acute myocardial ischemia 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 ischemia 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 ischemia and reperfusion, suggesting that candesartan can prevent the development of fatal arrhythmias.

Magnetic resonance coronary angiography in patients with ischemic heart disease: analysis of coronary arterial blood flow velocity pattern.

Only a few reports evaluating coronary arterial blood flow velocity patterns using magnetic resonance (MR) coronary angiography have appeared to date. This study reports an evaluation of coronary arterial blood flow velocity patterns in patients with ischemic heart disease and in healthy subjects using MR coronary angiography. The subjects consisted of 20 patients with ischemic heart disease (IHD group) and 20 normal healthy subjects (N group). Using the fCARD PC method, ECG-gated MR coronary angiography was performed using an anteroposterior opposing phased array coil. Regions of interest were placed on bilateral coronary arteries to measure coronary arterial blood flow velocity patterns. The IHD group was divided into two subgroups, based on the presence (MI group) or absence (AP group) of infarcted myocardium using 99m Tc-methoxyisobutylisonitrile (MIBI) myocardial scintigraphy. Average diastolic peak velocity (ADPV) was lower in the IHD group than in the N group. In addition, the diastolic / systolic velocity ratio (DSVR) was significantly lower in the MI group. Moreover, in the AP group, both the ADPV and DSVR values were significantly increased in those who had undergone percutaneous transluminal coronary angioplasty postoperatively. Different from the Doppler guidewire method, MR coronary angiography facilitates noninvasive evaluation of coronary arterial blood flow velocity. Therefore, these results indicate that MR coronary angiography represents a potentially useful technique for diagnosing lesions of coronary arteries and evaluating their functions. This noninvasive method can be expected to replace the invasive Doppler guidewire method in the near future with development of MR coronary angiography technology.

Patient with atrioventricular node reentrant tachycardia with eccentric retrograde left-sided activation: treatment with radiofrequency catheter ablation.

We describe a patient with supraventricular tachycardia with triple atrioventricular (AV) node pathway physiology. A discontinuous curve was present in the antegrade AV nodal function curves. During right ventricular pacing, the earliest retrograde atrial activation was recorded at the left-sided coronary sinus electrode. The retrograde ventricular-atrial interval was long and had decremental conduction. We induced a slow-slow AV node reentrant tachycardia (AVNRT) with eccentric retrograde left-sided activation. After slow pathway ablation, dual AV nodal pathway physiology was present. AVNRT with eccentric retrograde left-sided activation is relatively rare, and our findings suggest that eccentric retrograde left-sided atrial inputs consist partially of a slow pathway and disappear with slow pathway ablation.

Circulating adhesion molecules and severity of coronary atherosclerosis.

BACKGROUND: Circulating leukocytes are recruited at atherosclerotic sites through a family of adhesion molecules. Circulating forms of adhesion molecules in peripheral blood can be quantified now. OBJECTIVE: To evaluate the relationship between circulating adhesion molecules and severity of coronary atherosclerosis. METHODS: Subjects 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. RESULTS: Circulating 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. CONCLUSIONS: These 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.

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 immediately 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 normalized gray-level ratio. However, the remaining three dogs with a DSVR > or = 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 immediately after reperfusion may reflect myocardial microcirculatory injury.

The effects of nicorandil on electrophysiological changes in acute myocardial ischemia and reperfusion.

This study was undertaken to clarify the effects of nicorandil on electrophysiological changes during acute ischemia and following reperfusion. We prepared an acute ischemic heart model by ligating the left anterior descending coronary artery in 27 dogs. After 10 minutes, reperfusion was performed. The changes in ventricular effective refractory period (ERP) and intramyocardial conduction time (ICT) were compared between the nicorandil group (n = 12) which received nicorandil intravenously before the coronary ligation and the control group (n = 15). In the control group, the ERP was shortened during ischemia, and rapidly shortened immediately after reperfusion, but was slightly prolonged 10 minutes after reperfusion. The ICT was prolonged during ischemia, but returned to the pre-ischemia value after reperfusion. In the nicorandil group, the changes in ERP and ICT were significantly inhibited compared to those in the control group. The incidence of ventricular fibrillation (VF) during reperfusion was 42% in the control group. However, there was no VF during reperfusion in the nicorandil group. Therefore, nicorandil may correct both the delayed conduction and the uneven ventricular effective refractory period detected during acute ischemia and following reperfusion, inhibiting the development of ventricular arrhythmia during reperfusion.

Characteristics of coronary flow velocity in constrictive pericarditis.

A 50-yr-old man developed constrictive pericarditis following an episode of acute pericarditis. Cardiac catheterization revealed a typical early diastolic dip and plateau configuration in both the right and left ventricular pressure curves. The coronary flow velocity pattern determined using an intracoronary Doppler guidewire showed an abrupt decrease in peak velocity at early diastole and followed by plateau until late diastole, the so-called dip and plateau configuration. After a successful pericardiectomy, cardiac catheterization no longer showed the dip and plateau configuration, but the early diastolic dip in the coronary flow velocity persisted probably because of infiltration of the organic involvement into the myocardium.

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

BACKGROUND: It 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. METHODS: We 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. RESULTS: The 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. CONCLUSIONS: Coronary flow velocity patterns immediately after successful reperfusion appear to reflect the pathologic characteristics of the reperfused myocardium in dogs with AMI.

Right atrial potential profiles during atrial fibrillation predict the success of atrial defibrillation.

The right atrial electric potential was measured in 29 patients with chronic atrial fibrillation, and the clinical utility of these measurements in predicting the success of atrial defibrillation was investigated. The endocardial electric potential was recorded at 12 sites within the right atrium (high, middle, and low loci of anterior, posterior, lateral, and medial sites of the right atrium) with an electrode catheter. The duration and polar displacement of the atrial waves were measured at the one site that showed the maximum atrial electric potential among the 12 sites. The ratio of the maximum to the minimum atrial electric potential (atrial wave ratio) was calculated. Patients were classified into two groups according to the success (n = 6) or failure (n = 23) of atrial defibrillation. Electrophysiologic data were compared between the two groups, and correlations were evaluated between the data and the maximal left atrial diameter obtained from M-mode echocardiography. The two groups did not differ in the duration and polar displacement of the atrial waves. However, the atrial wave ratio was significantly lower in the success group than in the failure group, and the success rate of atrial defibrillation was also significantly greater in the patients with an atrial wave ratio of 10 or lower. This ratio showed a positive correlation with the maximal left atrial diameter; it became more difficult to achieve atrial defibrillation as the atrial wave ratio increased. Thus, the right atrial electric potential profile of patients with atrial fibrillation is a useful predictor of the success of atrial defibrillation.

Right and left ventricular wall motion velocities as diagnostic indicators of constrictive pericarditis.

The purpose of this study was to examine the usefulness of pulsed tissue Doppler imaging for diagnosing constrictive pericarditis. Motion velocities of the ventricular septum (VS) and left ventricular (LV) posterior wall along the short axis, and those of the anterior right ventricular (RV) wall, VS, and LV posterior wall along the long axis were recorded using pulsed tissue Doppler imaging in 12 patients with constrictive pericarditis, who were diagnosed by cardiac catheterization, and also in 20 normal subjects. Peak early diastolic and atrial systolic velocities (Ew and Aw, respectively) were calculated, and the time between the aortic component of the second heart sound and the peak of the early diastolic velocity (IIA-Ew) was determined. The peak Ew and II A-Ew along the short and long axes were significantly higher and shorter, respectively, in the patient group than in the normal group. In the patient group, the motion velocity of the VS along the short axis showed a "backward" motion with a sharp and marked peak velocity immediately before Ew, or a biphasic early diastolic wave; a clear "downward" motion immediately after Ew was observed in the motion velocities of the anterior RV wall, VS, and LV posterior wall along the long axis. These distinctive backward and downward motions were not observed in any of the ventricular walls of the normal subjects. In conclusion, the early diastolic RV and LV wall motion velocity patterns along the short and long axes as measured by pulsed tissue Doppler imaging provide important information for the diagnosis of constrictive pericarditis.

Electrophysiologic effects of quinaprilat in dogs during acute myocardial ischemia and following reperfusion.

BACKGROUND: There have been few studies concerning the electrophysiologic changes associated with the use of angiotensin-converting enzyme inhibitors in patients with acute myocardial infarction. We examined the electrophysiologic effects of quinaprilat in dogs during acute myocardial ischemia and following reperfusion. METHODS: The left anterior descending coronary artery was occluded for 10 min and reperfused for 10 min. Animals received intravenous quinaprilat (3 micrograms/kg per min, quinaprilat group) or saline (control group). We measured the ventricular effective refractory period and intra-myocardial conduction time within the left anterior descending coronary artery region (ischemic region) during myocardial ischemia and following reperfusion, and determined the frequency of ventricular fibrillation. RESULTS: The effective refractory period in the ischemic region decreased during myocardial ischemia and decreased further immediately after reperfusion in the control group. The intra-myocardial conduction time in the ischemic region increased during myocardial ischemia but rapidly shortened after reperfusion in the control group. In the quinaprilat group, however, no significant differences were evident between the ischemic and non-ischemic regions in either the effective refractory period or the intra-myocardial conduction time during myocardial ischemia or following reperfusion. The percentage shortening of the effective refractory period and the percentage prolongation of the intra-myocardial conduction time in the ischemic region were significantly lower in the quinaprilat group than in the control group during myocardial ischemia and following reperfusion. The frequency of ventricular fibrillation during myocardial ischemia and following reperfusion was significantly lower in the quinaprilat group (21%) than in the control group (74%; P < 0.01). CONCLUSIONS: Quinaprilat protects against electrophysiologic abnormalities, and may decrease arrhythmias during acute myocardial ischemia and following reperfusion.

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.

Efficacy of coronary angioplasty with a cutting balloon in a case of repeated coronary stenosis.

A 59-year-old man with a 90% stenosis of the left anterior descending coronary artery was treated with percutaneous transluminal coronary angioplasty (PTCA) using a conventional balloon. The stenosis recurred repeatedly and was retreated by PTCA three times. The stenosis again recurred, so coronary angioplasty using a cutting balloon was performed. During the present admission, we planned to place a coronary stent in the LAD to prevent restenosis. Anticoagulation is necessary after coronary stenting. However, anticoagulation was contraindicated in this patient because of ulcerative colitis. Therefore, coronary angioplasty using a cutting balloon was performed instead. The stenosis decreased from 90% to 25%, but a coronary dissection occurred. An angiogram performed 3 months later showed no stenosis, with resolution of the coronary dissection. The use of a cutting balloon preventing coronary artery restenosis following balloon angioplasty is a promising new technique which warrants further study.

[Usefulness of coronary angiography in patients undergoing carotid endarterectomy].

We evaluated 37 cases of coronary angiography in patients undergoing carotid endarterectomy (CEA). The severity of coronary stenosis was estimated by Gesini's scoring system. There was no correlation between the severity of carotid stenosis and that of coronary stenosis, but those patients who had a history of coronary artery disease, carotid bruit or intracranial artery stenoses presented significant severe coronary stenosis in most cases. Even in the patients who had no history of coronary artery disease (n = 26), 13 patients (50%) had stenotic lesions shown by coronary angiography. Eight patients required treatment for their coronary stenotic lesions: 5 were treated with percutaneous transluminal coronary angioplasty (PTCA) and 3 with coronary artery bypass grafting. Intraoperative occlusion tests monitored by EEG and SEP showed abnormal findings in 6 CEA operations. One of these patients received PTCA before CEA, and had a good clinical course during and after the CEA procedure. In conclusion, in patients undergoing CEA there is frequently concomitant coronary artery stenosis. We should thus assess the coronary artery lesion more precisely by coronary angiography, and should carry out prophylactic treatment for these lesions.

Noninvasive localization of accessory pathways by magnetocardiographic imaging.

The magnetocardiogram (MCG) is a newly developed method that helps localize a cardiac current source. To test the clinical accuracy of a 7-channel biomagnetic system in the localization of early ventricular depolarization sites, the MCGs of 14 patients with Wolff-Parkinson-White (WPW) syndrome were recorded in a radiofrequency-shielded room. The locations of early ventricular depolarization sites were classified by standard 12-lead electrocardiograms (ECGs) and body surface isopotential mapping. The accessory pathways of 3 patients with WPW syndrome were located in the right free wall and in 11 patients in the left free wall. The three-dimensional (3-D) dipole location was computed every 2 ms from the onset of the QRS complex by the least-square method. These 3-D dipole locations were projected onto a gated magnetic resonance image in order to visualize the propagation of the calculated ventricular source. The results were compared with those obtained by body surface isopotential mapping, and electrocardiographic and electrophysiologic studies. The location of the deduced current dipole at 20 ms correlated well with the location of the accessory pathway by the body surface mappings in 12 of the 14 patients with WPW syndrome. The MCG is capable of precisely determining the 3-D location of a current source in a noninvasive manner and may be of potential benefit in the treatment of WPW syndrome by catheter ablation.

Catheter ablation therapy in a case with WPW syndrome complicated by multiple tachyarrhythmias.

WPW syndrome is of importance because of the frequent association of tachyarrhythmias. However, its complication by 3 or more different tachyarrhythmias simultaneously is rare. This paper reports a case of WPW syndrome complicated by paroxysmal atrial fibrillation, atrial flutter, and 2 types of atrioventricular reentrant tachycardia. The tachyarrhythmias could be cured by cauterizing the accessory pathway using catheter ablation with radiofrequency electric current. A 30-year-old man visited to a local physician with an episode of tachycardia which failed to resolve, and a diagnosis of WPW syndrome associated with paroxysmal atrial fibrillation was made. The patient was referred to our hospital for further examination and treatment, and electrophysiological study was performed. During the examination, 2 types of atrioventricular reentrant tachycardia with different heart rates were induced, as well as atrial fibrillation and 2:1 atrial flutter. The presence of a left-sided accessory atrioventricular pathway was confirmed by coronary sinus mapping, and the following day catheter ablation was performed and the accessory pathway was cauterized. Subsequently, the delta wave disappeared from the ECG and no additional episodes of tachycardia occurred. Catheter ablation is still undergoing research as a therapeutic modality. However, because the ablation technique entails little invasion or risk, and is economical, it may well become a mainstream treatment for tachycardia in patients with WPW syndrome in the future.

Two sudden death cases of idiopathic ventricular tachycardia.

It is said that the prognosis of idiopathic ventricular tachycardia (IVT) without organic heart disease is good in general. In this paper, two sudden death cases of IVT are reported. The first case was a 44-year-old male, who was referred to our hospital for further examination and treatment of ventricular tachycardia. Echocardiography did not show obvious organic heart disease. After the patient was diagnosed with IVT, he was given drug therapy at the outpatient clinic. However, about six months later, he died suddenly while playing mahjong late at night. The second case was a 17-year-old male. He was also referred to our hospital by another hospital after being diagnosed with ventricular tachycardia. A diagnosis of IVT was made, for which he was given drug therapy at outpatient clinic. However, the patient discontinued receiving the drug therapy. The patient died suddenly about 3 months after discontinuation of the therapy. Some idiopathic ventricular tachycardia cases have poor prognosis like the present ones. It was considered necessary to thoroughly control and guide patients with their daily life and monitor them carefully about the ingestion of anti-arrhythmic agents.