Right ventricular myocardial infarction (RVMI) is not as rare as was previously thought and, if present, is almost always complicated with inferior myocardial infarction (IMI). On the basis of hemodynamic criteria. RVMI was identified in 33.7 percent of 98 cases with IMI. RVMI may induce a low cardiac output, if not often, resulting in cardiogenic shock. It is clearly desirable therefore to have an early and sensitive diagnostic clue to the presence or possibility of RVMI. Although much investigative attention in the diagnosis of RVMI has been focused on electrocardiography, echocardiography, radionuclide ventriculography, technetium-99 m stannous pyrophosphate scintigraphy, and thallium-201 scintigraphy. there has been little study of phonocardiography (PCG). The present study was therefore undertaken in an attempt to assess whether or not PCG information is useful for the indentification of RVMI. PCG recordings were made during unforced natural respiration for at least 8 consecutive beats. From among several PCG parameters, the ΔQP₂ interval was found to be the most reliable for the indentification of RVMI in patients with IMI. The ΔQP₂ interval was defined as the difference between Max QP₂ and Min QP₂, where Max QP₂ and Min QP₂ represent the maximal and minimal interval between Q and P₂, respectively. Using ΔQP₂ <__- 10 msec, the sensitivity and specificity for the diagnosis of RVMI were 90.9% and 84.6%, respectively. These results were superior to those obtained by radionuclide ventriculography, electrocardiography and echocardiography. We consider therefore that PCG should be recorded as soon as possible in the presence of IMI, and conclude that a small range (<__- 10 msec) of ΔQP₂ carries a reasonably high sensitivity and specificity for the diagnosis of RVMI.

抄録全体を表示

To determine indications for isoproterenol and norepinephrine, the effects of each drug on acute pulmonary embolic shock were compared with those of mechanical occlusion of the descending aorta (AO). In 18 dogs, we measured the changes in the hemodynamics and the ventricular wall motion in experimental pulmonary embolic shock. When the left ventricular systolic pressure decreased to 70 mmHg (shock), dogs were treated with isoproterenol, norepinephrine or AO. At the shock, the difference between the left and right ventricular pressures became negative. The changes in the left and right ventricular septum-free wall diameter (LVD. RVD) resulted in a significant leftward shift of the interventricular septum (IVS), and systolic shortening in LVD was extremely diminished. Isoproterenol administration decreased left and right ventricular end-diastolic pressure (LVEDP. RVEDP), but did not improve the reversion in RVEDP and LVEDP. The leftward shift of the IVS was not restored to normal. Following either norepinephrine administration or AO, the difference between the left and right ventricular pressures was restored to normal. Improvements in left ward shift of the IVS and systolic shortening of each diameter were observed. The similarity of norepinephrine administration to AO suggests that in the treatment of acute pulmonary embolic shock, restoration of systemic pressure for the maintenance of coronary perfusion, may be of primary importance. We concluded that norepinephrine is superior to isoproterenol for improvement of hemodynamics and ventricular wall motion in severe pulmonary embolic shock.

抄録全体を表示

The effects of intermittent coronary sinus occlusion (ICSO) on the size of myocardial infarction and reperfusion hemorrhage was evaluated. In Protocol 1, 8, dogs with ICSO and 8 controls underwent 4h of occlusion of the left anterior descending coronary artery. The same number of dogs underwent 4h of occlusion followed by 1h reperfusion in Protocal 2. The ICSO was started 1h after the ligation and continued through the occlusion period. There was no difference between the ICSO and the control group in hemodynamics and regional myocardial blood flow using hydrogen clearance method. However, ICSO did accelerate the rate of decline in intramyocardial CO₂ tension. The half life of CO₂ tension was 256±106 min in the control group but 139±34 min in the ICSO group (p<0.01). Lactate extraction rate showed the improving tendency during ICSO period. The ICSO resulted in a 50% and 80% reduction on an average in the size of infarct and reperfusion hemorrhage, respectively. We conclude that ICSO has prospective effects on myocardial ischemia with promise for clinical application.

抄録全体を表示

In order to obtain fundamental information about the developmental mechanisms of myocardial fibrosis in chronic hypertension, the hearts of male spontaneously hypertensive rats of the stroke-prone strain (SHRSP) and Wistar rats of the Kyoto strain (WKY) were histologically and histometrically examined. Fibrosis was a prominent histological feature of the hearts in SHRSP. It consisted of focal, interstitial, and perivascular fibrosis. For histometrical analysis the percentage areas of interstitial and perivascular fibrosis were calculated by using a color image processor. The percentage area of myocardial fibrosis increased with advancing age in both SHRSP and WKY. However, it was significantly higher in SHRSP than in WKY at 18 and 30 weeks of age. In SHRSP perivascular fibrosis of small arteries had already appeared at 8 weeks of age, while perivascular fibrosis of arterioles and interstitial fibrosis developed later. It is supposed that perivascular as well as interstitial fibrosis is induced by the exudation of some growth factors due to an increased vascular permeability. On the other hand, the focal fibrosis observed in old SHRSP is suspected to occur as a result of injury in myocardium due to stenosis or occlusion of vessels.

抄録全体を表示

Effects of temperature, contracton frequency, and intraatrial pressure on immunoreactive ANP release were investigated in isolated rat hearts perfused in Langendorff or working mode. A reduction of temperature from 37 °C to 27 °C caused a decrease of ANP release by 64% indicating its marked temperature-dependency (Q₁₀=2.92). An increase of atrial contraction frequncy from 300 to ₅00/min in Langendorff-perfused hearts did not cause a significant change in the ANP release. An elevation of left atrial filling pressure of working hearts from 8 to 18 and 28 cm H₂O was associated with pressure-dependent, and reversible increase of the ANP release. This pressure-induced release of ANP was inhibited in a low calcium (50% Ca²⁺) medium or by nifedipine (10^-7M). N-(6-aminohexyl)-5-chloro-1-naphthalene-sulfonamide (W-7, 10^-7M), a potent calmodulin inhibitor, or ryanodine (10^-8M) had similar inhibitory action against the pressure-induced increase of ANP release. These results indicate that ANP sectetion is primarily regulated by mechanical stretch or distension of the atrial wall, while the atrial contraction frequency is less important as a physiological stimulus for the secretion. The stretch-induced ANP secretion may reqiure an influx of calcium through the voltage-dependent Ca²⁺ channels. It was also suggested that Ca²⁺ release from the sarcoplasmic reticulum leading to an activation of calcium-calmodulin kinase may be included in the intracellular processes of ANP release by mechanical stretch.

抄録全体を表示

The incidence and the direct cause of syncope in ventricular tachycardia (VT) among patients with old myocardial infarction (OMI, n = 48), dilated cardiomyopathy (DCM, n = 18) and no evidence of heart disease (IVT, n=43) were compared. The presence or absence of syncope in each patient was surveyed by a standardized questionaire and a variety of electrocardiographic parameters for aggravating arrhythmias were measured. Syncope occurred in 19 of 43 OMI patients (40%). in 5 of 18 DCM patients (28%) and 6 of 43 IVT patients (14%) and significantly more often in OMI than IVT (p<0.01). Ventricular fibrillation (VF) was confirmed in 14 of the 19 OMI patients with syncope, in 3 of the 5 DCM patients with syncope and 1 of 6 IVT patients with syncope. The incidence of VF was significantly higher in OMI than in IVT (p<0.01). Mean VT cycle lengths (VTRR'm) in OMI patients with and without syncope were 0.35±0.07 sec and 0.42±0.10 sec. respectively (p<0.05). VTRR'ms in DCM patients with and without syncope were 0.₃±0.10 sec and 0.42±0.10 sec, respectivrly (NS). VTRR'ms in IVT patients with and without syncope were 0.27±0.04 sec and 0.41±0.10 sec, respectively (p<0.01). The results show that the high frequency of VT rate was the main cause of syncope in IVT. while VF was the main cause of syncope in OMI. There were no significant differences in the coupling interval, prematurity index, vulnerability index and QTc between groups with and without syncope in any of the underlying diseases. There were also no significant differences in the ejection fraction between the 2 groups. Therefore, it is considered that there is a diffrence in the direct cause of syncope between VT patients with OMI and IVT. Impaired ventricular function was not an important factor of syncope. Both VF and rapid VT are the main causes of syncope in OMI, while rapid VT is the main cause of syncope in IVT. This may be one of the reasons why IVT patients generally do not experience sudden cardiac death.

抄録全体を表示

We studied, prospectively, the predictive value of late potentials to cardiac sudden death and sustained ventricular tachycardias in 385 patients with myocardial infarction surviving over 4 weeks. Signal averaged electrocardiogram was performed over a 4 week period from the onset of acute myocardial infarction in all patients. Late potentials were observed in 118 of 385 patients. During the mean follow up period of 24.3 months, 17 patients had cardiac sudden death and 15 patients had symptomatic sustained ventricular tachycardias. In 16 of 17 patients with cardiac sudden death and 14 of 15 patients with sustained ventricular tachycardias, late potentials were observed. Sensitivity. specificity. positive predictive value, negative predictive value. and predictive accuracy of late potentials to cardiac sudden death in these 385 patients were 94.1%, 72.3%, 13.6%. 99.6% and 73.2% respectively. Also, these predictive values of late potentials to sustained ventricular tachycardias in the group of patients were 93.3%, 71.9%, 11.9%, 99.6% and 72.7%, respectively. We concluded that the clinical usefulness of late potentials in patients with myocardial infarction surviving over 4 weeks in the negative predictive value to cardiac sudden death and sustained ventricular tachycardias is superior to that of positive predictive value. Sensitivity of late potentials to these events is also higher.

抄録全体を表示

The prognostic significance of drug therapy based on the electrophysiologic study (EPS) was examined during a mean follow-up period of 32 months in 45 patients with sustained ventricular tachycardia (SVT) and in 87 with nonsustained VT (NSVT), and in 7 survivors of cardiac arrest. The drug treatment during the follow-up period was divided into EPS-guided therapy and empirical therapy; in the former therapy, an effective drug for prevention of induced VT by EPS was given and in the latter therapy, an empirical drug was used because there was no effective drugs by EPS. Occurrence of SVT or sudden cardiac death was considered as an arrhythmic event. Of 45 patients with SVT, Group I consisted of 32 cases with organic heart disease (OHD) and Group II. 13 without OHD. In Group I, arrhythmic event occurred in only 2 of 15 patients with EPS-guided therapy, whereas 9 of 13 cases with empirical therapy had arrhythmic event (p<0.01). In Group II, no arrhythmic event was observed in the 9 patients with EPS-guided therapy, whereas it was seen in 3 of the 4 patients with empirical therapy (p<0.05). Of 87 patients with NSVT, 61 cases had OHD (Group III). SVT was induced by EPS in 13 patients in Group III. Arrhythmic event was not observed in 8 patients with EPS-guided therapy, whereas it was seen in 3 of the 5 patients with empirical therapy (p<0.05). Arrhythmic event occurred in 2 survivors of cardiac arrest who underwent empirical therapy. These results suggest that EPS is a useful method for the prediction of life-threatening arrhythmias and for the selection of optimal drugs to prevent these arrhythmias.

抄録全体を表示

The study group consisted of 26 patients with a history of documented Torsade de Pointes (TdP) who were divides into 3 groups according to the causes of TdP. Group I consisted of 5 patients with congenital long QT syndrome. Group II consisted of 15 patients with TdP caused by antiarrhythmic drugs. Group III consisted of 6 patients with TdP caused by bradycardia resulting from third degree atrioventricular block. The QT interval was determined from a 12-lead electrocardiogram. Monophasic Action Potential (MAP) was recorded by a 6 F USCI electrode catheter. Isoproterenol infusion resulted in TU abnormality in all patients in Group I and induced a hump at phase 3 slope of MAP in all 3 patients tested. The QT interval change before and after IA administration was significantly larger in Group II patients compared to those without TdP (0.132±0.062 vs 0.029±0.31 sec, <0.005). Injection of 100 mg. of disopyramide in 2 patients in Group II resulted a hump at phase 3 slope of the MAP in both of them. The QT prolongation associated with decreasing the pacing rate from 70 to 50/min was significantly larger in patients with Group III compared to patients with bradycardia but without TdP (0.02±0.04 vs 0.07±0.05 sec, <0.005). The results suggests: l) different approaches are necessary for evaluation of TU abnormalities in patients with TdP according to the causes of TdP. 2) MAP might be a useful method for evaluating TU abnormality in patients with TdP.

抄録全体を表示

Paroxysmal atrial fibrillation (PAF) in patients with manifest WPW syndrome can be a life-threatening arrhythmia by deterioration into ventricular fibrillation. In patients with asymptomatic WPW pattern. the first PAF may lead to ventricular fibrillation or sudden death. Therefore, the purpose of this study was to predict a fatal PAF in patients with asymptomatic WPW pattern. The patient population was divided into two groups: (1) 145 patients with manifest WPW syndrome. excluding intermittent ones (32 with an episode of PAF. 49 with AV reciprocating tachycardia alone, and 64 without any episode of paroxysmal tachyarrhythmia), and (2) mixed group of patients with and without WPW syndrome (36 with an episode of PAF and 66 without PAF). The results were as follows: (1) (a) out of 32 patients with WPW syndrome and PAF, 8 patients were observed to have both the shortest preexcited R-R interval of less than 200 msec during PAF and the shortest antegrade effective refractory period of the accessory pathway (ERP-AP) of less than 250 msec, 7 of whom had dizziness or syncope during PAF and 2 died suddenly during the follow-up period; (b) 21 (32.8%) out of 64 patients with asymptomatic WPW pattern showed the shortest antegrade ERP-AP <250 msec; (2) patients with PAF had a higher tendency to develop repetitive atrial firing (RAF), as well as fragmented atrial activity (FAA), which were induced using programmed atrial stimulation. If a positive test result was defined as the induction of RAF and FAA, the positive predictive value was 63% and negative predictive value 79%. In conclusion, (1) having both the shortest R-R interval of less than 200 msec during PAF and the shortest antegrade ERP-AP of less than 250 msec might be a criterion for the identification of high risk in patients with WPW syndrome and PAF. (2) electrophysiologically revealed latent risk was observed in about one third of the patients with asymptomatic WPW pattern. in whom the ERP-AP was very short. (3) in these asymptomatic patients with combined RAF and FAA. the positive test result of atrial vulnerability might be of use to predict a fatal atrial fibrillation.

抄録全体を表示

Sixty-five patients (pts) with sustained ventricular tachycardia (VT) and 1 patient with symptomatic nonsustained VT were included in this study. Of these, 5 had died before electrophysiologic study (EPS) or determination of effective antiarrhythmic drugs. Inducibility of VT by our protocol varied from 69 to 100% according to underling diseases. Drug efficacy was evaluated by using conventional drugs in all and using flecainide and amiodarone in some. However, more than 50% of pts with inducible VT were found to be resistant to pharmacological therapy. Fourteen of 26 pts with drug-refractory VT, underwent surgical therapy. In all pts, the site of VT origin was determined and VT was either eradicated or clinically controlled in 86% of the patients. Catheter ablation was tried in 9 pts at the earliest activation site of VT or at the site where pace-mapping produced the best result in configuration in the QRS complex as the clinical VT. Prophylactic effect was confirmed in 60% but VT recurred in 3 pts. These VT became responsive to anti-arrhythmic drugs in 2 pts. In thirteen pts who died suddenly during the follow up period, none had adequate antiarrhythmic drugs. One patient died after operation because of residual VT among four different QRS morphologies found preoperatively. In conclusion, the success rate antiarrhythmic drug prophylaxis against VT induction or recurrence did not exceed 50%, therefore non-pharmacological interventions such as surgery or catheter ablation may be required.

抄録全体を表示

Map-guided direct surgery was performed in 408 patients with various tachyarrhythmias at our institution. Of 355 patients with WPW syndrome, 5 had experienced an episode of ventricular fibrillation (Vf). 180 had atrial fibrilllation with a rapid ventricular response, and 76 had other heart diseases. These patients were regarded as being at risk for sudden death. The shortest R-R interval between pre-excitation (215±38 msec) was significantly shorter than the antegrade effective refractory period (270±35 msec) of accessory pathway (ACP) in 126 patients (p<0.001). The shortest R-R interval of the patients with Vf was 200 msec or less. The ACP was successfully interrupted in 334 patients (94%). Simultaneous operations were carried out for other types of heart disease in 58 patients. Surgery was performed in 43 patients with ventricular tachycardia (VT). 39 non-ischemic and 4 ischemic, who were unresponsive to conventional antiarrhythmic therapy. Three patients with non-ischemic VT required emergency operation. The principle of surgery for non-ischemic was excision plus cryocoagulation of right ventricle and incision plus cryocoagulation of left ventricle. Thirty non-ischemic patients (76.9%) were cured of VT, while 7 still take medication prophylactically (3 for sporadic premature beats, and 4 for VT). All 4 patients with ischemic VT were also treated successfully. In conclusion, our results demonstrate the therapeutic value of map-guided direct surgery for life-threatening arrhythmias.

抄録全体を表示

We studied the factors determining the extent of myocardial damage induced by catheter electrical ablation in 23 mongrel dogs and evaluated the efficacy and safety of catheter electrical abation in 6 patients with medically refractory ventricular tachycardias (VT). Electrical shocks were delivered on the epicardium (EPI) and endocardium (END) of the ventricular wall of open-chest anesthetized dogs through a 6F USCI electrode catheter. Effect of the extent of electrode contact pressure was examined by the presence or absence of monophasic action potential using the contact electrode technique. The former was defined as the hard touch condition and the latter was defined as the soft touch condition. The myocardial lesion induced by EPI fulguration was larger than that by END fulguration (EPI-100 J soft touch: 10.2±2.9mm in diameter. 6.6±1.6mm in depth vs END-100 J soft touch: 7.7±1.7mm in diameter, 5.0±1.2 mm in depth; p<0.05, p<0.05). The lesion diameter and lesion depth were enlarged by increasing the amount of delivered energy. The lesion depth by the hard touch condition was significantly greater than that by the soft touch condition. The transmural perforation was observed in all EPI fulguration in the hard touch condition of the right ventricular wall. In the clinical study, one to three shocks (mean 1.8±0.7) of 60 to 200 J (maen 151±48 J) were delivered per session in 6 patiens with medically refractory VT. Two of the 6 patients had no recurrence of VT even without antiarrhythmic therapy and the remaining 4 patients had no recurrence with the same regimen that was ineffective before ablation during a follow-up period of 11.3±2.3 (range 8 to 14) months. The perforation of the right ventricular wall occurred immediately after ablation in one patient whose shock was delivered in the hard touch condition, but the patient had a good clinical outcome. In conclusion, catheter ablation for VT was effective and safe when it was performed in the soft touch condition.

抄録全体を表示