[Drug therapy of ventricular arrhythmia].
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Anti-Arrhythmia Agents↗
Biomedical subjects
K Hashiba
Publications and source records attributed to K Hashiba.
Effects of standing on the induction of paroxysmal supraventricular tachycardia.
To evaluate the effects of standing on induction of paroxysmal supraventricular tachycardia, electrophysiologic studies were performed in both the supine and standing positions in 22 patients with atrioventricular (AV) reciprocating tachycardia and in 11 with AV node reentrant tachycardia. AV reciprocating tachycardia was induced in 9 of the 22 patients with AV reciprocating tachycardia when they were in the supine position and in 17 when standing. The effective refractory period of the AV node markedly shortened, from 275 +/- 72 to 203 +/- 30 ms (n = 16, p less than 0.005) after standing. The effective refractory period of the accessory pathway shortened slightly, from 293 +/- 75 to 278 +/- 77 ms (n = 8, p less than 0.005), after standing. AV node reentrant tachycardia was induced in 3 of the 11 patients with AV node reentrant tachycardia when they were in the supine position and in 6 when standing. The effective refractory periods of the slow pathway and fast pathway shortened markedly, from 293 +/- 72 to 216 +/- 40 ms (n = 6, p less than 0.025) and from 416 +/- 85 to 277 +/- 50 ms (n = 10, p less than 0.005), respectively, after standing. Plasma norepinephrine levels increased during standing both in patients with AV reciprocating and in those with AV node reentrant tachycardia (n = 11, p less than 0.005, n = 8, p less than 0.005, respectively). In conclusion, standing, which is associated with increased sympathetic tone, changed the electrophysiologic properties of the reentrant circuits, facilitating induction of AV reciprocating tachycardia and AV node reentrant tachycardia.
Blood Pressure↗
Prolonged and fractionated right atrial electrograms during sinus rhythm in patients with paroxysmal atrial fibrillation and sick sinus node syndrome.
Intraatrial catheter mapping of the right atrium was performed during sinus rhythm in 92 patients: Group I = 43 control patients without paroxysmal atrial fibrillation or sick sinus node syndrome; Group II = 31 patients with paroxysmal atrial fibrillation but without sick sinus node syndrome; and Group III = 18 patients with both paroxysmal atrial fibrillation and sick sinus node syndrome. Atrial electrograms were recorded at 12 sites in the right atrium. The duration and number of fragmented deflections of the atrial electrograms were quantitatively measured. The mean duration and number of fragmented deflections of the 516 atrial electrograms in Group I were 74 +/- 11 ms and 3.9 +/- 1.3, respectively. The criteria for an abnormal atrial electrogram were defined as a duration of greater than or equal to 100 ms or eight or more fragmented deflections, or both. Abnormal atrial electrograms were observed in 10 patients (23.3%) in Group I, 21 patients (67.7%) in Group II and 15 patients (83.3%) in Group III (Group II versus Group I, p less than 0.001; Group III versus Group I, p less than 0.001). The mean number of abnormal electrograms per patient with an abnormal electrogram was 1.3 +/- 0.7 in Group I, 2.5 +/- 1.9 in Group II and 3.5 +/- 2.5 in Group III (Group I versus Group II, p less than 0.01; Group II versus Group III, p less than 0.05). A prolonged and fractionated atrial electrogram characteristic of paroxysmal atrial fibrillation can be closely related to the vulnerability of the atrial muscle.(ABSTRACT TRUNCATED AT 250 WORDS)
Aged↗
Arrhythmogenic properties of the ventricular myocardium in cardiomyopathic Syrian hamster, BIO 14.6 strain.
STUDY OBJECTIVE: Incidence of spontaneous cardiac arrhythmias and inducibility of ventricular arrhythmias in the cardiomyopathic hamster, BIO 14.6 strain, were examined. DESIGN: A 3 min electrocardiogram (ECG) was recorded weekly to 50 weeks of age. Programmed ventricular stimulation was then performed with single and double ventricular premature stimuli during both sinus rhythm and ventricular pacing, and with brief bursts of ventricular pacing to induce ventricular arrhythmias. EXPERIMENTAL MATERIAL: 19 male cardiomyopathic and 10 age matched normal hamsters from 16 to 50 weeks were used for recording the 3 min ECG; 11 cardiomyopathic and 10 normal hamsters aged 50 to 55 weeks were used for the induction of ventricular arrhythmias. MEASUREMENTS AND MAIN RESULTS: Spontaneous and sporadic ventricular premature contractions were documented in 8.3% of 218 ECGs from the cardiomyopathic hamsters between the ages of 30 and 46 weeks, whereas no ventricular arrhythmia was recorded in normal hamsters throughout the entire follow up period. Non-sustained ventricular tachycardia (NSVT) was induced in 7/11 cardiomyopathic hamsters by single ventricular premature stimulus. Either NSVT or ventricular fibrillation was induced in all cardiomyopathic hamsters with a significantly prolonged intraventricular conduction delay and refractory period. In contrast, neither NSVT nor ventricular fibrillation was induced in normal hamsters. CONCLUSION: This study provides the first evidence of the high arrhythmogenicity of the ventricles in cardiomyopathic hamsters.
Animals↗
Influence of sympathetic nerve activity on ventricular arrhythmogenicity in the dog with chronic hypokalemia.
To examine the influence of sympathetic nerve activity on ventricular arrhythmogenicity in the dog with chronic hypokalemia, an electrophysiologic study was performed before and after bilateral stellectomy (BS) in 10 dogs with chronic hypokalemia (2.8 +/- 0.1 mEq/L), which was created by feeding a low-potassium diet and by administering furosemide over a four-week period, and the results were compared with those obtained from 10 dogs with normokalemia (4.7 +/- 0.3 mEq/L) from being fed an ordinary diet over a four-week period. Before BS the incidence of electrically induced ventricular arrhythmias was higher in the hypokalemic than in the normokalemic dogs. After BS it was decreased considerably in the hypokalemic but not in the normokalemic dogs. Heterogeneity of effective refractory period (delta ERP), which was determined as the difference between the longest and shortest effective refractory periods in three sites of the right and left ventricles, was greater in the hypokalemic than in the normokalemic dogs before BS. The delta ERP decreased slightly in the two groups both before and after BS. There was, however, no significant difference in delta ERP in the two groups both before and after BS. Ventricular fibrillation threshold (VFT) was significantly lower in the hypokalemic dogs than in the normokalemic dogs before BS (p less than 0.005). VFT was elevated in the two groups after BS. Percent increase in VFT after BS was significantly greater in the hypokalemic than in the normokalemic dogs. In conclusion, sympathetic nerve activity may play an important role in the increase in ventricular arrhythmogenicity in the presence of chronic hypokalemia.
Animals↗
Changes in sodium-22 turnover and total body potassium in two-kidney, one-clip renovascular hypertension.
Changes in sodium-22 turnover and total body potassium (TBK) were studied during acute (within 2 weeks after clipping) and chronic (12-14 weeks after clipping) phases in two-kidney, one-clip (2k, 1c) hypertensive rabbits by using a whole body counter. Sodium-22 injected intravenously was eliminated more rapidly in hypertensive rabbits than in controls. The biological half-life (BHL) of sodium-22 was shorter in hypertensive rabbits during both acute (p less than 0.05) and chronic phases (p less than 0.001). A significant negative correlation was obtained between the BHL of sodium-22 and blood pressure (r = -0.588, p less than 0.05) in hypertensive rabbits. TBK decreased significantly at the chronic phase in hypertensive rabbits (p less than 0.05), while TBK showed no significant change in controls. Serum sodium and potassium did not change during the observation period. Increased plasma aldosterone concentration was observed during the acute phase in hypertensive rabbits. These results suggested that sodium retention was not a major factor in the acute and chronic phases of 2k, 1c hypertension in rabbits and that pressure natriuresis could explain, at least in part, the lack of sodium retention. Furthermore, there appears to be a derangement in the intracellular potassium metabolism which may be associated with the maintenance rather than the development of hypertension.
Aldosterone↗
Conduction properties of the antegrade fast and slow AV nodal pathways associated with AV nodal reentrant tachycardia.
To elucidate differences in conduction properties among the normal atrioventricular (AV) node and the antegrade fast and slow dual AV nodal pathways (DAVNPW), AV nodal conduction curves were analyzed quantitatively in 38 patients. Eighteen patients had antegrade DAVNPW with AV nodal reentrant tachycardia (AVNRT) (dual pathways group) and the remaining 20 had smooth AV nodal conduction curves, without evidence of AV nodal dysfunction (control group). The effective refractory period (ERP) of the antegrade fast pathway was longer than that of the normal AV node (at both basic cycle lengths of 700 and 500 msec, p less than 0.01). Although the atrial premature beats were delayed by a longer ERP in the fast pathway, there was no significant difference in the degree of prolongation of AV nodal conduction time related to shortening of the coupling interval (i.e., ratio of A2H2 increment to A1A2 decrement) between these two pathways. On the other hand, the ERP of the antegrade slow pathway was similar to that of the normal AV node. The degree of prolongation of AV nodal conduction time (relative to the shortening of the coupling interval) was greater in the antegrade slow pathway than in the normal AV node. In conclusion, these findings suggest that in DAVNPW with AVNRT: (1) the antegrade fast pathway is similar to the AV node and its conduction properties are unlikely to be better than those of the normal AV node and (2) the antegrade slow pathway has quantitatively poorer conduction properties than the normal AV node, since it has a greater degree of decremental conduction.
Adolescent↗
Effects of sympathetic and parasympathetic stimulation on the induction of atrial flutter in dogs with aseptic pericarditis.
To study the effects of sympathetic stimulation (SS) and vagal stimulation (VS) on the induction of atrial flutter (AF) and its cycle length, aseptic pericarditis was produced surgically in 17 adult mongrel dogs. Programmed atrial stimulation was used to induce AF and to determine the effective refractory periods (ERP) and maximum conduction delay (maxCD) of the atrium. These tests were performed before and during stimulation of the right cervical vagus nerve and the right stellate ganglion. Results showed: (1) AF could be induced in animals with short ERP and large maxCD before SS; (2) ERP was significantly shortened, maxCD was significantly increased by VS; (3) During SS, ERP was slightly shortened, but there were no changes in maxCD and the induction rate of AF; (4) The cycle length of AF was shortened by SS, however, the cycle length of AF was shortened more notably by VS than by SS. From these findings, a shortening of the ERP and an increase in maxCD appear to be related to an increased AF induction rate by VS.
Animals↗
[The relationship between the aortic pulse wave velocity and osteoporosis in elderly women].
The relationship between arteriosclerosis and osteoporosis (OP) was assessed in 20 elderly women. The aortic pulse wave velocity (PWV) was used as the index of arteriosclerosis and bone mineral content (BM) of the vertebral body, which was measured by quantitative computed tomography, was used as an index of OP. PWV and BM showed a significant correlation with aging (PWV and age: r = 0.466, p less than 0.05, BM and age: r = -0.487, p less than 0.05). In the group in which the serum alkaline phosphatase (ALP) was higher than 180 IU/l (n = 11), there was a significant inverse correlation between PWV and BM (r = -0.728, p less than 0.02). On the other hand, there was no correlation between PWV and BM in the group in which ALP was lower than 180 IU/l (n = 9). These results suggest that in cases with OP and high levels of ALP, calcium (Ca) seems to be released from the bone system and transferred to the wall of the aorta. The mechanism and pathogenesis of this Ca transference is unknown and should be investigated.
Aged↗
Effect of the adrenal inhibitor trilostane on the morphology of the adrenocortical cells of Dahl salt-sensitive and Dahl salt-resistant rats.
The effects of trilostane on the adrenal cortex of Dahl salt-sensitive (DS) and Dahl salt-resistant (DR) rats were investigated morphometrically, histochemically, ultrastructurally and biochemically. The statistical analysis indicated that trilostane induced a significant increase in the adrenal weight and the surface area of cells and nuclei in the zona fasciculata (ZF) of the adrenal cortex of DS and DR rats (P less than O.OI). DS rats treated with trilostane revealed marked accumulation of large amounts of lipid droplets and a decrease in the activity of 3 beta-hydroxysteroid dehydrogenase (3 beta-HSD) in the ZF. Ultrastructurally, the mitochondria of the ZF in DS rats treated with trilostane revealed swelling of matrix with a loss of cristae and occasional interruption of the membranes of mitochondria. Some of them had a continuity with lipid vacuoles or SER, presenting a characteristic 'feather'-like appearance. Other characteristic findings in DS rats treated with trilostane were a marked villous proliferation of plasma membranes with numerous dense bodies, occasional coated pits, and pinocytic vesicles in the outer portion of the ZF. In DS and DR rats the plasma level of ACTH increased, and corticosterone decreased significantly (P less than O.OI) after treatment with trilostane. These morphological alterations were considered to be an expression of the inhibitory effects of trilostane on the adrenal steroidogenesis in DS and DR rats, more especially in DS rats. Simultaneously there were confirmed morphological alterations in the cells of the ZF, reflecting the feedback stimulation of endogenous ACTH. The cells of the ZF of DS rats were more responsive to suppression by trilostane than those of DR rats.
3-Hydroxysteroid Dehydrogenases↗
[Non-specific intraventricular conduction disturbance and aberrant ventricular conduction].
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Adrenergic beta-Antagonists↗
Relationship between blood pressure and left ventricular mass in male patients with essential hypertension.
We performed retrospective study of the relationship between the severity and duration of hypertension and echocardiographically-detected left ventricular hypertrophy (echo-LVH) in patients with untreated essential hypertension. The subjects consisted of 92 untreated essential hypertensives who were observed for more than 5 years from the onset of diastolic hypertension (greater than or equal to 95 mmHg), and whose left ventricular (LV) mass index was measured at the end of the observation period. On the basis of the frequency of diastolic hypertension during the observation period, the population was categorized in 3 groups. In Group I (32 cases), diastolic hypertension was observed in more than 80% of blood pressures obtained throughout the entire observation period. In Group II (38 cases), diastolic hypertension was observed in 33 to 80% of the observation period. In Group III (22 cases), diastolic hypertension was observed in less than 33% of the observation period. The average diastolic blood pressure during the entire observation period in each group were 101.0, 96.0, and 90.7 mmHg in groups I, II, and III, respectively. The LV mass index was significantly higher in groups I (114.6 g/m2) and II (105.3 g/m2) than in group III (90.7 g/m2) (p less than 0.01). The prevalence of echo-LVH (more than 121 g/m2) was 34.4%, 18.4%, and 4.8% in groups I, II, and III, respectively. The average diastolic blood pressure in patients with echo-LVH (99.3 +/- 5.1 mmHg) was significantly higher than in patients without echo-LVH (95.7 +/- 4.7 mmHg). We concluded that the degree and duration of diastolic pressure elevation are closely correlated to the LV mass index.
Blood Pressure↗
The influence of glycosylation on the fate of renin expressed in Xenopus oocytes.
It has been recently reported that, in Xenopus oocytes injected with the mRNA for human renin, this secretory renal glycoprotein acquires phosphomannosyl residues on its asparagine-linked oligosaccharide chains, remains intracellular and undergoes a proteolytic cleavage which removes the prosegment. To understand the influence of glycosylation on the fate of renin in Xenopus oocytes and whether it is specific for human renin, we have expressed human renin and mouse Ren1 renin, which are glycosylated at two and three selected asparagine residues, respectively, and mouse Ren2 renin, which is not glycosylated, in Xenopus oocytes. The majority of human and Ren1 renins remained intracellular and underwent proteolytic cleavage, whereas mouse Ren2 renin was secreted efficiently. When human and Ren1 renins were expressed in oocytes treated with tunicamycin, both were secreted efficiently. A mutant of human renin, which had amino-acid substitutions at both glycosylation sites, was also secreted efficiently, whereas that mutated at one of the two sites was not. These results indicate that the majority of all of the glycosylated renin molecules remain intracellular and undergo proteolytic cleavage, probably due to the acquisition of phosphomannosyl residues, and the human renin remains intracellular if it is only glycosylated at one of the two sites.
Amino Acid Sequence↗
A processing enzyme for prorenin in mouse submandibular gland. Purification and characterization.
Renin is produced from an inactive precursor, prorenin, through proteolytic cleavage at paired basic amino acid residues. In this study, an enzyme which specifically cleaves mouse Ren 2 prorenin at the paired basic residues has been purified from mouse submandibular gland by CM-Toyopearl chromatography, antipain-Sepharose chromatography, and isoelectric focusing. This enzyme, named prorenin converting enzyme, consists of two polypeptide chains of 17 and 10 kDa. The enzyme has an isoelectric point of 9.5-9.8, and its pH optimum is between 7.5 and 8.5. It specifically cleaves the peptide bond on the carboxyl side of the Arg at the Lys-Arg pair of mouse Ren 2 prorenin to yield mature renin but does not cleave mouse Ren 1 and human prorenins. Studies on the effects of inhibitors indicate that this enzyme is a serine protease that differs from the enzymes processing other prohormones at paired basic amino acid residues.
Amino Acid Sequence↗
Suppression of exercise-induced ventricular arrhythmias by propranolol and diltiazem in a woman without organic heart disease--a case report.
A thirty-five-year-old woman without organic heart disease who has exercise-induced ventricular arrhythmias suppressed by propranolol and diltiazem is reported. Treadmill exercise provoked reproducibly nonsustained ventricular tachycardia (NSVT) and salvos of ventricular premature contraction (VPC). QRS morphology of these ventricular arrhythmias showed left bundle branch block pattern and right axis deviation. Oral propranolol (20 mg) and diltiazem (90 mg) prevented exercise provocation of NSVT and VPC. However, oral mexiletine (200 mg) and procainamide (500 mg) could not prevent exercise provocation of these ventricular arrhythmias. No ventricular arrhythmias could be induced by any form of ventricular extrastimulations. Right ventricular pacing at a rate of 210 beats/minute provoked NSVT of which the QRS morphology was similar to that of exercise-induced NSVT. Triggered activity may be a possible electrophysiologic mechanism for exercise-induced ventricular arrhythmias in this patient, although other mechanisms such as reentry and enhanced automaticity could not be completely excluded.
Adult↗
Prediction of a fatal atrial fibrillation in patients with asymptomatic Wolff-Parkinson-White pattern.
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 less than 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.(ABSTRACT TRUNCATED AT 250 WORDS)
Atrial Fibrillation↗
Long-term observation of cardiac function in Duchenne's muscular dystrophy. Evaluation using systolic time intervals and echocardiography.
Cardiac involvement is common in patients with Duchenne type muscular dystrophy (DMD). However, published reports of long-term follow-up studies in the same patients are very rare. The purpose of this study was to clarify the natural course of cardiac dysfunction in DMD, and to analyze the relationship between the deterioration of cardiac function and skeletal muscular function. The cardiac function was serially evaluated for 2-12 years in 34 patients with DMD. The systolic time intervals and echocardiography were used for evaluating the cardiac function. The PEP/ET (pre-ejection period/ejection time) of systolic time intervals significantly deteriorated in 9-12 years (p less than 0.001). The maximal systolic and diastolic endocardial velocity (MSEV and MDEV) and the D/S ratio of echocardiography significantly deteriorated in 5 years (p less than 0.001). The D/S ratio is the ratio of the mean systolic velocity and the mean diastolic velocity of the left ventricular posterior wall. In almost half the patients, the deterioration of these parameters was correlated with that of Swinyard's stage. The Swinyard's functional ability stage demonstrates the grade of the skeletal muscular dysfunction. However, there was no correlation between the deterioration of cardiac function and Swinyard's stage in the other half of the patients. Correlation coefficient in the whole group was 0.32 (p = n.s.) between the PEP/ET and Swinyard's stage, and was -0.15 (p = n.s.) between the D/S ratio and Swinyard's stage. Although the mean left ventricular ejection fraction calculated using echocardiography was slightly decreased for 5 years, no significant change was detected in the whole group. One patient had progressive deterioration of left ventricular function despite mild skeletal muscular dysfunction, and died from congestive heart failure. The cardiac dysfunction was predominant. We named it 'cardiac type' DMD. Since deterioration of cardiac function was not always correlated with deterioration of skeletal muscular function (Swinyard's stage), cardiac function must be carefully monitored in patients with DMD.
Adolescent↗
The relationship between 24 hour total heart beats or ventricular arrhythmias and cardiopulmonary function in patients with Duchenne's muscular dystrophy.
To evaluate the relationship of 24 hour total heart beats (THB) or ventricular arrhythmias and cardiopulmonary function, 29 patients with Duchenne's muscular dystrophy (DMD) were studied using Holter electrocardiographic and echocardiographic recordings. The THB were 144,428 +/- 12,237 beats per 24 hours in the child group (8 to 15 years, n = 12) and 136,355 +/- 19,991 beats per 24 hours in the adult group (16 to 25 years, n = 17). The THB in the adult group significantly correlated well with % VC (r = -0.74), PaCO2 (r = 0.67), PaO2 (r = -0.59) and the respiration rate (r = 0.71), but not in the child group. In both groups, the echocardiographic parameters of the left ventricular size and function (left ventricular dimension, ejection fraction and D/S ratio) did not significantly correlate with the THB. Premature ventricular contractions (PVCs) were observed in 14 of the 29 patients (48.3%), and high risk PVCs (Lown's grade 3-4b) were observed in 11 of these 14 patients (78.6%). Echocardiographic parameters of the left ventricular function in the high risk PVC group were significantly deteriorated as compared with the low risk PVC group (Lown's grade 0-2) (p less than 0.02-p less than 0.001). We conclude that the THB in the adult group was mainly related to depressed pulmonary function, and the severity of the PVCs in both the adult and child groups was mainly related to the degree of left ventricular dysfunction.
Adolescent↗