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Biomedical subjects

D Y Hu

Publications and source records attributed to D Y Hu.

10 recordsLinked to original sources
PubMed1992

Prediction of life-threatening arrhythmia in patients after myocardial infarction by late potentials, ejection fraction and Holter monitoring.

In order to compare the prognostic significance of late potentials (LPs) on signal-averaged electrocardiogram (SA-ECG), left ventricular ejection fraction (EF) and 24-hour Holter monitoring (HM) following myocardial infarction, a prospective study on 60 patients (age 61.7 +/- 8.02 years old) just after acute myocardial infarction (AMI) was done. LPs, EF and HM were performed in all patients. Coronary arteriography had been done in 25 patients. The results showed that LPs were associated with a slightly higher incidence of life-threatening arrhythmia (34.8%) than HM (28.6%) and EF (25%). During the follow-up period (10 +/- 6 months), 9 patients had serious ventricular arrhythmic events, among whom 3 had sudden death due to ventricular fibrillation. The event rate in patients with abnormal LPs was higher than in patients with normal LPs (p = 0.01, odds ratio = 19.2). The study showed that there was no correlation between abnormal LPs and sex, age, number of narrowed coronary arteries, ventricular aneurysm, location of myocardial infarction, or EF alone. But there was a correlation between abnormal LPs and high grade ventricular ectopic activity detected by HM (r = 0.62899, p = 0.024). In addition, the combination of abnormal values of LPs, EF and HM could predict sustained ventricular tachycardia or sudden death in the first year after myocardial infarction with very high sensitivity (100%) as well as high specificity (p = 0.0009, odds ratio = 19).

Adult↗
PubMed1992

[Clinical application of radiofrequency ablation].

UNLABELLED: I. Radiofrequency ablation of atrioventricular accessory pathway in patients with WPW syndrome: Seventeen accessory pathways in 15 patients with Wolff-Parkinson-White syndrome (WPW) were ablated with radiofrequency current. There were 15 accessory pathways located on the left side of the heart (12 left free wall, 1 posterioseptal, 1 posteriolateral and 1 midseptal) and 2 pathways on the right side (1 right free wall, 1 anterioseptal). 16 accessory pathways (94.1%) in 14 patients were permanently abolished. Plasma CK-Mb, SGOT and LDH increased moderately in 7 cases (46.7%) and decreased to normal level in 3-4 days. CONCLUSION: catheter ablation of accessory pathways with radiofrequency current is a safe and effective therapeutic method for patients with refractory tachycardias mediated by these pathways. II. Radiofrequency ablation of slow pathways to cure AV nodal reentrant tachycardia: Radiofrequency energy was used to selectively ablate the slow pathways in 8 patients with atrioventricular nodal reentrant tachycardia. The slow pathways in all 8 cases were ablated successfully and no episodes of tachycardia could be induced. The A-H, H-V interval and P-R interval of ECG did not change significantly. The Wenckebach points of atrioventricular node remained unchanged. The effective refractory periods of the fast pathways were shortened in 3 and prolonged in 5 cases after the procedure. There were no severe complications. No tachycardia recurred during the follow-up period between 2 weeks and 7 months.

Adolescent↗
PubMed1992

Cardiovascular mechanisms of thyrotropin-releasing hormone against experimental hemorrhagic shock.

Thyrotropin-releasing hormone (TRH) improved mean arterial pressure (MAP) and myocardial contractility (dp/dtmax, -dp/dtmax, Vpm, and Vmax) and increased plasma epinephrine levels significantly at 10 min after TRH treatment in rabbits following shock, but the effects of TRH on MAP and myocardial contractility disappeared in reserpinized rabbits (4 mg/kg, 24 hr pre-treatment, iv). TRH had no effect on myocardial contractility and MAP at 20 and 30 min post-treatment in rabbits pre-treated with the beta adrenergic blocker propranolol (1 mg/kg, 1 hr before TRH treatment, iv), but the alpha adrenergic blocker phenoxybenzamine did not affect these responses to TRH. Experiments in vitro show that although TRH (10(-3) to 10(-8) M) had no direct effects on the isolated heart, left atrium, and aortic strip, it did potentiate the inotropic effects of isoprenaline and dopamine on the left atrium. These results suggest that the antishock effects of TRH are related to adrenergic systems, perhaps acting on the sympathomedullary system to secrete epinephrine and sensitize the beta receptors, but not alpha receptors. Thus, TRH improves cardiac contractility, cardiac output, and hemodynamics during hemorrhagic shock. The sensitization of the beta adrenergic and dopamine receptors may play an important role in the direct peripheral cardiovascular mechanism of TRH effects.

Animals↗
PubMed1991

[The prognostic significance and correlation of ventricular late potentials with programmed electrical stimulation in patients after myocardial infarction].

Seventeen patients (pts) after myocardial infarction (MI) were studied with signal-averaged electrocardiograph and cardiac programmed electrical stimulation (PES). In 7 pts with late potentials (LPs), sustained ventricular tachycardia (SVT) was induced in 6 cases (6/7, 85.7%); while it was induced only in 3 cases the 10 pts without LPs (3/10, 30%). Both have significant difference (P less than 0.01). During following observation, pts with LPs and SVT induced 5 of the 6 appeared clinical SVT or ventricular fibrillation (VF) repetitiously, and 1 died from sudden cardiac death. They also have significant difference (P less than 0.001) with pts without LPs and SVT not induced. These results suggests that LPs is a significant index for predicting future events and its combination with PES is helpful to screen high-risk pts after MI.

Adult↗
PubMed1990

Long-term follow-up in patients with incessant ventricular tachycardia.

Seventeen patients with coronary artery disease, idiopathic dilated cardiomyopathy or no organic heart disease who presented with incessant ventricular tachycardia (VT) were studied and followed for a mean period of 51 +/- 35 months. In these patients the incessant VT included greater than or equal to 3 episodes of sustained VT at a rate of greater than or equal to 120 beats/min and frequent episodes of nonsustained VT over a 24-hour period. No patient had electrolyte disorder, prolonged QT interval, drug-induced arrhythmia or myocardial infarction less than 2 weeks old. Six patients died within 27 months of follow-up; 4 from sudden death and 2 from acute myocardial infarction. Three of the 11 surviving patients had remission of their VT within 1 week after the diagnosis of incessant VT. In 3 other patients in whom antiarrhythmic drugs were discontinued during follow-up because of adverse effects of the drugs or other medical reasons, 2 were found in remission. In the remaining 5 alive patients, deliberate attempts were made to discontinue the antiarrhythmic drugs; 4 of these patients were found in remission when the drugs were discontinued. Thus, 9 of these patients (53%) with incessant VT had remission over a mean follow-up of 55 +/- 34 months after discontinuation of the antiarrhythmic drugs. The probability of remission in patients surviving incessant VT warrants trials of discontinuation of antiarrhythmic drugs in these patients.

Adolescent↗
PubMed1990

Action of thyrotropin-releasing hormone in experimental hemorrhagic shock--cardiovascular mechanism.

Thyrotropin-releasing hormone (TRH) could improve mean arterial pressure (MAP), myocardial contractile parameters (+/- dp/dtmax, Vpm and Vmax) and increase plasma epinephrine level significantly at 10 min after TRH administration in hemorrhagic shock rabbits, but the action of TRH on MAP and the myocardial contractility did not appear in rabbits pre-treated with reserpine (4 mg/kg, 24 h pre-treatment, i.v.). TRH had no effects on myocardial contractility and MAP at 20 and 30 min after administration to rabbits pre-treated with beta-adrenergic blocker propranolol (1 mg/kg, 1 h before TRH injection i.v.), but it did exert effects on these parameters in rabbits pre-treated with alpha-adrenergic blocker phenoxybenzamine. Experiments in vitro showed that, although TRH (10(-4) M/L) had no direct effect on heart, left atrium and aortic strip, it did potentiate the inotropic effects of isoprenaline and dopamine on the left atrium. These results suggested that antishock effect of TRH is related to adrenergic system. TRH stimulates sympathomedullary system to secrete epinephrine and sensitize the beta-receptors, but not alpha-receptors. Thus, TRH improves cardiac contractility, cardiac output and hemodynamics during hemorrhagic shock. The sensitization of the beta- and dopamine receptors played an important role in producing direct peripheral actions of TRH.

Adrenergic beta-Antagonists↗
PubMed1989

Cryothermal mapping of the sinus node in dogs: a simple method of localising dominant and latent pacemakers.

To investigate the potential use of cryothermal mapping to localise the sites of the dominant and latent pacemakers of the sinus node, we compared the results of cryothermal and electrical mapping of the sinus node in 16 dogs. In all dogs, cooling (-5 to +5 degrees C) of a localised epicardial area of about 3 X 3 mm2 close to the sulcus terminalis (area 1) resulted in a decrease in heart rate and a change in the P wave configuration. Cooling of an additional area of up to 15 X 3 mm2 (area 2) while cooling of area 1 was maintained resulted in a further decrease in heart rate and a further change in P wave configuration until junctional rhythm occurred. In all dogs areas 1 and 2 could be identified within 5 min. The heart rate and P wave configuration returned to control following cooling suggesting no adverse effect of cooling on the sinus node in this temperature range. In dogs with sufficiently slow heart rates, recording from area 1 showed diastolic and upstroke slopes followed by primary negativity, indicating that area 1 was the area of the dominant pacemaker. Recording from area 2 showed only diastolic slopes indicating that area 2 was the area of the latent pacemaker. Compared to electrical mapping for identifying diastolic slope, upstroke slope and primary negativity or earliest atrial activation, cryothermal mapping is a simple, quick and safe procedure for localisation of the sinus pacemakers. Unlike recording of sinus nodal electrograms, cryothermal mapping can be performed in the presence of rapid heart rates.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗