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Biomedical subjects

F T Chiang

Publications and source records attributed to F T Chiang.

At least 55 records · Page 3Linked to original sources
PubMed1996

Age- and gender-dependent association of the angiotensin-converting enzyme gene with essential hypertension in a Chinese population.

A case-control study was carried out on 272 Chinese subjects over 40 years of age, including 157 hypertensives and 115 normotensives, to examine the association between angiotensin-converting enzyme (ACE) gene insertion/deletion (I/D) polymorphism and blood pressure (BP) status. The I/D polymorphism of the ACE gene was identified by polymerase chain reaction. As a whole group, the difference of allele frequencies between normotensives and hypertensives was statistically significant (chi 2 = 4.46, P = 0.03; D/I odds = 1.46), while there was no difference in the genotype distribution (chi 2 = 3.95, P = 0.13). In a subgroup with elderly hypertension (age > 65), the frequencies of D-allele and DD genotype significantly increased (chi 2 = 4.43, P = 0.03 and chi 2 = 4.03, P = 0.08, respectively; D/I odds = 2.28). The association and relative risk increased further in the male gender (chi 2 = 6.65, P = 0.01 and chi 2 = 7.51, P = 0.02 respectively; D/I odds = 4.57 and DD/II odds = 12.00 respectively). The D-allele increased with age in the hypertensives, while the I-allele increased with age in normotensives. Thus, we conclude that the deletion polymorphism of the ACE gene is significantly associated with male elderly hypertension, at least in this Chinese population. This observation, if proved in a larger population, may have some implications for the prevention and treatment strategy for elderly hypertension.

Adult↗
PubMed1995

Influence of isolated diastolic hypertension identified by ambulatory blood pressure on target organ damage.

Clinical decisions and controlled studies in regard to hypertension have long emphasized the casual diastolic blood pressure (DBP). The influence of superimposition of high systolic blood pressure (SBP) on the target organ damage has been less studied. To assess the role of isolated diastolic hypertension without interference of superimposition of systolic hypertension, 171 subjects with normal blood pressure, isolated diastolic hypertension (SBP < 140 and DBP > or = 90 mmHg) isolated systolic hypertension (SBP > or = 140 and DBP < 90 mmHg) or combined hypertension (SBP > or = 140 and DBP > or = 90 mmHg) determined by mean 24-h ambulatory blood pressure were compared in relation to target organ damage including ECG abnormality related to hypertension, cardiac enlargement by chest X-ray, proteinuria and retinopathy. The incidence of target organ damage was lower in subjects with normal BP than in the other three groups. The incidence of target organ damage was almost significantly higher in patients with isolated systolic hypertension than in those with isolated diastolic hypertension. No significant difference in the incidence of complications existed between patients with isolated systolic and combined hypertension. These findings demonstrate that the severity of hypertensive complications is more closely related to mean ambulatory SBP than mean ambulatory DBP. The level of systolic BP is important for predicting the severity of target organ damage in patients with high diastolic BP, because there is a significant difference in the incidence of target organ damage between isolated diastolic hypertension and combined hypertension.

Arrhythmias, Cardiac↗
PubMed1995

Vectorcardiography in experimental myocardial infarction. Serial changes and correlation between QRS loop change and the infarction size.

The objectives of this study were to examine the serial vectorcardiographic changes following acute myocardial infarct and to assess the relationship between QRS loop changes and infarct size. Fifty adult male Long-Evans rats of 250-350 gm body weight were used to study experimental acute myocardial infarction induced by coronary artery ligation. Vectorcardiograms (VCG) of the Frank lead system were recorded before, and 1 day and 7 days after operation. Animals were sacrificed on the 7th day for histological quantitation of infarct area ratios. We found that (1) before operation, rats have ST elevation, probably due to early repolarization. (2) After coronary artery ligation, ECG showed characteristic dome-shaped ST elevation at 1 hr after ligation which returned to normal during the first day. Abnormal Q waves appeared thereafter. (3) After ligation, maximum QRS vector, ST vector and maximum T vector were reduced in magnitude the first day and recovered by the 7th day. The vectors tended to shift their direction to the right and to the posterior. QRS-T angle, however, widened as time went on. About half of the rats revealed changes in the inscription direction of the QRS loop and abnormal QRS morphology also appeared in about half of the ligated rats. (4) Those in whom abnormal QRS loop morphology and/or biting appeared had significantly larger infarct area ratios (p < 0.01). (5) Change in QRS loop inscription direction seemed not to be related to the infarct size. (6) In the LS plane, the difference in max QRS vector magnitude between the 1st and 7th days significantly correlated with the infarct area ratio (r = 0.533, p < 0.05). In the H plane, the change in the max QRS vector magnitude at the 7th day correlated with the infarct area ratio (r = -0.531, p < 0.05). In the F plane, changes in the direction of the max QRS vector were significantly correlated to the infarct area ratio both on the first (r = 0.431, p < 0.05) and 7th days (r = 0.531, p < 0.05). It is concluded that the VCG, like the ECG, had evolutional changes in AMI and that the QRS loop seen on vectorcardiography has only a slight correlation with the histological myocardial infarct size.

Animals↗
PubMed1995

Anaerobic metabolism in patients undergoing intra-aortic balloon counterpulsation for cardiogenic shock.

To find the best predictors of outcome for patients undergoing intra-aortic balloon counterpulsation (IABP) for cardiogenic shock, we prospectively studied 30 consecutive patients by examining hemodynamic parameters and cardiac lactic acid extraction ratios before the procedure. 1 hour after and then every 6 hours for 3 days. Complete hemodynamic data were obtained from the recordings of Swan-Ganz catheterization. Blood samples were drawn from the peripheral artery, central vein, pulmonary artery wedge position (PAW) and right atrium (RA) to quantify lactic acid levels. The simplified lactic acid extraction ratio was defined as the concentration of lactic acid in RA--the concentration of lactic acid in PAW/the concentration of lactic acid in PAW. The traditional systemic lactic acid production ratio was defined as the concentration of lactic acid in the central vein--the concentration of lactic acid in the peripheral artery/the concentration of lactic acid in the peripheral artery. Of the 30 patients studied, 19 died of cardiogenic shock, (group 1), while the surviving 11 patients formed group 2. The lactic acid extraction ratios at each of the time periods after the procedure were all significantly different, while the differences in the systemic lactic acid production ratio and hemodynamic parameters, including the systemic arterial pressure, cardiac output, cardiac index and PAW pressure, became significant at varying times after IABP. In group 2, the lactic acid extraction ratios 1 hour after IABP and later were all significantly higher than at baseline. This trend was not seen in group 1.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Circadian variations of atrial natriuretic peptide in normal people and its relationship to arterial blood pressure, plasma renin activity and aldosterone level.

To investigate the circadian variations of plasma atrial natriuretic peptide (ANP) and its relationship to arterial blood pressure, plasma renin activity and aldosterone level, we determined 24-h blood pressure in 14 healthy volunteers. Plasma ANP concentration, renin activity and aldosterone levels were measured every 3 h by radioimmunoassay. We found no significant circadian variation of plasma ANP level (pg/ml) (daytime level, 62 +/- 24 vs. nighttime level, 57 +/- 19, P = 0.146) and plasma renin level (ng/ml/h) (1.32 +/- 0.78 vs. 1.15 +/- 0.57, P = 0.148), but there was diurnal change of blood pressure (mmHg) (systolic, 122 +/- 7 vs. 116 +/- 11, P < 0.001; diastolic, 80 +/- 11 vs. 72 +/- 11, P = 0.025) and plasma aldosterone level (pg/ml) (86 +/- 42 vs. 62 +/- 37, P < 0.001). The blood pressure and aldosterone levels reached maxima (11:00 h and 08:00 h, respectively) before that of ANP (17:00 h) and then decreased together until the nadir at 02:00 h. This might indicate that elevation of arterial blood pressure and plasma aldosterone level stimulate release of ANP under normal physiological conditions.

Adult↗
PubMed1994

Atrial natriuretic peptide is produced less in the intercaval sinus than in the pectinated right atrium.

To explain the lower atrial natriuretic peptide concentrations after total cavopulmonary connection than after the Fontan procedure, a prospective study was carried out in seven rats to count the specific granules of atrial natriuretic peptide by electronmicroscope. After fasting from water for 12 days, the quantity of specific granules in the right atrial appendage (pectinated part), intercaval sinus (smooth part), and superior vena cava were counted. The number of specific granules present in the pectinated part of right atrium was 97 +/- 19 in 20 cells, while in the intercaval sinus it was 23 +/- 19 (mean +/- SD). The difference was significant statistically (p < 0.0001). No granule was present in the superior vena cava. We conclude that the granularity of atrial natriuretic peptide is less in the intercaval sinus than the pectinated part of the right atrium.

Animals↗
PubMed1994

Characteristic abnormal findings of ambulatory blood pressure indicative of hypertensive target organ complications.

To study the correlation between ambulatory blood pressure and target organ complications of hypertension, ambulatory blood pressure monitoring was performed on 290 patients with mild to moderate essential hypertension before treatment. Their target organ complications of hypertension were assessed by ECG, chest X-ray, urinalysis and an eye-fundus examination. An average ambulatory diastolic blood pressure value greater than the casual diastolic blood pressure was found in 35% of subjects with ECG evidence of left ventricular hypertrophy (LVH) and 5.2% of subjects without (P < 0.001); in 36.5% of patients with chest roentgenographic evidence of LVH and 8.4% of patients without (P < 0.0001); in 38.5% of patients with proteinuria and 11% of patients without (P < 0.0001); and in 27.1% of subjects with retinopathy and 10.7% of subjects without (P < 0.01). A similar result was observed for the systolic blood pressure. A reversed circadian pattern of ambulatory diastolic blood pressure was observed in 32.5% of patients with ECG evidence of LVH and 12.9% without (P < 0.0001); in 28.8% of patients with chest roentgenographic evidence of LVH and 16% without (P < 0.05); in 26.9% of subjects with proteinuria and 17.4% without (P < 0.05); in 37.5% of patients with retinopathy and 14.5% without (P < 0.0001). A similar result was also demonstrated for ambulatory systolic blood pressure. There was a close relationship between the blood pressure load and hypertensive target organ complications in terms of LVH and proteinuria, and between significant nocturnal reduction of ambulatory systolic blood pressure and LVH.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Effect of EGb 761, a ginkgo biloba extract, on early arrhythmia induced by coronary occlusion and reperfusion in dogs.

EGb 761 is a preparation of Ginkgo biloba extract, which has complex biologic actions including free radical scavenging activity. To examine the anti-arrhythmic effect of EGb 761, a canine preparation of coronary artery occlusion-reperfusion was tested. Under intravenous anesthesia and open chest conditions, 32 dogs were subjected to 30 min of coronary occlusion, followed by reperfusion. Twelve received EGb 761 by intravenous injection, 1 mg/kg five minutes before coronary occlusion, followed by a continuous infusion of 0.1 mg/kg/min until five minutes after reperfusion. Immediately prior to reperfusion, an additional bolus dose of EGb 761 (1 mg/kg) was again injected (group A). The remaining 20 dogs received saline injection, and served as the control (group B). The electrocardiographic changes were recorded during the whole experimental course. The results showed that, during coronary occlusion, group A dogs had a lower count of ventricular premature beats than group B dogs. However, there was no difference in the incidence of ventricular tachycardia (VT) between the two groups. The duration of VT of the treated dogs was similar to that of the control dogs. The incidence of ventricular fibrillation (VF) was also similar. Upon reperfusion, the treated dogs were shown to be protected from VF. The duration of VT was also shorter in the treated group, although the incidence of VT was not different between the two groups. EGb 761 is effective in preventing early VF induced by coronary reperfusion while ineffective in protecting the ischemic VT and VF.

Animals↗
PubMed1993

Bidirectional shunt through a residual atrial septal defect after percutaneous transvenous mitral commissurotomy.

A residual atrial septal defect with bidirectional shunt was detected by transesophageal echocardiography in a 28-year-old man 3 years after percutaneous transluminal mitral commissurotomy (PTMC) with the antegrade transseptal technique. He had had severe mitral stenosis, pulmonary hypertension, and tricuspid regurgitation before the procedure. The result of PTMC was suboptimal, the pulmonary hypertension regressed only partially, and the tricuspid regurgitation remained severe. These factors contributed to the bidirectional shunt. A bidirectional shunt is known to be associated with systemic desaturation and a higher risk of paradoxical embolization and brain abscess. When PTMC is considered in patients with pulmonary hypertension and tricuspid regurgitation, a retrograde left ventricular approach with or without transseptal puncture can avoid the atrial septotomy, decrease the incidence of significant shunt, and should be a rational alternative.

Adult↗
PubMed1993

Body surface potential maps of ventricular depolarization in normal adults.

Body surface potential maps were obtained in 50 normal adults using the heart potential map system designed by Yamada. Group A (younger adult group) consisted of 30 persons whose ages ranged from 20 to 39 years. Group B (middle-aged group) included 20 persons whose ages ranged from 40 to 59 years. Although there were slight variations in the pattern of isopotential distribution among the subjects studied, a consistent pattern with a similar sequence was observed in both study groups. However, there were some parameters which significantly differed between groups A and B, including the earliest appearance time of the anterior negative potential (p < 0.05), the anterior potential minimum (p < 0.001), the posterior positive potential (p < 0.001), the midsternal minimum (p < 0.001), the largest potential minimum (p < 0.05), the largest potential maximum (p < 0.005), the "reversal" pattern (p < 0.001), the multipolar potential distribution in the upstroke (p < 0.001) and the amplitude of potential minimum in the periods 50 msec (p < 0.005) and 60 msec (p < 0.01) of ventricular depolarization. Accordingly, the data obtained regarding the time relationship between the bipolar and multipolar phases, the distribution and time course of the potential as well as the dynamic changes in potential voltage, particularly the age-related potential pattern will serve as a basis for further study of BSPM.

Adult↗
PubMed1993

Influence of age on ambulatory blood pressure in treated hypertensive patients with normal casual pressure.

To investigate the influence of age on ambulatory blood pressure monitoring (ABPM) in hypertensive patients whose controlled casual blood pressure was normal, we studied the ABPM in 225 patients, including 122 men and 103 women, aged from 45-74 years. They were classified into three groups: Group A included 93 patients aged 45 to 54 years; Group B included 99 patients, aged 55-64 years; and Group C included 33 patients, aged 65 years and over. The various ABPM data were analyzed and compared among the three groups. The following results were found. The blood pressure (BP) averages for the whole day were normal in all three groups. There was no difference in the systolic BP average among the three groups, but the diastolic BP average declined as age increased. The variability in the systolic BP measurements increased with age. The variability in diastolic BP did not seem to change as conspicuously with age, except for the group C patients who showed a larger variability at nighttime than the other two groups. There were 123 patients (54.7%) with evidence of diurnal change in BP, and the incidence of diurnal change in BP decreased with age. The frequency of abnormally high systolic BP was similar among the three groups, but the frequency of an abnormally high diastolic BP decreased significantly with age. As for the maximal BP levels recorded in the ABPM, group C patients had a higher maximal systolic BP than the other two groups. Therefore, age has a great influence on ABPM in controlled hypertensive patients with normal casual BP.

Aged↗
PubMed1993

Cardiac amyloidosis presenting as sick sinus syndrome and intractable heart failure: report of a case.

Cardiac amyloidosis, an uncommon disease, has been reported to manifest as congestive heart failure (CHF) and/or various arrhythmias. Herein, we report a case of CHF and sick sinus syndrome. The patient, a 66-year-old man, was admitted to the National Taiwan University Hospital because of dizzy spells and recurrent syncope. Electrocardiogram showed a sinoatrial block, first degree atrioventricular block, right bundle branch block and low-voltage Q wave, R wave and S wave (QRS) complex. Prolonged corrected sinus node recovery time was documented by an atrial pacing study. A permanent pacemaker was implanted for the patient's bradyarrhythmia, but he developed progressive heart failure. Echocardiography revealed a normal-sized ventricular chamber, concentric left ventricular hypertrophy with a "granular sparkling" appearance of the myocardium, and impaired diastolic and systolic function of the left ventricle. Despite aggressive treatment, the patient expired due to intractable heart failure. Postmortem needle aspiration revealed amyloidosis involving the heart, lung and skin. We conclude that cardiac amyloidosis should be considered in elderly patients with conduction disturbance and unexplained congestive heart failure.

Aged↗
PubMed1992

Characteristic abnormal features of body surface potential maps predictive of ventricular tachycardia following coronary artery occlusion in dogs.

In a search for features predictive of ventricular arrhythmias in myocardial ischemia, the body surface potential maps of 17 dogs with coronary artery occlusion were studied. Ventricular tachycardia occurred in 9 (53%) of the 17 dogs. Multiple distribution of the abnormal potential minimum was found in 6 (67%) of the 9 dogs with (group A) and none of the 8 dogs without ventricular tachycardia (group B). The difference was statistically significant (p less than 0.01). The abnormal "early reversal" phenomenon of potential distribution was observed in 6 (67%) of group A and 7 (88%) of group B. The difference was not statistically significant (p greater than 0.05). The area of abnormal negative potential was 28.0 +/- 8.5 cm2 for group A and 14.5 +/- 5.5 cm2 for group B (p less than 0.001). The abnormal negative potential lasted for 25.4 +/- 3.5 ms in group A and 10.1 +/- 5.1 ms in group B (p less than 0.001). The abnormally early appearance of potential minimum lasted for 24.2 +/- 5.1 ms in group A and 10.5 +/- 5.4 ms in group B (p less than 0.001). The data suggest that the distribution, area, and duration of the abnormal negative potential of the body surface potential map are useful in the prediction of ventricular tachycardia associated with coronary artery occlusion.

Animals↗
PubMed1992

Cardiac metastasis of hepatocellular carcinoma mimicking pericardial effusion on radionuclide angiocardiography.

A 51-year-old man presented with exertional dyspnea for two months. He had a history of hepatocellular carcinoma that was totally resected three years earlier. Radionuclide angiocardiography disclosed a large photopenic area separating the heart from the liver, and lung blood pools mimicking a large pericardial effusion. Echocardiography and magnetic resonance imaging of the heart, however, showed extensive tumor infiltration of the myocardium of both ventricles. Endomyocardial biopsy confirmed the diagnosis of metastatic hepatocellular carcinoma. There was no evidence of recurrent hepatoma in the liver.

Carcinoma, Hepatocellular↗
PubMed1992

Correlation between left ventricular systolic function and dipyridamole thallium SPECT redistribution patterns in coronary artery disease.

The dipyridamole thallium-201 single photon emission computed tomography (SPECT) and resting gated blood pool ventriculography were sequentially conducted in 31 consecutive patients with angiographically proven coronary artery disease. The functional significance of various thallium redistribution patterns was assessed. The patients with an entirely complete (CR) or partial (PR) redistribution pattern had a higher global left ventricular ejection fraction than those with combined PR and no redistribution (NR), while patients with an entirely CR pattern did not have a statistically better ejection fraction than those with PR. Furthermore, myocardial segments with normal perfusion (N) and those with CR or PR had a higher regional ejection fraction than those with NR in the infero-apical area and the septal area. The regional ejection fraction was statistically higher in patients with CR than in those with PR in the septal area and higher, though not statistically significant, in the infero-apical area. The functional difference between groups with N and CR was not significant. Thus, we conclude that the redistribution patterns of dipyridamole thallium SPECT are closely correlated with systole function. Myocardium, in the presence of redistribution, will have a better functional performance in coronary artery disease.

Adult↗
PubMed1992

Holter monitoring in patients with Wolff-Parkinson-White syndrome: with special reference to intermittent pre-excitation.

To characterize the intermittency of pre-excitation in patients with Wolff-Parkinson-White syndrome (W-P-W), we studied the ambulatory electrocardiograms (ECGs) of 48 patients (32 men and 16 women with a mean age of 38.5 years) with W-P-W. As documentation, at least one ECG for each patient had been performed during the follow-up period at our clinics. All cardiovascular drugs were discontinued for at least two days before Holter ECG monitoring. Through a careful beat-to-beat analysis of the QRS complex morphology, we were able to classify these patients into three groups: persistent pre-excitation in 26 (54.2%); intermittent pre-excitation in 17 (35.4%); and no pre-excitation in five (10.4%). There was no significant difference in sex, frequency of arrhythmias or mean heart rate among the three groups. Among the 17 showing intermittent pre-excitation, type A W-P-W was more prevalent (12 cases), and the ratio of pre-excitation to normal beats tended to decrease with age. Conduction normalized gradually with an increase in heart rate in 12 patients and suddenly in five other cases. There were two patients who showed a period of 2:1 pre-excitation intermingled with 1:1 pre-excitation and 1:1 normalized beats. These changes occurred with equal frequency both during the daytime and at night. These findings suggest that intermittent pre-excitation is a rather frequent phenomenon in patients with W-P-W. It occurs more frequently in type A patients and in older patients. Therefore, it may be an intermediate phase between manifest and concealed W-P-W.

Adolescent↗
PubMed1992

Peripheral and intracardiac concentrations of atrial natriuretic peptide in patients with heart disease.

To study the relationship between the plasma concentration of the atrial natriuretic peptide (ANP) and heart function and to discern the secretion pathway of ANP, we determined the peripheral plasma concentration of ANP in 18 heart patients and the intracardiac concentration of ANP in six heart patients during cardiac catheterization. All plasma was extracted through a Sep-Pak C18 cartridge by acid alcohol. The concentration of ANP was determined by a sensitive and specific radioimmunoassay method. We found that the plasma ANP concentration (pg/mL) in heart patients (ranging from 12 to 139, mean = 36.1 +/- 28.9) was statistically higher than that in normal adults (ranging from 8 to 20, mean = 12.4 +/- 3.3, n = 16; p less than 0.05). The ANP level in heart patients was inversely correlated with the left ventricular ejection fraction (r = -0.53, p less than 0.05) evaluated by radionuclide angiocardiography. The intracardiac level of ANP was 88 +/- 58 at the superior vena cava, 77 +/- 55 at the inferior vena cava, 124 +/- 68 at the right atrium, 98 +/- 64 at the right ventricle, 107 +/- 58 at the pulmonary artery, 98 +/- 52 at the left ventricle, 109 +/- 73 at the aorta and greater than 351 at the coronary sinus. In conclusion, ANP is mainly secreted via the coronary sinus into the atrial cavity. The peripheral plasma ANP concentration is higher in heart patients. It increases as the left ventricular ejection fraction decreases. Therefore, plasma ANP concentration may be a useful indicator for the assessment of cardiac function.

Adolescent↗