Biomedical subjects

Mason Shing Young

Publications and source records attributed to Mason Shing Young.

8 recordsLinked to original sources

PubMed2006

Increased endothelial monocyte adhesiveness is related to clinical outcomes in chronic heart failure.

BACKGROUND: Vascular inflammation and endothelial dysfunction are evident in patients with chronic heart failure (CHF). We hypothesized that circulating peripheral blood mononuclear cells (PBMCs) may be activated and the resultant increased endothelial monocyte adhesion may be functionally and pathophysiologically relevant in CHF. In the present study, we investigated the clinical significance of the activity of PBMCs in patients with CHF. METHODS: PBMCs were isolated from 34 CHF patients, from 10 healthy volunteers (normal control group) and from 17 patients admitted for investigation of suspected coronary artery disease (disease control group). In each patient, the adhesiveness of PBMCs to cultured human aortic endothelial cells (HAECs) with or without tumor necrosis factor-alpha (TNF-alpha) stimulation was determined. Major adverse cardiac events (death, heart transplantation or hospitalization with worsening heart failure) were determined in the 34 CHF patients during a median follow-up period of 182 days. RESULTS: Compared with those from both control groups and from mild CHF patients, PBMCs isolated from severe CHF patients adhered more to the HAECs. The endothelial adhesiveness of PBMCs correlated positively with the circulating levels of CAMs and can supply prognostic information in CHF patients. The difference between event-free curves based on the median levels of endothelial-PBMC adhesion was significant (log rank test, p=0.0139). CONCLUSIONS: Endothelial adhesiveness of PBMCs is increased and correlated to clinical outcomes, and may be pathophysiologically relevant to the progression of CHF.

Aged↗

PubMed2005

L-arginine improves endothelial function and reduces LDL oxidation in patients with stable coronary artery disease.

BACKGROUND: We investigated the effects of oral L-arginine on endothelial function, intravascular oxidative stress, and circulating inflammatory markers in patients with stable coronary artery disease (CAD). METHODS: Thirty-one stable CAD patients were randomly assigned to oral L-arginine (10 g) or vitamin C (500 mg, an antioxidant, as active control) daily for 4 weeks, with crossover to the alternate therapy after 2 weeks off therapy, in this study. Brachial artery endothelial function studies were performed and serum concentrations of lipids and inflammatory markers were measured at baseline, at the end of each 4-week treatment period and at the 2-week wash-out period. Susceptibility of low-density lipoprotein (LDL) particles to oxidation, a marker of oxidative stress, was determined in 11 patients at random before and after 4-week treatment of oral L-arginine. RESULTS: We demonstrates that consumption of either L-arginine or vitamin C significantly increased brachial artery flow-mediated dilatation (mean diameter change from baseline of 4.87%, P<0.0001 and of 3.17%, P=0.0003, respectively). Neither oral L-arginine nor vitamin C affected lipid profiles and circulating levels of inflammatory markers. However, in the 11 patients whose LDL susceptibility to oxidation was determined, lag time significantly increased by 27.1% (P=0.045) after consumption of L-arginine for 4 weeks. CONCLUSIONS: Oral L-arginine supplement improved endothelial function and reduced LDL oxidation in stable CAD patients.

Administration, Oral↗

PubMed2004

Independent prognostic value of elevated high-sensitivity C-reactive protein in chronic heart failure.

BACKGROUND: The serum concentration of C-reactive protein (CRP) is mildly elevated in patients with chronic congestive heart failure (CHF), but this level falls well within the range found in healthy subjects. Standard clinical assays for CRP lack sensitivity within the low reference range and thus cannot be used effectively for routine clinical risk prediction. Because assays for high-sensitivity CRP (hsCRP) are now available, we can measure hsCRP to determine its predictive value for the prognosis of patients with CHF. METHODS: Serum levels of hsCRP in 108 patients with CHF and left ventricular ejection fraction (LVEF) <50% were examined. Major adverse cardiac events (death, heart transplantation, or hospitalization with worsening heart failure) during a median follow-up period of 403 days were determined. RESULTS: The concentrations of hsCRP in this study population were significantly increased with the severity of CHF. In a multivariate analysis, LVEF and serum levels of hsCRP were independent significant predictors for adverse outcomes in these patients (hazard ratio, 3.714, P =.024, and hazard ratio, 2.584, P =.047, respectively). However, hsCRP was minimally correlated with LVEF (r = -0.167, P =.084). Further analysis indicated that hsCRP might identify a different high-risk group and could improve risk stratification beyond that of LVEF. CONCLUSIONS: These findings suggest that an elevated level of hsCRP is an independent predictor of prognosis in CHF and can provide additional prognostic information for the risk stratification and treatment in patients with chronic CHF.

Aged↗

PubMed2004

Implantation of a passive fixation dual chamber pacemaker in a patient with persistent left superior vena cava.

Electrode instability and displacement have been reported in patients who underwent pacemaker implantation via persistent left superior vena cava. An active-fixation system, and sometimes epicardial pacing, is necessary to maintain pacing stability. We report the case of a 76-year-old man with a left superior vena cava who required dual-chamber permanent pacing. Passive-fixation atrial and ventricular leads were successfully inserted and produced good long-term pacing and sensing. To the best of our knowledge, this is the first reported case of implantation of a dual-chamber pacemaker via persistent left superior vena cava in Taiwan.

Aged↗

PubMed2003

The prognostic value of circulating soluble cell adhesion molecules in patients with chronic congestive heart failure.

BACKGROUND: Circulating soluble (s) cell adhesion molecules (CAMs) are elevated in patients with congestive heart failure (CHF) and may play an important role in the pathogenesis of CHF by mediating the cell-cell interactions of the immune response. However, clinical data about the prognostic value of sCAMs are sparse. The purpose of this study is to determine whether various sCAMs can provide prognostic information in patients with CHF. METHODS: We measured circulating levels of three sCAMs (vascular cell adhesion molecule-1, intercellular adhesion molecule-1, and sP-selectin) in 74 patients with symptomatic chronic CHF and left ventricular ejection fraction (LVEF) <50%. We compared these levels with those of a group of 19 age-matched control subjects. Major adverse cardiac events (death, heart transplantation or hospitalization with worsening CHF) during a median follow-up period of 240 days were determined. RESULTS: The concentrations of the three sCAMs in the 74 patients with CHF were significantly associated with one another. Their levels were higher than those of the control subjects and increased with the severity of CHF. Significantly higher sCAM levels were noted in those patients who had major adverse cardiac events during the follow-up period. There were significant negative correlations between LVEF and sCAMs. However, only high levels of sP-selectin were found to be an independent significant predictor of CHF by Cox proportional hazards analysis. CONCLUSIONS: These findings indicate that the levels of these three sCAMs increase with the severity of CHF and are related to clinical outcomes. Among them, high levels of sP-selectin can provide prognostic information independently in patients with CHF.

Aged↗

PubMed2003

Impairment of coronary microvascular function in patients with neurally mediated syncope.

Recent evidence suggests that myocardial ischemia may occur in patients with neurally mediated syncope and normal coronary angiograms. This study was conducted to evaluate if coronary microvascular function is impaired in such patients. Coronary hemodynamic studies and head-up tilt table tests (HUTs) were performed on 30 consecutive patients with normal coronary angiograms and recurrent syncope. Another ten subjects with atypical chest pain and no evidence of myocardial ischemia or syncope served as a control. Great cardiac vein flow (GCVF) and coronary sinus flow (CSF) were measured by the thermodilution method at baseline and after dipyridamole infusion (0.56 mg/kg i.v. for 4 minutes). Coronary flow reserve (CFR), derived from CSF and GCVF, was significantly lower in the 15 patients with positive HUT than in the other 15 patients with negative HUT (1.75 +/- 0.48 vs 2.64 +/- 0.8, P < 0.01 and 2.29 +/- 0.45 vs 3.07 +/- 0.63, P < 0.01, respectively). Ischemic-like ECG was noted during treadmill exercise test in 40% of the former and in 7% of the latter group (P = 0.01). There was no significant difference in CFR between patients with negative HUT and control subjects. Coronary microvascular function was impaired in syncopal patients with positive HUT and relatively preserved in those with negative HUT, suggesting the possible linkage between coronary microvascular dysfunction and the development of neurally mediated syncope.

Case-Control Studies↗

PubMed2003

Safe right bundle branch block pattern during permanent right ventricular pacing.

It is known that an electrocardiogram (ECG) after transvenous right ventricular (RV) pacing should yield left bundle branch block (LBBB) QRS patterns. When right bundle branch block (RBBB) pacing morphology appears in a patient with a permanent or temporary transvenous RV pacemaker, myocardial perforation or malposition of the pacing lead must be ruled out, even though the patient may be asymptomatic. We report a case of a 77-year-old man who underwent permanent transvenous VDD pacemaker implantation for symptomatic heart block. The postoperative ECG revealed a RBBB pacing configuration, but his chest X-ray and echocardiographic studies confirmed uncomplicated RV pacing. We review and discuss the literature concerning the differential diagnosis of such a safe RBBB ECG pattern.

Aged↗

PubMed2002

Development of an echocardiographic method for choosing the best fitting single-pass VDD lead.

To achieve stable single-lead VDD pacing, a selection of the electrode with the optimal distance between the lead tip and the floating atrial dipole (AV distance [AVD]) is important. The authors hypothesized that the size of the right heart chambers may affect atrial sensing, and that measurement of their internal dimension at end-diastole (RHIDd) in the apical four chamber view by transthoracic echocardiography may aid in choosing the proper AVD. Twenty-six consecutive cases that had undergone VDD pacer implantation using the conventional chest X ray were examined retrospectively by the echocardiographic method. The chest x-ray method properly selected a lead with optimal atrial sensing, defined as minimum P wave amplitude > or = 1.0 mV, for only 20 (77%) of 26 patients. By comparing these results with their respective RHIDd, a cut-off point of 13 cm was obtained that indicated a criterion for choosing the proper AVD. The indication was that if the RHIDd was > or = 13 cm, a lead with an AVD of 15.5/16 cm should have been used; if the RHIDd was < 13 cm, a lead with an AVD of 13/13.5 cm should have been chosen. Using the echocardiographic method, all six patients who had suboptimal atrial sensing could be identified and classified as having missized (four undersized; two oversized) permanent leads. In conclusion, the described method provides a promising preoperative assessment of the best fitting electrode length in single lead VDD pacing. A prospective study is ongoing to verify its applicability.

Adult↗