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Biomedical subjects

Lieng H Ling

Publications and source records attributed to Lieng H Ling.

8 recordsLinked to original sources
PubMed2006

Determining myocardial viability in chronic ischemic left ventricular dysfunction: a prospective comparison of rest-redistribution thallium 201 single-photon emission computed tomography, nitroglycerin-dobutamine echocardiography, and intracoronary myocardial contrast echocardiography.

BACKGROUND: Detection of viable myocardium (VM) has important therapeutic implications for chronic ischemic left ventricular (LV) systolic dysfunction. We compared the ability of nitroglycerin-dobutamine echocardiography (NTG-DE), intracoronary myocardial contrast echocardiography (MCE), and rest-redistribution thallium 201 single-photon emission computed tomography (RRT-SPECT) to detect VM in this setting. METHODS: Patients with LV ejection fraction (LVEF) <40% and multivessel coronary disease suitable for revascularization underwent NTG-DE, MCE, RRT-SPECT, and radionuclide ventriculography to determine baseline LVEF. Myocardial contrast echocardiography was performed using intracoronary injection of Albunex. Patients who underwent revascularization had 3-month postprocedural radionuclide ventriculography and transthoracic echocardiography to assess functional recovery. RESULTS: Of 512 myocardial segments in the 32 patients studied, 309 were akinetic or dyskinetic at baseline. Nitroglycerin alone increased regional thickening in 20% of segments with contractile reserve. By RRT-SPECT, 93% of nitroglycerin-responsive segments were viable. Myocardial contrast echocardiography had up to 85% sensitivity and 74% specificity for detection of VM diagnosed by RRT-SPECT. In the 23 patients who underwent revascularization, 54% of akinetic segments showed improved contractility, and mean LVEF increased from 32% to 37% (P = .04). Sensitivities and specificities for detecting functional recovery were 95% and 37% for RRT-SPECT, up to 87% and 48% for MCE, and 63% and 83% for a biphasic response during NTG-DE. CONCLUSIONS: In patients with chronic ischemic LV dysfunction, RRT-SPECT had the highest sensitivity, and NTG-DE, the best specificity for detection of VM. Nitroglycerin facilitated detection of VM and may be a useful adjunct to dobutamine stimulation.

Aged↗
PubMed2005

Reversal of myocardial injury using genetically modulated human skeletal myoblasts in a rodent cryoinjured heart model.

BACKGROUND: We hypothesized that combination therapy using human myoblasts and VEGF165 will lead to better prognosis in a failing heart. METHODS: Forty-eight female Wistar rats with cryoinjured hearts were randomized into non-treated normal (group-1, n=12), DMEM injected (group-2, n=10), myoblast-transplanted (group-3, n=12) and myoblast-hVEGF(165) (group-4, n=14). Ten days after cryoinjury, 200 microl DMEM containing 3x10(6) cells or without cells was injected into the injured myocardium. Animals were maintained on cyclosporine for 6 weeks post cell transplantation. Heart function was assessed by echocardiography. Animals were sacrificed and hearts were processed for histochemical and immunohistochemical studies. RESULTS: Histological examination showed survival of the donor myoblasts expressing lac-z and hVEGF165 in rat cardiac tissue. Fluorescent immunostaining for vWillebrand Factor-VIII and smooth muscle actin expression at low power microscope (x100) showed significantly higher blood vessel density in group-4 (31.25+/-1.82; 24.63+/-0.92) as compared to group-2 (13.29+/-1.0; p<0.001; 9.71+/-0.81, p<0.001) and group-3 (16.50+/-1.43, p<0.001; 14.5+/-1.34, p<0.001). Echocardiography showed that ejection fraction and fractional shortening of group-3 (93.36+/-1.52%, p=0.005; 75+/-3.75%, p=0.024) and group-4 (94.8+/-1.62%, p=0.003; 76.13+/-2.15%, p=0.011) significantly improved as compared to group-2 (81.8+/-3.3%, 55.1+/-7.18%). CONCLUSION: Myoblasts carrying of hVEGF165 are potential therapeutic transgene carriers for cardiac repair.

Analysis of Variance↗
PubMed2005

The mitral L wave: a marker of pseudonormal filling and predictor of heart failure in patients with left ventricular hypertrophy.

OBJECTIVES: We sought to examine the relationship of the mitral L wave with echocardiographic indexes of diastolic function and heart failure (HF) events in patients with left ventricular (LV) hypertrophy (LVH). BACKGROUND: The L wave, representing middiastolic transmitral flow, is of unknown clinical and prognostic significance in patients with LVH. Methods Consecutive echocardiograms performed during a 6-month period were screened for patients with LVH, normal LV ejection fraction, in sinus rhythm, and no significant valvular disease. Clinical and echocardiographic characteristics were analyzed, and patients were followed up for incident HF. RESULTS: Of 177 patients, the L wave was present in 35 (20%) (group I) and absent in 142 (group II). Patients in group I had higher early (E) to late (A) transmitral flow velocity (E/A) ratio (1.2 vs 0.8), shorter mitral E wave deceleration time (201 vs 225 milliseconds), lower pulmonary venous systolic/diastolic velocity ratio (1.1 vs 1.6), shorter LV isovolumic relaxation time (83 vs 94 milliseconds), larger left atrial volume (36 vs 23 mL/m 2 ), and higher E to early mitral annular velocity (E/E') ratio (septal E/E', 12.2 vs 9.1; lateral annular E/E', 10.9 vs 7.8) compared with group II (all P < .05). The difference between pulmonary venous atrial reversal and mitral A wave durations was > or = 30 milliseconds in more patients of group I (70% vs 6%, P < .001). During a mean follow-up of 12.0 months, 11 patients were hospitalized for HF. The L wave was associated with a hazard ratio of 4.7 ( P = .011) for incident HF, and remained a significant predictor (hazard ratio 4.2, P = .026) after adjustment for cardiovascular risk factors. CONCLUSIONS: In patients with LVH, the mitral L wave appears to be a marker of pseudonormal LV filling and predictor of future HF events.

Aged↗
PubMed2002

Atrial fibrillation complicating the course of degenerative mitral regurgitation: determinants and long-term outcome.

OBJECTIVES: The study was done to define the incidence, determinants and prognostic implications of onset of atrial fibrillation (AF) during follow-up of mitral regurgitation (MR) initially in sinus rhythm. BACKGROUND: The rates and clinical implications of AF in MR are undefined. METHODS: We analyzed the occurrence of AF under conservative management in two populations of patients with degenerative MR in sinus rhythm at diagnosis: 1) 360 patients (65 +/- 13 years, 74% men) with MR due to flail leaflets; and 2) 89 residents of Olmsted County, Minnesota (67 +/- 17 years, 56% men) with grade 3 or 4 MR due to simple mitral valve prolapse (MVP) diagnosed echocardiographically. RESULTS: In patients with MR due to flail leaflets, AF rates at 5 and 10 years were 18 +/- 3% and 48 +/- 6%, respectively, and the linearized rate was 5.0 +/- 0.7% per year. Development of AF during follow-up was independently associated with high risk of cardiac death or heart failure (adjusted risk ratio 2.23, p = 0.025). The AF rate at 10 years was higher in patients >or=65 years (75 +/- 10% vs. 24 +/- 6%, p < 0.0001) and in those with baseline left atrial (LA) dimension >or=50 mm (67 +/- 8% vs. 37 +/- 9%, p < 0.001). In multivariate analysis, independent baseline predictors of AF were age and LA diameter (both p < 0.01). In patients with MR due to MVP, similar rates of AF (41 +/- 7% vs. 44 +/- 6% at nine years, p > 0.50) and predictors of AF (age and LA dimension, both p < 0.006) were noted. CONCLUSIONS: In patients with degenerative MR in sinus rhythm at diagnosis, the incidence of AF occurring under conservative management is high and similar whether the cause of MR is flail leaflet or simple MVP. After onset of AF, an increased cardiac mortality and morbidity are both observed under conservative management. The risk of AF increases with advancing age and larger LA dimension. These data suggest that the clinical management of MR should take into account the high incidence, excess risk, and predictors of AF.

Aged↗
PubMed2002

Diagnostic value of mitral annular velocity for constrictive pericarditis in the absence of respiratory variation in mitral inflow velocity.

Respiratory variation of 25% or more in transmitral early diastolic filling (E) velocity is a well-recognized diagnostic feature of constrictive pericarditis (CP) that is useful for distinguishing it from restrictive cardiomyopathy. However, a subset of patients with CP do not exhibit the typical respiratory change. Recent data showed that mitral annular (E') velocity measured by Doppler tissue echocardiography (DTE) is markedly reduced in patients with restrictive cardiomyopathy whereas E' velocity is well-preserved in CP. This study evaluated the role of DTE for the diagnosis of CP when there is no characteristic respiratory variation of E velocity. From September 1999 to March 2001, 19 patients (17 men, 2 women; mean age, 57 +/- 13 years) with surgically confirmed CP underwent comprehensive echocardiography preoperatively, including pulsed wave and DTE examination with simultaneous recording of respiration. Nine (47%) of the 19 patients had less than 25% respiratory variation in E velocity. There was no significant difference in mitral inflow peak velocity, deceleration time, early-to-late ventricular filling ratio, and E' velocity between patients with and patients without respiratory variation of E velocity of 25% or more. Regardless of the presence or absence of a significant respiratory variation of E velocity, E' velocity was relatively normal (mean, 12 +/- 4 cm/s) in all patients with CP. In conclusion, E' velocity is well preserved in patients with isolated CP even when there is no characteristic respiratory variation of E velocity. Thus, when the respiratory variation in Doppler E velocity is blunted or absent during the evaluation of suspected CP in patients with restrictive mitral inflow velocity, preserved E' velocity shown by DTE should support the diagnosis of CP over a primary myocardial disease.

Adult↗