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Biomedical subjects

Eric H Yang

Publications and source records attributed to Eric H Yang.

12 recordsLinked to original sources
PubMed2006

Usefulness of two-dimensional speckle strain for evaluation of left ventricular diastolic deformation in patients with coronary artery disease.

We investigated the influence of > or =70% luminal coronary artery stenosis on regional diastolic deformation at rest using 2-dimensional strain echocardiography. We prospectively imaged patients during/within 24 hours of coronary angiography. Longitudinal systolic (SRs), early (SRe), and late diastolic strain rates, systolic, early, and late diastolic strain and times to isovolumic relaxation and peak SRe were measured in the 3 major vascular territories. Regions subtended by > or =70% coronary stenosis were labeled ischemic. Ischemic regions were compared with the same region in patients without significant coronary stenosis. Of 61 enrolled patients (38 men), 39 had > or =70% coronary stenosis (1 vessel in 14, 2 vessels in 15, 3 vessels in 10), and 15 had normal coronary arteries. There were no significant differences between the normal and ischemic groups with regard to age (59 +/- 13 vs 64 +/- 10 years, p = 0.20), clinical variables (dyslipidemia, smoking, diabetes), systolic (130 +/- 26 vs 139 +/- 31 mm Hg, p = 0.38) or diastolic (72 +/- 13 vs 72 +/- 11 mm Hg, p = 0.81) blood pressure and ejection fraction (58 +/- 12% vs 56 +/- 11%, p = 0.66). SRs and SRe were significantly decreased in ischemic compared with normal regions in all vascular distributions. SRs and SRe together (values below cutoff) or SRe alone were the most specific (93%) and SRe or SRs below cutoff the most sensitive (93%) parameters for detecting ischemic regions. In conclusion, analysis of regional deformation by 2-dimensional strain echocardiography enables detection of significantly diseased coronary arteries at rest. Altered diastolic deformation at rest identifies regions subtended by > or =70% coronary stenosis with high specificity.

Coronary Artery Disease↗
PubMed2006

Narrative review: reperfusion strategies for ST-segment elevation myocardial infarction.

Optimal treatment for ST-segment elevation myocardial infarction depends on early diagnosis and rapid selection of the appropriate reperfusion strategy. Primary percutaneous coronary intervention (PCI) is the preferred reperfusion strategy at PCI-capable hospitals. For hospitals without PCI capability, there are 2 reperfusion strategies, primary PCI and thrombolytic therapy, which are both supported by clinical evidence and national guidelines. Transferring patients for primary PCI may cause delays and requires established, proven protocols, systems, and networks to achieve minimal door-to-balloon times. The authors review the available data and present a systematic, evidence-based approach in a simple framework to enable noncardiovascular and cardiovascular physicians to select the optimal reperfusion strategy. The framework is based on available data from clinical trials and local circumstances from clinical practice by incorporating duration of symptoms (fixed ischemia time) and anticipated transport delays to a PCI-capable facility (incurred ischemia time).

Aged↗
PubMed2006

Comparison of usefulness of echocardiographic Doppler variables to left ventricular end-diastolic pressure in predicting future heart failure events.

We sought to determine whether the echocardiographic Doppler parameters of left ventricular diastolic dysfunction predict future heart failure (HF) events and, if so, which parameters best predict HF. We also examined whether the predictive ability of echocardiographic Doppler parameters was related to their prediction of left ventricular end-diastolic pressure (LVEDP). We studied patients who underwent cardiac catheterization and echocardiography performed within a 30-day period. The end point was HF, defined as new-onset or recurrent HF diagnosed by a physician and requiring the initiation or modification of treatment of HF. We identified 289 patients (mean age 63.5 +/- 12.6 years) with a mean follow-up of 10.9 +/- 10.2 months. A total of 24 HF events occurred. LVEDP was a significant predictor of HF univariately and independently in multiple regression models after adjustment for ejection fraction. In Cox models adjusted for age, gender, LVEDP, and ejection fraction, only the left atrial volume index and early mitral inflow to early diastolic tissue velocity (E/e') ratio remained predictive of HF. A multiple regression model, including all echocardiographic variables, showed a persistent, although attenuated, relation of early to late mitral inflow velocity (E/A) ratio and E/e' with LVEDP (p = 0.06 and p = 0.002, respectively). The addition of E/e' or the left atrial volume indexed to body surface area, but not E/A, to the clinical history and left ventricular ejection fraction provided incremental prognostic information. A LVEDP of > or =20 mm Hg, E/e' ratio of > or =15, and left atrial volume index of > or =23 ml/m(2) identified those with a higher risk of HF. In conclusion, invasively determined LVEDP is an independent predictor of future HF events. E/e' and the left atrial volume indexed to body surface area are the best independent predictors of future HF and provide prognostic information incremental to the clinical history and left ventricular ejection fraction.

Adult↗
PubMed2006

Modern management of acute myocardial infarction.

Acute myocardial infarction (AMI) is a subset of the acute coronary syndromes and can be classified as being either a ST-segment elevation myocardial infarction (STEMI) or a non-ST-elevation myocardial infarction (NSTEMI). A clear distinction between STEMI and NSTEMI is essential because of the differences in management. The purpose of this review was to first discuss the epidemiology, pathophysiology, and diagnosis of AMI. The risk stratification and therapy of patients with STEMI and NSTEMI will then be reviewed as well as the complications of AMI.

Acute Disease↗
PubMed2006

Evolving treatment strategies for chronic refractory angina.

Chronic refractory angina is a term used to describe patients who, despite optimal medical therapy, have both angina and objective evidence of ischaemia. It is estimated that 5-15% of the 12 million patients with chronic angina in the US meet the criteria for having refractory angina. This review focuses on the following evolving pharmacological therapies for chronic refractory angina: L-arginine, ivabradine, ranolazine, nicorandil and trimetazidine. Evolving devices and invasive procedures including enhanced external counterpulsation, spinal cord stimulation, and transmyocardial revascularisation are also briefly discussed.

Acetanilides↗
PubMed2005

Emergency coronary artery bypass surgery for percutaneous coronary interventions: changes in the incidence, clinical characteristics, and indications from 1979 to 2003.

OBJECTIVES: The purpose of the current study was to evaluate the changes in incidence, clinical characteristics, and indications for emergency coronary artery bypass grafting (CABG) in patients undergoing percutaneous coronary intervention (PCI) from 1979 to 2003. BACKGROUND: Emergency CABG after PCI is associated with significant morbidity and mortality. METHODS: Data from 23,087 patients who underwent PCI at Mayo Clinic from 1979 to 2003 were analyzed. Patients were divided into three groups: the "pre-stent" era, 1979 to 1994 (n = 8,905); the "initial stent era," 1995 to 1999 (n = 7,605); and the "current stent era," 2000 to 2003 (n = 6,577). RESULTS: Although patients undergoing PCI in the recent time periods had more high-risk features, there was a significant decrease in the incidence of emergency CABG from 2.9% to 0.7% to 0.3% across the groups (p < 0.001). Patients requiring emergency surgery in the recent time periods had a higher prevalence of hypertension, prior revascularization, and left ventricular dysfunction (ejection fraction <40%), as well as more complex coronary lesions. Fewer patients in the current stent era had coronary artery dissections and abrupt vessel closure requiring emergency CABG. The in-hospital mortality rate for emergency CABG patients remains unchanged and ranges from 10% to 14%. CONCLUSIONS: The current study demonstrates that despite the increase in high-risk patients undergoing PCI, there has been a marked decrease in the incidence of patients requiring emergency CABG. However, the in-hospital mortality rate for those requiring emergency CABG remains high and unchanged.

Aged↗
PubMed2005

Lipoprotein-associated phospholipase A2 is an independent marker for coronary endothelial dysfunction in humans.

OBJECTIVE: The purpose of the current study was to determine whether lipoprotein-associated phospholipase A2 (Lp-PLA2) is associated with coronary endothelial dysfunction and is a predictor of endothelial dysfunction in humans. METHODS AND RESULTS: Patients (172) with no significant coronary artery disease (<30% stenosis) undergoing assessment of coronary endothelial function were studied. Endothelial function was assessed by the change in coronary blood flow and coronary artery diameter in response to intracoronary acetylcholine. Plasma concentrations of Lp-PLA2 were measured, and patients were divided into tertiles. Patients in tertiles 2 and 3 had a significantly lower change in coronary blood flow (63.8+/-73.2 and 32.0+/-71.7 versus 78.4+/-73.2%; P<0.001) and greater epicardial coronary artery vasoconstriction (-14.1+/-14.7 and -23.3+/-25.1 versus -9.5+/-15.2% mean diameter change; P<0.001) in response to acetylcholine. Patients with coronary endothelial dysfunction had significantly higher serum concentrations of Lp-PLA2 than those with normal endothelial function (246.2+/-71.6 versus 209+/-56.7 ng/mL; P=0.001). The odds ratio for coronary endothelial dysfunction in patients with Lp-PLA2 in the highest tertile was 3.3 (95% CI, 1.6 to 6.6). CONCLUSIONS: Lp-PLA2 is independently associated with coronary artery endothelial dysfunction and is a strong predictor of endothelial dysfunction in humans.

1-Alkyl-2-acetylglycerophosphocholine Esterase↗
PubMed2005

Angina pectoris with a normal coronary angiogram.

Angina in the setting of a normal angiogram (NOCAD) occurs in 20-30% of patients undergoing coronary angiography. The etiologies of NOCAD can be anatomically classified into three groups: epicardial disease, coronary microvascular dysfunction, and noncoronary disease. Epicardial disease resulting in NOCAD includes endothelial dysfunction, coronary artery spasm, and coronary artery bridging. Microvascular dysfunction may be secondary to hypertension, cardiomyopathy, infiltrative disease, valvular disease, or idiopathic. Noncoronary artery disease states involving other organs systems such as the pulmonary, gastrointestinal, or musculoskeletal systems can also result in NOCAD. This review focuses on the coronary etiologies of NOCAD. The pathophysiology of disease is discussed as well as a systematic diagnostic strategy. Potential therapeutic options and prognosis are also reviewed.

Clinical Trials as Topic↗
PubMed2004

Coronary hemodynamics in patients with symptomatic hypertrophic cardiomyopathy.

The purpose of this study was to analyze coronary hemodynamics and determine a possible mechanism for microvascular dysfunction in patients with symptomatic hypertrophic cardiomyopathy (HC). Although patients with HC have been shown to have microvascular dysfunction and reduced coronary flow reserve (CFR), the mechanism by which this occurs is not well understood. We studied coronary hemodynamics in 8 patients with symptomatic HC and compared them with 8 matched controls. Compared with controls, patients with HC had higher coronary blood flow, lower coronary resistance, and lower CFR. Patients with HC also had abnormal phasic coronary flow characteristics. These results suggest that the reduction of CFR in patients with HC may be secondary to near maximal vasodilation of the microcirculation in the basal state.

Adult↗
PubMed2004

Current and future treatment strategies for refractory angina.

Patients with refractory angina are not candidates for revascularization and have both class III or IV angina and objective evidence of ischemia despite optimal medical therapy. An estimated 300,000 to 900,000 patients in the United States have refractory angina, and 25,000 to 75,000 new cases are diagnosed each year. This review focuses on treatment strategies for refractory angina and includes the mechanism of action and clinical trial data for each strategy. The pharmacological agents that have been used are ranolazine, ivabradine, nicorandil, L-arginine, testosterone, and estrogen; currently, only L-arginine, testosterone, and estrogen are approved by the Food and Drug Administration. Results with the noninvasive treatments of enhanced external counterpulsation and transcutaneous electrical nerve stimulation are provided. Invasive treatment strategies including spinal cord stimulation, transmyocardial revascularization, percutaneous myocardial revascularization, and gene therapy are also reviewed.

Angina Pectoris↗