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Biomedical subjects

Homer Yang

Publications and source records attributed to Homer Yang.

13 recordsLinked to original sources
PubMed2006

Acute diastolic dysfunction in thoracoabdominal aortic aneurysm surgery.

PURPOSE: To report transesophageal echocardiographic (TEE) findings consistent with intraoperative acute diastolic dysfunction in a series of patients undergoing thoracoabdominal aortic aneurysm (TAAA) repair. METHODS: A series of nine consecutive patients underwent TAAA repair with intraoperative TEE monitoring. Surgical repair was performed with the adjunct of a left atrio-femoral bypass. Invasive arterial and venous pressures were monitored. Intraoperative TEE was utilized to assess the diastolic function before, and during aortic cross clamping. Diastolic dysfunction was defined as a mitral inflow pulsed wave Doppler (E: A ratio) < 1. RESULTS: All patients demonstrated an E: A ratio > 1 (1.3 +/- 0.08) before aortic cross clamping. During cross clamp, the E: A ratio decreased to < 1 (0.75 +/- 0.05) in six of nine patients consistent with diastolic dysfunction. The three patients who did not develop E: A changes were receiving ss-blockers pre-operatively. Patients with diastolic dysfunction were treated with nitroglycerin infusions, which resulted in restoration of their E: A ratios > 1 (1.2 +/- 0.09). Three of the patients with intraoperative diastolic dysfunction developed postoperative myocardial infarction. CONCLUSIONS: Chronic diastolic dysfunction is a well-known entity. This report describes acute diastolic dysfunction, which was observed frequently in patients undergoing TAAA during aortic cross clamp. Further research is required to confirm this phenomenon and determine its possible association with increased postoperative cardiac morbidity.

Acute Disease↗
PubMed2006

Rationale, design, and organization of the PeriOperative ISchemic Evaluation (POISE) trial: a randomized controlled trial of metoprolol versus placebo in patients undergoing noncardiac surgery.

BACKGROUND: Noncardiac surgery is associated with significant cardiovascular mortality, morbidity, and cost. Small trials of beta-blockers suggest that they may prevent cardiovascular events in patients undergoing noncardiac surgery, but trial results are inconclusive. We have initiated the POISE trial to definitively establish the effects of beta-blocker therapy in patients undergoing noncardiac surgery. METHODS: The POISE trial is a blinded, randomized, and controlled trial of controlled-release metoprolol versus placebo in 10000 patients at risk for a perioperative cardiovascular event who are undergoing noncardiac surgery. Patients will receive the study drug 2 to 4 hours before surgery and subsequently for 30 days. The primary outcome is a composite of cardiovascular death, nonfatal myocardial infarction, and nonfatal cardiac arrest at 30 days. Patients will also be followed for events at 1 year. RESULTS: To date, the POISE trial has recruited >6300 patients in 182 centers in 21 countries. Currently, the patients' mean age is 69 years; 63% are males, 43% have a history of coronary artery disease, 43% have a history of peripheral arterial disease, and 30% have diabetes. Most participants have undergone vascular (42%), intraabdominal (23%), or orthopedic (19%) surgery. CONCLUSIONS: The POISE trial is a large international trial that will provide a reliable assessment of the effects of beta-blocker therapy in patients undergoing noncardiac surgery.

Adrenergic beta-Antagonists↗
PubMed2006

The effects of perioperative beta-blockade: results of the Metoprolol after Vascular Surgery (MaVS) study, a randomized controlled trial.

BACKGROUND: Patients undergoing vascular surgery comprise the highest risk group for perioperative cardiac mortality and morbidity after noncardiac procedures. Many current guidelines recommend the use of beta-blockers in all patients undergoing vascular surgery. We report a trial of the perioperative administration of metoprolol and its effects on the incidence of cardiac complications at 30 days and 6 months after vascular surgery. METHODS: Patients undergoing abdominal aortic surgery and infrainguinal or axillofemoral revascularizations were recruited to a double-blind randomized controlled trial of perioperative metoprolol versus placebo. Patients were randomized to receive study medication, starting 2 hours preoperatively until hospital discharge or maximum of 5 days postoperatively. Primary outcome were postoperative 30-day composite incidence of nonfatal myocardial infarction, unstable angina, new congestive heart failure, new atrial or ventricular dysrhythmia requiring treatment, or cardiac death. RESULTS: Patients were randomized to receive either metoprolol (n = 246) or placebo (n = 250). Primary outcome events at 30 days postoperative occurred in 25 (10.2%) versus 30 (12.0%) (P = .57) in metoprolol and placebo groups, respectively (relative risk reduction 15.3%, 95% CI -38.3% to 48.2%). Observed effects at 6 months were not significantly different (P = .81) (relative risk reduction 6.2%, 95% CI% -58.4% to 43.8%). Intraoperative bradycardia requiring treatment was more frequent in the metoprolol group (53/246 vs 19/250, P = .00001), as was intraoperative hypotension requiring treatment (114/246 vs 84/250, P = .0045). CONCLUSION: Our results showed metoprolol was not effective in reducing the 30-day and 6-month postoperative cardiac event rates. Prophylactic use of perioperative beta-blockers in all vascular patients is not indicated.

Adrenergic beta-Antagonists↗
PubMed2005

How strong is the evidence for the use of perioperative beta blockers in non-cardiac surgery? Systematic review and meta-analysis of randomised controlled trials.

OBJECTIVE: To determine the effect of perioperative beta blocker treatment in patients having non-cardiac surgery. DESIGN: Systematic review and meta-analysis. DATA SOURCES: Seven search strategies, including searching two bibliographic databases and hand searching seven medical journals. STUDY SELECTION AND OUTCOMES: We included randomised controlled trials that evaluated beta blocker treatment in patients having non-cardiac surgery. Perioperative outcomes within 30 days of surgery included total mortality, cardiovascular mortality, non-fatal myocardial infarction, non-fatal cardiac arrest, non-fatal stroke, congestive heart failure, hypotension needing treatment, bradycardia needing treatment, and bronchospasm. RESULTS: Twenty two trials that randomised a total of 2437 patients met the eligibility criteria. Perioperative beta blockers did not show any statistically significant beneficial effects on any of the individual outcomes and the only nominally statistically significant beneficial relative risk was 0.44 (95% confidence interval 0.20 to 0.97, 99% confidence interval 0.16 to 1.24) for the composite outcome of cardiovascular mortality, non-fatal myocardial infarction, and non-fatal cardiac arrest. Methods adapted from formal interim monitoring boundaries applied to cumulative meta-analysis showed that the evidence failed, by a considerable degree, to meet standards for forgoing additional studies. The individual safety outcomes in patients treated with perioperative beta blockers showed a relative risk for bradycardia needing treatment of 2.27 (95% CI 1.53 to 3.36, 99% CI 1.36 to 3.80) and a nominally statistically significant relative risk for hypotension needing treatment of 1.27 (95% CI 1.04 to 1.56, 99% CI 0.97 to 1.66). CONCLUSION: The evidence that perioperative beta blockers reduce major cardiovascular events is encouraging but too unreliable to allow definitive conclusions to be drawn.

Adrenergic beta-Antagonists↗
PubMed2003

Detrimental effects of papaverine on the human internal thoracic artery.

OBJECTIVE: We sought to determine the effects of papaverine on human and canine internal thoracic artery function and structure. METHODS: Vascular function was assessed with wire myography, and apoptosis was examined with confocal microscopy in arteries stained with ApopTag. RESULTS: Acetylcholine-induced endothelium-dependent relaxation in phenylephrine-precontracted arteries was significantly impaired by papaverine treatment in both human and canine internal thoracic arteries (maximal relaxation: 68.35% +/- 7.13% vs 47.5% +/- 9.32% in human arteries and 74.8% +/- 5.5% vs 34.3% +/- 8.5% in canine arteries) but not by incubation with acidified saline solution (pH 3.9, which is equivalent to the pH of 10(-2) mol/L papaverine solution) in canine internal thoracic arteries. Contraction of human internal thoracic arteries to phenylephrine or to U46619 was not significantly affected by papaverine treatment and neither was the contraction of canine internal thoracic arteries to phenylephrine. Total apoptotic endothelial and smooth muscle cells were significantly greater in papaverine-treated human and canine internal thoracic arteries. CONCLUSIONS: Papaverine impairs endothelial function and triggers apoptosis of endothelial and smooth muscle cells of human and canine internal thoracic arteries. The long-term consequence of this impairment on vascular function is not known. Until this question is answered, it will be prudent to use other vasodilators that are less damaging to the internal thoracic artery for cardiac surgery.

Animals↗
PubMed2002

Transesophageal echocardiography in the management of left atrio-femoral bypass during thoracoabdominal aortic aneurysm repair: a case report.

PURPOSE: To describe the utility of transesophageal echocardiography (TEE) in a patient undergoing thoracoabdominal aneurysm (TAA) surgery using left atrio-femoral bypass (LAFB). CLINICAL FEATURES: A 57-yr-old female patient underwent repair of type II TAA. As per institutional routine, LAFB technique was used. Initial difficulty with the pump flow was encountered. TEE images showed that the left atrial cannula was positioned against the left atrial wall. The cannula position was adjusted and the pump flow was established. During different stages of the surgery, TEE was used to monitor the left ventricular cavity size and its function. This allowed the adjustment of LAFB pump flow relative to left ventricular filling and optimal fluid resuscitation in order to maintain both upper and lower body perfusion. CONCLUSION: In this patient, TEE was useful to confirm the correct position of the left atrial cannula and for hemodynamic management during LAFB.

Aortic Aneurysm, Abdominal↗
PubMed2002

Pulmonary thromboendarterectomy in a patient with giant cell arteritis.

This report describes the case of a young woman presenting with signs and symptoms of chronic thromboembolic pulmonary hypertension who underwent pulmonary thromboendarterectomy (PTE) with concomitant coronary artery bypass. She died in the intensive care unit 1 day postoperatively. At autopsy the patient was found to have giant cell arteritis of the pulmonary arteries and ascending aorta. It is important to differentiate this disease from chronic thromboembolic pulmonary hypertension because its management and that of systemic vasculitis differs considerably.

Adult↗
PubMedDate not supplied

Induction with sevoflurane-remifentanil is comparable to propofol-fentanyl-rocuronium in PONV after laparoscopic surgery.

PURPOSE: To compare sevoflurane-remifentanil induction and propofol-fentanyl-rocuronium induction with regards to the frequency of moderate to severe postoperative nausea and vomiting (PONV) in the first 24 hr after laparoscopic day surgery. METHODS: After informed consent, 156 ASA physical status class I to III patients undergoing laparoscopic cholecystectomy or tubal ligation were randomized to either induction with sevoflurane 8%, N(2)O 67% and iv remifentanil 1 to 1.5 microg.kg(-1) or induction with iv fentanyl 2 to 3 microg.kg(-1), propofol 2 mg.kg(-1), and rocuronium 0.3 to 0.5 mg.kg(-1). All patients received iv ketorolac 0.5 mg.kg(-1) at induction and sevoflurane-N(2)O maintenance anesthesia with rocuronium as needed. PONV was treated with iv ondansetron, droperidol, or dimenhydrinate; postoperative pain was treated with opioid analgesics. Patients were followed for 24 hr with regards to PONV and pain. Intubating conditions, induction and emergence times, time to achieve fast-track discharge criteria, and drug costs were measured. RESULTS: No differences were seen between the two groups in their frequencies of 24-hr moderate to severe PONV and postoperative pain, or in their intubating conditions, induction and emergence times, and time to achieve fast-track discharge criteria. Patients undergoing sevoflurane-remifentanil induction received more morphine (11 mg vs 8 mg; P < 0.001) in the postanesthetic care unit. Sevoflurane-remifentanil induction resulted in similar anesthetic and total drug costs for both procedures. CONCLUSION: We did not demonstrate any difference in PONV, pain, or anesthetic/recovery times or costs between the sevoflurane and propofol groups. Sevoflurane-remifentanil induction is a feasible technique for anesthetic induction.

Adult↗