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Biomedical subjects

A Y Fung

Publications and source records attributed to A Y Fung.

23 records · Page 2Linked to original sources
PubMed1986

Safety of helicopter transport and out-of-hospital intravenous fibrinolytic therapy in patients with evolving myocardial infarction.

Of 150 consecutive patients with acute myocardial infarction transported by helicopter for acute intervention, 55 had intravenous thrombolytic therapy (tissue plasminogen activator in 12, streptokinase in 43) initiated prior to transfer. Patients were transported 55 +/- 10 ground miles in 17 +/- 6 minutes and no patient died or experienced bleeding or hemodynamic instability during transfer. Patients receiving thrombolytic therapy had a higher incidence of arrhythmias during transit compared to the untreated group, ventricular tachycardia in six and third-degree atrioventricular block in one compared to ventricular tachycardia in one patient, respectively (p = 0.005). However, these arrhythmias were transient and did not require cardioversion, temporary pacing, or further antiarrhythmic medical treatment. Chest pain was relieved or decreased more frequently in the patients receiving thrombolytic therapy vs. those untreated; 21 of 55 vs. 21 of 95 respectively (p = 0.04). Immediate coronary angiography confirmed a higher incidence and more complete infarct vessel patency (34/55 vs. 30/95) in the patients receiving tissue plasminogen activator or streptokinase (p less than 0.001). Thus, helicopter transfer of patients with evolving myocardial infarction is safe, and early initiation of thrombolytic therapy is associated with increased infarct vessel patency and benign reperfusion arrhythmias.

Aircraft↗
PubMed1984

Increased sensitivity to norepinephrine cardiac arrhythmias in the deoxycorticosterone acetate high salt rat before the onset of hypertension.

To determine whether salt loading increases the sensitivity of the myocardium to fatal arrhythmias induced by norepinephrine, four groups of Sprague-Dawley rats were studied. Group I received both saline (0.9%) as drinking water and deoxycorticosterone acetate (DOCA) (0.5 mg/kg, 3 times) for 14 days (DOCA high salt group); group II received only 0.9% saline as drinking water (high salt group); group III received DOCA in the same dose regime, but tap water to drink (DOCA group); and group IV received tap water (control). Under pentobarbital anesthesia, norepinephrine was infused and electrocardiogram and blood pressure were monitored. The DOCA high salt group developed arrhythmias significantly (p less than 0.05) earlier than at lower norepinephrine doses. The dose at which 50% mortality occurred was 20 micrograms . kg-1 . min-1 in DOCA high salt group, 37 micrograms . kg -1 . min-1 in high salt group, 40 micrograms . kg-1 . min-1 in the control, and 44 micrograms . kg-1 . min-1 in the DOCA group. The cumulative dose of norepinephrine associated with 50% mortality was 160 micrograms/kg in the DOCA high salt group, 370 micrograms/kg in the high salt group, 530 micrograms/kg in the control group, and 600 micrograms/kg in the DOCA group. The blood pressure after sodium loading before norepinephrine infusion was similar in all three groups. The blood pressure response to norepinephrine was not significantly different between the four groups.(ABSTRACT TRUNCATED AT 250 WORDS)

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PubMedDate not supplied

The Canadian exercise technetium 99m-labeled teboroxime single-photon emission computed tomographic study. Canadian Exercise Teboroxime SPECT Study Investigators.

BACKGROUND: 99mTc-labeled teboroxime undergoes rapid washout from the myocardium. For this reason, its use has been favored in conjunction with pharmacologic stress, which enables patient positioning before tracer administration, and multidetector single-photon emission computed tomography (SPECT), which enables rapid acquisition. We evaluated treadmill exercise 99mTc-labeled teboroxime SPECT with single-detector systems for the detection of coronary artery disease. METHODS AND RESULTS: Treadmill exercise 99mTc-labeled teboroxime SPECT was compared with analogous 201Tl-labeled imaging in 108 patients. Teboroxime was injected first during exercise and then at rest. Nine myocardial segments per study were scored with respect to uptake of activity during stress and at rest (teboroxime) or after redistribution (201Tl). Perfusion was defined as normal, reversible, or fixed. Overall agreement of 201Tl versus teboroxime segmental perfusion (normal vs abnormal) was 772/961 (80.3%; chi 2 = 258; p < 0.001; kappa = 0.51) or (normal vs reversible vs fixed) 711/961 (74.0%; chi 2 = 296; p < 0.001; kappa = 0.42). Fifty-six patients also underwent selective coronary angiography. Stenoses greater than 50% of lumenal diameter were drawn on individualized coronary artery diagrams applied to polar plots of scintigraphic segments to compare detection of coronary artery disease. Sensitivity and accuracy of teboroxime were 0.80 and 0.79, respectively, compared with 0.84 and 0.82 for 201Tl (difference not significant). Mean imaging procedure time was 113.6 minutes for teboroxime and 240.5 minutes for 201Tl (p < 0.001). CONCLUSIONS: 99mTc-labeled teboroxime is amenable to simple modifications of routine treadmill exercise SPECT myocardial perfusion imaging protocols with widely available single-detector SPECT systems. This modality provides results similar to those of exercise 201Tl SPECT and is significantly faster.

Adult↗
PubMedDate not supplied

Beneficial effects of streptokinase on left ventricular function after myocardial reoxygenation and reperfusion following global ischemia in the isolated rabbit heart.

To determine the effect of streptokinase on the ischemic myocardium independent of its effects on the occluding thrombus, the isolated rabbit heart, perfused with Krebs-Henseleit solution, was subjected to a 45-min period of ischemia--83% reduction in myocardial (perfusion) flow--plus anoxia (95% N2 and 5% CO2), followed by restoration of perfusion and reoxygenation. Streptokinase, 75 or 150 IU/min, was infused starting 15 min before reperfusion and continuing for 30 min after reperfusion. Compared with the control group, streptokinase was associated during reperfusion with a significant dose-dependent greater restoration or smaller depression of ventricular function, dP/dt, and developed pressure. To determine if streptokinase effects were mediated during the ischemic or reperfusion phase, the high streptokinase dose was administered in either the last 30 min of the ischemia or the first 30 min of reperfusion. The improvement in recovery of left ventricular function was primarily in the group having streptokinase administered only during the ischemic period. Thus, streptokinase affects the ischemic myocardium so that there is an acceleration in the recovery of ventricular function or a reduction of the impairment in ventricular function during myocardial reperfusion.

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