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Biomedical subjects

H M Lo

Publications and source records attributed to H M Lo.

At least 73 records · Page 4Linked to original sources
PubMed1990

Low oxygenation index and pulmonary artery hypertension in predicting early death from adult respiratory distress syndrome (ARDS).

Hemodynamic and respiratory parameters were continuously monitored in 45 septic shock patients, 15 of whom developed adult respiratory distress syndrome (ARDS). Low oxygenation index (OI = PaO2/FIO2), pulmonary artery hypertension (high mean pulmonary artery pressure, MPAP) and elevated pulmonary vascular resistance (PVR) were observed in all ARDS, as well as in non-ARDS septic patients, as a baseline. These same pulmonary factors were compared between those who survived and those who died during the first few days (early fatalities) in both the ARDS group (5 patients) and the non-ARDS group (8 patients). The results showed that the early fatalities in the ARDS group had a significantly lower (p less than 0.001) OI than the survivors, as well as a lower MPAP (p less than 0.01). In the non-ARDS group, the MPAP of the early fatalities was significantly lower (p less than 0.01) than that of survivors, but their OI was not significantly lower. PVR, when compared between groups (ARDS versus non-ARDS) or between subgroups within each group, was elevated concurrently with the elevation of MPAP. It is concluded that patients with septic shock and ARDS who show a severely depressed OI and a modestly elevated MPAP and PVR during the first few days can be predicted to have a poor outcome.

Adult↗
PubMed1990

Hemodynamic significance of vectorcardiographic pattern in patients with mitral stenosis.

Vectorcardiographic (VCG) studies were conducted in 71 patients with pure mitral stenosis (MS) documented by clinical findings, echocardiograms and cardiac catheterization. Among them, 31 were males and 40 females, with ages ranging from 20 to 58 (mean age 36.3) years. The Frank lead system was adopted for the VCG study. By VCG, 67 patients (94.4%) showed right ventricular hypertrophy (RVH), among whom 15 (21.2%) were type A, 30 (42.3%) type B and 22 (31.0%) type C. Forty-five patients (63.4%) were in sinus rhythm (NSR), while the remaining 26 (36.6%) were in atrial fibrillation (AF). Patients with type A RVH had a significantly higher pulmonary wedge (PAW) and main pulmonary arterial (MPA) pressures than those with type B or C. Patients with type C had a higher mean MPA pressure (39.0 +/- 11.3 mmHg) than those with type B (32.3 +/- 10.1 mmHg) (p less than 0.05). Among the 3 types of RVH, the mean right atrial (RA) pressures were similar (p greater than 0.05). Patients with AF had a lower mean MPA pressure, but a higher RA pressure than those with NSR (p less than 0.05). The maximal anterior force and maximal rightward force at the horizontal plane were significantly correlated with the mean MPA pressure (r = 0.54 and 0.49, respectively, both p less than 0.01), but they did not correlated well with the PAW and RA pressures (p greater than 0.05). We conclude that in patients with MS, as pulmonary hypertension progresses, VCG seems to begin with type B RVH, then emerges into type C and finally becomes type A.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

[Cavernous hemangioma of the heart: report of a case].

Cavernous hemangioma of the heart is a very rare disease. A 57-year-old male patient was admitted due to frequent onset of dull chest pain, which had been occurring for about 1 year. The pain was not related to exercise and was not relieved with nitroglycerin. On echocardiographic examination, a tumor was shown in the outflow tract of the right ventricle and was confirmed with computer tomography. He underwent open heart surgery for resection of the tumor. After a median sternotomy and opening of the pericardial cavity, a reddish-brown-colored tumor, 3 cm in diameter, was found protruding from the epicardial layer of the right ventricular outflow tract. The tumor involved all layers of the ventricle and could be resected only with the help of the cardiopulmonary bypass technique. The defect in the right ventricle was repaired with a woven dacron patch. The patient recovered without incident after the operation, and experienced no chest pain during 7 months of follow-up. Histology showed it to be a cavernous hemangioma.

Heart Neoplasms↗
PubMed1989

Vectorcardiograms in normal adult rats: with special reference to its pattern different from man.

To understand the vectorcardiographic (VCG) patterns in rats, we studied 50 adult male Long-Evans rats weighing 250-350g. Under anesthesia with pentothal, the rat was fixed to woodplate in a supine position with extremities extended. Surface electrocardiograms (ECG) and VCG of Frank lead system were then recorded in all rats. All variables of ECG and VCG were measured and compared with those of humans to determine the main difference. We found that rats have prominent anterior force of QRS complex and large ST vector in both ECG and VCG as compared to those of humans. The prominent anterior force of QRS complex may be due to different body shape between rat and human chests, and the large ST vector is probably related to early ventricular repolarization in rats. These findings should be considered in any experimental condition involving the ECG and VCG in rats.

Animals↗
PubMed1989

Time course of the ventricular arrhythmias following coronary reperfusion in dogs.

The time course of ventricular arrhythmia following reperfusion was investigated in 12 dogs undergoing a 2-hour coronary artery occlusion followed by reperfusion. At days 1, 3 and 7 following coronary reperfusion, the cardiac rhythm was monitored with a 24-hour Holter electrocardiographic recorder. Six dogs with sham operations were also studied with Holter monitoring at the same time periods as a control group. This showed that, following coronary reperfusion, all 12 dogs (group A) developed frequent premature ventricular complexes (PVCs) at day 1, with a total count (beats per hour, bph) of 1,806 +/- 390 (mean +/- SD). The PVC count decreased to 298 +/- 96 at day 3 (p less than 0.001) and 0.4 +/- 0.1 at day 7 (p less than 0.001). The incidence of spontaneous sustained ventricular tachycardia (VT) at day 1 was 100%; 1 of them deteriorated to ventricular fibrillation (VF). At day 3, 9 of the remaining 11 dogs (82%) had recurrent VTs (p greater than 0.05 vs day 1) which were of shorter duration and a slower rate. One of the 11 dogs died at day 5 and the remaining 10 dogs survived to day 7, with all the VTs subsiding (p less than 0.001 vs day 1 or 3). In the control group, only isolated PVCs were observed at day 1 (7 +/- 3 bph, p less than 0.001 vs group A) and no spontaneous VT or VF was noted. We conclude that spontaneous ventricular arrhythmias were observed in all dogs with coronary reperfusion following a 2-hour coronary artery occlusion and the arrhythmias could subside in 1 week of those survived. Only rarely did VT deteriorate to VF.

Animals↗
PubMed1985

Effect of intracoronary verapamil on infarct size in the ischemic, reperfused canine heart: critical importance of the timing of treatment.

In an effort to determine whether the beneficial effect of calcium blocking drugs occurs only during ischemia or during reperfusion as well, anesthetized dogs were subjected to 3 hours of occlusion of the left anterior descending coronary artery followed by 3 hours of reperfusion. In protocol A, intracoronary verapamil (0.01 mg/kg/min) was begun 90 minutes after coronary occlusion and continued for 1 hour into the reperfusion phase (n = 6) while a control group received an infusion of saline solution (n = 6). In vivo area at risk determined by dye injection was 29 +/- 3% of the left ventricle (+/- standard error of the mean) in the control group and 30 +/- 3% in the verapamil group (difference not significant [NS]), whereas the area of necrosis determined by triphenyltetrazolium staining and expressed as a percent of area at risk was smaller in the verapamil group (29 +/- 8%) than in the control group (57 +/- 8%, p less than 0.05). In protocol B, verapamil infusion into the left anterior descending coronary was begun 5 minutes before blood reperfusion and continued throughout the 3-hour reperfusion phase. Area at risk was similar in both groups (control, 25 +/- 1%, n = 8; verapamil, 28 +/- 2%, n = 8, NS); area of necrosis expressed as a percentage of area at risk was 49 +/- 6% in the control group and 45 +/- 10% in the verapamil group (NS). Therefore, calcium blockade of ischemic myocytes delays death and enhances salvage produced by reperfusion. However, calcium blockade begun after prolonged coronary occlusion does not enhance reperfusion-induced myocardial salvage.

Animals↗
PubMed1985

Alterations in the distribution of high-energy phosphates during ischemia in a canine model of reperfusion-induced ventricular fibrillation.

High-energy phosphate metabolites of the canine heart were analyzed before coronary artery occlusion and after 15 minutes of ischemia, and the results were then correlated with the occurrence of ventricular fibrillation upon reperfusion (RVF). Animals which developed VF upon reperfusion after 15 minutes of ischemia had lower levels of creatine phosphate and endocardial adenosine triphosphate (ATP), and increased accumulation of the catabolites of ATP metabolism, inosine and hypoxanthine. Animals which developed RVF also had lower levels of regional myocardial blood flow in the center of the ischemic zone during the period of coronary occlusion. Occluded bed size was the same in dogs which did and did not develop RVF. These data suggest that VF upon reflow is associated with more severe ischemia and an increase in high-energy phosphate catabolism during the period of ischemia.

Adenine Nucleotides↗