Biomedical subjects
Publications and source records attributed to K L Hsu.
This is a review of a rare case of acute appendicitis secondary to metastatic nasopharyngeal carcinoma (NPC) that had never before been reported in the literature. The clinical presentation did not differ from usual cases of acute appendicitis, but the pathology caused us to re-evaluate the NPC stage of the patient.
To find the best predictors of outcome for patients undergoing intra-aortic balloon counterpulsation (IABP) for cardiogenic shock, we prospectively studied 30 consecutive patients by examining hemodynamic parameters and cardiac lactic acid extraction ratios before the procedure. 1 hour after and then every 6 hours for 3 days. Complete hemodynamic data were obtained from the recordings of Swan-Ganz catheterization. Blood samples were drawn from the peripheral artery, central vein, pulmonary artery wedge position (PAW) and right atrium (RA) to quantify lactic acid levels. The simplified lactic acid extraction ratio was defined as the concentration of lactic acid in RA--the concentration of lactic acid in PAW/the concentration of lactic acid in PAW. The traditional systemic lactic acid production ratio was defined as the concentration of lactic acid in the central vein--the concentration of lactic acid in the peripheral artery/the concentration of lactic acid in the peripheral artery. Of the 30 patients studied, 19 died of cardiogenic shock, (group 1), while the surviving 11 patients formed group 2. The lactic acid extraction ratios at each of the time periods after the procedure were all significantly different, while the differences in the systemic lactic acid production ratio and hemodynamic parameters, including the systemic arterial pressure, cardiac output, cardiac index and PAW pressure, became significant at varying times after IABP. In group 2, the lactic acid extraction ratios 1 hour after IABP and later were all significantly higher than at baseline. This trend was not seen in group 1.(ABSTRACT TRUNCATED AT 250 WORDS)
In a search for features predictive of ventricular arrhythmias in myocardial ischemia, the body surface potential maps of 17 dogs with coronary artery occlusion were studied. Ventricular tachycardia occurred in 9 (53%) of the 17 dogs. Multiple distribution of the abnormal potential minimum was found in 6 (67%) of the 9 dogs with (group A) and none of the 8 dogs without ventricular tachycardia (group B). The difference was statistically significant (p less than 0.01). The abnormal "early reversal" phenomenon of potential distribution was observed in 6 (67%) of group A and 7 (88%) of group B. The difference was not statistically significant (p greater than 0.05). The area of abnormal negative potential was 28.0 +/- 8.5 cm2 for group A and 14.5 +/- 5.5 cm2 for group B (p less than 0.001). The abnormal negative potential lasted for 25.4 +/- 3.5 ms in group A and 10.1 +/- 5.1 ms in group B (p less than 0.001). The abnormally early appearance of potential minimum lasted for 24.2 +/- 5.1 ms in group A and 10.5 +/- 5.4 ms in group B (p less than 0.001). The data suggest that the distribution, area, and duration of the abnormal negative potential of the body surface potential map are useful in the prediction of ventricular tachycardia associated with coronary artery occlusion.
To characterize the intermittency of pre-excitation in patients with Wolff-Parkinson-White syndrome (W-P-W), we studied the ambulatory electrocardiograms (ECGs) of 48 patients (32 men and 16 women with a mean age of 38.5 years) with W-P-W. As documentation, at least one ECG for each patient had been performed during the follow-up period at our clinics. All cardiovascular drugs were discontinued for at least two days before Holter ECG monitoring. Through a careful beat-to-beat analysis of the QRS complex morphology, we were able to classify these patients into three groups: persistent pre-excitation in 26 (54.2%); intermittent pre-excitation in 17 (35.4%); and no pre-excitation in five (10.4%). There was no significant difference in sex, frequency of arrhythmias or mean heart rate among the three groups. Among the 17 showing intermittent pre-excitation, type A W-P-W was more prevalent (12 cases), and the ratio of pre-excitation to normal beats tended to decrease with age. Conduction normalized gradually with an increase in heart rate in 12 patients and suddenly in five other cases. There were two patients who showed a period of 2:1 pre-excitation intermingled with 1:1 pre-excitation and 1:1 normalized beats. These changes occurred with equal frequency both during the daytime and at night. These findings suggest that intermittent pre-excitation is a rather frequent phenomenon in patients with W-P-W. It occurs more frequently in type A patients and in older patients. Therefore, it may be an intermediate phase between manifest and concealed W-P-W.
To study the relationship between the plasma concentration of the atrial natriuretic peptide (ANP) and heart function and to discern the secretion pathway of ANP, we determined the peripheral plasma concentration of ANP in 18 heart patients and the intracardiac concentration of ANP in six heart patients during cardiac catheterization. All plasma was extracted through a Sep-Pak C18 cartridge by acid alcohol. The concentration of ANP was determined by a sensitive and specific radioimmunoassay method. We found that the plasma ANP concentration (pg/mL) in heart patients (ranging from 12 to 139, mean = 36.1 +/- 28.9) was statistically higher than that in normal adults (ranging from 8 to 20, mean = 12.4 +/- 3.3, n = 16; p less than 0.05). The ANP level in heart patients was inversely correlated with the left ventricular ejection fraction (r = -0.53, p less than 0.05) evaluated by radionuclide angiocardiography. The intracardiac level of ANP was 88 +/- 58 at the superior vena cava, 77 +/- 55 at the inferior vena cava, 124 +/- 68 at the right atrium, 98 +/- 64 at the right ventricle, 107 +/- 58 at the pulmonary artery, 98 +/- 52 at the left ventricle, 109 +/- 73 at the aorta and greater than 351 at the coronary sinus. In conclusion, ANP is mainly secreted via the coronary sinus into the atrial cavity. The peripheral plasma ANP concentration is higher in heart patients. It increases as the left ventricular ejection fraction decreases. Therefore, plasma ANP concentration may be a useful indicator for the assessment of cardiac function.
The pathogenic role of enterovirus in patients with idiopathic dilated cardiomyopathy has been determined through a molecular biologic approach. Sensitivity in the detection of viral genomes in tissues varied between conventional nucleic acid hybridization and polymerase chain gene amplification. To improve diagnosis, we developed a strategy for reverse transcription polymerase chain reaction (RT-PCR) to detect viral RNA. We synthesized two sequence-specific oligonucleotides, primer 1 (5'dACCGACGAATACCACTGTTA3') and primer 2 (5'dCCTCCGGCCCCTGAATGCGGCTAAT3'), complementary to the 5' conserved viral genomic fragments. Viral RNA was amplified by double PCR with these two primers and hybridized with a 32-P labeled inter-primer probe (5'dATGAAACCCACAGGCACAAAG3'). Using this strategy, we detected as little as 10(-8) micrograms of coxsackievirus B3 RNA after amplification with RT-PCR, but detected none in the plasma of eight healthy adults. Among 15 patients with idiopathic dilated cardiomyopathy, viral RNA could be detected in one out of 12 plasmas (8%) and three out of four explanted heart tissues (75%). In contrast, no viral RNA could be detected in six samples of myocardial tissue from patients with other heart diseases. The only patient who had viral RNA in his plasma also had viral RNA in his myocardium. Thus, the high incidence of viral RNA in these patients suggests a possible etiologic link between them. Correct selection of specific PCR primers and the application of double PCR can improve chances of diagnosing enteroviral infection.
Atrial natriuretic peptide (ANP) is a cardiac hormone with an important role in fluid, electrolyte and hemodynamic homeostasis. Rat ANP cDNA was cloned from the cDNA library constructed using 1 microgram of atrial mRNA from the heart of Wistar rats. Eight positive clones were isolated with an ANP oligonucleotide probe. One of them with about a 0.8 kb insert was selected for further subcloning and sequencing analysis. The rat ANP cDNA had 813 base pairs with a concensus sequence for transcription initiation, termination and poly A tailing. The deduced amino acid sequence contains a potential glycosylation site and two putative protease cleavage sites. Northern blot analysis showed that the ANP gene was specifically transcribed in the rat atria rather than the ventricles. The results suggest that ANP gene expression is differentially and developmentally controlled.
In an effort to enlarge the clinical application of body surface potential maps (BSPMs), the authors studied the relationship between abnormal ventricular wall motion and BSPMs in 98 consecutive patients with angiographically proven coronary artery disease (CAD). Forty-nine of the patients (50%) had wall motion abnormalities as seen on single-plane left cine ventriculograms. During early ventricular depolarization, normal BSPMs have a potential maximum that is greater than the absolute value of the potential minimum; this reverses in late depolarization such that the absolute value of the potential minimum is the greater. The patients showed a significantly early reversal (p less than 0.001), and 55 (56.1%) had abnormal "early reversal" BSPMs. This abnormal "early reversal" is closely related to abnormal ventricular wall motion. Using it as an indicator of abnormal wall motion, the authors obtained the sensitivity, specificity, positive predictive value, and negative predictive value of the following conditions: LAD lesions, LCX, RCA, LAD and RCA lesions, LAD and LCX, and three-vessel disease, and for all patients. A relatively high sensitivity (85%) and specificity (80%) was found in patients with LAD lesions only or multivessel lesions in addition to LAD lesions.
Body surface potential maps (BSPMs) and the pathology of 32 dogs with coronary artery ligations were analyzed to research the application of BSPMs to acute myocardial infarction (AMI). The group consisted of 18 dogs with left anterior descending coronary artery (LAD) ligations, 8 with right coronary artery (RCA) ligations and 6 with left circumflex coronary artery (LCX) ligations. The abnormal distribution of negative potential and minimal potential were observed in all of the dogs. In dogs with RCA ligations, the abnormal negative potential displayed on the right-superior, right-inferior or right portion of the anterior thorax. In those with LAD ligations, the abnormal potential appeared on the left-superior, left-inferior, middle-superior or middle portion of the anterior thorax. In those with LCX ligations, the abnormal potential showed on the left-superior or left-middle portion of the thorax. A good correlation was observed between the area of myocardial lesion and the extent of abnormal negative potential distribution (r = 0.82, p less than 0.001). A close correlation was also found between the area of myocardial lesion and the duration of abnormal negative potential (r = 0.61, p less than 0.05). This study suggests that BSPMs are useful in the assessment of AMI in terms of diagnosis, location and extent of myocardial infarct.
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)
The distribution of norepinephrine (NE), cyclic AMP (cAMP) and cyclic GMP (cGMP) and the activities of related enzymes in the atrioventricular (A-V) conducting tissue of the bovine heart were examined. The concentration of NE in the atrium was about twice that in the ventricle. In the A-V conducting tissue, the concentration of NE was highest in the atrioventricular node (AVN) and lowest in the false tendon (FT), with intermediate levels in the bundle of His (HIS) and the right and left bundle branches (RLBB). The activity of monoamine oxidase (MAO) in the atrium was about 2.2 times that in the ventricle. In the A-V conducting tissue, the activity of MAO was highest in the HIS and lowest in the FT. The activity of catechol-o-methyltransferase (COMT) in the atrium and ventricle was similar, and that in the HIS was slightly, but not significantly, higher than that in other regions of the A-V conducting tissue. The concentration of cAMP in the ventricle was about twice that in the atrium. In the A-V conducting tissue, the concentration of cAMP was higher in the AVN and FT than in the HIS and RLBB. The distribution of adenylate cyclase (AC) was similar to that of NE. The phosphodiesterase (PDE) activity in the atrium and ventricle was similar. No significant difference was found in the level of PDE activity in different regions of the A-V conducting tissue. The concentration of cGMP was slightly, but not significantly, higher in the A-V conducting tissue than in the atrium or ventricle. In the A-V conducting tissue, the concentration of cGMP was highest in the FT and the concentrations in the HIS, RLBB and AVN were similar. These findings suggest that in the A-V conduction tissue, the regions that have the higher spontaneous pacemaker rates have higher NE content and AC activity, that is sensitivity to NE. Furthermore, the sensitivity for muscarinic cholinergic stimulation is higher in the conducting tissue (especially in the FT) than in the atrium and ventricle.
ATPase activation and superprecipitation of natural actomyosin in the cardiac conduction system (specialized myocardium) and ventricle were compared. The ATPase activity and superprecipitation of natural actomyosin from the specialized myocardium were much lower than those from the ventricle. The sensitivity of natural actomyosin ATPase to calcium was higher in the specialized myocardium than in the ventricle, whereas the maximum activity of the specialized myocardium was lower than that of the ventricle. The Ca2+-desensitized actomyosin of the specialized myocardium presented scarcely any superprecipitation. Addition of the 0-40% ammonium sulfate fraction (mainly containing myosin and actin) of natural actomyosin from the specialized myocardium to ventricular natural actomyosin inhibited superprecipitation of the latter. On the other hand, addition of the 40-60% ammonium sulfate fraction (mainly containing troponins and tropomyosin) of natural actomyosin from the specialized myocardium enhanced superprecipitation of ventricular natural actomyosin. These results suggested that the specialized myocardium contains some factor(s) that inhibits actin-myosin interaction.
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.
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