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Biomedical subjects

Y L Ko

Publications and source records attributed to Y L Ko.

At least 37 records · Page 2Linked to original sources
PubMed1997

Transluminal coronary angioplasty and stenting in a patient with single coronary artery and acute myocardial infarction.

An isolated single coronary artery is a rare congenital anomaly with an incidence of 0.03% to 0.4% and can present additional hazards such as myocardial ischemia, infarction, or sudden death in individuals with atherosclerotic changes in this artery. Herein, we report an acute anterior and inferior wall infarction in a 61-year-old male patient with the right coronary artery arising as a branch of the left coronary artery. Selected coronary angiography showed a 90% stenosis in the left anterior descending artery proximal to the origin of the right coronary artery. The patient underwent successful percutaneous transluminal coronary angioplasty and stenting without compromising the flow to the anomalous right coronary artery. There has been no previous reports of percutaneous transluminal coronary angioplasty and coronary stenting in a patient with this anomaly.

Angioplasty, Balloon, Coronary↗
PubMed1996

Mapping the locus for familial hypertrophic cardiomyopathy to chromosome 11 in a family with a case of apical hypertrophic cardiomyopathy of the Japanese type.

To identify the disease locus of familial hypertrophic cardiomyopathy (FHC) in a Chinese family, a genetic linkage study was performed using polymorphisms from various chromosomal regions. This family has eight affected members, including a case with typical features of apical hypertrophic cardiomyopathy of the Japanese type. The results revealed significant evidence of linkage of polymorphisms on chromosome 11p13-q13 and FHC in this family with a maximal lod score of 3.38 at theta = 0.00. Our data suggest that the locus responsible for FHC in this family maps to chromosome 11 and that the molecular basis of FHC in the case of apical hypertrophic cardiomyopathy of the Japanese type might be similar to that of other affected members in the same family. Further studies are needed to elucidate the whole spectrum of the genetic basis of apical hypertrophic cardiomyopathy of the Japanese type.

Base Sequence↗
PubMed1996

Malignant familial hypertrophic cardiomyopathy in a family with a 453Arg-->Cys mutation in the beta-myosin heavy chain gene: coexistence of sudden death and end-stage heart failure.

Recent genotype-phenotype correlation studies in familial hypertrophic cardiomyopathy (FHC) have revealed that some mutations in the beta- myosin heavy chain (BMHC) gene may be associated with a high incidence of sudden death and a poor prognosis. Coexistence of sudden death and end-stage heart failure in several families with FHC has recently being reported; however, the genetic basis of such families has not been clearly demonstrated. A three-generation Chinese familial hypertrophic cardiomyopathy (FHC) family (family HLI) with two cases of end-stage heart failure and three cases of sudden death was analyzed. The average age of death in the affected members in this family was 34 years old. Genetic linkage analysis using polymorphisms in the (alpha- and beta-myosin heavy chain genes revealed that FHC in this family is significantly linked to the BMHC gene without recombinations. Single-strand conformation polymorphism analysis of exons 8, 9 and 13 to 23 in the BMHC gene showed a polymorphic band on exon 14 that is in complete linkage with the disease status in this family. DNA sequencing analysis in the affected members revealed an 453Arg-->Cys mutation in the BMHC gene. To our knowledge this is the first reported mutation of FHC in Chinese. Our data suggest that the 453Arg-->Cys mutation is associated with a malignant clinical course in FHC due not only to sudden death but also to end-stage heart failure.

Adolescent↗
PubMed1996

The G1691A mutation of the coagulation factor V gene (factor V Leiden) is rare in Chinese: an analysis of 618 individuals.

To understand the allele frequency of the G1691A mutation of the coagulation factor V gene (factor V Leiden) in Chinese, 618 Chinese individuals, including 54 cases with venous thrombosis, were analyzed. Only one case in the control group was heterozygous for the 1691G allele and the 1691A allele. Our data suggest that the factor V Leiden is rare in Chinese.

Alleles↗
PubMed1996

Metastatic colonic carcinoma with intracavitary right ventricular outflow tract obstruction and cardiac tamponade: a case report.

Intracavitary metastasis causing right ventricular outflow tract (RVOT) obstruction is very rare. Combination of cardiac tamponade with RVOT obstruction due to intracavitary metastasis has never been reported in the literature. Herein, we report a case of colonic carcinoma with sudden onset of severe dyspnea. Echocardiography detected cardiac tamponade as well as a huge intracavitary mass obstructing the RVOT. Pericardiocentesis and surgical resection of the right ventricular mass were performed but the patient died during operation. Thus, the combination of intracavitary RVOT obstruction and cardiac tamponade in a patient with carcinoma suggests extensive myocardial and pericardial involvement with a poor prognosis.

Cardiac Tamponade↗
PubMed1995

Transesophageal echocardiographic assessment of mitral valve position and pulmonary venous flow during cardiopulmonary resuscitation in humans.

BACKGROUND: The mechanisms of blood flow during closed-chest cardiopulmonary resuscitation (CPR) in humans have been debated since the technique was first described in 1960. Two competing models, the cardiac pump theory and the thoracic pump theory, have been proposed, and some investigators have used mitral valve position during the downstroke of chest compression to distinguish between them. Previous studies using either transthoracic or transesophageal echocardiography have yielded conflicting results, and there have been few, if any, hemodynamic or echocardiographic studies on pulmonary venous flow (PVF) during CPR. METHODS AND RESULTS: In this study, transesophageal two-dimensional and pulsed Doppler echocardiography were used to study mitral valve position and flow, together with PVF, in 20 adult patients undergoing manual CPR. In the 17 patients who could be analyzed, the mitral valve closed in 5 patients (group 1) during chest compression but stayed open or opened further in the remaining 12 patients (group 2). Peak forward mitral flow occurred during the release phase in group 1 but during the compression phase in group 2. During chest compression, PVF occurred in the forward direction (from the pulmonary vein to the left atrium) in 8 of the group 2 patients (group 2a) and in the backward direction (from the left atrium to the pulmonary vein) in all group 1 patients and the remaining 4 patients in group 2 (group 2b). The downtime (time from collapse to CPR) was significantly shorter (P < .05) for those in group 1 (7.0 +/- 4.4 minutes) than in groups 2a (19.8 +/- 7.7 minutes) and 2b (17.8 +/- 6.8 minutes). CONCLUSIONS: Transesophageal echocardiography performed during manual CPR in humans disclosed three different patterns of mitral valve position and PVF during chest compression. The presence of an opened mitral valve with forward mitral flow and backward pulmonary venous flow during chest compression in a small number of subjects underscores this heterogeneity in blood flow and suggests the possible existence of a "left atrium pump" in addition to the currently known "left ventricle pump" and "chest pump" mechanisms.

Adult↗
PubMed1995

Reappraisal of quantitative evaluation of pulmonary regurgitation and estimation of pulmonary artery pressure by continuous wave Doppler echocardiography.

This study assessed the usefulness of continuous wave Doppler echocardiography and color flow mapping in evaluating pulmonary regurgitation (PR) and estimating pulmonary artery (PA) pressure. Forty-three patients were examined, and high quality Doppler spectral recordings of PR were obtained in 32. All patients underwent cardiac catheterization, and simultaneous PA and right ventricular (RV) pressures were recorded in 17. Four Doppler regurgitant flow velocity patterns were observed: pandiastolic plateau, biphasic, peak and plateau, and early diastolic triangular types. The peak diastolic and end-diastolic PA-to-RV pressure gradients derived from the Doppler flow profiles correlated well with the catheter measurements (r = 0.95 and r = 0.95, respectively). As PA pressure increased, the PR flow velocity became higher; a linear relationship between either systolic or mean PA pressure and Doppler-derived peak diastolic pressure gradient was noted (r = 0.90 and 0.94, respectively). Based on peak diastolic gradients of < 15, 15-30 or > 30 mm Hg, patients could be separated as those with mild, moderate or severe pulmonary hypertension, respectively (p < 0.05). A correlation was also observed between PA diastolic pressure and Doppler-derived end-diastolic pressure gradient (r = 0.91). Moreover, the Doppler velocity decay slope of PR closely correlated with that derived from the catheter method (r = 0.98). The decay slope tended to be steeper with the increment in regurgitant jet area and length obtained from color flow mapping. In conclusion, continuous wave Doppler evaluation of PR is a useful means for noninvasive estimation of PA pressure, and the Doppler velocity decay slope seems to reflect the severity of PR.

Adolescent↗
PubMed1995

Apical segmental dysfunction in hypertrophic cardiomyopathy: progression into end-stage heart failure with sudden cardiac death.

Apical segmental dysfunction is an unusual finding in hypertrophic cardiomyopathy (HCM). It is characterized by a poor clinical course and a high incidence of malignant ventricular tachyarrhythmias. Long-term prognosis of patients with HCM and apical segmental dysfunction is still unclear. We report 2 cases of apical segmental dysfunction in HCM in whom progressive apical dilatation and congestive heart failure developed. Both patients died suddenly, and intractable ventricular tachyarrhythmias were documented in 1 case during resuscitation. This report provides further evidence that apical segmental dysfunction might predict a subgroup of patients with HCM who are likely to develop end-stage heart failure and are at high risk of sudden cardiac death.

Adolescent↗
PubMed1995

Left atrial spontaneous echo contrast in patients with rheumatic mitral valve disease in sinus rhythm. Implication of an altered left atrial appendage function in its formation.

Thirty-nine patients who had rheumatic mitral valve disease in sinus rhythm were studied to compare echocardiographic and hemodynamic characteristics between those with and without left atrial (LA) spontaneous echo contrast. Patients were divided into two groups according to the presence (group 1, n = 17) or absence (group 2, n = 22) of the echo contrast. Transthoracic echocardiography and transesophageal echocardiography were performed in all patients within 1 week of cardiac catheterization study. Group 1 patients (5 men and 12 women; mean age, 47.7 +/- 13.1 years) showed smaller mitral valve area, greater transmitral valve pressure gradient, and absence of moderate to severe mitral regurgitation compared with group 2 patients (7 men and 15 women; mean age, 47.8 +/- 14.3 years). There was no significant difference in LA dimension, left ventricular end-systolic and end-diastolic dimensions, or in left ventricular ejection fraction between the two groups of patients. Left atrial appendage function was studied with Doppler in 26 patients. Patients (n = 10) with LA spontaneous echo contrast had significantly lower LA appendage ejection fraction (20.34 +/- 10.76% vs 34.16 +/- 13.13%; p < 0.05) and lower LA appendage peak emptying velocity (0.17 +/- 0.09 m/s vs 0.27 +/- 0.12 m/s; p < 0.05) than those (n = 16) without echo contrast. It is concluded that obstruction to mitral flow and altered LA appendage contractile function, not the LA size, are likely to be more important factors for the development of LA and LA appendage spontaneous echo contrast in patients with rheumatic mitral valve disease (predominant mitral stenosis) who are in sinus rhythm. These findings further substantiate that blood stasis in the LA cavity and the LA appendage is the mechanism fundamental to the formation of such spontaneous echo contrast.

Adult↗
PubMed1995

Swyer-James syndrome associated with Noonan syndrome: report of a case.

A 28-year-old man with Noonan syndrome associated with unilateral hyperlucent lung is reported. He had the typical craniofacial appearance and short stature of Noonan syndrome; he had mild mental retardation, atrophic testis, mild funnel chest and kyphosis. cardiovascular abnormalities included asymmetric hypertrophic cardiomyopathy and a significantly different caliber of the left and right pulmonary arteries. The unilateral hyperlucent lung was shown to result from acquired nondestructive emphysema caused by nonvalvular obstruction of the bronchi (Swyer-James syndrome or Macleod's syndrome). To the authors' knowledge, this is the first reported case of Noonan syndrome associated with Swyer-James syndrome.

Adult↗
PubMed1994

Fracture of a perfusion balloon catheter during coronary angioplasty.

In a 74-year-old patient with increasing angina, an attempt was made to dilate an ostial stenosis in the first diagonal artery. The initial attempt with a long balloon catheter was unsuccessful. Because of chest pain associated with hypotension during balloon inflations, a second attempt with a perfusion balloon catheter resulted in fracture of this catheter's tip (14 mm long) in the artery. Bypass graft surgery was performed and the retained fragment was easily removed by arteriotomy. The patient made an uneventful recovery.

Aged↗
PubMed1994

No evidence for linkage of long QT syndrome and chromosome 11p15.5 markers in a Chinese family: evidence for genetic heterogeneity.

Recently the defective gene locus in seven Caucasian families with the Romano-Ward form of long QT syndrome (LQT) has been mapped to chromosome 11p. To understand the molecular basis of LQT in Chinese, a three-generation family was investigated. Fourteen family members were studied and five individuals were diagnosed to be affected, according to electrocardiographic criteria. Two genomic DNA probes (c-Ha-ras-3'-HVR and insulin-5'-HVR) and one tetranucleotide repeat polymorphism (THZ) derived from chromosome 11p15.5 loci and previously demonstrated to be closely linked to LQT were used as probes to analyze this family. A lod score of less than -2 was noted for all three polymorphisms. Our data show that there was no evidence of linkage between these three loci and the gene for LQT in this studied family. We believe that this result provides additional evidence for genetic heterogeneity of LQT.

Adolescent↗
PubMed1994

Significance of left atrial spontaneous echo contrast in rheumatic mitral valve disease as a predictor of systemic arterial embolization: a transesophageal echocardiographic study.

The association between left atrial spontaneous echo contrast (SEC) and a history of systemic arterial embolization was evaluated in 359 consecutive patients with rheumatic mitral valve disease during a 3-year period. All patients underwent transesophageal echocardiographic (TEE) and cardiac catheterization studies. Of these, 207 patients had predominant mitral stenosis, 55 had significant mitral regurgitation, and the remaining 97 with xenograft mitral valve replacement developed valvular dysfunction (32 resulted in predominant mitral stenosis and 65 in significant mitral regurgitation). Left atrial SEC was detected in 108 patients (group A) and was absent in 251 (group B). Group A patients showed a higher frequency of left atrial thrombi or history of previous embolization than those in group B (59.3% vs 7.2%; p < 0.001). Group A patients also had a higher frequency of recent (< or = 1 week before TEE study) and remote (> 1 week before TEE study) embolization than did group B patients (recent: 19.4% vs 2.8% [p < 0.001]; remote: 13.0% vs 4.0% [p < 0.001]). Multivariate analysis showed that left atrial SEC (p = 0.01) was the only independent predictor of systemic arterial embolization. It is concluded that patients with left atrial SEC had a significantly higher risk for thromboembolism, and TEE is a useful modality to identify this subset of patients with rheumatic mitral valve disease.

Adult↗
PubMed1994

Clinical implications of left atrial appendage function: its influence on thrombus formation.

This study evaluated the relation between left atrial appendage (LAA) function and LAA spontaneous echo contrast (SEC) or thrombus formation. Seventy-five patients (45 men and 30 women, aged 14-79 years) referred for transesophageal echocardiography (TEE) were examined for LAA area (maximal and minimal), LAA ejection fraction ([LAA maximal area--LAA minimal area]/LAA maximal area), LAA peak emptying velocity, and these patients were classified into three groups by different LAA blood flow patterns: Group 1--25 patients with well-defined biphasic configuration of LAA flow; Group 2--28 patients with multiphasic configuration of LAA flow; Group 3--22 patients with very low LAA blood flow and, sometimes, barely detected Doppler signal. All the 25 patients in Group 1 had a sinus rhythm during TEE study, while the other 50 patients in Groups 2 and 3 were in atrial fibrillation. The patients in Group 3 had the lowest LAA ejection fraction and the lowest peak emptying velocity of these three groups. LAA SEC was present in five of 28 patients in Group 2 and 14 of 22 patients in Group 3, but in none of 25 patients in Group 1 (P < 0.001). LAA thrombus was present in one of 25 patients in Group 1, two of 28 patients in Group 2, and seven of 22 patients in Group 3 (P < 0.05). In conclusion, this study found that patients with poor LAA function, which was represented by lower LAA ejection fraction and lower peak emptying velocity, had higher incidence of LAA SEC or thrombus formation.

Adolescent↗
PubMed1994

Left atrial appendage function determined by transesophageal echocardiography in patients with rheumatic mitral valve disease.

Left atrial thrombi have been considered to be the major source of systemic arterial embolization in patients with rheumatic mitral valve disease. Almost half of the left atrial thrombi are found in the left atrial appendage (LAA). To investigate LAA size and LAA contractile function in patients with rheumatic mitral valve disease, transesophageal echocardiographic and Doppler studies were performed in 61 patients. Among them, 46 patients were in atrial fibrillation (group 1), while the other 15 were in sinus rhythm (group 2). Thirty-six patients with nonrheumatic atrial fibrillation were chosen as control to group 1. Another 22 patients with various cardiovascular diseases and sinus rhythm served as control to group 2. When compared to the patients with nonrheumatic atrial fibrillation (control group), group 1 patients tended to have a larger LAA maximal area (9.7 +/- 5.2 vs. 5.9 +/- 2.8 cm2; p < 0.001). LAA ejection fraction and LAA peak emptying velocity were also lower. A significantly higher incidence of LAA spontaneous echo contrast (SEC) and thrombus formation was also found in these patients. Group 2 patients were also found to have a larger LAA maximal area when compared to the control group (8.8 +/- 3.7 vs. 5.2 +/- 3.0 cm2; p < 0.001). LAA ejection fraction and LAA peak emptying velocity were lower in this group, too. A higher incidence of LAA SEC formation was found in these patients with rheumatic mitral valve disease (4/15 vs. 0/22; p = 0.021). There was no significant difference, however, in LAA thrombus formation between group 2 and its control group (1/15 vs. 1/22; p = NS).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Change in left ventricular diastolic filling patterns in patients with supraventricular tachycardia treated by radiofrequency ablation: a Doppler echocardiographic study.

To evaluate changes in left ventricular diastolic filling patterns resulting from radiofrequency ablation for supraventricular tachycardia (SVT), 44 patients with SVT undergoing radiofrequency ablation (study group), and 16 patients with SVT undergoing electrophysiologic study without ablation (control group) were studied by pulsed Doppler echocardiography. Peak early diastolic filling velocity (E), peak atrial filling velocity (A), and an E/A ratio were obtained from the transmitral flow velocity pattern before and 24-48 h after ablation or electrophysiologic study. In the study group, E and E/A ratio decreased from 67 +/- 16 and 1.26 +/- 0.42 to 61 +/- 16 cm/s and 1.09 +/- 0.39 (p < 0.001), respectively. In the control group, only E/A ratio decreased from 1.40 +/- 0.47 to 1.26 +/- 0.44 (p < 0.001). Heart rate increased from 71 +/- 10 to 80 +/- 10 beats/min (p < 0.001) in the study group and from 67 +/- 8 to 72 +/- 10 beats/min (p < 0.05) in the control group. E and E/A ratio decreased significantly from 73 +/- 17 and 1.35 +/- 0.49 to 60 +/- 18 cm/s and 0.96 +/- 0.40 (p < 0.001) in patients with heart rate change of > 20% after ablation. E, A, and E/A ratio did not change significantly in patients with heart rate change of < 10% and of between 10 and 20% after ablation. Blood pressure and left ventricular ejection fraction did not change in either the study or control groups. It was concluded that left ventricular ejection fraction and Doppler diastolic filling patterns are unaffected by radiofrequency ablation.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Usefulness of pulmonary venous flow pattern and maximal mosaic jet area detected by transesophageal echocardiography in assessing the severity of mitral regurgitation.

Pulmonary venous flow pattern detected by transesophageal echocardiography (TEE) has been reported to be a good marker of mitral regurgitation (MR) severity. In 89 patients with MR detected by TEE, both pulmonary venous flow pattern and maximal mosaic jet area were recorded for evaluating the severity of MR. Cardiac catheterization was performed in all patients for grading the severity of MR. Systolic reversed flow in pulmonary veins was a good marker for angiographic grade 3 or 4 MR with a sensitivity of 97% (33 of 34) and specificity of 95% (52 of 55). Maximal mosaic jet area had a good correlation with the grading of MR (r = 0.79). When a maximal mosaic jet area of > 6 cm2 was used to detect grade 3 or 4 MR, the sensitivity and specificity were lower than those of the systolic reversed flow (sensitivity 82 vs 97%, p = 0.073; specificity 80 vs 95%, p = 0.013). The accuracy of systolic reversed flow was not influenced by the cardiac rhythm or jet eccentricity. However, the sensitivity of maximal mosaic jet area was lower in patients with an eccentric jet than in patients with a central jet (67 vs 95%, p = 0.046). In conclusion, systolic reversed flow in pulmonary veins detected by TEE is better than the maximal mosaic jet area in detecting grade 3 or 4 MR, especially in patients with eccentric jet.

Adolescent↗