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Biomedical subjects

C W Chiang

Publications and source records attributed to C W Chiang.

At least 19 recordsLinked to original sources
PubMed1996

Video-assisted mitral valve operations.

BACKGROUND: Video-assisted endoscopy has been applied frequently in the management of a variety of surgical diseases. However, it has rarely been applied in mitral valve surgery. METHODS: We report 2 patients who received emergency operations for thrombosis of a mitral prosthesis (patient 1, a 68-year-old man) and acute mitral regurgitation due to rupture of anterior chordae (patient 2, a 75-year-old woman). They both had severe congestive heart failure. Cardiogenic shock was noted in patient 2. The mitral valve was approached through a right anterior minithoracotomy with the aid of an endoscope by means of projected images on the video monitor under femorofemoral cardiopulmonary bypass. The aorta was not cross-clamped, and the myocardium was protected by continuous coronary perfusion with hypothermic fibrillatory arrest. The left atrium was entered posterior to the interatrial groove. Thrombectomy and mitral valve repair were performed successfully. RESULTS: The duration of extracorporeal circulation was 204 and 147 minutes, respectively. Both patients recovered from the operation rapidly with uneventful postoperative courses. CONCLUSIONS: Our preliminary results suggest that video-assisted endoscopic cardiac surgery is technically feasible and could be performed in the milieu of open heart surgery.

Aged↗
PubMed1995

[Angioplasty for subclavian artery stenosis: report of two cases].

We present our experience of percutaneous transluminal angioplasty (PTA) in the treatment of subclavian artery stenosis in two patients. One patient was a 66-year-old asymptomatic man. His left arm systolic blood pressure was 40 mmHg lower than that of his right arm. He had irregular segmental stenotic lesions (50% to 80%) at the proximal portion of the left subclavian artery. PTA was attempted via the left brachial artery. After the procedure, the stenotic lesion seemed totally dilated and his left arm systolic blood pressure was 8 mmHg lower than that of his right arm. Restenosis of the left subclavian artery was noted four months after the procedure. The second patient was a 51-year-old man with symptoms of intermittent dizziness, nausea and vertigo. His left arm systolic blood pressure was 30 mmHg lower than that of his right arm. He had 43% diameter stenotic lesion at the proximal portion of the left subclavian artery. PTA was attempted via right femoral artery. After the procedure, the stenotic lesion seemed markedly dilated and his left arm systolic blood pressure was 14 mmHg lower than that of his right arm. He is well three years post-procedure without evidence of restenosis.

Aged↗
PubMed1994

Long-term results of polytetrafluoroethylene mitral annuloplasty.

Prosthetic rings are customarily used for mitral annuloplasty to plicate and reinforce the annulus and keep the annulus from further dilating. From July 1984 to March 1992, mitral annular plication using polytetrafluoroethylene (PTFE) graft material was performed on 73 patients (age range, 15 to 69 years; mean, 35.7 years) with mitral regurgitation. The cause of the mitral regurgitation was rheumatic in 50.7% and degenerative in 36.9% of the patients. After other repair procedures on the mitral valve apparatus had been performed, a PTFE graft (3 mm) was tailored to the length of the free edge of the anterior leaflet and then inserted at the posterior part of the mitral annulus between the commissures. The operative mortality was 2.7%. Follow-up ranged from 0.7 to 8.5 years (mean, 5.6 years). Postoperative echocardiography confirmed that 94.2% of the survivors had either no or only mild mitral regurgitation with a large mitral valve area (2.7 +/- 0.3 cm2) and almost no pressure gradient across the mitral valve or left ventricular outflow tract. Two patients successfully underwent redo PTFE mitral annuloplasty. Two patients died, one 15 and the other 20 months later, due to myocardial failure, with no mitral regurgitation. The event-free survival rate was 90% +/- 4% at 8 years. We conclude that PTFE mitral annuloplasty is an effective procedure that yields good long-term results.

Adolescent↗
PubMed1994

Comparisons between female and male patients with mitral stenosis.

OBJECTIVE: To compare Doppler, echocardiographic, and clinical variables in female and male patients with mitral stenosis. DESIGN: Observational study in consecutive patients with mitral stenosis of cross sectional and Doppler echocardiographic and clinical variables and a retrospective search for a history of systemic embolism. SETTING: A medical centre with 3000 beds, serving both urban and rural populations. PATIENTS: 500 consecutive patients with an echocardiographic mitral valve area of 2 cm2 or less. 331 (66.2%) were female and 169 (33.8%) male (mean (SD) ages of 49 (13) and 48 (14) respectively). MAIN OUTCOME MEASURES: Mitral valve areas by echocardiographic planimetry and Doppler pressure half-time method, peak early diastolic mitral velocity and pressure gradient, echocardiographic score of mitral valve, left atrial end systolic diameter, frequency of left atrial thrombus and smoky echoes as well as various valve lesions detected with Doppler and echocardiography, cardiac rhythm, symptomatic functional class of heart failure, and history of systemic embolism. RESULTS: The prevalence of significant tricuspid (22% v 9%, P < 0.001) and pulmonary regurgitation (5% v 1%, P = 0.018) was higher in the female patients than in the male patients. Female patients also had a higher peak regurgitant velocity (3.2 (0.7) v 2.9 (0.7) m/s, P = 0.007) and pressure gradient (41 (21) v 36 (19) mm Hg, P = 0.010) across the tricuspid valve. However, the male patients had a higher echocardiographic score (9.7 (2.4) v 7.0 (2.3), P < 0.001) and a smaller Doppler-derived mitral valve area (0.9 (0.4) v 1.0 (0.4) cm2, P = 0.027). There were no differences between the female and the male patients in mitral valve area measured by planimetry, peak early diastolic mitral velocity and pressure gradient, and left atrial end systolic diameter or in the prevalence of atrial fibrillation, left atrial thrombus, left atrial smoky echoes, significant aortic stenosis, aortic regurgitation, or heart failure of New York Heart Association class III or IV. CONCLUSIONS: Female patients not only had a higher prevalence of mitral stenosis but also had a higher prevalence of associated tricuspid and pulmonary regurgitation along with a higher velocity and gradient of tricuspid regurgitation. The echocardiographic score was higher in male patients, however. These findings suggest that the pathophysiology of mitral stenosis is different in the two sexes and that gender should be taken into account when therapeutic strategies are formulated.

Echocardiography↗
PubMed1994

Noninvasive predictors of systemic embolism in mitral stenosis. An echocardiographic and clinical study of 500 patients.

Few predictors of systemic embolism in patients with mitral stenosis have been identified by noninvasive methods. This study used the most powerful noninvasive diagnostic tool, transthoracic echocardiography, as well as other noninvasive clinical information to look for predictors. Five hundred consecutive patients with a mitral valve area of 2 cm2 or less were studied. They were divided into two groups: group 1 consisted of 143 patients with a history of systemic embolism and group 2 consisted of 357 patients with no history of systemic embolism. Using a stepwise logistic regression on a random subsample of 400 patients, 4 independent predictors were found: the presence of atrial fibrillation (p = 0.003, relative risk [RR] = 2.3, 95% CI = 1.3, 4.2), the absence of significant tricuspid regurgitation (p = 0.008, RR = 2.5, 95% CI = 1.3, 4.9), the absence of aortic regurgitation (p = 0.022, RR = 2.2, 95% CI = 1.1, 4.2), and the presence of left atrial smoky echoes (p = 0.039, RR = 1.7, 95% CI = 1.1, 3.0). When the above model, together with significant interaction terms, was applied to the remaining 100 patients, both the Hosmer-Lemeshow and Brown goodness-of-fit statistics were not significant (p = 0.888 and p = 0.248, respectively), indicating that the fit was adequate and the model was validated. Thus, important noninvasive predictors of systemic embolism in patients with mitral stenosis can easily be obtained. Subgroups of patients with high risk of systemic embolism can be identified. This may refine our therapeutic strategies to prevent the catastrophe of systemic embolism.

Adolescent↗
PubMed1994

Echocardiographic study of Ebstein's anomaly.

This report analyze the M-mode, two-dimensional (2-D) Doppler and contrast echocardiographic features of 8 patients with Ebstein's anomaly. The diagnosis was confirmed by cardiac catheterization in all cases. M-mode echocardiograms showed: dilated right ventricular cavity (29-59 mm) in 7 patients (88%), abnormal septal motion in 6 patients (75%), delayed closure of tricuspid valve in 4 patients (50%), increased excursion of anterior tricuspid leaflet (20-32 mm) in 6 patients (75%). Two-dimensional echocardiogram revealed: apical displacement of septal tricuspid leaflet (10-43 mm) in all cases (100%), elongated anterior tricuspid leaflet with whip-like motion in 7 patients (88%), tethering of septal tricuspid leaflet in 1 case (13%). The Doppler studies revealed tricuspid regurgitation in 4 of the 5 cases studied (80%) and atrial septal defect flow pattern in all 5 cases studied (100%). Contrast study showed right to left shunt through the atrial septal defect in all 5 cases studied (100%). We conclude that echocardiography is a useful diagnostic tool in detecting Ebstein's anomaly.

Adolescent↗
PubMed1993

Arrhythmogenicity of catheter ablation in supraventricular tachycardia.

To evaluate arrhythmogenicity in patients who receive a modified direct-current (DC) shock ablation (distal pair of electrodes connected in common as the cathode) or radiofrequency (RF) ablation of supraventricular tachycardia, a prospective study was performed with signal-averaged ECG, 24-hour Holter monitoring, electrophysiologic study (EPS) for ventricular tachycardia (VT), and treadmill exercise test. Sixty-nine consecutive patients with documented paroxysmal supraventricular tachycardia were included. Twenty-eight patients proved to have atrioventricular nodal reentrant tachycardia, and 41 patients had atrioventricular reciprocating tachycardia that involved accessory atrioventricular pathways. The first 34 patients received DC shock ablation and the other 35 patients received RF ablation. Signal-averaged ECG, Holter monitoring, and EPS for VT were performed before ablation, immediately after ablation, then 1 week, 2 weeks (Holter monitoring), 1 month (except EPS), and 3 months after ablation. Treadmill exercise testing was performed before ablation, and at 1 week and 3 months after ablation. The root mean square, low-amplitude signal and QRS duration of signal-averaged ECG disclosed no significant change after either DC or RF ablation up to 3 months. Late potential developed in only one patient in the DC shock group and it was considered to be innocuous because neither VT nor ventricular fibrillation was noted or induced. Increases in the number of ventricular premature contractions and in short-run VT were detected by Holter monitoring in the first week after either mode of ablation (p < 0.001 for the DC shock group; p < 0.05 for the RF group), which were greater (p < 0.05) and lasted longer in the DC shock group than in the RF group.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1993

Effect of mitral regurgitation and aortic regurgitation on Doppler-derived mitral orifice area in patients with mitral stenosis.

Traditional Doppler pressure half-time (T1/2) method (mitral valve area = 220/T1/2) is widely used for evaluating the mitral orifice area in patients with mitral stenosis (MS). However, the effect of mitral regurgitation (MR) and aortic regurgitation (AR) on the calculation of the mitral valve area by this method is still controversial. Therefore, we examined 493 consecutive patients with MS to evaluate the effect of MR and AR on Doppler-derived mitral orifice area. The mitral orifice area planimetered from two-dimensional echocardiogram was used as the standard reference. Excluding 16 patients with either unsatisfactory Doppler or echocardiographic tracings, 477 patients were enrolled in the study. There were 162 males and 315 females with a mean age of 49 years. They were divided into 4 groups: group A, 327 patients with MS but no MR and AR; group B, 68 patients with MS + MR but no AR; group C, 64 patients with MS + AR but no MR; group D, 18 patients with MS + MR + AR. The differences between echo and Doppler area were 0.02 +/- 0.02 cm2 (mean +/- SE), p = 0.220, in group A; 0.13 +/- 0.04 cm2, p = 0.004, in group B; 0.11 +/- 0.05 cm2, p = 0.026 in group C; and 0.31 +/- 0.08 cm2, p = 0.001, in group D. Thus, in patients with MS, the associated MR or AR may invalidate the pressure half-time method for the derivation of mitral valve area.

Adult↗
PubMed1992

A comparison between intravenous streptokinase and tissue plasminogen activator with early intravenous heparin in acute myocardial infarction.

To compare the effects of two thrombolytic agents, streptokinase and recombinant tissue-type plasminogen activator (rTPA) with early heparinization, on left ventricular function, coronary patency and reinfarction rates, bleeding complications, and short- and long-term mortality, we studied 122 patients with acute myocardial infarction prospectively. All of them fulfilled the standard criteria for thrombolytic therapy. One group (n = 63) received 1,500,000 units of streptokinase over 1 hour, and one group (n = 59) received 100 mg of rTPA over 3 hours. Baseline data showed no significant differences between the streptokinase and rTPA groups. Results of predischarge studies 10 to 14 days after infarction revealed that there was no difference in left ventricular ejection fraction between the two groups (48.3% in the streptokinase group and 49.9% in the rTPA group; p = 0.67). The patency rate of the infarct-related artery tended to be higher in the rTPA group compared with the streptokinase group (77% vs 57%, p = 0.19). In-hospital spontaneous bleeding occurred after streptokinase in seven patients (11.1%) and after rTPA in eight (13.6%; p = 0.89). One patient had intracranial bleeding after rTPA and died 13 hours later. The early mortality rate within 30 days of acute myocardial infarction was 5 of 63 (7.9%) for the streptokinase group and 2 of 59 (3.4%) for the rTPA group (p = 0.49). During the 19.3-month follow-up period, reinfarction occurred in seven patients (11%) in the streptokinase group and in three (5%) in the rTPA group (p = 0.3). The mortality rates were 10 of 63 (16%) and 3 of 59 (5%), respectively (p = 0.1).(ABSTRACT TRUNCATED AT 250 WORDS)

Aspirin↗
PubMed1992

Imaging of multiple coronary artery fistulas to right ventricle by transthoracic and transesophageal echocardiography.

A 20-year-old woman presented with extremely rare multiple coronary artery fistulas with left circumflex and right coronary arteries as the feeding vessels and two distinct sites of drainage into the posterior wall of the right ventricle near the apex in close proximity. The large left fistula was well depicted by transthoracic echocardiography, whereas the transesophageal approach better delineated part of the smaller right fistula.

Adult↗
PubMed1992

Peripartum cardiomyopathy.

Peripartum cardiomyopathy is a relatively rare complication of pregnancy, characterized by heart failure of obscure etiology during the antepartal or postpartal period. During a 10-year period in our hospital, of 36,882 women who delivered, 6 were diagnosed as having peripartum cardiomyopathy. The incidence in our hospital was estimated as 1:6,147 deliveries. Among these 6 patients, 2 cases with fulminating courses died 1 month after treatment. Two other cases had cardiomyopathy and multiple congestive heart failure and died after 3 years and 6 years. Only one case, whose cardiac size returned to normal within 4 months, completely recovered from this disease. Another survivor with persistent cardiomegaly was followed for 5 years and remained clinically stable. In addition to congestive heart failure, the occurrence of complications such as sepsis, hepatorenal failure, and arrhythmia were the major causes of death. According to the results of our study, return of cardiac chamber size to the normal range indicated a good prognosis. We concluded that the prognosis of peripartum cardiomyopathy depends upon the degree of cardiac dysfunction and the response to therapy.

Adult↗
PubMed1992

Effect of heart rate on pressure half-time in patients with mitral stenosis.

The effect of heart rate on pressure-half time has been controversial. This study attempted to clarify this issue in patients with mitral stenosis. Twenty cases were enrolled, 10 with atrial fibrillation and 10 with sinus rhythm. Twenty beats were analyzed for each patient. The results showed that in patients with atrial fibrillation the pressure half-time was hardly measurable in the cardiac cycles with a ventricular rate more than 100/min; by excluding these fast beats, the pressure half-time showed no relationship with the heart rate. Similarly, there was no significant correlation between heart rate and pressure half-time in patients with sinus rhythm when the heart rate was less than 70/min. However, if the sinus rate was more than 70/min, the correlation became statistically significant. We conclude that when using pressure half-time to derive mitral valve area we should avoid to use the beats with ventricular rate greater than 100/min in patients with atrial fibrillation. In patients with sinus rhythm, we should try to use those beats with heart rate greater than 70/min if possible. Otherwise, significant error may occur.

Adult↗
PubMed1992

Simplified continuity equation: a simple, accurate, and noninvasive method in the evaluation of aortic stenosis.

Traditional evaluation of aortic stenosis usually requires cardiac catheterization for estimation of aortic valve area by the Gorlin formula. However, it is invasive and has been shown to be inaccurate in the presence of aortic regurgitation or low cardiac output. Evaluation of aortic stenosis by Doppler echocardiography using a continuity equation has been proved to have excellent correlation with cardiac catheterization. It requires hand tracing and computer software for calculation of time velocity integral. Recently, a simplified continuity equation was introduced, which uses the peak velocities instead of time velocity integrals. It saves time and obviates the computer assistance. The purpose of this study is to evaluate its accuracy using the standard continuity equation as the reference standard. Seventy patients with pure or combined aortic stenosis were examined. There was an excellent correlation between these two methods (r = 0.979, 95% confidence interval: 0.978-0.980). The aortic valve area derived from the peak velocity method = 0.018 + 0.949 X aortic valve area derived from the time velocity integral. The difference between the two methods was 0.04 +/- 0.08 cm2 (mean +/- SD) with a 95% confidence interval of -0.12 to 0.20 cm2. Furthermore, the correlation still remained good even in the presence of significant aortic regurgitation or impaired left ventricular function. In conclusion, the simplified continuity equation is a safe, time-saving, and accurate method for the evaluation of aortic stenosis.

Adult↗
PubMed1991

Diagnosis of recurrent rupture of interventricular septum during acute myocardial infarction by Doppler color flow mapping.

This report presents a 60-year-old female who had acute anteroseptal myocardial infarction and a grade 3/6 pansystolic murmur at left lower sternal border. Color Doppler echocardiographic examination revealed the presence of a ventricular septal defect which was later confirmed by contrast left ventriculography and at the time of operation. Urgent operation with closure of ventricular septum was performed and the cardiac murmur disappeared. One day after operation a grade 3/6 pansystolic murmur at left lower sternal border was heard and hypotension was noted. Color Doppler echocardiographic examination demonstrated another ventricular septal defect. The patient underwent re-operation due to hemodynamic instability. At operation, a new ventricular septal defect was noted while the previous patch was intact.

Echocardiography, Doppler↗
PubMed1991

[Mitral annulus calcification: clinical observation on 72 patients].

This report presents 72 cases with mitral annulus calcification. The diagnosis was made by echocardiogram. There were 21 males and 51 females, aged from 38 to 93 (mean 71). The associated clinical findings in these 72 patients included: hypertension, 28 cases; valvular aortic stenosis, 3 cases; hypertrophic cardiomyopathy, 7 cases; chronic renal failure, 14 cases; congestive heart failure, 29 cases, calcified aortic valve, 27 cases; mitral regurgitation, 46 cases; cerebral infarct, 19 cases; peripheral arterial embolism, 2 cases. Their electrocardiographic findings included: atrial fibrillation, 25 cases; conduction defects, 21 cases; sick sinus syndrome, 3 cases (one case required permanent pacemaker implantation). We conclude that mitral annulus calcification is not a senile change only, and that it also results in some complications such as: mitral regurgitation, cerebral embolism, peripheral arterial embolism, atrial fibrillation and conduction defects. Echocardiography is a useful diagnostic tool in the evaluation of patients with mitral annulus calcification.

Adult↗