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Biomedical subjects

P Kuan

Publications and source records attributed to P Kuan.

At least 19 recordsLinked to original sources
PubMed1992

Morphologic characterization and quantitative assessment of mitral regurgitation with ruptured chordae tendineae by transesophageal echocardiography.

To compare the accuracy of transesophageal echocardiography (TEE) with that of transthoracic echocardiography (TTE) in the detection of morphologic characteristics and in the quantitative assessment of the severity of mitral regurgitation with ruptured chordae tendineae, 40 patients with ruptured chordae tendineae (group 1) and 20 patients with moderate or severe mitral regurgitation due to other causes (group 2) were studied. All echocardiograms were recorded before cardiac surgery. Cardiac catheterization was performed in 55 patients (92%). TEE showed greater sensitivity and negative predictive value than TTE (100 vs 65%, and 100 vs 56%, respectively; p < 0.005) in the diagnosis of ruptured chordae tendineae. Visualization of the ruptured chordae (termed snake-tongue sign) was highly sensitive and specific (93 and 95%, respectively) for establishing the diagnosis of ruptured chordae tendineae. The severity of mitral regurgitation in group 1 patients evaluated by TTE color flow mapping was underestimated by 2 grades in 1 patient and by 1 grade in 6 patients, and overestimated by 1 grade in 1 patient, compared with left ventriculography. In contrast, by TEE color flow mapping it was underestimated by 1 grade in 1 and overestimated by 1 grade in 1 patient. TEE color flow mapping showed better correlation with angiography than did TTE color flow mapping (r = 0.82 vs r = 0.49).

Adult↗
PubMed1992

Reappraisal by transesophageal echocardiography of the significance of left atrial thrombi in the prediction of systemic arterial embolization in rheumatic mitral valve disease.

Systemic arterial embolization imparts a significant risk of serious complications throughout the lives of patients with rheumatic heart disease. Left atrial (LA) thrombi have been thought to be the major source of emboli. A transesophageal echocardiography (TEE) study of 260 consecutive patients with rheumatic mitral valve disease was performed during a period of 24 months, with particular reference to understanding the association between LA thrombi and embolic complications. Of these patients, 155 had predominant mitral stenosis, 24 had significant mitral regurgitation, and the remaining 81 with xenograft mitral valve replacement developed valvular dysfunction (25 resulted in predominant mitral stenosis and 56 in significant mitral regurgitation). LA thrombi were detected in 38 patients (group A) and absent in 222 (group B). Group A patients had a higher frequency of recent (less than or equal to 1 week before TEE study) and remote (greater than 1 week before) embolization than did group B patients (recent: 26.3 vs 5.4% [p less than 0.001]; remote: 18.4 vs 5.0% [p less than 0.01]). The frequency of atrial fibrillation was also greater in group A patients (100 vs 74.3%; p less than 0.001). The exclusion of patients with significant mitral regurgitation and sinus rhythm had no effect on the association between LA thrombi and evidence of previous embolization. It is concluded that TEE is a convenient diagnostic modality that can be used to identify a subset of patients with rheumatic mitral valve disease at high risk for systemic embolization. Consequently, preventive anticoagulation for possible embolic complications should be more vigorously adhered to in patients with rheumatic mitral valve disease and LA thrombi.

Echocardiography↗
PubMed1992

Prospective study of blood culture during transesophageal echocardiography.

To ascertain the incidence and significance of bacteremia associated with transesophageal echocardiography (TEE), 132 consecutive patients (aged 17 to 73 years) free of apparent infection who were undergoing 135 transesophageal echocardiographic procedures from October 1990 to August 1991, were prospectively studied. For each procedure, two sets of blood cultures were obtained for culture 30 to 60 minutes before TEE, immediately after, and 180 to 240 minutes after the procedure. For each blood culture, 10 ml of venous blood was evenly inoculated into aerobic and anaerobic culture bottles and inoculated for 7 days using a radiometric system. A throat swab was obtained immediately before each procedure. Three of 270 preprocedure blood cultures were positive for Bacillus cereus, Staphylococcus simulans, and Peptostreptococcus species, respectively. No blood culture was positive in the immediate postprocedure period. Two of 270 late blood samples grew Staphylococcus epidermidis in the same patient. Nevertheless, the microorganisms isolated from blood cultures were different from those isolated from the throat swab. No patients had fever or evidence of infective endocarditis after TEE during the follow-up period. It is concluded that the incidence of TEE-related bacteremia is extremely low, and a general recommendation for antibiotic prophylaxis during TEE is not warranted.

Adolescent↗
PubMed1992

Detection of patent foramen ovale by contrast transesophageal echocardiography.

A series of 32 patients undergoing cardiac catheterization and/or operation to document the presence of patent foramen ovale (PFO) were studied. All were examined by contrast transthoracic echocardiography (TTE) and transesophageal echocardiography (TEE) during normal breathing and the Valsalva maneuver. A right-to-left shunt at the atrial level was visualized by contrast TEE in 14 patients during normal breathing and in 20 patients during the Valsalva maneuver. In comparison, contrast TTE revealed this shunt in only eight patients during normal breathing and in 12 patients during the Valsalva maneuver. All of the foramina proved to be patent by contrast TTE were also found by contrast TEE. All but one (19 of 20) patients, shown to have PFO by contrast TEE, could be confirmed at cardiac catheterization and/or operation. Using cardiac catheterization and/or operation as a gold standard, contrast TEE appears to be a more sensitive (100 percent vs 63 percent, p less than 0.005) and accurate (97 percent vs 78 percent, p less than 0.05) method than contrast TTE in the detection of PFO.

Adolescent↗
PubMed1992

Clinical efficacy of transluminal extraction coronary atherectomy.

Mechanical revascularization has revolutionized the treatment of coronary artery disease. The transluminal extraction-endarterectomy catheter (TEC) system was developed recently and permits the excision and extraction of atherosclerotic lesions of the coronary artery and the bypass graft. The system includes a motor-driven flexible torque catheter with rotating conical shaped stainless steel blades distally. The proximal end of the TEC system consists of a mechanical housing which controls the vacuum, the rotating cutter (750 RPM) and the cutter excursion (4 cm). After safety testing of the TEC system in dogs and human peripheral arterial disease, percutaneous transluminal coronary atherectomies employing the TEC have been performed in 25 patients (six women, 19 men, mean age, 64 +/- 12 years) with the diameter of the stenosis greater than or equal to 75% in one or more coronary arteries. Twenty-eight atherosclerotic lesions were treated in 26 native coronary arteries. The overall success rate (less than 50% residual stenosis in all lesions) was 92%. There was one instance of hematoma proximal to the excised target lesion, and one instance of atherectomized debris embolization. There were no instances of dissection, perforation, coronary spasms or death related to the procedure. The results indicate that the TEC system can be used safely and effectively to treat coronary artery disease with a high success rate.

Adult↗
PubMed1992

Metastasis of hepatocellular carcinoma to the heart: unusual patterns in three cases with antemortem diagnosis.

Unusual patterns of cardiac metastasis were noted in three cases of hepatocellular carcinoma (HCC): one patient was noted to have a large right ventricular (RV) tumor mass with intracavitary growth and myocardial invasion; the second had massive pulmonary and left atrial (LA) metastasis; and the third patient had a right atrial tumor mass with concomitant RV and LA involvement. Tumor implantation to the RV without right atrial involvement and extensive myocardial invasion is unusual in HCC. The LA involvement is probably related to tumor growth from the pulmonary veins following massive metastasis to the lung, direct invasion of the atrial septum or tumor implantation via a subclinical right-to-left shunt through the patent foramen ovale. To the best of our knowledge, such unusual intracavitary metastases in HCC have not been reported previously. Cardiac metastasis, without local gross recurrence, may be one of the presentations after lobectomy in patients with HCC.

Adult↗
PubMed1992

Inheritance of hypertrophic cardiomyopathy in Chinese--M-mode and two-dimensional echocardiographic analysis of 28 families.

To determine the mode of inheritance and degree of penetrance of hypertrophic cardiomyopathy (HC) in Chinese, 132 family members of 28 probands with HC were assessed by M-mode and two-dimensional echocardiography. Of these 132, 103 cases were first-degree relatives of the probands. Twenty-seven (20.4%) family members, including 19 cases of first-degree relatives of the probands, had HC. Familial occurrence of HC was noted in 13 (46.4%) families. In 10 families, the affected relatives were identified in successive generations, and the mode of inheritance was most consistent with an autosomal dominant trait. The frequency with which HC was identified in relatives increased significantly with the number of subjects studied and a positive family history of sudden death. Subgroup analysis, using multivariate logistic regression analysis, revealed that increasing age was independently associated with a higher frequency of definite cases in first-degree relatives of the probands. In contrast, by multivariate analysis, there were no significant differences between frequency of definite cases in female and male relatives or in different familial relationships (parent, sibling, offspring) to the probands.

Adolescent↗
PubMed1992

Coronary atherectomy with the transluminal extraction endarterectomy catheter.

Percutaneous transluminal coronary atherectomy was attempted in 25 consecutive patients with the transluminal extraction-endarterectomy catheter. Successful revascularization with residual stenosis less than 50% in diameter was achieved in 23 patients (92%). There were 2 cases of major complications: one with distal embolization which subsided after rtPA infusion and the other with occlusion of RCA underwent bypass surgery. One patient who had restenosis 3 months after the procedure, was successfully treated with PTCA. The technical aspects, advantages and limitations of this method were discussed.

Adult↗
PubMed1991

Atypical myxoma.

We report the case of a 38-year-old woman with a large thin-walled cystic mass (6 x 5 x 4.5 cm) filled with arterial blood in the right atrium. The cystic mass with blood content was clearly delineated by transesophageal cross-sectional echocardiography and magnetic resonance imaging of the heart. At operation, a silver-whitish, smooth surfaced cystic mass was found attached to the free wall of the right atrium between the superior vena cava and the right atrial appendage with a broad base. Microscopically, the wall of the cyst was composed of stellate mesenchymal cells embedded within a myxoid matrix which was proved by alcian blue stain. To our knowledge, this type of cardiac myxoma has not been previously reported.

Adult↗
PubMed1987

Differences between acute and long-term metabolic and endocrine effects of oral beta-adrenoceptor agonist therapy with pirbuterol for cardiac failure.

The metabolic, hormonal and haemodynamic effects of oral pirbuterol, a new beta 2-adrenoceptor agonist, were studied acutely (n = 19) and after 3 months treatment (n = 11) in patients with severe heart failure receiving chronic frusemide therapy. In the acute study fasted patients (n = 10) showed reductions in plasma K+ (P less than 0.005) and cortisol (P less than 0.01) and increases in plasma glucose (P less than 0.005), insulin (P less than 0.01), lactate (P less than 0.005) and pyruvate (P less than 0.0025). These acute changes were less in unfasted subjects (n = 9). Maximal increase in stroke volume occurred at approximately half the plasma pirbuterol concentration required for maximal effect on plasma insulin. Treatment with pirbuterol for 3 months was associated with sustained increases in stroke volume and fasting plasma glucose and insulin, but there was loss of all other acute metabolic effects. Despite concurrent frusemide and digoxin therapy acute hypokalaemia caused no adverse effects. Hypokalaemia did not occur with chronic pirbuterol administration.

Adult↗
PubMed1987

Cardiac Wilson's disease.

Wilson's disease is a multisystem disorder. Heart involvement in Wilson's disease, however, has rarely been recognized. A prospective study was undertaken of 53 consecutive patients (28 men and 25 women, mean age of 21.4 years) with Wilson's disease. Electrocardiographic abnormalities occurred in 18 of 53 patients (34 percent), including left ventricular hypertrophy, biventricular hypertrophy, early repolarization, ST depression and T inversion, premature atrial or ventricular contractions, atrial fibrillation, sino-atrial block, Mobitz type 1 atrioventricular block, and tremor artifact. In contrast, 26 medical students and 14 carriers of Wilson's disease as control subjects (mean age of 22.6 years) all showed normal ECG. Eight out of 43 patients (19 percent) demonstrated asymptomatic orthostatic hypotension. An abnormal response to the Valsalva maneuver occurred in six of 18 patients (33 percent). There were two cardiac deaths; one died of repeated ventricular fibrillation (the copper content in the myocardium was 2.28 micrograms/g, and in the bundle of His 1.21 micrograms/g wet weight in the autopsy specimen); and the other, of dilated cardiomyopathy. It is concluded that four modes of cardiac manifestations in Wilson's disease include arrhythmias, cardiomyopathy, cardiac death, and autonomic dysfunction. Such possible cardiac involvement should be added to the clinical picture of Wilson's disease involving the hepatic and central nervous system.

Adolescent↗
PubMed1983

Symptoms, haemodynamics, and exercise capacity during long term treatment of chronic heart failure. Experience with pirbuterol.

An open study of long term treatment with an oral beta 2 agonist (pirbuterol 20 mg three times daily) was undertaken in 63 patients with severe chronic heart failure. During three months of treatment 20 (32%) patients died, of whom 16 were taking the drug at the time of death. Mortality was related to initial functional class (New York Heart Association classification: 23% in grade III and 75% in grade IV). Concomitant treatment with digoxin did not affect mortality. The drug was well tolerated by most patients but unwanted side effects necessitated withdrawal of the drug in six (10%). Thirty-five patients were continuing to take the drug after three months, of whom 22 reported symptomatic improvement and only four deterioration. There was a relation between symptomatic improvement and increase in exercise capacity. At initial haemodynamic assessment a single dose of pirbuterol increased the cardiac index by 34% and the stroke index by 21%. Left ventricular filling pressure fell by 23% and systemic vascular resistance by 22%. Haemodynamic reassessment after three months of continuous treatment in 29 patients showed maintained improvement in the group as a whole, although individual variation was considerable. There was no apparent relation between haemodynamic improvement and improvement in exercise duration and symptoms. Severe heart failure has a poor prognosis. Identification of those patients who may derive benefit from treatment with a particular drug is not yet possible.

Adrenergic beta-Agonists↗
PubMed1981

Treatment of chronic heart failure with pirbuterol: acute haemodynamic responses.

Fifty-nine patients with severe chronic heart failure were given pirbuterol, a beta agonist with vasodilator and positive inotropic properties. The acute haemodynamic responses to both single (20 patients) and incremental doses (39 patients) were measured. Pirbuterol increased cardiac index and reduced left ventricular filling pressure and systemic vascular resistance with only small changes in heart rate and blood pressure. Maximal effects were observed at an average of 170 minutes after a single oral dose of pirbuterol. In the incremental dose studies the plasma pirbuterol concentration was found to increase with increasing doses and was related to the magnitude of the haemodynamic response. Pirbuterol was well tolerated, and no drug-related side effects were recorded. Oral pirbuterol clearly improved pump performance in these patients, the haemodynamic changes being consistent with vasodilatation as the dominant mechanism rather than a direct inotropic effect.

Administration, Oral↗