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Biomedical subjects

Y T Tai

Publications and source records attributed to Y T Tai.

At least 109 records · Page 6Linked to original sources
PubMed1990

Improvement in exercise performance and hemodynamics by labetalol in patients with idiopathic dilated cardiomyopathy.

Labetalol, a combined alpha- and beta-blocking agent, was administered to 12 patients (mean age 55 years) with idiopathic dilated cardiomyopathy to examine its effects on symptomatology and exercise performance. Studies were performed before treatment, after 8 weeks of placebo, and after 8 weeks of labetalol therapy in a randomized, crossover, double-blind design. The mean (+/- SEM) dose of labetalol for the group was 275 +/- 29 mg. Compared to treatment with placebo, the maximum duration of symptom-limited exercise was significantly prolonged with labetalol (580 +/- 72 seconds to 683 +/- 71 seconds; p less than 0.005). Both the resting and peak exercise heart rate and systolic blood pressure were significantly reduced. Ascending aortic blood flow velocity was also measured by continuous-wave Doppler technique during exercise. Compared to placebo, treatment with labetalol conferred no significant change in cardiac output at rest but significantly improved cardiac output at maximum exercise (14 +/- 3%; p less than 0.001). Doppler-derived peak aortic flow velocity, acceleration, and flow velocity integral were also significantly improved at maximum exercise. Systemic vascular resistance, as derived from mean blood pressure/cardiac output, was reduced by 12 +/- 3% and 16 +/- 3% at rest and at maximum exercise, respectively. New York Heart Association functional class was improved (3.2 +/- 0.2 to 2.2 +/- 0.3; p less than 0.005). No major side effects from labetalol were encountered. Thus labetalol improves symptomatology, exercise capacity, and exercise hemodynamics and reduces systemic vascular resistance in patients with idiopathic dilated cardiomyopathy.

Cardiomyopathy, Dilated↗
PubMed1990

Left posterior fascicular tachycardia due to localized microreentry.

Fascicular tachycardia in young patients without overt heart disease constitutes a rare but electrophysiologically distinct arrhythmia entity. Microreentry within the left posterior fascicle has been proposed as its mechanism, but evidence for this is inconclusive. This report details a patient with incessant fascicular tachycardia. The electrophysiological features, in particular the pattern of resetting response, provided strong evidence for reentry as the tachycardia mechanism. Satisfactory long-term arrhythmia control was achieved with flecainide.

Adult↗
PubMed1990

'Leopard' syndrome.

'Leopard' syndrome is a rare inherited disorder associated with a high prevalence of cardiac abnormalities. General anaesthesia for dental treatment in a patient who had cardiomyopathy and bizarre electrocardiographic abnormalities associated with this syndrome is described. A thorough cardiac assessment is advised in a patient with multiple lentigines, although no clinical symptoms or signs may be found. Even if no cardiac abnormality is found before it is better to re-assess the patient, since abnormalities may develop later. The assessment should be repeated if any abnormality was detected before but without clinical significance, since the disease is progressive and may progress more rapidly in some patients than in others.

Adolescent↗
PubMed1990

Reentrant fascicular tachycardia with cycle length alternans: insights into the tachycardia mechanism and origin.

This report details the electrophysiology of a unique case of reentrant fascicular tachycardia in a patient without structural heart disease. Persistent cycle length alternans, with constant fluctuation in alternate RR intervals, occurred during tachycardia. A distinct mode of spontaneous termination of tachycardia was observed. The findings were consistent with the presence of decremental conduction properties in the tachycardia circuit or decremental dual functional pathways within one limb of the circuit. These observations provide further evidence in support of a fascicular origin of the tachycardia.

Bundle of His↗
PubMed1990

Pacemaker mediated tachycardias in single chamber rate responsive pacing.

Although pacemaker mediated tachycardias are classically associated with dual chamber pacemakers, single chamber rate responsive pacemakers are also susceptible to such tachycardias under special circumstances. A unipolar activity sensing rate responsive pacemaker (Activitrax 8403) was implanted in an 83-year-old man with complete atrioventricular block. The pacemaker was programmed at an output of 5 V, activity threshold medium, rate response 5, and lower and upper rates of 70 and 125 beats/min, respectively. He presented with palpitations at rest and muscle twitching of the pacemaker pocket 4 months after implantation. Examination confirmed that the pacemaker had flipped over, resulting in pocket pacing which in turn activated the activity sensor, resulting in a rate response. The increase in pacing rate lead to a higher frequency of pocket pacing, thus leading to positive feedback increase in rate. With the patient at rest, pacemaker mediated rates were 106, 91, and 74 beats/min at low, medium and high thresholds, respectively. Decreasing the output to 2.5 V eliminated pocket pacing and the tachycardia. As a result of the reversal of the pacemaker, a similar rate response during exercise could only be achieved at a more sensitive rate responsive setting. Thus, pacemaker mediated tachycardia can complicate pacemaker "flipping" in single chamber activity sensing rate responsive pacemakers. Methods for the avoidance and treatment of pacemaker flipping are discussed. A review of other sensor mediated tachycardias is also presented.

Aged↗
PubMed1990

Adverse effect of topical methylsalicylate ointment on warfarin anticoagulation: an unrecognized potential hazard.

The adverse effect of topical methylsalicylate ointment on warfarin anticoagulation is studied in 11 patients. All patients had an abnormally elevated international normalized ratio after significant usage of topical methylsalicylate ointment as obvious from both the clinical history and a positive blood level of salicylate. Out of the 11 patients, 3 had bleeding manifestation; 2 with bruises and 1 with gastrointestinal bleeding. It is concluded that topical methylsalicylate ointment should be prescribed with care to patients on warfarin and excessive usage is to be avoided since potentially dangerous drug interaction could occur.

Administration, Topical↗
PubMed1990

Anticoagulation instability with life-threatening complication after dietary modification.

Anticoagulation instability due to a change in intake of vitamin K after dietary modification was observed in 2 patients on long-term oral anticoagulants. One patient developed diffuse bruises treated conservatively with fresh frozen plasma transfusion and the other had a thrombosed aortic prosthesis which required emergency operation. To prevent such complications, dietary modification especially with food rich in vitamin K should be undertaken with care in patients on long-term oral anticoagulants.

Adult↗
PubMed1990

Doppler-echo evaluation of left ventricular diastolic filling in patient with mixed connective tissue disease.

Left ventricular diastolic function was assessed in 17 patients (2 males and 15 females; mean age 44 +/- 9 years) with mixed connective tissue disease (MCTD) and 18 sex- and age-matched healthy control subjects (2 males and 16 females; mean age 44 +/- 8 years) by means of M-mode and pulsed Doppler echocardiography. None had clinical evidence of overt myocardial disease or abnormal left ventricular systolic function. Compared with the control group, patients with MCTD had a significantly longer isovolumic relaxation time (IVRT) (59 +/- 7 versus 70 +/- 12 ms; p less than 0.01), a lower peak early diastolic flow velocity (E) (0.79 +/- 0.10 versus 0.70 +/- 0.07 m/s; p less than 0.005), a higher peak late diastolic flow velocity due to atrial contraction (A) (0.47 +/- 0.08 versus 0.54 +/- 0.08 m/s; p less than 0.05) and a reduced E/A ratio (1.72 +/- 0.37 versus 1.33 +/- 0.26; p less than 0.005). Although there was no significant correlation of left ventricular diastolic filling indexes with age, heart rate, left ventricular end-diastolic and end-systolic dimensions, interventricular septal and left ventricular posterior wall thickness, and fractional shortening, the duration of illness was significantly related to IVRT (r = 0.62; p less than 0.01), peak A (r = 0.79; p less than 0.001) and velocity half-time (r = 0.54; p less than 0.05). The results suggest the presence of an abnormal left ventricular diastolic filling pattern in patients with MCTD and may represent myocardial involvement in this disease.

Adult↗
PubMed1990

Successful resuscitation and survival following massive overdose of metoprolol.

A 23-year-old female was found unconscious and deteriorated rapidly to cardiac asystole. Prolonged resuscitation was required, and she remained in severe cardiogenic shock, despite high doses of positive inotropic agents. Massive beta-adrenoceptor blocker overdose was suspected (and subsequently confirmed). IV administration of glucagon was followed by prompt haemodynamic improvement and recovery, illustrating the beneficial role of glucagon in overwhelming beta-adrenoceptor blockade.

Adult↗
PubMed1990

Echocardiographic identification of mitral valvular abnormalities in patients with mixed connective tissue disease.

To evaluate cardiac involvement in mixed connective tissue disease (MCTD), M-mode, 2-dimensional and pulsed Doppler echocardiography were performed in 17 patients with MCTD. Pericardial abnormalities were present in 4 patients (24%), including small pericardial effusion (less than 1 cm) in 2 patients and pericardial thickening in 2 patients. Verrucous thickening of the mitral valve was detected in 2 patients (12%) by 2-dimensional echocardiography. Pulsed Doppler echocardiography revealed the presence of mild mitral regurgitation in one of them. To our knowledge, such mitral valve abnormalities have not been reported. Future larger studies are needed in order to evaluate the incidence and natural evolution of these mitral valvular abnormalities.

Adult↗
PubMed1989

False detection of left atrial thrombus by the angiographic sign of "neovascularity".

"Neovascularity" in the region of the left atrial appendage was demonstrated by coronary arteriography preoperatively in five patients with mitral valve disease and was attributed to the presence of thrombus in the left atrium. Subsequently, they underwent surgery, but thorough inspection of the left atrium did not reveal thrombus in any of the five patients. The presence of neovascularity without apparent thrombosis or false detection may be a result of tissue reaction and organization in an effort to resorb the thrombus.

Adult↗
PubMed1989

Left ventricular pseudoaneurysm after replacement of the mitral valve: long-term survival and spontaneous closure.

Left ventricular pseudoaneurysms, with or without overt ventricular rupture, are usually fatal in the absence of prompt surgical intervention. This report details the long-term survival of a patient who developed a left ventricular pseudoaneurysm following repair of ventricular rupture subsequent to replacement of the mitral valve, with spontaneous closure of the "neck" of the pseudoaneurysm.

Aged↗
PubMed1989

Latent functional duality in an accessory pathway.

Accessory atrioventricular pathways classically possess neither decremental conduction nor functional duality. This report details an accessory pathway in which functional longitudinal dissociation, with decremental ventriculoatrial conduction in each component, was observed after, but not before, administration of the antiarrhythmic drug recainam.

Adult↗
PubMed1989

Cardiac tamponade complicating leukaemia: immediate chemotherapy or pericardiocentesis?

Although leukaemic infiltration of the pericardium is frequently observed at post-mortem, clinically evident cardiac tamponade is rare. Two cases of cardiac tamponade complicating leukaemia are presented. One patient had cardiac tamponade as the initial presentation of acute lymphoblastic leukaemia and experienced complete resolution of the pericardial effusion within 6 days after chemotherapy without therapeutic pericardiocentesis. The other patient with chronic myeloid leukaemia developed cardiac tamponade requiring pericardiocentesis as the first sign of acute blastic transformation. The roles of early chemotherapy and pericardiocentesis in managing this complication are discussed.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1988

Hemodynamic consequences of supraventricular tachycardias and their antiarrhythmic treatment.

Complex adjustments in contractility, resistance, stroke volume and atrio-ventricular contraction relationships underlie the optimization of cardiac output during variations in sinus rate. In patients with intra AV nodal re-entry tachycardia and accessory pathway tachycardias, rate and loss of appropriately timed atrial transport reduce cardiac efficiency, but this is serious only when heart rates are very high. True atrial tachycardia, atrial fibrillation, and atrial flutter are often associated with cardiovascular disease. In atrial fibrillation and flutter, loss of atrial transport may be less important than the hemodynamic consequences of irregularity of ventricular systole. Antiarrhythmic management may ameliorate the consequences of the arrhythmia by reducing heart rate, restoring sinus rhythm or more controversially by regularizing ventricular contraction. Digoxin and antiarrhythmic surgery have little negative inotropic potential but most other antiarrhythmic drugs and ablation procedures depress myocardial function. Antitachycardia pacemakers may produce acute adverse hemodynamic effects depending upon the type of pulse trains delivered to terminate the tachycardia.

Anti-Arrhythmia Agents↗
PubMed1986

Disseminated zygomycosis masquerading as cerebral lupus erythematosus.

Zygomycosis often occurs in patients with an underlying disease, e.g., diabetes mellitus, leukemia, and lymphoma, or an immunocompromised state. This report discusses a case of a 21-year-old woman with systemic lupus erythematosus complicated by uremia, acidosis, steroid therapy, prolonged antimicrobial therapy, and disseminated zygomycosis.

Adult↗