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Biomedical subjects

F C Lin

Publications and source records attributed to F C Lin.

At least 109 records · Page 6Linked to original sources
PubMed1988

Early diagnosis of acute myocardial infarction by myoglobin latex agglutination test.

Early elevation of the serum myoglobin level in acute myocardial infarction (AMI) has been noted for years. In this study, 39 patients admitted to the Coronary Care Unit with acute chest pain within 72 hours (mean 12 +/- 15 hours) or electrocardiographic changes suspected of acute myocardial infarction had a serum myoglobin latex agglutination test to evaluate its diagnostic accuracy in acute myocardial infarction. Of these 39 patients, 24 had documented acute myocardial infarction as their final diagnosis. By the time of admission, 18 of the 24 cases with infarction had positive myoglobin tests (sensitivity 75%). Of those 15 cases without myocardial infarction, 13 had negative myoglobin tests (specificity 87%). If only those 17 cases admitted within 5 hours of the onset of chest pain were analyzed, the serum myoglobin test became positive in 8 of 10 cases with documented AMI but the 2 cases with negative results turned positive 2 hours later (sensitivity 80% to 100%). Due to the fact that myoglobin tests were negative in all other 7 cases without infarction, the specificity was 7/7 (100%). In contrast, the creatine phosphokinase isoenzyme study was positive only in 3 of these 10 patients with documented AMI in the first blood sample taken during admission. In conclusion, the serum myoglobin latex agglutination test is a quick and reliable method that helps in the early diagnosis of acute myocardial infarction.

Adult↗
PubMed1987

Pharmacokinetics and pharmacodynamic effects of aqueous diltiazem in healthy humans.

Aqueous diltiazem was given to ten healthy male volunteers in a single oral dose of 2.5 mg/kg body weight. Serum diltiazem levels were measured at various intervals up to 24 hours after administration of the drug as were blood pressure, heart rate, and PR interval. The pharmacokinetics followed a one-compartment model in six and two-compartment model in four subjects. The mean distribution half-life in the latter four subjects was 15.8 +/- 3.7 minutes (range, 10.4-18.8 min). In the ten subjects, the peak serum diltiazem level was attained in 20 to 45 minutes (mean, 32.5 +/- 9.5 min) and ranged from 136 to 701 ng/mL (mean, 332 +/- 180 ng/mL). The elimination half-life ranged from 2.8 to 4.8 hours (mean, 3.8 +/- 0.6 hr). The area under the concentration-time curve varied from 508 to 2,245 ng-hr/mL, indicating differing bioavailability. Slight but significant blood pressure reduction was seen only at one to three hours. Changes in heart rate were not significant at any measurement. Transient facial flushing, beginning at ten to 20 minutes after administration, was noted in nine subjects, reflecting the vasodilatory effect of the drug. Significant prolongation (greater than 10%) of PR intervals began at ten minutes in three, at 20 minutes in six, and at 30 minutes in one participant, and progressed to second-degree Wenckebach atrioventricular (AV) block in six subjects 20 to 60 minutes after administration and third-degree AV block in one person 45 minutes after dosing. These AV blocks resolved by the third hour without treatment, and PR prolongation resolved by the fifth to seventh hours.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1987

Complete sinoatrial block in two patients with bradycardia-tachycardia syndrome.

Electrophysiologic studies with recordings of sinus node electrograms were performed in two patients with bradycardia-tachycardia syndrome. In both patients, the rest electrocardiogram showed apparent sinus bradycardia. Patient 1 had frequent paroxysms of atrial tachycardia with long pauses of up to 10 seconds; Patient 2 had paroxysmal atrial flutter and atrial pauses of up to 8 seconds. Multiple, repetitive, low frequency deflections, with a cycle length ranging from 730 to 960 ms in Case 1 and 570 to 750 ms in Case 2, suggestive of sinus node electrograms, were recorded at a critical area at the junction between the superior vena cava and the right atrium. These low frequency deflections had no relation to spontaneous junctional beats or the spontaneous atrial beats that showed high frequency deflections on the atrial electrogram. However, they could be suppressed by spontaneous or paced atrial beats. Pharmacologic interventions in Case 2 showed that the cycle length of the low frequency deflections shortened after administration of isoproterenol and did not change after propranolol or atropine. Thus, complete sinoatrial exit block with intact entrance conduction can occur in patients with bradycardia-tachycardia syndrome. Under such circumstances, the surface electrocardiographic manifestation of sinus bradycardia may not be of sinus origin.

Adult↗
PubMed1987

Outbreak of neonatal Citrobacter diversus meningitis in a suburban hospital.

Between February and June, 1983, four cases of Citrobacter diversus neonatal meningitis were identified at a suburban Baltimore hospital. One of the 4 infants died at age 13 months, 2 (both of whom had brain abscesses) have evidence of developmental delay and 1 appears to be normal after 33 months of follow-up. A review of microbiology records revealed that C. diversus had been present in the hospital nursery prior to identification of the first infant with meningitis, with isolation from infants born 7 months, 4 months and 4 days, respectively, before the first meningitis case. C. diversus was isolated from 21 infants born during the outbreak period and from hand or rectal cultures of 5 nursing personnel. All isolates were biotype E, with two distinct clusters of cases identified on the basis of plasmid profile and serotype. In a case-control study isolation of C. diversus was significantly associated with male sex, low birth weight and care by house pediatricians. The outbreak was controlled by stringent infection control measures and exclusion of personnel carriers. During the 24 months following the outbreak 3431 babies discharged from the nursery were cultured for C. diversus; 3 were colonized with the organism.

Citrobacter↗
PubMed1987

Diagnostic accuracy of two-dimensional echocardiography for detection of left atrial thrombus in patients with mitral stenosis.

Two-dimensional echocardiograms of 56 patients with mitral stenosis, who subsequently underwent operation, were analyzed to evaluate the accuracy for the detection of left atrial thrombi. From left parasternal, apical, and subcostal cardiac windows, multiple planes (including standard planes and their derived scanning planes) were assessed for the presence or absence of mass echoes in the left atrium. The results showed 63% sensitivity, 95% specificity, 87% positive predictive value, 84% negative predictive value, and 83% overall diagnostic accuracy. Most of the false-negative cases had their thrombi confined to the left atrial appendage. We conclude that in patients with mitral stenosis, two-dimensional echocardiography is promising for the diagnosis of left atrial thrombi, particularly when they locate or extend to the main left atrial cavity (not confined to atrial appendage).

Adult↗
PubMed1986

Paroxysmal supraventricular tachycardia initiated by a swallowing-induced premature atrial beat.

We report a unique patient in whom electrophysiologic studies elucidated the mechanism of a rare form of swallowing-induced atrioventricular reentrant tachycardia, and for whom successful surgical ablation of an accessory pathway abolished intractable episodes of palpitation. A 64-year-old man was incapacitated by frequent attacks of palpitation following swallowing. Electrocardiograms documented paroxysmal supraventricular tachycardias initiated by a premature atrial beat or beats following swallowing. During electrophysiologic studies swallowing consistently induced premature atrial beats which in turn initiated a sustained atrioventricular reentrant tachycardia incorporating a retrogradely conducting left-sided concealed accessory pathway. The atrial activation sequence related to the premature atrial beats and the morphology of the premature P waves suggested that premature atrial beats originated in the right atrium. The mechanism of induction of premature atrial beats following swallowing remains obscure in our patient. Antiarrythmic drugs failed to prevent induction of sustained tachycardias during sequential electrophysiologic studies. The patient underwent successful surgical ablation of the accessory pathway and is free from palpitation 15 months after the surgery.

Atrial Fibrillation↗
PubMed1986

Importance of adequate gas-mixing in contrast echocardiography.

Microbubble formation has been accepted as the mechanism producing contrast echoes. Comparisons of the contrast effects of various agents have been studied extensively, but the importance of gas-mixing has been less appreciated. To test the hypothesis that good gas-mixing, by facilitating microbubble formation, would enhance contrast effect, this study compared the contrast echocardiograms of ten adult patients before and after mixing carbon dioxide with various contrast agents. Contrast agents tested included a 5 percent glucose in water, vitamin B complex, vitamin C, and Cardiogreen solutions. First, we recorded echocardiograms by injecting each diluted contrast solution alone, then repeated the examinations using 10 ml of each diluted solution with 1 ml of carbon dioxide (CO2), mixed by means of a four-way stopcock. Satisfactory or excellent results were obtained in seven of ten, ten of ten, ten of ten, and ten of ten tests, respectively, after thorough gas-mixing, vs one of ten, seven of ten, eight of ten, and six of ten, respectively, before gas-mixing. We conclude that the addition of sufficient amounts of gas, followed by thorough mixing, is of great importance in contrast echocardiography. Consistently good results can be achieved with vitamin C, vitamin B or Cardiogreen solutions by this simple and safe method.

Adolescent↗
PubMed1985

Determinants of simultaneous fast and slow pathway conduction in patients with dual atrioventricular nodal pathways.

Double His bundle and ventricular responses to a single atrial impulse caused by a simultaneous fast and slow pathway conduction was observed during electrophysiologic study in three patients with dual-pathway atrioventricular nodal reentrant paroxysmal supraventricular tachycardia. In patient No. 1 this phenomenon occurred during rapid atrial pacing, in patient No. 2 during both rapid atrial pacing and delivery of a single atrial extrastimulus, and in patient No. 3 during delivery of double atrial extrastimuli. Retrograde unidirectional block in the slow pathway was suggested by retrograde induction of tachycardia at a long ventricular paced cycle length and/or long ventricular coupling interval in all three patients. Our findings suggest that major determinants of this phenomenon include: a sufficient conduction delay in the slow pathway so that the distal tissue is able to respond for the second time, and a retrograde unidirectional block in the slow pathway so that the fast pathway impulse will not enter and collide with the oncoming slow pathway impulse.

Atrioventricular Node↗
PubMed1985

Double atrial responses to a single ventricular impulse due to simultaneous conduction via two retrograde pathways.

Electrophysiologic studies were performed in two patients. In one patient (Case 1) with ventricular pre-excitation and paroxysmal supraventricular tachycardia, studies after diltiazem administration showed two QRS responses to a single atrial stimulus during atrial pacing at a cycle length of 300 ms. The first QRS response with full pre-excitation and short PR interval was consistent with accessory pathway conduction, while the second QRS response with a normal duration and an atrio-His bundle interval of 350 ms was consistent with normal pathway conduction. The second QRS response was followed by initiation of supraventricular tachycardia. Studies after verapamil administration on a separate day disclosed two atrial responses to a single QRS complex during ventricular pacing at cycle lengths between 330 and 280 ms, suggesting simultaneous retrograde accessory and normal pathway conduction. In Case 2 with a supraventricular tachycardia using a fast atrioventricular nodal pathway for anterograde and a slow ventriculoatrial pathway for retrograde conduction, two atrial responses to a single QRS complex were observed during ventricular pacing at cycle lengths between 500 and 400 ms. The first atrial response showed a stimulus to atrial interval of 120 ms and an atrial activation sequence with the low septal right atrium being earlier than other atrial sites, suggesting retrograde fast pathway conduction. The second atrial response showed a stimulus to atrial interval of 505 ms and an atrial activation sequence with low septal right atrium being simultaneous with the proximal coronary sinus, suggesting retrograde slow pathway conduction.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1985

Pseudosimultaneous fast and slow pathway conduction: a common electrophysiologic finding in patients with dual atrioventricular nodal pathways.

Two ventricular responses following termination of rapid atrial pacing were noted in 24 of 87 patients with dual atrioventricular (AV) nodal pathways and supraventricular tachycardia. In all 24 patients, the AH intervals of the first and second ventricular responses were comparable with those of the fast and slow pathways, respectively. Careful analysis of the whole pacing sequence revealed that, in 21 patients, this phenomenon resulted from sustained slow pathway conduction with long AH intervals. In these patients, as the AH interval of each paced beat was progressively lengthened during pacing, the corresponding His bundle and ventricular responses were pushed one cycle behind the current atrial paced beat, so that the last paced beat was followed by two His bundle and ventricular responses. In only three patients did double ventricular responses result from simultaneous fast and slow pathway conduction. One of these three patients also showed two ventricular responses resulting from sustained slow pathway conduction. Several factors predispose to the occurrence of this phenomenon in patients with dual AV nodal pathways. These include an ability to sustain slow pathway conduction, a longer slow pathway AH interval, a shorter sinus AH interval (fast pathway) and a shorter atrial paced cycle length that sustains slow pathway conduction. In conclusion, sustained slow pathway conduction with resultant long AH intervals is the mechanism of two ventricular responses following termination of atrial pacing in most patients with dual AV nodal pathways. This phenomenon should be distinguished from the rare occurrence of double ventricular responses to an atrial impulse due to simultaneous fast and slow pathway conduction.

Adolescent↗
PubMed1985

Assessment of blood collection systems for the high performance liquid chromatography measurement of propranolol.

The effect of blood collection devices on the high performance liquid chromatography (HPLC) measurement of propranolol was assessed. Blood was collected from hypertensive patients treated with propranolol for at least 7 days. Two venipunctures (opposite arm technique) were performed on each patient using the reference (syringe/silanized, ethylene diamintetraacetate tubes) procedure and the Vacutainer Brand Tubes (lavender-, royal blue-, green-, and red-stoppered) that were free of tris(2-butoxyethyl) phosphate. Propranolol concentrations were determined utilizing a published HPLC procedure. This study showed that in the four evacuated tubes, propranolol concentrations in serum or plasma were highly correlated to those of the reference procedure (correlation coefficients, 0.986 to 0.997; and slope, 0.912 to 1.013). Mean propranolol concentrations of the red-stoppered tube serum were lower (7.5%) than that of the reference syringe (0.01 less than p less than 0.05). Thus, lavender-, royal blue-, green-, and red-stoppered tubes would be acceptable for propranolol monitoring.

Blood Specimen Collection↗
PubMed1985

Termination of paroxysmal supraventricular tachycardia with a single oral dose of diltiazem and propranolol.

The efficacy of a single oral dose combination of 120 mg diltiazem and 160 mg propranolol in terminating paroxysmal supraventricular tachycardia (PSVT) was evaluated in 15 patients. All 15 patients underwent electrical induction of PSVT that lasted longer than 15 min, and all underwent randomized crossover placebo and diltiazem and propranolol studies on 2 consecutive days. On each day PSVT was induced and placebo or diltiazem and propranolol was administered 15 min later. Electrical conversion of PSVT was performed when severe symptoms occurred or at the end of 240 min. With placebo PSVT lasted 164 +/- 89 (mean +/- SD) min; four patients had spontaneous conversion. With diltiazem and propranolol PSVT lasted 39 +/- 49 min (p less than .001); 14 patients had spontaneous conversion in an average of 27 +/- 15 min. None of the 14 patients had electrical reinduction of sustained PSVT after conversion. The sinus nodal recovery time during spontaneous or electrical conversion of PSVT was 911 +/- 459 msec with placebo and 1076 +/- 270 msec with diltiazem and propranolol (NS). Two patients developed transient second-degree atrioventricular block and junctional rhythm while on diltiazem and propranolol. Serum diltiazem and propranolol levels (ng/ml) after diltiazem and propranolol in five patients were, respectively, 49 +/- 26 and 108 +/- 101 at 15 min, 232 +/- 147 and 228 +/- 148 at 30 min, 254 +/- 169 and 370 +/- 393 at 45 min, 280 +/- 115 and 209 +/- 189 at 60 min, 188 +/- 72 and 268 +/- 264 at 120 min, and 118 +/- 57 and 265 +/- 148 at 240 min.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1985

Serial electrophysiologic studies of the effects of oral diltiazem on paroxysmal supraventricular tachycardia.

In 16 patients with paroxysmal supraventricular tachycardia, electrophysiologic studies were done before and serially at hourly intervals for eight hours after the third oral dose of 90 mg diltiazem given every eight hours. Diltiazem increased both the longest atrial paced cycle length producing type 1 atrioventricular block and the effective refractory period of the atrioventricular conducting system at all measurements. Before diltiazem, all 16 patients had induction of sustained tachycardia. After diltiazem, sustained tachycardia could not be induced in ten patients at any measurements; in these patients, either echo or nonsustained tachycardia was induced. In the remaining six patients, sustained tachycardia was induced, particularly after six hours. Follow-up observations in 12 patients receiving the same dosage of oral diltiazem for 6 +/- 2 months (mean +/- SD), showed that of the eight patients in whom electrophysiologic testing induced either echo or nonsustained tachycardia, six were asymptomatic and two experienced transient palpitation. Of the other four patients with induction of sustained tachycardia, three had transient palpitation and one had occasional attacks of sustained tachycardia requiring modification of therapy. Thus, oral diltiazem increases atrioventricular nodal refractoriness, with an effect lasting up to eight hours. It is an effective agent for the prophylaxis of paroxysmal supraventricular tachycardia.

Administration, Oral↗
PubMed1985

Early postoperative echocardiographic studies of atrial septal defects.

Fifteen consecutive adult patients with uncomplicated atrial septal defects (ASD) underwent echocardiographic examinations both before and 3-8 days (mean 7 days) after surgery to study the early postoperative changes in cardiac dimensions and interventricular septal motion. Echocardiographic analyses included patterns of interventricular septal motion, right and left ventricular dimensions at end-diastole (RVDd & LVDd), aortic root dimension at end-diastole (ARDd) and left atrial dimension at end-systole (LADs). The results showed that the septal motion was abnormal in 87% (13/15) before and 40% (6/15) after operation. RVDd decreased from 36 +/- 7 mm to 27 +/- 7 mm (p less than 0.01) while LVDd increased from 33 +/- 6 mm to 39 +/- 4 mm (p less than 0.01). There were no significant changes in LADs and ARDd after surgery. These observations suggest that in patients with ASD the ventricular dimensions and patterns of interventricular septal motion are changed significantly shortly after surgical repair.

Adolescent↗