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Biomedical subjects

F C Lin

Publications and source records attributed to F C Lin.

At least 55 records · Page 3Linked to original sources
PubMed1996

Video-assisted cardiac surgery. Preliminary experience in reoperative mitral valve surgery.

OBJECTIVES: Video-assisted endoscopic techniques had been applied in the surgical correction of patent ductus arteriosus, vascular ring, or coronary artery disease. However, it has been used only recently in the correction of reoperative mitral valve lesions. DESIGN: Video-assisted cardiac operations were performed on four patients who had received surgical interventions on their mitral valves and needed emergent reoperation. PATIENTS: Four patients (3 men and 1 woman) received emergency surgery from September to December 1995 for thrombosis of mechanical mitral prosthesis (2 patients) and severe mitral regurgitation with previously failed mitral valve repair (2 patients). Six previous operations had been performed on these mitral valves. Patient ages ranged from 26.7 to 68.1 years (mean, 47.3 years). Preoperatively, acute pulmonary edema occurred in two patients, cerebral emboli occurred in one patient, and sepsis was found in one patient. Mechanical ventilatory support was used in two patients before operation. INTERVENTION: The operations were performed through right anterior minithoracotomy, guided by video-assisted endoscopic techniques with femoro-femoral extracorporeal circulation. The operative procedures were thrombectomy of mitral prosthesis in two patients, mitral valve repair in one patient, and mitral valve replacement in one patient. RESULTS: The duration of extracorporeal circulation was 166 to 320 min (222 +/- 67 min) and the operation time was 4.6 to 6.8 h (6.1 +/- 1.0 h). All patients recovered from the operations rapidly with uneventful postoperative courses except 1 patient who had sepsis preoperatively and died 2 months later. CONCLUSION: Our experience demonstrates that video-assisted cardiac surgery is technically feasible and could be performed in reoperation of the mitral valve.

Adult↗
PubMed1996

Hypoxemia in a cirrhotic patient caused by hepatopulmonary syndrome: a case report.

Hepatopulmonary syndrome (HPS) is the triad of liver disease, pulmonary vascular dilatation, and abnormal arterial oxygenation. We report a case with progressive orthodeoxia and platypnea who was proven to have HPS after serial investigations, including autopsy. This 61-year-old male is a case of alcoholic liver cirrhosis without any documented cardiopulmonary disorders before. However, he suffered from progressive dyspnea in his last one-year life. During that period, progressive severe hypoxemia, orthodeoxia and platypnea were detected. Serial non-invasive diagnostic approaches, including two-dimensional contrast enhanced echocardiography and technetium-99m labeled macroaggregated albumin (MAA) lung perfusion scanning, were performed and showed positive evidence of intrapulmonary shunting. Direct evidence of intrapulmonary vascular dilatation was finally proven by autopsy. Although this syndrome is not rare, clinical awareness of the association between liver disease and arterial oxygen desaturation is still inadequate. We report a case proved by typical clinical manifestation and complete investigation and review the literature to emphasize this important disorder.

Cyanosis↗
PubMed1996

Retrograde atrio-His bundle dissociation as a sign indicative of retrograde accessory pathway conduction.

Electrophysiologic study and radiofrequency ablation therapy were performed in a 36-year-old male with Wolff-Parkinson-White syndrome and Ebstein's anomaly. The study disclosed the presence of a posteroseptal accessory pathway and dual atrioventricular (AV) nodal pathways. Retrograde atrio-His bundle (A-H) dissociation was noted during rapid ventricular pacing, in which the atria were activated by retrograde impulse from the accessory pathway with a fixed ventriculo-atrial (VA) interval while the retrograde His bundle potential was visible during the diastolic isoelectric period due to the occurrence of Wenckebach periodicity within the His-Purkinje system. This phenomenon is a useful sign for rapid recognition of the accessory pathway conduction.

Adult↗
PubMed1995

The role of Saccharomyces cerevisiae type 2A phosphatase in the actin cytoskeleton and in entry into mitosis.

We have prepared a temperature-sensitive Saccharomyces cerevisiae type 2A phosphatase (PP2A) mutant, pph21-102. At the restrictive temperature, the pph21-102 cells arrested predominantly with small or aberrant buds, and their actin cytoskeleton and chitin deposition were abnormal. The involvement of PP2A in bud growth may be due to the role of PP2A in actin distribution during the cell cycle. Moreover, after a shift to the non-permissive temperature, the pph21-102 cells were blocked in G2 and had low activity of Clb2-Cdc28 kinase. Expression of Clb2 from the S.cerevisiae ADH promoter in pph21-102 cells was able to partially bypass the G2 arrest in the first cell cycle, but was not able to stimulate passage through a second mitosis. These cells had higher total amounts of Clb2-Cdc28 kinase activity, but the Clb2-normalized specific activity was lower in the pph21-102 cells compared with wild-type cells. Unlike wild-type strains, a PP2A-deficient strain was sensitive to the loss of MIH1, which is a homolog of the Schizosaccharomyces pombe mitotic inducer cdc25+. Furthermore, the cdc28F19 mutation cured the synthetic defects of a PP2A-deficient strain containing a deletion of MIH1. These results suggest that PP2A is required during G2 for the activation of Clb-Cdc28 kinase complexes for progression into mitosis.

Actins↗
PubMed1995

Multiplane transesophageal echocardiography in the diagnosis of congenital coronary artery fistula.

The purpose of this study was to examine the advantages of multiplane transesophageal echocardiography in the diagnosis of congenital coronary artery fistula, specifically in depicting the origin, the course, and the drainage site. Seven consecutive patients ranging in age from 20 to 72 years with a suspected coronary artery fistula underwent conventional transthoracic and multiplane transesophageal echocardiographic studies between March 1993 and July 1994. When a coronary artery fistula was noted, the origin, the course, and the drainage site were carefully searched for. All patients then underwent a cardiac catheterization with the performance of coronary angiography. A large right coronary artery fistula was detected in three patients; one of them had a drainage to the posterior left ventricle, one to the lateral right ventricle, and the other to the medial aspect of the right ventricle just below the insertion of the septal leaflet of the tricuspid valve. A small coronary artery fistula arising from the left coronary artery was noted in four patients, two from the left anterior descending artery and the other two from the left circumflex artery. Three of these four patients had a drainage to the main pulmonary artery and one to the left ventricle. The drainage site was clearly depicted in all seven patients, whereas the origin and the course were precisely defined in five patients by using multiplane transesophageal echocardiographic examination. The multiplane transesophageal echocardiography provides a panoramic view of the coronary artery and the fistulous vessel with a precise definition of the origin, the course, and the drainage site of the fistula. Therefore it is the noninvasive diagnostic mode of choice.

Adult↗
PubMed1995

Progression to complete atrioventricular block in a patient with bundle branch re-entry tachycardia.

A 38-year-old man with no significant structural heart disease suffered from one episode of wide QRS tachycardia. The electrocardiogram showed a PR interval of 0.20 second and a QRS duration of 0.10 second. His bundle recording revealed an HV interval of 90-100 ms. The tachycardia was inducible with programmed stimulation and displayed a QRS morphology of complete left bundle branch block. It was characterized by an atrioventricular dissociation, a cycle length of 280 ms, and an H deflection preceding each QRS complex. Pacing from the right ventricular apex at a cycle length of 270 ms entrained the tachycardia, while at a cycle length of 260 ms, the tachycardia was terminated. Four years later, the patient presented with complete atrioventricular block with a wide QRS escape rhythm. An electrophysiologic study conducted while he was in 1:1 atrioventricular conduction showed an HV interval of 100 ms. Second-degree infrahisian block developed at an atrial paced cycle length of 700 ms. There was no induction of tachycardia with programmed stimulation before or after isoproterenol. The patient was treated with an implantation of a permanent pacemaker.

Adult↗
PubMed1995

Diagnosis of coronary artery dissection following blunt chest trauma by transesophageal echocardiography.

How to differentiate relevant from trivial cardiac injury in blunt chest trauma has been an ongoing debate. In a 32-year-old victim of a motorcycle crash, the electrocardiographic pattern of an acute anterior wall myocardial infarction was identified as being due to a dissection, after an intimal flap in the proximal left anterior descending artery was noted on transesophageal echocardiography.

Adult↗
PubMed1995

Radiofrequency ablation therapy in concealed left free wall accessory pathway with decremental conduction.

An electrophysiologic study followed by transcatheter radiofrequency ablation therapy was performed in two adult patients with a permanent form of junctional tachycardia. Both patients had no structural heart disease and exhibited a normal resting ECG. The P wave during tachycardia was negative in leads 1, 3, and aVF, biphasic over V6, and positive in V1 and aVL in both patients, while the P-R/R-P interval ratio during tachycardia was 0.82 and 0.36, respectively, in both patients. Both patients displayed an eccentric atrial activation sequence with the earliest atrial activation occurring at the distal coronary sinus and a decremental retrograde conduction property during incremental ventricular pacing, suggesting the presence of a concealed slowly conducting left free wall accessory pathway. The tachycardia used the normal atrioventricular pathway for anterograde conduction and the concealed show left accessory pathway for retrograde conduction. It was terminated following adenosine administration in both patients; termination of tachycardia was due to a block in the retrograde accessory pathway in one patient and due to a block in the atrioventricular node in the other patient. Radiofrequency ablation was performed by the retrograde transaortic approach. The radiofrequency f4p4ent was delivered to the site of the earliest atrial activation during tachycardia at the ventricular aspect of the mitral annulus. The successful ablation site had a ventriculoatrial (VA) interval of 120 and 130 ms, respectively, and was located at the posterolateral and lateral aspects of the mitral annulus. Following ablation, there was no VA conduction; however, conduction through the normal atrioventricular pathway was noted during isoproterenol infusion in both patients. There was no induction of tachycardia. This study demonstrates that the permanent form of junctional tachycardia in adults can incorporate a concealed left free wall accessory pathway with a decremental property. Radiofrequency ablation therapy is effective and safe in this form of arrhythmia.

Adult↗
PubMed1994

Characteristics and radiofrequency ablation therapy of intermediate septal accessory pathway.

Fourteen patients (5%) with an intermediate septal accessory pathway were identified among 283 consecutive patients with the Wolff-Parkinson-White syndrome who had electrophysiologic study and radiofrequency ablation therapy. Nine were women and 5 were men (mean age 33 +/- 13 years). The resting electrocardiogram showed ventricular preexcitation in 8 patients and normal PR interval in 6. Anterograde and retrograde mapping studies revealed that the accessory pathway was para-Hisian in 11 patients and paranodal in 3. The accessory pathway was successfully ablated in 10 patients (9 para-Hisian and 1 paranodal) and damaged in 1 (para-Hisian). Treatment of 3 patients was complicated by transient atrioventricular (AV) block, of 1 by intermittent second-degree AV block, and of another by permanent complete AV block requiring implantation of a permanent pacemaker. Six patients underwent a follow-up electrophysiologic study 84 +/- 55 days after ablation; none had induction of tachycardia even after isoproterenol infusion. It is concluded that radiofrequency ablation therapy for intermediate septal accessory pathway is feasible. However, the success rate is only modest (71%), whereas complications with heart block (36%) or complete right bundle branch block (29%) are high. Thus, the procedure should be reserved for patients with life-threatening or troublesome symptomatic tachyarrhythmias.

Adolescent↗
PubMed1994

Estimation of pulmonary artery pressure from pulmonary vein wedge pressure.

Correlations between pulmonary artery and pulmonary vein wedge pressures were investigated in 13 patients with atrial septal defect and 1 patient with Tetralogy of Fallot. Pulmonary vein wedge pressure wave form resembled that of pulmonary artery pressure, and the former lagged behind the latter by 70 to 110 msec (mean 88 +/- 14) as observed by the fluid-filled catheter system. Diastolic pulmonary artery and diastolic pulmonary vein wedge pressures were nearly identical. Although systolic and mean pulmonary artery pressures correlated well with respective pulmonary vein wedge pressures, there were discrepancies when systolic and mean pulmonary artery pressure exceeded 35 and 20 mm Hg, respectively. However, systolic and mean pulmonary artery pressures could be estimated by adding the difference between the diastolic pulmonary vein wedge pressure and the mean left atrial pressure to corresponding systolic or mean pulmonary artery pressure. In conclusion, pulmonary artery pressures can be estimated by measuring pulmonary vein wedge pressures and the mean left atrial pressure.

Adult↗
PubMed1994

Radiofrequency ablation therapy in atypical or multiple atrioventricular node reentry tachycardias.

Electrophysiologic study and radiofrequency ablation therapy were performed in 23 patients with atypical (8 patients) or multiple (15) atrioventricular node reentry tachycardias. Dual pathways with anterograde fast and slow pathway conductions were demonstrated in 16 patients. Studies on retrograde conduction revealed the presence of three different pathways, including fast (15 patients), intermediate (17), and slow (16). The radiofrequency current was applied to the inferior aspect, one-third anterior two-thirds posterior between the His bundle and the ostium of the coronary sinus, of Koch's triangle along the tricuspid annulus in all patients. Application of the current resulted in selective ablation or modification of both retrograde intermediate and slow pathway conductions in 20 patients. In two patients retrograde fast pathway conduction was also modified. Complete atrioventricular block occurred in the remaining patient. Sixteen patients had no induction of tachycardia or echo, 4 had induction of a single echo, and 2 had induction of the slow-fast form tachycardia; one of those 2 patients underwent a second trial and was successful. A median application of 2 was delivered at a power of 25 +/- 5 W and a duration of 18 +/- 4 sec. The total fluoroscopic time was 25 +/- 21 minutes. The anterograde fast pathway conduction was unaffected; the shortest atrial paced cycle length that sustained 1:1 fast pathway conduction was 329 +/- 65 msec and 330 +/- 68 msec before and after ablation, respectively. A follow-up electrophysiologic study was performed in 16 patients 60 +/- 15 days after ablation. Eleven had no induction of tachycardia or echo, and five had induction of < 3 echoes. This study demonstrated that radiofrequency ablation with the inferior approach is effective and safe in atypical or multiple atrioventricular node reentry tachycardias. It resulted in ablation of the slow pathway and retrograde intermediate pathway conduction with preserved atrioventricular conduction.

Adult↗
PubMed1994

Late clinical and electrophysiologic outcome of radiofrequency ablation therapy by the inferior approach in atrioventricular node reentry tachycardia.

A late electrophysiologic study was conducted in 182 of 289 patients with slow-fast atrioventricular node reentry tachycardia 81 +/- 36 days after radiofrequency ablation therapy by the inferior approach. Of these 182 patients, electrophysiologic study immediately after ablation revealed a selective modification of the slow pathway in 159, a modification of both the slow and fast pathways in 15, a modification of the fast pathway alone in 3, and failure of ablation in 5. One hundred two patients had no induction of echoes; 75 had induction of fewer than four echoes; and 5 had induction of sustained tachycardia with or without isoproterenol infusion. The late electrophysiologic study in these 182 patients revealed a persistent effect without changes in conduction properties in 161 (88%) patients. A change in conduction properties was noted in 21 patients, including 5 with resumption of slow- or fast-pathway conduction with induction of sustained tachycardia, 8 with improved fast- or slow-pathway conduction, and 8 with an additional depression of fast- or slow-pathway conduction. Of the 102 patients with no induction of echoes and the 75 patients with induction of fewer than four echoes during the immediate postablation electrophysiologic study, 5 (3 and 2, respectively) patients had induction of tachycardia. Of the 5 patients with induction of sustained tachycardia in the immediate postablation electrophysiologic study, 3 continued to have induction of sustained tachycardia; 1 had induction of echoes only; and 1 had no induction of echoes.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1994

Double loop figure-of-8 reentry as the mechanism of multiple atrioventricular node reentry tachycardias.

Seven patients with multiple atrioventricular node reentry tachycardia were analyzed to unravel the mechanism of these tachycardias. Six of the seven patients showed anterograde dual atrioventricular node pathways and one showed anterograde conduction through the fast pathway. Three types of retrograde pathways were noted among these seven patients: (1) the fast pathway with the earliest atrial activation at the His bundle area; (2) the intermediate pathway with the earliest atrial activation at the ostium of the coronary sinus; and (3) the slow pathway with the earliest atrial activation at the ostium of the coronary sinus. All seven patients used the intermediate pathway for retrograde conduction. However, one patient showed evidence of retrograde slow pathway conduction with demonstrable retrograde dual pathways, and another showed evidence of retrograde fast pathway conduction with a shift of atrial activation sequence when conduction switched to the intermediate pathway. Four different types of reentry circuits using either the fast or the slow pathway as the anterograde limb and one of the three retrograde pathways as the retrograde limb were demonstrated in these seven patients, resulting in two types of tachycardias in four patients and three types of tachycardias in three patients. A change in tachycardia type could be induced with atrial or ventricular stimulation. A radiofrequency current delivered to the inferior aspect of Koch's triangle along the tricuspid anulus in five patients resulted in selective ablation or modification of the intermediate pathway or the slow pathway, with preservation of anterograde atrioventricular conduction and abolition of tachycardias. The findings suggest that a double loop figure-of-8 reentry circuit including a fast pathway, a slow pathway, and an intermediate pathway is responsible for multiple atrioventricular node reentry tachycardias.

Adult↗
PubMed1994

Radiofrequency ablation therapy in idiopathic left ventricular tachycardia with no obvious structural heart disease.

BACKGROUND: The feasibility and efficacy of radiofrequency ablation therapy in idiopathic left ventricular tachycardia has not been assessed in a large group of patients. METHODS AND RESULTS: Twenty consecutive patients with idiopathic left ventricular tachycardia and without structural heart disease underwent electrophysiological study, pharmacological interventions with administration of verapamil and adenosine, and radiofrequency ablation therapy. There were 17 men and 3 women with a mean age of 28 +/- 8 years. The QRS configuration during tachycardia was of right bundle branch block and superior axis in 13 patients, indeterminate axis in 6 patients, and right axis in 1 patient. The tachycardia was electrically inducible and responsive to verapamil but not to adenosine. Thirteen patients demonstrated entrainment. Activation and pace-mapping studies disclosed that the tachycardia originated from the inferior apical septum in 15 patients, the midseptum in 4 patients, and the anterior lateral wall of the left ventricle in 1 patient. Radiofrequency ablation was successful in 17 of the 20 patients (85%). The successful ablation sites were characterized by an endocardial activation time 30 milliseconds earlier than the onset of QRS during tachycardia and by a pace-mapping QRS similar to or closely resembling the tachycardia. All patients displayed sharp spikes preceding the local ventricular electrogram at the ablation site. However, these sharp spikes also were noted in 15 control patients and were not specific for this tachycardia; they persisted after ablation. There were no complications. A follow-up of 7 +/- 8 months in the 17 successfully ablated patients showed no symptomatic tachyarrhythmias without medications. Six patients underwent repeat electrophysiological study, and no induction of tachycardia was revealed. CONCLUSIONS: Radiofrequency ablation therapy is effective and safe in patients with idiopathic left ventricular tachycardia. It should be considered as the primary therapeutic modality in these patients.

Adult↗
PubMed1994

Concertina-like phenomenon in ventricular preexcitation due to spontaneous atrioventricular nodal Wenckebach periodicity.

Electrophysiologic study and radiofrequency ablation therapy were performed in a 28-year-old male patient with the Wolff-Parkinson-White syndrome and electrocardiographic manifestation of concertina phenomenon. His bundle recordings showed a sinus cycle length of 720 = ms with a cyclic variation of QRS morphologies of every 3 beats and an antidromic atrial echo following the last fully preexcited QRS complex. After successful radiofrequency ablation of a left posterior accessory pathway, spontaneous 3:2 atrioventricular nodal Wenckebach periodicity was noted and the mechanism of the concertina phenomenon was unraveled.

Adult↗