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Yanfei Yang

Publications and source records attributed to Yanfei Yang.

At least 19 recordsLinked to original sources
PubMed2026

The Inflammation-Thrombosis Genetic Axis in Abdominal Aortic Aneurysm: A Shared Roadmap to Precision Medicine.

Abdominal Aortic Aneurysm (AAA) is characterized by persistent inflammation, extracellular matrix loss, and intraluminal thrombus formation, yet the genetic links among these processes remain incompletely defined. Here, we examine evidence that genetic variation can influence inflammatory and thrombotic responses at the same time. Findings from genome-wide association studies are considered alongside transcriptomic, proteomic, single-cell, epigenetic, and experimental data. Particular attention is given to candidate genes and signaling networks relevant to AAA susceptibility, enlargement, and rupture. The available evidence supports a model in which inherited susceptibility alters the balance between vascular inflammation, coagulation, fibrinolysis, and wall repair. However, many reported loci still lack functional confirmation, and most genetic data come from populations of European ancestry. Defining the causal variants and the cells in which they act will be necessary before these findings can be used for individualized screening or treatment.

abdominal aortic aneurysm↗
PubMed2005

Structural toxicity relationship of 4-alkoxyphenols' cytotoxicity towards murine B16-F0 melanoma cell line.

PURPOSE: The aim of this study was to identify phenolic agents that could form quinone reactive intermediate metabolites in melanocytes in order to be effective as anti-melanoma agents; but were not metabolized by liver P450 metabolizing enzymes in order to have minimal toxicity towards the liver. METHODS: Tyrosinase, an enzyme present abundantly in melanocytes was selected as a molecular target for the treatment of malignant melanoma. Ten alkoxyphenols were investigated for their metabolism by tyrosinase/O2, rat liver P450 microsomal/NADPH/O2 metabolizing systems and for their toxicity towards B16-F0 melanoma cells. RESULTS: All the alkoxyphenols showed a dose- and time-dependent toxicity towards B16-F0 cells except 2-iso-propoxyphenol. 4-n-hexyloxyphenol demonstrated the greatest toxicity towards B16-F0 cells while minimally depleting glutathione in microsomal preparations at its calculated LC10 and LC50 lethal concentrations for B16-F0. At 100 microM concentrations, 4-t-butoxyphenol showed the lowest amount of glutathione depletion by microsomal P450 system. Alkoxyphenols with at least two alkyl groups derivatized at alpha carbon of alkoxy group showed minimal rates of metabolism by tyrosinase/O2 metabolizing system. A quantitative structural toxicity relationship equation was also derived, LogLC50(mM)= -0.265(+/-0.064)LogP + 2.482(+/-0.179). CONCLUSIONS: 4-n-hexyloxy-phenol was identified as a potential lead anti-melanoma agent against B16-F0 melanoma cells with minimal metabolism by rat liver P450 microsomal preparation.

Alcohols↗
PubMed2005

Protected circumferential conduction in the posterior atrioventricular vestibule of the left atrium: electrophysiologic and anatomic correlates.

BACKGROUND: The anatomic substrate for protected isthmus conduction in the right atrium has been well defined. Little is known of similar substrates in the left atrium (LA). METHODS: Patients (pts) with reentrant tachycardia (AVRT) supported by a single left-sided accessory pathway were studied retrospectively (n = 64) and prospectively (n = 31). Intracardiac electrograms were recorded from the His bundle position and coronary sinus (CS). The LA was mapped with a steerable catheter using the transseptal approach. LA anatomy was examined grossly and histologically in six cadaver hearts after removal of endocardium. RESULTS: A distal-to-proximal CS activation sequence during AVRT was seen in all patients with a left lateral accessory pathway before ablation. After one to three radiofrequency (RF) energy deliveries that did not interrupt accessory pathway conduction, the CS activation sequence was reversed in three patients in the retrospective group and bidirectional conduction block in the posterior atrioventricular vestibule of the LA (PAVV) was demonstrated in nine patients in the prospective group. Four of the six cadaver hearts showed a distinct circumferential inferoposterior myocardial bundle that coursed parallel to the CS in the PAVV. CONCLUSIONS: We described evidence of bidirectional intraatrial block in the PAVV after application of RF energy during accessory pathway ablation. Such conduction block may mimic the presence of a second accessory pathway. Our data suggest that circumferential conduction in the PAVV may be poorly coupled to the rest of the LA and may be involved in the macro-reentrant circuit around the mitral annulus. The circumferential inferoposterior myocardial bundle may serve as the underlying anatomic substrate.

Adult↗
PubMed2005

Reentry within the cavotricuspid isthmus: an isthmus dependent circuit.

BACKGROUND: We describe a new cavotricuspid isthmus (CTI) circuit. METHODS: This study includes 8 patients referred for atrial flutter (AFL) ablation whose tachycardia circuit was confined to the septal CTI and the os of the coronary sinus (CS(OS)) region. Entrainment mapping was performed within the CTI, CS(OS), and other right atrial annular sites (tricuspid annulus (TA)). Electroanatomic mapping was available in 2 patients. RESULTS: Sustained AFL occurred in all patients with mean tachycardia cycle length (TCL) of 318 +/- 54 (276 - 420) ms. During tachycardia, fractionated or double potentials were recorded at either the septal CTI and/or the region of CS(OS) in all, and concealed entrainment with post-pacing interval (PPI)--TCL < or = 25 ms occurred in this area; but manifest entrainment with PPI > TCL was demonstrated from the anteroinferior CTI and other annular sites in 7/8 patients. In one, tachycardia continued with conduction block at the anteroinferior CTI during ablation. Up to three different right atrial activation patterns (identical TCL) were observed. The tachycardia showed a counterclockwise (CCW) pattern in 6, a clockwise pattern in 2, and simultaneous activation of both low lateral right atrium and septum in 5. Electroanatomic mapping was available in 2, showing an early area arising from the septal CTI in 1, and a CCW activation sequence along the TA in another. Radiofrequency application to the septal CTI terminated tachycardia in 4, and tachycardia no longer inducible in all. CONCLUSIONS: We describe a tachycardia circuit confined to the septal CTI/CS(OS) region, and hypothesize that this circuit involves slow conduction within the CTI and around the CS(OS), which acts as a central obstacle.

Aged↗
PubMed2005

Site specificity of transverse crista terminalis conduction in patients with atrial flutter.

INTRODUCTION: The causes of transcristal conduction (TC) in patients with atrial flutter (AFL) are unknown. METHODS AND RESULTS: In two groups of patients referred for AFL ablation, 36 had cavotricuspid isthmus (CTI) dependent flutter (Group I) and 24 had lower (n = 21) or upper loop reentry (n = 5) (Group II). After ablation, isthmus block was evaluated by pacing from the coronary sinus (CS) and low lateral right atrium and by alternative techniques, including mapping with electrodes spanning the CTI or electroanatomic mapping. After bidirectional CTI block was verified, 21/36 (58%) in Group I showed TC with CS pacing, including low TC in 16 (including 11 showing "pseudo" CTI conduction), higher TC in 6 and multiple breaks in 3. However, 8 with low TC during CS pacing showed unidirectional block by pacing outside of the CS os. Twelve (50%) in Group II had TC during CS pacing after bidirectional CTI block, with low TC in 5 (2 mimicking residual CTI conduction) and higher breaks in 9. There was no significant difference in the incidence of TC during CS pacing after CTI block between groups. In seven autopsied hearts, the muscle orientation between the proximal CS musculature and Eustachian ridge were examined. Muscular connections between the CS and Eustachian ridge coursing toward the orifice of inferior vena cava were found in one of the hearts. CONCLUSIONS: It is concluded that in patients with bidirectional CTI block, pacing from the CS may be associated with TC mimicking a conduction leak through the isthmus. Pacing just outside the CS os helps distinguish pseudo from true isthmus block.

Aged↗
PubMed2005

The history of AV nodal reentry.

Though patients with AV nodal reentry are now routinely cured by catheter ablation, the basic mechanism of this disorder is still under debate. The putative mechanism of AV node reentry was first discovered by the elegant work of Gordon Moe. He demonstrated the existence of dual pathways and echo beats in rabbits. Building on these seminal observations, the mechanism of AVNRT has burgeoned to include the possibility of left atrial input into the node. The first curative nonpharmacologic procedures involved surgical dissection around the AV node and the procedure was rapidly supplanted by catheter ablation procedures. The initial ablative procedure targeted the fast pathway, but later observations showed that ablation of the slow pathway was more effective and safer. Cure of AV nodal reentry which is the most common cause of paroxysmal supraventricular tachycardia became possible through the cooperative efforts of anatomists, physiologists, surgeons, and clinical electrophysiologists.

Cardiology↗
PubMed2004

Use of ibutilide in cardioversion of patients with atrial fibrillation or atrial flutter treated with class IC agents.

OBJECTIVES: We sought to assess the efficacy and safety of ibutilide cardioversion for those with atrial fibrillation (AF) or atrial flutter (AFL) receiving long-term treatmentwith class IC agents. BACKGROUND: Attenuation of ibutilide-induced QT prolongation has been observed in a small number of patients pretreated with class IC agents. The clinical significance of the interaction between ibutilide and class IC agents is unknown. METHODS: Seventy-one patients with AF (n = 48) or AFL (n = 23), receiving propafenone 300 to 900 mg/day (n = 46) or flecainide 100 to 300 mg/day (n = 25), presented for ibutilide (2.0 mg) cardioversion. RESULTS: The mean durations of arrhythmia episode and arrhythmia history were 25 +/- 48 days and 4.4 +/- 6.4 years, respectively. Sixty-five patients (91.5%) had normal left ventricular systolic function. Twenty-three of 48 patients (47.9%; 95% confidence interval, 33.3% to 62.8%) with AF and 17 of 23 patients (73.9%; 95% confidence interval, 51.6% to 89.8%) with AFL converted with mean conversion times of 25 +/- 14 min and 20 +/- 12 min, respectively. There was a small increase in corrected QT interval after ibutilide (from442 +/- 61 ms to 462 +/- 59 ms, p = 0.006). One patient developed non-sustained polymorphous ventricular tachycardia and responded to intravenous magnesium. Another developed sustained torsade de pointes and was treated effectively with direct-current shock and intravenous dopamine. CONCLUSIONS: Our observations suggest that the use of ibutilide in patients receiving class IC agents is as successful in restoring sinus rhythm and has a similar incidence of adverse effects as the use of ibutilide alone.

Aged↗
PubMed2004

Left septal atrial flutter: electrophysiology, anatomy, and results of ablation.

BACKGROUND: We describe the clinical and electrophysiological characteristics of a novel macroreentrant form of left atrial flutter circuit. METHODS AND RESULTS: A total of 11 patients were included in the study. The mean tachycardia cycle length was 278+/-41 ms. Nine of the 11 patients were treated with antiarrhythmic drugs at the time of the study for concomitant atrial fibrillation. With the use of entrainment pacing and either the CARTO Biosense mapping system (9 patients) or conventional mapping (2 patients), the flutter circuit was found to rotate around the left septum primum with a critical isthmus located between the pulmonary veins posteriorly and/or mitral annulus anteriorly and the septum primum. In 5 patients, radiofrequency ablation was performed from the septum primum to the right inferior pulmonary vein (group 1), and in 6 patients, a lesion was made from the septum primum to the mitral annulus (group 2). After a follow-up of 13+/-6 months, 2 patients in group 1 and all patients in group 2 remained in sinus rhythm without recurrence. CONCLUSIONS: Slowing of electric conduction in the left atrial septum due to antiarrhythmic drugs and/or atrial myopathy seems to promote left septal atrial flutter. Radiofrequency ablation of this arrhythmia is usually effective and safe. A line of block between the septum primum and the mitral annulus proved to be effective for cure of tachycardia.

Aged↗
PubMed2004

Lower loop reentry as a mechanism of clockwise right atrial flutter.

BACKGROUND: Right atrial reentrant tachycardia resulting from lower loop reentry (LLR) around the inferior vena cava (IVC) has been described recently. However, all reported cases of LLR in the literature have negative flutter waves on the inferior surface ECG leads similar to that of counterclockwise typical atrial flutter around the tricuspid annulus (TA). Right atrial flutter with positive flutter waves in the inferior ECG leads has been assumed to rotate as a single reentrant activation wave front around the TA, and the role of LLR in those patients is not known. METHODS AND RESULTS: Twelve consecutive patients with flutter wave morphology on surface ECG consistent with clockwise atrial flutter were studied. The endocardial activation pattern recorded from conventional multipolar electrode catheters was characteristic of clockwise atrial flutter around the TA. Entrainment pacing in all 12 patients and 3D activation sequence mapping in 7 patients, however, revealed clockwise LLR involving the lower right atrium around the IVC in 7 patients, figure-of-8 double-loop reentry around both the IVC and TA in 4, and single reentrant loop around the TA in 1. Linear radiofrequency ablation in the isthmus between the TA and IVC (TI isthmus) terminated the tachycardia in all patients. CONCLUSIONS: Surface ECG flutter wave morphology and limited recording intracardiac sites proved insufficient to delineate the precise mechanism of the TI isthmus-dependent clockwise right atrial flutters. Most right atrial flutters with positive flutter wave on surface ECG may be supported by a reentrant circuit around the IVC or a figure-of-8 double-loop reentry involving both the IVC and TA.

Aged↗
PubMed2003

Surface electrocardiographic characteristics of right and left atrial flutter.

BACKGROUND: There is little information about the surface expression of non-cavotricuspid isthmus (CTI)-dependent right atrial (RA) or left atrial (LA) flutter circuits. METHODS AND RESULTS: We retrospectively evaluated 32 episodes (in 26 patients) of atypical RA and 22 episodes (in 21 patients) of LA flutter. The surface ECG of 13 patients with lower-loop reentry was similar to that of their pattern during counterclockwise (CCW) CTI atrial flutter (AFL), except for decreased amplitude of the terminal forces in the inferior leads. In 11 of 24 episodes characterized by high or multiple breaks over the crista, the ECG showed changes that depended on the initial activation sequence of the LA. In 7 of 8 episodes of upper-loop reentry, the ECG pattern completely mimicked that for clockwise (CW) CTI AFL. All 11 patients with an LA septal circuit showed a typical ECG pattern characterized by prominent forces in lead V1 with flat deflections in the other surface leads. Eleven patients with other LA circuits had a more variable pattern but showed decreased voltage in the inferior leads compared with that of a group with CCW-CTI AFL (1.6+/-1 vs 2.68+/-0.7 mV, respectively; P<0.05). CONCLUSIONS: The RA surface-ECG patterns different from those of CCW or CW-CTI could still be CTI dependent. In contrast, a typical CW-CTI surface pattern was always seen in patients with upper-loop reentry, which was non-CTI dependent. LA AFL circuits had either flat or low-amplitude forces in the inferior leads.

Aged↗
PubMed2003

Significance of bundle branch block during atrioventricular nodal reentrant tachycardia.

There are very limited data on the effects of bundle branch block (BBB) in patients with atrioventricular nodal reentrant tachycardia (AVNRT). Studies in a total of 155 patients with 162 episodes of AVNRT were retrospectively analyzed. A total of 38 patients (25%) developed spontaneous right BBB, whereas 5 (3%) developed left BBB during tachycardia. Five of the 38 (13%) with right BBB showed near identical prolongation of both the ventriculoatrial (VA) (15 +/- 5 ms; 10 to 23) and His to atrial intervals (HA) (14 +/- 4 ms; 10 to 20) with an identical atrial activation sequence for both right BBB or normal QRS tachycardia complexes. In contrast, all 5 patients with left BBB showed a decrease in the VA (-18 +/- 11 ms; 10 to 36) with unchanged HA comparing left BBB to normal QRS patterns during AVNRT. The magnitude of prolongation of the His to ventricular interval (HV) during left BBB (19 +/- 12 ms; 10 to 40) was nearly identical to the decrease in the VA. In conclusion, prolongation of VA and HA with unchanged HV in patients with AVNRT and right BBB suggests that right BBB is due to a block in the fibers in close proximity to the His recording site. The data suggest that fibers in the His bundle are predestined to activate the right bundle branch, and in AVNRT the lower turnaround point may be within the His bundle.

Adult↗
PubMed2003

Optimizing the detection of bidirectional block across the flutter isthmus for patients with typical isthmus-dependent atrial flutter.

The purpose of this study was to show that multipolar electrographic recordings along the subeustachian isthmus (SI) can better differentiate slow conduction from complete isthmus block after atrial flutter ablation, leading to a lower incidence of recurrent atrial flutter (Afl). Despite the presence of various techniques to identify bidirectional conduction block (BDB) after isthmus ablation for typical Afl, several studies, including a report from a national registry, suggest that radiofrequency ablation is still associated with a 15% recurrence rate. Thus, techniques that can distinguish slow conduction from complete isthmus block have the potential for reducing long-term recurrences. We evaluated patients who underwent radiofrequency ablation for typical isthmus-dependent Afl. Patients were separated into 2 groups. Group A underwent assessment of BDB with conventional methods. In group B, BDB was assessed by placing a multipolar catheter along the floor of the SI, pacing adjacent to the line of radiofrequency application, and assessing electrographic activation on either side. One hundred thirty-one cases of Afl ablation were analyzed (86 in group A, 45 in group B). Over a mean follow-up period of 17 months, recurrence rates of Afl were 16.5% in group A and 4.3% in group B (p = 0.043). Thus, assessment of BDB by placement of a multipolar catheter across the SI after ablation of typical Afl is associated with a significant reduction in long-term recurrence of Afl.

Aged↗
PubMed2003

Mechanism of conversion of atypical right atrial flutter to atrial fibrillation.

The purpose of this study was to explore the mechanisms of conversion from atypical atrial flutter (AFL) to atrial fibrillation (AF), and the long-term results of cavotricuspid isthmus ablation in these patients. We retrospectively reviewed the records of 221 patients with typical AFL referred to our hospital for ablation. A total of 25 patients had atypical AFL, and cavotricuspid isthmus ablation was performed in 23 with isthmus-dependent atypical AFL, as well as in 180 patients with typical counterclockwise and/or clockwise AFL. In all, 13 spontaneous transitions from atypical AFL to AF were documented in 11 of 17 patients. Before AF, a pattern of lower loop reentry was observed in 11 of 13 patients (85%) and upper loop reentry in 3 (1 had both). Multiple early breaks along the tricuspid annulus during AFL were noted in 6 of 13 patients (46%). Among the 13 transitions, discrete atrial premature complexes before AF were found in 5 patients with lower loop reentry and in 1 with upper loop reentry (46%). In the remaining patients, a more rapid atrial rhythm was involved in the development of AF with a pulmonary venous focus in 2. In some cases, additional "breaks" in the functional line of block occurred before the development of AF. There was a significant increased incidence of AF (68%) in those with atypical AFL compared with those with typical AFL (38%) (p = 0.004). After a mean follow-up of 28 +/- 9 months for the atypical group and 18 +/- 11 months for the typical group, the AF recurrence rate was similar (57% vs 48%, p = 0.4). Discrete atrial premature complexes or atrial tachycardia may initiate AF either directly or by producing further breaks in lines of functional block. Bidirectional cavotricuspid isthmus block is associated with cure or control of AF in approximately 50% of patients with AFL.

Atrial Fibrillation↗
PubMed2003

Evaluation of transisthmus conduction interval in predicting bidirectional block after ablation of typical atrial flutter.

OBJECTIVE: To determine whether the extent of prolongation of the transisthmus interval after ablation predicts complete bidirectional block. METHODS: Since 1996 to 2002, 30 consecutive patients underwent ablation procedures for isthmus-dependent atrial flutter. There were 23 males and 7 females [mean age (47.85 +/- 9.35) years]. With the use of fluoroscopic view of anatomy, radiofrequency ablation was performed during coronary sinus pacing at a cycle length of 600 ms. RESULTS: Bidirectional block was achieved with ablation in 29 (97%) of 30 patients. The transisthmus intervals before ablation and after complete transisthmus block were (73.82 +/- 13.01) ms and (140.47 +/- 20.48) ms, respectively, in the clockwise direction (P < 0.0001), and (77.63 +/- 8.36) ms and (138.17 +/- 15.55) ms, respectively, in the counterclockwise direction (P < 0.0001). A period of incomplete isthmus block was observed during 17 (58%) of the 29 ablation procedures. The clockwise transisthmus intervals during incomplete block [(107.65 +/- 21.33) ms] were (45.5 +/- 8.7)% longer than the baseline transisthmus intervals. An increase in the transisthmus interval by > or = 50% in both directions after ablation predicted complete bidirectional block with 100.0% sensitivity and 83.3% specificity. The positive and negative predictive values were 90.6% and 100.0%, respectively. The diagnostic accuracy of a > or = 50% prolongation in the transisthmus interval was 83.3%. CONCLUSION: The analysis of transisthmus interval is a valuable method for determining complete bidirectional isthmus block.

Atrial Flutter↗
PubMed2002

Clinical and electrophysiologic characteristics of left septal atrial tachycardia.

OBJECTIVES: It was the purpose of this study to define the electrophysiologic (EP) identity of left septal atrial tachycardia (AT). BACKGROUND: The clinical and EP characteristics of this particular type of arrhythmia have not been fully described. METHODS: A total of 120 patients with AT underwent invasive EP evaluation. Five patients (two men and three women; mean age 49 +/- 15 years) with left septal AT were identified. Mapping of the right and left atrium was performed using conventional electrode catheters (five patients) and a three-dimensional electroanatomic mapping system (three patients) followed by radiofrequency (RF) ablation at the earliest site of local endocardial activation. RESULTS: Five tachycardias with a mean cycle length of 320 +/- 94 ms were mapped, and the earliest endocardial electrogram occurred 22 +/- 10 ms before the onset of the surface P-wave. Three left septal ATs were found to be originating from the left inferoposterior atrial septum and two from the left midseptum. During tachycardia, positive (three patients), biphasic negative-positive deflection (one patient), or isoelectric (one patient) P waves were recorded in lead V(1). The inferior leads demonstrated a positive or biphasic P-wave morphology in four of five patients (80%). Four patients were given both adenosine and verapamil during AT. In three of four patients, verapamil successfully terminated AT after adenosine had failed. Adenosine successfully terminated AT in one of four patients. Successful RF ablation was performed in all patients (mean 2.2 +/- 1.7 RF applications) without affecting atrioventricular conduction properties. No recurrence of AT was observed after a mean follow-up of 14 +/- 8 months. CONCLUSION: Left septal AT ablation is safe and effective. There was no consistent P-wave morphology associated with this particular type of AT. This arrhythmia appears to be resistant to adenosine and moderately responsive to calcium antagonists.

Adenosine↗