Ablation characteristics and incidence of steam pops with a novel, surface temperature-controlled ablation system in an ex vivo experimental model

BACKGROUND

A novel irrigation catheter (QDOT MICRO™) has been introduced, which enables a surface temperature-controlled ablation combined with tip cooling. However, the detailed description of its complex behavior and effect on the incidence of pops and lesion formation remains elusive. This study aimed to systematically investigate the ablation characteristics, feedback behavior, and incidence of steam pops in a simplified ex vivo swine model.

METHODS

Using swine ventricular tissue perfused with saline at 37°C, we systematically created lesions with 4×3 combinations of the wattage (20, 30, 40, and 50 W) and contact force (CF, 10, 30, and 50 g). Ablation was continued for either 120 s or until a steam pop occurred and repeated 10 times with each setting. The lesion geometry, ablation index, feedback dynamics, and conditions underlying the steam pops were measured and analyzed.

RESULTS

Steam pops occurred particularly frequently in combinations of a low CF and high power (10 g vs. 30 g+50 g [p < .0001]; 40 W+50 W vs. 20 W+30 W [p < .0001]). Failure to activate a feedback process was associated with a 5.1 times higher incidence of steam pops (21/109 vs.11/11, [95% CI 3.499-7.716], p < .0001). The wattage feedback was particularly evident with a high CF (30 and 50 g) and high initial wattage (40 and 50 W). The average delivered wattage at 27 W predicted the occurrence of steam pops.

CONCLUSION

The temperature-controlled ablation with the QDOT MICRO™ demonstrated a complex feedback behavior, which contributed to a reduced incidence of steam pops and prolonged lead time to the pops.

Characteristics and optimal ablation settings of a novel, contact-force sensing and local impedance-enabled catheter in an ex vivo perfused swine ventricle model

BACKGROUND

Local impedance (LI) has emerged as a new technology that informs on electrical catheter-tissue coupling during radiofrequency (RF) ablation. Recently, IntellaNav StablePoint, a novel LI-enabled catheter that equips contact force (CF) sensing, has been introduced. Although StablePoint and its predecessor IntellaNav MiFi OI share the common technology that reports LI, distinct mechanics for LI sensing between the two products raise a concern that the LI-RF lesion formation relationship may differ.

METHODS

In an ex vivo swine cardiac tissue model, we investigated the initial level and range of a reduction in LI during a 60-s RF ablation and the resultant lesion characteristics at nine combinations of three energy power (30, 40, and 50 W) and CF (10, 30, and 50 g) steps. Correlations and interactions between CF, LI, wattage, and formed lesions were analyzed. Incidence of achieving LI drop plateau and that of a steam pop were also determined.

RESULTS

Positive correlations existed between CF and initial LI, CF and absolute/relative LI drop, CF and lesion volume, and LI drop and lesion volume. At the same LI drop, wattage-dependent gain in lesion volume was observed. Steam pops occurred in all CF steps and the prevalence was highest at 50 W. LI drop predicted a steam pop with a cutoff value at 89Ω.

CONCLUSION

In StablePoint, wattage crucially affects LI drop and lesion volume. Because 30 W ablation may by underpowered for intramural lesion formation and 50 W often resulted in a steam pop, 40 W appears to achieve the balance between the safety and efficacy.

Ultrahigh density atrio-ventricular dual-chamber mapping as a next generation tool for ablation of accessory pathways

INTRODUCTION

Detailed three-dimensional (3D) mapping has been useful for effective radiofrequency catheter ablation. The Rhythmia system can create atrio-ventricular dual-chamber mapping, which reveals the atrial and ventricular potentials all at once in the same map. The aim of this study was to investigate the utility of mapping the atrium and ventricle simultaneously with a high-density 3D mapping system for the ablation of accessory pathways (AP).

METHODS

From July 2015 to August 2020, 111 patients underwent ablation of APs. Dual-chamber maps were created in 50 patients (median age 15 [10-54], 32 male [64.0%]), while 61 patients underwent radiofrequency (RF) ablation with conventional single-chamber 3D maps. The background characteristics and procedural details were compared between the dual-chamber mapping group and the conventional single-chamber mapping group.

RESULTS

The number of RF applications (median [IQR]; 1.0 [1.0-3.0] vs. 3.0 [1.0-6.0], p = .0023), RF time (median [IQR], s; 9.2 [2.0-95.7] vs. 95.6 [4.1-248.7], p = .0107), and RF energy (median [IQR], J; 248.4 [58.7-3328.2] vs. 2867.6 [134.2-7728.4], p = .0115) were significantly lower in the dual-chamber group. The fluoroscopy time (median [IQR], min; 19.9 [14.2-26.1] vs. 26.5 [17.7-43.4], p = .0025) and fluoroscopy dose (median [IQR], mGy; 52.5 [31.3-146.0] vs. 119.0 [43.7-213.5], p = .0249) were also significantly lower in the dual-chamber than single-chamber mapping group.

CONCLUSION

The dual-chamber mapping was useful for ablating accessory pathways and reducing the number of RF applications, total RF energy, and radiation exposure as compared with traditional mapping techniques.

Transvenous lead performance of implantable cardioverter-defibrillators and pacemakers

BACKGROUND

After the reports of recalled leads, several technological improvements have been introduced and the durability of implantable cardioverter defibrillator (ICD) leads has improved. The incidence of lead failures is now less than in the previous studies. However, there are few reports that have shown the long-term durability of ICD leads as compared to pacemaker (PM) leads. This study analyzed the medium to long-term performance of transvenous ICD leads as compared to PM leads.

METHODS

We retrospectively studied 1227 cases from April 2007 to December 2017 who underwent an initial transvenous ICD or PM implantation. The number of lead failures and patient background characteristics were analyzed.

RESULTS

During a median 3-3.5 years follow up period, 1 (0.3%) ICD lead and 18 (2.4%) PM leads failed. The incidence of lead failures was significantly higher in the PM group than ICD group (p = .019). Males were associated with a higher incidence of lead failures in the PM group.

CONCLUSION

Since the era of recalled ICD leads, the durability of ICD leads has remarkably improved and the incidence of lead failures with non-recalled ICD leads has been less than that for PM leads.

Differential Atrial Pacing to Detect Reconnection Gaps After Pulmonary Vein Isolation in Atrial Fibrillation

High-resolution mapping is useful to identify reconnection gaps in the pulmonary vein after pulmonary vein isolation for atrial fibrillation. However, it is sometimes difficult to differentiate pulmonary vein potentials from far-field potentials because of very low amplitudes. Our purpose was to evaluate the usefulness of a novel differential atrial pacing method to differentiate reconnected pulmonary vein potentials from isolated pulmonary vein potentials. This retrospective observational study included 34 patients with atrial fibrillation (22 men; mean age, 64 ± 14 years; 28 with paroxysmal atrial fibrillation) who underwent radiofrequency or cryoballoon ablation. Following pulmonary vein isolation, we created a high-resolution activation map during pacing from both the coronary sinus and left atrial appendage. We compared the characteristics of the pulmonary vein potentials and the pattern of activation between the reconnected and isolated pulmonary veins. We analyzed 131 pulmonary veins and found reconnections in 41 pulmonary veins (R group); 90 pulmonary veins had no reconnection (NR group). The R group had a significantly shorter distance between the earliest pulmonary vein activation sites in both activation maps, compared with the NR group (5.22 ± 0.53 mm versus 17.08 ± 0.36 mm, respectively; P < 0.0001). The amplitude of the pulmonary vein potentials was higher in the R group versus the NR group (0.61 ± 0.05 mV versus 0.04 ± 0.03 mV, respectively; P < 0.0001). Six gaps (14%) in the R group that were unrecognized using a conventional method were identified using our novel method. In conclusion, differential atrial pacing was useful to identify pulmonary vein reconnection gaps during ablation using a novel high-resolution mapping system.

Uterine intravenous leiomyomatosis with an isolated large metastasis to the right atrium: a case report

Background

An intravenous leiomyomatosis is a special type of uterine leiomyoma characterized by the formation of benign leiomyomatous tissue within the vascular wall. Although histologically benign, intracardiac metastasis can lead to circulatory failure, and death, if untreated. Herein, we report on a case of a uterine intravenous leiomyomatosis with an isolated large adherent metastasis in the right atrium of the heart.

Case Presentation

A 52-year-old Japanese woman sought medical attention at our hospital for lower abdominal pain. A 27-cm uterine mass was detected on clinical imaging, with a 78 × 47-mm mass in the right atrium detected on preoperative echocardiography. Intracardiac mass resection and tricuspid annuloplasty were performed as the first-stage surgery. The pedicle of the tumor was adherent to the wall of the atrium. On histological examination, the tumor was found to consist of spindle-shaped cells with eosinophilic cytoplasm, without atypia, but with a myxoid change, and rich microvascularization of the pedicle. Total abdominal hysterectomy was performed as the second-stage surgery, with confirmation of the diagnosis as uterine intravenous leiomyomatosis with an isolated metastasic lesion to the right atrium. There has been no evidence of tumor recurrence in the 15 months since surgery.

Conclusion

We report a unique case in which a large right atrial leiomyoma was identified following a uterine intravenous leiomyomatosis. Our case exemplifies that intravenous leiomyomatosis metastatic tumors have the potential to grow via their vascularization.

88 Severe tricuspid regurgitation due to papillary muscle rupture: A rare complication of anterior myocardial infarction and ventricular septal perforation

INTRODUCTION

Papillary muscle rupture (PMR) of the mitral valve is a fatal complication of acute myocardial infarction (MI). As a complication of anterior MI, PMR of the tricuspid valve is extremely rare. We experienced a case of acute anterior MI complicated with tricuspid PMR and ventricular septal perforation (VSP).

REPORT

An 85-year-old woman was admitted with general fatigue and appetite loss. Her consciousness was alert, but she was pale, and had cold extremities. Her blood pressure was 74/62 mmHg, and pulse was 99/min. There was no leg edema. Pan systolic regurgitant murmur (Levine III/VI) was audible at the lower left sternal border. Her oxygen saturation was 86% under room air. Electrocardiogram revealed ST segment elevation and QS pattern in V1 to V3. Transthoracic echocardiography revealed dyskinesis of the apical anterior septum, VSP with bidirectional shunt, and severe pulmonary hypertension. Left ventricular ejection fraction was preserved (58%). The anterior tricuspid leaflet was flail due to PMR, resulting in severe tricuspid regurgitation and right ventricular dilatation. Coronary angiography revealed a single vessel disease of the left anterior descending artery (LAD). We recommended surgical treatment, and transferred her to another hospital.

DISCUSSION

Common causes of tricuspid PMR are infective endocarditis and chest trauma. Right ventricular infarction, usually caused by right coronary artery (RCA) occlusion, may cause tricuspid PMR. In our case, however, tricuspid PMR was complicated with anterior MI. The tricuspid anterior, posterior, and septal leaflets are attached to anterolateral RV wall, inferior septum, and infundibular septum, respectively, via papillary muscles. Right ventricular branches and septal branches of the RCA usually supply these papillary muscles. Anterior leaflet PMR in this case was possibly due to anomalous blood supply of anterolateral RV wall by the right ventricular branches of the LAD. Right ventricular overload due to large VSP shunt elevated RV diastolic pressure and right atrial pressure, and might worsen ischemia of the RV wall.

Abstract 88 Figure. severe TR & shunt flow through VSP

Relationship between the ablation index, lesion formation, and incidence of steam pops

BACKGROUND

The ablation index (AI) is reported to be useful for a durable pulmonary vein isolation (PVI). However, there have been no studies investigating the relationship between the power, contact force (CF), AI, and steam pops.

METHODS

Using an in vitro model, ablation energy was delivered until a steam pop occurred and the time to the steam pop and AI when the steam pop occurred were measured. The experiment was performed with a combination of various powers (20, 30, 40, and 50 W) and contact forces (CFs) (10, 30, and 50 g) 20 times for each setting. The analysis consisted of two protocols. The first protocol was a comparison between the ablation power and several parameters under the same CF (10, 30, and 50 g). The second protocol was a comparison between the CF and several parameters under the same power (20, 30, 40, and 50 W). The correlation between the lesion formation and ablation parameters was evaluated.

RESULTS

The AI value when steam pops occurred varied depending on the ablation settings. All AI median values were <500 under an ablation power of 50 W. On other hand, the median ablation time up to the steam pop was more than 46 seconds, but all median values of the AI were more than 550 under an ablation with 20 W.

CONCLUSIONS

The AI cannot predict steam pops. A low power and long duration ablation could obtain a high AI value. However, high-power ablation could not obtain a high AI value because of an early occurrence of steam pops.

Establishment of a quantitative and qualitative analysis and isolation method for tetracyclic iridoids from Morinda lucida Bentham leaves

A new high performance liquid chromatography (HPLC) method has been established for quantitative and qualitative analysis of three tetracyclic iridoids: ML-2-3 (1), molucidin (2), and ML-F52 (3), which are responsible for anti-trypanosomal and anti-leishmanial activities of Morinda lucida Bentham leaves. Separation of 1-3 from dried 80% aqueous (aq.) ethanol extract was achieved on a reversed-phase cholester column packed with cholesteryl-bonded silica using an acetonitrile-0.1% aq. formic acid mobile phase system. Ultraviolet-visible (UV-VIS) spectroscopy was employed for detection of compounds, and their contents were determined by measuring absorbance at 254 nm. Depending on the above system, several factors potentially affecting the concentration of tetracyclic iridoids were evaluated resulting in several variation on plant organs, seasonality, variation between individual trees, and branch positions within the trees. Moreover, we developed a simple, quick, and effective method for tetracyclic iridoid isolation from M. lucida leaves that consisted of extraction by sonication into 80% aq. ethanol, basic hydrolysis, acid neutralization, liquid-liquid extraction into an organic solvent, and reverse phase open column chromatography. Employing this method, we have succeeded to obtain 1 as a colorless crystal yielding of 0.23%, which was 28 times higher than that of previous isolation method. Setting up methodology in this paper may be important for future in vitro and in vivo studies of tetracyclic iridoids and moreover for their applications in new drug design and development.

Guideline from Japanese Society of Echocardiography: 2018 focused update incorporated into Guidance for the Management and Maintenance of Echocardiography Equipment

Echocardiography plays a pivotal role as an imaging modality in the modern cardiology practice. Information derived from echocardiography is definitely helpful for a patient care. The Japanese Society of Echocardiography has promoted echocardiography for a routine clinical and research use. One of the missions of the Society is to provide information that is useful for high-quality examinations. To ensure it, we believe equipment in good conditions and a comfortable environment are important for both a patient and an examiner. Thus, the Committee for Guideline Writing, the Japanese Society of Echocardiography published brief guidance for the routine use of echocardiography equipment in 2015. Recently, the importance of international standardization has been emphasized in the medical laboratories. Accordingly, the committee has revised and updated our guidance for the routine use of echocardiography equipment.

Real-time observation of pathophysiological processes during murine experimental Schistosoma japonicum infection using high-resolution ultrasound imaging

BACKGROUND

Hepatosplenic lesion formation is one of the typical clinical symptoms of schistosomiasis japonica. Although it is established that circum-oval granuloma formation mediated by T lymphocytes is the key event triggering the formation of hepatic lesions, the time-course kinetics of disease progression remains to be fully elucidated.

METHODS

The real-time process of the pathophysiology of schistosomiasis japonica from the early to late clinical phase was non-invasively observed in a murine experimental infection model using high-resolution ultrasonography. Together with clinical parameters, including body weight and the levels of serum markers of hepatic damage or fibrosis, ultrasonography was used to assess changes in the liver parenchyma and diameter of the portal vein and portal blood flow velocity. In parallel, parasitological parameters were observed, including egg number in the feces and maturation of parasites.

RESULTS

Abnormal high-echo spot patterns in the liver parenchyma, reflecting hepatic fibrosis in ultrasonography, appeared in the liver at 4 weeks post-infection and the pattern became more enlarged and severe over time. This finding was concordant with parasite maturation and initial egg excretion. The serum M2BPGi level markedly increased from 8 weeks post-infection, suggesting sharp deterioration of hepatic fibrosis. At the same time, the diameter of the portal vein, reflecting portal hypertension, became enlarged and reached the peak level at 8 weeks post-infection. Ascites were apparent around the spleen at 9 weeks post-infection, and dilatation of the splenic vein was noted at 10 weeks post-infection. Live adult worms seemed to be detected in the portal vein at 4 weeks post-infection by ultrasonography.

CONCLUSIONS

We obtained real-time imaging of the development of hepatosplenic lesions of schistosomiasis japonica in mice. The time-course kinetics of the onset, development, and modulation of each symptom was uncovered. These results are expected to provide new clues for understanding the pathophysiology of human schistosomiasis japonica.

Long-Term Survival on Medical Therapy Alone after Blunt-Trauma Aortic Regurgitation: Report of a New Case with Summary of 95 Others

Aortic regurgitation resulting from blunt chest trauma has been reported only 95 times, to our knowledge. The noncoronary and right coronary cusps are the cardiac structures most often injured. Although the aortic leaflets can appear to be undamaged after nonpenetrating trauma, they can have pathologic abnormalities and insufficient function. Some cases of posttraumatic aortic regurgitation progress slowly. Aortic valve replacement is the optimal treatment. We present the case of a then-62-year-old man who has lived more than 5 years after blunt-trauma aortic regurgitation. His is the only case of long-term survival on medical therapy alone among the 96 cases summarized in this report.

Nuclear hormone receptor LXRα inhibits adipocyte differentiation of mesenchymal stem cells with Wnt/beta-catenin signaling

Nuclear hormone receptor liver X receptor-alpha (LXRα) has a vital role in cholesterol homeostasis and is reported to have a role in adipose function and obesity although this is controversial. Conversely, mesenchymal stem cells (MSCs) are suggested to be a major source of adipocyte generation. Accordingly, we examined the role of LXRα in adipogenesis of MSCs. Adult murine MSCs (mMSCs) were isolated from wild-type (WT) and LXR-null mice. Using WT mMSCs, we further generated cell lines stably overexpressing GFP-LXRα (mMSC/LXRα/GFP) or GFP alone (mMSC/GFP) by retroviral infection. Confluent mMSCs were differentiated into adipocytes by the established protocol. Compared with MSCs isolated from WT mice, MSCs from LXR-null mice showed significantly increased adipogenesis, as determined by lipid droplet accumulation and adipogenesis-related gene expression. Moreover, mMSCs stably overexpressing GFP-LXRα (mMSC/LXRα/GFP) exhibited significantly decreased adipogenesis compared with mMSCs overexpressing GFP alone (mMSC/GFP). Since Wnt/beta-catenin signaling is reported to inhibit adipogenesis, we further examined it. The LXR-null group showed significantly decreased Wnt expression accompanied by a decrease of cellular beta-catenin (vs WT). The mMSC/LXRα/GFP group exhibited significantly increased Wnt expression accompanied by an increase of cellular beta-catenin (vs mMSC/GFP). These data demonstrate that LXRα has an inhibitory effect on adipogenic differentiation in mMSCs with Wnt/beta-catenin signaling. These results provide important insights into the pathophysiology of obesity and obesity-related consequences such as metabolic syndrome and may identify potential therapeutic targets.

A rare case of fungal endocarditis caused by Candida glabrata after completion of antibiotic therapy for Streptococcus endocarditis

We present the rare case of a 76-year-old female with infective endocarditis (IE) caused by Candida glabrata. Immediately before developing the present infection, she developed IE with vegetation on the mitral annular calcification, which was caused by Streptococcus mitis and successfully treated with penicillin-G and gentamicin. However, her fever recurred, and she developed disseminated intravascular coagulation. Blood culture revealed C. glabrata, and echocardiography revealed new vegetation on the mitral valve. After 4 weeks of treatment with micafungin, prosthetic valve replacement was performed, followed by additional administration of micafungin for 4 weeks (total of 8 weeks). No relapse at 9 months after surgery has been observed. C. glabrata endocarditis is extremely rare and difficult to manage. Our case and review of past reported cases suggest that early diagnosis and initiation of treatment contribute to good prognosis of C. glabrata endocarditis.

Bioprosthetic tricuspid valve replacement in carcinoid heart disease from primary ovarian carcinoid tumor

Carcinoid heart disease (CHD) commonly occurs in association with primary gastrointestinal tract carcinoid tumors with hepatic metastases. Unlike primary gastrointestinal tract carcinoid tumors, primary ovarian carcinoid tumors may cause CHD without hepatic metastases, accounting for only 0.3 % of all carcinoid tumors. Only 37 cases of CHD from primary ovarian carcinoid tumors have been reported. We present a case of CHD in which tricuspid valve thickening and shortening led to reduced valve mobility with the resulting severe tricuspid regurgitation. Considering these characteristics of an abnormal tricuspid valve, we suspected CHD, but prosthetic valve replacement was performed without sufficient systemic examination before surgery. Two years after valve replacement, the patient underwent excision of a mass in the lower abdomen, which was diagnosed as an ovarian carcinoid tumor by histopathological examination. The patient has been observed for more than 3 years after tricuspid valve replacement. She has not experienced bioprosthetic valve leaflet degeneration or dysfunction, although it has been reported that bioprosthetic valves may degenerate in patients with carcinoid tumors. Sufficient systemic examinations should be performed to explore the cause of disease.

Effect of lesional differences in prolapsed leaflets on clinical outcomes in patients with mitral valve prolapse

BACKGROUND

Mitral valve prolapse (MVP) is usually benign, although serious complications may occur. It remains unclear whether the region of prolapsed mitral leaflets might affect prognosis. The aim of this study was to investigate lesional differences of clinical courses of MVP.

METHODS AND RESULTS

We retrospectively investigated 128 MVP patients who had been followed up for for a mean of 56.4 months. They were classified into prolapse of the anterior mitral leaflet (AML, n = 59), posterior mitral leaflet (PML, n = 47), or both leaflets (AML & PML, n = 22). Echocardiographic and clinical data were examined from medical records. Average time to clinical events; MV surgery, new onset of atrial fibrillation (AF), echocardiographic evidence of new chordal rupture, and worsening of mitral regurgitation severity were all significantly shorter in PML prolapse than in those with AML or AML & PML prolapses. Increases in the left ventricular dimensions and estimated pulmonary arterial systolic pressures were significantly larger in PML prolapse, compared with AML or AML & PML prolapses. A subanalysis of PML prolapse revealed that new chordal rupture tended to be more frequent in middle scallop prolapse (48%) compared with lateral and medial scallops (18%). In contrast, new onset of AF tended to occur in lateral and medial scallop prolapses (44%) compared with middle scallop prolapse (20%).

CONCLUSIONS

PML prolapse patients had a poor outcome, compared with AML or AML & PML prolapse patients. Precise regional evaluation of the prolapsed leaflets may predict cardiac complications in MVP.

Biomatrices and biomaterials for future developments of bioprinting and biofabrication

The next step beyond conventional scaffold-based tissue engineering is cell-based direct biofabrication techniques. In industrial processes, various three-dimensional (3D) prototype models have been fabricated using several different rapid prototyping methods, such as stereo-lithography, 3D printing and laser sintering, as well as others, in which a variety of chemical materials are utilized. However, with direct cell-based biofabrication, only biocompatible materials can be used, and the manufacturing process must be performed under biocompatible and physiological conditions. We have developed a direct 3D cell printing system using inkjet and gelation techniques with inkjet droplets, and found that it had good potential to construct 3D structures with multiple types of cells. With this system, we have used alginate and fibrin hydrogel materials, each of which has advantages and disadvantages. Herein, we discuss the roles of hydrogel for biofabrication and show that further developments in biofabrication technology with biomatrices will play a major part, as will developments in manufacturing technology. It is important to explore suitable biomatrices as the next key step in biofabrication techniques.

Mesenchymal stem cells differentiate into renin-producing juxtaglomerular (JG)-like cells under the control of liver X receptor-alpha

Renin is a key enzyme for cardiovascular and renal homeostasis and is produced by highly specialized endocrine cells in the kidney, known as juxtaglomerular (JG) cells. The nature and origin of these cells remain as mysteries. Previously, we have shown that the nuclear hormone receptor liver X receptor-alpha (LXRalpha) is a major transcriptional regulator of the expression of renin, c-myc, and other genes involved with growth/differentiation. In this study we test the hypothesis that LXRalpha plays an important role not only in renin expression but also in renin-containing cell differentiation, specifically from the mesenchymal stem cell (MSC), which may be the origin of the JG cell. Indeed, our data demonstrated that LXRalpha activation by its ligands or cAMP stimulated renin gene expression in both murine and human MSCs. Furthermore, sustained cAMP stimulation of murine MSCs overexpressing LXRalpha led to their differentiation into JG-like cells expressing renin and alpha-smooth muscle actin. These MSC-derived JG-like cells contained renin in secretory granules and released active renin in response to cAMP. In conclusion, the activation of LXRalpha stimulates renin expression and induces MSCs differentiation into renin-secreting, JG-like cells. Our results suggest that the MSC may be the origin of the juxtaglomerular cell and provide insight into novel understanding of pathophysiology of the renin-angiotensin system.

Biochemical characterization of plasma-derived tissue factor pathway inhibitor: post-translational modification of free, full-length form with particular reference to the sugar chain

BACKGROUND

Tissue factor pathway inhibitor (TFPI) is a physiological protease inhibitor that inhibits the initial reactions of the extrinsic blood coagulation pathway. Most TFPI in human plasma is associated with lipoproteins; however, the most functionally active form is thought to be the free, full-length form (f-pTFPI). Cell culture derived TFPI and recombinant TFPI (rTFPI) exhibit variations in their respective anticoagulant activity, which may be caused by post-translational modifications, such as the frequent differences in sugar chain structures among recombinant proteins. Sugar chain structures in rTFPI expressed in Chinese hamster ovary (CHO) cells have been reported previously, but those of plasma TFPI have not been.

OBJECTIVES

To purify f-pTFPI and analyze the sugar chain structures.

RESULTS AND CONCLUSION

f-pTFPI was purified to homogeneity from blood plasma using a combination of anion-exchange, heparin affinity, immunoaffinity, and reversed-phase chromatographies, resulting in a yield of 76%. f-pTFPI showed a partially phosphorylated glycoprotein comprising a total of 276 amino acids by peptide mapping. The sugar chain structures were analyzed by two-dimensional sugar mapping combined with exoglycosidase digestion of the pyridylamino sugar chains and the following results were obtained. (Sialyl) Galbeta1-3GalNAc was linked to Thr(175), partially to Thr(14) and Ser(174); sialyl complex-type sugar chains to Asn(117) and Asn(167), whereas Asn(228) was not glycosylated. Neuraminidase-resistant acidic sugar chains including sulfated sugar chains were not observed significantly. The protease inhibitory activities of f-pTFPI towards activated factor (F) X and tissue factor-activated FVII complex were identical to those of full-length rTFPI expressed in CHO cells.

A real-time three-dimensional echocardiographic quantitative analysis of left atrial function in left ventricular diastolic dysfunction

The evaluation of left ventricular diastolic function provides important information about hemodynamics and has prognostic implications for various cardiac diseases. In particular, left atrial (LA) volume is an increasingly significant prognostic biomarker for diastolic dysfunction. The aim of this study was to assess left ventricular diastolic function by measuring changes in LA volume using real-time 3-dimensional echocardiography. The 106 subjects were divided into 4 groups (normal, impaired relaxation, pseudonormal, and restrictive) on the basis of diastolic function, as assessed by transmitral flow patterns. LA volume was measured during a heart cycle using real-time 3-dimensional echocardiography. LA stroke volume (maximum LA volume - minimum LA volume) and the LA ejection fraction (LA stroke volume/maximum LA volume x 100) were calculated using Doppler imaging to assess their correlation with other parameters used to evaluate left ventricular diastolic function, including transmitral flow pattern and early diastolic mitral annular velocity (E'). LA volume indexed to body surface area was dilated in subjects with left ventricular diastolic dysfunction, whereas the LA ejection fraction was lower. The maximum LA volume, minimum LA volume, and LA ejection fraction were significantly different between each group, and each was significantly correlated with the ratio of early diastolic transmitral flow velocity (E) to E' (E/E'). The LA ejection fraction correlated best with E/E' (r = -0.68, p <0.0001). In conclusion, cyclic changes in LA volume could be measured using real-time 3-dimensional echocardiography, and measuring LA function with this method may be a viable alternative for the accurate assessment of left ventricular diastolic function.

A femtosecond laser pacemaker for heart muscle cells

The intracellular effects of focused near-infrared femtosecond laser irradiation are shown to cause contraction in cultured neonatal rat cardiomyocytes. By periodic exposure to femtosecond laser pulse-trains, periodic contraction cycles in cardiomyocytes could be triggered, depleted, and synchronized with the laser periodicity. This was observed in isolated cells, and in small groups of cardiomyocytes with the laser acting as pacemaker for the entire group. A window for this effect was found to occur between 15 and 30 mW average power for an 80 fs, 82 MHz pulse train of 780 nm, using 8 ms exposures applied periodically at 1 to 2 Hz. At power levels below this power window, laser-induced cardiomyocyte contraction was not observed, while above this power window, cells typically responded by a high calcium elevation and contracted without subsequent relaxation. This laser-cell interaction allows the laser irradiation to act as a pacemaker, and can be used to trigger contraction in dormant cells as well as synchronize or destabilize contraction in spontaneously contracting cardiomyocytes. By increasing laser power above the window available for laser-cell synchronization, we also demonstrate the use of cardiomyocytes as optically-triggered actuators. To our knowledge, this is the first demonstration of remote optical control of cardiomyocytes without requiring exogenous photosensitive compounds.

A case report of surgical correction for congenital mitral regurgitation with subvalvular apparatus abnormality

We report a successful complex mitral valve plasty using port access minimally invasive cardiac surgery for congenital mitral regurgitation that presented as an abnormality of the subvalvular apparatus. A 16-year-old male patient received a diagnosis of mitral regurgitation resulting from tethering of the anterior mitral leaflet and posterior mitral leaflet caused by an abnormality in papillary muscle insertion and a hypoplastic chordae tendineae. The posterior leaflet was closely tethered to the tips of the papillary muscle with essentially no chordae tendineae. The flexibility of the leaflet was restored by surgically removing the abnormal chordae, and reconstruction of chordae tendinae of the anterior leaflet was carried out using three loops and of the posterior leaflet using one loop with a loop technique method. As an additional procedure for persistent regurgitation, an edge-to-edge technique to the posterior commissure side was performed, after which the mitral regurgitation disappeared.