Aveir VR real-world performance and chronic pacing threshold prediction using mapping and fixation electrical data

AIMS

Aveir VR performance and predictors for its pacing threshold (PCT) in a real-world cohort were investigated.

METHODS

Electrical measurements at various stages of an Aveir VR implant were prospectively collected. Predictors for 3-month PCT were studied. A retrospective cohort of consecutive 139 Micra implants was used to compare the PCT evolution. High PCT was defined as ≥1.5 V, using a pulse width of 0.4 ms for Aveir and 0.24 ms for Micra. Excellent PCT was defined as ≤0.5 V at the respective pulse width.

RESULTS

Among the 123 consecutive Aveir VR implant attempts, 122 (99.2%) were successful. The majority were of advanced age (mean 79.7) and small body size (mean BSA 1.60). Two patients (1.6%) experienced complications, including one pericardial effusion after device reposition and one intraoperative device dislodgement. Eighty-eight patients reached a 3-month follow-up. Aveir 3-month PCT was correlated with impedance at mapping (P = 0.015), tether mode (P < 0.001), end-of-procedure (P < 0.001), and mapping PCT (P = 0.035), but not with PCTs after fixation (P > 0.05). Tether mode impedance >470 ohms had 88% sensitivity and 71% specificity in predicting excellent 3-month PCT. Although it is more common for Aveir to have high PCT at end of procedure (11.5% for Aveir and 2.2% for Micra, P = 0.004), the rate at 3 months was similar (2.3% for Aveir and 3.1% for Micra, P = 1.000).

CONCLUSION

Aveir VR demonstrated satisfactory performance in this high-risk cohort. Pacing thresholds tend to improve to a greater extent than Micra after implantation. The PCT after fixation, even after a waiting period, has limited predictive value for the chronic threshold. Low-mapping PCT and high intraoperative impedance predict chronic low PCT.

Addressing the risk and management of cardiometabolic complications in prostate cancer patients on androgen deprivation therapy and androgen receptor axis-targeted therapy: consensus statements from the Hong Kong Urological Association and the Hong Kong Society of Uro-Oncology

Background

Androgen deprivation therapy (ADT) is the foundational treatment for metastatic prostate cancer (PCa). Androgen receptor (AR) axis-targeted therapies are a new standard of care for advanced PCa. Although these agents have significantly improved patient survival, the suppression of testosterone is associated with an increased risk of cardiometabolic syndrome. This highlights the urgency of multidisciplinary efforts to address the cardiometabolic risk of anticancer treatment in men with PCa.

Methods

Two professional organizations invited five urologists, five clinical oncologists, and two cardiologists to form a consensus panel. They reviewed the relevant literature obtained by searching PubMed for the publication period from April 2013 to April 2023, to address three discussion areas: (i) baseline assessment and screening for risk factors in PCa patients before the initiation of ADT and AR axis-targeted therapies; (ii) follow-up and management of cardiometabolic complications; and (iii) selection of ADT agents among high-risk patients. The panel convened four meetings to discuss and draft consensus statements using a modified Delphi method. Each drafted statement was anonymously voted on by every panelist.

Results

The panel reached a consensus on 18 statements based on recent evidence and expert insights.

Conclusion

These consensus statements serve as a practical recommendation for clinicians in Hong Kong, and possibly the Asia-Pacific region, in the management of cardiometabolic toxicities of ADT or AR axis-targeted therapies in men with PCa.

A Case Series of Bosworth Fracture-Dislocations and Review of 129 Reported Cases

Introduction

Bosworth fracture dislocations of the ankle are rare injuries of the ankle caused by extreme external rotation of the supinated foot where the proximal fibula fracture fragment is posteriorly dislocated and entrapped behind the posterior-lateral ridge of the tibia. This case series aims to document three such cases treated in our institution over a nine year period. We also provide a review of 129 cases in the existing literature.

Materials and methods

Medical records and relevant radiographs for each patient were analysed and collected from the time of presentation till the point of latest follow-up. During each clinic visit, all physical exam findings as well as all complications were recorded. The American Foot and Ankle Society (AOFAS) Hindfoot score was also tabulated for each patient at the point of latest review.

Results

Closed reduction was unsuccessful in all three patients, and all required open reduction. One patient had an uncomplicated recovery whilst the remaining two suffered significant soft tissue complications. One patient suffered severe soft tissue swelling preventing primary closure at the time of surgery, whilst another suffered post-operative wound dehiscence and infection. Eventually all fractures healed, and all three patients obtained satisfactory AOFAS scores.

Conclusion

The diagnosis of Bosworth fracture dislocations of the ankle is often delayed or missed, due to its rare occurrence. Closed reduction is often unsuccessful, and early open reduction is required to avoid poor clinical outcomes due to severe soft tissue damage or even compartment syndrome.

Identifying the spatiotemporal organization of high-traffic events in a mobile communication system using event synchronization and complex networks

In mobile communication systems, congestion is related to high-traffic events (HTEs) that occur in the coverage areas of base stations. Understanding, recognizing, and predicting these HTEs and researching their occurrence rules provides theoretical and decision-making support for preventing system congestion. Communication sectors are regarded as nodes, and if HTEs occur synchronously among sectors, then the corresponding nodes are connected. The total number of synchronous HTEs determines the edge weights. The mobile-communication spatiotemporal data are mapped to a weighted network, with the occurrence locations of HTEs as the basic elements. Network analysis provides a structure for representing the interaction of HTEs. By analyzing the topological features of the event synchronization network, the associations among the occurrence times of HTEs can be mined. We find that the event synchronization network is a small-world network, the cumulative strength distribution is exponential, and the edge weight obeys a power law. Moreover, the node clustering coefficient is negatively correlated with the node degree. A congestion coefficient based on several topological parameters is proposed, and the system congestion is visualized. The congestion coefficient contains information about the synchronous occurrence of HTEs between a sector and its neighbors and information about the synchronous occurrence of HTEs among its neighbors. For the mobile communication system considered in this study, the congestion coefficient of a large number of sectors is small and the risk of system congestion is low.

A new treatment paradigm for phlegmasia cerulea dolen: Single stage endovascular pharmacomechanical thrombectomy with venoplasty and stenting

BACKGROUND

Phlegmasia Cerulae Dolen (PCD) is potentially a lethal disease but there is currently no established treatment algorithm for it. The aim of this study was to assess the safety and effectiveness of single stage endovascular pharmacomechanical thrombectomy with venoplasty and stenting in the treatment of PCD.

METHOD

This was a retrospective single centre observational study of consecutive patients who underwent endovascular intervention for the treatment of PCD between June 2016 and March 2020. Clinical and procedural details were recorded. Procedural and clinical success rate, procedural complications, and 30 days mortality were reported.

RESULT

11 patients were treated during the study period. 2 (18.2%) had active malignancy. 63.6% were uncomplicated PCD on presentation. Common iliac vein compression or stenosis were demonstrated in all patients. Venous stents were implanted in all cases and procedures were successful in all cases. All patients had symptoms improvement at 72 hours post procedure. Other than 2 major bleeding complications, there was no other adverse event. The 30 days mortality was 18.2%. Active malignancy and the presence of anaemia were significantly associated with major complications.

CONCLUSION

Single stage endovascular thrombectomy and stenting was effective and safe in the treatment of patients with PCD. Common Iliac vein compression was a common underlying cause of PCD.

May-Thurner Syndrome Results in Life-Threatening Condition: Phlegmasia Cerulea Dolens and Rhabdomyolysis

Venography alone may underestimate the extent of common iliac vein compression in May-Thurner syndrome. Peripheral intravascular ultrasound is mandatory to better assess common iliac vein compression.

Urschel's Sign in Paget-Schroetter Syndrome: Multimodality Evaluation by Extravascular and Intravascular Imaging

Paget-Schroetter Syndrome is potentially life-threatening. In this case, multidisciplinary imaging with extravascular and intravascular evaluation guided the proper diagnosis and treatment planning.

Optical Coherence Tomography Evaluation of Superficial Femoral Artery Directional Atherectomy

To the best of our knowledge, this is the first report of optical coherence tomography evaluation of superficial femoral artery atherectomy in a patient from the Asia-Pacific region. We demonstrate the feasibility of this technique in Chinese populations.

Comprehensive identification of peptides in tandem mass spectra using an efficient open search engine

We present a sequence-tag-based search engine, Open-pFind, to identify peptides in an ultra-large search space that includes coeluting peptides, unexpected modifications and digestions. Our method detects peptides with higher precision and speed than seven other search engines. Open-pFind identified 70-85% of the tandem mass spectra in four large-scale datasets and 14,064 proteins, each supported by at least two protein-unique peptides, in a human proteome dataset.

Peripheral vascular manifestation in patients receiving an amphetamine analog: A case series

Amphetamine and its related derivatives and analogues (ADRA) are highly addictive central nervous system stimulants that are used commonly in the treatment of attention-deficit/hyperactivity disorder and narcolepsy. These medications are associated with many side effects but reports of peripheral arterial manifestations associated with ADRA usage are scarce. We retrospectively reviewed the records of 16 patients (median age 37 years (IQR 31–47), 13 females) referred to a single tertiary referral service while receiving ADRA. Follow-up was available for a median of 3 years (IQR 3–4.5). The most common presentation (62.5%) was mild vasospastic symptoms involving the upper, lower or both extremities. Six patients developed severe manifestations including tissue loss and the need for lower extremity amputation. Most patients (75%) refused to stop the medication during follow-up. Underlying rheumatologic disorders were found in 25% of the patients, and the presence of rheumatologic disease seemed to be associated with more severe vascular manifestations. In conclusion, it is important to search for ADRA usage as part of the differential diagnosis of digital ischemia.

What's Old is New Again - A Review of the Current Evidence of Colchicine in Cardiovascular Medicine

Colchicine is a well-established drug approved by the Food and Drug Administration (FDA) for the prevention and treatment of gout. It possesses unique anti-inflammatory properties. Interests in the usage of colchicine in cardiovascular medicine have been rekindled recently with several large trials been carried out to investigate its efficacy in treatment of various cardiac conditions including pericarditis, postpericardiotomy syndrome, atrial fibrillation and coronary artery disease. In this review, the basic pharmacological properties of colchicine will be discussed, and the evidences of its benefits for different applications in cardiovascular medicine will be reviewed.

Self-reported symptoms in patients on antiepileptic drugs in monotherapy

OBJECTIVE

To ascertain the frequency of self-reported symptoms in patients taking antiepileptic drugs (AED).

METHODS

We included patients on carbamazepine (CBZ) n = 36, valproate (VPA) n = 21, levetiracetam (LEV) n = 12, phenytoin (PHT) n = 11, lamotrigine (LTG) n = 20, patients not taking anticonvulsive drugs n = 19, and healthy control subjects (CTRL) n = 41 to complete the Liverpool Adverse Event Profile (LAEP).

RESULTS

The mean LAEP scores were CBZ/PHT/LEV/VPA/LTG/noAED/CTRL = 44.97/42.00/41.00/40.33/32.42/42.00/30.80. LEV scored overall in the same range as the older AED but had a different adverse effect profile with self-reported anger (33%) and shaky hands (42%) particularly frequent. Patients with depression or uncontrolled epilepsy had significantly higher LAEP scores than patients without depression or uncontrolled epilepsy.

CONCLUSION

Our unblinded observational study of self-reported symptoms suggested LTG was overall the drug with the least self-reported symptoms. Larger studies are needed to determine whether this was a truly significant difference. LEV had a different side effect profile to older AED. Confounding factors were depression and uncontrolled epilepsy. This observation should be further tested with randomized studies.

Distally pedicled peroneus brevis muscle flap: a versatile lower leg and foot flap

INTRODUCTION

The purpose of this study was to evaluate the outcome of our early experience with the distally pedicled peroneus brevis flap in the management of soft tissue defects of the lower leg, ankle and foot.

METHODS

This was a non-randomised, retrospective study involving five patients who were treated with the peroneus brevis muscle flap for soft tissue defects over the lower leg.

RESULTS

In all five patients, the flaps were viable and successful in providing satisfactory soft tissue coverage for the defects. In one diabetic patient, distal flap necrosis was observed, which was treated successfully with a local rotational skin flap.

CONCLUSION

The distally pedicled peroneus brevis muscle flap is an economical, reliable and relatively easy procedure for treating defects of the distal third of the leg, ankle and foot.

Role of warfarin pharmacogenetic testing in clinical practice

Chronic oral anticoagulation with warfarin is difficult to maintain within the therapeutic range and requires frequent monitoring and dose adjustments. Variations in two genes, VKORC1 and CYP2C9, have been associated with variation in warfarin metabolism among individuals. Patients with CYP2C9*2 and *3 variants have longer times to dose stabilization and are at higher risk of serious and life-threatening bleeding. VKORC1 polymorphisms significantly influence time to first therapeutic warfarin range, and variants in this gene determine low-, intermediate- and high-warfarin dose requirements. The prevalence of CYP2C9 and VKORC1 polymorphisms vary among different ethnic groups, and can account for over 30% of variance in warfarin dose. Recent studies suggest that the pharmacogenomics-guided dosing algorithm can accurately predict warfarin dosage and might reduce adverse events. We aim to review the pharmacogenetics of warfarin metabolism and the clinical role of genetic testing for warfarin therapy.

Surveillance programme for hepatocellular carcinoma improves the survival of patients with chronic viral hepatitis

BACKGROUND

The survival benefit of surveillance for hepatocellular carcinoma (HCC) is controversial.

AIM

We aimed to examine the survival benefit of HCC surveillance in chronic viral hepatitis.

METHODS

Survivals of HCC patients related to chronic viral hepatitis from the Hepatology Clinic (surveillance group) were compared with those referred from other hospitals/clinics (no-surveillance group). Lead-time and length-time biases were adjusted based on tumour volume doubling times.

RESULTS

Among 579 patients (91% hepatitis B), 472 (82%) patients had HCC and 79 (17%) of these patients were referred from the surveillance programme. HCC was smaller (4.2 vs. 7.7 cm; P<0.001) and fewer in numbers (2.6 vs. 3.8, P=0.03) in the surveillance group vs. the no-surveillance group. Treatment by surgery (20 vs. 10%, P=0.007) and local ablative therapy (46 vs. 19%, P<0.001) were more frequent in the surveillance group than that in the no-surveillance group. The median survival of the surveillance group (88 weeks) was significantly longer than that of the no-surveillance group (26 weeks) (P<0.001). The adjusted cumulative survival at 2 years was significantly longer in the surveillance group if the tumour volume doubling time was <90 days (P=0.0352).

CONCLUSIONS

HCC surveillance can improve the survival of patients with chronic viral hepatitis B.

In vitro effects of local anaesthetics on the thromboelastographic profile of parturients

BACKGROUND

Post-dural puncture headache can be an incapacitating complication of obstetric epidural analgesia/anaesthesia and early or prophylactic epidural blood patch (EBP) is one of the treatment options. Although local anaesthetic (LA) agents have been shown to have anticoagulation effects in vitro, peri-partum women are known to be hypercoagulable. We postulated that the presence of residual LA might not result in impaired haemostasis of the EBP in parturients.

METHODS

Blood samples from 10 healthy term parturients were subjected to thromboelastography after the addition of four different LA (lidocaine, bupivacaine, levobupivacaine, and ropivacaine) preparations.

RESULTS

There was a significant reduction in reaction (R) and coagulation (K) time (P<0.001, P<0.05) and an increase in alpha degrees angle (P<0.01) when comparing undiluted blood with the saline control group. Maximum amplitude (MA) and clot lysis (Ly30) did not change significantly despite the 50% dilution. The thromboelastographic parameters of all four LA-treated groups were no different from their saline controls and from each other.

CONCLUSION

At clinical dosages, LA did not cause any hypocoagulable changes on the thromboelastographic profile of healthy parturients.

Bronchial diameters in children--use of the Fogarty catheter for lung isolation in children

The right and left main bronchial diameters of 250 children were measured using computed tomography of the thorax. In 75% of the cases, the right main bronchial diameter was significantly larger than the left (95% CI 0.7-0.9, P<0.01). Age but not weight of a child is a good predictor of the bronchial diameter (Beta value is 2.81x10(-2) and 2.58x10(-2) for right and left main bronchial diameter respectively). A size 3 Fogarty catheter will provide effective bronchial blocking for children up to 4 years old. A size 5 Fogarty catheter can be used for most children from 5 to 12 years old. Larger Fogarty catheters or double-lumen tubes can be used in older children. Overinflation of the cuff should be avoided by fibreoptic bronchoscopy of the balloon. Our clinical application of the technique is discussed.

Teaching first-year medical students physiology: does the human patient simulator allow for more effective teaching?

BACKGROUND

Although the Human Patient Simulator (HPS) is an effective teaching tool in many medical fields, literature supporting its use in the teaching of physiology to medical students is lacking. This study investigated the effectiveness of HPS-based teaching of cardiovascular physiology to first-year medical students.

METHODS

Two hundred and ten first-year medical students were scheduled to our HPS laboratory with the purpose of demonstrating "physiology in action". Students were divided into groups of 19-25 each, and attended a lecture followed by a HPS session. Using a theatre-type simulator complete with mannequin, anaesthesia machine and monitors (METI, Sarasota FL), the scenarios of hypovolaemia, sepsis, and cardiac failure were run to demonstrate the physiological changes that occur with changes in preload, afterload, and cardiac contractility. Each student was given a true/false test before, and again after the HPS session, followed by a survey of their learning experience.

RESULTS

There was marked improvement in test scores after the HPS session (82.1% vs. 64.6%, P < 0.001). Most of the students felt that HPS was a better teaching tool (94.5%) and raised more questions (76.5%) than lectures. They wanted more topics to be taught this way (96%), as they could apply and re-enforce textbook knowledge, and visualise real-time changes. However, they felt that their experience could have been enhanced with more time and smaller groups.

DISCUSSION

HPS is an excellent teaching tool as it stimulates student curiosity and makes knowledge acquisition and understanding easier. It is highly desirable to be incorporated into the teaching of physiology.

Critical incidents in paediatric anaesthesia: an audit of 10 000 anaesthetics in Singapore

BACKGROUND

We undertook an audit of paediatric perioperative incidents in the first 10000 anaesthetics administered in KK Women's and Children's Hospital in Singapore between May 1997 and April 1999. The spectrum of surgery performed ranged from simple ambulatory surgery to open heart surgery for complicated congenital heart diseases.

METHODS

An audit form is completed for every anaesthetic delivered and critical incidents are reported on the reverse blank page of the audit form. An anaesthetic incident was defined as 'any incident which affected, or could have affected, the safety of the patient under anaesthetic care'.

RESULTS

Two hundred and ninety-seven critical incidents were reported. The majority of them happened in healthy patients (80.1% ASA I and II) scheduled for elective surgery (73.3%). Critical incidents in infants less than 1 year of age were four times as common as in older children (8.6% versus 2.1%). Incidents occurred mainly during maintenance (80.6%). There was no anaesthetic mortality. Respiratory events were the most common (77.4%) with laryngospasm accounting for 35.7%. Cardiovascular incidents (10.8%) included hypotension from haemorrhage and sepsis, and dysrhythmias. The incidence of equipment and pharmacologically related problems was low.

CONCLUSIONS

Future reviews of a larger patient population may be helpful to determine trends of perioperative events and whether quality assurance programs have made a difference.

Experience with video-assisted thoracoscopic surgery in the management of complicated pneumonia in children

PURPOSE

The aim of this study was to assess the impact of video assisted thoracoscopic surgery (VATS) in the management of empyema in children.

METHODS

This report involves cases of complicated pneumonia in children requiring surgical intervention after failure of medical treatment with antibiotics, with or without drainage from November 1997 to October 1999. The impact of VATS has been studied prospectively from October 1998 when VATS was introduced. The results have been compared with the previous year when similar cases were dealt with open thoracotomy. These 2 groups of patients with VATS (V) or without VATS (O) were studied for their progress in hospital and the final outcome.

RESULTS

A total of 39 immunocompetent children with community-acquired pneumonia were studied. There were 17 cases in O and 22 in V. There were 2 conversions to open thoracotomy in V. Both of these cases required resection of the lung parenchyma for severe necrosis and bronchopleural fistula. The mean age in years was 5.3 (O) and 4.9 (V). Parameters that were significantly less in V compared with O include timing of referral (O, 13.6 days; V, 5.3 days), number of lung resections (O, 8; V, 2), blood transfusion (O, 14; V, 2), analgesia requirements (O, 7.8 days; V, 2.9 days), postoperative length of stay in hospital (O, 10.4 days; V, 4.6 days), time to become normothermic (O, 5.6 days; V, 1.7 days); and time to removal of chest drains (O, 6.0 days; V, 2.7 days). Cosmesis is superior in cases of VATS compared with open thoracotomy. All the children recovered well on follow-up with resolution of symptoms and no recurrences.

CONCLUSIONS

(1) VATS has ushered in a new era of hope for patients with complicated pneumonia. (2) Thoracotomy, lung resections, and the attending morbidity rate have decreased. (3) Patients are being referred earlier by the physicians because the management protocol is changing.

Anaesthesia for tracheoplasty: case report and review of anaesthesia techniques

Congenital tracheal stenosis is an uncommon cause of stridor and can be associated with other anomalies. It may present anytime during childhood depending on the severity of the lesion. The anaesthetist may be involved in all stages of management of this problem; from diagnostic investigations to surgical correction. Various methods of tracheoplasty have been described, some requiring cardiopulmonary bypass support and others may be carried out with conventional ventilatory techniques.