A History and Modern Framework for Quality Improvement in Interventional Radiology

Quality improvement (QI) initiatives have benefited patients as well as the broader practice of medicine. Large-scale QI has been facilitated by multi-institutional data registries, many of which were formed out of national or international medical society initiatives. With broad participation, QI registries have provided benefits that include but are not limited to establishing treatment guidelines, facilitating research related to uncommon procedures and conditions, and demonstrating the fiscal and clinical value of procedures for both medical providers and health systems. Because of the benefits offered by these databases, Society of Interventional Radiology (SIR) and SIR Foundation have committed to the development of an interventional radiology (IR) clinical data registry known as VIRTEX. A large IR database with participation from a multitude of practice environments has the potential to have a significant positive impact on the specialty through data-driven advances in patient safety and outcomes, clinical research, and reimbursement. This article reviews the current landscape of societal QI programs, presents a vision for a large-scale IR clinical data registry supported by SIR, and discusses the anticipated results that such a framework can produce.

Hepatocellular carcinoma locoregional therapies: Outcomes and future horizons

Hepatocellular carcinoma (HCC) is the most common primary cancer of the liver and has an overall five-year survival rate of less than twenty percent. For patients with unresectable disease, evolving liver-directed locoregional therapies provide efficacious treatment across the spectrum of disease stages and via a variety of catheter-directed and percutaneous techniques. Goals of locoregional therapies in HCC may include curative intent in early-stage disease, bridging or downstaging to surgical resection or transplantation for early or intermediate-stage disease, and local disease control and palliation in advanced-stage disease. This review explores the outcomes of chemoembolization, bland embolization, radioembolization, and percutaneous ablative therapies. Attention is also given to prognostic factors related to each of the respective techniques, as well as future directions of locoregional therapies for HCC.

Computational evaluation of inferior vena cava filters through computational fluid dynamics methods

Numerical simulation is growing in its importance toward the design, testing and evaluation of medical devices. Computational fluid dynamics and finite element analysis allow improved calculation of stress, heat transfer, and flow to better understand the medical device environment. Current research focuses not only on improving medical devices, but also on improving the computational tools themselves. As methods and computer technology allow for faster simulation times, iterations and trials can be performed faster to collect more data. Given the adverse events associated with long-term inferior vena cava (IVC) filter placement, IVC filter design and device evaluation are of paramount importance. This work reviews computational methods used to develop, test, and improve IVC filters to ultimately serve the needs of the patient.

Characterization of the #Radiology Twitter Conversation During the Global COVID-19 Pandemic

OBJECTIVE

To assess the #Radiology conversation on Twitter social media platform during the COVID-19 pandemic.

MATERIALS AND METHODS

From February 1 to December 31, 2020, all tweets with a #Radiology hashtag were identified using the healthcare social media analytics tool, Symplur Signals. Data collected included number of tweets, retweets, impressions, links, and user characteristics. Data were stratified by the presence of a COVID-19-related keyword, and a social media network analysis was further performed.

RESULTS

Of the 68,172 tweets, 10,093 contained COVID-19 content from 2809 users generating 65,513,669 impressions. More tweets with COVID-19 content contained links than without (P < 0.01). Network analysis demonstrated most users were physicians (48.10%), authoring the most tweets (40.38%), using the most mentions (32.15%), and retweeting the most (51.45%). The most impressions, however, were by healthcare organizations not providing clinical care (20,235,547 impressions, 30.89%). Users came from 80 countries, most from the United States (29.3%) and the United Kingdom (8.69%). During early March, COVID-19 dominated the #Radiology conversation, making up 54.67% of tweets the week of March 14 and 64.74% of impressions the week of March 21 compared to 13.97% of tweets and 16.76% of impressions in the remainder of the study period (P < 0.01).There was an influx of new users to the #Radiology conversation during this time period with more users tweeting about COVID-19 than not (P < 0.01).

CONCLUSION

Discussion of COVID-19 in the #Radiology community increased significantly during the early weeks of the pandemic. Real time sharing and collaboration proved a useful tool when rapid information dissemination was needed to manage an emerging pathogen.

Noninvasive Approaches for Anxiety Reduction During Interventional Radiology Procedures

Periprocedural anxiety is a major cause of morbidity, particularly for interventional radiology procedures that often depend on conscious sedation. Management of anxiety and pain during image-guided procedures has traditionally relied on pharmacologic agents such as benzodiazepines and opioids. Although generally safe, use of these medications risks adverse events, and newer noninvasive, nonpharmacologic techniques have evolved to address patient needs. In this review, we explore the roles of hypnosis, structured empathic attention, anodyne imagery, music, video glasses, and mobile applications in reducing procedural anxiety and pain with the goal of improving patient satisfaction, operational efficiency, and clinical outcomes.

Intravascular Ultrasound for the Peripheral Vasculature-Current Applications and New Horizons

Intravascular ultrasound (IVUS) is a proven and rapidly developing imaging modality that can be used for a multitude of both diagnostic and interventional purposes. By allowing for superior intraluminal characterization, compared with angiography, IVUS has emerged as a technically valuable tool in interventional procedures such as transjugular intrahepatic portosystemic shunt/direct intrahepatic portosystemic shunt, venous interventions (May Thurner stenting, inferior vena cava filter placement, recanalization in the setting of chronic venous thrombosis/insufficiency), percutaneous fenestration in the setting of aortic dissection and angioplasty. Additional applications evaluating coronary arteries and plaque morphology have been described, but are outside the scope of this review. In addition to IVUS's merit as a pre- and intra-procedural guidance modality, there are also several advantages compared to the gold standard of angiography which include decreased need for iodinated contrast, decreased radiation exposure and decreased procedural times in certain cases. With current research, such as that aimed at supraharmonic imaging, further improvements in imaging depth, resolution and contrast to noise ratio are on the horizon.

Advanced stage breast cancer is associated with catheter-tip thrombus formation following implantable central venous port placement

PURPOSE

Catheter-tip associated thrombosis is not uncommon in patients with implantable central venous ports; however, the prevalence and clinical impact of this complication on patient management is unclear. This study aims to identify risk factors for thrombus formation in a large population receiving serial echocardiograms (echo) following port placement.

METHODS

A total of 396 female breast cancer patients underwent internal jugular vein chest port placement between 2007 and 2013 and received echo studies every third month. Catheter tip position was measured from chest radiography and catheter associated thrombus was identified by echo.

RESULTS

Sixteen out of 396 patients (4%) had catheter-tip thrombus. No patients were symptomatic or prophylactically anticoagulated. Patients with thrombus were significantly younger than those without (46.4 years versus 53.4 years, respectively, p = 0.02) and had higher stage breast cancer with 75% versus 44.7% having stage III or IV cancer ( p = 0.017). Thrombus was identified after a median of 91 days. No significant difference was identified in anatomic ( p = 0.1) or measured ( p = 0.15) tip position, port laterality ( p = 0.86), or number of port lumens ( p = 0.65).

CONCLUSIONS

In this large cohort, younger patients and those with more advanced stage breast cancer were more associated with catheter-tip-related thrombus after port placement.

Yttrium-90 microsphere selective internal radiation therapy for liver metastases following systemic chemotherapy and surgical resection for metastatic adrenocortical carcinoma

Adrenocortical carcinoma (ACC) is a rare malignancy with generally poor outcomes and limited treatment options. While surgical resection can be curative for early local disease, most patients present with advanced ACC owing to nonspecific symptoms. For those patients, treatment options include systemic chemotherapy and locoregional therapies including radiofrequency ablation and transarterial chemoembolization. We present the first reported case of utilizing yttrium-90 microsphere selective internal radiation therapy (SIRT) in combination with first line EDP-M (Etoposide, Doxorubicin, Cisplatin, Mitotane) chemotherapy and debulking surgical primary tumor resection for treatment of metastatic ACC. Stable complete radiologic response has been maintained after twelve months with resolution of clinical symptoms. These findings prompt the need for further consideration and studies to elucidate the role of SIRT in combination with systemic and surgical treatment for metastatic ACC.

Retrieval characteristics of the Bard Denali and Argon Option inferior vena cava filters

OBJECTIVE

The purpose of this study was to compare the retrieval characteristics of the Option Elite (Argon Medical, Plano, Tex) and Denali (Bard, Tempe, Ariz) retrievable inferior vena cava filters (IVCFs), two filters that share a similar conical design.

METHODS

A single-center, retrospective study reviewed all Option and Denali IVCF removals during a 36-month period. Attempted retrievals were classified as advanced if the routine "snare and sheath" technique was initially unsuccessful despite multiple attempts or an alternative endovascular maneuver or access site was used. Patient and filter characteristics were documented.

RESULTS

In our study, 63 Option and 45 Denali IVCFs were retrieved, with an average dwell time of 128.73 and 99.3 days, respectively. Significantly higher median fluoroscopy times were experienced in retrieving the Option filter compared with the Denali filter (12.18 vs 6.85 minutes; P = .046). Use of adjunctive techniques was also higher in comparing the Option filter with the Denali filter (19.0% vs 8.7%; P = .079). No significant difference was noted between these groups in regard to gender, age, or history of malignant disease.

CONCLUSIONS

Option IVCF retrieval procedures required significantly longer retrieval fluoroscopy time compared with Denali IVCFs. Although procedure time was not analyzed in this study, as a surrogate, the increased fluoroscopy time may also have an impact on procedural direct costs and throughput.

Cost-benefit analysis of establishing an inferior vena cava filter clinic

PURPOSE

Adverse events associated with retrievable inferior vena cava filters (IVCFs) have generated an increased interest in improving IVCF retrieval rates to improve patient safety and quality care. This study aims to demonstrate the cost-benefit of implementing an IVCF clinic to improve patient care in an institution in the United States.

METHODS

An IVCF clinic was established at a single institution in September 2012 and for ten months referring physicians were contacted to facilitate retrieval when appropriate. Additionally, a retrospective review was conducted on filter placements over the eight preclinic months. Cost-benefit analysis was conducted by creating a model, which incorporated the average cost and reimbursement for permanent and retrievable IVCFs.

RESULTS

A total of 190 IVCFs (152 retrievable IVCFs and 38 permanent IVCFs) were implanted during the IVCF clinic period. Twenty-nine percent of the retrievable IVCFs were successfully retrieved compared to 10 of 119 retrievable IVCFs placed during the preclinic period (8.4%). Cost-benefit analysis, using the average of the institution's six most common reimbursement schedules, demonstrated an average net financial loss per permanent or retrievable IVCF not removed. However, a net financial gain was realized for each retrievable IVCF removed. The additional hospital cost to maintain the IVCF clinic was offset by removing an additional 3.1 IVCFs per year.

CONCLUSION

An IVCF clinic significantly increases retrieval rates, promotes patient safety, and is economically feasible. Given the adverse event profile of retrievable IVCFs, strategic efforts such as these ultimately can improve quality care for patients with in-dwelling IVCFs.

Role of inferior vena cava filters in transplant patients

PURPOSE

This study evaluates the selection, use, and risks of permanent and retrievable inferior vena cava filters (IVCFs) in patients who have undergone organ transplantation.

MATERIALS AND METHODS

Single-center retrospective review of 35 patients who had an IVCF placed following organ transplantation. Patient demographics, IVCF indication, and eligibility for retrieval were reviewed. Computed tomography (CT) studies showing the filter (n=22) were evaluated independently for IVCF adverse effects.

RESULTS

Thirty-two (91%) of 35 patients had retrievable IVCFs placed while three (9%) patients received permanent IVCFs. Filter retrieval was indicated in three of the 32 patients receiving retrievable filters and was performed in two cases. Patients were ineligible for retrieval due to short life expectancy, complications/contraindications to anticoagulation, extended filter dwell time, lost to follow-up, and undetermined therapeutic value of anticoagulation.

CONCLUSION

Current practices of filter placement usually dictate placing a retrievable IVCF in transplant patients. However, transplant patients are unlikely to be eligible for filter retrieval especially in situations of advanced age and comorbidities. Given the low incidence of eligibility for retrieval in this patient population, these results suggest preferential placement of permanent filters may reduce the potential morbidity due to filter-related complications, such as strut perforation, in transplant patients.

Conventional versus Drug-Eluting Bead Transarterial Chemoembolization for Neuroendocrine Tumor Liver Metastases

PURPOSE

To compare outcomes of conventional transarterial chemoembolization with drug-eluting bead (DEB) chemoembolization for treatment of neuroendocrine tumor liver metastases.

MATERIALS AND METHODS

This single-center, retrospective study evaluated 177 transarterial chemoembolization treatments (78 conventional chemoembolization treatments using ethiodized oil-based cisplatin, mitomycin C, and doxorubicin and 99 DEB chemoembolization treatments using doxorubicin-loaded 100-300 μm DEBs) from 2012 to 2015. Hepatic disease distribution was 93% bilobar for both groups with largest lesion size 5.0 cm ± 2.7. No difference was noted in regard to lesion size or distribution, carcinoid syndrome, or pancreastatin production. Clinical outcomes including complications; liver function tests (LFTs); and radiologic (modified Response Evaluation Criteria in Solid Tumors), biochemical (pancreastatin levels), and symptomatic responses were evaluated at 1-month follow-up.

RESULTS

Higher symptomatic response (complete and partial) was identified with conventional transarterial chemoembolization compared with DEB chemoembolization (47% vs 30%; P < .05). Patients receiving DEB transarterial chemoembolization experienced lower elevation of LFTs (aspartate aminotransferase, 39 U/L vs 122 U/L; alanine aminotransferase, 20 U/L vs 93 U/L; bilirubin, 0.001 mg/dL vs 0.123 mg/dL; P < .05) and less postembolization syndrome (50% vs 67%; P < .05). Patients undergoing first-time DEB transarterial chemoembolization had lower periprocedural octreotide maximum rate requirements (58 μg/h vs 66 μg/h; P < .05). No difference was observed in biochemical (P = .60) or radiologic (P < .20) responses.

CONCLUSIONS

Conventional transarterial chemoembolization yields better symptomatic response and may be preferred for patients experiencing carcinoid symptoms. DEB transarterial chemoembolization, with lower LFT elevations and postembolization syndrome incidence, may be preferred for patients with poor liver function.

Etiology and treatment of acute inferior vena cava thrombosis

Inferior vena cava thrombosis (IVCT) is a rare but severe disease that is associated with a high rate of mortality. IVCT can be categorized into primary versus secondary thrombosis dependent upon the underlying pathophysiology. The diagnosis includes both clinical probability assessment as well as the imaging evaluation. The optimal therapeutic strategy remains the target of continued research. Although anticoagulation therapy remains fundamental in treating IVCT, its inherent limitations have led to the use of minimally invasive, endovascular treatment options, including transcatheter thrombolysis, mechanical thrombectomy or a combination of these techniques. This review focuses on the etiology, diagnostic assessment, and endovascular treatment options for IVCT.

Elevated Alkaline Phosphatase Prior to Transarterial Chemoembolization for Neuroendocrine Tumors Predicts Worse Outcomes

INTRODUCTION

We hypothesized that an elevated preoperative alkaline phosphatase (AP) predicted worse outcomes for patients undergoing transarterial chemoembolization (TACE) for neuroendocrine tumor (NET) liver metastases.

METHODS

We reviewed all patients who underwent TACE for metastatic NET between 2009 and 2013. Survival was evaluated using preprocedure variables.

RESULTS

One hundred and nine patients underwent 210 TACE procedures. The average age was 57.7 years (range 20-78). Primary sites included pancreas (N = 20), other gastrointestinal (N = 52), lung (N = 9), and unknown (N = 28). The tumor was grade 1 in 68 (62 %), grade 2 in 21 (19 %), and grade 3 in 3 (3 %). Extrahepatic disease was present in 54 (50 %) and greater than 50 % hepatic tumor burden by imaging in 63 (58 %). Elevated bilirubin occurred in 8 (7 %), elevated AP in 22 (20 %), elevated ALT in 21 (19 %), and elevated AST in 41 (38 %). Univariate predictors included tumor grade (43 vs 27 vs 21 months, p = 0.015), hepatic tumor burden (59 vs 37 months, p = 0.009), and elevated AP (59 vs 23 months, p < 0.001). On multivariate analysis, only elevated AP (p = 0.001) predicted worse survival.

CONCLUSIONS

Elevated AP prior to TACE for metastatic NET portends a worse survival outcome, even more so than tumor grade or extent of hepatic disease.

A Systematic Review of Acquired Uterine Arteriovenous Malformations: Pathophysiology, Diagnosis, and Transcatheter Treatment

Objective An acquired uterine arteriovenous malformation (AVM) is a rare cause of vaginal bleeding and, although hysterectomy is the definitive therapy, transcatheter embolization (TCE) provides an alternative treatment option. This systematic review presents the indications, technique, and outcomes for transcatheter treatment of the acquired uterine AVMs. Study Design Literature databases were searched from 2003 to 2013 for eligible clinical studies, including the patient characteristics, procedural indication, results, complications, as well as descriptions on laterality and embolic agents utilized. Results A total of 40 studies were included comprising of 54 patients (average age of 33.4 years). TCE had a primary success rate with symptomatic control of 61% (31 patients) and secondary success rate of 91% after repeated embolization. When combined with medical therapy, symptom resolution was noted in 48 (85%) patients without more invasive surgical procedures. Conclusion Low-level evidence supports the role of TCE, including in the event of persistent bleeding following initial embolization, for the treatment of acquired uterine AVMs. The variety of embolic agents and laterality of approach delineate the importance of refining procedural protocols in the treatment of the acquired uterine AVM. Condensation A review on the management of patients with acquired uterine AVMs.

Ureteroarterial fistula following retrograde ureteral stenting in a patient with a double-barreled wet colostomy for cervical cancer

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Ureteroarterial fistula (UAF) is a rare cause of massive hematuria.

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Percutaneous retrograde ureteral stents via DBWC can be done safely in the compliant patient for improved comfort.

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Understanding the anatomy, risks, and minimally invasive treatment options for UAF is important for prompt patient care.

AIDS Presenting as Granulomatous Amebic Encephalitis: PET and MR Imaging correlation

Granulomatous amebic encephalitis (GAE) is a rare and oftentimes fatal disease in immune compromised patients caused by free living amebae Acanthamoeba and Balamuthia. We report a patient in whom GAE secondary to Acanthamoeba was the initial presentation of acquired immunodeficiency syndrome in a 41-year-old male, and discuss the FDG positron emission tomography (PET) and magnetic resonance imaging findings that preceded the pathological diagnosis. The PET results provided complementary information when coupled with the MR brain findings. Improved understanding of the clinical and imaging findings of this deadly disease is the best hope for early diagnosis and treatment of this uncommon but deadly disease.

Surgical and endovascular treatment of hepatic arterial complications following liver transplant

Vascular complications after liver transplantation increase post-operative morbidity and contribute to the incidence of retransplantation. Vascular complications comprise arterial, caval, and portal venous pathology, with the majority of complications being arterial in etiology, including anastomotic stricture, pseudoaneurysm, and thrombosis. There are two major therapeutic options for the treatment of these arterial complications: endovascular intervention and surgery. The former includes intra-arterial thrombolysis, embolization, percutaneous transluminal angioplasty, and stent placement. The latter includes thrombectomy, reanastomosis, and retransplantation. Although surgical treatment has been considered the first choice for management in the past, advances in endovascular intervention have increased and make it a viable therapeutic option following orthotopic liver transplantation. This review focuses on the role of surgical and endovascular therapy in the management of hepatic arterial complications after liver transplantation.

Ultrasound-accelerated, catheter-directed thrombolysis for inferior vena cava thrombosis after an orthotopic liver transplant

Inferior vena cava thrombosis is a rare occurrence after an orthotopic liver transplant that is associated with a high rate of retransplant and mortality. There is no consensus regarding the optimal therapeutic strategy. Surgical management, including thrombectomy with revision of the cavocaval anastomosis, has been described. With the use of endovascular therapies, several minimally invasive approaches are available that are effective and avoid the high morbidity associated with reoperative surgery. We describe our successful experience using an approach after a liver transplant in which the inferior vena cava thrombosis in a patient presenting with acute renal failure, anorexia, weight loss, and fatigue using an ultrasound-accelerated, catheter-directed thrombolysis platform in conjunction with systemic anticoagulation.

Measurement of the ZZ production cross section and limits on anomalous neutral triple gauge couplings in proton-proton collisions at sqrt[s] = 7 TeV with the ATLAS detector

A measurement of the ZZ production cross section in proton-proton collisions at sqrt[s] = 7 TeV using data corresponding to an integrated luminosity of 1.02 fb(-1) recorded by the ATLAS experiment at the LHC is presented. Twelve events containing two Z boson candidates decaying to electrons and/or muons are observed, with an expected background of 0.3 ± 0.3(stat)(-0.3)(+0.4)(syst) events. The cross section measured in a phase-space region with good detector acceptance and for dilepton masses within the range 66 to 116 GeV is σ(ZZ → ℓ+ ℓ- ℓ+ ℓ-)(fid) = 19.4(-5.2)(+6.3)(stat)(-0.7)(+0.9)(syst) ± 0.7(lumi) fb. The resulting total cross section for on-shell ZZ production, σ(ZZ)(tot) = 8.5(-2.3)(+2.7)(stat)(-0.3)(+0.4)(syst) ± 0.3(lumi) pb, is consistent with the standard model expectation of 6.5(-0.2)(+0.3) pb calculated at the next-to-leading order in QCD. Limits on anomalous neutral triple gauge boson couplings are derived.

Expression of a mutant p193/CUL7 molecule confers resistance to MG132- and etoposide-induced apoptosis independent of p53 or Parc binding

p193/CUL7 is an E3 ubiquitin ligase initially identified as an SV40 Large T Antigen binding protein. Expression of a dominant interfering variant of mouse p193/CUL7 (designated 1152stop) conferred resistance to MG132- and etoposide-induced apoptosis in U2OS cells. Immune precipitation/Western analyses revealed that endogenous p193/CUL7 formed a complex with Parc (a recently identified parkin-like ubiquitin ligase) and p53. Apoptosis resistance did not result from 1152stop-mediated disruption of the endogenous p193/CUL7 binding partners. Moreover, 1152stop molecule did not directly bind to endogenous p193/CUL7, Parc or p53. These data suggested a role for p193/CUL7 in the regulation of apoptosis independently of p53 and Parc activity.

Stem cell therapy for ischemic heart disease

Recent experimental and clinical observations have suggested that cell transplantation could be of therapeutic value for the treatment of heart disease. This approach was based on the idea that transplanted donor cardiomyocytes would integrate with the host myocardium and thereby directly contribute to cardiac function. Surprisingly, the observation that non-cardiomyogenic cells could also improve cardiac function indicates that functional integration of donor cells might not be required to achieve a beneficial effect. More recently, several observations have suggested the presence of a greater than anticipated developmental repertoire in adult-derived stem cells, which, if further validated, would offer unprecedented opportunities for the restoration of cardiac function in diseased hearts. Here, we discuss current issues regarding the potential use of stem cell transplantation for the treatment of ischemic heart disease.

Haematopoietic stem cells do not transdifferentiate into cardiac myocytes in myocardial infarcts

The mammalian heart has a very limited regenerative capacity and, hence, heals by scar formation. Recent reports suggest that haematopoietic stem cells can transdifferentiate into unexpected phenotypes such as skeletal muscle, hepatocytes, epithelial cells, neurons, endothelial cells and cardiomyocytes, in response to tissue injury or placement in a new environment. Furthermore, transplanted human hearts contain myocytes derived from extra-cardiac progenitor cells, which may have originated from bone marrow. Although most studies suggest that transdifferentiation is extremely rare under physiological conditions, extensive regeneration of myocardial infarcts was reported recently after direct stem cell injection, prompting several clinical trials. Here, we used both cardiomyocyte-restricted and ubiquitously expressed reporter transgenes to track the fate of haematopoietic stem cells after 145 transplants into normal and injured adult mouse hearts. No transdifferentiation into cardiomyocytes was detectable when using these genetic techniques to follow cell fate, and stem-cell-engrafted hearts showed no overt increase in cardiomyocytes compared to sham-engrafted hearts. These results indicate that haematopoietic stem cells do not readily acquire a cardiac phenotype, and raise a cautionary note for clinical studies of infarct repair.

Cell cycle regulation to repair the infarcted myocardium

Lower vertebrates such as newt and zebrafish are able to reactivate high levels of cardiomyocyte cell cycle activity in response to experimental injury resulting in apparent regeneration. In contrast, damaged myocardium is replaced by fibrotic scar tissue in higher vertebrates. This process compromises the contractile function of the surviving myocardium, ultimately leading to heart failure. Various strategies are being pursued to augment myocyte number in the diseased hearts. One approach entails the reactivation of cell cycle in surviving cardiomyocytes. Here, we provide a summary of methods to monitor cell cycle activity, and interventions demonstrating positive cell cycle effects in cardiomyocytes as well as discuss the potential utility of cell cycle regulation to augment myocyte number in diseased hearts.

Myocyte and myogenic stem cell transplantation in the heart

Cellular transplantation is emerging as a potential mechanism with which to augment myocyte number in diseased hearts. To date a number of cell types have been shown to successfully engraft into the myocardium, including fetal, neonatal, and embryonic stem cell-derived cardiomyocytes, skeletal myoblasts, and stem cells with apparent cardiomyogenic potential. Here we provide a review of studies wherein myocytes or stem cells with myogenic potential have been transplanted into the heart. In addition, issues pertaining to the tracking and functional consequences of cell transplantation are discussed.

Rate-dependent [K+](o) accumulation in canine right atria in vivo: electrophysiological consequences

Sudden increases in heart rate cause accumulation of K+ in the extracellular space. However, the exact relationship between rate and extracellular K+ concentration ([K+](o)) in vivo is unknown. We measured [K+](o) in right atria of anesthetized dogs by using K(+)-sensitive electrodes. Peak increase in [K+](o) ranged from 0.18 +/- 0.04 mM [means +/- SE; cycle length (CL) = 350 ms] to 0.80 +/- 0.09 mM (CL = 250 ms) above baseline (3.50 +/- 0.08 mM at CL = 380 ms; n = 5). During rapid pacing-induced atrial fibrillation, peak increase in [K+](o) averaged 0.80 +/- 0.07 mM (n = 5). Whole cell current-clamp measurements in single right atrial myocytes (n = 5) showed that raising [K+](o) from 3 to 5 mM in 1-mM steps progressively depolarized resting membrane potential and reduced both phase 0 action potential amplitude and maximal upstroke velocity. Multisite epicardial mapping (n = 4) demonstrated that sudden rate increases changed longitudinal conduction velocity (CV(L)) by -3.6 +/- 1.8% to -5.9 +/- 1.2% over a CL range of 330 to 250 ms. Our observations suggest that rate-related [K+](o) accumulation in vivo is of sufficient magnitude to modulate those cellular electrophysiological properties that determine atrial CV(L).