Arrhythmias after heart transplantation: mechanisms and management

Keeping It "Current": A Review of Treatment Options for the Management of Supraventricular Tachycardia

OBJECTIVE

To review treatment options and updates that exist for the management of paroxysmal supraventricular tachycardia (PSVT).

DATA SOURCES

A literature search of PubMed was performed including articles from 1974 to June 2023 using the terms: arrhythmias, adenosine, verapamil, diltiazem, esmolol, propranolol, metoprolol, beta-blockers, amiodarone, PSVT, synchronized cardioversion, methylxanthines, dipyridamole, pediatrics, heart transplant, and pregnancy. Primary literature and guidelines were reviewed.

STUDY SELECTION AND DATA EXTRACTION

Studies were considered if they were available in English and conducted in humans.

DATA SYNTHESIS

PSVT is a subset of supraventricular tachycardia (SVT) that presents as a rapid, regular tachycardia with an abrupt onset and termination. Due to frequent emergency department (ED) visits annually with symptoms of PSVT, appropriate and efficient management of these patients is vital. This review provides an overview of the pathophysiology of PSVT, while also describing the literature behind nonpharmacologic and pharmacologic management of PSVT.

RELEVANCE TO PATIENT CARE AND CLINICAL PRACTICE

This review describes new literature regarding the improved success of the modified Valsalva maneuver as a nonpharmacologic therapy in PSVT. In addition, it describes a new technique in administration of adenosine that has improved outcomes, defines dose adjustments needed for drug interactions with adenosine, compares the utilization of nondihydropyridine calcium channel blockers with adenosine, and provides management recommendations for patients in special populations.

CONCLUSIONS

With high annual rates of ED visits for SVT, providers should be aware of the data behind management and modifications of therapy based on patient-specific factors (ie, patient preference, pharmacokinetics/pharmacodynamics, drug interactions, and special populations).

Posttransplant atrial fibrillation: Evidence of early posttransplant recipient-to-donor atrioatrial connections

INTRODUCTION

Atrial fibrillation and atrial flutter originating from the donor s heart is a commonly reported complication post heart transplant. Atrial tachyarrhythmia originating from the recipient s heart, propagated through recipient-to-donor connections, is rare with only few cases reported in the literature; most reported cases from our review occur years post-transplant.

CASE

A 47-year-old male presented with atrial tachycardia 6 months post heart transplant. Electrophysiologic study demonstrated atrial fibrillation originating from native heart and propagated through atrio-atrial connections to the donor heart. This arrhythmia was successfully terminated with radiofrequency ablation.

CONCLUSION

Atrio-atrial connection between recipient and donor can form as early as a few months post heart transplant. Radiofrequency ablation appears to be an effective treatment for atrial fibrillation propagated through donor-to-recipient connections.

Heart transplantation and biomarkers: a review about their usefulness in clinical practice

Advanced heart failure (AdvHF) can only be treated definitively by heart transplantation (HTx), yet problems such right ventricle dysfunction (RVD), rejection, cardiac allograft vasculopathy (CAV), and primary graft dysfunction (PGD) are linked to a poor prognosis. As a result, numerous biomarkers have been investigated in an effort to identify and prevent certain diseases sooner. We looked at both established biomarkers, such as NT-proBNP, hs-troponins, and pro-inflammatory cytokines, and newer ones, such as extracellular vesicles (EVs), donor specific antibodies (DSA), gene expression profile (GEP), donor-derived cell free DNA (dd-cfDNA), microRNA (miRNA), and soluble suppression of tumorigenicity 2 (sST2). These biomarkers are typically linked to complications from HTX. We also highlight the relationships between each biomarker and one or more problems, as well as their applicability in routine clinical practice.

Methylxanthine Derivatives in the Treatment of Sinus Node Dysfunction: A Systematic Review

While the chronotropic effects of theophylline and aminophylline are well-known, their clinical application in the treatment of sinus node dysfunction has not been established in a review. The purpose of this systematic review is to evaluate the efficacy and safety of methylxanthines in the treatment of bradyarrhythmias associated with sinus node dysfunction. A systematic review was conducted in accordance with PRISMA guidelines on Embase, PubMed, MEDLINE, Cochrane Central, Web of Science, SciELO, Korean Citation Index, Global Index Medicus, and CINAHL through June 2023. A total of 607 studies were identified through the literature search. After applying the inclusion and exclusion criteria, 14 studies were included in this review. The causes of bradyarrhythmias involving the sinoatrial node included acute cervical spinal cord injury, coronavirus disease of 2019, carotid sinus syncope, chronotropic incompetence, heart transplant, and chronic sinus node dysfunction. Theophylline and aminophylline were shown to be effective for increasing heart rate and reducing the reoccurrence of bradyarrhythmias. The data on symptom resolution was conflicting. While many case studies reported a resolution of symptoms, a randomized controlled trial reported no significant difference in symptom scores between the control, theophylline, and pacemaker groups in the treatment of sick sinus syndrome. The incidence of adverse effects was low across all study designs. The data suggests methylxanthines may be useful as an alternative or bridge to nonpharmacologic pacing; however, dosing has yet to be established for various indications. Overall, methylxanthines proved safe and effective as a pharmacologic therapy for bradyarrhythmic manifestations of sinus node dysfunction.

Giant right atrial myxoma presented with symptoms of Budd-Chiari syndrome: a case report

Introduction and importance

Right atrial myxoma is rarely associated with Budd-Chiari syndrome (BCS). In this paper, we present a case of a young patient with a giant right atrial myxoma complicated by the development of BCS.

Case presentation

A 26-year-old female presented to the emergency room with persistent abdominal pain, ascites, lower limb edema, and an acute episode of dyspnea. Abdominal computed tomography revealed a lesion in the right cardiac cavity that resembled an intracardiac thrombus. Transthoracic echocardiography showed a large heterogeneous mass in the right atrium protruding into the right ventricle and a large thrombus interfering with inferior vena cava flow. The patient underwent cardiac surgery to remove the atrial mass, and histopathologic examinations confirmed the diagnosis of atrial myxoma.

Clinical discussion

The right atrial myxoma is relatively rare, especially the giant ones. Rarely have intracardiac tumors such as giant right atrial myxoma been identified as a risk factor for the onset of BCS.

Conclusion

In the differential diagnosis of BCS, right atrial tumors, including myxomas, should be considered, especially when other explanations are absent.

Outcomes in orthotopic heart transplantation following pacemaker implantation

BACKGROUND

Bradyarrhythmias including sinus node dysfunction (SND) and atrioventricular block (AVB) can necessitate pacemaker (PPM) implantation in orthotopic heart transplant (OHT) recipients. Prior studies have shown conflicting findings regarding the effect of PPM implantation on survival. We evaluated the effect of PPM indication on long-term re-transplant-free survival in OHT patients.

METHODS

We conducted a retrospective cohort study of OHT patients at UCLA Medical Center from 1985 to 2018. Indication for PPM (SND, AVB) was identified. Cox proportional hazards model with pacemaker implantation as a time-varying covariate was used to evaluate its effect on the primary endpoint of retransplant or death. We included 1609 OHTs in 1511 adult patients with median follow-up of 12 years.

RESULTS

At transplant, patients were aged 53 ± 13 years and 1125 (74.5%) were male. Pacemakers were implanted in 109 (7.2%) patients; 65 for SND (4.3%) and 43 for AVB (2.8%). Repeat OHT was performed in 103 (6.4%) cases and 798 (52.8%) patients died during the follow-up period. The risk of the primary endpoint was significantly higher in patients requiring PPM for AVB (HR 3.0, 95% CI 2.1-4.2, p < .01) after controlling for age at OHT, gender, hypertension, diabetes, renal disease, history of repeat OHT, acute rejection, transplant coronary vasculopathy, and atrial fibrillation, but not PPM for SND (HR 1.0, 95% CI 0.70-1.4, p = 1.0).

CONCLUSIONS

Patients who required PPM for AVB, but not SND, were at significantly higher risk of death or retransplant compared to patients who did not require PPM.

Non-invasive detection of cardiac allograft rejection among heart transplant recipients using an electrocardiogram based deep learning model

Aims

Current non-invasive screening methods for cardiac allograft rejection have shown limited discrimination and are yet to be broadly integrated into heart transplant care. Given electrocardiogram (ECG) changes have been reported with severe cardiac allograft rejection, this study aimed to develop a deep-learning model, a form of artificial intelligence, to detect allograft rejection using the 12-lead ECG (AI-ECG).

Methods and results

Heart transplant recipients were identified across three Mayo Clinic sites between 1998 and 2021. Twelve-lead digital ECG data and endomyocardial biopsy results were extracted from medical records. Allograft rejection was defined as moderate or severe acute cellular rejection (ACR) based on International Society for Heart and Lung Transplantation guidelines. The extracted data (7590 unique ECG-biopsy pairs, belonging to 1427 patients) was partitioned into training (80%), validation (10%), and test sets (10%) such that each patient was included in only one partition. Model performance metrics were based on the test set (n = 140 patients; 758 ECG-biopsy pairs). The AI-ECG detected ACR with an area under the receiver operating curve (AUC) of 0.84 [95% confidence interval (CI): 0.78-0.90] and 95% (19/20; 95% CI: 75-100%) sensitivity. A prospective proof-of-concept screening study (n = 56; 97 ECG-biopsy pairs) showed the AI-ECG detected ACR with AUC = 0.78 (95% CI: 0.61-0.96) and 100% (2/2; 95% CI: 16-100%) sensitivity.

Conclusion

An AI-ECG model is effective for detection of moderate-to-severe ACR in heart transplant recipients. Our findings could improve transplant care by providing a rapid, non-invasive, and potentially remote screening option for cardiac allograft function.

Transient central hypoxemia due to intermittent high-degree atrioventricular block in a heart-transplanted patient diagnosed during routine electroencephalography: a case report

BACKGROUND

Bradycardia frequently occurs in heart-transplanted patients, mainly as a temporally restricted manifestation early after transplantation and often without symptoms. A high-degree atrioventricular block is mostly symptomatic through cerebral hypoxia induced through cerebral hypoperfusion. Only a few published cases show this specific electroencephalography result in this context. The purpose of this case is to bring attention to atypical manifestations of typical cardiac complications after heart transplantation and the importance of perseverance in the diagnostic.

CASE PRESENTATION

A Central European man in his 50s with history of heart transplantation 31 years previously was admitted to the internal medicine ward for short-lived recurrent episodes of generalized weakness with multiple falls but without loss of consciousness. During routine electroencephalography, the patient perceived this recurrent sensation. This episode coincided with a transient third-degree atrioventricular block followed 8-10 seconds later by a generalized slowing of the electroencephalography, reflecting cerebral hypoxia due to cerebral hypoperfusion. Holter monitoring confirmed the diagnosis. A pacemaker was implanted, consequently resolving the episodes.

CONCLUSION

This case report illustrates the pathophysiological central hypoxemic origin of episodes of generalized weakness caused by a high-degree atrioventricular block in a patient surviving 29 years after heart transplant. It highlights the benefit of electroencephalography as a diagnostic tool in well-selected patients.

Frequency, Risk Factors, and Clinical Outcomes of Late-Onset Atrial Flutter in Patients after Heart Transplantation

Aims: Atrial flutter (AFL) is a common late-onset complication after heart transplantation (HTX) and is associated with worse clinical outcomes. Methods: This study investigated the frequency, risk factors, and outcomes of late-onset post-transplant AFL. We analyzed 639 adult patients undergoing HTX at the Heidelberg Heart Center between 1989 and 2019. Patients were stratified by diagnosis and type of late-onset post-transplant AFL (>90 days after HTX). Results: A total of 55 patients (8.6%) were diagnosed with late-onset post-transplant AFL, 30 had typical AFL (54.5%) and 25 had atypical AFL (45.5%). Patients with AFL were younger at HTX (p = 0.028), received more biatrial anastomosis (p = 0.001), and presented with moderate or severe tricuspid regurgitation (56.4%). Typical AFL was associated with graft rejection (p = 0.016), whereas atypical AFL was associated with coronary artery disease (p = 0.028) and stent implantation (p = 0.042). Patients with atypical AFL showed a higher all-cause 1-year mortality (p = 0.010) along with a higher rate of graft failure after diagnosis of AFL (p = 0.023). Recurrence of AFL was high (83.6%). Patients with catheter ablation after AFL recurrence had a higher 1-year freedom from AFL (p = 0.003). Conclusions: Patients with late-onset post-transplant AFL were younger at HTX, received more biatrial anastomosis, and showed a higher rate of moderate or severe tricuspid regurgitation. Typical AFL was associated with graft rejection, whereas atypical AFL was associated with myocardial ischemia, graft failure, and mortality. Catheter ablation represents a viable option to avoid further episodes of late-onset AFL after HTX.

Interpretation of Typical and Atypical Atrial Flutters by Precision Electrocardiology Based on Intracardiac Recording

Atrial flutter is a term encompassing multiple clinical entities. Clinical manifestations of these arrhythmias range from typical isthmus-dependent flutter to post-ablation microreentries. Twelve-lead electrocardiogram (ECG) is a diagnostic tool in typical flutter, but it is often unable to clearly localize atrial flutters maintained by more complex reentrant circuits. Electrophysiology study and mapping are able to characterize in fine details all the components of the circuit and determine their electrophysiological properties. Combining these 2 techniques can greatly help in understanding the vectors determining the ECG morphology of the flutter waveforms, increasing the diagnostic usefulness of this tool.

Atrial Flutter in Particular Patient Populations

"Despite being one of the best understood cardiac arrhythmias, the clinical meaning of atrial flutter varies according to the specific context, and its optimal treatment may be limited by both the suboptimal response to rate/rhythm control drugs and by the complexity of the underlying substrate. In this article, we present a state-of-the-art overview of mechanisms, prognostic impact, and medical/interventional management options for atrial flutter in several specific patient populations, including heart failure, cardiomyopathies, muscular dystrophies, posttransplant patients, patients with respiratory disorders, athletes, and subjects with preexcitation, aiming to stimulate further research in this challenging field and facilitate appropriate patient care."

Utilization of Implantable Cardioverter-Defibrillators in Patients With Heart Transplant (from National Inpatient Sample Database)

Heart transplant (HT) recipients represent a unique and vulnerable population in whom medium and long-term outcomes are significantly affected by the risk of arrhythmias and sudden cardiac death. The use of implantable cardioverter-defibrillators (ICDs) in this population remains debated. A retrospective analysis of the National Inpatient Sample data between 2009 and 2018 was conducted. Hospitalization data on patients who underwent HT, or who had a preexisting HT, and who received a new ICD were included (excluding the preexisting ICD). Outcomes assessed included inpatient mortality, length of stay, and inflation-adjusted costs. We explored temporal trends in ICD placement and mean length of stay, and predictors of ICD placement. Between 2009 and 2018, 22,673 hospitalizations were recorded for HT, during which patients either received a concurrent new ICD placement (n = 70 [0.31%]) or no new ICD placement (n = 22,603 [99.7%]). During the same period, 146,555 admissions were recorded in patients with a history of HT. ICD placement in patients with a preexisting HT was associated with significantly higher inflation-adjusted costs ($55,680.7 vs $17,219.2; p <0.001). Predictors of ICD placement in preexisting patients with HT included cardiac arrest during hospitalization (odds ratio [OR]:14.3 [3.5 to 58.6]), drug abuse (OR:6.0 [1.3 to 27.1]), and previous PCI (OR:6.0 [2.1 to 17.3]). In conclusion, ICD placement in patients with HT history was associated with significantly higher inflation-adjusted costs. In patients with HT history, factors predicting ICD placement included cardiac arrest at hospitalization, previous PCI, and drug abuse.

Adult Renal Transplantation in a Patient 28 Years after Heart Transplantation as a Neonate for Hypoplastic Left Heart Syndrome

We present a case of kidney transplantation in a 28-year-old patient who received a heart transplant at 7 weeks of age due to hypoplastic left heart syndrome. The patient's renal insufficiency was the result of chronic immunosuppression and hypertension. The almost 28-year-old graft demonstrated very good function. This patient represents as one of the longest pediatric cardiac graft recipients living without any significant functional limitations.

Cardiac allograft vasculopathy and donor age affecting permanent pacemaker implantation after heart transplantation

Aims

The need for permanent pacemakers (PMs) after heart transplantation (HT) is increasing. The aim was to determine the influence of cardiac allograft vasculopathy (CAV), donor age, and other risk factors on PM implantations early and late after HT and its effect on survival.

Methods and results

A retrospective, single‐centre study was performed including HTs from 1984 to July 2018. Early PM was defined as PM implantation ≤90 days and late PM as PM > 90 days. Risk factors for PM and survival after PM were determined with (time‐dependent) multivariable Cox regression. Out of 720 HTs performed, 62 were excluded (55 mortalities ≤30 days and 7 retransplantations). Of the remaining 658 patients, 95 (14%) needed a PM: 38 (6%) early and 57 (9%) late during follow‐up (median 9.3 years). Early PM risk factors were donor age [hazard ratio (HR) 1.06, P < 0.001], ischaemic time (HR 1.01, P < 0.001), and in adults amiodarone use before HT (HR 2.02, P = 0.045). Late PM risk factors were donor age (HR 1.03, P = 0.024) and CAV (HR 3.59, P < 0.001). Late PM compromised survival (HR 2.05, P < 0.001), while early PM did not (HR 0.77, P = 0.41).

Conclusions

Risk factors for early PM implantation were donor age, ischaemic time, and in adults amiodarone use before HT. Late PM implantation risk factors were donor age and CAV. Late PM diminished survival, which is probably a surrogate marker for underlying progressive cardiac disease.

Atrial fibrillation before heart transplantation is a risk factor for post-transplant atrial fibrillation and mortality

AIMS

Atrial fibrillation (AF) after heart transplantation (HTX) is associated with worse clinical outcomes. The current study aimed to analyse the association between AF before HTX and AF within 30 days after HTX.

METHODS AND RESULTS

This study included 639 adults who received HTX at Heidelberg Heart Center. Patients were subdivided into four groups depending on the status of AF before and after HTX. Analyses comprised recipient and donor data, medication, echocardiographic features, permanent pacemaker implantation, stroke, and mortality after HTX. Three hundred thirty-two patients (52.0%) had neither AF before nor after HTX, 15 patients (2.3%) had no AF before HTX but showed AF after HTX, 219 patients (34.3%) showed AF before HTX but had no AF after HTX, and 73 patients (11.4%) had AF before and after HTX. Patients with AF before and after HTX had a higher 1 year post-transplant mortality (39.7%) than patients without AF before or after HTX (18.1%, P < 0.01). Secondary outcomes showed a higher percentage of enlarged atria, ventricular dysfunction, mitral regurgitation, 1-year stroke, and 1-year permanent pacemaker implantation in patients with AF before and after HTX. Multivariate analysis revealed a six-fold elevated risk for post-transplant AF in patients with AF before HTX (hazard ratio: 6.59, confidence interval: 3.72-11.65; P < 0.01). Further risk factors for post-transplant AF were higher donor age and prolonged ischaemic time, whereas total orthotopic HTX was associated with a two-fold lower risk for post-transplant AF.

CONCLUSIONS

Atrial fibrillation before HTX is a risk factor for post-transplant AF, permanent pacemaker implantation, and mortality after HTX.

Newly acquired complete right bundle branch block early after heart transplantation is associated with lower survival

Aims

Right bundle branch block (RBBB) after heart transplantation (HTX) is a common finding, but its impact on post‐transplant survival remains uncertain. This study investigated the post‐transplant outcomes of patients with complete RBBB (cRBBB) ≤ 30 days after HTX.

Methods

This registry study analysed 639 patients receiving HTX at Heidelberg Heart Center between 1989 and 2019. Patients were stratified by diagnosis of cRBBB ≤ 30 days after HTX. Analysis included recipient and donor data, medication, echocardiographic features, graft rejections, atrial fibrillation, heart rates, permanent pacemaker implantation and mortality after HTX including causes of death.

Results

One hundred thirty‐nine patients showed cRBBB ≤ 30 days after HTX (21.8%), 20 patients with pre‐existing cRBBB in the donor heart (3.2%) and 119 patients with newly acquired cRBBB (18.6%). Patients with newly acquired cRBBB had a worse 1‐year post‐transplant survival (36.1%, P < 0.01) compared with patients with pre‐existing cRBBB (85.0%) or without cRBBB (86.4%), along with a higher percentage of death due to graft failure (P < 0.01). Multivariate analysis indicated cRBBB ≤ 30 days after HTX as significant risk factor for 1‐year mortality after HTX (HR: 2.20; 95% CI: 1.68–2.87; P < 0.01). Secondary outcomes showed a higher rate of an enlarged right atrium (P = 0.01), enlarged right ventricle (P < 0.01), reduced right ventricular function (P < 0.01), 30‐day atrial fibrillation (P < 0.01) and 1‐year permanent pacemaker implantation (P = 0.02) in patients with cRBBB after HTX.

Conclusions

Newly acquired cRBBB early after HTX is associated with increased post‐transplant mortality.

Management of Arrhythmias After Heart Transplant: Current State and Considerations for Future Research

Orthotropic heart transplantation remains the most effective therapy for patients with end-stage heart failure, with a median survival of ≈13 years. Yet, a number of complications are observed after orthotropic heart transplantation, including atrial and ventricular arrhythmias. Several factors contribute to arrhythmias, such as autonomic denervation, effect of the surgical technique, acute and chronic rejection, and transplant vasculopathy among others. To minimize risk of future arrhythmias, the bicaval technique and minimizing ischemic time are current surgical standards. Sinus node dysfunction is the most common indication for early (within 30 days) pacemaker implantation, whereas atrioventricular block incidence increases as time from transplant increases. Atrial fibrillation can occur in the first few weeks following transplantation but is uncommon in the long term unless secondary to a precipitant such as acute rejection. The most common atrial arrhythmias are atrial flutters, which are mainly typical, but atypical circuits can be observed such as those that involve the remnant donor atrium in regions immediately adjacent to the atrioatrial anastomosis suture line. Choosing the appropriate pharmacological therapy requires careful consideration due to the potential interaction with immunosuppressive agents. Despite historical concerns, adenosine is effective and safe at reduced doses if administered under cardiac monitoring. Catheter ablation has emerged as an effective treatment strategy for symptomatic supraventricular tachycardias, including ablation of atypical flutter circuits. Cardiac allograft vasculopathy is an important risk factor for sudden cardiac death, yet the role of prophylactic implantable cardioverter-defibrillator implant for sudden death prevention is unclear. Current indications for implantable cardioverter-defibrillator implantation are as in the nontransplant population. A number of questions for future research are posed.

Heart Transplantation From Brain Dead Donors: A Systematic Review of Animal Models

Despite advances in mechanical circulatory devices and pharmacologic therapies, heart transplantation (HTx) is the definitive and most effective therapy for an important proportion of qualifying patients with end-stage heart failure. However, the demand for donor hearts significantly outweighs the supply. Hearts are sourced from donors following brain death, which exposes donor hearts to substantial pathophysiological perturbations that can influence heart transplant success and recipient survival. Although significant advances in recipient selection, donor and HTx recipient management, immunosuppression, and pretransplant mechanical circulatory support have been achieved, primary graft dysfunction after cardiac transplantation continues to be an important cause of morbidity and mortality. Animal models, when appropriate, can guide/inform medical practice, and fill gaps in knowledge that are unattainable in clinical settings. Consequently, we performed a systematic review of existing animal models that incorporate donor brain death and subsequent HTx and assessed studies for scientific rigor and clinical relevance. Following literature screening via the U.S National Library of Medicine bibliographic database (MEDLINE) and Embase, 29 studies were assessed. Analysis of included studies identified marked heterogeneity in animal models of donor brain death coupled to HTx, with few research groups worldwide identified as utilizing these models. General reporting of important determinants of heart transplant success was mixed, and assessment of posttransplant cardiac function was limited to an invasive technique (pressure-volume analysis), which is limitedly applied in clinical settings. This review highlights translational challenges between available animal models and clinical heart transplant settings that are potentially hindering advancement of this field of investigation.

Radiofrequency ablation of supraventricular arrhythmias after orthotopic heart transplantation: Long-term follow-up of a single-center experience

BACKGROUND

Supraventricular arrhythmias (SVAs), commonly managed with radiofrequency ablation (RFA), may occur after orthotopic heart transplantation (OHT).

METHODS

We retrospectively assessed 514 consecutive patients (pts.) undergoing OHT between January 1990 and July 2016 in a single-center. Patients with SVAs managed with RFA were included. Mechanisms of genesis of SVAs, association with surgical techniques and outcomes, were analyzed.

RESULTS

Of 514 pts undergoing OHT, 53% (272 pts.) were managed with bicaval (BC) technique and 47% (242 pts.) with biatrial (BA) technique. Mean follow-up 10 ± 8.4 years. Nine pts. (1.7%) developed SVA requiring RFA. The BC technique was performed in 4 pts., 3 pts. presented cavotricuspid isthmus-dependent atrial flutter (CTI AFL), and 1 pt. double loop AFL. Five pts. were managed with BA technique, 4 pts. presented CTI AFL, and 1 pt. atrial tachycardia (AT). Mean time between OHT and SVA occurrence was 6.6 ± 5.5 years. The procedure was successful in 89% (8 pts.). Arrhythmia recurrence was seen in 3 pts (37%), all with BA technique.

CONCLUSION

Supraventricular arrhythmias in heart transplantation may be associated with the surgical scar. Identifying the mechanism is vital to choose the appropriate treatment with radiofrequency ablation.

A Tale of 2 Nodes After Orthotopic Heart Transplant

We report the case of a 30-year-old man who underwent orthotopic heart transplant via biatrial anastomosis technique. His post-operative electrocardiogram showed atrial dissociation, which is infrequently seen with newer surgical techniques in heart transplantation. (Level of Difficulty: Advanced.)

Beta-blocker therapy in heart transplant recipients: A review

Beta-blockers are essential drugs for the treatment of many cardiovascular diseases, such as heart failure, acute and chronic ischemic heart disease, tachyarrhythmias, and hypertension. However, these drugs have not been used in cardiac transplant patients for many years owing to the fear that they could reduce cardiac output and functional capacity. In recent years, however, some evidence has shown that even in cardiac transplanted patients, β-blockers are useful and effective in the treatment of sinus tachycardia, supraventricular and ventricular tachyarrhythmias, left ventricular systolic dysfunction, and arterial hypertension. Furthermore, some data have shown that the use of β-blockers is associated with reduced mortality in heart transplant recipients. In this review, we summarize this evidence with particular emphasis on the practical aspects of the use of β-blockers in post-transplantation patients to promote the use of this important class of drugs in clinical practice.

Novel heat shock protein 90 inhibitor improves cardiac recovery in a rodent model of donation after circulatory death

OBJECTIVE

Organ donation after circulatory death (DCD) is a potential solution for the shortage of suitable organs for transplant. Heart transplantation using DCD donors is not frequently performed due to the potential myocardial damage following warm ischemia. Heat shock protein (HSP) 90 has recently been investigated as a novel target to reduce ischemia/reperfusion injury. The objective of this study is to evaluate an innovative HSP90 inhibitor (HSP90i) as a cardioprotective agent in a model of DCD heart.

METHODS

A DCD protocol was initiated in anesthetized Lewis rats by discontinuation of ventilation and confirmation of circulatory death by invasive monitoring. Following 15 minutes of warm ischemia, cardioplegia was perfused for 5 minutes at physiological pressure. DCD hearts were mounted on a Langendorff ex vivo heart perfusion system for reconditioning and functional assessment (60 minutes). HSP90i (0.01 μmol/L) or vehicle was perfused in the cardioplegia and during the first 10 minutes of ex vivo heart perfusion reperfusion. Following assessment, pro-survival pathway signaling was evaluated by western blot or polymerase chain reaction.

RESULTS

Treatment with HSP90i preserved left ventricular contractility (maximum + dP/dt, 2385 ± 249 vs 1745 ± 150 mm Hg/s), relaxation (minimum -dP/dt, -1437 ± 97 vs 1125 ± 85 mm Hg/s), and developed pressure (60.7 ± 5.6 vs 43.9 ± 4.0 mm Hg), when compared with control DCD hearts (All P = .001). Treatment abrogates ischemic injury as demonstrated by a significant reduction of infarct size (2,3,5-triphenyl-tetrazolium chloride staining) of 7 ± 3% versus 19 ± 4% (P = .03), troponin T release, and mRNA expression of Bax/Bcl-2 (P < .05).

CONCLUSIONS

The cardioprotective effects of HSP90i when used following circulatory death might improve transplant organ availability by expanding the use of DCD hearts.

Current pharmacotherapeutic strategies for cardiac arrhythmias in heart failure

Introduction: Heart failure (HF) affects over 6 million Americans and is the most common cause of hospital readmissions in the United States. Cardiac arrhythmias are common comorbidities seen in patients with HF and are associated with an increase in morbidity and mortality. Pharmacotherapeutic agents along with device and ablation therapies are the mainstays of treatment for cardiac arrhythmias in HF.Areas covered: An extensive literature review of articles and clinical trials on PUBMED on the topic of pharmacotherapy for cardiac arrhythmias in heart failure was conducted. This review article summarizes the above literature to describe the prevalence of the various types of arrhythmias in HF, the recommended pharmacotherapies for the treatment of these arrhythmias in HF and the evidence that supports these recommendations.Expert opinion: Cardiac arrhythmias are common in HF and are the leading cause of death in this patient population. The management of cardiac arrhythmias in HF is challenging. Pharmacotherapy is the primary though increasingly adjunctive therapy for most cardiac arrhythmias. Further, antiarrhythmic drugs must be used with caution in this patient population due to their potential adverse effects.

Atrioventricular Block: A Heralding Sign of Cardiac Allograft Rejection

Heart transplantation is the treatment of choice for those with end-stage heart failure. However, despite improvements in immunosuppressive treatment, patients are at significant risk of allograft rejection, especially early after transplantation. Any changes in patient's heart condition including reduced left ventricular ejection fraction, arrhythmia and any types of blocks need attention. Herein we report on a 29-year-old man who underwent heart transplantation 5 years before due to dilated cardiomyopathy. He was on immunosuppressive therapy and was good until one week before his admission, when he felt palpitation. Electrocardiography during palpitation showed a second-degree AV-block with heart rate of 60 beats/min. Echocardiography showed good left ventricular systolic function with no regional wall motion abnormality. The patient referred for coronary angiography and endomyocardial biopsy. The angiography was normal. The biopsy showed rejection compatible with ISHLT grade 2R. After treating the patient with 1.5 g methylprednisolone, the symptoms relieved and the block resolved. Bradycardia and second-degree AV-block late after heart transplantation could be a sign of cardiac allograft rejection and need more evaluation, especially endomyocardial biopsy.

Inhibition of MicroRNA-206 Ameliorates Ischemia-Reperfusion Arrhythmia in a Mouse Model by Targeting Connexin43

Reperfusion arrhythmias (RA) are an important cause of sudden cardiac death and is closely associated with gap junction protein in the heart, connexin 43 (Cx43). This study is aimed at elucidating the molecular association between microRNA-206 (miR-206) and Cx43 in ischemia-reperfusion arrhythmia using experimental animal model. Our results showed that miR-206 inhibitor alleviated ischemia-reperfusion-induced arrhythmias, indicated by the lower extent of changes in heart rate (HR), PR interval, rate pressure product (RPP), and mean arterial pressure (MAP). miR-206 inhibitor also downregulated the serum creatine kinase isoenzyme (CKMB) and cardiac troponin I (cTnI) levels in mice under myocardial ischemia-reperfusion (IR) process. The knockdown of Cx43 inversed the protective effects of miR-206 inhibitor on cardiac arrhythmias. These results supported that inhibition of miR-206 ameliorates ischemia-reperfusion arrhythmia by targeting Cx43, and this miR-206/Cx43 axis could serve as a potential target for the management of ischemic-perfusion arrhythmia.

[Experience of general surgical procedures in patients after heart transplantation]

PURPOSE

To study the frequency of general surgical diseases development snd their features in patients after heart transplantation (HTx).

METHODS

From January 2010 to December 2018 it was performed 112 HTx (mean age - 46.7±14.0 years old; 82 - male, 30 - female). During 30 days after HTx 9 patients died. After discharge all recipients (n=98) were included in dispensary observation list. We retrospectively analyzed patients (n=35) who underwent general surgery manipulations in more than 30 days after HTx. All surgical interventions have been done under the reduction of immunosuppression therapy.

RESULTS

During 9 years of post-heart transplant follow-up 45 surgical interventions were performed, 7% (n=3) of them due to infectious complications, 31% (n=14) - oncology and others (62%, n=28). Most of manipulations were planned (39 from 45, 87%), the following general surgery interven- tions prevailed: laparoscopic cholecystectomy (n=13) and those to remove inguinal and umbilical hernia (n=12). During the 1st year the frequency of diseases required surgical treatment was 26% (n=11), infectious causes took place in 5 patients, non-infectious - in 6. Subsequently the incidence of infectious complications decreased that could be associated with the minimization of immunosuppressive therapy. Oncology was more frequent long-term after HTx - more than 3 years: among them the development of colon polyps prevailed and all recipients underwent polypectomy. There was no impact of age, gender, causes of chronic heart failure, obesity, immunosuppressive regimen (including the induction) on the frequency of general surgery diseases development (p&gt;0.05).

CONCLUSION

Based on our experience, we proposed an algorithm of examination, the features of surgical tactics and preparation for it in heart transplanted recipients are described. The important role of post-heart transplant follow-up in the timely detection of diseases requiring general surgical care is given.

Controversies in the Postoperative Management of the Critically Ill Heart Transplant Patient

Heart transplant recipients are susceptible to a number of complications in the immediate postoperative period. Despite advances in surgical techniques, mechanical circulatory support (MCS), and immunosuppression, evidence supporting optimal management strategies of the critically ill transplant patient is lacking on many fronts. This review identifies some of these controversies with the aim of stimulating further discussion and development into these gray areas.

Management of primary graft failure after heart transplantation: Preoperative risks, perioperative events, and postoperative decisions

Primary graft failure (PGF) after heart transplantation (HT) is a devastating and unexpected event characterized by failure of the graft to adequately support recipient circulation necessitating high doses of vasopressors and inotropes and/or temporary mechanical circulatory support. Although it represents an increasingly common event in the current era, there remains a high degree of variability in prevalence, reported risk factors, and approach to this clinical entity. The purpose of the current review is to highlight preoperative considerations including known incidence and risk factors, perioperative issues involving the identification and management of PGF, and postoperative decisions related to weaning of mechanical circulatory support and titration of immunosuppressive therapy. Lastly, we highlight future directions in PGF research, involving basic and translational research, that have the potential to uncover novel strategies of risk stratification and treatment. CASE: Our patient is a 53-year-old man with end-stage non-ischemic dilated cardiomyopathy complicated by ventricular tachycardia (VT), post-capillary pulmonary hypertension, and renal insufficiency. After progressing to NYHA Class IV symptoms, he underwent implantation of a durable left ventricular assist device (LVAD) as bridge to transplant (BTT). On device support, he developed recurrent VT resulting in multiple defibrillator discharges and hospital admission for intravenous anti-arrhythmic therapy. He is subsequently upgraded to a higher status on the waiting list. A suitable donor is identified, with an appropriate predicted heart mass and an anticipated ischemic time of <4 hours. He is taken to the operating room, where at the time of anesthesia induction he develops vasodilatory shock, requiring high-dose vasopressors, and cardiopulmonary bypass (CPB) support for dissection. After surgical anastomosis, cross clamp removal and reperfusion, graft function is extremely poor, there is significant bradycardia requiring pacing, and the patient is unable to be weaned successfully from CPB. Venoarterial extracorporeal membrane oxygenation (VA-ECMO) is initiated, and the patient is transferred to the intensive care unit. Retrospective flow crossmatch is negative. This patient is suffering from severe primary graft failure.

Left atrial appendage occlusion using a Watchman device in a transplanted heart with biatrial anastomosis

A percutaneous left atrial appendage (LAA) occlusion using a Watchman device was performed in a patient with prior biatrial anastomosis orthotopic heart transplant (OHT). Due to the anatomical changes following biatrial anastomosis, transesophageal echocardiography (TEE) imaging and transseptal puncture become technically challenging. We describe how the standard LAA views on TEE were obtained for device sizing, and how the transseptal puncture was modified to cross the scarred septum. This case demonstrates that LAA occlusion using a Watchman device in biatrial anastomosis OHT is safe and can successfully be done.

Heart Rhythm Insights Into Structural Remodeling in Atrial Tissue: Timed Automata Approach

The heart rhythm of a person following heart transplantation (HTX) is assumed to display an intrinsic cardiac rhythm because it is significantly less influenced by the autonomic nervous system-the main source of heart rate variability in healthy people. Therefore, such a rhythm provides evidence for arrhythmogenic processes developing, usually silently, in the cardiac tissue. A model is proposed to simulate alterations in the cardiac tissue and to observe the effects of these changes on the resulting heart rhythm. The hybrid automata framework used makes it possible to represent reliably and simulate efficiently both the electrophysiology of a cardiac cell and the tissue organization. The curve fitting method used in the design of the hybrid automaton cycle follows the well-recognized physiological phases of the atrial myocyte membrane excitation. Moreover, knowledge of the complex architecture of the right atrium, the ability of the almost free design of intercellular connections makes the automata approach the only one possible. Two particular aspects are investigated: impairment of the impulse transmission between cells and structural changes in intercellular connections. The first aspect models the observed fatigue of cells due to specific cardiac tissue diseases. The second aspect simulates the increase in collagen deposition with aging. Finally, heart rhythms arising from the model are validated with the sinus heart rhythms recorded in HTX patients. The modulation in the impairment of the impulse transmission between cells reveals qualitatively the abnormally high heart rate variability observed in patients living long after HTX.

Antiarrhythmic effect of sevoflurane as an additive to HTK solution on reperfusion arrhythmias induced by hypothermia and ischaemia is associated with the phosphorylation of connexin 43 at serine 368

Background

Reperfusion ventricular arrhythmia (RA) associated with hypothermic ischaemic storage is increasingly recognized as a substantial contributor to adverse consequences after heart transplantation. Ischemia- or hypothermia-induced gap junction (GJ) remodelling is closely linked to RA. Reducing GJ remodelling contributes to RA attenuation and is important in heart transplantation. However, sevoflurane has an antiarrhythmic effect associated with the connexin 43 (Cx43) protein that has not yet been fully established.

Methods

Hearts were divided into two groups according to a random number table: all hearts were arrested by an infusion of histidine-tryptophan-ketoglutarate (HTK) solution (4 °C) followed by (1) storage in HTK solution (4 °C) alone for 6 h (n = 8, Control group) or (2) storage in HTK solution supplemented with sevoflurane (2.5%) (4 °C) for 6 h (n = 8, Sevo-HTK group). First, the total Cx43 level and the phosphorylation of Cx43 at Ser368 (Cx43-pS368) were assessed by Western blotting, and the distribution of Cx43 was assessed by immunohistochemistry. Second, programmed electrical stimulation (PES) and monophasic action potential (MAP) recording were used to analyse the MAP duration (MAPD), conduction velocity (CV) and transmural repolarization dispersion (TDR). In addition, haematoxylin and eosin (HE) and terminal deoxynucleotidyl transferase-dUTP nick end labelling (TUNEL) staining were individually used to investigate the degree of myocardial pathological damage and cell apoptosis. Finally, bipolar electrograms were used to record the graft re-beating time and monitor RA during reperfusion for 15 to 30 min.

Results

Sevo-HTK solution relatively increased the total Cx43 (P < 0.01) and Cx43-pS368 (P < 0.01) levels and prevented Cx43 redistribution (P < 0.05) and CV slowing (P < 0.001) but did not change TDR (P > 0.05). Additionally, the Cx43-pS368/total Cx43 ratio (P>0.05) was similar in the two groups. However, with Sevo-HTK solution, the graft re-beating times were shortened, myocardial pathological damage was ameliorated, and the number of apoptotic cells was markedly decreased.

Conclusion

The reduction in hypothermia and ischaemia-induced reperfusion arrhythmias by the addition of sevoflurane to HTK solution may be related to the phosphorylation of Cx43 at serine 368.

Risk of new-onset atrial fibrillation among heart, kidney and liver transplant recipients: insights from a national cohort study

The objective of the study was to explore the incidence of atrial fibrillation (AF) in various populations of patients with organ transplantation (OT). We used a large national data set from Taiwan to investigate the incidence of AF after OT. Frequency matching method used to match controls: OT patients were 4:1. Kaplan-Meier analyses with the use of the Aalen-Johansen estimator was employed for estimating the cumulative incidences of new-onset AF. The Fine-Gray competing risks model was also employed to analyze the risk of AF for the OT cohort compared with the non-OT cohort. 6955 OT patients and 27,820 controls were included in this study. OT did lead to a 3.09-fold risk for AF [95% confidence interval (CI) = 2.07-4.62], especially in the subgroup of female gender [adjusted subhazard ratio (aSHR) = 6.66, 95% CI = 3.85-11.5], age ≤ 49 years (aSHR = 8.19, 95% CI = 3.99-16.8) and without comorbidity (aSHR = 4.61, 95% CI = 2.71-7.87). Moreover, liver recipients tended to be more likely to develop new-onset AF among those OT patients (aSHR = 4.07, 95% CI = 2.63-6.30) as compared to the controls. This study demonstrates an increased incidence of AF after OT. Heightened awareness and clinician vigilance are warranted to facilitate early diagnosis and improved outcomes.

Ageing, the autonomic nervous system and arrhythmia: From brain to heart

An ageing myocardium possesses significant electrophysiological alterations that predisposes the elderly patient to arrhythmic risk. Whilst these alterations are intrinsic to the cardiac myocytes, they are modulated by the cardiac autonomic nervous system (ANS) and consequently, ageing of the cardiac ANS is fundamental to the development of arrhythmias. A systems-based approach that incorporates the influence of the cardiac ANS could lead to better mechanistic understanding of how arrhythmogenic triggers and substrates interact spatially and temporally to produce sustained arrhythmia and why its incidence increases with age. Despite the existence of physiological oscillations of ANS activity on the heart, pathological oscillations can lead to defective activation and recovery properties of the myocardium. Such changes can be attributable to the decrease in functionality and structural alterations to ANS specific receptors in the myocardium with age. These altered ANS adaptive responses can occur either as a normal ageing process or accelerated in the presence of specific cardiac pathologies, such as genetic mutations or neurodegenerative conditions. Targeted intervention that seek to manipulate the ageing ANS influence on the myocardium may prove to be an efficacious approach for the management of arrhythmia in the ageing population.

Atrial fibrillation following heart transplantation: A systematic review and meta-analysis of observational studies

OBJECTIVE

Previous studies have suggested a high incidence of atrial fibrillation (AF) in heart transplant recipients. However, incidence trends of AF in heart transplant recipients remain unclear. The study's aims were (1) to investigate the pooled incidence/incidence trends of AF following heart transplantation and (2) to assess the mortality risk of heart transplant recipients with AF.

METHODS

A literature search for studies that reported the incidence of AF following heart transplantation was conducted using MEDLINE, EMBASE, and The Cochrane Database from inception through March 2018. Pooled incidence and odds ratios (OR) with 95%CI were calculated using a random-effects model.

RESULTS

Eighteen studies (2 cohorts from clinical trials and 16 cohort studies) with 5393 heart transplant recipients were enrolled. The pooled estimated incidence of AF in heart transplant was 10.1% (95%CI: 7.6%-13.2%). Meta-analysis based on the type of anastomotic technique demonstrated a pooled estimated incidence of AF following heart transplantation of 18.7% (95%CI: 10.3%-31.5%) and 11.1% (95%CI: 6.5%-18.4%) by biatrial and bicaval techniques, respectively. There was a significant association between AF following a heart transplant and increased mortality risk with a pooled OR of 2.86 (95%CI: 2.08-3.93). Meta-regression analyses showed no significant correlations between the year of study and incidence of AF (P = 0.47) or mortality risk of AF after heart transplantation (P = 0.99).

CONCLUSIONS

The overall estimated incidence of AF following heart transplantation is 10.1%. There is a significant association between AF and increased mortality after transplantation. Furthermore, incidence and mortality risk of AF following heart transplant does not seem to decrease over time.