Optimal cardiac pacing after heart transplantation

Leadless pacemaker in heart transplantation: a case report and literature review

Our case demonstrates the safe and effective use of a leadless pacemaker in a heart transplant recipient. A man in his 60s with a history of heart transplantation with biatrial anastomosis 7 months prior presented to the emergency department after several syncopal episodes. Telemetry monitoring revealed a paroxysmal complete atrioventricular block. Given his immunocompromised state and prior dual chamber pacemaker extraction at the time of heart transplantation, the patient underwent successful implantation of a leadless pacemaker. Over the past 5 years since device implantation, the patient has not had any syncopal events nor has he had any device-related complications, such as infection.

Permanent pacing in a very long-term follow-up after orthotopic heart transplantation: A matter of when or why?

Background

Orthotopic heart transplantation (OHT) is associated with a high incidence of conduction disturbances (CD) leading to permanent pacemaker (PPM) implantation. However, the improved posttransplant survival raises the question about the pacemaker dependence (PD) in a prolonged follow‐up.

Hypothesis

The prevalence of PPM in OHT is high but not all patients are PD in a very long‐term follow‐up. Device implantation has no prognostic relevance.

Methods

We performed a retrospective analysis of patient medical records focusing on device interrogation data at the most recent follow‐up.

Results

The study population consisted of 183 patients with a mean follow‐up of 15.0 ± 6.8 years. One‐fourth of the patients had undergone PPM implantation (n = 49, 26.8%). Among these, two‐thirds were PD at last follow‐up (n = 32, 65.3%). PPM was more often in biatrial OHT and cardiac allograft vasculopathy (OR 3.0, 95% CI 1.26–7.29, p = .013 and OR 2.0, 95% CI 1.03–3.87, p = .041, respectively). Early sinus node dysfunction (SND) was the most persistent CD. PPM was associated with a poorer outcome in OHT (HR 1.9, 95% CI 1.06–3.46, p = .031) and a higher rate of fatal septicemia (HR 5.1, 95% CI 1.41–18.14, p = .013).

Conclusions

One‐fourth of the OHT recipients develop CD requiring PPM implantation, although one‐third among these are not PD in follow‐up. Early SND is associated with a higher rate of PD. PPM is associated with an inferior prognosis.

Cardiac Implantable Electronic Devices Following Heart Transplantation

Permanent pacemaker (PPM) implantation is required in a subset of patients (∼10%) for sinus node dysfunction or atrioventricular block both early and late after heart transplantation. The incidence of PPM implantation has decreased to <5% with the advent of bicaval anastamosis transplantation surgery. Pacing dependence upon follow-up has been variably reported. An even smaller percentage of transplantation recipients (1.5% to 3.4%) undergo implantable cardioverter-defibrillator (ICD) placement. Rigorous data are lacking for the use of ICDs in the transplantation population and is largely derived from cohort studies and case series. Sudden cardiac death occurs in approximately 10% of transplantation recipients, but multiple nonarrhythmic factors are believed to be responsible, including acute rejection, late graft failure with electromechanical dissociation, and ischemia due to cardiac allograft vasculopathy. This review provides a comprehensive analysis of the existing data regarding the role for PPMs and ICDs in this population, including leadless PPMs and subcutaneous ICDs, special considerations, and future directions.

Chronotropic Incompetence in Chronic Heart Failure

Chronotropic incompetence (CI) is generally defined as the inability to increase the heart rate (HR) adequately during exercise to match cardiac output to metabolic demands. In patients with heart failure (HF), however, this definition is unsuitable because metabolic demands are unmatched to cardiac output in both conditions. Moreover, HR dynamics in patients with HF differ from those in healthy subjects and may be affected by β-blocking medication. Nevertheless, it has been demonstrated that CI in HF is associated with reduced functional capacity and poor survival. During exercise, the normal heart increases both stroke volume and HR, whereas in the failing heart, contractility reserve is lost, thus rendering increases in cardiac output primarily dependent on cardioacceleration. Consequently, insufficient cardioacceleration because of CI may be considered a major limiting factor in the exercise capacity of patients with HF. Despite the profound effects of CI in this specific population, the issue has drawn limited attention during the past years and is often overlooked in clinical practice. This might partly be caused by a lack of standardized approach to diagnose the disease, further complicated by changes in HR dynamics in the HF population, which render reference values derived from a normal population invalid. Cardiac implantable electronic devices (implantable cardioverter defibrillator; cardiac resynchronization therapy) now offer a unique opportunity to study HR dynamics and provide treatment options for CI by rate-adaptive pacing using an incorporated sensor that measures physical activity. This review provides an overview of disease mechanisms, diagnostic strategies, clinical consequences, and state-of-the-art device therapy for CI in HF.

Anesthetic Considerations for the Parturient After Solid Organ Transplantation

Over the past 40 years, the success of organ transplantation has increased such that female solid organ transplant recipients are able to conceive and carry pregnancies successfully to term. Anesthesiologists are faced with the challenge of providing anesthesia care to these high-risk obstetric patients in the peripartum period. Anesthetic considerations include the effects of the physiologic changes of pregnancy on the transplanted organ, graft function in the peripartum period, and the maternal side effects and drug interactions of immunosuppressive agents. These women are at an increased risk of comorbidities and obstetric complications. Anesthetic management should consider the important task of protecting graft function. Optimal care of a woman with a transplanted solid organ involves management by a multidisciplinary team. In this focused review article, we review the anesthetic management of pregnant patients with solid organ transplants of the kidney, liver, heart, or lung.

Correlation of noninvasive markers of cardiac allograft rejection with endomyocardial biopsy: a case report

Although endomyocardial biopsy remains the gold standard to diagnose cardiac allograft rejection, the search continues for clinical parameters that may aid in the early diagnosis of rejection. We report the case of a 29-year-old man who underwent orthotopic heart transplantation and subsequently had multifocal moderate allograft rejection. During the patient's hospital course, he exhibited a number of clinical parameters that served as important clues for the worsening rejection. After aggressive immunosuppression, the improvement of these markers hinted toward his eventual recovery.

Transcellular and paracellular pathways of transepithelial fluid secretion in Malpighian (renal) tubules of the yellow fever mosquito Aedes aegypti

Isolated Malpighian tubules of the yellow fever mosquito secrete NaCl and KCl from the peritubular bath to the tubule lumen via active transport of Na(+) and K(+) by principal cells. Lumen-positive transepithelial voltages are the result. The counter-ion Cl(-) follows passively by electrodiffusion through the paracellular pathway. Water follows by osmosis, but specific routes for water across the epithelium are unknown. Remarkably, the transepithelial secretion of NaCl, KCl and water is driven by a H(+) V-ATPase located in the apical brush border membrane of principal cells and not the canonical Na(+), K(+) -ATPase. A hypothetical cation/H(+) exchanger moves Na(+) and K(+) from the cytoplasm to the tubule lumen. Also remarkable is the dynamic regulation of the paracellular permeability with switch-like speed which mediates in part the post-blood-meal diuresis in mosquitoes. For example, the blood meal the female mosquito takes to nourish her eggs triggers the release of kinin diuretic peptides that (i) increases the Cl(-) conductance of the paracellular pathway and (ii) assembles V(1) and V(0) complexes to activate the H(+) V-ATPase and cation/H(+) exchange close by. Thus, transcellular and paracellular pathways are both stimulated to quickly rid the mosquito of the unwanted salts and water of the blood meal. Stellate cells of the tubule appear to serve a metabolic support role, exporting the HCO(3)(-) generated during stimulated transport activity. Septate junctions define the properties of the paracellular pathway in Malpighian tubules, but the proteins responsible for the permselectivity and barrier functions of the septate junction are unknown.

Permanent pacemaker for syncope after heart transplantation with bicaval technique

Sinus node dysfunction occurs occasionally after heart transplantation and may be caused by surgical trauma, ischemia to the sinus node, rejection, drug therapy, and increasing donor age. However, the timing and indication of permanent pacemaker insertion due to sinus node dysfunction following heart transplantation is contentious. Here, we report a case of a permanent pacemaker insertion for syncope due to sinus arrest after heart transplantation, even with a bicaval technique, which has been known to associate with few incidences of sinus node dysfunction.

Atrial tachyarrhythmias and permanent pacing after pediatric heart transplantation

BACKGROUND

Atrial tachyarrhythmias have been reported in as high as 50% of adult heart recipients. Limited information is available on arrhythmias in pediatric transplant patients. Our objective was to determine the prevalence and significance of atrial tachyarrhythmias and permanent pacing following pediatric heart transplantation.

METHODS

A retrospective review of the medical records, electrocardiograms, and Holter recordings of all consecutive patients following heart transplantation at Children's Hospital, Boston (n = 104) and Lucile Packard Children's Hospital, Stanford (n = 123) was performed. The study group consisted of 227 patients with a median age at transplant of 10.2 yrs (1 day-23.3 yrs).

RESULTS

Atrial tachyarrhythmias occurred in 32 patients (14%) at a median of 15 days post-transplant (1 day-9.2 yrs) and included atrial flutter (n = 13), atrial fibrillation (n = 7), ectopic atrial tachycardia (n = 5), atrioventricular reciprocating tachycardia or atrioventricular node reentry (n = 5), and other (n = 2). Atrial flutter was the only tachyarrhythmia associated with allograft rejection (6/13 atrial flutter vs. 0/7 atrial fibrillation vs. 0/5 ectopic atrial tachycardia, p = 0.03). Patients with atrial fibrillation had a 2.5 fold (95%CI 1.7-3.5) higher risk of death or retransplant compared to patients without atrial fibrillation. Ectopic atrial tachycardia tended to occur in younger recipients compared to atrial fibrillation and flutter (2.7 yrs vs 18.6 yrs and 8.5 yrs respectively, p = 0.06) and was associated with a benign clinical course. There was no association between atrial tachyarrhythmias and graft ischemic time, surgical technique, or coronary artery disease. Pacemakers were required in 12 patients (5.2%), 7 with sinus node dysfunction and 5 for intermittent complete atrioventricular block. There was no consistent association between the need for permanent pacing and coronary artery disease, rejection, or surgical technique.

CONCLUSIONS

Atrial tachyarrhythmias and permanent pacing were uncommon in this cohort of pediatric heart transplant recipients. Association with cardiac rejection, clinical course, and mortality varied depending on the tachyarrhythmia mechanism.

Sinus node dysfunction in a heart transplant patient secondary to severe sinus node artery obstruction--a case report

A case of sinus node dysfunction is reported secondary to severe sinus node artery obstruction 3 years after orthotopic heart transplantation. The patient first presented with frequent dizzy spells and presyncopal episodes for 3 months and then recurrent syncope in the presence of an acute myocardial infarction. Coronary angiography showed a diffusely narrowed sinus node artery without any apparent collateral vessels. The sinus node artery had had only minimal distal disease 3 months previously. A dual chamber permanent pacemaker was implanted with significant improvement in clinical symptoms.

Relative perioperative bradycardia does not lead to adverse outcomes after cardiac transplantation

Since the effects of bradycardia after cardiac transplantation are not known, we tested the hypothesis that perioperative bradycardia would lead to an increase in adverse outcomes after cardiac transplantation. We conducted a retrospective case control study with inclusion criterion of a heart rate (HR) less than 80 bpm during the 1st week after transplantation. Control patients were matched for gender, age and time since transplantation. We identified 34 patients as having perioperative bradycardia out of the 174 who underwent cardiac transplantation between 1994 and 1997. The results demonstrated no significant differences in donor ischemic times (180 vs. 183, p = 0.88), operative surgeon (p = 0.62) or pretransplant cardiac disease (p = 0.81) between groups. Bradycardic patients were more likely to be on pretransplant amiodarone (RR = 20.4, p < 0.001). Perioperative bradycardia did not lead to increases in cellular rejection (p = 0.72) or vasculopathy (p = 0.79). The patients prescribed pretransplant amiodarone (n = 14) had a trend toward delayed time to first rejection episode (31.0 vs. 15.5 days, median, p = 0.07). In conclusion, perioperative bradycardia does not increase adverse outcomes after cardiac transplantation and is associated with pretransplant use of amiodarone. Amiodarone may modify the recipients' immune response by delaying the occurrence of rejection.

Cardiac pacemakers in the transplanted heart: short term with the biatrial anastomosis and unnecessary with the bicaval anastomosis

Sinus node dysfunction occurs commonly after orthotopic heart transplantation and may be caused by surgical trauma, ischemia to the sinus node, rejection, drug therapy and increasing donor age. In the past, using the standard biatrial technique described originally by Lower and Shumway, many series have reported permanent pacing in more than 10% of patients. Unlike sinus node dysfunction in nontransplanted patients, which typically worsens with time, sinus node dysfunction in the transplanted heart usually improves over a period of weeks to months. Delaying the implantation of a permanent pacemaker may render it unnecessary. The development of the bicaval technique for implantation of the donor heart appears to have decreased even further or even eliminated the need for early permanent pacing. Because sinus node dysfunction in the transplanted heart does not predict subsequent development of atrioventricular (AV) node dysfunction, rate-responsive atrial pacing should be used in the majority of cases. Even after appropriate pacing for sinus node dysfunction, the sinus node may recover and permanent pacing may be discontinued. AV conduction abnormalities are far less common and generally occur late after transplantation. Dual-chamber pacing is required and permanent pacing should be continued indefinitely.