Heart transplantation: echocardiographic assessment of morphology and function after more than 10 years of follow-up

A Comprehensive Excursus of the Roles of Echocardiography in Heart Transplantation Follow-Up

Current guidelines for the care of heart transplantation recipients recommend routine endomyocardial biopsy and invasive coronary angiography as the cornerstones in the surveillance for acute rejection (AR) and coronary allograft vasculopathy (CAV). Non-invasive tools, including coronary computed tomography angiography and cardiac magnetic resonance, have been introduced into guidelines without roles of their own as gold standards. These techniques also carry the risk of contrast-related kidney injury. There is a need to explore non-invasive approaches providing valuable information while minimizing risks and allowing their application independently of patient comorbidities. Echocardiographic examination can be performed at bedside, serially repeated, and does not carry the burden of contrast-related kidney injury and procedure-related risk. It provides comprehensive assessment of cardiac morphology and function. Advanced echocardiography techniques, including Doppler tissue imaging and strain imaging, may be sensitive tools for the detection of minor myocardial dysfunction, thus providing insight into early detection of AR and CAV. Stress echocardiography may offer a valuable tool in the detection of CAV, while the assessment of coronary flow reserve can unravel coronary microvascular impairment and add prognostic value to conventional stress echocardiography. The review highlights the role of Doppler echocardiography in heart transplantation follow-up, weighting advantages and limitations of the different techniques.

Insight into Noninvasive Radiological Modalities to Detect Heart Transplant Rejection

Purpose Patients with end-stage heart failure who remain symptomatic even with exemplary medical and device therapy are treated with heart transplantation. Multitudes of endeavor have been contrived during the last decennium in the field of noninvasive tests to rule out heart transplant rejection (HTR). In spite of having supportive literature, noninvasive imaging techniques lack acceptable documentation of clinical robustness, and endomyocardial biopsy (EMB) still remains the gold standard. The aim of this review is to shed light on the existing noninvasive radiological modalities to detect rejection among heart transplant recipients.

Methods A comprehensive search was conducted for this review article on the basis of literature available including scientific databases of PubMed, Embase, and Google Scholar, using keywords of “Heart transplantation,” “Acute allograft rejection,” “Arrhythmias,” “Echocardiography,” “Speckle tracking echocardiography,” and “Cardiac magnetic resonance imaging” from inception until September 2020.

Results After preliminary screening of the databases, details regarding existent noninvasive radiological modalities to detect HTR were gathered and compiled in this review article. Currently, deformation imaging using speckle tracking and T2 time using cardiac magnetic resonance imaging can serve as screening tools based on which further invasive investigations can be planned. Standardization of blood-based and imaging modalities as screening and possible diagnostic tools for rejection would have obvious clinical and financial benefits in the care of growing number of post heart transplant recipients in our country.

Conclusion Diagnosis of allograft rejection in heart transplant recipients through noninvasive techniques is demanding. To unravel the potential of noninvasive radiological modalities that can serve as a standard-of-care test, a prospective multicentric study randomizing noninvasive modality as first strategy versus current EMB-based gold standard of care is the need of the hour.

The Role of Echocardiography in the Management of Heart Transplant Recipients

Transthoracic echocardiography is the primary non-invasive modality for the investigation of heart transplant recipients. It is a versatile tool that provides comprehensive information on cardiac structure and function. Echocardiography is also helpful in diagnosing primary graft dysfunction and evaluating the effectiveness of therapeutic approaches for this condition. In acute rejection, echocardiography is useful with suspected cellular or antibody-mediated rejection, with findings confirmed and quantified by endomyocardial biopsy. For identifying chronic rejection, ultrasound has a more significant role and, in some specific patients (e.g., patients with renal failure), it may offer a role comparable to coronary angiography to identify cardiac allograft vasculopathy. This review highlights the usefulness of echocardiography in evaluating normal graft function and its role in the management of heart transplant recipients.

Exercise training in heart transplantation

Heart transplantation remains the gold standard in the treatment of end-stage heart failure (HF). Heart transplantation patients present lower exercise capacity due to cardiovascular and musculoskeletal alterations leading thus to poor quality of life and reduction in the ability of daily self-service. Impaired vascular function and diastolic dysfunction cause lower cardiac output while decreased skeletal muscle oxidative fibers, enzymes and capillarity cause arteriovenous oxygen difference, leading thus to decreased peak oxygen uptake in heart transplant recipients. Exercise training improves exercise capacity, cardiac and vascular endothelial function in heart transplant recipients. Pre-rehabilitation regular aerobic or combined exercise is beneficial for patients with end-stage HF awaiting heart transplantation in order to maintain a higher fitness level and reduce complications afterwards like intensive care unit acquired weakness or cardiac cachexia. All hospitalized patients after heart transplantation should be referred to early mobilization of skeletal muscles through kinesiotherapy of the upper and lower limbs and respiratory physiotherapy in order to prevent infections of the respiratory system prior to hospital discharge. Moreover, all heart transplant recipients after hospital discharge who have not already participated in an early cardiac rehabilitation program should be referred to a rehabilitation center by their health care provider. Although high intensity interval training seems to have more benefits than moderate intensity continuous training, especially in stable transplant patients, individualized training based on the abilities and needs of each patient still remains the most appropriate approach. Cardiac rehabilitation appears to be safe in heart transplant patients. However, long-term follow-up data is incomplete and, therefore, further high quality and adequately-powered studies are needed to demonstrate the long-term benefits of exercise training in this population.

Coronary imaging of cardiac allograft vasculopathy predicts current and future deterioration of left ventricular function in patients with orthotopic heart transplantation

BACKGROUND

Intravascular ultrasound (IVUS) and optical coherence tomography (OCT) improve sensitivity of cardiac allograft vasculopathy (CAV) detection compared to invasive coronary angiography (ICA), but their ability to predict clinical events is unknown. We determined whether severe CAV detected with ICA, IVUS, or OCT correlates with graft function.

METHODS

Comparison of specific vessel parameters between IVUS and OCT on 20 patients attending for angiography 12-24 months post-orthotopic heart transplant. Serial left ventricular ejection fraction (EF) was recorded prospectively.

RESULTS

Analyzing 55 coronary arteries, OCT and IVUS correlated well for vessel CAV characteristics. A mean intimal thickness (MIT)_OCT  > .25 mm had a sensitivity of 86.7% and specificity of 74.3% at detecting Stanford grade 4 CAV. Those with angiographically evident CAV had significant reduction in graft EF over 7.3 years follow-up (median ΔEF -2% vs +1.5%, P = .03). Patients with MIT_OCT  > .25 mm in at least one vessel had a lower median EF at time of surveillance (57% vs 62%, P = .014). Two MACEs were noted.

CONCLUSION

Imaging with OCT correlates well with IVUS for CAV detection. Combined angiography and OCT to screen for CAV within 12-24 months of transplant predicts concurrent and future deterioration in graft function.

Assessment of biventricular function by three-dimensional speckle-tracking echocardiography in clinically well pediatric heart transplantation patients

BACKGROUND

The biventricular function plays an important role in the prognosis of pediatric heart transplantation (HTx) patients. Therefore, in this study, we aimed to evaluate the biventricular function of pediatric HTx patients by three-dimensional (3D) speckle-tracking echocardiography (3D-STE).

METHODS

We enrolled 30 clinically well pediatric HTx patients and 30 healthy controls with a similar distribution of sex and age to the HTx. All participants underwent comprehensive two-dimensional (2D) and 3D echocardiography. Left ventricular (LV) global longitudinal strain (GLS), global circumferential strain (GCS), left and right ventricular ejection fraction (LVEF and RVEF, respectively), and right ventricular free wall longitudinal strain (RV FWLS) were acquired by 3D-STE. Moreover, the correlations between strains and clinical data were explored.

RESULTS

Compared with controls, LV GLS was decreased in pediatric HTx patients (P < .05), while LV GCS and LVEF showed no difference. LV GLS showed a weak correlation with cold ischemic time in HTx group (r = 0.396, P < .05). Meanwhile, RVEF and RV FWLS were significantly lower in the HTx group (P < .05). In the HTx group, RV FWLS showed a weak correlation with the preoperative mean pulmonary artery pressure (r = 0.420, P < .05) and postoperative pulmonary artery systolic pressure (r = 0.465, P < .05).

CONCLUSION

The 3D-biventricular mechanical functions were decreased in clinically well pediatric HTx patients. The provided characteristics and appropriate normal values of biventricular mechanical functions can be the basis in subsequent studies in the pediatric HTx patients.

Right Ventricular Dysfunction as an Echocardiographic Measure of Acute Rejection Following Heart Transplantation in Children

Noninvasive biomarkers of acute allograft rejection (AAR) following orthotopic heart transplantation (OHT) are needed. The aim of this study was to investigate the accuracy of echocardiographic (ECHO) right ventricular (RV) global functional and resistance indices in the detection of AAR. This retrospective chart review included children with biopsy-proven AAR (grade ≥ 2R cellular or CD4 + antibody-mediated rejection) following OHT and an ECHO within 12 h of the biopsy. ECHO measures: (a) ratio of systolic to diastolic duration (S/D), (b) RV myocardial performance index (MPI) and (c) tricuspid regurgitant gradient to RV outflow tract velocity time integral ratio (TRG/VTI), were derived at baseline, during AAR and at two follow-ups. Sixteen patients [56% male, mean (SD) age at OHT 3.5 (4.3) years] had 16 AAR episodes. S/D (1.15 vs. 1.60, p < 0.01), RV MPI (0.19 vs. 0.39, p < 0.01) and TRG/VTI (1.05 vs. 1.7, p = 0.01) deteriorated during AAR and, except for diastolic duration, improved significantly at first follow-up. The negative predictive values for S/D, RV MPI and TRG/VTI at cutoffs of 1.3, 0.31 and 1.3 were 97, 97 and 87%, respectively. RV S/D, MPI and TRG/VTI deteriorated during AAR. Their excellent negative predictive values suggest that their incorporation in surveillance may obviate the need for routine biopsies.

Surgery-related complications in cardiac transplantation patients

OBJECTIVE

The surgical techniques was first described by Lower and Shumway for cardiac transplantation have not changed for many years; they are still being commonly used worldwide despite recently presented alternatives. We sought to evaluate the surgical complications among our cardiac transplantation patients in whom we performed the standard technique.

PATIENTS AND METHODS

The standard biatrial anastomosis technique was used in 13 patients who have a mean follow-up of 18.6 (1 to 38) months. During the follow-up, echocardiographic assessment was performed to evaluate left and right atrial diameters, tricuspid and mitral valve regurgitation, interatrial septum, and suture lines. Elecotrocardiograms were evaluated for arryhthmia and pacemaker requirements in the midterm.

RESULTS

The mean left and right atrial diameters were measured as 40.5 (32 to 57) x 66.6 (48 to 78) and 37.9 (32 to 43) x 56.3 (48 to 69) mm, respectively. The jet area was calculated at less than 5 cm(2) for mitral and tricuspid valve regurgitation, which can be defined as "mild" regurgitation. There was no increase in the degree of regurgitation of both atrioventricular valves during the follow-up period. In one patient, a thrombus was detected in the suture line; there was a nonsignificant left to right shunt in another patient. A temporary pacemaker was indicated in two patients. Atrial fibrillation was detected in three patients, who responded to medical therapy. During the follow-up atrial fibrillation developed in one patient.

CONCLUSION

The cardiac transplantation operation using the standard technique may result in atrial dysfuntion due to deformation of atrial integrity and geometry. However, when we evaluated our results, we concluded that the standard surgical technique was a safe, simple, effective, and feasible method.

Usefulness and limitations of transthoracic echocardiography in heart transplantation recipients

Transthoracic echocardiography is a primary non-invasive modality for investigation of heart transplant recipients. It is a versatile tool which provides comprehensive information about cardiac structure and function. Echocardiographic examinations can be easily performed at the bedside and serially repeated without any patient's discomfort. This review highlights the usefulness of Doppler echocardiography in the assessment of left ventricular and right ventricular systolic and diastolic function, of left ventricular mass, valvular heart disease, pulmonary arterial hypertension and pericardial effusion in heart transplant recipients. The main experiences performed by either standard Doppler echocardiography and new high-tech ultrasound technologies are summarised, pointing out advantages and limitations of the described techniques in diagnosing acute allograft rejection and cardiac graft vasculopathy. Despite the sustained efforts of echocardiographic technique in predicting the biopsy state, endocardial myocardial biopsies are still regarded as the gold standard for detection of acute allograft rejection. Conversely, stress echocardiography is able to identify accurately cardiac graft vasculopathy and has a recognised prognostic in this clinical setting. A normal stress-echo justifies postponement of invasive studies. Another use of transthoracic echocardiography is the monitorisation and the visualisation of the catheter during the performance of endomyocardial biopsy. Bedside stress echocardiography is even useful to select appropriately heart donors with brain death. The ultrasound monitoring is simple and effective for monitoring a safe performance of biopsy procedures.

Influence of different implantation techniques on long-term survival after orthotopic heart transplantation: an echocardiographic study

BACKGROUND

Orthotopic heart transplantation (OHT) was initially done by the biatrial technique, although the bicaval technique has recently become more popular. The aim of this study was to compare OHT outcomes when using the bicaval technique vs the biatrial technique.

METHODS

A total of 615 patients were transplanted at the Cleveland Clinic Foundation from January 1993 and October 2003 (biatrial technique: n = 293; bicaval technique: n = 322). The average follow-up period was 4.2 +/- 2.9 years (range 1 to 11 years). Patients who were supported with a left ventricular assist device (prior to transplant) and who could not be weaned off respiratory support were excluded.

RESULTS

Patients in both groups were similar with regard to pre-operative characteristics. The peri-operative mortality showed no statistical significant differences between the two groups. The left atrium was significantly more enlarged in the biatrial group. The bicaval group showed a significantly reduced incidence of tricuspid regurgitation. Survival at 10-year follow-up was 87.3% in the bicaval group and 79.9% in the biatrial group (p < 0.05). Left ventricular ejection fraction (LVEF), right ventricular ejection fraction (RVEF) and moderate to severe tricuspid regurgitation were significant risk factors for death in both groups. The bicaval technique showed a significantly better mortality outcome.

CONCLUSIONS

This study showed that the bicaval technique for OHT offers a better outcome than the biatrial technique. The significant reduction of left atrial size and atrioventricular valve regurgitation in the bicaval group may have a major impact on the long-term preservation of cardiac function and survival.

Risk stratification for renal transplantation after cardiac or lung transplantation: single-center experience and review of the literature

BACKGROUND

Long-term survival after heart (HTx) or lung (LuTx) transplantation increases the risk for end-stage renal disease (ESRD). After HTx ESRD was reported to enhance mortality, and kidney transplantation (KTx) was shown to improve survival. However, prognostic factors in ESRD after HTx or LuTx are largely unknown.

METHODS

Single-center observational study in HTx and LuTx patients who accessed the KTx waiting list; baseline characteristics were correlated with mortality.

RESULTS

KTx was performed in 15 of 65 study patients. Survival was comparable on the KTx waiting list and in reference patients from the same center without ESRD. KTx significantly improved survival (5 years' survival 84.6% with KTx vs. 56.5% on the KTx waiting list, p = 0.030). None of the baseline parameters predicted mortality in the KTx group. Only on the KTx waiting list BMI (median 24.7 vs. 20.7; p < 0.05) and left ventricular ejection fraction (LVEF, median 63 vs. 53%, p < 0.008) significantly correlated with survival.

CONCLUSIONS

The risk for mortality after HTx or LuTx is not increased by ESRD, provided that patients meet access criteria for the KTx waiting list. KTx improves survival in ESRD after HTx or LuTx. BMI and LVEF may predict outcome in HTx/LuTx patients on the KTx waiting list.

Changes in right ventricular dimensions and performance after passive cardiac containment

BACKGROUND

Previous studies have shown that the cardiac support device (CSD) improves left ventricular structure and function in patients with heart failure by preventing further cardiac enlargement. The aim of this study was to identify effects on the right ventricle (RV).

METHODS

Ten male patients with idiopathic dilated cardiomyopathy underwent electron-beam computed tomographic (CT) examination within 1 month before, and 6 to 9 months after CSD implantation. The RV end-diastolic and end-systolic volumes (EDV, ESV) and diameters (EDD, ESD), stroke volume (SV), ejection fraction (EF), total and forward RV output (RVO, fRVO), and tricuspid regurgitation fraction (TRF) were calculated.

RESULTS

The EDV measurements decreased from 182.1 +/- 49.6 to 137.5 +/- 37.0 mL, ESV from 114.8 +/- 47.0 to 68.3 +/- 23.8 mL, EDD from 48.2 +/- 6.6 to 41.6 +/- 7.1 mm, and ESD from 39.6 +/- 6.9 to 32.7 +/- 6.5 mm (p < 0.05 for each). Ejection fraction increased from 38.5 +/- 8.9 to 52.0% +/- 7.7% and fRVO from 4.0 +/- 0.8 to 4.6 +/- 1.1 L/min (each with p < 0.05). TRF decreased from 18.2 +/- 14.1 to 10.4% +/- 13.5%, whereas SV and RVO remained nearly unchanged. Postoperatively, RV volumes, EF, and fRVO were not different from 15 age- and gender-matched normal control patients.

CONCLUSIONS

Implantation of a CSD leads to a decrease in RV size and improved RV performance. These data together with the results of previous studies demonstrating improved left ventricular structure and function confirm the biventricular nature of recovery with the CSD.

Cardiac changes noted within 4 years of transplant in postmortem evaluation of a patient with untreated obstructive sleep apnea

In this case report, the authors discuss the autopsy findings of biventricular cardiomegaly 4 years after transplantation of an otherwise normal heart in a patient who did not accept treatment for documented severe obstructive sleep apnea.