Serial assessment of left ventricular function and mass after orthotopic heart transplantation: a 4-year longitudinal study

Echocardiographic assessment of pediatric heart transplantation: A single-center experience in China

BACKGROUND

Pediatric heart transplant (HT) has become the standard of care for end-stage heart failure in children worldwide. Serial echocardiographic evaluations of graft anatomy and function during follow-up are crucial for post-HT management. However, evolution of cardiac structure and function after pediatric HT has not been well described, especially during first year post-HT. This study aimed to characterize the evolution of cardiac structure and function after pediatric HT and investigate the correlation between biventricular function with adverse clinical outcomes.

METHODS

A single-center retrospective study of echocardiographic data obtained among 99 pediatric HT patients was conducted. Comprehensive echocardiographic examination was performed in all patients at 1-, 3-, 6-, 9- and 12-months post-HT. We obtained structural, functional and hemodynamic parameters from both left- and right-side heart, such as left ventricular stroke volume (LVSV), left ventricular ejection fraction (LVEF), right ventricular fractional area change (RVFAC), etc. The cardiac evolution of pediatric HT patients during first post-HT year was described and compared between different time points. We also explored the correlation between cardiac function and major adverse transplant events (MATEs).

RESULTS

1) Evolution of left heart parameters: left atrial length, mitral E velocity, E/A ratio, LVSV and LVEF significantly increased while mitral A velocity significantly decreased over the first year after HT (P < .05). Compared with 1 month after HT, interventricular septum (IVS) and left ventricular posterior wall (LVPW) decreased at 3 months but increased afterwards. (2) Evolution of right heart parameters: right ventricular base diameter and mid-diameter; right ventricular length diameter, tricuspid E velocity, E/A ratio, tricuspid annular velocity e' at free wall, and RVFAC increased, while tricuspid A velocity decreased over the first year after HT (P < .05). (3) Univariate logistic regression model suggests that biventricular function parameters at 1-year post-HT (LVEF, RVFAC, tricuspid annular plane systolic excursion and tricuspid lateral annular systolic velocity) were associated with MATEs.

CONCLUSION

Gradual improvement of LV and RV function was seen in pediatric HT patients within the first year. Biventricular function parameters associated with MATEs. The results of this study pave way for designing larger and longer follow-up of this population, potentially aiming at using multiparameter echocardiographic prediction of adverse events.

Impact of gender on echocardiographic characteristics in heart transplant recipients

AIMS

Assessment following heart transplantation (HTx) is routinely performed using transthoracic echocardiography. Differences in long-term mortality following HTx related to donor-recipient matching have been reported, but effects of gender on cardiac size and function are not well studied. The aims of this study were to evaluate differences in echocardiographic characteristics of HTx recipients defined by gender.

METHODS AND RESULTS

The study prospectively enrolled 123 (n = 34 female) HTx recipients of which 23 recipients was donor-recipient gender mismatched. Patients were examined with 2-dimensional echocardiography using Philips iE33 ultrasound system. Data were analysed across strata based on recipient gender and gender mismatch. Male recipients had larger left ventricular (LV) mass, thicker septal wall (P<0·001) and larger absolute LV volumes (P<0·001). Mean LV ejection fraction (EF) was higher in females (P<0·05), but no differences in conventional parameters of right ventricular (RV) function were found. Ventricular strain was higher in females than in males: LV global longitudinal strain (P<0·01), RV global longitudinal strain (P<0·05) and RV lateral free wall (P<0·05). The male group receiving a female donor heart had comparable EF and strain parameters to the female group receiving a gender-matched heart.

CONCLUSION

We found that female recipient gender was associated with smaller chamber size, higher LV EF and better LV and RV longitudinal strain. Gender-mismatched male recipients appeared to exhibit function parameters similar to gender-matched female recipients. Our results indicate that the gender aspect, analogous to current reference guidelines in general population, should be taken into consideration when examining patients post-HTx.

Normal Reference Ranges for Transthoracic Echocardiography Following Heart Transplantation

BACKGROUND

Heart function following heart transplantation (HTx) is influenced by numerous factors. It is typically evaluated using transthoracic echocardiography, but reference values are currently unavailable for this context. The primary aim of the present study was to derive echocardiographic reference values for chamber size and function, including cardiac mechanics, in clinically stable HTx patients.

METHODS

The study enrolled 124 healthy HTx patients examined prospectively. Patients underwent comprehensive two-dimensional echocardiographic examinations according to contemporary guidelines. Results were compared with recognized reference values for healthy subjects.

RESULTS

Compared with guidelines, larger atrial dimensions were seen in HTx patients. Left ventricular (LV) diastolic volume was smaller, and LV wall thickness was increased. With respect to LV function, both ejection fraction (62 ± 7%, P < .01) and global longitudinal strain (-16.5 ± 3.3%, P < .0001) were lower. All measures of right ventricular (RV) size were greater than reference values (P < .0001), and all measures of RV function were reduced (tricuspid annular plane systolic excursion 15 ± 4 mm [P < .0001], RV systolic tissue Doppler velocity 10 ± 6 cm/sec [P < .0001], fractional area change 40 ± 8% [P < .0001], and RV free wall strain -16.9 ± 4.2% [P < .0001]). Ejection fraction and LV global longitudinal strain were significantly lower in patients with previous rejection.

CONCLUSION

The findings of this study indicate that the distribution of routinely used echocardiographic measures differs between stable HTx patients and healthy subjects. In particular, markedly larger RV and atrial volumes and mild reductions in both LV and RV longitudinal strain were evident. The observed differences could be clinically relevant in the assessment of HTx patients, and specific reference values should be applied in this context.

Influence of size disparity of transplanted hearts on cardiac growth in infants and children

OBJECTIVE

We aimed to evaluate the influence of size disparity of the transplanted heart on cardiac growth in infant and child recipients by comparing donor body surface area (BSA) and cardiac dimensions during transplantation to the corresponding parameters of the recipient over a period of time.

METHODS

A retrospective review of medical and echocardiographic records of 147 children (5.3 ± 4.0; median, 4.1; range, 1 month-15 years) who underwent orthotopic heart transplantation was done. The patients were divided into age groups as follows: less than 1 year (n = 23), 1 to 2 years (n = 26), more than 2 to 5 years (n = 18), more than 5 to 10 years (n = 27), and more than 10 to 15 years (n = 53). Donor/recipient BSA ratio was determined during transplantation. Cardiac dimensions were measured 30 days after transplantation and compared at 1 year, 2 to 5 years, and 5 to 10 years after transplantation.

RESULTS

There were no significant differences in the ventricular end-diastolic diameter, volumes, and mass among those with a donor/recipient BSA ratio of less than 0.80, 0.8 to 1.2, and more than 1.2 (P = .80, .44, and .48, respectively). In all the cardiac dimensions and volumes measured, donor-recipient mismatch did not influence the continuous growth of the heart, as indicated by the measured parameters, in accordance with the recipients' increase in BSA over time. All calculated Z-scores at 1 year, 2 to 5 years, and 6 to 10 years after transplantation were normal when indexed to BSA.

CONCLUSIONS

This study demonstrates that despite size disparity of a transplanted heart, it undergoes normal growth in diastolic dimensions, volumes, and myocardial mass over time as appropriate for body growth after cardiac transplantation in infants and children.

Cardiac allograft remodeling after heart transplantation is associated with increased graft vasculopathy and mortality

The aim of this study was to assess the patterns, predictors and outcomes of left ventricular remodeling after heart transplantation (HTX). Routine echocardiographic studies were performed and analyzed at 1 week, 1 year and 3-5 years after HTX in 134 recipients. At each study point the total cohort was divided into three subgroups based on determination of left ventricle mass and relative wall thickness: (1) NG-normal geometry (2) CR-concentric remodeling and (3) CH-concentric hypertrophy. Abnormal left ventricular geometry was found as early as 1 week after HTX in 85% of patients. Explosive mode of donor brain death was the most significant determinant of CH (OR 2.9, p = 0.01) at 1 week. CH at 1 week (OR 2.72, p = 0.01), increased body mass index (OR 1.1, p = 0.01) and cytomegalovirus viremia (OR - 4.06, p = 0.02) were predictors of CH at 1 year. CH of the cardiac allograft at 1 year was associated with increased mortality as compared to NG (RR 1.87, p = 0.03). CR (RR 1.73, p = 0.027) and CH (RR 2.04, p = 0.008) of the cardiac allograft at 1 year is associated with increased subsequent graft arteriosclerosis as compared to NG.

Association between restoration of autonomic modulation in the native sinus node and hemodynamic improvement after cardiac transplantation

BACKGROUND

Little is known about the autonomic control of the native sinus node (NSN) after heart transplantation because its electrical activity is difficult to detect with skin electrodes.

METHODS AND RESULTS

The intracardiac electrogram of the NSN and the donor heart electrocardiogram were measured simultaneously. A total of 351 recordings of 107 heart transplant patients (age 53.6+/-12.3 years) were obtained up to 1 year after transplantation. In a subgroup of 41 patients, consecutive recordings were made. Eleven recordings of heart failure patients (age 56.2+/-6.5 years) awaiting cardiac transplantation were used as controls. To examine a relationship between autonomic indices of the NSN and hemodynamics of the donor heart, intracardiac pressures and cardiac output were recorded in the same session. Heart rate variability (HRV) parameters in time and frequency domain of the NSN showed a significant increase starting at 6 months after transplantation, whereas heart rate of the NSN tended to decrease. Heart rate and HRV parameters remained constant over the first year in the donor heart. Higher values of low-frequency and high-frequency powers in the NSN were associated with lower values of right ventricular, pulmonary artery, and mean atrial pressure and cardiac output. Recordings of patients with rejection could not be distinguished from those without rejection based on the spectral content of HRV of either the NSN or the donor heart.

CONCLUSIONS

These data suggest a restoration of autonomic modulation of the NSN. This restoration is associated with hemodynamic improvement of the donor heart.

Impaired exercise capacity late after cardiac transplantation: influence of chronotropic incompetence, hypertension, and calcium channel blockers

BACKGROUND AND METHODS

Patients undergoing orthotopic cardiac transplantation manifest reduced exercise capacity during the first postoperative year, which is related primarily to chronotropic incompetence of the denervated heart. To determine whether exercise capacity improves during the long term after transplantation, we prospectively studied 45 patients from 1 month to 6 years after cardiac transplantation by use of maximal treadmill exercise testing for measurement of exercise duration, peak heart rate, and peak VO2. All had normal left ventricular ejection fractions. Patients were categorized according to length of time since transplant and compared to 14 untrained normal subjects.

RESULTS

Peak exercise heart rate and exercise duration were progressively higher as time after transplantation increased. However, patients who had undergone transplantation more than 2 years earlier continued to manifest a significant reduction in peak exercise heart rate (157+/-3 beats/min vs 178+/-14 beats/min) and reduced exercise duration (8.6+/-0.5 minutes vs 13.2+/-2.0 minutes) compared with controls. In contrast, peak VO2 was similar at all times after transplant and remained markedly reduced in patients who underwent transplantation more than 2 years earlier as compared with controls (22.1+/-0.7 mL/kg/min vs 42.1+/-9.1 mL/kg/min). The potential effects of 14 clinical variables on exercise performance were evaluated by regression modeling. Patients with poorly controlled hypertension had a shorter median exercise duration (7.4 minutes vs 9.7 minutes) and a lower median peak VO2 (20.3 mL/kg/min vs 23.2 mL/kg/min) compared with patients with normal or well-controlled blood pressure. Patients treated with calcium channel blockers for hypertension had greater chronotropic incompetence during exercise (peak heart rate 139 beats/min vs 158 beats/min). There was no relation between exercise capacity and recipient age, donor age, recipient sex, donor ischemic time, pretransplant diagnosis, length of peritransplant hospitalization, percentage of ideal body weight, left ventricular ejection fraction, frequency or severity of allograft rejection, or long-term use of oral prednisone therapy.

CONCLUSIONS

Exercise capacity, as measured by treadmill exercise time and peak heart rate, improves in the first 2 years after transplantation, but does not reach normal values in patients up to 6 years after transplant. Peak VO2 remains significantly reduced at all times after transplantation despite the presence of normal resting left ventricular systolic function.

Prognostic significance of coronary flow reserve on left ventricular ejection fraction in cardiac transplant recipients

BACKGROUND

Cardiac allograft vasculopathy is a common phenomenon in epicardial and microvascular vessels. Intramyocardial vessel disease may lead to small, stellate infarcts. The present study tested the impact of microvascular vasomotor function on changes in left ventricular systolic function in the long-term follow-up after cardiac transplantation.

METHODS

Seventeen consecutive cardiac transplant patients, 40+/-21 months after cardiac transplantation, without angiographically visible cardiac allograft vasculopathy and without episodes of acute rejection were included in the study. Coronary microvascular reactivity was assessed by the endothelium-dependent stimulus acetylcholine (50 microg i.c.) and by the endothelium-independent stimulus dipyridamole (0.56 mg/kg i.v.) utilizing an Doppler catheter. Radionuclide ventriculography was performed at the time of coronary flow measurement and repeated 2 years later to correlate changes in left ventricular ejection fraction with the coronary flow reserve measurement 2 years previously.

RESULTS

There was a statistically significant correlation between endothelium- independent coronary flow reserve to dipyridamole and changes in ejection fraction at rest (r=0.59; P < 0.01) and during exercise (r=0.48; P < 0.05). Twenty-four months later, patients with a coronary flow reserve to dipyridamole < 2.5 showed a significant decline in ejection fraction during exercise (-7 +/- 5%) compared to patients with a coronary flow reserve > 2.5 (1.1+/-5%; P=0.003). Coronary flow reserve to acetylcholine was not correlated with a reduced ejection fraction during exercise.

CONCLUSIONS

Endothelium-independent microvascular dysfunction has prognostic importance for deterioration of left ventricular function in cardiac transplant recipients without angiographically visible coronary artery stenoses. These results reinforce the concept that microvascular and epicardial vessel disease after transplantation are two distinct entities with different functional consequences.

Cyclosporine-induced hypertension in cardiac transplantation

Cyclosporine-induced hypertension occurs in more than 90% of patients following cardiac transplantation. This article underlines the clinical characteristics as well as the mechanisms that can be associated with the development of cyclosporine-induced hypertension. In addition, the clinical trials up to date for the treatment of hypertension following cardiac transplantation are discussed. However, in view of the possible long-term sequelae associated with cyclosporine-induced hypertension, further studies to evaluate the long-term efficacy and safety of antihypertensive agents and finally the long-term effects of hypertension on the cardiac allograft are needed.

Function of the transplanted heart: unique physiology and therapeutic implications

Orthotopic heart transplantation has become an established treatment for selected patients with refractory heart failure. Long-term survival rates are superior to those resulting from other forms of therapy for that patient population. In addition, an improved quality of life has been reported by many patients. However, despite these encouraging results, the transplanted heart does not provide the recipient with normal cardiac function. Cardiac physiology after heart transplantation is unique. Resting hemodynamics differ significantly, acutely and chronically, from those seen in healthy subjects. In addition, neural mechanisms undergo changes as a result of surgical denervation. Afferent control mechanisms and efferent responses both are altered, leading to important clinical abnormalities. Examples include altered cardiovascular responses to exercise, altered cardiac electrophysiology, and altered responses to cardiac pharmacologic agents. An improved understanding of the changes in cardiac physiology, which occur after heart transplant, may allow the care of these patients to be optimized.

Effect of donor-recipient size mismatch on left ventricular remodeling after pediatric orthotopic heart transplantation

Left ventricular (LV) hypertrophy has been reported after orthotopic heart transplantation. This study was designed to determine the pattern of LV remodeling in the first year after pediatric orthotopic heart transplantation and to elucidate the mechanism responsible for changes in LV dimensions. Serial echocardiograms of 20 children who underwent cardiac transplantation were analyzed off-line, and the following LV parameters were measured and indexed to body surface area (BSA): short-axis diameters, posterior wall thickness, length, mass, and volume in systole and diastole. Mass/volume and short-axis diameter/length ratios and ejection fraction were calculated. In 5 patients, the donor's echocardiogram was also available for analysis. The patient's systemic blood pressure at the time of the echocardiogram, ischemic time of the donor heart, number of rejection episodes, biopsy scores, and body size of the donor and patient were recorded. Patients were assigned to 2 groups based on their donor-recipient weight ratio:group 1, < or = 1.2 (n = 9); and group 2, > 1.2 (n = 11). In group 1, LV mass index remained within normal limits throughout the study period. In group 2, mass index was significantly increased 2 weeks after transplantation (72 +/- 24 vs 133 +/- 37 g/BSA1.5, p = 0.0008). LV volume, geometry, ejection fraction, systemic blood pressure, and number of rejection episodes did not differ significantly between groups. The excess LV mass index in group 2 regressed significantly during the first year after transplantation from 133 +/- 37 to 93 +/- 17 g/BSA1.5 (p < 0.005).(ABSTRACT TRUNCATED AT 250 WORDS)

Characteristics of patients surviving more than ten years after cardiac transplantation

The clinical status and quality of life of 40 patients who lived or are still alive more than 10 years after transplantation at our institution were reviewed with the use of our transplant database, prospective patient examinations, cardiac catheterization, and exercise testing. Patient-perceived health status was determined with use of the Nottingham Health Profile and General Well Being examinations. Factors associated with longevity were determined by a Cox proportional hazards model. Twenty-six patients are alive and 14 have died. The mean age at transplant was 32.4 +/- 12 years and the current age (or age at death) is 46.1 +/- 12.8 years. Actuarial freedom from rejection was similar to that of patients surviving less than 10 years (p = 0.8), but freedom from all types of infection was less (p = 0.005). Immunosuppressive drugs include cyclosporine (11/26 patients), azathioprine (24/26), and prednisone (26/26, mean dose 12.7 mg/day). Catheterization hemodynamic data show well-preserved graft function at a mean follow-up of 11.7 +/- 3.3 years. Graft coronary artery disease prevalence is 51.0% +/- 8%. Exercise test results are as follows: duration 8.7 +/- 3.5 minutes (range 2 to 16 minutes), maximum heart rate/expected rate 77.3% +/- 11% (50% to 92%), maximum systolic blood pressure 171 +/- 23 mm Hg (140 to 208 mm Hg), and metabolic equivalents 9.2 +/- 2.3 units (5.5 to 12.9 units), or about 84% of predicted. Mean score on the General Well Being examination was 75.3 +/- 21.6 (normal). Nottingham Health Profile scores were nearly normal, except for in the 50- to 64-year-old age group in categories of mobility, pain, sleep quality, and energy level. Causes of death were coronary artery disease in 7 of 14, infection in 4 of 14, lymphoma in 1 of 14, and nonlymphoid cancer in 2 of 14. In the Cox regression, variables most associated with survival (t > 2.0, multivariate p = 0.0005) were age at transplantation (t = 3.26), preoperative duration of illness (t = 3.57), postoperative cytomegalovirus infection (t = 2.16), and ejection fraction at 12 months after operation (t = -2.62). We conclude that cardiac transplantation can provide patients with end-stage cardiac failure an acceptable general medical condition, functional status, and perceived quality of life well into the second decade after operation.

Up-regulation of beta 2-adrenergic receptors in previously transplanted, denervated nonfailing human hearts

OBJECTIVES

The purpose of this study was to examine beta-adrenergic receptor signal transduction in denervated, previously transplanted human ventricular myocardium.

BACKGROUND

In model systems, surgical denervation typically results in both presynaptic and postsynaptic supersensitivity in beta-adrenergic receptor pathways and alteration in G protein-mediated signal transduction.

METHODS

We examined beta-adrenergic receptor signal transduction in the left and right ventricles removed from nine subjects with a previous transplant and surgical denervation 25 +/- 4 months after their first transplantation. Twenty-six hearts removed from organ donors served as control hearts.

RESULTS

Total beta-adrenergic receptor density and stimulation of muscle contraction in isolated right ventricular trabeculae by the nonselective agonist isoproterenol were similar in the transplant and donor groups. Beta 1-receptor density was not different in the left ventricles of the two groups but tended to be reduced (by 29%, p = 0.09) in transplant right ventricles. By contrast, beta 2-receptor density was higher in transplant left and right ventricles relative to the respective values in donor ventricles by 33% in left ventricles and 97% in right ventricles (both p < 0.05). Isoproterenol, which in particulate fractions of human heart stimulates adenylyl cyclase primarily via beta 2-receptors, produced a greater increase in cyclic adenosine monophosphate generation in membranes prepared from transplant left ventricles and right ventricles compared with donors. In contrast, guanosine 5'-[beta,gamma-imido]triphosphate, sodium fluoride and forskolin, which stimulate adenylyl cyclase through nonreceptor/G protein-sensitive mechanisms, yielded similar degrees of adenylyl cyclase stimulation in the two groups, and both pertussis toxin- and cholera toxin-catalyzed adenosine diphosphate ribosylation were not altered in transplanted left ventricles.

CONCLUSIONS

These data indicate that the transplanted human heart exhibits an up-regulation of functional beta 2-adrenergic receptors.

The role of echocardiography in heart transplantation

Echocardiography has gained increasing importance as an imaging modality in the care of the cardiac transplant recipient. Its utility in detecting the complications of transplantation, with special reference to the diagnosis of rejection and graft arteriosclerosis, is discussed. On the basis of a review of the current literature, an outline for serial echocardiographic studies is proposed.

Hirudins: antithrombin anticoagulants

OBJECTIVE

To review the chemistry, pharmacology, available clinical data, and adverse effects of the hirudin anticoagulants.

DATA SOURCES

A MEDLINE search and a review of recent scientific abstracts was conducted to identify pertinent literature.

STUDY SELECTION

Focus was placed on studies conducted in humans. Because hirudin is still an investigational agent, however, relevant animal data, particularly pharmacokinetic studies and studies of preclinical efficacy, were also selected.

DATA EXTRACTION

Data from both human and animal studies were evaluated; emphasis was placed on human trials.

DATA SYNTHESIS

Hirudin has demonstrated potent anticoagulant effects. Although hirudin could have a significant impact on the therapeutic management of patients requiring anticoagulant therapy, only a limited number of human studies have been published to date. Trials comparing hirudin and heparin in specific patient populations are still ongoing.

CONCLUSIONS

Although still in clinical trials, hirudin is a unique agent that may represent a breakthrough in anticoagulant therapy. The specific role that this agent will play in the management of patients has yet to be determined.