Ann Thorac Surg 1995;60:1772-1777
© 1995 The Society of Thoracic Surgeons
Original Articles: Cardiovascular
Myocardial Lactate Dehydrogenase Subunit Ratio in Cardiac Allograft Recipients
Bernard Albat, MD,
Emile Missov, MD,
Anne-Marie Boularan, MD,
Marc Ferrière, MD,
Isabelle Serre, MD,
Bernard Descomps, MD,
Paul-André Chaptal, MD
Service de Chirurgie Thoracique et Cardio-Vasculaire, Hôpital Arnaud de Villeneuve, Centre Hospitalier Universitaire de Montpellier, Montpellier, France
Accepted for publication August 9, 1995.
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Abstract
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Background. Allograft coronary artery disease (CAD) is a major long-term complication in heart transplanted patients. However, the metabolic basis of allograft CAD remains to be fully elucidated. We analyzed the lactate dehydrogenase heart (H) and muscle (M) isoenzyme pattern in endomyocardial biopsy specimens and the evolution of the H/M ratio to test whether changes in this ratio could be the earliest manifestation of allograft CAD.
Methods. Twenty-four heart transplant recipients were followed up for 12 months. Endomyocardial biopsy was performed at 1, 2, 3, 6, and 12 months after transplantation. Lactate dehydrogenase 1 through 5 isoenzymes were separated by electrophoresis, and the H/M ratio was calculated. Two groups of patients were identified: group 1 (n = 20), patients without allograft CAD; and group 2 (n = 4), patients with poor outcome (three deaths, 1 case of low cardiac output) and angiographic and histologic evidence of allograft CAD.
Results. Both groups had similar H/M baseline values. The H/M ratio was higher (p = 0.01) in group 1 at 6 months (3.48 ± 0.64 versus 2.17 ± 0.43) and 12 months (3.76 ± 0.92 versus 2.18 ± 0.45) when compared with group 2. The H/M ratio increased from 2.78 ± 0.89 at 1 month to 3.76 ± 0.92 at 12 months (p = 0.02) in group 1 and decreased in group 2 (2.86 ± 0.49 versus 2.18 ± 0.45; not significant).
Conclusions. Changes in H/M ratio reflect an anaerobic shift in the lactate dehydrogenase isoenzyme composition and can be taken as an early indicator of allograft CAD.
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Introduction
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Allograft coronary artery disease (CAD) is a major obstacle to long-term survival in orthotopic heart transplant recipients [1, 2]. Although extensive clinical and experimental work has addressed the underlying morphologic and immunologic mechanisms [3–5], data are lacking concerning the myocardial metabolic state in this setting.
Vascular anatomy plays a key role in oxygen delivery to the myocytes under basal and stressed conditions. The primary cause for the transition from aerobic to anaerobic processing of glucose is the decrease in endocardial coronary perfusion [6, 7]. The diffuse obliterative process of allograft CAD induces significant adaptive metabolic changes by reducing the total cross-sectional area of the myocardial vascular bed. Cardiomyocytes are aerobically metabolizing cells that produce large amounts of adenosine triphosphate to ensure membrane integrity and to meet the energetic demand of the contractile apparatus. The diminished oxygen supply will then result in an enhanced cellular anaerobic glycolysis and, therefore, in a more inefficient energy production.
Myocardial enzyme activities have been shown to rapidly respond to different pathophysiologic conditions such as hypertrophy and dilation in congestive heart failure caused by pressure--volume overload, ethanol-induced heart muscle disease [8], and different therapeutic interventions such as angiotensin-converting enzyme [9] or anthracycline therapy [10].
Lactate dehydrogenase (LDH) is a tetrameric enzyme composed of two genetically distinct heart (H) and muscle (M) monomeres, randomly expressed in five LDH isoenzymes (LDH1 through LDH5). The expression of the H subunits in LDH is specific for aerobically metabolizing cells. They constitute 100% of the polypeptide chains in the LDH1 isoenzyme (H4), 75% in the LDH2 (H3, M1), 50% in the LDH3 (H2, M2), 25% in the LDH4 (H1, M3), and 0% (M4) in the LDH5 isoenzyme [11, 12]. Lactate dehydrogenase catalyzes the interconversion of pyruvate and lactate in close relation with the redox status of nicotinamide-adenine dinucleotide (NAD), acting as a pyruvate reductase under anaerobic conditions, and as LDH in aerobically metabolyzing cells. Lactate dehydrogenase is closely linked to the electron chain transport and the production of ATP. The prevalence of more H- or M-containing LDH isoenzymes in myocardial biopsy samples can therefore be used as a sensitive, although indirect indicator of the oxygen availability to the cells [9, 11, 12].
This prospective study was designed to investigate (1) the distribution of the LDH H and M polypeptide chains as markers of the myocardial aerobic and anaerobic glycolytic stress in endomyocardial biopsy specimens; (2) the evolution of their ratio (H/M ratio) in heart transplant patients over 1 year of follow-up; and (3) whether changes in this ratio could be predictive of poor left ventricular (LV) performance resulting from the development of severe allograft CAD.
We further tested the potential for other qualitative and quantitative variables (type of cardiomyopathy, cytomegalovirus infection, number of acute rejection episodes in the first posttransplantation year, recipients' and donors' age, total graft ischemic time) to account for modifications in the H/M ratio values. Finally, the relationships between these variables and the H/M ratio values were examined.
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Patients and Methods
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This study was performed with the approval of the institutional review board, and informed consent was obtained from all subjects. Twenty-four patients were enrolled and followed up for 12 months after transplantation. They constitute the study population.
Clinical Interventions
The immunosuppressive regimen included a 5-day perioperative course of lymphocyte antibody therapy. Azathioprine was given at a dose of 2.0 to 2.5 mg• kg-1•day-1 intravenously preoperatively, and subsequently adjusted to maintain a white blood cell count greater than 3,500 x 109/L. Methylprednisolone was given at 1.5 mg•kg-1•day-1 intraoperatively, and then tapered to the dose of 0.3 mg•kg-1•day-1, which was maintained for 3 months. Methylprednisolone was further tapered to the dose of 0.1 mg•kg-1•day-1. Cyclosporine administration was started on postoperative day 3. Cyclosporine-specific blood levels were kept between 150 and 250 ng/mL. Additional treatment with 250 mg of aspirin and 300 mg of dipyridamole was also given.
Right ventricular endomyocardial biopsies were routinely performed through the jugular vein approach under fluoroscopic guidance from the septal part of the right ventricle for histologic surveillance at 1, 2, 3, 6, and 12 months after transplantation. Cellular rejection was evaluated by conventional light microscopy according to the International Society for Heart and Lung Transplantation grading system [13] by the same experienced observer, blind to the study protocol. Each grade 3A rejection or more on endomyocardial biopsy was treated by supplemental immunosuppressive therapy. The number of times a patient received such a therapy during follow-up represents the total number of acute rejection episodes.
A fourfold increase in cytomegalovirus immunoglobulin G titers was taken as serologic evidence for both primary and secondary cytomegalovirus infection. Fractional shortening and isovolumic relaxation time, reflecting the graft systolic and diastolic function, were derived from routine two-dimensional Doppler echocardiography at the same study time end-points as adjuncts in the diagnosis of transplant-associated atherosclerosis. Coronary arteriography was performed at the end of the follow-up period. The arteriograms were analyzed by two independent observers familiar with the findings of allograft CAD in heart transplant recipients.
Lactate Dehydrogenase Isoenzyme Quantification
Right ventricular specimens for biochemical analysis were immediately frozen in liquid nitrogen and stored at -80°C until assay. Myocardial biopsy samples weighing 0.2 to 0.5 mg were mixed with Tris buffer, pH 7.2, in a polypropylene microtube and further crushed with an electric mixer blender provided with a Teflon pestle. After subsequent centrifugation at 3,000 g, an aliquot of each supernatant (5 µL) was directly applied on each slit membrane for electrophoretic separation, and another aliquot was further diluted with an equal volume of Tris buffer for biochemical determination. Total LDH activity was performed on a Kodak Ektachem 700 analyzer (Eastman Kodak Co, Rochester, NY) using a dry, multilayered analytic slide containing pyruvate and reduced NAD as substrates. Reduced NAD oxidation was monitored by measuring reflection density changes at 340 nm, and then converted to enzyme activity in international units per liter. Total protein was assayed by the SDS modified Coomassie brillant blue G250 method (Bio-Rad Laboratories, Anaheim, CA). Assay was automated on a Cobas Bio centrifugal analyzer (Roche Diagnostica, Neuilly-Sur-Seine, France). Special settings allowed an improved accuracy of protein quantification in supernatants. Enzyme activity was expressed as international units per gram of tissue proteins. Separation and quantification of the LDH isoenzymes (LDH1 through LDH5) was performed according to their charge-related electrophoretic migration under basic conditions (Tris barbital buffer, pH 9.6) on agarose membranes (Sebia, Issy-les-Moulineaux, France). The LDH activity of each separated fraction was evidenced by incubation with the specific substrate and an excess of oxidized coenzyme (lactate and NAD) under appropriate conditions (pH 10.0, 30 minutes at 50°C). The produced amounts of reduced NAD were then revealed by reduction of the nitroblue tetrazolium salt to a colored formazan blue complex, scanned densitometrically at 580 nm on a Cellosystem II densitometer (Sebia).
Statistical Analysis
All statistical analysis was performed with the SAS version 6.08 statistical package (SAS Institute Inc, Cary, NC). Analysis of variance for repeated measures was used to test between- and within-group differences. Nonparametric Mann-Whitney and Wilcoxon tests followed by Bonferroni correction were used when appropriate to compare significant points delineated by analysis of variance. Correlation analysis between variables was performed by 
2 test, Fisher's exact test, and Spearman correlation. All presented data are mean ± standard deviation. The null hypothesis was rejected for p values less than 0.05.
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Results
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Three patients died of severe allograft CAD at the end of the follow-up period. Signs of diffuse obliterative disease were found in all 3 of them at autopsy. In a fourth patient, low cardiac output developed that was refractory to maximal medical therapy. The patients were then divided into two distinct groups: group 1 (n = 20), event-free patients with preserved LV function and no evidence of allograft CAD at coronary arteriography, and group 2 (n = 4), patients with unfavorable clinical outcome and poor LV performance related to allograft CAD.
Qualitative data for patients are summarized in Table 1
. Referral for heart transplantation because of idiopathic dilated cardiomyopathy or end-stage CAD did not influence the occurence of allograft CAD, nor did the cytomegalovirus status (p = 0.5).
Quantitative data for recipients' and donors' age, graft ischemic time, and total number of acute rejection episodes are presented in Table 2. Recipients' age ranged from 15 to 64 years with a mean of 49 years in group 1, and from 44 to 55 years with a mean of 47 years in group 2. Donors' ages were similar in both groups, ranging from 15 to 48 years (mean, 28 years) in group 1 and from 19 to 49 years (mean, 30 years) in group 2. Graft ischemic intervals did not differ, ranging from 105 to 303 minutes (mean, 164.90 minutes) in group 1 and from 140 to 215 minutes (mean, 170.00 minutes) in group 2. The latter patients were more prone to experience acute rejection than were patients in group 1 (2.00 ± 0.82 versus 0.45 ± 0.82 events; p = 0.005). Furthermore, patients with idiopathic dilated cardiomyopathy were found to have somewhat higher acute rejection rates than patients with end-stage CAD (p = 0.05) in our study (data not shown).
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Table 2. . Patient Distribution by Recipients' and Donors' Age, Graft Ischemic Time, and Number of Acute Rejectionsa
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Data for the H/M ratio are summarized in Table 3. A shift in LDH subunits distribution toward the more aerobic H monomeres was evidenced by the higher H/M ratio values in group 1 at 6 months (3.48 ± 0.64 versus 2.17 ± 0.43; p = 0.01) and 12 months of follow-up (3.76 ± 0.92 versus 2.18 ± 0.45; p = 0.01), respectively (Fig 1). Starting from similar baseline levels, H/M ratios increased during the study period in group 1, the initial 1-month value being lower than the final one at 12 months (2.78 ± 0.89 versus 3.76 ± 0.92; p = 0.02). In contrast, group 2 ratios decreased over the follow-up period but did not achieve statistical significance despite a clear trend toward lower final values. Densitometric LDH scans from a typical group 1 and group 2 patient are depicted in Figure 2.
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Fig 1. . Divergent lactate dehydrogenase heart and muscle (H/M) subunit ratio kinetics in event-free patients (group 1, n = 20) without allograft coronary artery disease and in patients in whom allograft coronary artery disease developed during follow-up (group 2, n = 4) (p = 0.01 for group 1 versus group 2; p = 0.02 for group 1, 1 month versus 12 months).
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Fig 2. . (A) A typical group 1 normal densitometric scanning. From right to left, note the strong expression of lactate dehydrogenase (LDH) isoenzyme 1 (1,258 IU/g) and the very weak expression of LDH5 (309 IU/g), resulting in a high heart to muscle subunit ratio. (B) A typical group 2 densitometric scanning. From right to left, note the weak expression of LDH isoenzyme 1 (120 IU/g) and the strong expression of LDH5 (482 IU/g), resulting in a low heart to muscle subunit ratio value. (See the Material and Methods section for details on enzyme quantification.)
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The graft systolic function, evaluated by echocardiographic fractional shortening (see Table 3
), was 0.42 ± 0.07 in group 1 and significantly lower (0.24 ± 0.06; p = 0.01) in group 2 at 12 months of follow-up. Echocardiographic assessment of the diastolic function failed to document any important modification in the isovolumic relaxation time parameters (see Table 3), and no significant between- and within-group differences were found at the different study time points.
A negative correlation was found between the 12-month H/M ratio value for all patients (n = 24, data not shown) and the total number of acute rejection episodes (r = -0.54; p = 0.02): the higher the number of acute rejection episodes, the lower the H/M ratio values (Fig 3). No other statistically significant relationships were found between the graft ischemic time, the echocardiographic parameters, and the LDH subunit ratios.
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Fig 3. . Negative linear correlation between the lactate dehydrogenase heart and muscle (H/M) subunit ratio values at 12 months of follow-up for all patients (n = 24) and the number of acute rejection episodes.
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Comment
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Allograft CAD is characterized by (1) distal loss of subendocardial vessels, (2) diffuse or local luminal narrowing of the epicardial vessels, (3) LV wall motion abnormalities [14, 15], and (4) clinical signs of allograft dysfunction [16]. The resultant chronic myocardial ischemia and significant ventricular enlargement further contribute to the alteration of the systolic and diastolic properties of the myocardium [17]. Unfortunately, methods for early detection of allograft CAD are still lacking. Data from biopsy specimens, Doppler echocardiography, and coronary arteriography are often conclusive only when vascular rejection becomes clinically relevant [18].
Both the mechanical and electrical activity of the heart are energy consuming. They need efficient energy production and constantly elevated adenosine triphosphate/adenosine diphosphate ratios. Carbohydrates, free fatty acids, and proteins are then catabolized in the presence of molecular oxygen and, through acetyl coenzyme A, rejoin the citrate cycle. The close relationships between the multienzymatic steps of oxidative phosphorylation and the NAD oxidation-reduction state allows the production of large amounts of adenosine triphosphate. The cellular metabolism becomes anaerobic when the oxygen supply/demand ratio becomes extremly low. Lactate is then produced from pyruvate with a low energetic output from the subsequent anaerobic glycolytic pathway. As the enzymatic activity of LDH is closely linked to the cellular energy producing steps, it could be used for indirect estimation of the oxygen availability to the cells from endomyocardial biopsy samples.
The most important finding in our study is the potential for adaptive metabolic changes and differential myocardial LDH isoenzyme composition in response to cellular oxygen supply deficit in cardiac allograft recipients. The similar low baseline H/M values in both groups in the early postoperative period (see Table 3, Fig 1) indicate that ischemic and surgical stress at transplantation have resulted in enhanced anaerobic glycolysis, and do not support the hypothesis that more important peritransplantation myocardial injury occurred in those patients in whom allograft CAD subsequently developed [19]. It is of note that these values were lower than H/M ratios obtained in 15 patients with normal left ventricular ejection fraction undergoing diagnostic cardiac catheterization and biopsy procedures [10]. The shift toward the more aerobic LDH isoenzymes in group 1 patients clearly resulted in higher H/M ratio values at the end of the follow-up period. All these patients had a benign outcome without evidence of allograft CAD at coronary arteriography. In contrast, H/M ratio values decreased in group 2 during follow-up, indicating more profound impairment of the cellular energy-producing system. The shift toward more M-containing LDH isoenzymes resulted in more inefficient energy production through the anaerobic glycolytic pathway. Irreversible graft failure developed in 3 of these 4 patients, with histologic signs of severely diseased coronary arteries at autopsy (Fig 4). The fourth patient was considered for retransplantation because of severely compromised hemodynamic status.
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Fig 4. . Histologic findings in a typical group 2 autopsied patient: luminal narrowing of a coronary artery by severe intimal thickening. (Hematoxylin and eosin stain; x 250 before 45% reduction.)
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Another finding of this study is that multiple acute rejection episodes appear to contribute to the long-term impairment of the mitochondrial oxidative phosphorylation. Recently, it has been shown that the acute rejection process of the orthotopically transplanted heart is accompanied by significant alterations in the myocardial energy content [20]. This is further supported by the higher acute rejection rate in group 2 patients in our study and by the significant correlation between the LDH subunit ratio values and the number of acute rejection episodes in the whole study population (see Fig 3). The allograft CAD-induced impairment in myocardial energy production appears then to be much more difficult to correct than the classic metabolic imbalance seen in congestive heart failure irrespective of its cause. An angiotensin-converting enzyme inhibitor, enalapril, has been found to modify the LDH composition in idiopathic dilated cardiomyopathy, increasing the LDH1 and decreasing the LDH5 fractions, thus indicating a significant improvement of the myocardial energetic balance [9]. More aggressive therapeutic interventions are probably needed to counteract the energetic defficiency in the transplanted human heart. Achievement of precise therapeutic goals could be monitored by the LDH isoenzyme pattern, based on the association of low H/M ratio values, accelerated arteriosclerosis, and multiple acute rejection episodes. Furthermore, this ratio has already been of proven value in the therapeutic management and surveillance of patients receiving the theoretic maximal dose of anthracyclines, adding quantitative biochemical information to the histologic study of the endomyocardial biopsy samples [10].
Our study provides clear evidence that irreversible graft failure in allograft CAD is the consequence, at least in part, of an energy-depleted state secondary to inhibited oxydative metabolism, and that myocardial enzymatic activities respond to environmental changes in oxygen availability. These alterations become apparent in the third posttransplantation month (see Fig 1) and reach statistical significance at 6 months after transplantation, when the left ventricular fractional shortening is still within the normal range and LV failure is not clinically suspected. The serial echocardiographic findings in our study were not correlated with the LDH isoenzyme pattern and did not allow early noninvasive diagnosis of graft failure secondary to allograft CAD. The fractional shortening was significantly reduced in group 2 patients late in the follow-up, when there was already biochemical, angiographic, and clinical evidence of graft failure. Echocardiographically detectable LV dysfunction thus appears to be of limited value in the prediction and early diagnosis of transplant arteriosclerosis [21].
Although our findings add biochemical information about the evolution of the myocardial metabolism in event-free patients and in patients with allograft CAD, there are several limitations to the present study. The patient numbers are small, especially when group 2 is considered, possibly leading to underestimation of some results whose clinical and biological significance seems otherwise justified. For example, we failed to document any relationship between the cytomegalovirus serology and the subsequent development of allograft CAD, although cytomegalovirus infection has been associated with more severe disease in other studies and identified as a potent risk factor [22]. No conclusive data were obtained concerning the potential causality between numerous predisposing factors (cause of disease, graft ischemic time, donors' and recipients' age) and the subsequent development of allograft CAD. Frequently, such an association found in some studies has not been confirmed in others. Furthermore, the reported H/M ratio values probably do not reflect a global myocardial metabolic state, but rather a subendocardial one, because of the biopsy technique and the possible longitudinal, radial, and transseptal heterogeneity in the distribution of both the aerobic and anaerobic glycolytic stress [23]. Finally, newer diagnostic technologies, such as intracoronary ultrasound or intravascular angioscopy, might provide more precise information than conventional coronary arteriography in allograft CAD follow-up, but they were not used in our study population.
In conclusion, our study shows that in cardiac allograft recipients, the myocardial LDH enzymatic substrate differs significantly in event-free patients and in patients with poor clinical outcome related to allograft CAD. It highlights the key role of the aerobic oxidative metabolism in energy production, and provides clear evidence for divergent H/M ratio kinetics in patients with and without allograft CAD. We conclude that monitoring of H/M ratios in biopsy samples is of clinical interest for graft surveillance, and that it could be a simple, readily available, and useful tool for early detection of patients at high risk for severe allograft CAD.
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Acknowledgments
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We are grateful to Marie-Christine Picot for her expert statistical advice.
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Footnotes
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Presented in part at the Twenty-ninth Congress of the European Society for Surgical Research, Montpellier, France, May 16--19, 1994.
Address reprint requests to Dr Albat, Service de Chirurgie Thoracique et Cardio-Vasculaire, Hôpital Arnaud de Villeneuve, CHU de Montpellier, 34295 Montpellier Cedex 05, France.
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References
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|---|
- Johnson DE, Gao SZ, Schroeder JS, DeCampli WM, Billingham ME. The spectrum of coronary artery pathologic findings in human cardiac allografts. J Heart Lung Transplant 1989;8:349–59.
- Miller LW, Wesp A, Jennison SH, et al. Vascular rejection in heart transplant recipients. J Heart Lung Transplant 1993;12:S147–52.[Medline]
- Paanoven T, Mennander A, Lautenschlager I, Mattila S, Häyry P. Endothelialitis and accelerated arteriosclerosis in human heart transplant coronaries. J Heart Lung Transplant 1993;12:117–22.[Medline]
- Utans U, Liang P, Wyner LR, Karnovsky MJ, Russel ME. Chronic cardiac rejection: identification of five upregulated genes in transplanted hearts by differential mRNA display. Proc Natl Acad Sci 1994;91:6463–7.[Abstract/Free Full Text]
- Crisp SJ, Dunn MJ, Rose ML, Barbir M, Yacoub MH. Antiendothelial antibodies after heart transplantation: the accelerating factor in transplant-associated coronary artery disease? J Heart Lung Transplant 1994;13:81–92.[Medline]
- Vatner S. Reduced subendocardial myocardial perfusion as one mechanism for congestive heart failure. Am J Cardiol 1988;62:94E--8E.[Medline]
- Vatner S, Hittinger L. Coronary vascular mechanisms involved in decompensation from hypertrophy to heart failure. J Am Coll Cardiol 1993;22:34A--40A.[Medline]
- Preedy VR, Richardson PJ. Ethanol induced cardiovascular disease. Br Med Bull 1994;50:152–63.[Abstract/Free Full Text]
- Schultheiss HP. Effect on the myocardial energy metabolism of angiotensin-converting enzyme inhibition in chronic heart failure. Am J Cardiol 1990;65:74G--81G.[Medline]
- Ferrière M, Donnadio D, Michel F, Descomps B, Latour H. La biopsie endomyocardique dans la surveillance des traitements par anthracyclines. Intérêt du dosage de la lacticodéshydrogénase et de ses isoenzymes. Ann Cardiol Angéiol 1986;35:75–9.
- Ferrière M, Michel F, Messner P, et al. Répartition des isoenzymes de la lacticodéshydrogénase du myocarde humain obtenu à partir de biopsies endomyocardiques. Ann Cardiol Angéiol 1985;34:61–4.
- Schulteiss HP, Bolte HD, Cyran J. Lactate dehydrogenase isoenzyme pattern in myocardial biopsies of patients with congestive cardiomyopathy and with alcoholic cardiomyopathy: clinical and experimental results. In: Bolte HD, ed. Myocardial biopsy. Berlin: Springer Verlag, 1980:105--15.
- Billingham ME, Cary NRB, Hammond ME, et al. A working formulation for the standardization of nomenclature in the diagnosis of heart and lung rejection: Heart Rejection Study Group. J Heart Lung Transplant 1990;9:587–93.
- Valantine HA. Rejection surveillance by doppler echocardiography. J Heart Lung Transplant 1993;12:422–6.[Medline]
- St. Goar FG, Gibbons R, Schnittger I, Valantine HA, Popp L. Left ventricular diastolic function: Doppler echocardiographic changes soon after cardiac transplantation. Circulation 1990;82:872–8.[Abstract/Free Full Text]
- Johnson DE, Gao SZ, Schroeder JS, DeCampli WM, Billingham ME. The spectrum of coronary artery pathologic findings in human cardiac allografts. J Heart Lung Transplant 1989;8:349–59.
- Mullins PA, Cary NR, Sharples L, et al. Coronary occlusive disease and late graft failure after cardiac transplantation. Br Heart J 1992;68:260–5.[Abstract/Free Full Text]
- Everett JP, Hershberger RE, Ratkovec RM, et al. The specificity of normal qualitative angiography in excluding cardiac allograft vasculopathy. J Heart Lung Transplant 1994;13:142–9.[Medline]
- Gaudin PB, Rayburn BK, Hutchins GM, et al. Peritransplant injury to the myocardium associated with the development of accelerated arteriosclerosis in heart transplant recipients. Am J Surg Pathol 1994;18:338–46.[Medline]
- Benvenuti C, Aptecar E, Deleuze P, et al. Myocardial high-energy phosphate depletion in allograft rejection after orthotopic human heart transplantation. J Heart Lung Transplant 1994;13:857–61.[Medline]
- Picard MH. Echocardiography in cardiac transplantation. In: Weyman AE, ed. Principles and practice of echocardiography, 2nd ed. Philadelphia: Lea & Febiger, 1994:1231--39.
- Koskinen PK, Nieminen MS, Krogerus LA, et al. Cytomegalovirus infection and accelerated cardiac allograft vasculopathy in human cardiac allografts. J Heart Lung Transplant 1993;12:724–9.[Medline]
- Sylven C, Lin L, Kallner A, Jansson E. Regional distribution of citrate synthase and lactate dehydrogenase isoenzymes in the bovine heart. Acta Physiol Scand 1989;136:331–7.[Medline]
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Abstract
Introduction
