Noninvasive discrimination of rejection in cardiac allograft recipients using gene expression profiling

Rejection diagnosis by endomyocardial biopsy (EMB) is invasive, expensive and variable. We investigated gene expression profiling of peripheral blood mononuclear cells (PBMC) to discriminate ISHLT grade 0 rejection (quiescence) from moderate/severe rejection (ISHLT > or = 3A). Patients were followed prospectively with blood sampling at post-transplant visits. Biopsies were graded by ISHLT criteria locally and by three independent pathologists blinded to clinical data. Known alloimmune pathways and leukocyte microarrays identified 252 candidate genes for which real-time PCR assays were developed. An 11 gene real-time PCR test was derived from a training set (n = 145 samples, 107 patients) using linear discriminant analysis (LDA), converted into a score (0-40), and validated prospectively in an independent set (n = 63 samples, 63 patients). The test distinguished biopsy-defined moderate/severe rejection from quiescence (p = 0.0018) in the validation set, and had agreement of 84% (95% CI 66% C94%) with grade ISHLT > or = 3A rejection. Patients >1 year post-transplant with scores below 30 (approximately 68% of the study population) are very unlikely to have grade > or = 3A rejection (NPV = 99.6%). Gene expression testing can detect absence of moderate/severe rejection, thus avoiding biopsy in certain clinical settings. Additional clinical experience is needed to establish the role of molecular testing for clinical event prediction and immunosuppression management.

Prevention of cardiac allograft rejection by FK506 and rapamycin: assessment by histology and nuclear magnetic resonance

We assessed the effect of FK506 and rapamycin (RPM) in a heterotopic abdominal rat heart transplant model using a major histocompatibility mismatch (DA to LEW). The end-point of our study was the histologic grading of rejection (Stanford) and 31P magnetic resonance spectroscopy (MRS) at 1 week after transplantation. Two dosages of FK506 (2.0 and 8.0 mg/kg per os daily) and RPM (1.5 and 6.0 mg/kg intraperitoneally daily) were compared in allografts without and with cyclosporine (12.5 mg/kg per os daily) treatment. The results show: Weak heartbeat and full rejection at day 5 in all untreated allografts; severe rejection in groups on a low dose of FK506 and RPM; mild rejection in both high dose groups comparable to the results of the hearts treated with cyclosporine; MRS does not allow differentiation between no or mild forms of rejection. Energy-rich phosphates are near normal in the high dosage immunosuppression groups but show a significant reduction in the low dosage groups. We conclude that all three tested drugs can reduce the degree of rejection from severe (untreated allografts) to mild if given in an adequate dosage. MRS correlates well with the degree of histologic rejection but permits only the diagnosis of moderate or severe rejection.

Differential expression pattern of membrane-type matrix metalloproteinases in rheumatoid arthritis

OBJECTIVE

To study the expression of messenger RNA (mRNA) for different membrane-type matrix metalloproteinases (MT-MMPs) and compare their expression pattern in rheumatoid arthritis (RA) and normal synovium.

METHODS

Polymerase chain reaction (PCR) with specific primers was performed to analyze the presence of MT1-, MT2-, MT3-, and MT4-MMP in synovial tissue and synovial fibroblasts from 10 patients with RA and 4 subjects without arthritis. In addition, in situ hybridization with digoxigenin-labeled RNA probes was used to investigate the expression pattern of MT-MMPs in the synovium of these subjects. MT-MMP-expressing cells were characterized by immunohistochemical double labeling with anti-CD68 monoclonal antibodies.

RESULTS

Reverse transcription-PCR revealed the expression of MT1-, MT2-, MT3-, and MT4-MMP mRNA in all tissues and cell cultures examined. However, in situ hybridization showed considerable differences in the expression pattern of the different MT-MMPs in RA synovium. MT1- and MT3-MMP mRNA were highly expressed in both the lining and the sublining layer, with more intense staining in the lining. Immunohistochemical double labeling demonstrated the presence of mRNA for MT1-MMP in fibroblasts and macrophages, as well as in osteoclast-like cells at sites of bone resorption. Expression of MT3-MMP mRNA was seen in fibroblasts and some macrophages. Expression of MT2- and MT4-MMP was characterized by staining of only a few CD68-negative fibroblasts, and no differences could be found between the lining and sublining. Normal synovial samples showed only limited staining for all MT-MMPs.

CONCLUSION

Our results indicate a role for MT1-MMP not only in the matrix degradation by fibroblasts, but also in osteoclast-mediated bone resorption in RA. Given the ability of MT1-MMP to activate MMP-2 and MMP-13, the findings also point to a cooperation between fibroblasts and macrophages in degrading cartilage and bone. While MT3-MMP is also intensely expressed in RA synovium, MT2- and MT4-MMP appear not to be involved in rheumatoid joint destruction.

Rapamycin reverses chronic graft vascular disease in a novel cardiac allograft model

BACKGROUND

Chronic graft vascular disease (CGVD) in cardiac allografts has been defined as a slowly evolving vasculopathy unresponsive to conventional immunosuppression. We compared 4 rodent models of CGVD to evaluate the reproducibility of CGVD in heart allografts. Rapamycin (Rapa) and cyclosporine (CSA) were then used to treat CGVD.

METHODS AND RESULTS

Hearts were harvested and placed heterotopically into allogenic recipients. CGVD scores of PVG allografts from ACI recipients treated with CSA on days 1 through 10 were significantly elevated on day 90 (n=16) compared with other models (immunosuppression used): (1) Lewis to F344 recipients (CSA), (2) Brown Norway to Lewis (FK506), and (3) DA to Wistar-Firth (methylprednisolone, azathioprine, CSA). Although delayed (day 60 to 90) CSA treatment had no effect (n=6), delayed Rapa (3 mg. kg-1. d-1 IP) reversed CGVD in PVG grafts (0.22+/-0.19 on day 90, n=6). ACI isografts showed no evidence of CGVD (n=6) at day 90. Immunohistochemistry of PVG grafts revealed perivascular infiltrates consisting of CD4(+) T cells and limited numbers of macrophages persisting up to day 90. Flow cytometry demonstrated increased levels of anti-donor antibody at day 90, which was significantly inhibited by Rapa treatment.

CONCLUSIONS

PVG grafts developed a significant increase in CGVD without evidence of ongoing myocardial rejection. This CGVD appeared to be mediated by both cellular and humoral mechanisms, given CD4(+) perivascular infiltrates and increased levels of anti-donor antibody. The anti-CGVD effectiveness of Rapa during a period in which there was little myocardial cellular infiltrate supports a novel mechanism of effect such as smooth muscle or B-cell inhibition.

Membrane-type-1 matrix metalloproteinase is abundantly expressed in fibroblasts and osteoclasts at the bone-implant interface of aseptically loosened joint arthroplasties in situ

OBJECTIVE

To investigate the distribution pattern of membrane-type-1 matrix metalloproteinase (MT1-MMP) within the synovial-like interface membranes of failed prosthetic joints.

METHODS

Interface tissue around loose arthroplasties containing both fibrous membrane and attached bone was obtained from 6 patients at revision surgery. In situ hybridization with digoxigenin labeled RNA probes was applied to investigate MT1-MMP expression in paraffin sections of the samples. In addition, double labeling using immunohistochemistry was performed to characterize MT1-MMP producing cells.

RESULTS

Apart from being present in fibroblasts, MT1-MMP was also found expressed in osteoclasts at sites of bone resorption. Our results revealed no expression of MT1-MMP at parts of the membrane that originally had been located next to the prosthesis. In contrast, abundant staining for MT1-MMP was observed at sites attached to bone. MT1-MMP mRNA expression was more intense at those sites of bone resorption covered by a thicker interface membrane.

CONCLUSION

These results indicate a role for MT1-MMP not only in matrix degradation by fibroblasts but also in osteoclast mediated bone resorption. Given the ability of MT1-MMP to activate MMP2 and MMP13, they suggest also that osteoclasts might contribute to matrix degradation by activating these MMP. This could be of potential interest not only for other conditions in which bone resorption by fibroproliferative tissue plays a role, but also to design novel strategies to prevent loosening of prosthetic joints.

The use of cardiac biopsy to demonstrate reduced cardiotoxicity in AIDS Kaposi's sarcoma patients treated with pegylated liposomal doxorubicin

BACKGROUND

Pegylated liposomal doxorubicin (PL-DOX) has been shown in preclinical models to induce less cardiotoxicity than non-liposomal doxorubicin. Endomyocardial biopsy is a highly sensitive and specific method for detecting anthracycline-induced cardiac damage.

PATIENTS AND METHODS

Myocardial tissue from ten KS patients who had received cumulative PL-DOX (20 mg/m2/biweekly) of 440-840 mg/m2 was evaluated for evidence of anthracycline-induced cardiac damage. Controls were assembled from patients who had received cumulative doxorubicin doses of 174-671 mg/m2 in two earlier cardiac biopsy protocols. Two control groups were selected on the basis of both cumulative (+/- 10 mg/m2) and peak doxorubicin dose (60 or 20 mg/m2, control group 1), or peak dose alone (20 mg/m2, control group 2).

RESULTS

PL-DOX patients had significantly lower biopsy scores compared with those of doxorubicin controls despite higher cumulative doses of anthracycline. The median biopsy scores for the PL-DOX and doxorubicin groups, respectively, were 0.3 vs. 3.0 (P = 0.002, Cochran-Mantel-Haenszel row mean difference test) for group 1 and 1.25 for group 2 (P < 0.001, Wilcoxon rank-sum test).

CONCLUSIONS

Less severe cardiac changes were seen in patients given PL-DOX relative to historical control patients given comparable cumulative doses of doxorubicin.

Diabetes and dyslipidemia. A new model for transplant coronary artery disease

BACKGROUND

Clinical observations suggest that transplant coronary artery disease (TxCAD) is immunologically mediated but may be accelerated by metabolic derangements. We developed a rat model of heterotopic heart transplantation in the presence of diabetes and dyslipidemia to further study their role in TxCAD development.

METHODS AND RESULTS

Major histocompatibility complex-mismatched strains of inbred rats underwent heterotopic heart transplantation (ACI-to-Lewis allografts). Diabetes (DM) was induced by streptozotocin injection (80 mg/kg) after transplantation; dyslipidemia was worsened by feeding of a 60% high-fructose diet (+F). Allograft transplants were divided into four groups: (1) +DM/+F; (2) +DM/-F; (3) -DM/+F; and (4) -DM/-F. Isograft transplants (Lewis to Lewis, +DM/+/-F) were controls. All animals received daily cyclosporine (5 mg/kg). Grafts surviving > 30 days were evaluated for TxCAD on histological sections and graded 0 to 5 for intimal thickness. All streptozotocin-treated animals were diabetic within 2 weeks, with fourfold increases in plasma glucose concentrations versus nondiabetics. Severe TxCAD was observed in diabetic allografts only. The mean grade of TxCAD in diabetic allografts was 3.2 +/- 0.5 versus 1.1 +/- 0.4 in diabetic isografts (P < 0.03) and zero TxCAD in nondiabetic allografts (P < or = 0.0001). Fructose feeding resulted in a 1.5-fold higher triglyceride and a 1.3-fold higher cholesterol level versus the regular diet (-F) but showed no independent contribution to the development of TxCAD.

CONCLUSIONS

These findings suggest that metabolic derangements associated with diabetes play an important role in TxCAD development in heterotopic ACI-to-Lewis rat heart transplantation. In this model of TxCAD in major histocompatibility complex-mismatched, diabetic, and dyslipidemic rats, immunologic and metabolic mechanisms that contribute to TxCAD can be further delineated and approaches to its prevention assessed.

Intracoronary arterial occlusion: a novel technique potentially useful for ablation of cardiac arrhythmias

To develop a new technique for ablating arrhythmias by interrupting coronary perfusion of the myocardium, we studied six mongrel dogs, weighing 20-35 kg. Under angiographic guidance a microcatheter (1.0 mm diameter) was introduced into a branch of the left anterior descending or posterior descending coronary artery. A detachable platinum coil (0.0254 cm diameter, 3 cm length) soldered onto a stainless-steel delivery wire (Guglielmi) was inserted through the microcatheter and advanced to occlude the arterial branch. A 0.5-mA electric current applied to the proximal end of the delivery wire resulted in intravascular thrombosis due to attraction of the negatively charged blood cells, platelets, and fibrinogen to the positively charged platinum coil. In approximately 4.5 minutes, as the thrombus was formed, electric current dissolved the soldering and detached the platinum coil from the delivery wire. Electrocardiograms showed focal ST-T changes but no ventricular tachyarrhythmias. Pathologic studies revealed thrombosis around the platinum coil and well-demarcated focal ischemia/infarction that was correlated with elevation of cardiac enzymes. We conclude that intracoronary arterial embolization and electrothrombosis using an electrolytic platinum coil can be selectively performed in a very small coronary arterial branch, resulting in a limited area of myocardial damage. This technique is potentially useful for ablating arrhythmias and may be safer and more controllable than intracoronary alcohol infusion.

Phase I results of pullback atherectomy for hemodialysis access

PURPOSE

Balloon angioplasty and directional atherectomy frequently have short-lived results for stenoses associated with hemodialysis. Results are reported for a phase I trial of the pullback atherectomy catheter (PAC) for treatment of hemodialysis access-related stenoses.

PATIENTS AND METHODS

Six intragraft and six venous stenoses in nine patients were treated with the PAC. Two lesions were treated with adjunctive balloon angioplasty, and two were treated with adjunctive directional atherectomy. Clinical and angiographic follow-up were obtained for all patients. All specimens were examined histologically.

RESULTS

Initial procedural success was achieved in 83% of stenoses (10 of 12). For intragraft stenoses, the 6-month primary patency was 60% (three of five) and the 6-month secondary patency was 80% (four of five). All six venous stenoses restenosed or thrombosed within 3 months. All specimens contained fibrous plaque or intimal hyperplasia. In addition, all six venous stenosis specimens contained media and two contained adventitia. Significant complications during treatment of venous stenoses included severe venous spasm in three and venous pseudoaneurysms in two. One PAC tip fracture occurred during treatment of an intragraft stenosis.

CONCLUSION

Pullback atherectomy is potentially safe and effective for intragraft stenoses; however, it is not safe or effective for venous stenoses.

A working formulation for the standardization of nomenclature and for clinical staging of chronic dysfunction in lung allografts. International Society for Heart and Lung Transplantation

A clinically applicable, standardized method for assessing functional results after lung transplantation is required to evaluate factors that may affect long-term outcome, to permit comparison of results from different centers, and to evaluate results of clinical trials. An ad hoc working group was established under the auspices of the International Society for Heart and Lung Transplantation for the purpose of developing such a clinically applicable system. Chronic allograft dysfunction is often associated with pathologic findings of obliterative bronchiolitis, the cause of which has not been defined. Physiologically, such dysfunction is associated with obstructive airways disease. The group concluded that the forced expiratory volume in 1 second was the most reliable and consistent indicator of graft dysfunction, excluding other identifiable causes. The term bronchiolitis obliterans syndrome was adopted to describe such dysfunction, recognizing that there may or may not be pathologic evidence of bronchiolitis obliterans present. Four stages of bronchiolitis obliterans syndrome were defined, each with two subcategories to indicate whether pathologic evidence of obliterative bronchiolitis had been identified. This working formulation will require reappraisal in the future to reassess its practical application and to make such adjustments as may seem appropriate.

Time course and cellular characteristics of the iliac artery response to acute balloon injury. An angiographic, morphometric, and immunocytochemical analysis in the cholesterol-fed New Zealand white rabbit

Evaluation of the response of the arterial vessel wall to acute arterial injury in experimental models has taken on substantial importance because of an increasing interest in angioplasty treatment of human atherosclerotic lesions. In this study, the response of normal arterial vessels to acute balloon injury was studied in 45 iliac artery segments from 24 New Zealand White rabbits fed a 2% cholesterol diet. At specified time points between 1 and 41 days after the initial balloon pullback injury, the iliac arteries were analyzed by angiographic, morphometric, and immunocytochemical techniques. Angiographic measurements indicated progressive compromise of the iliac artery lumen with increasing duration of time from injury. Morphometric measurements showed that intimal area increased from 0.004 +/- 0.01 mm2 3 days after injury to 1.15 +/- 0.30 mm2 34-41 days after injury. Cell line-specific immunocytochemical analysis identified the macrophage as a prominent component of the earliest intimal cellular infiltrate. Smooth muscle cells appeared within the intima 7-9 days after injury. As the intima increased in area, macrophages predominated along the internal elastic lamina aspect of the intimal lesion while smooth muscle cells occupied the portion of the intima adjacent to the lumen. In summary, retrograde balloon pullback injury followed by cholesterol feeding results in progressive arterial luminal narrowing due to a progressively enlarging intimal cellular infiltrate. The temporal and spatial contributions of smooth muscle cell and macrophage components of the developing intimal cellular infiltrate have been characterized.

The conduction system in transplanted hearts

This is a serial section examination of the conduction system (CS) in six patients who died seven months, 11 months, two years four months, four years two months, 11 years, and 16 years eight months following cardiac transplantation. The heart was hypertrophied and enlarged in all. There was myocarditis of varying degree in all cases with arteriosclerosis and arteriolosclerosis. These findings were more dominant in the atria than in the ventricles. In the CS, myocarditis with fibrosis was found in all in the approaches to the sinoatrial (SA) node, the SA node, the atria, the atrioventricular (AV) node, and the bundle and bundle branches, to a varying degree. When compared with the endomyocardial biopsy findings, the autopsied cases revealed more myocarditis and fibrosis than those estimated to be present in the biopsy specimen. In summary, this study demonstrates that there are fibrotic changes in the CS with the persistence of inflammatory phenomena of the myocardium and the CS to a varying degree in transplanted hearts. This is accompanied by the ubiquitous coronary artery disease affecting not only the large coronaries but also the small vessels. The pathologic changes in and around the CS may be responsible for arrhythmias and sudden death in some cases of cardiac transplantation.

Cardiac growth after pediatric heart transplantation

BACKGROUND

To assess whether normal cardiac growth occurs after heart transplantation in the pediatric age group, we performed a study of 13 infants and children who underwent orthotopic heart transplantation at Stanford.

METHODS AND RESULTS

The echocardiographic data from a population of 93 normal children were analyzed to determine estimates of the fifth, 25th, 50th, 75th, and 95th percentiles of the normal pediatric population. Growth curves for each of the cardiac dimensions were stratified into six classes representing each of the percentile bands, and dimensions for the 13 patients were tracked between early postoperative (early) and point of maximal follow-up (late). Results were compared by Student's paired t test to determine whether normal growth was occurring. The mean age at transplant was 5.0 +/- 1.3 years (mean +/- SEM) (range, 0.4-12.8 years), duration of follow-up was 3.1 +/- 0.4 years (1.3-5.8 years), and change in body surface area was 0.24 +/- 0.03 m2 (0.12-0.50 m2). Both right ventricular (RV) and left ventricular (LV) chamber dimensions were within the normal range at both early and late time points and grew normally as assessed by a lack of class changes. Early wall thickness measurements were above the 95th percentile in seven of 13 patients (LV), 12 of 13 patients (septum), and four of 13 patients (RV). Wall thickness measurements remained above normal, and there were no significant class changes at late follow-up. Histological examination in five patients showed markedly increased septal myocyte width, indicating myocyte hypertrophy. Atrial and great vessel anastomotic sites showed no evidence of obstruction by Doppler and catheterization studies.

CONCLUSIONS

These data demonstrate that normal cardiac chamber dimensional growth occurs at greater than 3 years' follow-up after pediatric heart transplantation. Significant LV and septal (and to a lesser extent RV) hypertrophy persists and may have implications for long-term allograft growth and function.

Assessment of new immunosuppressive drugs in a rat cardiac allograft heterotopic model

We assessed FK506 (FK) and rapamycin (RPM) in a heterotopic abdominal rat heart transplant model using a major histocompatibility mismatch (DA to LEW). The end point of our study was histologic grading of rejection (Billingham and working formulation) at 1 week. Two doses of FK (2.0 and 8.0 mg/kg p.o., q.d.) and RPM (1.5 and 6.0 mg/kg i.p., q.d.) were compared to allografts without and with ciclosporin (12.5 mg/kg p.o., q.d.) treatment. Results show: (1) weak heartbeat and full rejection on day 5 in all untreated allografts; (2) weak heartbeat and high degree of rejection in groups receiving low doses of FK and RPM; (3) strong heartbeat and mild rejection in both high FK and RPM dose groups comparable to the results of the hearts treated with ciclosporin; (4) 1 animal in each high FK and RPM dose group showed possible signs of toxicity, and (5) the strength of the heartbeat was not a reliable indicator of the efficacy of an immunosuppressive drug. We conclude that even in a major histocompatibility mismatch model at the time of the strongest immune response (1 week), all three tested drugs can reduce the degree of rejection from severe (untreated allografts) to mild if given in an adequate dosage.

Granzyme A and perforin as markers for rejection in cardiac transplantation

The use of granzyme A and perforin as markers for rejection after cardiac transplantation has been investigated. Using in situ hybridization we have detected lymphocytes expressing granzyme A and perforin RNA that are infiltrating the donor heart after transplantation. A total of 29 different biopsies from 17 different patients who had undergone cardiac transplantation were examined. Twelve biopsies classified by conventional histological criteria as showing evidence of rejection were found to contain lymphocytes expressing granzyme A and perforin. Seven biopsies classified as showing no histological evidence of rejection infiltrating lymphocytes were found not to be expressing granzyme A or perforin. However, in 10 other biopsies from 5 different patients that had been classified as showing no evidence of rejection by the conventional grading system, lymphocytes expressing granzyme A and perforin were detected. In six of these cases the patient was found to have undergone a subsequent rejection episode. In the other four cases the biopsies were either taken at a very early stage after transplantation and the high doses of immunosuppression used routinely at that stage are likely to have averted any rejection episodes, or it was not possible to follow subsequent rejection episodes. These results, which are statistically significant (p = 0.06), demonstrate that granzyme A- and perforin-expressing lymphocytes can be identified in rejecting biopsies before histological damage is seen. The identification of perforin and granzyme A expression in vivo suggest a possible role for these proteins in the cytolysis that occurs during transplantation rejection. Furthermore, the data presented here suggest that it may be possible to use granzyme A and perforin as early predictive markers of transplantation rejection.

Long-term results of cardiac transplantation

Over 12,000 cardiac transplants have been performed worldwide and many recipients are alive between 10 and 20 years posttransplant. The results, complications, and pathology of the long-term survivors are discussed in this chapter.

Transplant coronary artery disease: histopathologic correlations with angiographic morphology

Accelerated coronary artery disease is a major cause of morbidity and mortality among cardiac transplant recipients. Ten patients who died or underwent retransplantation within 2 months of coronary angiography had direct correlation of angiographic (normal discrete lesions, diffuse concentric narrowing) with histologic appearance of coronary arteries. Of the 26 angiographically normal segments, 73% showed mild to moderate fibrous intimal thickening by light microscopy. The remainder had intermediate lesions or atheromatous plaques. Discrete stenoses usually corresponded to lipid-rich intermediate or atheromatous disease. In contrast, angiographically diffuse, concentrically narrowed lesions usually were areas of severe fibrous intimal thickening. Fresh or organizing thrombus was most often associated with discrete lesions and accounted for all complete occlusions. Histologic and angiographic comparisons of the degree of luminal narrowing showed generally good correlation for high grade stenoses. Lesions graded as having less than 25% diameter narrowing were often underestimated angiographically as compared with histologic determinations. Transplant coronary artery disease has a heterogeneous histologic and angiographic appearance, with angiographic underestimation of disease in some patients.

Selective T-cell depletion with Ox-38 anti-CD4 monoclonal antibody prevents cardiac allograft rejection in rats

New monoclonal antibodies directed to membrane molecules unique to lymphocyte subsets have provided the means to alter the immune response to alloantigens in a more selective fashion. This investigation demonstrates that monoclonal antibody-induced depletion of CD4 helper/inducer T lymphocytes before transplantation of a fully mismatched heart allograft allows permanent engraftment in rats without further immunosuppression. Five adult male ACI (RT1a) rats received cell-depleting doses of the mouse anti-rat CD4 monoclonal antibody, MRC Ox-38, for 1 month before undergoing heterotopic abdominal heart transplantation. No other immunosuppression was administered, and immunotherapy was discontinued the day of transplantation. After all five Lewis rat (RT1(1)) hearts were maintained free of rejection for more than 3 months, a second heterotopic transplant was performed, this time to the femoral vessels, using either fresh Lewis heart allografts (n = 3) or third-party, Brown-Norway (RT1n) hearts (n = 2). Histologic evaluation was performed 3 weeks later and revealed severe rejection of the femoral Brown-Norway grafts with no evidence of rejection in any of the femoral or original abdominal Lewis grafts. These results suggested that limited, pretransplant anti-CD4 immunotherapy allowed permanent engraftment of fully mismatched cardiac allografts in rats and conferred donor-specific unresponsiveness.

Captopril improves hypertension and cardiomyopathy in rats with pheochromocytoma

Hypertension and cardiomyopathy are prominent findings in humans and rats harboring pheochromocytomas, tumors that can secrete enormous quantities of catecholamines. We have previously found that alpha- and beta-adrenergic receptor antagonists may ameliorate the hypertension and cardiomyopathy found in New England Deaconess Hospital rats implanted with pheochromocytoma. The present studies were designed to determine the possible action of the angiotensin converting enzyme inhibitor captopril on these changes in rats harboring pheochromocytomas. Rats were implanted with transplantable pheochromocytomas and treated with captopril dissolved in the drinking water (1 mg/ml) for 4-6 weeks. Systolic blood pressure was monitored by using the tail-cuff technique. In the rats with pheochromocytoma, blood pressure progressively increased to 184 +/- 3 mm Hg after the tumor was implanted. However, in rats with pheochromocytoma treated with captopril in the drinking water before the development of hypertension, blood pressure did not increase (137 +/- 3 mm Hg). In rats with pheochromocytoma with established hypertension, captopril normalized the systolic blood pressure. Plasma norepinephrine was markedly elevated to a similar extent in both groups compared with unimplanted control rats. Plasma renin activities were slightly lower in rats with pheochromocytoma compared with unimplanted control rats. Treatment with captopril of rats with pheochromocytoma did not modify contraction of isolated rings of thoracic aorta exposed in vitro to either phenylephrine or angiotensin II. Treatment with captopril markedly attenuated the cardiomyopathy induced by pheochromocytoma. These results demonstrate that captopril prevents the development of hypertension despite markedly elevated concentrations of catecholamines. In addition, captopril attenuates catecholamine-induced cardiomyopathy in pheochromocytoma.(ABSTRACT TRUNCATED AT 250 WORDS)

Noninvasive detection of human cardiac transplant rejection with indium-111 antimyosin (Fab) imaging

Diagnosis of rejection after cardiac transplantation is currently made by right ventricular endomyocardial biopsy. To evaluate antimyosin imaging as a noninvasive means of detecting human cardiac rejection, the Fab fragment of murine monoclonal antimyosin antibodies was labeled with indium-111 and given intravenously to 18 patients (age 45 +/- 12 years) in 20 studies 7 days to 9 years after transplantation. Endomyocardial biopsy specimens were obtained at the time of each imaging study. Eight patients had positive scans confirmed by biopsy as rejection, and eight patients had negative scans and no evidence of rejection on biopsy. Discordance was observed in four studies, two with positive scans and no rejection on biopsy and two with negative scans and positive biopsy. The sensitivity, specificity, and overall accuracy of the technique were each 80%. Imaging with radiolabeled antimyosin antibody Fab fragments may be of value in the noninvasive identification of rejection in the cardiac transplant recipient.

Internal cardiac defibrillation: histopathology and temporal stability of defibrillation energy requirements

The automatic implantable cardioverter/defibrillator is tested intraoperatively to ensure effectiveness by performing a number of induced fibrillation-defibrillation trials. The temporal stability of defibrillation energy requirements and the histopathologic effects of multiple defibrillating shocks were studied in 12 dogs chronically instrumented with an internal spring-patch lead system identical to that used in humans. Dogs were studied on days 1, 11, 18, 25 and 32. Data were analyzed by logistic regression and the energy required for 50% (E50) and 80% (E80) success was compared. On day 32 the dogs were killed and the heart was removed for gross and microscopic pathologic examination. There was a significant decrease in energy requirements from day 1 to day 11, as the E50 decreased from 6.9 +/- 4.5 to 4.9 +/- 2.5 J (p less than 0.02) and the E80 decreased from 8.5 +/- 5.2 to 6.1 +/- 3.4 J (p less than 0.02). The energy requirements then remained stable over the remainder of the experiment. The dogs were administered 209 +/- 18 shocks (range 1 to 24 J) for a total cumulative dose of 1,524 +/- 571 J. In all cases, both grossly and microscopically, there was no evidence of pathologic changes in the myocardium or coronary vessels. In all cases there was a fibrous plaque beneath the patch electrodes, at times containing an area of patchy hemorrhage; in a single specimen a mixed inflammatory infiltrate accompanied the hemorrhage. Endothelialization of the spring electrode with mild right atrial endocardial fibrosis was also observed.(ABSTRACT TRUNCATED AT 250 WORDS)

A new method for assessing right-sided heart pressures using encapsulated microbubbles--a preliminary report

A new noncatheter method for measuring pressures of the right side of the heart uses specially manufactured microbubbles of carbon dioxide injected into the peripheral venous system. Sudden expansion of these bubbles in the cardiac chambers causes bubble oscillations at a frequency that is primarily a function of surrounding pressure. The oscillations are recordable by a microphone on the chest wall. The preliminary experience has been in dogs and further development is needed before we can begin clinical testing of the method. In its current form, the potential for measuring higher systolic pressures seems better than that for lower diastolic pressures.

Fatal myocardial infarction following therapy with prothrombin complex concentrates in a young man with hemophilia A

A fatal myocardial infarction in a 22-year-old man with hemophilia A and a factor VIII inhibitor is described. The catastrophic event occurred while the patient was receiving high doses of unactivated prothrombin complex concentrates. Autopsy examination revealed myocardial hemorrhage with no evidence of coronary artery disease or thrombosis. There also was postmortem evidence of previous myocardial infarctions. This is the fourth documented case of myocardial infarction occurring in a young hemophiliac patient using unactivated prothrombin complex concentrates. It is concluded that utilization of prothrombin complex concentrates in hemophiliac patients must be limited and closely monitored. Therapeutic guidelines are recommended.

Heart and lung transplantation for pulmonary hypertension

Seventeen patients received combined heart and lung transplants at Stanford University between March 1981 and December 1983. All recipients were suffering from end-stage pulmonary hypertension. Five patients died within the first few postoperative weeks, but the remainder were well between 2 and 35 months after operation. Immunosuppression consisted of cyclosporine with an initial course of rabbit antithymocyte globulin, and azathioprine was given for the first 2 postoperative weeks. Maintenance immunosuppression was achieved with cyclosporine and prednisone. Rejection, as diagnosed by cardiac biopsy, was treated with intravenous methylprednisolone. The functional status of the survivors has been good, and upon discharge from the hospital, all returned to normal activity. Our preliminary experience indicates that cardiopulmonary transplantation represents a realistic therapeutic approach for patients with end-stage pulmonary disease.

Clinical heart-lung transplantation

Combined heart and lung transplantation was carried out in thirteen patients at Stanford University between March 1981 and May 1983. The recipients were between 22 and 45 years old. All patients were suffering from end-stage pulmonary hypertension; nine patients had Eisenmenger's syndrome; the remaining four were transplanted for primary pulmonary hypertension. Three patients died within one month of surgery. The remainder are well at between 22 months and three weeks from operation. The duration of stay in the hospital for the surviving patients ranged from 38 to 85 days. The immunosuppressive protocol has been essentially the same for all recipients, and has consisted of cyclosporine with an initial course of rabbit antithymocyte globulin (RATG) with azathioprine given for the first two weeks, and then replaced with prednisone. Rejection, as diagnosed by cardiac biopsy, was treated with pulses of methylprednisolone. Early complications included bleeding that necessitated reexploration (five patients); damage to the vagus, recurrent laryngeal, or phrenic nerves (three patients); and failure of the donor lungs (one patient). Modifications of technique that have developed include removal of the recipient heart and lungs separately, and preservation of the lungs with a modified Collins' solution instead of a cardioplegic solution. The results of this operation are considerably superior to clinical efforts in lung transplantation. The combined operation may be preferable for the following reasons: All diseased tissue is removed, thus eliminating recurrent infection, and also perfusion/ventilation disparity. Transplantation of the entire heart and lung block preserves coronary-tracheal vascular anastomoses and makes airway dehiscence less likely. Diagnosis of rejection by cardiac biopsy seems to be a satisfactory method of diagnosis and treatment of pulmonary rejection.

Telemetry of electrophysiologic variables from conscious dogs: system design, validation, and serial studies

The necessity for conscious animal models in the study of cardiac physiology has been established for hemodynamics. The characterization of the electrophysiologic properties of the heart has not been performed in a serial fashion in a conscious animal model. Implanted telemetry sensing devices for recording atrial, ventricular, and His electrograms and stimulation systems for both atrium and ventricle allowed serial evaluation of eight dogs for up to 4 months. There were significant fluctuations in some electrophysiologic variables with time, particularly heart rate, sinus node recovery time, and pacing rate for induction of Wenckebach block. This variability did not appear to deviate with time after implantation, and no significant differences in the basal electrophysiologic state were found between the period early after surgery (0 to 2 1/2 weeks) and later (3 to 8 weeks).

Combined heart and lung transplantation

Combined heart and lung transplantation was carried out in ten patients at Stanford University Medical Center between March, 1981, and December, 1982. All patients had end-stage pulmonary hypertension. 7 of them had Eisenmenger's syndrome and 3 primary pulmonary hypertension. 3 patients died within a month of operation, but the remaining recipients are well 2 months to 2 years after transplantation. The hospital stay of the survivors ranged from 38 to 85 days. All survivors have returned to normal activity. The results of heart and lung transplantation have thus been considerably superior to those reported previously for lung transplantation. It is suggested that cardiopulmonary replacement is suitable treatment for end-stage pulmonary hypertension with or without associated congenital heart disease and that its application to other forms of advanced pulmonary failure may be warranted.

Correlation of an abnormal rest 201T1 myocardial image: pathological findings in cardiac transplant recipients

Rest myocardial 201T1 scintigraphy was undertaken in 15 males mean age 39 years (22-54) who had been accepted for cardiac transplantation. Complete pathological correlation was obtained in 14 after transplantation and in 1 who died before a suitable donor heart became available. The average time from scintigraphy to pathological evaluation was 42 days (9-103). All the 201T1 images were grossly abnormal and on the basis of these studies it was not possible to differentiate ischemic from idiopathic cardiomyopathy. Each of the three views of the 201T1 study was divided into three segments, therefore 135 areas were available for comparison (3 x 3 x 15). Eighty-eight of these were abnormal on scan and 78 of these were abnormal pathologically. The right ventricle was seen on all rest images but the degree of uptake bore no relationship to the measured thickness of the right ventricular wall. Structures such as the atrial wall and the enlarged papillary muscle were visualized in some patients. In two patients there was an improvement of the rest 201T1 image in delayed views and histologically these areas showed a mixture of muscle and fibrous tissue. The sensitivity of 201T1 imaging in this study was 89% and there was close correlation of the images with gross and microscopic pathological findings.

Effect of chronic potassium depletion on digitalis-induced inotropy and arrhythmias

The arrhythmogenic and inotropic effects of digoxin were studied in normokalemic controls, chronically hypokalaemic, and potassium-repleted dogs instrumented to maintain heart rate, mean aortic pressure, mean left atrial pressure and autonomic tone constant. The duration of digoxin infusion needed to produce ventricular tachycardia (VT) was 56.7 +/- 3.6 min in depleted dogs, 69.0 +/- 2.7 min in controls (P less than 0.005 compared with depleted dogs), and 60.5 +/- 3.0 min in repleted dogs. Baseline left ventricular dP/dt (LV dP/dt) was similar in all groups. After digoxin, LV dP/dt increased more in controls and repleted dogs than in chronically hypokalaemic dogs; eg, after 45 min of digoxin infusion LV dP/dt increased 12.7 +/- 4.4% in hypokalaemic dogs; eg, after 45 min of digoxin infusion LV dP/dt increased 12.7 +/- 4.4% in hypokalaemic dogs, 43.8 +/- 3.3% in controls (P less than 0.025) and 39.3 +/- 8.5% in repleted dogs (P less than 0.025). The inotropic response to isoprenaline was also attenuated in the chronically hypokalaemic dogs. Plasma digoxin was similar in all groups. LV digoxin was also similar in control and depleted dogs. Although inhibition of Na+, K+-ATPase and the initial velocity of 3[H]-ouabain specific binding was less in depleted dogs at VT than in controls (P less than 0.05), the magnitude of this difference was not sufficient to explain the attenuated inotropic response. No histological abnormalities were seen on light or electron microscopy in any of the groups. Therefore chronic hypokalaemia has two deleterous effects. It increases sensitivity to the arrhythmogenic effects of digoxin and impairs the inotropic response to digoxin, and isoprenaline.

Cardiac abnormalities in myotonic dystrophy. Electrophysiologic and histopathologic studies

Eight young adult male patients with myotonic dystrophy, mean age 26 years, underwent 24-hour Holter electrocardiographic monitoring and intracardiac electrophysiologic study. Right ventricular endomyocardial biopsies were performed at the end of the electrophysiologic study in five of them. The atrial to His[A-H] interval was 155 msec in one case and less than or equal to 55 msec in all patients. Twenty-four hour Holter electrocardiographic monitoring demonstrated more than 4 premature ventricular contractions per minute in two patients and marked cyclical sinus arrhythmia during sleep in two others. Electron microscopic analysis of the endomyocardial biopsy specimens disclosed no prominent sarcoplasmic reticulum abnormalities but prominent I bands compared to previously obtained controls. Myofibrillar degeneration was seen in all cases and was associated with abnormal mitochondria in two. Cardiac abnormalities can be detected very early in the evolution of myotonic dystrophy, even prior to the onset of cardiac symptoms. The reported abnormalities appear closely related to the pathologic process affecting other skeletal muscles.

Cardiac damage produced by direct current countershock applied to the heart

This study examined the pathophysiology of the myocaridal damage produced by direct current shock over a dose range of 10 to 90 watt-seconds, applied directly to the heart in 26 dosgs. The extent of injury produced was assessed with creatine kinase depletion and light and electron microscopy, and was correlated with in vivo imaging and tissue distributions of the isotopes technetium-99m pyrophosphate and thallium-201. Changes in intramyocardial temperature and regional myocardial blood flow were also measured. Uptake of technetium-99m pyrophosphate occurred exponentially with graded increases in shocks, and this agent was more sensitive than thallium-201 in detecting injury both on imaging and at tissue level. The threshold for significant injury was approximately 30 watt-seconds, and on electron microscopy a characteristic feature was marked dehiscence of the intercalated disks between the damaged myocytes. The use of different-size paddles did not appear to affect the total number of cells damaged. However, with large paddles the injury was more superficial and spread over a wider area. With short time intervals between successive shocks, a greater amount of injury occurred, in part because of a compounding of the thermal component of the damage. Hypothermia can reduce the degree of injury.

Polymeric albumin in the urine of patients with nephrotic syndrome

Dimer and polymer albumin was detected in the urine of a proportion of pantients with a nephrotic syndrome. Most of it was present as S-S bonded dimer and polymer; co-polymers, however, with IgG and alpha (1) anti-trypsin could be demonstrated. It is suggested that albumin polymerizes after it has passed the glomerular membrane. Albumin dimer was associated mainly with minimal change disease and early membranous glomerulopathy in patients, who in general responded well to therapy.

Successful retransplantation of the human heart

Cardiac retransplantation has been performed in five patients at Stanford University Medical Center. Long-term survival and rehabilitation have been achieved in two cases. In the first case retransplantation was performed 57 days after the initial procedure because of persistent acute graft rejection. The second patient underwent retransplantation 27 months postoperatively because of documented accelerated graft atherosclerosis. The major indications for cardiac retransplantation consist of intractable acute rejection and late postoperative graft atherosclerosis. These complications should prompt consideration of cardiac retransplantation in carefully selected cases.