Utility of long-term surveillance endomyocardial biopsy: a multi-institutional analysis.

BACKGROUND: The utility of long-term endomyocardial biopsy surveillance in heart transplant recipients has been questioned. This study was undertaken to identify risk factors for late rejection and to examine the impact of different biopsy surveillance protocols on outcomes using the registry of the Cardiac Transplant Research Database. METHODS: The study group consisted of all adult patients who underwent heart transplantation at the 33 centers participating in this investigation between January 1, 1993 and January 1, 2002, survived past the second post-transplant year, and were followed-up by a defined surveillance biopsy protocol. RESULTS: During a follow-up that consisted of 24,137 patient-years, 1,626 late rejections occurred. Shorter time since transplant, history of rejection, younger age and African-American ethnicity of the recipient were strong risk factors for late rejection. The practice of surveillance biopsy varied among institutions. Continued surveillance increased the rate of diagnosis of late rejection (RR = 1.3, p = 0.002). There was no reduction in the incidence of hemodynamically compromising rejection and no increase in survival in patients with long-term vs intermediate-term surveillance. Short-term surveillance was associated with an increased incidence of hemodynamically compromising rejection, particularly among high-risk patients, and increased mortality in African-American patients. CONCLUSIONS: There are no apparent benefits from surveillance biopsy beyond 5 years post-transplant. Surveillance biopsy between 2 and 5 years post-transplant was found to reduce mortality in African-American recipients. Non-African-American recipients at high risk for late rejection will likely benefit from surveillance up to 5 years post-transplant.

Heart transplantation in patients over 54 years of age. Mortality, morbidity and quality of life.

AIMS: As a consequence of recent advances in heart transplantation, upper age limits for the procedure have been liberalized in many centres. It was the purpose of this study to compare post-transplant mortality, morbidity and quality of life in a consecutive series of 72 patients > 54 years (mean age, 57.6 +/- 2.7 years) with a control group of 72 adult patients < or = 54 years (mean age, 42.4 +/- 9.5 years) transplanted at one centre between 1985 and 1991. METHODS AND RESULTS: Patients were followed for 41 +/- 27 months post-transplant. Actuarial 1-, 5- and 7-year survival rates were 78 +/- 5%, vs 81 +/- 5%, 52 +/- 7% vs 66 +/- 6% and 46 +/- 8% vs 63 +/- 6% in patients > 54 years and < or = 54 years, respectively (P = ns). Causes of death were not significantly different between the groups. Patients > 54 years experienced significantly fewer rejection episodes after the 6th month post-transplant (0.5 +/- 0.9 vs 0.9 +/- 1.0, P < 0.04), and incidence and treatment of rejection episodes as well as incidence of infection was comparable between the groups. Non-lymphoid malignancies, mainly skin cancer, occurred more often in the older age group (27% vs 13%, P < 0.05). Quality of life, as assessed by the Nottingham Health Profile, was better in 5/6 dimensions of social functioning in older patients and the difference reached statistical significance for the dimensions of emotional reactions (P = 0.005) and sleep (P = 0.0005). CONCLUSION: In conclusion, carefully selected patients > 54 years can undergo heart transplantation with mortality and morbidity comparable to younger patients. Quality of life post-transplant seems even to be slightly better in the older age group.

Expression of inducible nitric oxide synthase in human heart failure.

BACKGROUND: There is increasing evidence that alterations in nitric oxide synthesis are of pathophysiological importance in heart failure. A number of studies have shown altered nitric oxide production by the endothelial constitutive isoform of nitric oxide synthase (NOS), but there is very little information on the role of the inducible isoform. METHODS AND RESULTS: We analyzed inducible NOS (iNOS) expression in ventricular myocardium taken from 11 control subjects (who had died suddenly from noncardiac causes), from 10 donor hearts before implantation, and from 51 patients with heart failure (24 with dilated cardiomyopathy [DCM], 17 with ischemic heart disease [IHD], and 10 with valvular heart disease [VHD]). Reverse transcription-polymerase chain reaction was used to confirm the presence of intact mRNA and to detect expression of iNOS and atrial natriuretic peptide (ANP). ANP was used as a molecular phenotypic marker of ventricular failure. iNOS was expressed in 36 of 51 biopsies (71%) from patients with heart failure and in none of the control patients (P<.0001). iNOS expression could also be detected in 50% of the donor hearts. All samples that expressed iNOS also expressed ANP. iNOS gene expression occurred in 67% of patients with DCM, 59% of patients with IHD, and 100% of patients with VHD. To determine whether iNOS protein was expressed in failing ventricles, immunohistochemistry was performed on three donor hearts and nine failing hearts with iNOS mRNA expression. Staining for iNOS was almost undetectable in the donor myocardium and in control sections, but all failing hearts showed diffuse cytoplasmic staining in cardiac myocytes. Expression of iNOS could be observed in all four chambers. Western blot analysis with the same primary antibody showed a specific positive band for iNOS protein in the heart failure specimens; minimal iNOS protein expression was seen in donor heart samples. CONCLUSIONS: iNOS expression occurs in failing human cardiac myocytes and may be involved in the pathophysiology of DCM, IHD, and VHD.

Induction of nitric oxide synthase in the human cardiac allograft is associated with contractile dysfunction of the left ventricle.

BACKGROUND: The mechanisms underlying cardiac contractile dysfunction after transplantation remain poorly defined. Previous work has revealed that inducible nitric oxide synthase (iNOS) is expressed in the rat heterotopic cardiac allograft during rejection; resultant overproduction of nitric oxide (NO) might cause cardiac contractile dysfunction via the negative inotropic and cytotoxic actions of NO. In this investigation, we tested the hypothesis that induction of iNOS may occur and be associated with cardiac allograft contractile dysfunction in humans. METHODS AND RESULTS: We prospectively studied 16 patients in the first year after cardiac transplantation at the time of serial surveillance endomyocardial biopsy. Clinical data, the results of biopsy histology, and echocardiographic and Doppler evaluation of left ventricular systolic and diastolic function were recorded. Total RNA was extracted from biopsy specimens, and mRNA for beta-actin, detected by reverse transcription-polymerase chain reaction (RT-PCR) using human specific primers, was used as a constitutive gene control; iNOS mRNA was similarly detected by RT-PCR using human specific primers. iNOS protein was detected in biopsy frozen sections by immunofluorescence. Myocardial cGMP was measured by radioimmunoassay, and serum nitrogen oxide levels (NOx = NO2 + NO3) were measured by chemiluminescence. iNOS mRNA was detected in allograft myocardium at some point in each patient and in 59 of 123 biopsies (48%) overall. In individual patients, iNOS mRNA expression was episodic and time dependent; the frequency of expression was highest during the first 180 days after transplant (P = .0006). iNOS protein associated with iNOS mRNA was detected by immunofluorescence in cardiac myocytes. iNOS mRNA expression was not related to the ISHLT histological grade of rejection or to serum levels of NOx but was associated with increased levels of myocardial cGMP (P = .01) and with both systolic (P = .024) and diastolic (P = .006) left ventricular contractile dysfunction measured by echocardiography and Doppler. CONCLUSIONS: These data support a relation between iNOS mRNA expression and contractile dysfunction in the human cardiac allograft.

Impaired matching of perfusion and ventilation in heart failure detected by 133xenon.

In severe chronic heart failure (CHF) the ventilatory cost of CO2 elimination during exercise (VE/VCO2) is increased, suggesting ventilation/perfusion (V/Q) mismatch. The relationship of exercise VE/VCO2 regression slope m to deadspace ventilation was studied in 15 patients with CHF who underwent cardiopulmonary exercise testing and arterial blood gas monitoring. Regional lung ventilation and perfusion was studied, using 133xenon, at rest and peak exercise in a further group of 10 CHF patients and in five normal subjects. VE/VCO2 slope m correlated well with deadspace ventilation at peak exercise in the 15 patients with CHF. We therefore used exercise VE/VCO2 slope m to categorize CHF patients undergoing 133xenon imaging into groups with increased (slope m > 36) or normal (slope m < 36) exercise deadspace ventilation. In normals, resting V/Q determined by 133xenon showed a gravitational gradient, which improved on exercise as a result of relative increases and of relative reductions in regional perfusion; no significant changes in regional ventilation distribution were detected. In patients with CHF who had normal slope m (n = 5), rest and exercise V/Q were similar to the normal subjects. In CHF patients with increased slope m (n = 5) however, the resting gravitational gradient of V/Q was lost, and there were no significant changes in relative perfusion distribution on exercise. These findings suggest that the increased ventilatory cost of CO2 elimination found in certain patients with CHF is related to inability to coordinate and optimise the relative distribution of lung perfusion with respect to ventilation during exercise.

Prognostic importance of intimal thickness as measured by intracoronary ultrasound after cardiac transplantation.

BACKGROUND: Although intracoronary ultrasound (ICUS) has been validated for the early detection of transplant coronary artery disease (TxCAD), the prognostic importance of findings detected by this new imaging technique is unknown. METHODS AND RESULTS: This study examined the relation of clinical outcome in 145 heart transplant recipients (mean age, 45.1 +/- 11.1 years) with the amount of intimal thickness measured by ICUS during routine annual coronary angiography 1 to 10 years (mean, 3.1 +/- 2.2 years) after transplantation. From published autopsy data, a mean intimal thickness of > 0.3 mm was considered significant. During a mean follow-up time of 48.2 +/- 10.2 months, 23 deaths (12 cardiac) occurred, and 6 patients required retransplantation. Angiographic TxCAD developed in 22 of 125 patients (17.6%) in the subgroup with normal angiograms at the time of ICUS and a follow-up annual angiographic study. In the total population and the subgroup, mean intimal thicknesses of > 0.3 and < or = 0.3 mm, respectively, were associated with significantly inferior 4-year actuarial overall survival (73% versus 96%, P = .005; 72% versus 92%, P = .05), cardiac survival (79% versus 96%, P = .005; 80% versus 98%, P = .04), and freedom from cardiac death and retransplantation (74% versus 98%, P < .0001; 70% versus 96%, P = .001). In addition, ICUS predicted freedom from development of subsequent angiographic TxCAD in the subgroup that was initially normal (26% versus 72%, P = .02). A mean intimal thickness by ICUS of > 0.3 mm was associated with inferior clinical outcome regardless of the presence of angiographic TxCAD and predicted the development of subsequent angiographic TxCAD. Despite significantly longer duration after transplantation, higher rejection incidence, and lower average daily cyclosporine dose, none of these covariates were independent risk factors for outcome. CONCLUSIONS: These findings confirm the prognostic importance of mean intimal thickening of > 0.3 mm in heart transplant recipients and suggest that these patients should be candidates for early interventional strategies.

Exposure to shear stress alters endothelial adhesiveness. Role of nitric oxide.

BACKGROUND: Shear stress increases the release of nitric oxide (NO) by endothelial cells (ECs). We and others have provided evidence that endothelium-derived NO inhibits monocyte adhesion to the vessel wall. We therefore hypothesized that previous exposure to shear stress would inhibit endothelial adhesiveness for monocytes by virtue of its effect to increase NO release. METHODS AND RESULTS: Confluent monolayers of bovine aortic endothelial cells, human aortic endothelial cells, or human venous endothelial cells were exposed to laminar fluid flow. Culture media were collected for measurement of NO (by chemiluminescence) and the prostacyclin metabolite 6-keto-prostaglandin F1 alpha. NOx and 6-keto-prostaglandin F1 alpha accumulated in the conditioned medium during laminar fluid flow from 30 minutes to 24 hours in a time-dependent fashion. In another set of studies, ECs previously exposed to flow or to static conditions were washed with Hanks' buffer and exposed to THP-1 cells for 30 minutes. Adherent cells were counted by microscopy. Previous exposure to flow reduced endothelial adhesiveness for monocytes by 50% (P < .05). The effect of flow on endothelial adhesiveness occurred within 30 minutes. This effect was abrogated by nitro-L-arginine (an antagonist of NO synthesis), as well as by tetraethylammonium ion (an antagonist of the flow-activated potassium channel); the effects of these inhibitors were reversed by the NO donor SPM-5185. Although the cyclo-oxygenase inhibitor indomethacin totally inhibited the flow-induced production of prostacyclin by ECs, it minimally affected adherence of THP-1 cells. The early effect of flow on endothelial adhesiveness was not mediated by alterations in the expression of the endothelial adhesion molecules VCAM-1 or ICAM-1 as assessed by fluorescent activated cell sorting. CONCLUSIONS: Shear stress alters endothelial adhesiveness for monocytes; at early time points, this effect is largely due to flow-stimulated release of NO and, to a lesser extent, prostacyclin. This effect of flow occurs within 30 minutes and is probably due to alterations in the signal transduction or activation state (rather than the expression) of endothelial adhesion molecules.

The relationship of granzyme A and perforin expression to cardiac allograft rejection and dysfunction.

The mechanisms underlying contractile dysfunction following heart transplantation are poorly defined. To investigate the role of cytotoxic T cells (CTL) in cardiac transplant rejection, and during episodic contractile dysfunction, we performed a prospective study analyzing the expression of granzyme A and perforin, two functional markers of activated CTL. Sixteen consecutive patients were analyzed during the first year posttransplantation. All patients received induction therapy with OKT-3 and received standard three-drug immunosuppression therapy. Rejection status was monitored using routine surveillance endomyocardial biopsy and graded according to the ISHLT scale. Granzyme A and perforin mRNA were detected by reverse transcription PCR at the time of each routine biopsy. A total of 64/123 biopsies were positive for granzyme expression, while 38/123 samples were positive for perforin expression. LV function was monitored using M-mode derived fractional shortening and Doppler assessment of diastolic function (isovolumic relaxation time [IVRT] and pressure half-time [P1/2]). As expected, the presence of granzyme A message was associated with rejection score (ANOVA, P = 0.001). In addition, granzyme A expression was correlated with a decrease in diastolic function (chi 2 = 6.4, P < 0.02), but was not associated with systolic function. The presence of perforin message was not correlated with functional changes or with rejection grade, but was associated with granzyme expression (chi 2 = 9.11, P = 0.0025). These studies suggest that the presence of granzyme A message may be an important predictor of graft function.

Exercise ventilation after balloon dilatation of the mitral valve.

BACKGROUND: Exertional dyspnoea is a limiting symptom in many patients with mitral stenosis but its causes remain incompletely understood. Ventilation during exercise is abnormal in chronic heart failure of all causes and there is increased ventilatory cost of carbon dioxide production. PATIENTS: 23 patients with rheumatic mitral stenosis undergoing percutaneous balloon dilatation of the mitral valve were studied to investigate exercise ventilation. METHODS: Treadmill exercise tests with respiratory gas analysis were performed before and 1 day, 7 days, and 10 weeks after balloon dilatation of the mitral valve. The relation between ventilation (VE) and production (VCO2) was analysed by linear regression. RESULTS: The VE/VCO2 slope was linear in all patients and before balloon dilatation of the mitral valve it correlated inversely with peak minute oxygen consumption (VO2) (rs = -0.47, P < 0.05), exercise duration (rs = -0.66, P < 0.01), and mitral valve area (rs = -0.5, P < 0.05). The VE/VCO2 slope declined acutely after balloon dilatation of the mitral valve (n = 10) (mean (SD) 41 (4) v 36 (2.9), P < 0.05) and did not change again thereafter. At 10 weeks (n = 23) exercise duration (460 (230) v 630 (240) s, P < 0.01) and peak VO2 (12.7 (4.3) v 14.9 (4.8) ml/kg/min, P < 0.05) increased significantly. CONCLUSIONS: Patients with rheumatic mitral stenosis have a similar increase in the VE/VCO2 slope to that of patients with heart failure from other causes. Successful balloon dilatation of the mitral valve is associated with an acute reduction in the exercise VE/VCO2 slope.

Can an echocardiographic score predict who will benefit clinically from balloon dilation of the mitral valve?

Deciding whether a patient with sub-optimal mitral valve anatomy will benefit from percutaneous mitral valvotomy remains a demanding clinical problem. We assessed the ability of an established echo score applied to transoesophageal images to predict absolute increases in mitral valve area and improvement in exercise capacity. Twenty five consecutive patients undergoing routine percutaneous mitral valvotomy were studied. Changes in exercise tolerance were measured by serial cardiorespiratory treadmill exercise testing. Before the procedure, exercise duration was directly related to mitral valve area (rs = 0.44, P < 0.05). Following percutaneous mitral valvotomy there was an increase in valve area (0.9 +/- 0.2 to 1.4 +/- 0.3 cm2, P < 0.0001) and repeat exercise testing demonstrated increases in exercise duration (470 +/- 220 to 610 +/- 240 s, P < 0.001) and peak VO2 (12.6 +/- 4.2 to 15.1 +/- 4.5 ml/kg/min, P < 0.01). There was an inverse correlation between the echo score and the increase in valve area (rs = -0.52, P < 0.05) but no relationship between the echo score and the increase in exercise duration or peak minute oxygen consumption (VO2). These data demonstrate that a score applied to transoesophageal images echocardiographic images can predict changes in mitral valve area but that the score fails to predict functional improvement for an individual patient. This suggests, therefore, that patients without contraindications to valvotomy whose valves have a high echo score should still be considered for valvotomy as they may benefit considerably from the procedure.

Correlation of donor characteristics with transplant coronary artery disease as assessed by intracoronary ultrasound and coronary angiography.

The mechanisms responsible for transplant coronary artery disease (CAD) and its predisposing factors remain incompletely understood. The influence of donor characteristics as predisposing factors has not been studied systematically. We examined the correlation of donor demographic, clinical, and immunologic parameters with transplant CAD assessed by both intracoronary ultrasound (ICUS) and coronary angiography in 116 heart transplant recipients (age 44.7 +/- 12.0 years) studied 3.4 years (range 1.0 to 14.6) after transplantation. Quantitative ultrasound data were obtained by calculating mean intimal thickness from several distinct coronary sites. Coronary angiograms were categorized visually as normal or showing any transplant CAD. By multivariate regression analysis, donor undersize of > 20% of recipient weight (p < 0.02) and duration after transplantation (p < 0.005) were independently correlated with the amount of ICUS intimal thickness (r = 0.36, p = 0.0007), and older donor age with angiographic evidence for the disease (r = 0.34, p < 0.006). In a subgroup analysis of the 39 patients studied 1 year after transplantation, white donor race (p < 0.05), fewer human leukocyte antigen-DR mismatches (p < 0.002), shorter ischemic time (p < 0.04), and donor smoking history (p < 0.02) were independent predictors for severity of ICUS intimal thickening (r = 0.92, p = 0.0009); higher donor age (p < 0.006) and higher arterial partial pressure of oxygen (p < 0.003) were independent predictors for angiographic disease (r = 0.67, p < 0.002). In conclusion, donor characteristics may contribute to the probably multifactorial pathogenesis of transplant CAD.

Perfusion/ventilation mismatch during exercise in chronic heart failure: an investigation of circulatory determinants.

BACKGROUND: The ventilatory cost of carbon dioxide (CO2) elimination on exercise (VE/VCO2) is increased in chronic heart failure (CHF). This reflects increased physiological dead space ventilation secondary to mismatching between perfusion and ventilation during exercise. The objectives of this study were to investigate the relation of this increased VE/VCO2 slope to the syndrome of CHF or to limitation of the exercise related increase of pulmonary blood flow, or both. PATIENTS AND METHODS: Maximal treadmill exercise tests with respiratory gas analysis were performed in 45 patients with CHF (defined as resting left ventricular ejection fraction < 40% on radionuclide scan); 15 normal controls; 23 patients with coronary artery disease and normal resting left ventricular function; and 13 pacemaker dependent patients (six with and seven without CHF) directly comparing exercise responses in rate responsive and fixed rate mode. RESULTS: Patients with CHF had a steeper VE/VCO2 slope than normal controls: this was related inversely to peak VO2 below 20 mol/min/kg. In patients with coronary artery disease in whom peak VO2 (at respiratory exchange ratio > 1) was as limited as in the patients with CHF but resting left ventricular function was normal, the VE/VCO2 slope was normal. In pacemaker dependent patients fixed rate pacing resulted in lower exercise capacity and peak VO2 than rate responsive pacing; the VE/VCO2 slope was normal in patients without CHF but steeper than normal in patients with CHF; the VE/VCO2 slope was steeper during fixed rate than during rate responsive pacing in these patients with CHF. CONCLUSIONS: These findings suggest that the perfusion/ventilation mismatch during exercise in CHF is related to the chronic consequences of the syndrome and not directly to limitation of exercise related pulmonary flow. Only when the syndrome of CHF is present can matching between perfusion and ventilation be acutely influenced by changes in pulmonary flow.

Gene therapy inhibiting neointimal vascular lesion: in vivo transfer of endothelial cell nitric oxide synthase gene.

It is postulated that vascular disease involves a disturbance in the homeostatic balance of factors regulating vascular tone and structure. Recent developments in gene transfer techniques have emerged as an exciting therapeutic option to treat vascular disease. Several studies have established the feasibility of direct in vivo gene transfer into the vasculature by using reporter genes such as beta-galactosidase or luciferase. To date no study has documented therapeutic effects with in vivo gene transfer of a cDNA encoding a functional enzyme. This study tests the hypothesis that endothelium-derived nitric oxide is an endogenous inhibitor of vascular lesion formation. After denudation by balloon injury of the endothelium of rat carotid arteries, we restored endothelial cell nitric oxide synthase (ec-NOS) expression in the vessel wall by using the highly efficient Sendai virus/liposome in vivo gene transfer technique. ec-NOS gene transfection not only restored NO production to levels seen in normal untreated vessels but also increased vascular reactivity of the injured vessels. Neointima formation at day 14 after balloon injury was inhibited by 70%. These findings provide direct evidence that NO is an endogenous inhibitor of vascular lesion formation in vivo (by inhibiting smooth muscle cell proliferation and migration) and suggest the possibility of ec-NOS transfection as a potential therapeutic approach to treat neointimal hyperplasia.

Reliability and usefulness of immunofluorescence in heart transplantation.

BACKGROUND AND METHODS: To study the reliability and usefulness of immunofluorescence on heart biopsy specimens for routine monitoring of heart transplant recipients for rejection, frozen sections of 72 consecutive endomyocardial biopsy specimens from 18 heart transplant recipients during the first 6 weeks after transplantation (and later) and from 11 control specimens from donor hearts and other nontransplantation patients were studied. Fifteen patients received OKT3 induction. The diagnosis of vascular (humoral) rejection pattern as defined by Hammond was based on the microvascular deposition of immunoglobulin and C3 or C1q. Echocardiographic data and right-sided heart catheterization were obtained simultaneously. RESULTS: The results showed that immunofluorescence was positive for a vascular rejection pattern in 60% (43 of 72) overall, in heart transplant recipients it was positive in 59% (36 of 61), and in control subjects it was positive in 63% (7 of 11). Most of the patients who had positive immunofluorescence had no hemodynamic compromise. Humoral rejection was not predicted by positive immunofluorescence in our study. We also found no correlation with either positive or negative immunofluorescence for the short-term or long-term outcome during the first 6 weeks after transplantation. CONCLUSION: The usefulness of routine immunofluorescence in all surveillance heart biopsies is questionable as determined by this study.

Incidence and severity of transplant coronary artery disease early and up to 15 years after transplantation as detected by intravascular ultrasound.

OBJECTIVES: The purpose of this study was to quantify the severity of transplant coronary artery disease and to assess lesion characteristics early and up to 15 years after heart transplantation by using intracoronary ultrasound. BACKGROUND: Intravascular ultrasound has the ability to measure the components of the arterial wall and has been shown to be a sensitive method for detection of transplant coronary artery disease. METHODS: A total of 304 intracoronary ultrasound studies were performed in 174 heart transplant recipients at baseline and up to 15 (mean 3.3 +/- 0.2) years after transplantation. Mean intimal thickness and an intimal index were calculated, and lesion characteristics (eccentricity, calcification) were assessed for all coronary sites imaged (mean 3.0 +/- 0.1 sites/study). The Stanford classification was used to grade lesion severity. RESULTS: Compared with findings in patients studied at baseline (< 2 months after transplantation, n = 50), mean intimal thickness (0.09 +/- 0.02 vs. 0.16 +/- 0.02 mm, p < 0.01), intimal index (0.07 +/- 0.01 vs. 0.14 +/- 0.02, p < 0.01) and mean severity class (1.5 +/- 0.2 vs. 2.3 +/- 0.2, p < 0.01) were significantly higher at year 1 (n = 52) after transplantation. Thereafter, all three variables further increased over time and reached highest values between years 5 and 15. Calcification of lesions was detected in 2% to 12% of studies up to 5 years after transplantation, with a significant increase to 24% at years 6 to 10 (p < 0.05). CONCLUSIONS: Severity of transplant coronary artery disease appeared to progress with time after transplantation in this cross-sectional study. This characteristic was most prominent during the 1st 2 years after transplantation, whereas calcification of plaques occurred to a significant extent only later in the process. These data may serve as a reference for comparison of intravascular ultrasound findings in other studies of patients with transplant coronary artery disease.

Effects of the correction of renal anaemia by erythropoietin on physiological changes during exercise.

The effects of treating the anaemia of end-stage renal failure with erythropoietin were studied in nine dialysis patients. The increase in haemoglobin concentration (by 59% from 7.0 +/- 1.2 to 11.1 +/- 1.1 g dl-1) was associated with increases in exercise duration (by 41%) and maximum oxygen consumption (by 34%). Treatment reduced resting heart rate but did not significantly alter heart rate at maximum exercise, nor resting or exercise blood pressure. Resting arterial potassium concentrations were slightly increased after treatment, but they increased similarly in relation to minute ventilation during exercise. Lactic acidaemia developed during exercise at both levels of haemoglobin, and was accompanied by similar reductions in arterial pH and bicarbonate levels but constant PaO2 and PaCO2. Ventilation was coupled to the metabolic rate of carbon dioxide production, ventilatory dead-space and arterial PCO2 before and after treatment of anaemia, the ventilatory requirement for carbon dioxide elimination being unchanged. Treatment of anaemia did not alter resting arterial lactate concentration; the concentration of lactate at maximum exercise was increased slightly following treatment but this increase did not reach statistical significance. The rate of increase in arterial lactate concentration as a function of oxygen consumption, assessed both with respect to the 'lactate threshold' and 'lactate slope index', was significantly delayed by treatment. Treatment of anaemia also delayed the 'anaerobic threshold', and there was good correlation between lactate and anaerobic thresholds. Treatment of renal anaemia by erythropoietin thus results in improved tissue oxygen supply during exercise, reflected by delay in the onset of lactic acidaemia.

The heart as a bass organ.

Many florid physical signs of aortic regurgitation have been described. We describe a florid investigational finding of virtually monotonous intracardiac reverberation originating at the aortic valve leaflets.

The ventilatory cost of exercise compared in chronic heart failure and chronic renal anaemia.

The cardiorespiratory responses to maximal treadmill exercise were compared in matched groups of patients with chronic renal anaemia or treated chronic heart failure, and in normal controls. Exercise capacity was similarly reduced in both patient groups compared to normal controls, the raised respiratory exchange ratio at peak exercise implying anaerobic metabolism due to limited oxygen delivery in heart failure and limited oxygen carrying capacity in anaemia. Minute ventilation (VE) was related linearly to minute CO2 production (VCO2) in all subjects (each r > 0.92) from all three groups. The slope of the VE/VCO2 relationship was normal in anaemia but steeper in heart failure, reflecting ventilation/perfusion mismatching in chronic heart failure.

Reduced exercise capacity in patients with tricuspid regurgitation after successful mitral valve replacement for rheumatic mitral valve disease.

OBJECTIVE: To determine how severe tricuspid regurgitation influences exercise capacity and functional state in patients who have undergone successful mitral valve replacement for rheumatic mitral valve disease. DESIGN: 9 patients in whom clinically significant tricuspid regurgitation developed late after mitral valve replacement were compared with 9 patients with no clinical evidence of tricuspid regurgitation. The two groups were matched for preoperative clinical and haemodynamic variables. Patients were assessed by conventional echocardiography, Doppler echocardiography, and a maximal treadmill exercise test in which expired gas was monitored by mass spectrometry. SETTING: University Hospital of Wales, Cardiff. SUBJECTS: 18 patients who had been reviewed regularly since mitral valve replacement. MAIN OUTCOME MEASURE: Objective indices of exercise performance including exercise duration, maximal oxygen consumption, anaerobic threshold, and ventilatory response to exercise. RESULTS: Mitral valve prosthetic function was normal in all patients and estimated pulmonary artery systolic pressure and left ventricular function were similar in the two groups. Right ventricular diameter (median (range) 5.0 (4.3-5.6) v 3.7 (3.0-5.4) cm, p less than 0.01) and the incidence of paradoxical septal motion (9/9 v 3/9, p less than 0.01) were greater in the group with severe tricuspid regurgitation. Exercise performance--assessed by exercise duration (6.3 (5.0-10.7) v 12.7 (7.2-16.0) min, p less than 0.01), maximum oxygen consumption (11.2 (7.3-17.8) v 17.7 (11.8-21.4) ml min-1 kg-1, p less than 0.01), and anaerobic threshold (8.3 (4.6-11.4) v 0.7 (7.3-15.5) ml min-1 kg-1, p less than 0.05)--was significantly reduced in the group with severe tricuspid regurgitation. The ventilatory response to exercise was greater in patients with tricuspid regurgitation (minute ventilation at the same minute carbon dioxide production (41.0 (29.9-59.5) v 33.6 (26.8-39.3) l/min, p less than 0.01). CONCLUSIONS: Clinically significant tricuspid regurgitation may develop late after successful mitral valve replacement and in the absence of residual pulmonary hypertension, prosthetic dysfunction, or significant left ventricular impairment. Patients in whom severe tricuspid regurgitation developed had a considerable reduction in exercise capacity caused by an impaired cardiac output response to exercise and therefore experienced a poor functional outcome. The extent to which this was attributable to the tricuspid regurgitation itself or alternatively to the consequences of right ventricular dysfunction was not clear and requires further investigation.