Clinicopathologic correlations in congestive cardiomyopathy. A study on endomyocardial biopsies

Morphologic findings of the ischemic myocardium

This study assesses the relation between qualitative and quantitative findings of myocytes and interstitial connective tissue in the ischemic heart disease. Qualitative and quantitative changes of myocytes and interstitial connective tissue were studied on the serial cross myocardial sections from 20 autopsied hearts with ischemic lesions, stained by immunohistochemistry using a monoclonal antibody (von Willebrand factor) and with hematoxylin-eosin method. Myocardial sections included proximal and distal part of occlusion and area of occlusion of coronary vessels. The volume densities (V V) of the cardiac myocytes and interstitial fibrosis in the group with coronary occlusion were examined stereologically and compared with control group. The findings showed a significant reduction in the volume density of myocytes and an increase in the volume density of interstitial fibrosis in patients with coronary occlusion compared with control group. Significant reduction in the volume density of myocytes and an increase in volume density of interstitial fibrosis were greater in the distal part of occlusion and area of occlusion, than in the proximal part of the occlusion. Our stereological results give useful quantitative information's of changes in myocardium parts during coronary occlusion as well as in normal conditions, and represent objective proof of significant changes in ischemic myocardium described by qualitative analyses.

IL-1 beta increases abundance and activity of the negative transcriptional regulator yin yang-1 (YY1) in neonatal rat cardiac myocytes

Current research from both clinical and basic science perspectives indicates that cytokines play an important role in the genesis of cardiovascular pathology. Specifically, levels of cytokines such as interleukin-1 (IL-1), tumor necrosis factor- alpha (TNF- alpha), and interleukin-6 (IL-6) have been found to be elevated in both acute myocardial injury as well as situations of chronic dysfunction. Further, therapies directed primarily at interfering with cytokine action have suggested that such an immunomodulatory approach may be beneficial in some of these circumstances of myocardial injury. We recently reported that IL-1 beta induces a hypertrophic state in cultured neonatal rat cardiac myocytes that differs from other well described hypertrophic phenotypes in terms of myocardial gene expression (such as skeletal alpha -actin, sACT), an effect that appeared to co-localize with that of the negative regulator yin yang-1 (YY1).(1)In the present study, we further localize the area in the sACT promoter responsible for the IL-1 effect. These investigations indicate that sequences in and around the third upstream serum response element (SRE3) bind YY1 and are required for IL-1 beta mediated repression. This element is also capable of transferring both IL-1 beta and YY1-mediated transcriptional repression to a heterologous promoter. In support of an IL-1 beta induced post-translational modification of YY1 that results in an increase in DNA-binding activity,(32)P-labeling experiments reveal an increase in phosphorylated YY1 in IL-1 beta treated cells and phosphatase-treated myocyte nuclear proteins lose their ability to bind to the YY1 site. In summary, these results provide evidence that sequences within the SRE3 of the skeletal actin promoter represent an IL-1 beta response element and suggest that IL-1 beta activates the negative transcription factor YY1 by both transcriptional and post-transcriptional mechanisms.

Myofibrillar protein structure and assembly during idiopathic dilated cardiomyopathy

A neutral protease, mekratin, active in human hearts at end stage idiopathic dilated cardiomyopathy (IDC), mediates the breakdown of cardiac myosin LC2. Myosin purified from IDC heart tissue forms unusually short synthetic thick filaments. Therefore, determination of filament length and mekratin distribution in IDC heart muscle were initiated. Native thick filaments were prepared directly from control and IDC tissues and analyzed. Also, paraffin-embedded tissue sections were stained with a fluorescently-labeled anti-protease antibody to establish its distribution in myocardial tissues. Control sections had only very weak, background levels of fluorescence whereas IDC sections stained intensely throughout, indicating a wide ranging distribution of the protease within the myocyte cytoplasm. SDS-PAGE revealed LC2 to be present in stoichiometric amounts in control but greatly reduced in IDC heart muscle. Native thick filaments from control myocardium were structurally stable. They had a median length of 1.65 microm with well-defined bare zones and displayed the 43 nm helical periodicity typical of the relaxed arrangement of myosin heads close to the filaments' shafts. In contrast, native IDC filaments were less stable, and had a median length of 0.9 microm. These filaments were highly disordered: they had no surface periodicity and myosin heads were positioned away from the filaments' shafts. The shorter, less stable, aperiodic thick filaments from IDC hearts appear to result from depletion of LC2 caused by increased activity of mekratin in the IDC myocardium.

Protective effects of Gingko biloba extract EGb 761 on myocardium of experimentally diabetic rats. I: ultrastructural and biochemical investigation on cardiomyocytes

Chronic diabetes in man and animal models develops cardiomyopathic alterations which cannot be absolutely avoided by insuline therapy. Since diabetic damage is partly attributed to oxidative stress antioxidative treatment could be able to reduce the alterations. Aim of this study was to investigate the cardioprotective effects of EGb 761, known as a radical scavenger, against diabetic alterations in rats. The diabetes was induced by i.p. injection of 60 mg/kg body weight streptozotocin. Duration of diabetes was 4 months, the protected group received 100 mg/kg body weight EGb 761 with the drinking water over 3 months. Electron and light microscopic morphometry of left-ventricular samples revealed typical diabetic alterations consisting in decrease of volume fraction of myofibrils, SR and t-tubules and diminishing of cardiomyocyte diameter, increase of interstitial volume, mitochondrial size and volume fraction, and of vacuoles and of lipid drops. EGb treatment could gradually prevent the loss of myofibrils and reduction of myocyte diameter but has only little influence on interstitial and mitochondria volume. The diabetic-induced increase of lipid and vacuoles and the decrease of SR and t-tubules were not influenced. Biochemical parameters of oxidative stress: malondialdehyde (MDA) was only insignificantly altered by diabetes and EGb. The superoxide dismutase (SOD) activity was increased by diabetes and more increased by EGb treatment. Creatine kinase (CK) activity was diminished by diabetes but slightly increased by EGb. The polymerase chain reaction (PCR) of i-NOS was not different between the diabetic and protected diabetic groups.

Left ventricular function and endomyocardial biopsy in early and advanced dilated cardiomyopathy

We evaluated left ventricular function and endomyocardial biopsy in 20 patients with early and advanced dilated cardiomyopathy, with the purpose of assessing the correlation between histologic variables and systolic and diastolic filling indexes. Group 1 included 10 patients with no clinical history of heart failure and left ventricular ejection fraction > or = 45% and group 2, 10 patients with a clinical history of heart failure and left ventricular ejection fraction <45%. Group 1 showed lower left ventricular end-systolic and end-diastolic volumes indexes (49+/-14 versus 86+/-23 ml/m2, P<0.001; 98+/-25 versus 127+/-35 ml/m2, P=0.049), higher left ventricular ejection fraction (50+/-4 versus 32+/-4%, P<0.001) and lower coefficient of variation of percentage shortening of left ventricular transverse hemiaxes (0.3+/-0.1 versus 0.5+/-0.1, P=0.001) compared with group 2. Group 1 had higher A wave peak velocity (78+/-18 versus 60+/-20 cm/s, P=0.048), lower E/A ratio (0.9+/-0.3 versus 1.5+/-0.6, P=0.02) and slower E wave deceleration time (204+/-51 versus 155+/-50 ms, P=0.047) compared with group 2. Semiquantitative histologic scores did not differ significantly between groups. There was no significant correlation between histologic variables and left ventricular systolic and diastolic indexes. Thus, dilated cardiomyopathy shows borderline to severe left ventricular systolic impairment and distinct left ventricular diastolic filling abnormalities, according to the clinical stage. This study suggests a marked dissociation between histologic findings and functional abnormalities in early and advanced dilated cardiomyopathy.

Increased accumulation of acidic fibroblast growth factor in left ventricular myocytes of patients with idiopathic cardiomyopathy

To clarify the pathophysiologic role of fibroblast growth factors in idiopathic cardiomyopathy, we evaluated endomyocardial biopsy specimens obtained from 24 patients (nine with hypertrophic cardiomyopathy [HCM], 12 with dilated cardiomyopathy [DCM], and three with hypertensive hypertrophy) and six controls. All the specimens were stained for acidic fibroblast growth factor (aFGF) and basic FGF (bFGF) with immunohistochemistry. In situ hybridization was carried out for detection of aFGF mRNA. The average diameter of the myocytes, the percent area of interstitial fibrosis, and capillary vessel density were assessed in each biopsy specimen with morphometric methods. Positive staining of aFGF was observed in the myocytes of the biopsy specimens taken from 15 of 21 (71%) patients with cardiomyopathy (six of nine HCM, nine of 12 DCM) and all hypertensive hypertrophy patients but in none of the controls (p < 0.01). The average diameter of the myocytes was significantly larger in the patients with positive aFGF staining than in those with negative staining (23.1 +/- 1.5 versus 18.3 +/- 1.2 microm, p < 0.05). The percent area of fibrosis and the density of capillaries did not differ between the two groups. Intense expression of aFGF mRNA was observed in the myocytes from the patients with positive aFGF protein. In conclusion, the expression of FGF was significantly increased in myocytes obtained from the left ventricle of patients with cardiomyopathy. Acidic FGF may contribute to the hypertrophy of myocytes as the repair response to myocardial injury in patients with idiopathic cardiomyopathy.

Residual 201Tl activity in irreversible defects as a marker of myocardial viability. Clinicopathological study

BACKGROUND

The objective of the present study was to characterize the relation between the residual 201Tl activity in irreversible perfusion defects and the extent of irreversible myocardial damage indicated by the volume fraction of myocardial interstitial fibrosis in patients with chronic coronary artery disease.

METHODS AND RESULTS

Stress planar 201Tl scintigraphy with tracer reinjection at rest was performed in 37 patients with > or = 75% stenosis of the left anterior descending coronary artery, and anteroseptal 201Tl activity was quantified by computer-assisted placement of regions of interest from the serial myocardial images. During coronary artery bypass grafting (performed within 6 +/- 3 weeks after scintigraphy), two transmural biopsy specimens were taken from the anterior wall of the left ventricle and the amount of interstitial fibrosis was assessed by use of light microscopic morphometry. A wide spectrum of interstitial fibrosis was obtained, ranging from 15 vol% to 60 vol%. Interstitial fibrosis was similar in patients with reversible (n = 11) or irreversible (n = 15) tracer defects in conventional stress-redistribution images. However, interstitial fibrosis was significantly lower in patients who had enhanced regional 201Tl activity after tracer reinjection compared with those who did not have enhancement of tracer activity after reinjection (28 +/- 8 vol%, n = 7, versus 41 +/- 12 vol%, n = 8; P = .031). The correlation between relative poststenotic 201Tl activity and interstitial fibrosis after tracer reinjection was significantly improved compared with conventional redistribution images (r = -.622 versus r = -.851, n = 15; P < .01).

CONCLUSIONS

The present data demonstrate that the level of regional 201Tl activity in redistribution and, in particular, reinjection images is significantly related to the mass of preserved viable myocytes in poststenotic left ventricular myocardium. Therefore, the residual 201Tl activity provides information about viability within irreversible perfusion defects and may itself serve as marker of myocardial viability.

Histomorphometric features predict 1-year outcome of patients with idiopathic dilated cardiomyopathy considered to be at low priority for cardiac transplantation

Cardiac transplantation for patients with idiopathic dilated cardiomyopathy (IDC) and poor left ventricular function usually is postponed until symptoms have become intolerable. However, the short-term prognosis of this subset of patients has been defined poorly. Accordingly, the 1-year outcome was investigated in 30 patients with IDC with an ejection fraction < or = 25% who showed a stabilized clinical condition at assessment for transplantation and were therefore considered at low priority for surgery. During follow-up, 10 patients (group A) showed a poor outcome: 2 died suddenly, and 8 had hemodynamic failure (4 of whom underwent transplantation and 4 of whom died from heart failure while on the waiting list). The remaining 20 patients (group B) had a benign outcome. At assessment for cardiac transplantation, clinical and electrocardiographic features, left ventricular dimension, and ejection fraction were similar between the two groups. However, group A patients had higher left ventricular end-diastolic pressure (p < 0.03) and lower cardiac index (p < 0.02) and stroke volume index (p < 0.03) with respect to group B patients. In addition, the former had a lower myofibril volume fraction (p < 0.001) and a higher nuclear area (p < 0.001) compared with the latter. Multivariate analysis selected myofibril volume fraction (p < 0.001) and nuclear area (p < 0.005) as the only independent predictors of a poor 1-year outcome. The combination of myofibril volume fraction < or = 89% and nuclear area > 50 microns 2 was found in all group A patients (sensitivity 100%) but in only 2 group B patients (specificity 90%). It is concluded that in patients with IDC considered at low priority for cardiac transplantation: (1) the 1-year freedom from a cardiac event is lower than that currently expected with surgery; (2) histomorphometric features, that is, the concurrency of low myofibril volume fraction and increased nuclear area, predict short-term outcome; and (3) endomyocardial biopsy at assessment for cardiac transplantation might improve the rationalization of the timing of the procedure.

Ultrastructural abnormalities of mitochondria and deficiency of myocardial cytochrome c oxidase in a patient with ventricular tachycardia

A 30-year-old woman presented with life-threatening ventricular tachycardia without overt heart disease. Ultrastructural investigation of endomyocardial biopsy disclosed abnormally structured and often enlarged mitochondria. Morphometry revealed the ratio of volume density of mitochondria to myofibrils to be markedly increased to 0.667 as compared with five controls (mean: 0.46; range: 0.445-0.479). Investigation of mitochondrial respiratory chain enzymes revealed a 90% reduction in activity of cytochrome c oxidase. Our data suggest that mitochondrial cardiomyopathy may induce malignant ventricular arrhythmias.

Coronary capillaries in patients with congestive cardiomyopathy or angina pectoris with patent main coronary arteries. Ultrastructural morphometry of endomyocardial biopsy samples

BACKGROUND

The coronary microvasculature may be abnormal even in the presence of angiographically normal epicardial arteries. Abnormalities of small coronary vessels have been invoked as a cause of angina.

METHODS AND RESULTS

To quantitatively evaluate the morphology of capillaries in patients with idiopathic dilated cardiomyopathy (DCM) or the syndrome of angina and small vessel disease (SVD), we performed electron microscopic morphometry of capillaries in right ventricular biopsy samples taken from 32 patients. Ten had angina, normal epicardial coronary arteries, and evidence for SVD; 12 had DCM; and 10 had normal hearts. In patients with DCM, the ratio of microvessels to myocytes was not different than that of controls (0.49 +/- 0.06 versus 0.51 +/- 0.05). Mean cross-sectional areas of the capillaries (lumen plus wall) and lumen were significantly greater than those of controls (45.3 +/- 15.1 versus 22.7 +/- 8.3 micron 2, p less than 0.001; 17.6 +/- 6.9 versus 11.6 +/- 6.2 micron 2, p less than 0.05, respectively). Fibrous content of the myocardium, as assessed by quantitative light microscopy, was significantly increased (16.3 +/- 3.3% versus 5.0 +/- 2.4%, p less than 0.001). In contrast, in patients with SVD, the capillary-to-myocyte ratio was reduced (0.33 +/- 0.08, p less than 0.001). Although mean cross-sectional areas of the entire capillary (32.4 +/- 19.7 micron 2) and the lumen (8.9 +/- 7.8 micron 2) were not statistically different than those of controls, there was an absence of capillaries less than 15 micron 2 in cross-sectional area, and the frequency distribution of the lumen area was skewed to the left. Swollen endothelial cells frequently encroached upon the lumen. There was a mild increase in fibrous content (9.5 +/- 3.7%, p less than 0.05).

CONCLUSIONS

Enlarged capillaries and a normal ratio of capillaries to myocytes appear to be features of DCM. Of the patients with SVD, there was both a relative lack of capillaries and capillary lumen narrowing from swollen endothelium. These changes may induce ischemia and angina and may result in mild fibrosis.

Impairment of the myocardial ultrastructure and changes of the cytoskeleton in dilated cardiomyopathy

This study was designed to determine the morphological correlate of chronic heart failure. Myocardial tissue from eight patients undergoing transplantation surgery because of end-stage dilated cardiomyopathy was investigated by electron microscopy and immunocytochemistry using monoclonal antibodies against elements of the cytoskeleton: desmin, tubulin, vinculin, and vimentin. The tissue showed hypertrophy, atrophy of myocytes, and an increased amount of fibrosis. Ultrastructural changes consisted of enlargement and varying shape of nuclei, numerous very small mitochondria, proliferation of T tubules, and accumulation of lipid droplets and glycogen. The most obvious ultrastructural alteration was the decrease of myofilaments, ranging from rarefication to complete absence of sarcomeres in cells filled with unspecified cytoplasm. Immunocytochemistry showed that desmin was localized at the Z lines. In diseased myocardium, the amount of desmin was increased, but it was disorderly arranged. Tubulin formed a fine network throughout the myocytes and was significantly increased in cardiomyopathic hearts. Vinculin, a protein closely associated with the cytoskeleton, occurred not only at the sarcolemma and the intercalated disc but also within the myocardial cells. Ultrastructural changes and alterations of the cytoskeleton were severe in about one third of all cells. About one third of all cells showed moderately severe changes, and the remaining cells were normal. Vimentin was present in the interstitial cells and was increased in relation to the increase of fibrosis. We conclude that the increase of fibrosis, the degeneration of hypertrophied myocardial cells, and the alterations of the cytoskeleton are the morphological correlates of reduced myocardial function in chronic heart failure.

Mildly dilated congestive cardiomyopathy. Use of prospective diagnostic criteria and description of the clinical course without heart transplantation

Prognosis in classically described dilated congestive cardiomyopathy has been reported to be related to ventricular size. Mildly dilated congestive cardiomyopathy (MDCM) has been defined as end-stage heart failure of unknown etiology (New York Heart Association class IV, left ventricular ejection fraction less than 30%), occurring with neither typical hemodynamic signs of restrictive myopathy nor significant ventricular dilatation (less than 15% above normal range). The present study includes follow-up in 12 nontransplant patients. In the first 4 months after diagnosis, two patients improved and are living, and two showed cardiac dilation and clinical deterioration and died. Six of the remaining eight with persistent MDCM died (four with intractable heart failure and two, sudden deaths) without change in ventricular size before death, despite medical therapy over 20 +/- 8 months. Eight comparable transplanted patients with persistent MDCM demonstrated improved total survival by life table analysis (p less than 0.05). A family history of congestive cardiomyopathy was found in nine of 16 patients (56%) with persistent MDCM. Nontransplant patients were older (p less than 0.02), but other findings were similar in the two groups. Endomyocardial biopsies available in 14 of 16 cases showed little or no myofibrillar loss in spite of severe hemodynamic impairment. The degree of myofibrillar loss did not correlate with hemodynamic parameters but showed good correlation with left ventricular size, that is, five of six patients with no myofibrillar loss had normal ventricular size, whereas all eight patients with mild myofibrillar loss had mild cardiomegaly (p less than 0.002). Our current experience suggests a somewhat variable but negative prognosis after prospective diagnosis of MDCM, with poor survival in patients with persistence of the original diagnostic features during follow-up. Preservation of heart size in MDCM is probably related to lack of significant myofibrillar loss. Thus, irrespective of heart size or myofibrillar preservation on biopsy, heart transplantation should be strongly considered in MDCM if signs of severe cardiac dysfunction persist despite therapy.

Calcium sensitivity and unloaded shortening velocity of hypertrophied and non-hypertrophied skinned human atrial fibres

The mechanical properties of myocardium of different animals are modified by a chronic increase in haemodynamic load. In this study differences in calcium sensitivity and maximum unloaded shortening velocity of hypertrophic and non-hypertrophic chemically skinned human atrial fibres are characterized. Investigating right atria of 34 patients, possible correlations are studied between preoperative atrial pressure, degree of hypertrophy (estimated from the muscle fibre diameter), calcium responsiveness (pCa50 eliciting half-maximum contraction) and Vmax (unloaded shortening velocity). Hypertrophic fibres from atrial appendages of patients having an increased right atrial pressure (RAP 8.5 +/- 1.6 mm Hg) and suffering from mitral valve disease (stenosis and insufficiency combined) had a fibre diameter of 18.0 +/- 0.9 microns. They also had a higher calcium sensitivity (pCa50 5.65 +/- 0.08) and a lower unloaded shortening velocity (1.7 +/- 0.1 muscle lengths/s) than non-hypertrophic fibres from the appendages of patients with normal right atrial pressure (RAP 3.2 +/- 0.5 mm Hg) and coronary heart disease (CHD: pCa50 5.45 +/- 0.04; Vmax = 3.4 +/- 0.2 muscle lengths/s; fibre diameter 12.8 +/- 0.4 microns). Thus non-hypertrophic fibres from control CHD patients differed significantly (p less than 0.01) from hypertrophied atrial fibres of patients with mitral valve disease and with combined valve disease (MAV, pCa50 = 5.58 +/- 0.05, Vmax 2.0 +/- 0.3 muscle lengths/s, fibre diameter 14.6 +/- 0.9 microns) or aortic valve disease (stenosis combined with insufficiency, fibre diameter 14.8 +/- 1.4 microns, pCa50 5.56 +/- 0.03, Vmax 2.0 +/- 0.24 muscle length/s; RAP 11.0 +/- 2.6 mm Hg).(ABSTRACT TRUNCATED AT 250 WORDS)

Left ventricular myocardial structure in aortic valve disease before, intermediate, and late after aortic valve replacement

Left ventricular biplane cineangiography, micromanometry, and endomyocardial biopsies were performed in 27 patients with aortic stenosis (AS) and in 17 patients with aortic insufficiency (AI). Twenty-three patients with AS and 15 with AI were restudied at an intermediate time (18 months after successful valve replacement), and nine patients with AS and six with AI were restudied late (70 and 62 months after surgery). Biopsy samples were evaluated for muscle fiber diameter, percent interstitial fibrosis, and volume fraction of myofibrils. In control biopsy samples obtained from five donor hearts at transplantation, these morphometric variables averaged 21.2 microns, 7.0%, and 57.2%, respectively. After surgery, mass determined by cineangiography decreased from 186 to 115 and 94 g/m2 in patients with AS and from 201 to 131 and 93 g/m2 in patients with AI. At the three studies, muscle fiber diameter was 30.9, 28.0, and 28.7 microns in patients with AS and was 31.4, 27.6, and 26.4 microns in patients with AI. Percent interstitial fibrosis was 18.2, 25.8, and 13.7% in patients with AS and was 20.4, 23.7, and 19.2% in patients with AI. Left ventricular fibrous content decreased from 34.2 to 29.8 and to 12.7 g/m2 in patients with AS and from 42.1 to 28.9 and to 18.9 g/m2 in patients with AI. Volume fraction of myofibrils was 57.7, 56.8, and 49.0% in patients with AS and was 56.8, 56.6 and 48.8% in patients with AI. Thus, the decrease of muscle mass determined by cineangiography at the intermediate time after valve replacement is mediated by regression of myocardial cellular hypertrophy in patients with AS and AI and in addition by a decrease of fibrous content in patients with AI. Late after surgery, left ventricular fibrous content also decreases in patients with AS. This late decrease associated with minor changes of end-diastolic volume may be important for improvement of increased diastolic myocardial stiffness. Even 6-7 years after valve replacement, incomplete regression of structural abnormalities of left ventricular hypertrophy still exists compared with the normal myocardium. The residually increased relative interstitial fibrosis and the small late postoperative decrease of volume fraction of myofibrils, associated with a prosthesis-related slight left ventricular pressure increase, are at the origin of a persistent systolic overload at the myofibrillar level.

Quantitation of myocardial fibrosis and its relation to function in essential hypertension and hypertrophic cardiomyopathy

Myocardial interstitial fibrosis is an important microscopic feature of hypertrophic cardiomyopathy. To determine whether interstitial fibrosis of the myocardium in hypertrophic cardiomyopathy and essential hypertension differ in quality or quantity, and to determine whether fibrosis affects cardiac function directly, we measured the percentage of fibrosis in patients of both categories and compared the severity of fibrosis with several cardiac functions. Left and right ventricular endomyocardial biopsies were performed in 25 patients with essential hypertension and in 19 patients with hypertrophic cardiomyopathy. Interstitial fibrosis was classified into four different microscopic types, and the percentage of total and of each type was calculated using the point-counting method. Although the percentage of total fibrosis was similar between the two groups, the type of fibrosis was different. There was no correlation between the percentage of total fibrosis and the mean size of myocytes in either group. Although there was a significant correlation between the percentage of total fibrosis and the thickness of the interventricular septum in hypertrophic cardiomyopathy, such correlation was lacking in hypertension. There was no correlation between the percentage of total fibrosis and the ejection fraction, cardiac index, or left ventricular end-diastolic pressure in either group. We concluded that the amount of myocardial interstitial fibrosis in hypertrophic cardiomyopathy is no greater than that in essential hypertension, but the type of fibrosis is different. Furthermore, in subjects in whom the ejection fraction is normal or only slightly decreased, fibrosis does not influence global cardiac functions.

Dilated cardiomyopathy and myocarditis: natural history, etiology, clinical manifestations, and management

This monograph begins and ends with a statement of uncertainty regarding many aspects of dilated cardiomyopathy. Natural history studies identify patients with widely differing outcomes. A host of prognostic factors have emerged, yet it would appear that the major determinants of survival are as yet unrecognized. The diagnosis remains primarily one of exclusion, and management is largely nonspecific and supportive. The frequency of sudden cardiac death is well documented, but the ability to accurately identify patients at risk and the efficacy of antiarrhythmic therapy is unestablished. The emerging success of cardiac transplantation is a source of encouragement. The causes of dilated cardiomyopathy remain a source of intense investigation. Accumulating evidence (much of it circumstantial) does, however, implicate a viral etiology and perhaps altered function of the immunoregulatory system. However, the disparity between the severity of functional disturbance with the relative lack of histologic markers of cellular necrosis implies a disturbance at a cellular level. The etiology or etiologies remain elusive. Future investigation directed at fundamental aspects of cardiac cellular biology may provide the answers.

Myocardial performance and metabolism in non-ketotic, diabetic rat hearts: myocardial function and metabolism in vivo and in the isolated perfused heart under the influence of insulin and octanoate

The influence of a non-ketonic, chronically diabetic state (60 mg/kg streptozotocin) on cardiac function and metabolism was studied under in vivo conditions by inserting a Millar-tip catheter into the left ventricle and in the model of the isolated perfused heart. In vivo heart rate and maximal left ventricular systolic pressure were reduced after a diabetes duration of 4 and 12 weeks. The maximal rise and fall in left ventricular pressure progressively declined with the duration of diabetes. The reduced myocardial function was associated with a loss in ATP and adenine nucleotides. In the perfused heart of chronically diabetic rats, heart function was also impaired and could not be restored in vitro by perfusion with glucose and insulin. In the presence of octanoate--a substrate which can be metabolized independently from insulin--heart function of diabetic rats was improved, but remained lowered as compared to controls. Since the content of myocardial creatine phosphate was reduced in diabetic hearts perfused with octanoate, these findings indicate that the suppression of cardiac performance is not only a result of an impaired glucose metabolism, but of a more general defect in energy provision and utilization. In contrast to hearts of acutely diabetic, ketotic rats most often used, the rate of lipolysis of endogenous triglycerides and the contribution of fatty acids to energy production was low in the chronically diabetic state. Inhibition of fatty acid oxidation by an inhibitor of carnitine palmitoyltransferase (CPTI) did not restore the reduced responsiveness of diabetic hearts to insulin. Analysis of intracardiac metabolites revealed that in the perfused heart of chronically diabetic rats glucose-6-phosphate and citrate do not accumulate as in hearts of ketotic, diabetic rats. Therefore, the impaired glucose metabolism presumably reflects a reduced uptake of glucose rather than in inhibition of glycolysis as in hearts of ketotic, diabetic rats.

Comparative analysis of myocardial enzyme activities of the energy-supplying metabolism in patients with dilative cardiomyopathies and valve diseases

We determined representative enzyme activities of glycogenolysis (glycogen phosphorylase) glycolysis (d-glyceraldehyde-3-phosphate dehydrogenase, GAPDH), beta oxidation of free fatty acids (1-3-hydroxyacyl CoA dehydrogenase, HADH), citric acid cycle (citrate synthase, CS), lactate fermentation (lactate dehydrogenase LDH), and creatine phosphate metabolism (creatine kinase, CK) in left ventricular samples of 36 patients to investigate if the metabolic capacities of the energy-supplying pathways are differently affected in different heart diseases. There were 17 patients with mitral valve diseases (MVD), 8 patients with aortic valve diseases (AVD), and 11 patients who suffered from dilative cardiomyopathies (DCM). The main metabolic characteristic on the level of enzymatic organization in patients with DCM was an increased ratio of GAPDH/HADH activities and a decreased ratio of HADH/CS activities compared to the valve-diseased patients. This result indicates that the capacity of glucose oxidation is enhanced at the expense of fatty acid metabolism in patients with DCM. Furthermore, we determined significantly lower myocardial CK activities in this group of patients, most probably reflecting a diminished content of myofibrils. Citrate synthase activity was lowest in patients with AVD. Although we cannot rule out that the impaired left ventricular function is in part responsible for the shift of the capacities of the energy-supplying metabolism in patients with DCM, we favor the assumption that it is a specific feature of this myocardial disease.

Spontaneous hemodynamic improvement or stabilization and associated biopsy findings in patients with congestive cardiomyopathy

The hemodynamic courses of 56 patients with congestive cardiomyopathy (CCM) were investigated. Fourteen patients died within 24 months after diagnosis. The hemodynamic courses of the remaining 42 patients were investigated in subsequent examinations by determination of left ventricular ejection fraction (LVEF), mean pulmonary arterial pressure at maximal workload, and peak systolic pressure/end-systolic volume index. During the study interval of 32.2 +/- 20.0 months the conditions of 20 patients (48%) deteriorated, according to their hemodynamic status, and at least five of these died of terminal heart failure. Surprisingly, the conditions of 22 patients (52%) improved or stabilized. One of these died of leukemia. Seven patients in the latter group with initial LVEFs of 0.30 or less experienced an average increase from 0.22 to 0.51. Retrospectively consideration of age, alcohol intake, exercise capacity, and hemodynamic status were not helpful in predicting the course of the disease. In 38 patients endomyocardial biopsy samples could be obtained at the time of diagnosis. Reduced myofibril volume fraction (less than 60%) had prognostic significance for both hemodynamic deterioration and death (sensitivity 23/24 = 96%), while 14 of 15 patients whose conditions improved or stabilized had a myofibril volume fraction of 60% or more (specificity 14/15 or 93%, p less than .002). A relationship between hemodynamic status and the myofibril volume fraction could not be found. Individual patients with CCM differ significantly with respect to course of the disease. A distinct separation of the patients by means of morphologic criteria is possible. This makes it more likely that the pathogenesis of the disease is not unique.