Therapeutic management of dilated cardiomyopathy

The therapeutic approach to dilated cardiomyopathy (DCM) still remains nonspecific and symptomatic, since no specific etiology is identified. Nevertheless, the recent introduction of angiotensin converting enzyme (ACE) inhibitors and beta-blockers greatly improved the treatment of DCM. The poor prognosis of patients with DCM encourages maximal aggressive attempts to prevent progression of ventricular dysfunction rather than to wait for treatable symptoms. To achieve this goal, vasodilators, particularly ACE inhibitors, now appear to be essential for the treatment of DCM. Digitalis is added unless contraindicated by adverse effects. Diuretics should be used only to relieve congestive symptoms. In the presence of sinus tachycardia or ventricular arrhythmias, beta-blockers are the next choice in our practice. When congestive symptoms or low output state are not controlled with vasodilators, diuretics, and digitalis, inotropic agents are indicated, with or without mechanical assist devices. For severely ill patients unresponsive to maximal medical management, heart transplantation is needed.

A deletion of mitochondrial DNA in murine doxorubicin-induced cardiotoxicity

A deletion of about 4 kb has been determined in the mutated mitochondrial DNA (mtDNA) in cardiomyocytes with chronic doxorubicin (DOX)-induced cardiotoxicity in mouse. The incidence of the mtDNA deletion increased with the dosage and with the duration of the DOX administration. Coenzyme Q10 administration prevented the mtDNA deletion and decreased the thiobarbituric acid reactive substance content in the heart mitochondria, suggesting some free radical involvement in this mtDNA deletion. This mtDNA deletion may be involved in cardiomyopathy, which is known to be dosage-dependently induced by DOX administration.

A missense mutation of cardiac beta-myosin heavy chain gene linked to familial hypertrophic cardiomyopathy in affected Japanese families

A novel missense mutation of the cardiac beta-myosin heavy chain gene was detected in five unrelated Japanese patients and their affected family members with hypertrophic cardiomyopathy (HCM) by using the polymerase chain reaction (PCR)-DNA conformation polymorphism (DCP) analysis. Sequencing analysis revealed an A to G transition at codon 778 leading to replacement of the Asp residue, which is adjacent to the interaction sites of myosin heavy chain (MHC) with actin and is a conserved amino acid residue in various MHC across species, to the Gly residue. Linkage study of the mutation and two dinucleotides repeat markers of the cardiac beta-MHC gene in three affected families showed that the mutation was on the same haplotype of the cardiac beta-MHC gene and linked to HCM. These observations strongly suggest that the 778Asp to Gly mutation is the cause of HCM in these affected individuals.

Cyclic flow variations in a conscious dog model of coronary artery stenosis and endothelial injury correlate with acute ischemic heart disease syndromes in humans

OBJECTIVES

The purpose of this study was to test the hypothesis that episodes of cyclic flow variations (CFVs) in conscious dogs with coronary stenoses and endothelial injury correlate with acute ischemic heart disease syndromes in humans.

BACKGROUND

Although the canine model with CFVs has proved to be a useful model of coronary thrombosis, whether CFVs progress to these syndromes has not been clearly described.

METHODS

Cyclic flow variations were produced by an external constrictor placed at the site of the left anterior descending coronary artery with injured endothelium. Blood flow in this artery and 24-h Holter electrocardiogram (ECG) were recorded during the 1st 5 postoperative days.

RESULTS

Of 41 dogs that underwent the initial operative procedure successfully, 29 developed an episode of CFVs. In five dogs in which CFVs persisted throughout the monitoring period, the left anterior descending coronary artery flow decreased until day 3 and thereafter increased through day 5. Transient coronary occlusion during CFVs induced ST segment changes that returned to baseline after reflow. In 12 dogs, CFVs progressed to persistent coronary occlusion, and histologic examination revealed thrombus formation at the stenotic site and evidence of myocardial infarction. Four of these 12 dogs died suddenly of ventricular arrhythmias during persistent coronary occlusion; another 5 dogs died of reperfusion arrhythmias during CFVs with no evidence of myocardial infarction.

CONCLUSIONS

Conscious dogs with CFVs closely correlated with clinical acute ischemic heart disease syndromes, suggesting them to be a useful model for investigating the complex mechanisms of cellular interactions in the pathogenesis of these syndromes.

[A study of myocardial disorders in an autopsy case of mitochondrial encephalomyopathy]

We report an autopsy case of a 19 year-old man with MELAS (mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes) a subgroup of mitochondrial encephalomyopathy presenting cardiomyopathy. He had repeatedly suffered from transient unconsciousness, hemiplegia, hemianopsia and convulsion attacks since the age of 9, and he died of severe congestive heart failure. In laboratory findings, blood lactate and pyruvate were markedly increased. Skeletal muscle biopsy demonstrated numerously scattered ragged-red fibers with modified Gomori's trichrome staining. Enzymatic activities of the mitochondrial respiratory chain showed a marked decrease of NADH cytochrome c reductase (complex I). In postmortem examination, the heart was 310g in weight and had right ventricular dilatation. Microscopically, degenerated and scattered myocardial cells (ragged-red fibers), interstitial edema and microvascular hyperplasia were demonstrated in the myocardium. Under the electron microscope, abnormal mitochondria proliferated and myofibrils were unusually sparse. Immunohistochemical studies with specific antibodies against the mitochondrial electron transfer enzyme subunits revealed a reduction of immunoreactive materials for complex I in the myocardium. These results suggested the relationship of myocardial disorders and decreased activity of complex I in electron transfer enzymes in this patient.

Alterations in beta-adrenergic receptor density and cyclic-AMP level in the myocardium of rats chronically treated with alcohol

An impaired function of the myocardial beta-adrenergic receptor system has been reported in patients with end-stage heart failure and this impairment has been postulated to be a factor in further deterioration of cardiac contractile function. As ventricular dysfunction is often associated with prolonged alcohol abuse, we investigated whether or not chronic administration of ethanol could induce alterations in the beta-adrenergic receptor adenylate-cyclase system in rats. Male Wistar rats of 8 weeks of age received 33% ethanol in drinking water for 3 months. As compared with control rats drinking water, the ethanol-treated rats showed weight loss and an increase in the heart/body weight ratio. Chronic ethanol increased myocardial contents of norepinephrine and epinephrine, possibly resulting from sympathoadrenal activation. The beta-adrenergic receptor density (Bmax) of the myocardial membrane was significantly decreased in the ethanol-treated rats (27.7 +/- 9.9 vs 39.0 +/- 6.0 fmol/mg protein, p < 0.01), while the affinity (Kd) did not differ between the two groups. The myocardial content of cyclic-AMP was also reduced in the ethanol rats (865 +/- 59 vs 1055 +/- 83 pmol/g w.w., p < 0.01). These observations indicate that chronic ethanol administration depresses the function of the beta-adrenergic receptor adenylate-cyclase system. The decreased beta-adrenergic receptor density was partly attributed to down-regulation due to increased sympathetic stimulation. This impaired function may contribute to the cardiac contractile dysfunction observed in chronic alcoholics.

Evaluation of the intramembrane particle count in biopsied myocardium from patients with idiopathic cardiomyopathy

To clarify the abnormalities of myocardial membrane structure in cardiomyopathy, the density of intramembranous particles (IMP) of mitochondria, sarcoplasmic reticulum and sarcolemma, and the number of caveolar necks was evaluated by freeze-fracture morphology. The subjects consisted of 17 patients with hypertrophic cardiomyopathy (HCM), 6 patients with dilated cardiomyopathy (DCM), and 7 patients as controls. The results showed that the numbers of IMPs on the membrane faces of mitochondria, sarcoplasmic reticulum and sarcolemma were significantly decreased in HCM and DCM, and that they were decreased more markedly in DCM than in HCM. The number of caveolar necks was significantly decreased in DCM. Thus, the decreased numbers of IMPs on myocardial membranes and the decrease in caveolar necks may be important characteristics resulting from abnormal myocardial membrane metabolism in cardiomyopathies, HCM and DCM.

Adult coronary artery disease probably due to childhood Kawasaki disease

We have surveyed adult survivors of childhood Kawasaki disease (KD) who had coronary artery disease that could be ascribed to KD. In response to questionnaires sent to cardiologists throughout Japan, 21 patients (17 men, 4 women, aged 20-63 years) with coronary lesions and a definite (2) or suspected (19) history of KD were reported. 5 patients had presented with acute myocardial infarction, 6 previous myocardial infarction, 9 angina pectoris, and 1 dilated cardiomyopathy. 16 patients had obstructions in two or more coronary arteries. 3 had died and 18 were alive with serious sequelae (mitral regurgitation, arrhythmias, congestive heart failure). Childhood KD should be included in the differential diagnosis of coronary artery disease in young adults.

Point mutations in mitochondrial DNA in patients with hypertrophic cardiomyopathy

Recent advances suggest that mutations in nuclear DNA are involved in the etiology of autosomal dominant hypertrophic cardiomyopathy. Mitochondria have their own DNA, and mutations in mitochondrial DNA have been shown to contribute to the genesis of various diseases. In this study, we developed rapid sequencing methods with the use of a fluorescence-based sequencing system and analyzed total mitochondrial DNA of seven patients with nonautosomal dominant hypertrophic cardiomyopathy. Multiple point mutations were observed in all patients with hypertrophic cardiomyopathy, although some of them were common among the subjects examined and the others are unique to each subject. Point mutations in transfer RNA genes were observed in five of the seven patients, and point mutations that replaced conserved amino acids were also observed. These mutations may result in the impairment of mitochondrial function. According to these results, mutations in mitochondrial DNA may contribute to the genesis of some cases of nonautosomal dominant hypertrophic cardiomyopathy, and our methods may be useful for the detection of point mutations in mitochondrial DNA.

Novel missense mutation in cardiac beta myosin heavy chain gene found in a Japanese patient with hypertrophic cardiomyopathy

We have analyzed the exon 9, 13, 14, 15, and 16 of cardiac beta myosin heavy chain gene in 96 Japanese patients with hypertrophic cardiomyopathy by using PCR-DNA conformation polymorphism analysis. The analysis revealed a sequence variation of the exon 16 in one patient. The sequence variation of a G to C transversion with replacement of Asn by Lys at the codon 615 was confirmed by sequencing and by dot-blot hybridization with an allele-specific oligonucleotide probe. Because the missense mutation was found at the residue conserved through birds to humans, this mutation was suggested to be a cause of hypertrophic cardiomyopathy in the patient. This is the first report of a mutant cardiac beta myosin heavy chain gene in the Japanese population.

Postoperative erythroderma after cardiac operations. The possible role of depressed cell-mediated immunity

Erythroderma as a manifestation of graft-versus-host disease after cardiac operations with blood transfusion may occur more frequently in Japan than in other countries. We have seen this problem in five patients who, after heart operations, died with symptoms and signs characteristic of graft-versus-host disease: cutaneous eruption, fever, diarrhea, leukopenia associated with agranulocytosis, and liver dysfunction. In the three patients seen most recently, skin biopsy showed findings similar to those of graft-versus-host disease after bone marrow transplantation. In addition, immunologic investigation showed remarkable differences in the findings in these patients and in those who did not have a graft-versus-host disease-like syndrome after cardiac operations. In particular, interleukin-2 production in response to mitogen stimulation was markedly diminished after operation in our patients, and the ratio of OKT4+ cells to OKT8+ cells in peripheral blood was low, reflecting increased numbers of OKT8+ cells after the occurrence of symptoms. The results raise the possibility that transient depression of cellular immunity after cardiac operations with blood transfusion may contribute to the occurrence of postoperative acute graft-versus-host disease.

Therapeutic effect of oral dipyridamole on myocardial perfusion and cardiac performance in patients with hypertrophic cardiomyopathy

Recent studies have indicated that myocardial ischemia could occur and could play an important role in the pathophysiology of patients with hypertrophic cardiomyopathy (HCM). We therefore investigated whether or not dipyridamole--a selective coronary vasodilating agent--could favorably modify myocardial perfusion and the clinical manifestations in 20 patients with HCM (19 nonobstructive and one mildly obstructive) with an average age of 50 years. Oral dipyridamole, 150 mg/day for 2 weeks, prevented reversible perfusion defects initially observed in six patients on baseline exercise thallium-201 (201TI) scintigraphy and significantly increased the 201TI clearance (40 +/- 13% to 44 +/- 12%), while one patient developed new reversible perfusion defects. There were significant increases in echocardiographic fractional shortening and treadmill exercise time and reductions in cardiac size and supraventricular arrhythmias with dipyridamole therapy. These observations suggest that coronary vasodilation with dipyridamole may improve myocardial perfusion and cardiac function in patients with HCM.

Beneficial antiarrhythmic effect of beta-blockade in patients with dilated cardiomyopathy

Antiarrhythmic effects of beta-blockade (BB) in patients with dilated cardiomyopathy were compared with those of various antiarrhythmic agents using ambulatory Holter monitoring. The BB therapy effectively suppressed ventricular extrasystoles (VEs) in 85% of patients, as evidenced by improvement in Lown's grade or a reduction in the number of the highest grade VEs greater than 50%. In contrast, conventional antiarrhythmic agents, except flecainaid and amiodarone, were poorly effective in suppressing VEs. BB therapy gradually increased left ventricular fractional shortening (16 +/- 6% to 22 +/- 12%) and improved 12-month survival rates as compared with those receiving conventional therapy (93 vs 69%). This antiarrhythmic potency seemed to be an additional therapeutic efficacy of BB in the management of patients with dilated cardiomyopathy, which frequently associated with serious VEs.

Vitamin E deficiency has a pathological role in myocytolysis in cardiomyopathic Syrian hamster (BIO14.6)

This study revealed the occurrence of vitamin E deficiency in the myocardium of 60-day-old Syrian cardiomyopathic hamsters (BIO14.6), and that this deficiency might be related to the increase in lipid peroxide. Vitamin E administration for ten days effectively restored creatininekinase activity and decreased the lipid peroxide content in the myocardium, returning these to normal control levels (F1b). These results indicate that vitamin E deficiency, possibly combined with oxidative stress in the early cardiomyopathic stage plays an important role in initiating the pathogenesis of myocardial lesions.

[Cardiac mast cells in myocardial diseases]

Mast cells play a role in inflammation and immunological reactions. Cardiac mast cells with their granules are demonstrated easily by toluidine blue staining. We evaluated cardiac mast cells in endomyocardial biopsy specimens in patients with acute myocarditis (n = 17), idiopathic dilated cardiomyopathy (n = 17), idiopathic hypertrophic cardiomyopathy (n = 17) and control subjects (n = 12). Cardiac mast cells increase to an extreme degree in patients with acute myocarditis (2.4 counts/mm2) and increase relatively in patients with idiopathic dilated cardiomyopathy (1.4 counts/mm2). Patients with idiopathic hypertrophic cardiomyopathy (0.4 counts/mm2) were similar to control subjects (0.5 counts/mm2). Cardiac mast cells increased in accord with the severity of cellular infiltration and of interstitial fibrosis except for some cases with very severe fibrosis. In the acute myocarditis group, cardiac mast cells were well demonstrated in the early stage of the illness. But degranulations of mast cells did not give us any significant information in this study. Evaluation of cardiac mast cells will provide us with a new aspect in studying primary myocardial diseases.

New noninvasive assessment of regional left ventricular function by digital subtraction angiography without the use of contrast medium

We have developed a new noninvasive method to evaluate regional left ventricular (LV) function by digital subtraction angiography (DSA) without the use of contrast medium. DSA images of the left ventricle with and without contrast medium were obtained from 35 patients with anterior myocardial infarction (MI) and from 35 control subjects. Using an image-processing computer, regional LV time-density curves were constructed for one cardiac cycle. Regional LV time-density curves obtained from DSA without the use of contrast medium presented a pattern similar to those from intravenous DSA. The amplitude of regional LV time-density curves in patients with MI decreased along with increasing severity of regional wall motion abnormality assessed by conventional left ventriculography. In attempting semi-quantitative evaluation by DSA without the use of contrast medium, the regional wall motion index (RWI) in the 6 segments of the left ventricle was calculated by normalizing segmental density changes to the maximal segmental density changes. When compared with control subjects, patients with MI have significantly lower RWIs in the anterolateral and apical regions. RWI showed a good correlation with the regional ejection fraction (REF) obtained from intravenous contrast DSA (r = 0.83). RWI decreased with increasing severity of regional wall motion abnormality by qualitative analysis in conventional left ventriculography, being consistent with REF. The diagnostic accuracy of RWI therefore seemed to be comparable to that of REF derived from intravenous contrast DSA. These results indicate that computerized analysis of DSA without the use of contrast medium is a valuable noninvasive method for semi-quantitative assessment of regional LV function.

[Quantitative analysis of myocardial fibrosis in myocardial biopsies--a comparison between computer analysis and point counting method]

To select an appropriate method to analyze quantitatively myocardial fibrosis in myocardial biopsies, two methods, the computer analysis and the point-counting method observed at magnifications of x200 and x400, were compared. Our targeted points of examination were the accuracy and reproducibility of these methods. Twenty patients (10 with dilated cardiomyopathy and 10 with hypertrophic cardiomyopathy) were randomly selected, and the percent area of myocardial fibrosis in myocardial biopsies obtained from the right ventricular septum was measured by both the computer analysis and the point-counting method. Two observers measured the same area twice on the different days, independently. In the area of analysis, the endocardium was excluded to avoid the observer's bias. By comparing the data obtained from two observers, it was shown that the point-counting method tended to give a larger mean value and standard deviation than the computer analysis method, but that the latter indicated better reproducibility than the former. Our result showed that the degree of myocardial fibrosis varied according to methods of analysis and observer's experiences. It is recommended that the comparison of myocardial fibrosis should be made only when the methods of analysis of fibrosis are identical.

Norepinephrine inhibits human natural killer cell activity in vitro

The effect of norepinephrine on human NK cell activity was investigated using a flow cytometry assay. NK cell activity was found to be inhibited by direct addition of norepinephrine to lymphocyte/target cell mixtures in a dose-dependent fashion. This inhibitory effect of norepinephrine was blocked by propranolol but not by atenolol. The results suggest that norepinephrine has a negative influence on NK cell activity and that the effect of norepinephrine is mediated via beta 2-adrenoceptors.

Physical training in patients with valvular heart disease after surgery

The necessity, the methodology and clinical benefit of physical training were evaluated in 85 patients with valvular heart surgery. In 21 patients who had undergone the exercise stress test before surgery, corrective valvular surgery increased maximal oxygen uptake (max.VO2) from 15.4 before to 18.9 ml/min/kg, while 11 (52%) of them failed to increase exercise capacity over 5 METs. Of the total 85 patients, 41 (58%) again showed reduced exercise capacity in the initial postoperative stress test, suggesting that a return to work might be difficult without rehabilitation in these patients. We then compared two training programs: program A of short duration and frequent exercise and program B of longer duration and less frequent exercise, both using a bicycle exercise set at an intensity of 70% of the max.VO2. Both programs similarly increased max.VO2, while patients preferred program A, suggesting that exercise of longer duration could not be tolerated because of deconditioning. Program A was then prescribed to 62 patients, and it increased max.VO2 from 18.2 to 20.7 ml/min/kg after 4 weeks training without any complication. In 9 patients who served as controls undergoing no physical training, no spontaneous improvement in exercise capacity was observed. Of the 76 patients who received either program A or B, 28 patients failed to increase the max.VO2 by 10% or more. These patients presented atrial fibrillation, a cardiothoracic ratio greater than or equal to 60% or exercise-induced ST depression more frequently, suggesting that residual cardiac dysfunction might inhibit the training effects.(ABSTRACT TRUNCATED AT 250 WORDS)