Aetiology, diagnosis, investigation, and management of the cardiomyopathies

Beneficial effects of intramyocardial mesenchymal stem cells and VEGF165 plasmid injection in rats with furazolidone induced dilated cardiomyopathy

To explore the impact of myocardial injection of mesenchymal stem cells (MSCs) and specific recombinant human VEGF₁₆₅ (hVEGF₁₆₅) plasmid on collagen remodelling in rats with furazolidone induced dilated cardiomyopathy (DCM). DCM was induced by furazolidone (0.3 mg/bodyweight (g)/day per gavage for 8 weeks). Rats were then divided into four groups: (i) PBS group (n = 18): rats received equal volume myocardial PBS injection; (ii) MSCs group (n = 17): 100 μl culture medium containing 10⁵ MSCs were injected into four sites of left ventricular free wall (25 μl per site); (iii) GENE group (n = 18): pCMVen-MLC2v-EGFP-VEGF₁₆₅ plasmid [5 × 109 pfu (0.2 ml)] were injected into four sites of left ventricular free wall (0.05 ml per site)] and (iv) MSCs+GENE group (n = 17): rats received both myocardial MSCs and pCMVen-MLC2v-EGFP-VEGF₁₆₅ plasmid injections. After 4 weeks, cardiac function was evaluated by echocardiography. Myocardial mRNA expressions of type I, type III collagen and transforming growth factor (TGF)-β1 were detected by RT-PCR. The protein expression of hVEGF₁₆₅ was determined by Western blot. Myocardial protein expression of hVEGF₁₆₅ was demonstrated in GENE and MSCs+GENE groups. Cardiac function was improved in MSCs, GENE and MSCs+GENE groups. Collagen volume fraction was significantly reduced and myocardial TGF-β1 mRNA expression significantly down-regulated in both GENE and MSCs+GENE groups, collagen type I/III ratio reduction was more significant in MSCs+GENE group than in MSCs or GENE group. Myocardial MSCs and hVEGF₁₆₅ plasmid injection improves cardiac function possibly through down-regulating myocardial TGF-β1 expression and reducing the type I/III collagen ratio in this DCM rat model.

Mutations in Troponin that cause HCM, DCM AND RCM: what can we learn about thin filament function?

Troponin (Tn) is a critical regulator of muscle contraction in cardiac muscle. Mutations in Tn subunits are associated with hypertrophic, dilated and restrictive cardiomyopathies. Improved diagnosis of cardiomyopathies as well as intensive investigation of new mouse cardiomyopathy models has significantly enhanced this field of research. Recent investigations have showed that the physiological effects of Tn mutations associated with hypertrophic, dilated and restrictive cardiomyopathies are different. Impaired relaxation is a universal finding of most transgenic models of HCM, predicted directly from the significant changes in Ca(2+) sensitivity of force production. Mutations associated with HCM and RCM show increased Ca(2+) sensitivity of force production while mutations associated with DCM demonstrate decreased Ca(2+) sensitivity of force production. This review spotlights recent advances in our understanding on the role of Tn mutations on ATPase activity, maximal force development and heart function as well as the correlation between the locations of these Tn mutations within the thin filament and myofilament function.

Fulminant heart failure due to selenium deficiency cardiomyopathy (Keshan disease)

Selenium deficiency is a rare cause of cardiomyopathy that may be encountered by the forensic pathologist. Selenium deficiency is associated with a cardiomyopathy, myopathy and osteoarthropathy. In Asia and Africa, dietary selenium deficiency is associated with a cardiomyopathy known as Keshan disease and an osteoarthropathy called Kashin-Beck disease. Chronic selenium deficiency may also occur in individuals with malabsorption and long term selenium-deficient parenteral nutrition. Selenium deficiency causes myopathy as a result of the depletion of selenium-associated enzymes which protect cell membranes from damage by free radicals. We present a case of fulminant heart failure in a middle aged woman with a complex medical and surgical history including documented malabsorption and selenium deficiency. Pathological examination of the heart showed features consistent with Keshan disease.

Unconventional applications in pacemaker therapy

Since its inception, the principal application of permanent pacing has been for the correction of symptomatic bradycardia. During the past 3 decades, pacemaker therapy indications have evolved, through scientific research and through advances in technology, beyond conduction system disorders and sinus node dysfunction. This article presents recent progress in the application of permanent pacing in hypertrophic obstructive cardiomyopathy, dilated cardiomyopathy, paroxysmal atrial fibrillation, neurocardiogenic syncope, and in long-QT syndrome. In each clinical entity, certain pacing parameters are crucial for achieving the therapeutic goal. Advanced practice clinicians will encounter these patients in practice and are urged to recognize the therapeutic goal and optimal function of the device.