The cardiomyopathy in Friedreich's ataxia: isotopic ventriculography and myocardial imaging with thallium-201

May age onset be relevant in the occurrence of left ventricular hypertrophy in Friedreich's ataxia?

BACKGROUND

Although heart involvement has been widely reported in Friedreich's ataxia (FA), which is the most prevalent of the spino-cerebellar degenerative diseases, the reason that cardiac abnormalities develop has not been yet established.

HYPOTHESIS

The investigation was undertaken to study the prevalence and characteristics of cardiac abnormalities in patients with FA and to evaluate whether the presence of left ventricular hypertrophy could be predicted.

METHODS

In all, 75 patients with FA and 16 patients with late onset FA (LOFA) disease were investigated for cardiac abnormalities using noninvasive methods.

RESULTS

A significant (p < 0.01) difference in the age onset (9.8 +/- 3.9 years) was found in 31 of the 75 patients with FA (41%) who showed left ventricular hypertrophy (LVH) at echocardiographic examination compared with the remaining 44 patients with FA without LVH (12.6 +/- 4.3 years). Moreover, none of the 16 patients with LOFA (age onset 26.5 +/- 4.2 years) showed abnormalities at echocardiographic examination. A significant (p < 0.01) concordance in the familial distribution of hypertrophy was also found.

CONCLUSION

These data suggest that the earlier the disease develops the more frequently LVH occurs.

Coronary flow reserve

The ability of the coronary circulation to autoregulate is essential for the heart to respond to metabolic demands. Several alterations in function may limit maximal coronary perfusion including atherosclerosis, structural abnormalities of small coronary vessels, extravascular compressive forces, thrombosis, abnormal endothelial regulatory function, and the effect of abnormal myocardium on the coronary circulation. Coronary flow reserve is a unifying concept that examines the limitation in myocardial perfusion that certain disease states impose. At present, even with state-of-the-art technology, the measurement of coronary flow reserve is difficult in routine clinical situations. As the ability to measure regional myocardial perfusion improves, coronary flow reserve may gain more widespread clinical use with perhaps as yet undiscovered therapeutic implications.

The spectrum of diseases of small coronary arteries and their physiologic consequences

There is a wide spectrum of abnormalities in the structure of small coronary arteries, with regard both to the portion of the arterial wall involved and to the histologic nature of the disease. A fuller understanding of this spectrum permits more useful interpretation of the pathophysiologic basis for the functional consequences of small coronary artery disease. In this review based on personal observations during examination of more than 1,000 human hearts postmortem there is initially a description of the wide variety of structural abnormalities, then a discussion of the functional consequences of these abnormalities and finally a section of general comments to weave together the structural and functional discussion in the context of clinical evaluation of patients who have small coronary artery disease. Future studies should apply fractal analysis and quantitative topology, methods that lend themselves particularly well to an investigation of the progressively smaller branching of the human coronary tree.

Biventricular function in Friedreich's ataxia: a radionuclide angiographic study

The systolic and diastolic function of both ventricles was assessed by radionuclide angiography in 21 patients with Friedreich's ataxia and hypertrophic cardiomyopathy. The indices of systolic function of the two ventricles and those of diastolic function of the right ventricle were generally normal. But in patients with Friedreich's ataxia the time to peak filling rate divided by the diastolic time of the left ventricle was significantly larger than normal. The increase correlated with the heart rate (r = 0.79) and this suggests an alteration in the timing of ventricle filling that is more evident at high heart rates. Movement of the left ventricle was little impaired; however, in 48% of the patients with Friedreich's ataxia the right ventricle showed evidence of hypokinetic segments. Because there is a tendency for congestive heart failure to develop in patients with Friedreich's ataxia, this hypokinesis of the right ventricle should be monitored at follow up.

Coronary disease, cardioneuropathy, and conduction system abnormalities in the cardiomyopathy of Friedreich's ataxia

Abnormalities of the heart are a frequent and possibly ubiquitous problem in patients with Friedreich's ataxia, but their pathogenesis is unclear. Postmortem findings are reported from the hearts of three patients with Friedreich's ataxia who died of congestive heart failure and atrial arrhythmias. Particular attention was paid to the following: the large and small coronary arteries, the nerves and ganglia, the conduction system, and the histological and cellular features of the cardiomyopathy. There were pleomorphic nuclei and focal fibrosis and degeneration throughout each heart including the conduction system. There were distinctive abnormalities of both large and small coronary arteries, and focal degeneration of nerves and ganglia. These observations suggest a mosaic concept for the pathogenesis for the cardiomyopathy of Friedreich's ataxia that involves the interplay of molecular faults, cardiomyopathy, cardioneuropathy, and coronary disease.