Acta Med Scand 1985; 217:27-32

Highly Refractile Myocardial Echoes in Familial Amyloidosis with Polyneuropat hy A Correlative Echoca rdiograp h ic and His to path o log ica i Study

PETER ERIKSSON, ANDERS ERIKSSON, CHRISTER BACKMAN, PER-AKE HOFER and BERT-OVE OLOFSSON From the Departments of Internal Medicine and Clinical Physiology and the Institutes of Forensic Medicine and Pathology, Universiry of Umed, Umed, Sweden

ABSTRACT. Eriksson P, Eriksson A, Backman C, Hofer P-A, Olofsson B-0. (Depart- ments of Internal Medicine and Clinical Physiology and Institutes of Forensic Medicine and Pathology, University of UmeA, Umeb, Sweden.) Highly refractile myocardial echoes in familial amyloidosis with polyneuropathy. Acta Med Scand 1985; 217: 27-32.

Two-dimensional echocardiography in systemic amyloidosis has in most cases shown highly refractile myocardial echoes. The morphological basis for this finding has so far been little examined. In the present study, echocardiographic examinations were per- formed in vitro on autopsied hearts from ten patients with familial amyloidosis with polyneuropathy (FAP). An ultrasonically visible needle was used to localize the abnormal echoes, and samples were taken for histological analysis of the region of the echocardio- graphic abnormality. Our results indicate that the highly refractile myocardial echoes in FAP are due to nodules composed of collagen and amyloid. Key words: amyloidosis, echocardiography, highly refractile echoes.

Familial amyloidosis with polyneuropathy (FAP) is one of the heredofamilial syndromes characterized by a systemic accumulation of amyloid, and with progressive polyneuro- pathy and often also autonomic neuropathy as prominent clinical features (1, 2). FAP has been reported from localized areas in many countries, including Portugal, Japan, England, and the USA (2). In Scandinavia, FAP has been diagnosed almost exclusively in the two northernmost counties of Sweden. Clinical and histopathological features of the Swedish variety of FAP have been reviewed previously (3).

Involvement of the heart is common in all forms of systemic amyloidosis, and important cardiovascular manifestations are congestive heart failure and heart rhythm disturbances (4). Recent reports on two-dimensional echocardiography in different forms of systemic amyloidosis, FAP included, have shown highly refractile myocardial echoes (HREs) in a large proportion of the patients (5-9).

In this investigation we have systematically correlated alterations in acoustic properties of the myocardium to morphological changes in ten FAP cases.

MATERIAL AND METHODS The hearts from ten patients with well documented FAP were included in this study. All patients had had clinical features characteristic of FAP: polyneuropathy affecting the legs more severely than the arms, gastrointestinal motility disturbances, urinary bladder dysfunction, and orthostatic hypoten- sion. The diagnosis was confirmed ante mortem by clinical and histopathological investigations, and post mortem by histological examinations of the autopsy material. The mean age at death was 72 years (range 43-89) and the mean duration of symptomatic polyneuropathy w a s 8 years (range 3-15). Two patients had valvular aortic stenosis. These two patients and an additional two had the symptoms and signs of congestive heart failure, and had been treated with diuretics. Four patients, including

Abbreviations: FAP = familial amyloidosis with polyneuropathy, HREs = highly refractile echoes.

28 P. Eriksson et al. Acta Med Scand 1985; 217

o M 0-HRE 0

Fig. 1 . Two-dimensional echocar- diographic image obtained in vitro. HRE = highly refractile myocardial echo, M = myocardium, N = pene-

a trating needle, T = tip of the needle.

those with aortic stenosis, had been treated with a pacemaker; three because of complete heart block and one because of atrial fibrillation with a slow ventricular response. None of the patients had a history of myocardial infarction or systemic hypertension and none had undergone echocardiographic examination.

Eleven control hearts were also examined. Six hearts were from subjects with no records of cardiovascular disease. The mean age of these subjects was 34 years (range 24-60). These hearts were included in order to obtain in vitro echocardiographic images of normal myocardium. Another five hearts from subjects with cardiac or cardiovascular diseases were also examined. Two had records of arterial hypertension, and one of previous myocardial infarction. One had calcific pericarditis (old tuberculosis) and one died from a ruptured aortic aneurysm. Their mean age was 64 years (range 54-73). These hearts were included to obtain in vitro images from hearts of older individuals, as fibrosis is known to increase with age (10) and may also be seen in various myocardial disorders.

All hearts were fixed and stored in neutral buffered formalin prior to the investigation. The in vitro examination of the hearts was carried out according to a technique described by

Bhandari and Nanda (9). Two-dimensional echocardiography was performed using a real-time wide angle (90") mechanical sector scanner with three revolving 3.0 MHz transducers (ATL Mark 111, Advanced Technology Laboratories). The heart specimens were suspended in a water bath at +22"C at a depth of 4 to 6 cm, and the transducer was placed at the water surface. In this way multiple echocardiographic views of the heart specimen were obtained, some simulating in vivo views. Both a 45 dB logarithmic and a linear grey scale curve were used. The amplitude and spatial distribution of echo signals reflected by the myocardium were evaluated visually. HREs were defined as echoes which could be visualized from two or more different projections or angulations and persisted at gain settings low enough to completely eliminate the echoes from the surrounding endo- and myocardium.

A 22-gauge ultrasonically visible metallic needle was advanced under echocardiographic control to recognize and penetrate areas with bright and/or highly refractile echoes about 4-8 cm from the water surface, a range with a good resolution. The contact between the tip of the needle and the myocardi- um was identified echocardiographically by the motion of the myocardial echoes and by the motion and altering form of the HREs. Specimens were dissected to contain the myocardium surrounding the tip of the needle to accurately correlate the echo pattern with the histopathological appearance. In this way several samples were obtained from the atrial and ventricular myocardium of the FAP and control hearts. The excised samples were dehydrated, embedded in paraffin and serially sectioned. Sections were alternately stained with alkaline Congo red and hematoxylin-eosin or according to the van Gieson-elastin method. On average, about 50 sections were retained from each sample.

RESULTS

In vitro two-dimensional echocardiography showed highly refractile myocardial echoes (HREs) in all ten FAP hearts. The HREs were localized single or multiple, distinct, and very bright echoes (Fig. 1). Their shape was rounded or somewhat irregular, and they were usually 2-5 mm in diameter. The HREs emerged more clearly when the linear grey scale curve was used instead of the 45 dB logarithmic grey scale curve. HREs were invariably found in the interventricular septum and left ventricular wall, and usually in the right

Acta Med Scand 1985; 217 Myocardial echoes in amyloidosis 29

Fig. 2. ( A ) micrograph of a myocardial sample showing the canal of the needle (arrow) and a nodule near the end of the canal. Hematoxylin- eosin X 4. ( B ) Higher magnification of a serial sec- tion showing amyloid as grey amorphous masses. Congo red x20.

ventricular wall and occasionally in the atria. The HREs in the interventricular septum seemed greater in number than in other parts of the myocardium, and they often appeared in clusters.

The hearts from the six controls with no history of cardiovascular disease showed a fine uniform mottled appearance of the myocardium, lined by echoes from the endo- and epicardium. After time-consuming search, solitary small (<3 mm) bright echoes were identified in three of these hearts. None of these echoes was highly refractile. At low gain settings, or when the linear grey scale curve was used, the myocardium appeared predomi- nantly echo-free. Four of the hearts of the five older controls showed single or few bright echoes in the interventricular septum and three also in the left ventricular free wall. These myocardial echoes were highly refractile in three cases. In two additional instances, highly refractile echoes were found to correspond to macroscopically visible calcifications in the coronary arteries. The patient with an old myocardial infarction also showed long bright aligned echoes in the interventricular septum and adjacent parts of the left ventricular posterior wall. These echoes corresponded to macroscopically visible fibrous scarring. No abnormal myocardial echoes were found in the heart with calcific pericarditis, but the myocardium, however, showed a diffusely increased echogenicity .

Histologically, it was possible to localize the morphological substratum for the HREs in all myocardial samples from the FAP hearts. The canal caused by the needle could easily be identified, and a defined nodule was situated at its end (Fig. 2). The diameter of the nodule was 1-3 mm, and four fifths of the nodules were very sharply demarcated. The nodules contained collagen, only a few fibroblasts and rarely a few myofibres. In addition, varying amounts of amyloid could be seen in the nodules, in two thirds constituting its major content. In one of the FAP hearts there were several vessels close to a nodule. Apart from this finding, there were no nodules or other major focal abnormalities in the sections except those indicated by the canal of the needle. As described previously (1 1,

30 P . Eriksson et al. Acta Med Scand 1985; 217

12), the myocardium in general exhibited diffuse interstitial amyloid infiltration. In addi- tion, there was sometimes an interstitial fibrosis.

In the hearts from subjects with no known cardiovascular diseases, the bright echoes corresponded to normal vascular structures. In some instances, no histopathological basis for the echoes could be identified. In these cases, the tip of the needle was very close to the endocardia1 border, and the echoes seemed to originate from endomyocardial inter- faces. In the hearts from cases with cardiovascular diseases, the HREs corresponded to vascular structures in three fourths, and perivascular fibrosis was usually seen. In one fourth, the HREs were related to fibrous nodules with no adjacent vessels. Furthermore, a few bright echoes seemed to correspond to endomyocardial interfaces, with no focal histopathological changes. A diffuse fibrosis without focal abnormalities was found in the heart with pericarditis. None of the hearts of the controls showed amyloid deposits.

DISCUSSION

Echocardiographic findings indicating cardiac involvement in patients with systemic amy- loidosis include increased thickness of the interventricular septum and the left and right ventricular walls, pericardial effusion and thickened cardiac valves (5-8, 13-15). With the two-dimensional technique, a peculiar hyperrefractile myocardial appearance has been observed in a large proportion of the patients, and this has been considered to be a characteristic feature of cardiac amyloidosis (5-8, cf. 9). The underlying histopathological basis for the HREs has, however, not yet been definitely settled. Only Bhandari and Nanda (9) have attended to this problem previously. They found in two cases of cardiac amyloidosis examined in vitro that HREs corresponded to amyloid deposits without concomitant fibrosis or calcification.

In our in vitro study, all ten hearts from patients with FAP showed HREs, and all had abundant amyloid within the myocardium. We found that HREs correlated to nodules containing amyloid and collagen in varying proportions.

It is well known that the high collagen content of fibrous tissue results in increased ultrasonic backscatter (16), and amyloid might have the same property. Our results do not allow separation of the respective importance of amyloid and collagen as the cause of HREs in FAP. The finding of Bhandari and Nanda of amyloid without concomitant fibrosis, however, indicates that amyloid per se might cause HREs. The reason for the discrepancy between our histopathological findings in FAP and those of Bhandari and Nanda is unclear. The type of amyloidosis was not stated in their study, but different types of amyloidosis with different amyloid proteins have probably been studied (17).

The acoustic properties of the myocardium may have changed in vitro due to factors such as fixation and storing. However, there was a good agreement between the in vitro findings and our previous observations in a clinical echocardiographic study on patients with FAP (8). Furthermore, all control hearts had been handled in the same way, and the six cases with no cardiovascular disease showed a uniform anechoic appearance with a few bright echoes.

In normal hearts, most bright echoes represent ordinary vessels, and occasionally echoes seem to emerge from tissue interfaces. HREs in non-amyloidotic hearts also correspond to vascular structures, usually with perivascular fibrosis. In addition, fibrous nodules may produce HREs, as well as calcific deposits in coronary arteries.

The echocardiographic appearance of the myocardium in a wide variety of heart disorders has recently been reported by Bhandari and Nanda (9) who used the same kind of echocardiographic equipment and technique to identify and localize HREs. Their material included seven patients with amyloidosis, of whom all showed HREs, but HREs

Acta Med Scand 1985; 217

were also observed in other conditions such as Pompe’s disease, left heart hypoplastic syndrome, hypertrophic cardiomyopathy, hemochromatosis, chronic renal failure and ventricular hypertrophy. In the noninfiltrative disorders, HREs were shown to result from fibrosis. Consequently, HREs seem to be an unspecific finding, which must be related to the underlying disorder. In adult patients, however, diffuse and extensive involvement of all walls of one or both ventricles with HREs was noted only in amyloidosis (4 of 7 patients) and, rarely, in hypertrophic cardiomyopathy.

According to a study by Lendrum et al. (18), the degree of “fibrosis” may indicate the age of the amyloid. In a light-microscopic study on renal amyloidosis, these authors state that the amyloid goes through an ageing process and ends up in a hyalin material that stains like collagen and for which they suggest the name pseudo-collagen. On the other hand, the possibility of the amyloid being deposited in fibrous nodules already present must also be considered (19).

Our study indicates that cardiac involvement in FAP can be accurately assessed non- invasively by two-dimensional echocardiography. The results may also be valid for other forms of systemic amyloidosis, and the method might also be of value in the diagnosis of other infiltrative myocardial disorders.

Myocardial echoes in amyloidosis 3 1

ACKNOWLEDGEMENTS This study was supported by grants from the University of Umel, the Swedish National Association against Heart and Chest Diseases and Karl-Oskar Hansson and Arner Foundations.

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Received Jan. 27. 1984.

Correspondence: Dr P. Eriksson, Department of Internal Medicine, University Hospital, S-90185 Urneft. Sweden.