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This work was supported by grants from the National
Research Council targeted project "Prevention and control disease factors";
subproject "Pathology arrhythmias and sudden cardiac death".
Cardiac repolarization disorders, under the common label of long QT interval, can be
subdivided into a genetic, familial form as a syndrome, and into an apparently acquired
one, as a symptom1.
The genetic form has been recently recognized to depend from threefold different types
of gene mutations attended, respectively, by differential responses to Na+
channel blockade and increases in heart rate2,3 and has
been further enriched by a newer contribution4.
However, beyond and besides long QT syndrome(s), a wider group of "acquired"
repolarization derangements is presently focusing much interest from specialists5.
In this domain, a major drawback is hindering research, namely that of very
controversial electrocardiographic criteria for determining the diagnostic measure of the
QT interval, particularly in tachycardiac subjects6. To
this, one should always add the persisting ignorance about any possible histopathological
background for this major life-threatening arrhythmogenic disease, despite the abundance
of cases lamentably at disposal for post-mortem examination.
With the exception of the by now possible genetic investigations, the only
clinicopathological clue to a structural examination on the victims of long QT lethal
tachyarrhythmia, seems to stand upon the knowledge that the triggering of harmful torsade
de pointes is, mostly, hyper-sympathetic in nature1.
Thereby, particular attention has been paid, by few specialized pathologists, to
changes of the heart's innervation, the left stellate ganglion first of all7; indeed, this can become available from a number of
living patients with familial or acquired forms, operated upon. However, both ante- and
post-mortem left stellate ganglion controls, as well as rare observations of the intrinsic
and extrinsic cardiac plexuses, failed to exhibit any pathognomonic abnormality. Anyway,
since the investigation of the autonomic innervation of the heart still stands as the most
suitable one in pathology of long QT, whatever its origin, the present authors resorted to
operate "higher up" by the microscopical investigation on the hitherto neglected
sympathetic "center". In a case of apparently "acquired" long QT (a
male patient of 56 years succumbed to sudden cardiac death), who had been operated for
prostethic substitution of an aneurysmic abdominal aorta two years before and showed sinus
tachycardia (120 beat/min) with long QT interval, histology showed chronic
pachymeningitis-radiculitis of the thoracic spinal cord involving the roots of the spinal
nerves and ganglion. The most interesting histopathological degenerative features
configurated a marked tigrolysis of the sympathetic neuronal column at the T3-T4 level
(Fig. 1); this change was localized within the intermediolateral grey horn, while the
nearby neurons were normal. No cardiac changes were found. Discussion can arise from the
fact that some specialists are not prone to calculate the QT interval in tachycardiac
subjects; which is entirely contradicted by other investigations, led by the Finnish group
of Karjalainen5,6. Indeed the herein proposed
correlation between the diseased sympathetic center in the thoracic spinal cord and a
prolongation of QT interval, was based upon the Karjalainen correlation-method6.
 
Fig. 1: (56 yr male) Thoracic spinal cord (T3-T4): framed
between the grey anterior (ANT) and posterior (POST) horn, the intermediolateral neuronal
column of the sympathetic cardiovascular respiratory "center". Bielschowski x
12.
Be this as it may, our observations are the first in the literature and, having been
made on the autonomic center for sympathetic cardiac reflexogenic modulation, are likely
to be particularly critical to an inherent disorder.
And this in comparison with the hitherto alleged correlations based on discrete
abnormalities of the widespread heart's innervation periphery.
Thereby, our findings can prompt a novel orientative suggestion to pathologist
interested in the anatomoclinical study of long QT, in general: which also seems to be
timely enough, since Karjalainen himself lately drew special attention to the fact that a
prolonged QT interval (obviously calculated according to the method of his own), would
represent a major risk factor in an unpredictable number of men with heart disease5.
Fig. 2: Chronic pachymeningitis (right) extending as a per-endocardiculitis (left) of
the spinal cord metamera T3-T4: hematox - eosin x 200 and x 20.
Fig. 3: On the left: spinal cord T3-T4 sympathetic neurons
showing marked tigrolysis (see normal one on the right); below the ECG with sinus
tachycardia and long QT interval (corrected by Karyolainen method) Klüver-Barrera x 900.
Acknowledgements
The authors thank Gioacchina Randazzo for the secretarial support.
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