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Approximately 4-5% of sudden cardiac death victims who experienced
primary ventricular fibrillation and ventricular tachycardia (VT) had no apparent heart disease. Although in the absence
of heart disease or other known causal factors sudden cardiac death is exceptional, a definite cardiovascular etiology
was absent in up to 8% of pts who die suddenly1. These define special interest to the arrhythmias in the so-called
“normal heart”.
This investigation is focused on the subgroup of pts with idiopathic VA. We begin by identification the underlying
disease processes responsible for the development of rhythm disturbances. Emphasis is placed on the morphological
findings (anatomic substrate), identifiable risk factors for VA.
Since 1983 we evaluated 57 pts with high grade VA, sustained and nonsustained VT without evident heart disease
(mean age 23.5±8.48, 38 men). Most pts had no definable etiology for the cardiomyopathy process and were labeled
as having primary VA. All those pts had been grouped together for the purpose to stress the wide clinical spectrum of
VA. The investigation of the patients included routine ECG, Holter monitoring (Rozinn, USA), M- and B-mode
echocardiography, high-resolution ECG (HRECG, PREDICTOR 1, ART, USA), heart rate variability analysis (HRV, ART),
body surface multichannel mapping (Cardiag 128.1, Chech Rep), coronary- and ventriculography in doubtful cases,
electrophysiologic study (EPS). Our experience also included open heart surgery with fibrous endocardium resection
and guided by ventricular mapping, cryoablation of arrhythmogenic foci and biopsy investigation (1982-1993 yy.)2.
Radiofrequency ablation of arrhythmogenic foci and ICVD implantation were used as well in a later period.
According to the results of ECG, body surface mapping, EPS in 16 (28%) cases arrhythmia was originated from the left
ventricle (LV), in 36 pts (63%) – from right ventricle and in 5 (9%) cases arrhythmia involved the large macroreentrant
circuit including the bundle brunches. It was not possible to find the structural heart abnormalities except mitral valve
prolapse which did not exceed 2 mm and was not accompanied by mitral regurgitation. In 12 cases with right VT the
right ventriculography revealed pseudoaneurysms in right ventricular inflow and/or outflow tract. Right ventricular
mapping showed the same localization of arrhythmogenic foci. Finally, biopsy spacemen investigation in 14 pts carried
away during open heart surgery before cryoablation also found myocardial fatty infiltration even in young pts
(11-13 y.o.). Thus, the diagnosis or arrhythmogenic right ventricular dysplasia (ARVD) was confirmed although the
results of non-invasive methods could not reveal structural abnormality.
In 11 cases (mainly in pts with left VT) light microscopy biopsy investigation revealed focal fibrosis, degeneration of
myocytes and narrowed small vessels, which could be the result of myocarditis although no patient had appropriate
anamnesis. Electron microscopy showed dilation of sarcoplasmic reticulum and mitochondrial alterations in the
majority of cardiomyocytes. The hypercontraction of myofibrils and dehiscence of the intercalated discs were often
seen in arrhythmogenic areas.
The typical signs of different stages of apoptosis, which is not specific for well-differentiated heart tissue were found in
both arrhythmogenic and non-arrhythmogenic areas in three pts3.
We also evaluated heart rate variability and the results of high resolution ECG in patients without evident heart disease
but with VT. Late ventricular potentials were recorded in 3 (6%) patients. Thus, because of low sensitivity in this group
of pts the test has not been demonstrated to predict the risk of VT in this group of pts. Those findings suggested that in
that group demonstration of slow conduction during sinus rhythm is not a necessary prerequisite for a VA. It appeared
that in most pts the appropriate electrophysiologic substrate for VA could develop on a more dynamic basis. The rapid
changes in volume status, electrolyte shifts, intermittent hypoxia and catecholamine might potentiate the transient
development of the appropriate electrophysiologic milieu for arrhythmia initiation. We documented the predictable
change of abnormal heart rate variability in patients with idiopathic VA. The pts with idiopathic VT were in the same
age and gender group as normal persons (“control group”) (p>0.8 and p>0.4). The differences between mean heart
rate – RR duration and their standard deviations – SDNN were significantly lower than in control group, although we
could not find out the significant difference in frequency-domain indexes. The data was in accordance with the results
of L. Fei4. We also found out the strong reverse correlation between SDNN and the age of our pts which was much
more stronger than in different age normal persons without VT5: Pearson correlation coefficient was -0.81 in idiopathic
VT and -0.32 in normal group.
Thus, in so-called idiopathic VT some invasive methods and biopsy examinations could reveal structural hear
abnormality, including right ventricular dysplasia, chronic myocarditis and apoptosis. VA in pts without structural
abnormality might be critically dependent on autonomic regulation.
We started investigation and treatment of the pts with idiopathic VA in 1983 when the first patients were operated on
with preliminary ventricular mapping and cryoablation procedure. The longest follow-up with positive results in this
group exceeds 14 years. The positive results in this group were obtained in 73% of operated pts. The next period in
nonpharmacological approach included the era of radiofrequency ablation. For the moment our experience in this
field includes several successful cases although it is much less than it was done by some authors6. We also have some
cases treated by ICVD, although it was quiet rare experience in this group of pts.
Our decision regarding “how to treat idiopathic VA” is based now on the expression of symptoms and heart chamber
sizes (in cases with non-paroxysmal, so-called extrasystolic VT). When the pts have major symptoms they need an
active treatment. Radiofrequency ablation (RFA) of idiopathic VA is an effective technique with a high immediate
success5. The long-term follow-up of RFA and cryoablation procedure under direct vision should be compared
espacially in cases where ablation seems to be no efficient despite a repeat procedure.
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