| Abstract | Uvod: Idiopatska ventrikulska tahikardija iz istisnog sustava desnog ventrikula najĉešća
je ventrikulska smetnja ritma u bolesnika bez strukturne bolesti srca. Mehanizam
nastanka tahikardije smatra se potaknuta (trigerirana) aktivnost kao posljedica
katekolaminsko zavisne kasne depolarizacije koja nastaje zbog prekomjerne stimulacije
cikliĉnog AMP i prekomjernog porasta intracelularnog kalcija koji se oscilatorno otpušta
iz sarkoplazmatskog retikuluma. Molekularnom genetikom dokazano je da se radi o
somatskoj mutaciji G-proteina, koji zbog supstitucije jedne aminokiseline u lancu gubi
svojstva i inhibitorni uĉinak na razinu staniĉnog cAMP, nakon ĉega slijedi njegov porast
i povišena razina intracelularnog kalcija i pojaĉano djelovanje Na+- Ca2+ izmenjivaĉa na
membrani miokardne stanice - pojaĉana struja je dovoljna da dolazi do kasne
depolarizacije i trigerirane aktivnosti. U kliniĉkoj praksi postoje dva razliĉita tipa
idiopatske ventrikulske tahikardije - paroksizmalni trajni tip i repetitivni tip, oni nemaju
jasne granice i prelaze jedan u drugoga. Tahikardija je rezistentna na antiaritmiĉku
terapiju ili su potrebne vrlo velike doze, što je tada popraćeno nuspojavama. Zbog toga
se tahikardija primarno lijeĉi radiofrekventom ablacijom, koja je uspješna i omogućuje
trajno izljeĉenje aritmije. Radiofrekventna ablacija aritmije klasiĉno se obavlja poslije
elektrofiziološkog ispitivanja i mapiranja inducirane trajne tahikardije. No, trajnu
idiopatsku tahikardiju teško je postići zbog fokalnog porijekla i nemogućnosti indukcije
standardno programiranom stimulacijom, pa su potrebni dugotrajni postupci s
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inkremetalnim dozama izoproterenola. No, gotovo svi bolesnici s epizodama idiopatske
ventrikulske tahikardije iz istisnog sustava imaju i brojne izolirane ventrikulske ektopije
morfologije poput kliniĉke aritmije. U ovome radu dokazujem da se taj tip aritmije moţe
uspješno ablirati i u sinusnom ritmu mapiranjem ventrikulskih kompleksa iste
morfologije i praćenjem odreĊenih markera uspjeha kao što su brzi repetitivni odgovor
tijekom aplikacije RF i što dulje lokalno aktivacijsko vrijeme na ablacijskom kateteru
prije ablacije.
Metoda: U ovome radu testirali smo skupinu od 66 bolesnika s RVO-VT u dobi od 50
± 14 g. koji su lijeĉeni nemedikamentno RF-ablacijom aritmije. Bolesnike smo
randomizirali izmeĊu dvije skupine. U prvoj skupini s 33 bolesnika 51,45 ± 15 g. RFablacija
bila je obavljena novim pristupom u sinusnom ritmu, a u drugoj s 33 bolesnika
50,24 ± 14 g., klasiĉno za vrijeme trajne RVO-VT. Bolnike smo nakon elektrofiziološke
procedure pratili 24 mjeseca. Uz promatranje uspješnosti ablacije definirali smo nove
parametre uspjeha abalacije u sinusnom ritmu, kao što je ciklus brzog repetitivnog
odgovora i lokalno aktivacijsko vrijeme koji trebaju biti prisutni pri RF-ablaciji novim
pristupom.
Rezultati: U prvoj skupini akutni uspjeh ablacije bio je 97,0%, a u drugoj 78,7%, P =
0,05, dok je recidivnost u smislu supkliniĉke ventrikulske ektopije unutar 24 mjeseci
bila u prvoj skupini 18,2%, a u drugoj skupinio 57%, P = 0,005. Vrijeme trajanja
procedure bilo je u prvoj skupini 70 ± 16 min., a u drugoj 120,5 ± 29 min. P < 0,001
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jednako je bila diferenca o potrebi broja aplikacija RF do akutnog uspjeha u prvoj bilo je
potrebno 13,4 ± 12, dok je u drugi skupini bilo 21,6 ± 15, P = 0.03. Uz praćenje uspjeha
ablacije definirali smo parametre koji koreliraju s akutnim i kroniĉnim uspjehom. U
skupini s akutnim uspjehom bez relapsa ciklus brzog repetitivnog odgovora bio je 293,7
± 54 msec, dok je u skupini s relapsom bio 332,3 ± 71 msec, P = 0.001. RF-ablacija
novom metodom omogućila je i stabilnije mapiranje izvora RVO-VT. U skupini s
akutnim uspjehom bez relapsa lokalno vrijeme aktivacije prije ablacije bilo je 31,3 ± 15
msec, a u skupini s relapsom bilo je 24,3 ± 12 msec, P = 0.002. Većina subkliniĉkih
replapsa lijeĉena je malim dozama beta-blokatora ili verepamila, dok je reablacija bila
potrebna samo u dvoje bolesnika. Ni u jednoj skupini bolesnika nije bilo ozbiljnih
komplikacija lijeĉenja.
Zaključak: Nemedikamentna terapija RVO-VT u smislu RF-ablacije vrlo je uspješna i
pouzdana metoda s dobrim akutnim i trajnim uspjehom bez popratnih komplikacija.
Novi pristup RF-ablaciji obavljen u sinusnom ritmu bez potrebe za indukcijom i
odrţavanjem tahikardije za vreme RF-ablacije, pokazao se boljim kako u smislu boljeg
akutnog kao trajnog uspijeha tako i u bitnom skraćenju trajanja zahvata. Novi pristup
omogućio je da RF-ablacija postane primarna terapija RVO-VT i bude primijenjena i u
lijeĉenju bolesnika sa samo RVO-VT ektopijom. |
| Abstract (english) | Introduction: Idiopathic right ventricular tachycardia is the most frequent type of
ventricular arrhythmia in patients without structural heart disease. Pathophysiology is
trigged activity as a consequence cathecholaminic dependent afterdepolarization due to
hyperstimulation of cAMP which leads to increase in intracellular calcium and its
oscillatory release from sarcoplasmic reticulum. Molecular genetic mechanism is
somatic mutation of G protein which is due to substitution of one amino acid in protein
chain ineffective and loses its inhibitory effect on intracellular cAMP concentration.
Increased intracellular calcium concentration follows increased Na+- Ca2+ exchanger
activity on cellular membrane which generates potential enough high to trigger delayed
depolarization an triggered activation. Two distinct types of idiopathic right ventricular
tachycardia are known in clinical practice paroxysmal sustained and repetitive which
overlaps and could change from one to another. This type of tachycardia is resistant to
many antiarhythmic medication or high dosage is needed bearing serious side effects.
Tachycardia is primarily treated by radiofrequency ablation. Ablation is carried out
during electrophysiology procedure in sustained ventricular tachycardia which is
sometimes rather difficult to induce and sustained so besides programmed stimulation
isoproterenol infusion is needed. Almost all of patients with idiopathic right ventricular
outflow tachycardia have also frequent ventricular ectopy bearing the same morphology
as tachycardia. In this clinical study I am presenting successful radiofrequency ablation
of arithmogenic focus of tachycardia by mapping ventricular ectopy with the same
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morphology as I have been approving some markers of successful ablation as are fast
repetitive response during ablation and local activation time before ablation.
Method: We have treated 66 patients due to right ventricular outflow tract tachycardia
50 ± 14 years. Patients were randomized between two groups, in the first 33 patients
51,45 ± 15 years a new approach of radiofrequency ablation was carried out during
sinus rhythm, in the second group 33 patients 50,24 ± 14 years were treated by
conventional approach during sustained ventricucular tachycardia. All of patients were
had follow up in next 24 months after ablation procedure. Besides screening an acute
and sustained success of ablation in both groups the markers of success as a cycle length
of fast repetitive response and local activation time were tested as a markers of success.
Results: In the first group acute success was 97,0% and in the second one 78,7%, P =
0,05, relapse rate as a subclinical ectopy in 24 months after ablation was in the first
group 18,2% and in the second 57%, P = 0,005. Procedure length in the first group was
70 ± 16 min. and in the second procedure duration was 120,5 ± 29 min. P < 0,001
respectively. The number of radiofrequency application was 13,4 ± 12 in the firs and
21,6 ± 15, P = 0.03 in the second group. Markers of an acute as sustained success were
cycle length of fast repetitive response 293,7 ± 54 msec in patients without relapse and
acute success and 332,3 ± 71 msec, P = 0.001 in patients with relapse. In patients treated
without relapse the local activation time was 31,3 ± 15 msec and in patients with relapse
24,3 ± 12 msec, P = 0.002 regardless of way of ablation. Most subclinical relapses were
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treated by low doze antyarhythmic medication as beta blockers and verapamil with
success the need for reablation was present in only two cases. There were no serious
complication observer in any group.
Conclusion: Nonmedical treatment of right ventricular tachycardia by radiofrequency
ablation is a very successful and safe procedure with a high acute and a long lasting
success without serious complications. The results of the new approach of treatment by
radiofrequency ablation in sinus rhythm without need for sustained ventricular
tachycardia induction was approved to be better and bears higher acute and long lasting
success rate and drastically shorter procedure time. Due to shorter procedure time this
procedure could be regarded as a primary treatment in patients with right ventricular
outflow tract tachycardia and could be also useful in treatment of patients with frequent
ventricular ectopy originated from right ventricular outflow tract. |
