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ID naloge: 140 Letnik: 2003 Predmet: interna medicina
UCINKOVITOST PREDDVORNO-PREKATNE IN SINHRONE PREKATNE ELEKTROSTIMULACIJE SRCA PRI BOLNIKIH S STALNIMI SRCNIMI SPODBUJEVALNIKI
Avtor: Luka Lipar, David Žižek
Mentor: doc. dr. Igor Zupan
IZHODIŠCE: Srcni spodbujevalnik (pacemaker) omogoca srcu, da ujame lastni ritem. Stimulacija lahko poteka v desnem preddvoru in/ali prekatu. Sekvencna preddvorno-prekatna stimulacija (DDD) vkljucuje stimulacijo in zaznavanje v preddvoru in prekatu, poleg tega pa je možen tudi dvojni odgovor - z inhibicijo ali stimulacijo. Sinhrona prekatna stimulacija (VDD) omogoca zaznavanje v preddvoru in prekatu ter dvojni odgovor, vendar poteka stimulacija samo v prekatu. V Sloveniji je v primerjavi z Evropo izrazit delež vsajenih spodbujevalnikov tipa VDD.
NAMEN: Sinhrona prekatna stimulacija (VDD) je alternativa sekvencno preddvorno-prekatni stimulaciji (DDD) pri bolnikih s preddvorno-prekatnim blokom in normalno funkcijo sinusnega vozla. Pri spodbujevalnikih tipa VDD igra kljucno vlogo zaznavanje v preddvoru, ki pa zaradi lebdece elektrode ni tako zanesljivo kot pri tipu DDD. V primeru slabega zaznavanja preddvora stimulacija ni vec fiziološka, ampak asinhrona. Posledica odsotne preddvorno-prekatne usklajenosti je spodbujevalniški sindrom.
HIPOTEZA: Pri spodbujevalnikih tipa VDD in DDD smo primerjali zaznavanje preddvorov, prag prekatne stimulacije, preddvorno-prekatno usklajenost ter impedanco stimulacije in kvaliteto življenja. Preveriti smo želeli hipotezo, da med spodbujevalniki tipa VDD in DDD obstajajo razlike, ki so pomembne glede zanesljivosti elektrostimulacije kot tudi glede hemodinamske ucinkovitosti.
METODE: V prospektivni raziskavo smo vkljucili 96 preiskovancev, katerim so leta 2000 vsadili srcni spodbujevalnik tipa VDD ali DDD. S programatorjem smo neposredno izmerili prag zaznavanja v preddvoru in prag prekatne stimulacije. Izmed sumarnih meritev smo odcitali vrednost preddvorno-prekatne usklajenosti in impedanco prekatne elektrode. Vrednosti navedenih parametrov ob vsaditvi smo poiskali v vložnem kartonu Klinicnega oddelka za kardiovaskularno kirurgijo. Preiskovancem smo zastavili tudi sklop vprašanj, na podlagi katerih so podali subjektivno oceno kvalitete življenja. Rezultate smo statisticno obdelali s Studentovim testom t za neodvisne vzorce ali testom t za dva neodvisna vzorca po Mann-Whitney-u.
REZULTATI: Zaznavanje v preddvoru je bilo ob vsaditvi pri spodbujevalnikih tipa VDD statisticno znacilno nižje kot pri tipu DDD (p<0,001). Enako razmerje smo ugotovili tudi ob kontroli. Prag prekatne stimulacije je bil ob vsaditvi pri spodbujevalnikih tipa VDD statisticno znacilno nižji kot pri tipu DDD (p<0,02). Ob kontroli med pragom stimulacije pri tipu VDD in DDD ni bilo statisticne razlike (p=0,49). Pri preiskovancih s spodbujevalnikom tipa VDD je bila preddvorno-prekatna usklajenost statisticno znacilno nižja kot pri tipu DDD (p<0,001). Razlika v vrednostih impedance ob vsaditvi in ob kontroli je bila pri preiskovancih s spodbujevalnikom tipa VDD znacilno nižja od enake razlike pri tipu DDD (p<0,001). Povprecna ocena kvalitete življenja je bila pri preiskovancih s spodbujevalnikom tipa VDD prakticno enaka kot pri tipu DDD (p=0,96).
ZAKLJUCKI: Rezultati delno potrjujejo našo hipotezo. VDD stimulacija je sicer zanesljiva in varna, vendar hemodinamsko manj ugodna kot DDD. Bolniki oba nacina stimulacije dobro prenašajo in ne navajajo pomembnejših razlik. Potrebno je izboljšati tehniko vsaditve preddvorne elektrode, predvsem glede na položaj preddvornega dipola.
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[Abstract / English version]
UCINKOVITOST PREDDVORNO-PREKATNE IN SINHRONE PREKATNE ELEKTROSTIMULACIJE SRCA PRI BOLNIKIH S STALNIMI SRCNIMI SPODBUJEVALNIKI
Author: Luka Lipar, David Žižek
Mentor: doc. dr. Igor Zupan
BACKGROUND: Cardiac pacemaker is a device that enables the heart to beat with its own rhythm. Right atrium and/or ventricle can be stimulated. DDD pacing system refers to dual chamber pacing and sensing with double choice of answer - inhibition or stimulation of atrium or ventricle. VDD stands for a single chamber pacing and dual chamber sensing pacing system. There is a distinctive share of implanted VDD pacemaker systems in Slovenia in comparison to other European countries.
AIM: VDD pacing system is an alternative to DDD pacing system in patients with atrioventricular (AV) block and normal sinus node function. Critical point in VDD pacing system is atrial sensing which is not as reliable as with DDD pacing system due to a floating sensing electrode. In case of inappropriate atrial sensing the stimulation is no longer physiologic and asynchrony occurs. Loss of AV synchrony leads to pacemaker syndrome.
HYPOTHESIS: We compared atrial sensing, ventricular stimulation threshold, AV synchrony, ventricular lead impedance and quality of life in patients with VDD and DDD pacing systems. We assume that there are differences concerning electro stimulation and hemodynamic support between VDD and DDD pacing systems.
METHODS: Ninety-six patients with implanted VDD or DDD pacing system in year 2000 were enrolled prospectively into our study. Using the programator we directly measured sensing threshold in atrium and pacing threshold in ventricle. Among measured data we also evaluated AV synchrony and ventricular lead impedance. We obtained the values of noted parameters at the time of implantation from archive files at Clinical department for Cardiovascular Surgery. Patients were also interviewed with a set of questions upon which they assessed their quality of life. Obtained data was statistically analyzed with Student's t-test for independent samples or Mann-Whitney t-test for two independent samples.
RESULTS: Atrial sensing was significantly lower with VDD pacing system compared to DDD system at implantation and at present evaluation (p<0,001). Ventricular pacing threshold was significantly lower with VDD pacing system compared to DDD system at implantation (p<0,02). At present evaluation there was no significant difference between VDD and DDD pacing systems (p=0,49). AV synchrony was statistically lower with VDD pacing system compared to DDD system (p<0,001). Difference between the values of ventricular lead impedance at implantation and at present evaluation was significantly lower with VDD pacing system compared to DDD system (p<0,001). Average quality of life did not differ significantly between the VDD and DDD pacing systems (p=0,96).
CONCLUSIONS: Results are partly in accordance with our hypothesis. VDD pacing systems are reliable and safe concerning electro stimulation. However, hemodynamic support is better with DDD pacing systems. Patients assessed both pacing systems as very good and did not elucidate significant differences. The technique of implantation of VDD systems should be improved to achieve optimal position of atrial electrode in realtion to atrial dipole.
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