Kuyini, kungani kubalulekile
Ivelidi ye-atrioventricular (AV) iyisici esiyinhloko senqubo kagesi yenhliziyo. Ilawula ukuhamba komfutho wenhliziyo kagesi kusuka ku-atria kuya kwi-ventricles.
Kuyini i-AV Node?
I-AV node "inkinobho" encane yamaseli akhethekile (cishe ngo-3 no-5 mm ububanzi) eseduze nasenkabeni yenhliziyo, ngakwesokudla kwe-septum ye-atrial ekuhlanganiseni kwe-atria nama-ventricles.
Umsebenzi walo ukusiza ukuxhumanisa ukukhishwa kwe-atria nama-ventricles ngokuphendula isignali kagesi senhliziyo.
Yini i-AV Node?
I-noode ye-AV ilawula ukuhamba kwesignali kagesi senhliziyo kusuka ku-atria kuya kuma-ventricles.
Ngemuva kokucindezela kagesi kukhishwa yi- node ye-sinus , isakazeka ngaphesheya kwe-atria, okwenza ukuba i-atria ibethe. I-noode ye-AV ke "iqoqa" ukuthi umfutho wegesi futhi, emva kokulibaziseka okufutshane, ivumela ukuthi idlulisele ezingeni le-ventricles.
Ukubaluleka komtholampilo we-AV Node
I-noode evamile ye-AV ibalulekile ekusebenzeni kahle kwenhliziyo. Ukulibaziseka okusheshayo emfuthweni kagesi obangelwa i-AV node iqinisa ukusebenza kwenhliziyo. Ukulibaziseka kuvumela ukuthi i-atria iqede ukushaya, ukuze ama-ventricle agcwale ngokuphelele igazi, ngaphambi kokuba ama-ventricles aqale ukushaya.
Ngaphezu kwalokho, ngokungafani nakwezinye izingxenye zesistimu kagesi yenhliziyo, ngokuphindaphindiwe i-AV node ishukunyiswa yimigudu kagesi, kancane kancane iqhuba ugesi.
Lesi sici - esibizwa ngokuthi "ukuqhutshwa kokunciphisa" - kubaluleke kakhulu nge (isibonelo) ukufubha kwe-atrial , lapho i-AV node ibhalwa khona ngamakhulu kagesi kagesi ngomzuzu. Ukuqhutshwa kokunciphisa ukuvimbela iningi lalezo zifiso ekufinyeleleni ama-ventricles, futhi kugcina izinga lenhliziyo lingabi nengozi kakhulu.
I-AV node ihlinzekwa ngokucebile yi- vagus nererve . Ukunyuka kwethebula le-vagus nerve (njengokungathi kungashukunyiswa ngomkhondo we- Valsalva ) kungavimbela ukuhamba kwe-electrical impulse ngokusebenzisa i-AV node. Lo mkhuba uyasiza ekunqandeni izinhlobo eziningi ze -tachycardia (SVT) ezingaphezulu.
Abanye abantu bazalwa ngezindlela ezimbili ezihlukile zombane ngokusebenzisa i-AV node, engabenza bajwayele ukuhlela okubizwa ngokuthi i-AV nodal reentrant tachycardia, noma i-AVNRT. Ungafunda lapha nge-AVNRT .
Izifo ze-AV node zingabangela ukubambezeleka, noma ibhuloho eliyingxenye noma eliphelele, ekudlulisweni kwezimfutho zikagesi kusukela ku-atria kuya kwi-ventricles - isimo esaziwa ngokuthi "i- heart block ".
Ukulibaziseka ekuqhutshweni nge-node ye-AV kubonakala ku- ECG njengokwenyuka kwe "PR interval." (Isikhathi se-PR silinganisela isikhathi esiphakathi kokuvinjelwa kwama-atriyali nokuvinjelwa kwe-ventricular.) Isikhathi sesikhathi eside se-PR, esikhiqizwa ukulibaziseka ekuqhubeni kwe-AV, kubizwa ngokuthi "i-block yokuqala AV block".
Uma ukuqhutshwa kwe-AV nodal kungasheshi ngokwanele, i-heart block ingagcina. Nge "block block AV" yesibili "izimpendulo ezithile zivinjelwe ekufinyeleleni ama-ventricles. With "block yesithathu AV block" zonke izimo zivinjelwe.
Ngezinye izikhathi i-AV nodal block iphawuleka ngokwanele ukukhiqiza i- bradycardia eqinile, nokufakwa kwe- pacemaker kungadingeka. Kodwa-ke, i-heart block ebangelwa ukungasebenzi komzimba we-AV ngokuvamile ihlobene nezidakamizwa (ezifana ne- beta blockers noma i- calcium channel blockers ), noma ngezinkinga zezokwelapha ezandisa i-vagal verve ithoni (njenge-nausea nokuhlanza), futhi ingahlala iphathwa njalo ngaphandle kokuba ukuze usebenzise i-pacemaker.
Noma kunjalo, imbangela eyodwa ye-AV nodal block ingadinga i-pacemaker engapheli, okungukuthi, i- myocardial infarction (ukushaya kwenhliziyo) . I-node ye-AV ithola igazi layo kusukela kumthambo we-AV nodal, okuyi-90% wabantu igatsha le- artery coronary efanele .
Ngakho-ke i-AV nodal block ngenxa yesifo senhliziyo isivame ukubonwa ngokuhlaselwa kwenhliziyo ye-coronary artery. Ngenhlanhla, ngisho nakulezi zimo i-AV node ngokuvamile ibuyisela ngokwanele ezinsukwini ezimbalwa ukwenza i-pacemaker ingadingekile.
Imithombo:
Epstein AE, DiMarco JP, Ellenbogen KA, et al. I-ACC / AHA / HRS 2008 Izinkombandlela zokwelashwa okusekelwe ngeDivaysi ye-Cardiac Rhythm Okungajwayelekile: umbiko we-American College of Cardiology / American Heart Association Task Force on Guidelines Practice (IKomidi Yokubhala Ukubuyekeza I-ACC / AHA / NASPE 2002 Isiqondiso Sokuqondiswa Kwokufakwa of Pacemakers Cardiac and Antiarrhythmia Devices): athuthukiswe ngokubambisana ne-American Association for Thoracic Surgery kanye neNhlangano Yezintatheli Zezintambo. Ukujikeleza ngo-2008; 117: e350.