Slide 1: Perkenalan

Slide 2: Aritmia adalah kelainan elektrofisiologi jantung dan terutama kelainan sistem konduksi jantung. Oleh karena itu, akan kita bahas sedikit mengenai sistem konduksi jantung.

Slide 3: Pada umumnya sel otot jantung yang mendapat stimulus dari luar, akan menjawab dengan timbulnya potensial aksi, yang mana terjadi depolarisasi yang disertai dengan kontraksi sel otot jantung, kemudian terjadi repolarisasi yang disertai dengan relaksasi. Potensial aksi dari satu sel otot jantung akan diteruskan ke arah sekitarnya melalui suatu peristiwa listrik yang disebut dengan konduksi.

Slide 4: Berlainan dengan sel-sel jantung biasa, dalam jantung terdapat kumpulan sel-sel jantung khusus yang mempunyai sifat dapat mencetuskan potensial aksi sendiri tanpa adanya stimulus dari luar. Sifat sel-sel ini disebut sifat automatisitas. Sel-sel ini terkumpul dalam suatu sistem yang disebut sistem konduksi jantung.

Slide 5: Sistem konduksi jantung terdiri dari: nodus SA (sinus), sistem konduksi intraatrial, nodus AV (nodus), berkas his, cabang berkas, fasikel dan serabut purkinje.

Slide 6: The Conduction System in a normal heart begins with the Sinus Node or SA Node. The Sinus Node (SA Node): Located in the upper right atrium. Known as the heart’s ‘Natural Pacemaker’. Produces resting rates between 60-100 BPM. (The SA Node has ‘automaticity’, which will be discussed later in this Module. It’s rate of automaticity is normally faster than all other parts of the heart, and therefore, dictates the rate at which the heart beats. This is known as “Sinus Rate”.)

Slide 7: The Atrioventricular Node or AV Node: Located between the Atrium and the Ventricles in the interatrial septum close to the tricuspid valve. Receives the impulse from the SA Node and delivers it through the Bundle of His (the forefront of the His-Purkinje network). Produces rates at 40-60 BPM if the SA Node fails to fire. Conduction through the AV Node is slow, allowing appropriate fill time for the ventricles prior to ventricular contraction. If the SA Node fails to deliver an impulse to the AV Node, the AV Junctional Tissue will deliver an impulse to the Bundle of His at rates between 40-60 BPM.

Slide 8: Bundle of His: Begins conduction to the ventricles. Together with the AV Node make up the AV Junctional Tissue. Junctional tissue produces rates between 40-60 BPM

Slide 9: Bundle Branches & Purkinje Fibers (make up the Purkinje Network): Together with the Purkinje Fibers make up the Ventricular Conduction System. Distribute the electrical impulse to the cardiac muscle allowing for depolarization (contraction) of the ventricle. Can deliver impulses at rates between 20-40 BPM, known as an ‘escape’ rhythm.

Slide 10: Berikut adalah bagaimana proses dari sistem konduksi jantung terekam dalam gambaran ekg. Initiation of the cardiac cycle normally begins with initiation of the impulse at the SA (sinoatrial) node.

Slide 11: After the SA node fires, the resulting depolarization wave passes through the right and left atria, which produces the P-wave on the surface EKG and stimulates atrial contraction.

Slide 12: Following activation of the atria, the impulse proceeds to the atrioventricular (AV) node, which is the only normal conduction pathway between the atria and the ventricles. The AV node slows impulse conduction, which allows time for the atria to contract and for blood to be pumped from the atria to the ventricles prior to ventricular contraction. Conduction time through the AV node accounts for most of the duration of the PR interval.

(Gelombang depolarisasi telah menyelesaikan perjalanannya melalui atrium menemui suatu sawar/ barrier yang disana tdpt AV node AV node memperlambat konduksi sampai menjadi lambat sekali (istirahat, berlangsung selama + 1/10 detik). Gunanya supaya atrium menyelesaikan kontraksinya sebelum ventrikel mulai berkontraksi sehingga memungkinkan atrium mengosongkan seluruh volume darahnya ke dalam ventrikel sebelum ventrikel berkontraksi.)

Just below the AV node, the impulse passes through the bundle of His. A small portion of the last part of the PR interval is represented by the conduction time through the bundle of His.

Slide 13: After the impulse passes through the bundle of His, it proceeds through the left and right bundle branches. A small portion of the last part of the PR interval is represented by the conduction time through the bundle branches.

Slide 14: Next the impulse passes through the Purkinje fibers (interlacing fibers of modified cardiac muscle). Conduction time through the Purkinje system is represented by a small portion of the last part of the PR interval.

Slide 15: The impulse passes quickly through the bundle of His, the left and right bundle branches, and the Purkinje fibers, leading to depolarization and contraction of the ventricles. The QRS complex on the EKG represents the depolarization of the ventricular muscle mass.

Slide 16: The Plateau Phase lasts up to several hundred milliseconds.

Slide 17: Repolarization of the ventricles generates a current in the body fluids and produces a T-wave. This takes place slowly, and generates a wide wave.

Slide 18: Here is another graphical view with each EKG wave represented with respect to the heart function associated with it.

Slide 20: Sel-sel miokard menunjukkan berbagai fase sifat responsif terhadap rangsang setelah sel-sel itu mengalami depolarisasi. Dari awal depolarisasi hingga awal repolarisasi sel-sel miokard tidak dapat menjawab stimulus baru yang kuat sekalipun. Periode ini disebut periode refrakter mutlak. Fase

selanjutnya hingga hampir akhir dari fase repolarisasi, sel-sel miokard dapat menjawab stimulus yang lebih kuat. Fase ini disebut periode refrakter mutlak.

Slide 21: