Spiral Wave Attachment to Millimeter-Sized Obstacles

Abstract

Background-Functional reentry in the heart takes the form of spiral waves. Drifting spiral waves can become pinned to anatomic obstacles and thus attain stability and persistence. Lidocaine is an antiarrhythmic agent commonly used to treat ventricular tachycardia clinically. We examined the ability of small obstacles to anchor spiral waves and the effect of lidocaine on their attachment. Methods and Results-Spiral waves were electrically induced in confluent monolayers of cultured, neonatal rat cardiomyocytes. Small, circular anatomic obstacles (0.6 to 2.6 mm in diameter) were situated in the center of the monolayers to provide an anchoring site. Eighty reentry episodes consisting of at least 4 revolutions were studied. In 36 episodes, the spiral wave attached to the obstacle and became stationary and sustained, with a shorter reentry cycle length and higher rate. Spiral waves could attach to obstacles as small as 0.6 mm, with a likelihood for attachment that increased with obstacle size. After attachment, both conduction velocity of the wave-front tip and wavelength near the obstacle adapted from their pre-reentry values and increased linearly with obstacle size. In contrast, reentry cycle length did not correlate significantly with obstacle size. Addition of lidocaine 90 mol/L depressed conduction velocity, increased reentry cycle length, and caused attached spiral waves to become quasiattached to the obstacle or terminate. Conclusions-Anchored spiral waves exhibit properties of both unattached spiral waves and anatomic reentry. Their behavior may be representative of functional reentry dynamics in cardiac tissue, particularly in the setting of monomorphic tachyarrhythmias.

Region of slowed conduction acts as core for spiral wave reentry in cardiac cell monolayers

“…After 7 min, the chamber was sealed and the dye was washed out. Action potentials (AP) were optically mapped using a custom-built contact fluorescence imaging system as previously described (18,25).…”

Spiral Waves, Obstacles and Cardiac Arrhythmias

“…Therefore, the main objective of this work is to present a numerical study of the interaction of spiral waves with obstacles and to show the existence of different transitions due to the presence of obstacles. By considering non-excitable and partially excitable obstacles we will show that obstacles cannot only stabilize the dynamics as shown in (Ikeda et al, 1997;Kim et al, 1999;Lim et al, 2006), but also, they can act as destabilizers. In both cases and by different mechanisms, the obstacle might act as a switch between two arrhythmic regimes, in which one is less dangerous than the other.…”

“…Examples of partially excitable obstacles are scar tissue (Starobin et al, 1996) or ionic heterogeneities (Starobin et al, 1996;Tusscher & Panfilov, 2002;Valderrábano et al, 2000), whereas examples of non excitable obstacles are arteries (Valderrábano et al, 2000) or the natural orifices in the atria (Azene et al, 2001). It has been observed that an obstacle in cardiac tissue might act as a stabilizer of spiral wave dynamics (Davidenko et al, 1992;Ikeda et al, 1997;Kim et al, 1999;Lim et al, 2006;Pertsov et al, 1993;Valderrábano et al, 2000), as it provides a transition between meandering spiral waves (Ikeda et al, 1997) or multiple spiral waves (Shajahan et al, 2007;Valderrábano et al, 2000) into a simple rotation spiral, which is attached to the obstacle. This 17 www.intechopen.com transition is clinically important because as it has been shown, fibrillation like activity changes to a tachycardia regime (Kim et al, 1999).…”

Approche multi-échelle appliqué à la modélisation de l’activité électrique du coeur

“…Par la suite, la réentrée sera pérennisée si le temps nécessaire à la circulation du front est supé-rieur à la période réfractaire partout le long du circuit. On a montré qu'un obstacle, de diamètre aussi petit que 0,6 mm, pouvait ancrer la réentrée 4 dans des cultures de tissu -bien que la dimension minimale fût dix fois plus grande dans l'oreillette du chien [11,12]. Toute modification du tissu qui augmente la probabilité de la formation d'un bloc local ou qui diminue la vitesse de propagation autour d'un obstacle sera favorable au déclenchement et au maintien de réentrées.…”