Vol 61, No 4 (2002)
Original article
Published online: 2002-08-29
The arrangement of muscle fibres in the region of the subthebesian fossa in the aspect of atrial flutter
Folia Morphol 2002;61(4):283-289.
Abstract
The typical atrial flutter is the most common supraventricular tachycardia with
reentrant circuit. This tachyarrythmia is based on macroreentry wave going around
established anatomic landmarks. The reentry in the inferior right atrial wall passes
through narrow isthmus, which is the goal for ablative therapy. The isthmus
area is bordered anteriorly by the tricuspid valve and posteriorly by the inferior
vena cava, coronary sinus, and eustachian ridge. Near to this area we can find
anatomical structure, which can be very important during arising, perpetuation
and curing of atrial flutter. The concavity, so-called subthebesian fossa [15], is on
the way of typical atrial flutters’ reentrant circuit.
Regarding the facts mentioned above we decided to examine the morphology and the arrangement of the muscle fibres in this fossa. Research was conducted on material consisting of 70 human hearts of both sexes from the age of 34 to 72 years. 50 hearts came from patients whose death was not cardiologic in origin. 20 hearts came from humans in whose common atrial flutter was confirmed. We observed the arrangement of muscle fibres in the area of subthebesian fossa. Besides we measured the size and deepness of the subthebesian fossa in both groups of hearts.
We found that regular arrangement of muscle fibres within subthebesian fossa was present in 23 healthy human hearts (46%) and 7 cases (35%) of hearts with atrial flutter. The irregular arrangement of muscle fibres was observed in 27 hearts (54%) of control group and 13 hearts (65%) with dysrrhythmia. The thickness of the right atrial wall within the subthebesian fossa was very thin in 8 normal hearts (16%) and in 5 dysrrhythmic hearts (25%). The sizes of examined structure were variable in both groups of hearts, and are presented in the table. It seems that the subthebesian concavity can be the substrate for reentrant circuit during atrial flutter, and there could be such special arrangement of muscle fibres, which allows for microreentrant circuit to arise in this area.
Regarding the facts mentioned above we decided to examine the morphology and the arrangement of the muscle fibres in this fossa. Research was conducted on material consisting of 70 human hearts of both sexes from the age of 34 to 72 years. 50 hearts came from patients whose death was not cardiologic in origin. 20 hearts came from humans in whose common atrial flutter was confirmed. We observed the arrangement of muscle fibres in the area of subthebesian fossa. Besides we measured the size and deepness of the subthebesian fossa in both groups of hearts.
We found that regular arrangement of muscle fibres within subthebesian fossa was present in 23 healthy human hearts (46%) and 7 cases (35%) of hearts with atrial flutter. The irregular arrangement of muscle fibres was observed in 27 hearts (54%) of control group and 13 hearts (65%) with dysrrhythmia. The thickness of the right atrial wall within the subthebesian fossa was very thin in 8 normal hearts (16%) and in 5 dysrrhythmic hearts (25%). The sizes of examined structure were variable in both groups of hearts, and are presented in the table. It seems that the subthebesian concavity can be the substrate for reentrant circuit during atrial flutter, and there could be such special arrangement of muscle fibres, which allows for microreentrant circuit to arise in this area.
Keywords: typical atrial fluttermacroreentry wavesubthebesian fossa
