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Figure 6 Schematic representation of atrial tachycardias mapped in the right atrium (RA), depicting macro–re-entrant circuits, focal tachycardias and passive activation of the RA during left atrial tachycardias. The patient numbers are identified, as are the surgical approaches to the mitral valve. The projections include right lateral (RL), right anterior oblique (RAO), anteroposterior (AP) and posteroanterior (PA) views. Gray areas indicate zones of low amplitude potentials. Also identified are the crista terminalis (CT) and coronary sinus (CS). Blue tags represent double potentials, and pink tags are fractionated potentials. Sites marked with x indicate concealed entrainment with a postpacing interval 10 ms longer than the atrial tachycardia cycle length. Green lines represent the direction of activation, and green stars denote the origin of focal tachycardias. During left atrial tachycardias, activation of the RA occurs via the low septal RA or Bachmann’s bundle. IVC = inferior vena cava; SVC = superior vena cava; TV = tricuspid valve.