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Aims: The first aim of this study was to determine the size of the Koch's triangle. The second one was to investigate relation between its dimensions and other individual-specific and heart-specific parameters as well as to create universal formula to estimate triangle dimensions based on these parameters.Methods and results: This study is a prospective one, presenting 120 randomly selected autopsied hearts dissected from adult humans (Caucasian) of both sexes (31.7% females), with mean age of 49.3 ± 17.4 years. The length of triangle sides and angles were measured and the triangle area was calculated as well. Sixteen additional heart parameters were measured in order to analyse potential relationship between the dimensions of Koch's triangle and other dimensions of the heart, using linear regression analysis. The mean (±SD) length of the anterior edge was approximated to 18.0 ± 3.8 mm, the posterior edge to 20.3 ± 4.3 mm, and the basal edge to 18.5 ± 4.0 mm. The average values of the apex angle, the Eustachian angle, and the septal leaflet angle were 58.0 ± 14.4°, 53.8 ± 10.6°, and 67.6 ± 14.4°, respectively. The mean value of the Koch's triangle area was 151.5 ± 55.8 mm2. The 95th percentile of triangle's height (the distance from the apex to the coronary sinus) was 21.8 mm.Conclusion: Mean values and proportions of triangle's sides and angles were presented. Koch's triangle showed considerable individual variations in size. The dimensions of the triangle were strongly independent from individual-specific and heart-specific morphometric parameters; however, the maximum triangle's height can be estimated as 22 mm. [ABSTRACT FROM AUTHOR]

Variable Strategies for CTI Ablation Objectives This study aimed to investigate the anatomical characteristics complicating cavotricuspid isthmus (CTI) ablation and the effectiveness of various procedural strategies. Methods and Results This study included 446 consecutive patients (362 males; mean age 60.5 ± 10.4 years) in whom CTI ablation was performed. A total of 80 consecutive patients were evaluated in a preliminary study. The anatomy of the CTI was evaluated by multidetector row-computed tomography (MDCT) prior to the procedure. A multivariate logistic regression analysis revealed that the angle and mean wall thickness of the CTI, a concave CTI morphology, and a prominent Eustachian ridge, were associated with a difficult CTI ablation (P < 0.01). In the main study, 366 consecutive patients were divided into 2 groups: a modulation group (catheter inversion technique for a concave aspect, prominent Eustachian ridge, and steep angle of the CTI or increased output for a thicker CTI) and nonmodulation group (conventional strategy). The duration and total amount of radiofrequency energy delivered were significantly shorter and smaller in the modulation group than those in the nonmodulation group (162.2 ± 153.5 vs 222.7 ± 191.9 seconds, P < 0.01, and 16,962.4 ± 11,545.6 vs 24,908.5 ± 22,804.2 J, P < 0.01, respectively). The recurrence rate of type 1 atrial flutter after the CTI ablation in the nonmodulation group was significantly higher than that in the modulation group (6.3 vs 1.7%, P = 0.02). Conclusion Changing the procedural strategies by adaptating them to the anatomical characteristics improved the outcomes of the CTI ablation. [ABSTRACT FROM AUTHOR]

Abstract: The crista terminalis and Eustachian ridge are normal anatomical structures within the right atrium that are not normally looked for or visualised in the standard views obtained while performing a transthoracic echocardiogram (TTE). In this case report, the prominent terminal ridge (a normal anatomical variant) appeared as a “mass” in the right atrium that needed to be differentiated from a pathological cardiac mass. Identification of physiological structures in the right atrium on TTE using additional 3D imaging can avoid unnecessary additional tests that are both more invasive and expensive such as transesophageal echocardiography or MRIs. [Copyright &y& Elsevier]

Background: Although the reentrant circuit of typical atrial flutter (AFL) has been well recognized, the activation around the Eustachian ridge (ER) has not been fully characterized. The aim of this study was to delineate the activation patterns around the ER during typical AFL using high-resolution noncontact mapping. Methods: Fifty-three patients (M/F = 43/10, 62 ± 14 years) with typical AFL were included. The high-resolution mapping of the right atrium using a noncontact mapping system during AFL and pacing from the coronary sinus (CS) was performed to evaluate the conduction through the ER. Results: Three types of activation patterns around the ER could be classified according to the ER conduction during AFL and CS pacing. Type I (n = 21, M/F = 16/5, 61 ± 13 years) exhibited conduction block at the ER during AFL and CS pacing. The local unipolar electrograms at the ER exhibited long double potentials (DPs) (109 ± 12 ms, range 77–153 ms) during AFL and CS pacing (84 ± 18 ms, range 48–129 ms). Type II (n = 8, M/F = 7/1, 61 ± 15 years) exhibited conduction block at the ER during AFL, but conduction through the ER during CS pacing. The unipolar electrograms exhibited long DPs (119 ± 12 ms, range 97–141 ms) at the ER during the tachycardia and an rS pattern during CS pacing. Type III (n = 24, M/F = 20/4, 61 ± 16 years) exhibited an activation wavefront that passed along the ER, with the sinus venosa as the posterior barrier during AFL. During CS pacing, all cases exhibited conduction through the ER with an rS pattern. Conclusions: This study is the first to demonstrate the three patterns of activation along the ER during AFL and CS pacing. This finding suggested that the ER is an anatomic and functional barrier during typical AFL. [ABSTRACT FROM AUTHOR]

This paper reviews the anatomical substrates responsible for the induction and maintenance of supraventricular tachycardia and discusses the ECG findings associated with these tachycardias. The normal anatomy of the supraventricular conducting system, particularly within the atria, is complex with conduction proceeding along preferential pathways, which are in turn determined in part by the anisotropic properties of the atrial myocardium. There appear to be at least dual inputs to the atrioventricular node, a posteriorly situated slow pathway and an anterior fast pathway.It is sometimes possible to relate ECG findings directly to anatomical substrates; for example, in some cases of atrial tachycardia the site of the atrial focus (left or right, superior or inferior) can be determined by the polarity of the P wave. The anatomical substrates responsible for intra-atrial re-entry, atrial flutter and atrial fibrillation relate to anatomical barriers to impulse propagation and areas of slow conduction. In atrial flutter the crista terminalis, Eustachian valve, inferior vena cava, coronary sinus os, and tricuspid annulus have been identified as anatomical barriers to conduction around which a macro re-entrant circuit within the right atrium may conduct, usually in a counter-clockwise direction. Clockwise direction of conduction, and other mechanisms of tachycardia, occur in some of the less typical forms of atrial fluter. Atrial fibrillation is caused by multiple wavelets which randomly conduct through the atrial myocardium and are responsible for the irregular ‘fibrillation waves’ on the ECG.Supraventricular tachycardia presents as a narrow complex tachycardia unless pre-existing or rate-related bundle branch block is present. Less common causes for a broad complex tachycardia occurring in supraventricular tachycardia include an accessory atrioventricular or atriofascicular pathway conducting antegradely during tachycardia, or accessory pathway participation as a bystander during supraventricular tachycardia.ECG features which can help to distinguish between atrioventricular nodal re-entrant tachycardia and atrioventricular re-entrant tachycardia include: (1) the presence of a δ wave during sinus rhythm which is highly suggestive of atrioventricular re-entrant tachycardia as the mechanism of supraventricular tachycardia; (2) the finding of a pseudo s (lead II) or pseudo r′ (lead V1) during tachycardia in atrioventricular nodal re-entrant tachycardia; (3) lengthening of the tachycardia cycle length in cases of atrioventricular re-entrant tachycardia when bundle branch block occurs ipsilateral to the accessory pathway and (4) the finding of QRS alternans during tachycardia which is suggestive of atrioventricular re-entrant tachycardia.‘Long RP’ tachycardia may be caused by an atrial tachycardia due to an inferiorly situated area of abnormal automaticity, atypical atrioventricular nodal re-entrant tachycardia with slow retrograde conduction, or atrioventricular re-entrant tachycardia with an accessory pathway conducting slowly from ventricle to atrium during tachycardia. [ABSTRACT FROM PUBLISHER]

We report a 78-year-old man as the first documented case of double P waves separated by 400 msec on 12-lead ECG. These P waves had different polarities on lead V1. The first P wave represented activation of the lateral wall of the right atrium, and the latter P wave represented activation of the medial right atrium and the left atrium. Widely spaced double potentials were recorded craniocaudally along the line, presumably corresponding to the crista terminalis during sinus rhythm. For this to occur, conduction disturbance has to be present both in the upper and lower right atrium. Conduction disturbance in the upper right atrium would interrupt excitation from the sinus node to the medial wall, and conduction disturbance in the lower right atrium would interrupt excitation spreading from the lower lateral right atrium to the isthmus area where fragmented potentials were recorded. These multiple discrete lesions appear to constitute a unique electrical atriopathy in this patient. [ABSTRACT FROM AUTHOR]

Aims: The first aim of this study was to determine the size of the Koch's triangle. The second one was to investigate relation between its dimensions and other individual-specific and heart-specific parameters as well as to create universal formula to estimate triangle dimensions based on these parameters., Methods and Results: This study is a prospective one, presenting 120 randomly selected autopsied hearts dissected from adult humans (Caucasian) of both sexes (31.7% females), with mean age of 49.3 ± 17.4 years. The length of triangle sides and angles were measured and the triangle area was calculated as well. Sixteen additional heart parameters were measured in order to analyse potential relationship between the dimensions of Koch's triangle and other dimensions of the heart, using linear regression analysis. The mean (±SD) length of the anterior edge was approximated to 18.0 ± 3.8 mm, the posterior edge to 20.3 ± 4.3 mm, and the basal edge to 18.5 ± 4.0 mm. The average values of the apex angle, the Eustachian angle, and the septal leaflet angle were 58.0 ± 14.4°, 53.8 ± 10.6°, and 67.6 ± 14.4°, respectively. The mean value of the Koch's triangle area was 151.5 ± 55.8 mm2. The 95th percentile of triangle's height (the distance from the apex to the coronary sinus) was 21.8 mm., Conclusion: Mean values and proportions of triangle's sides and angles were presented. Koch's triangle showed considerable individual variations in size. The dimensions of the triangle were strongly independent from individual-specific and heart-specific morphometric parameters; however, the maximum triangle's height can be estimated as 22 mm., (Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2016. For permissions please email: journals.permissions@oup.com.)