**8. PVF and AF progression**

90 Echocardiography – In Specific Diseases

Pharmacological AF management is mainly divided into rhythm control and rate control strategies, both of which show equivalent outcomes in long-term prognosis of AF patients provided that appropriate anticoagulation therapy is conducted (Wyse, 2005). However, choice of better strategy based only on electrophysiologic or electrocardiographic perspectives seems insufficient. PVF evaluation has the potential to play a role in this decision-making process, i.e., PVF recording enables evaluation of contractile LA and PV functions, which vary during the long period of AF remodeling affecting both LA and PV. For AF management, it is important to assess the stage of AF progression in individual AF patient with different clinical background. For this purpose, assessment of LA stiffness or contractility and severity of PV regurgitation by PVF profile is important for AF

Radiofrequency catheter ablation is widely conducted in many electrophysiologic laboratories. It is a first line therapy for 'focal' AF originating from PV, and is currently applied not only to paroxysmal AF but also to persistent AF. Remodeling makes AF drugrefractory. Moreover, antiarrhythmic drugs often suppress cardiac performance (negative inotropism) and are sometimes arrhythmogenic (proarrhythmic effects). The main

Fig. 9. Receiver-operating curve (ROC) discriminated PV backflow velocity (PVBV) as the best predictor of the progression of AF. Areas under the ROC for PVBV, left atrial fractional shortening (LAFS) and left atrial diameter at end-diastole (LADd) are 0.873, 0.740 and 0.623, respectively. Cut-off PVBV for predicting future AF perpetuation is 21.8 cm/sec (sensitivity 84.6%, specificity 78.3%). LAFS is calculated by equation (1) in the text. (From Maruyama, T.; Kishikawa, T.; Ito, H.; Kaji, Y.; Sasaki, Y. & Ishihara, Y. Augmentation of pulmonary vein backflow velocity during left atrial contraction: a novel phenomenon responsible for

progression of atrial fibrillation in hypertensive patients. *Cardiology* Vol. 109, No. 1, 2008, pp.

**7. PVF in AF management** 

management in individual patient.

33-40, with permission.)

All the components of PVF have the potential role to evaluate AF progression, i.e., **S** wave attenuation and consequent relative **D** wave augmentation indicate impaired LA relaxation and compliance. Considering increased **D** and **Ar** wave amplitudes during sinus rhythm in AF patients, PVF increases exclusively during LV diastole, whichever PVF direction is forward (e.g., **D** wave) or backward (e.g., **Ar** wave). If ectopic beats originating from PV are mechanically triggered, these echocardiographic findings indicate that ectopic beats are prone to occur during diastole. Therefore, repetitive PV ectopic beats easily capture ventricles that are out of refractory period, and induce rapid ventricular response during 'focal' AF. This is important because rapid AF is easy to promote electrical remodeling (Wijffels et al., 1995).

Fig. 10. Possible mechanisms of reversed PV flow (**Ar** wave) augmentation contributing to the AF progression.

Pulmonary Venous Flow Pattern and Atrial Fibrillation: Fact and Controversy 93

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AF progression is reported to be associated with greater PV diameter (Knackstedt et al., 2003; Tsao et al., 2001) as a consequence of PV remodeling (Scharf et al., 2003). Although the relation of AF and PV contraction remains to be fully investigated, augmentation of **Ar** wave (e.g., PVBV) may cause cyclic stretching of highly compliant myocardial sleeves in PV, repetitive ectopic beats and loss of 'sphincter' function, which underlie further PV regurgitation. Therefore, **D** and **Ar** waves augmentation, PV myocardial sleeve stretching and ectopic beats form a vicious cycle leading to PV remodeling. A possible mechanism by which PV characteristics contribute to AF progression is demonstrated in **Fig. 10**.
