Furthermore the difference in the mean S A interval
Furthermore, the difference in the mean S–A interval between HB capture and non-capture in the 4 patients with conduction pattern 2 or 3 was only 20±4ms (range, 16–27ms), and was shorter than the HV interval after ablation in 3 patients (75%). By contrast, in patients with strictly AV nodal retrograde conduction, whereby ventricular capture without HB capture propagates to the atrium via the ventricular myocardium and right bundle branch, the difference in the S–A interval between capture and non-capture should theoretically be at least equal to (a) the interval between the pacing site and entry of the wavefront into the right bundle branch, plus (b) the interval between the entry into the right bundle branch and the HB, which is nearly the same as the HV interval [1,2]. The value of this difference, however, has not been reported previously. Thus, we hypothesize that a smaller difference in the S–A interval between capture and non-capture of the HB excludes the AV CA-074 Me as the retrograde pathway. Further studies are needed to confirm this hypothesis.
In summary, this study illustrates a plausible pitfall of PHP: in >20% of patients presenting with a posteroseptal AP, we could not determine whether retrograde conduction occurred via the AV node or via the AP because of the absence of a ventricular electrogram on the CS recording, which precluded the measurement of the V–A interval near the septal AP during PHP. In these patients, the AP versus the AV node should not be discriminated solely on the basis of a shortening of the S–A interval when the HB is captured. This pitfall is not a real limitation of PHP. Instead, PHP should be performed using another deflectable catheter or ablation catheter to obtain the local ventricular electrogram near the AP from the intraventricular cavity, making it easier to distinguish VA conduction through the AP from that occurring through the AV node. In addition, by using ventricular premature stimulation during tachycardia, retrograde conduction through the septal AP and AV node can be easily differentiated.
Conflict of interest
Introduction In clinical practice, quantification of serum phosphate levels is useful for the diagnosis and management of various disorders including bone, parathyroid, and renal diseases . In addition, recent studies have shown that high levels of serum phosphate, even within the normal range, may contribute to the increased risk of cardiovascular disease such as myocardial infarction and heart failure [2–4]. Interestingly, Ess et al. have reported that the association of serum phosphate concentrations with disease severity and long-term outcome in patients with chronic heart failure (CHF) is independent from concomitant renal dysfunction . Their data suggest that management focused on serum phosphate levels might be important for patients with CHF. Cardiac resynchronization therapy (CRT) is an effective treatment for drug-refractory severe heart failure with electro-mechanical delay. Previous studies have demonstrated that CRT improves clinical symptoms, exercise capacity, quality of life, and mortality in CHF [5–7]. However, responses to CRT have not been assured in all CHF patients, with about 30% of patients not responding to CRT .
Material and methods
Discussion CRT has been proven to be effective in improving clinical symptoms, exercise capacity, quality of life, and mortality in CHF patients with impaired left ventricular systolic function and intraventricular conduction delay [5–7]. However, such responses to CRT have not been recognized in all CRT candidates, with 30% of patients not responding to CRT . Therefore, various clinical studies have attempted to identify parameters that might predict a response to CRT using either selection criteria [10–13]. These include not only the QRS duration and cardiac dyssynchronous parameters assessed by the echocardiography, but also biomarkers such as BNP, eGFR, and hs-CRP. Our present study demonstrated for the first time that serum phosphate levels might predict responders to CRT, as well as patients who experience adverse cardiac events, in CHF patients treated with CRT-D.