Background: Due to its easy applicability, pulse wave has been proposed as a surrogate of electrocardiogram (ECG) for the analysis of heart rate variability (HRV). However, its smoother waveform precludes accurate measurement of pulse-to-pulse interval by fiducial-point algorithms. Here we report a pulse frequency demodulation (PFDM) technique as a method for extracting instantaneous pulse rate function directly from pulse wave signal and its usefulness for assessing pulse rate variability (PRV). Methods: Simulated pulse wave signals with known pulse interval functions and actual pulse wave signals obtained from 30 subjects with a trans-dermal pulse wave device were analyzed by PFDM. The results were compared with heart rate and HRV assessed from simultaneously recorded ECG. Results: Analysis of simulated data revealed that the PFDM faithfully demodulates source interval function with preserving the frequency characteristics of the function, even when the intervals fluctuate rapidly over a wide range and when the signals include fluctuations in pulse height and baseline. Analysis of actual data revealed that individual means of low and high frequency components of PRV showed good agreement with those of HRV (intraclass correlation coefficient, 0.997 and 0.981, respectively). Conclusion: The PFDM of pulse wave signal provides a reliable assessment of PRV. Given the popularity of pulse wave equipments, PFDM may open new ways to the studies of long-term assessment of cardiovascular variability and dynamics.

Background: Prognoses and long‐term cardiac function of patients with fulminant myocarditis have not been fully elucidated. Therefore, we clarified the prognoses and long‐term cardiac function according to required percutaneous mechanical circulatory support and histological findings among patients with fulminant myocarditis. Methods and Results: We conducted a multicenter retrospective medical record review of 216 patients with fulminant myocarditis requiring percutaneous mechanical circulatory support. Sixty‐one patients were treated with intra‐aortic balloon pump or Impella alone, and 155 patients received veno‐arterial extracorporeal membrane oxygenation and were treated with or without intra‐aortic balloon pump or Impella. Histologically, 107 patients had lymphocytic myocarditis; 34, eosinophilic myocarditis; and 4, giant cell myocarditis. Freedom from composite end point (death, durable left ventricular assist device implantation, and heart transplantation) was 66% at 90 days, 62% at 1 year, and 57% at 6 years. Veno‐arterial extracorporeal membrane oxygenation use was associated with poor prognosis in the multivariable analysis (hazard ratio [HR], 5.27; 95% CI, 1.60–17.36). The eosinophilic myocarditis subgroup showed better prognosis (HR, 0.28; 95% CI, 0.10–0.80) compared with the lymphocytic myocarditis subgroup but not in the multivariable analysis. Ventricular tachycardia/ventricular fibrillation rhythm at admission, high C‐reactive protein level, and no endomyocardial biopsy were also associated with poor prognosis. The left ventricular ejection fraction at 1 year was ≤50% in 16% of patients and was lower in patients with eosinophilic myocarditis (median: 57.9% [48.8–65.0%]) than in those with lymphocytic myocarditis (65.0% [58.6–68.7%]) ( P =0.036). Conclusions: Patients with fulminant myocarditis who received veno‐arterial extracorporeal membrane oxygenation had a poor prognosis. Long‐term cardiac function was impaired in some patients, especially those with eosinophilic myocarditis.

Background: Heart failure with preserved ejection fraction (HFpEF) is frequently observed in older women. Increased arterial stiffness in this population may be a cause of HFpEF. Methods and Results: In 75 patients who underwent cardiac catheterization and who had no significant coronary artery stenosis or left ventricular (LV) wall motion abnormalities, the LV relaxation time constant (Tp) was calculated. The LVEF was obtained from left ventriculography, and plasma brain natriuretic peptide (BNP) level was measured. From the pressure waveforms at the ascending aorta, the augmentation index (AIx) was calculated. Effective arterial elastance (Ea) and total vascular resistance (TVR) were also determined. No significant differences were found between genders for age, heart rate, central blood pressure, or LVEF. Ea, TVR, AIx, and BNP level were significantly greater in women than in men, but only AIx was significantly correlated with Tp (r=0.25, P=0.04) and BNP level (r=0.33, P=0.005). Conclusions: The arterial system is stiffer in women than in men of the same age. Among the parameters of arterial stiffness, only AIx is related to abnormal LV relaxation and increased BNP level. Elevated AIx is a factor that causes LV diastolic dysfunction and may be associated with the development of HFpEF in this gender. (Circ J 2013; 77: 123–129)