title: Factors that affect pulse wave time transmission in the monitoring of cardiovascular system.
abstract: OBJECTIVE
  Vascular transit time (VTT) can be defined as the first heart sound of the phonocardiography (PCG) signal to its arrival at the photoplethysmography (PPG). Studies have shown that monitoring VTT can be useful as an early prognosis of cardiac diseases. However, there is limited study conducted to understand the physiologic factors that affect VTT at the upper limb. In this study, the effect associated with difference in subject height, weight, heart rate, mean arterial pressure, systolic and diastolic blood pressure was assessed.
  
  
  METHODS
  A study population of 31 healthy Chinese young adults (21 male; age range 20-33 yr) were recruited. PCG and PPG were recorded non-invasively from the fourth costal cartilage at the midclavicular line and right index finger, respectively. A single sample Kolmogorov-Smirnov (K-S) goodness-of-fit hypothesis test, a univariate linear regression analysis, and a multiple linear regression modelling were performed on the VTT measurements and the associated physiologic parameters.
  
  
  RESULTS
  The results from the K-S test showed that the physiologic parameters and VTT measurements had a normal cumulative distribution function. Furthermore, all physiologic parameters were significantly and independently related to VTT (P < 0.05). Based on these physiological parameters, a VTT regression model was also derived (r (2) = 0.79).
  
  
  CONCLUSIONS
  The findings herein suggest that the observed physiologic parameters have significant contributions to the nominal VTT value of a subject. Unlike pulse transit time, the VTT technique has the added advantage that the left ventricular isometric contraction time is not included in the timing derivation.
authors: Division of Research, Singapore General Hospital, 31 Third Hospital Avenue, Bowyer Block A Level 3, Outram Road, Singapore 169608, Singapore, foo.jong.yong@sgh.com.sg
authors: Jong Yong A
authors: JY
authors: Foo
authors: Stephen J
authors: SJ
authors: Wilson
authors: Ping
authors: P
authors: Wang
mesh_terms: D000328:Adult; D001776:Blood Circulation Time / Q000379:methods*; D001795:Blood Pressure Determination; D005260:Female; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D016014:Linear Models; D008297:Male; D009200:Myocardial Contraction / Q000502:physiology; D010701:Phonocardiography; D017156:Photoplethysmography; D011674:Pulse; D034941:Upper Extremity / Q000502:physiology