Method for measurement of systolic and diastolic time intervals

Abstract

A method and apparatus for determining cardiac time intervals that can measure physiological data noninvasively. Arterial pulse values are measured either invasively or noninvasively, from which left ventricular waveform data is generated. Systolic and diastolic time intervals are derived based on the left ventricular waveform data.

1 . A method of obtaining information about cardiac events of a patient, comprising: 
 acquiring waveform data that is a function of arterial blood pressure;    extrapolating a first waveform segment from a neighboring portion of the waveform data; and    establishing a first location for a first left ventricle cardiac event on the first waveform segment.    
   
   
       2 . The method of  claim 1  further comprising: 
 extrapolating a second waveform segment from a neighboring portion of the waveform data; and    establishing a second location for a second left ventricle cardiac event on the second waveform segment.    
   
   
       3 . The method of  claim 1  further comprising: 
 establishing a third location for a third cardiac event on either the first waveform segment or the waveform data; and    calculating a cardiac time interval from the first location and the third location.    
   
   
       4 . The method of  claim 2  further comprising: 
 establishing a third location for a third cardiac event on either the first pressure waveform segment or the waveform data;    calculating a first cardiac time interval from the first location and the third location;    establishing a fourth location for a fourth cardiac event on either the second pressure waveform segment or the waveform data; and    calculating a second cardiac time interval from the second location and the fourth location.    
   
   
       5 . The method of  claim 4  further comprising calculating a third cardiac time interval from the third location and the fourth location.  
   
   
       6 . The method of  claim 5  further comprising: 
 acquiring additional waveform data that is a function of arterial blood pressure;    extrapolating a third waveform segment from a neighboring portion of the additional waveform data;    establishing a fifth location for a fifth left ventricle cardiac event on the third waveform segment; and    calculating a fourth cardiac time interval from the second location and the fifth location.    
   
   
       7 . The method of  claim 6  wherein: 
 the first location approximates mitral valve closure for a first heartbeat;    the second location approximates mitral valve opening for the first heartbeat;    the third location approximates aortic valve opening for the first heartbeat;    the fourth location approximates aortic valve closure for the first heartbeat;    the fifth location approximates mitral valve closure for a second heartbeat immediately following the first heartbeat;    the first cardiac time interval is isovolumetric contraction time;    the second cardiac time interval is isovolumetric relaxation time;    the third cardiac time interval is left ventricular ejection time; and    the fourth cardiac time interval is rapid filling time.    
   
   
       8 . The method of  claim 1  wherein the waveform data acquiring step comprises measuring the waveform data noninvasively.  
   
   
       9 . The method of  claim 1  wherein the waveform data acquiring step comprises measuring the waveform data invasively.  
   
   
       10 . The method of  claim 1  wherein the waveform data acquiring step comprises acquiring waveform data that is a function of arterial radial blood pressure.  
   
   
       11 . The method of  claim 3  wherein the cardiac time interval is isovolumetric contraction time or isovolumetric relaxation time.  
   
   
       12 . The method of  claim 1  wherein: 
 the acquired waveform data is pressure waveform data;    the first waveform segment is a pressure waveform; and    the first location establishing step comprises: 
 establishing a pressure value approximating left ventricular pressure at mitral valve closure; and  
 identifying the first location as a point on the first waveform segment corresponding to the pressure value.  
   
   
   
       13 . The method of  claim 1  wherein: 
 the acquired waveform data is pressure waveform data;    the first waveform segment is a pressure waveform; and    the first location establishing step comprises: 
 establishing a pressure value approximating left ventricular pressure at mitral valve opening; and  
 identifying the first location as a point on the first waveform segment corresponding to the first pressure value.  
   
   
   
       14 . The method of  claim 2  wherein: 
 the acquired waveform data is pressure waveform data;    the first waveform segment is a pressure waveform;    the first location establishing step comprises: 
 establishing a first pressure value approximating left ventricular pressure at mitral valve closure; and  
 identifying the first location as a point on the first waveform segment corresponding to the first pressure value; and  
   the second location establishing step comprises: 
 establishing a second pressure value approximating left ventricular pressure at mitral valve opening, the second pressure value being greater than the first pressure value; and  
 identifying the second location as a point on the second waveform segment corresponding to the second pressure value.  
   
   
   
       15 . The method of  claim 1  wherein the extrapolating step comprises extrapolating the first waveform segment from the waveform data using a first order linear function, a second order linear function, or an exponential function.