title: Assessment of Cardiac Autonomic Functions in Medical Students With Type D Personality.
abstract: BACKGROUND
  Type D personality experiences joint occurrence of Negative Affectivity and Social Inhibition. It is an emerging risk factor for cardiovascular disease, with prevalence being 18-53% among cardiac patients. Type D personality people have exaggerated cardiovascular activity mediated by increased sympathetic drive and decreased vagal control of the heart which leads to enhanced risk of hypertension and is an independent risk factor for coronary heart disease.
  
  
  OBJECTIVE
  To compare the cardiac autonomic function of Type D and non-Type D students. To compare cardiac autonomic functions among male and female students and students with and without family history of hypertension and coronary artery disease among Type D. To find the most affected test among Type D students.
  
  
  METHODS
  Thirty Type D and 30 non- Type D medical students were identified by DS14. The Parasympathetic cardiac autonomic tests done assessed Heart Rate response to valsalva manoeuvre, immediate heart rate response to standing and heart rate variation during deep breathing. Sympathetic tests assessed BP response to standing and Sustained Hand Grip. The heart rate and R-R interval measurement were got from lead II of ECG recordings on Polyrite D. Statistical analysis was done using SPSS software. Unpaired student's t-test was used and p-value <0.05 was considered to be statistically significant.
  
  
  RESULTS
  Type D students showed slightly decreased parasympathetic activity and increased sympathetic activity when compared to non-Type D students even though there was no statistically significant difference between them. There is a statistically significant decrease in valsalva ratio among females (p<0.01) when compared to males. There is a statistically significant decrease in 30:15 ratio and BP response to handgrip (p<0.05) among students with family history of hypertension and coronary artery disease when compared with students with no family history of coronary artery disease. Valsalva ratio is the most affected test in Type D students.
  
  
  CONCLUSIONS
  Cardiac autonomic functions of Type D personality persons without cardiovascular disease is not different from that of non-Type D. Regular follow up studies over years are required to find if Type D personality is associated with cardiovascular risk in healthy individuals.
authors.affiliation: Associate Professor, Department of Physiology, PSG Institute of Medical Sciences and Research (PSG IMS&R) , Coimbatore, Tamil Nadu, India .
authors.forename: Shuba
authors.initials: S
authors.lastname: Narasimhan
authors.affiliation: CRRI, PSG IMS&R, PSG Institute of Medical Sciences and Research (PSG IMS&R) , Coimbatore, Tamil Nadu, India .
authors.forename: R Abhilasha Singh
authors.initials: RA
authors.lastname: Panwar
keywords: DS14; Negative emotions; Parasympathetic activity; Sympathetic activity; Valsalva ratio