The combined effects of orthostatic and mental stress on heart rate, T-wave amplitude, and pulse transit time

1993 ◽  
Vol 67 (6) ◽  
pp. 540-544 ◽  
Author(s):  
Attila Szabo
Keyword(s):  
Heart Rate ◽  
Transit Time ◽  
Mental Stress ◽  
Wave Amplitude ◽  
Pulse Transit Time ◽  
Combined Effects ◽  
T Wave

Heart activity during experimental diving of snakes

1959 ◽  
Vol 197 (3) ◽  
pp. 604-606 ◽  
Author(s):  
Kjell Johansen
Keyword(s):  
Heart Rate ◽  
Wave Amplitude ◽  
Heart Activity ◽  
Depressant Effect ◽  
T Wave ◽  
Electrocardiographic Findings

Diving bradycardia has been demonstrated in snakes, ( Tropidonotus natrix). The bradycardia was developed rapidly and amounted to a reduction in heart rate of about 85%. The electrocardiographic findings revealed the slowing of the heart rate as effected mainly through a prolongation of the diastole, amounting to 30 times the prediving value. Duration of the electrical systole showed a prolongation of the P-R interval by 15% and the Q-T interval by 130%. A rapid and pronounced shift in the T-wave amplitude occurred upon submersion. The results suggest that the described T-wave shifts are due to changes in concentration of CO2 in the organism. Increased concentrations of CO2 in the respiratory air induced bradycardia and had a depressant effect on respiration.

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