Cardiogenic hypertension in maturing dogs.
The purpose of this study was to evaluate whether the heart can induce high blood pressure by maintaining an inappropriately elevated cardiac output/body weight ratio during growth. Direct (femoral artery) mean arterial pressure (MAP), heart rate, cardiac output/body weight ratio (as defined by M-mode echocardiography), and total peripheral vascular resistance were measured and calculated every 2 months in nine conscious dogs during development from 2 to 10 months of age. In four dogs a J-shaped catheter for atrial pacing was chronically implanted at the age of 3 months, and their hearts were permanently paced at 130 beats/min until maturity. The aim of atrial pacing was to prevent the natural slowing of the heart rate and, consequently, to maintain a cardiac output/body weight ratio that was inappropriately high in relation to age during growth. Five dogs were studied as controls. No hemodynamic differences were observed until the age of 4 months. From the age of 5 to 10 months heart rate was kept at 130 beats/min by atrial pacing in the atrially paced group, and the mean cardiac output/body weight ratio did not decrease (196 +/- 24 vs 191 +/- 34 [SE] ml/min/kg). MAP rose from 62 +/- 4 to 116 +/- 8 mm Hg, and total peripheral resistance increased from 0.34 +/- 0.07 to to 0.61 +/- 0.09 mm Hg/ml/min/kg.(ABSTRACT TRUNCATED AT 250 WORDS)
Magrini
F
F
Istituto di Clinica Medica Generale e Terapia Medica, Università di Milano, Italy.
Roberts
N
N
Branzi
G
G
Mondadori
C
C
Reggiani
P
P
Ciulla
M
M
Meazza
R
R
D000375:Aging / Q000502:physiology*; D000818:Animals; D000831:Animals, Newborn / Q000254:growth & development* / Q000502:physiology; D001158:Arteries; D001794:Blood Pressure; D001835:Body Weight; D002302:Cardiac Output; D002304:Cardiac Pacing, Artificial; D004285:Dogs; D006321:Heart / Q000502:physiology*; D006339:Heart Rate; D006973:Hypertension / Q000209:etiology*; D010100:Oxygen / Q000097:blood; D012016:Reference Values; D013997:Time Factors; D014655:Vascular Resistance; D014680:Veins
D010100:Oxygen