Influence of acute hypertension on aortic valve competence

The effect of acutely induced hypertension on aortic valve competence was studied in anesthetized dogs. Aortic pressure was increased by infusion of methoxamine or mechanically; aortic valve competence was evaluated by aortogrphy and by indicator dye. The aortic valve was normally competent; aortic insufficiency appeared with increase of mean pressure by as little as 20-50 mmHg; 6 of 9 animals showed aortic incompetence when mean aortic pressure was elevated 45-70 mmHg, but the valve remained competent in 2 of 9 animals with mean pressure increments of 60-90 mmHg. The aortic root was appreciably less distensible than was the proximal descending aorta; this factor may limit the degree of aortic insufficiency in response to acute hypertension in the dog.