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  • Title: The contribution of atrial contraction to right heart function before and after right ventriculotomy. Experimental and clinical observations.
    Author: Guyton RA, Andrews MJ, Hickey PR, Michaelis LL, Morrow AG.
    Journal: J Thorac Cardiovasc Surg; 1976 Jan; 71(1):1-10. PubMed ID: 765626.
    Abstract:
    Effective atrial contraction was abolished by simultaneous atrial and ventricular (A-V) pacing in an acute canine preparation. At constant cardiac output, aortic pressure, and heart rate, only a small rise (1.4 mm. Hg) in mean right atrial pressure was observed before vertical right ventriculotomy, but a larger rise (9.5 mm Hg) occurred after ventriculotomy (p less than 0.01). Right heart failure with tricuspid regurgitation was induced after ventriculotomy by volume overload and A-V pacing. Restoration of atrial contraction (sequential A-V pacing) eliminated regurgitation and lowered average mean right atrial pressure from 22 to 4 mm. Hg (p less than 0.001). After right ventriculotomy, loss of atrial contraction at a constant right atrial pressure resulted in a 42 per cent reduction in cardiac output. In 8 patients who had had right ventriculotomies, abolition of effective atrial contraction by A-V pacing caused an average reduction in cardiac output of 22 per cent, whereas cardiac output fell only 5 per cent in 5 control patients (p less than 0.01).
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