This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Kussmaul, W. G. Articles by Laskey, W. K. Search for Related Content PubMed PubMed Citation Articles by Kussmaul, W. G., 3d Articles by Laskey, W. K.

Circulation, Vol 88, 1010-1015, Copyright © 1993 by American Heart Association

ARTICLES

Right ventricular-vascular interaction in congestive heart failure. Importance of low-frequency impedance

WG Kussmaul 3d, JA Altschuler, WH Matthai and WK Laskey
Department of Medicine, University of Pennsylvania School of Medicine, Philadelphia.

BACKGROUND. Vasodilator agents are widely used in congestive heart failure. These agents may have important effects on the pulsatile aspects of right ventricular hydraulic load. METHODS AND RESULTS. Fifteen patients with severe congestive heart failure were studied during cardiac catheterization by use of high-fidelity pressure transducers and a catheter-mounted flow velocity probe. Three graded doses of nitroprusside were infused as pulmonary artery (PA) pressure and flow were continuously recorded. From Fourier transforms of signal- averaged waves, PA impedance, hydraulic power, and wave reflection indices were derived. At the highest dose of nitroprusside (66 +/- 41 micrograms/min), cardiac output was significantly improved, whereas PA mean and wedge pressure, resistance, impedance at the first harmonic, characteristic impedance, and wave reflection amplitude were all reduced. At the dose (32 +/- 20 micrograms/min) at which cardiac output first showed improvement, only PA mean pressure and first-harmonic impedance were significantly reduced. Hydraulic power cost per unit of forward flow was also lowered at this dose, despite lack of significant change in pulmonary vascular resistance. At the lowest dose of nitroprusside (11 +/- 4 micrograms/min), six patients experienced a decrease in stroke volume, whereas the other nine were either unchanged (n = 1) or showed an increase (n = 8). Multiple regression revealed that only the change in first-harmonic impedance correlated with this effect, increasing when stroke volume decreased and decreasing when stroke volume increased (P = .02). The change in first-harmonic impedance at this dose appeared to be caused by alterations in the amplitude of PA wave reflections. At higher doses, changes in mean PA pressure (but not in pulmonary vascular resistance) correlated with changes in stroke volume. CONCLUSIONS. Nitroprusside vasodilation at low doses alters PA hemodynamics in congestive heart failure primarily through changes in low-frequency impedance. In some patients, this effect is associated with decreased stroke output. At higher doses, favorable alterations in resistance, low- and high-frequency impedance, and wave reflections all contribute to increased forward flow and decreased power requirement per unit forward flow. These findings show that ventricular-vascular interaction is importantly affected by pulmonary vasodilation and that appreciation of pulsatile properties is required to understand the effects of pulmonary vasodilation on cardiac output.

This article has been cited by other articles:

				H Senzaki, Y Iwamoto, H Ishido, T Matsunaga, M Taketazu, T Kobayashi, H Asano, T Katogi, and S Kyo Arterial haemodynamics in patients after repair of tetralogy of Fallot: influence on left ventricular after load and aortic dilatation Heart, January 1, 2008; 94(1): 70 - 74. [Abstract] [Full Text] [PDF]

				S. Huez, S. Brimioulle, R. Naeije, and J.-L. Vachiery Feasibility of Routine Pulmonary Arterial Impedance Measurements in Pulmonary Hypertension Chest, June 1, 2004; 125(6): 2121 - 2128. [Abstract] [Full Text] [PDF]

				H. Senzaki, S. Masutani, J. Kobayashi, T. Kobayashi, N. Sasaki, H. Asano, S. Kyo, Y. Yokote, and A. Ishizawa Ventricular Afterload and Ventricular Work in Fontan Circulation: Comparison With Normal Two-Ventricle Circulation and Single-Ventricle Circulation With Blalock-Taussig Shunts Circulation, June 18, 2002; 105(24): 2885 - 2892. [Abstract] [Full Text] [PDF]

				J. W. Haft, P. Montoya, O. Alnajjar, S. R. Posner, J. L. Bull, M. D. Iannettoni, R. H. Bartlett, and R. B. Hirschl An artificial lung reduces pulmonary impedance and improves right ventricular efficiency in pulmonary hypertension J. Thorac. Cardiovasc. Surg., December 1, 2001; 122(6): 1094 - 1100. [Abstract] [Full Text] [PDF]

				V. Castelain, P. Herve, Y. Lecarpentier, P. Duroux, G. Simonneau, and D. Chemla Pulmonary artery pulse pressure and wave reflection in chronic pulmonary thromboembolism and primary pulmonary hypertension J. Am. Coll. Cardiol., March 15, 2001; 37(4): 1085 - 1092. [Abstract] [Full Text] [PDF]

				P. Castiglioni, R. Tommasini, M. Morpurgo, and M. Di Rienzo Modulation of pulmonary arterial input impedance during transition from inspiration to expiration J Appl Physiol, December 1, 1997; 83(6): 2123 - 2130. [Abstract] [Full Text] [PDF]