title: Exercise-induced upward shift of diastolic left ventricular pressure-volume relation in patients with dilated cardiomyopathy. Effects of beta-adrenoceptor blockade.
abstract: BACKGROUND
  The effectiveness of beta-blocker therapy for dilated cardiomyopathy (DCM) may be attributed to the inhibition of detrimental effects on the failing heart of sympathetic stimulation during exertion. However, the harmful effects of activity as well as the protective effects of beta-blockers have not been demonstrated. Diastolic ventricular function is known to be sensitive to transient myocardial metabolic insult. In this study, we investigated the effect of modest exercise with or without beta-blockade on the diastolic left ventricular pressure-volume (P-V) relation in patients with DCM.
  
  
  RESULTS
  The diastolic left ventricular P-V relation was obtained by high-fidelity pressure measurements and digital subtraction left ventriculography at rest and immediately after modest supine bicycle exercise in 12 patients with DCM. The effects of intravenous administration of 0.1 mg/kg propranolol on resting and exercise P-V relations were studied. The end-diastolic and lowest left ventricular pressures were significantly elevated by exercise (20 +/- 9 to 32 +/- 13 mm Hg, P < .01, and 12 +/- 6 to 21 +/- 11 mm Hg, P < .01, respectively) despite insignificant changes in left ventricular volumes. The administration of propranolol did not alter the resting diastolic P-V relation. However, propranolol significantly attenuated the exercise-induced upward shift of the diastolic P-V relation despite a significant increase in end-diastolic volume. The significant upward shift and attenuation by propranolol were also observed even when the left ventricular pressure was corrected by the subtraction of right atrial pressure.
  
  
  CONCLUSIONS
  These results indicate that even modest exercise exerts detrimental effects on diastolic left ventricular function of the failing heart through beta-adrenergic stimulation. The clinical effectiveness of beta-blocker therapy in patients with DCM can be attributed in part to the inhibition of detrimental myocardial effects of sympathetic stimulation during daily activity.
authors.affiliation: First Department of Medicine, Osaka University School of Medicine, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Sato
authors.forename: M
authors.initials: M
authors.lastname: Hori
authors.forename: H
authors.initials: H
authors.lastname: Ozaki
authors.forename: H
authors.initials: H
authors.lastname: Yokoyama
authors.forename: K
authors.initials: K
authors.lastname: Imai
authors.forename: M
authors.initials: M
authors.lastname: Morikawa
authors.forename: H
authors.initials: H
authors.lastname: Takeda
authors.forename: M
authors.initials: M
authors.lastname: Inoue
authors.forename: T
authors.initials: T
authors.lastname: Kamada
mesh_terms: D000319:Adrenergic beta-Antagonists / Q000627:therapeutic use*; D000328:Adult; D001022:Aortic Valve Insufficiency / Q000150:complications / Q000503:physiopathology; D001794:Blood Pressure; D001810:Blood Volume; D002303:Cardiac Output, Low / Q000209:etiology / Q000503:physiopathology; D002311:Cardiomyopathy, Dilated / Q000150:complications / Q000188:drug therapy / Q000503:physiopathology*; D003971:Diastole; D015444:Exercise; D006439:Hemodynamics / Q000187:drug effects; D006801:Humans; D008297:Male; D008875:Middle Aged; D011433:Propranolol / Q000627:therapeutic use; D012146:Rest; D016277:Ventricular Function, Left
chemical_list: D000319:Adrenergic beta-Antagonists; D011433:Propranolol