ABSTRACT
BACKGROUND: Exercise training improves endothelium-dependent vasodilation in animals. This study was designed to determine whether forearm exercise training improves endothelium-dependent vasodilation in control subjects and patients with heart failure, a disease associated with abnormal endothelium-dependent vasodilation. METHODS AND RESULTS: We used strain gauge plethysmography to assess the effects of short-term forearm exercise training on resistance vessel function in 11 control subjects and 7 patients with New York Heart Association class II and III heart failure. Subjects performed 30 minutes of handgrip exercise four times a week for 4-6 weeks. In the control subjects, exercise training increased forearm blood flow (FBF) responses to intra-arterial acetylcholine (20 microg/min) from 6.9 +/- 3.1 to 12.2 +/- 3.0 mL/min/100 mL and peak reactive hyperemic FBF responses from 38.1 +/- 5.6 to 47.4 +/- 5.6 (P < .05). Basal FBF and responses to nitroprusside, L-N-monomethyl arginine and acute forearm exercise were not significantly changed. In the patients with heart failure, chronic forearm exercise did not significantly change any of the above-measured parameters. CONCLUSION: Forearm exercise training improves endothelium-dependent vasodilation and peak hyperemic FBF in control subjects but not in patients with heart failure. These data suggest that resistance vessel abnormalities may not be as readily modifiable by exercise training in patients with heart failure compared with control subjects.
Subject(s)
Endothelium, Vascular/metabolism , Exercise/physiology , Forearm/blood supply , Heart Failure/physiopathology , Vascular Resistance/physiology , Acetylcholine/pharmacology , Adult , Aged , Aged, 80 and over , Analysis of Variance , Arginine/blood , Brachial Artery/drug effects , Brachial Artery/physiopathology , Dose-Response Relationship, Drug , Enzyme Inhibitors/pharmacology , Exercise Therapy , Female , Hand Strength/physiology , Heart Failure/rehabilitation , Humans , Infusions, Intra-Arterial , Male , Middle Aged , Muscle Contraction/physiology , Nitric Oxide/metabolism , Nitroprusside/administration & dosage , Nitroprusside/pharmacology , Plethysmography , Regional Blood Flow/drug effects , Vasodilation/drug effects , Vasodilator Agents/pharmacology , omega-N-Methylarginine/pharmacologyABSTRACT
Recent studies have demonstrated that pulmonary artery diastolic (PAD) pressure can be measured from a transducer positioned in the right ventricle (RV) based on the finding that PAD and RV pressures are equal at the time of pulmonary valve opening, which is associated with the time of maximum positive rate of pressure development (dP/dtmax) in the ventricle. The objective of this study was to assess the correlation between estimated PAD (ePAD) pressure, obtained through a RV transducer, and actual PAD (aPAD) pressure in patients with heart failure who have abnormal hemodynamics, reduced systolic function, and variable degrees of mitral regurgitation (MR) and tricuspid regurgitation (TR). Simultaneous measurements of pulmonary artery and RV pressures were obtained with a high-fidelity Millar catheter (Millar Instruments, Houston, TX) in 10 patients with New York Heart Association class III-IV heart failure who were being evaluated for cardiac transplantation. The overall correlation between ePAD and aPAD pressures was .92 (R2 = .878). This was not significantly different during the Valsalva maneuver (r = .96, R2 = .943), submaximal bicycle exercise (r = .87, R2 = .756), or infusions of dobutamine and nitroglycerin (r = .82, R2 = .730). The overall average difference between the average ePAD (24.6 +/- 7.0 mmHg) and aPAD (23.6 +/- 7.0 mmHg) pressures was 1.0 +/- 3.4 mmHg. The average difference between the two pressures in patients with mild to severe MR or TR was not different compared to those patients with no or trace MR or TR. The estimation of PAD pressure from an RV transducer is valid in patients with heart failure who have abnormal hemodynamics, reduced systolic function, and variable degrees of MR and TR. This correlation was observed at rest and during several provocative maneuvers. These data will be important for the development of a chronic, implantable hemodynamic monitor for patients with heart failure.
