Exercise tolerance in chronic hypoxemia due to right-to-left shunt.

“…12,14,15,17,18 Shunting of deoxygenated venous blood rich in hydrogen ions and carbon dioxide to the systemic circulation may be a strong stimulus for ventilation. 13 Alveolar hyperventilation, reflected by a decrease in alveolar carbon dioxide and an increase in alveolar oxygen tensions, tends to compensate for the carbon dioxide that bypasses the lungs. 14 Moreover, right-to-left shunting causes pulmonary hypoperfusion and thus an increase in physiological dead-space ventilation that could be an additional stimulant for ventilation.…”

Section: Cyanosis and Ventilatory Patternmentioning

confidence: 99%

“…9 -11 Abnormal exercise ventilatory patterns have been reported in ACHD patients with cyanosis because of right-to-left shunting. [12][13][14][15] If cyanosis has a direct adverse effect on ventilation patterns, it may affect any prognostic value derived from the ventilatory response to exercise.…”

mentioning

confidence: 99%

Abnormal Ventilatory Response to Exercise in Adults With Congenital Heart Disease Relates to Cyanosis and Predicts Survival

et al. 2006

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Background— Limited data exist with which to stratify risk in adult congenital heart disease (ACHD). An increased ventilatory response to exercise, expressed as ventilation per unit of carbon dioxide production (V̇ e /V̇ co 2 slope), is an established predictor of impaired survival in acquired heart disease. We sought to establish the distribution, relation to cyanosis, and prognostic value of the V̇ e /V̇ co 2 slope across a wide spectrum of ACHD patients. Methods and Results— Five hundred sixty ACHD patients of varying diagnoses and 50 healthy controls underwent cardiopulmonary exercise testing at a single laboratory between 2001 and 2004. Patient age was 33.2±12.9 years (mean±SD). Peak oxygen consumption was 23.5±9.0 mL · kg −1 · min −1 . V̇ e /V̇ co 2 slope for all patients was 36.3±15.3. The slope was raised in all ACHD groups compared with controls and was 73% higher in cyanotic patients. Cyanosis, with or without pulmonary arterial hypertension, was the strongest predictor of abnormal V̇ e /V̇ co 2 slope. The V̇ e /V̇ co 2 slope was the most powerful univariate predictor of mortality in the noncyanotic group and the only independent predictor of mortality among exercise parameters on multivariate analysis. In cyanotic patients, no parameter was predictive of death. Conclusions— Ventilatory response to exercise is abnormal across the spectrum of ACHD. Cyanosis is a powerful stimulus for such exaggerated ventilatory patterns irrespective of the presence of pulmonary arterial hypertension. Increased V̇ e /V̇ co 2 slope is the strongest exercise predictor of death in noncyanotic ACHD patients.

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“…The failure of VD/VT to fall with exer cise in our patients despite normal pul monary hemodynamics suggests limita tion of CO; exchange in some regions dur ing exercise due to worsening of regional diffusion/perfusion relationship and/or increased right-to-left shunting [21] result ing from the decreases in transit time through abnormally dilated pulmonary vessels. VD/VT could also rise or fail to fall during exercise if tidal volume did not increase appropriately, in conjunction with a minimal increase in anatomic dead space [22].…”

Section: Discussionmentioning

confidence: 58%

Abnormal Responses of Wasted Ventilation Fraction (VD/VT) during Exercise in Patients with Pulmonary Vascular Abnormalities

Mohsenifar¹,

Tashkin²,

Wolfe³

et al. 1983

Respiration

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The finding of a rise in VD/VT or failure of VD/VT to fall during exercise has been proposed as a useful noninvasive indicator of pulmonary vaso-occlusive disease in patients with unexplained dyspnea. However, we previously reported a normal fall in VD/VT during exercise in patients with pulmonary hypertension at rest and/or during exercise due to collagen vascular disease. To investigate further the relationship between pulmonary vascular abnormalities and VD/VT responses to exercise, we studied 4 subjects with severe hypoxemia due to cirrhosis or diffuse telangiectasia. We found an abnormal VD/VT response to exercise in these subjects despite normal pulmonary hemodynamics which effectively excluded hemodynamically significant pulmonary vascular obstruction. These findings provide further support for the lack of utility of the VD/VT measurement at rest and during exercise as a screening method for detecting pulmonary vaso-occlusive disease, since the VD/VT cannot only fall appropriately during exercise in patients with pulmonary hypertension but can also remain unchanged or rise during exercise in patients with normal pulmonary hemodynamics

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Exercise tolerance in chronic hypoxemia due to right-to-left shunt.

Cited by 37 publications

References 0 publications

Guidelines for Rehabilitation in Patients With Cardiovascular Disease (JCS 2012)

Guidelines for Rehabilitation in Patients With Cardiovascular Disease (JCS 2012)

Abnormal Ventilatory Response to Exercise in Adults With Congenital Heart Disease Relates to Cyanosis and Predicts Survival

Abnormal Responses of Wasted Ventilation Fraction (VD/VT) during Exercise in Patients with Pulmonary Vascular Abnormalities

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