Primary Pulmonary Hypertension

Wagenvoort, C. A.; Wagenvoort, Noeke

doi:10.1161/01.cir.42.6.1163

Cited by 491 publications

(37 citation statements)

References 64 publications

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“…7). The slightly higher resting pulmonary vascular resistance observed in the 3-month-old lambs can be attributed to either the presence of relatively more pulmonary vascular smooth muscle (35) and/or more sympathetic adrenergic innervation of the pulmonary vessels. That distention of the main pulmonary artery produced similar changes in the pulmonary vascular resistance in the 3-month-old and adult groups suggests that the responsiveness to distention declines faster with increasing age than the pulmonary vascular muscle decreases.…”

Section: Discussionmentioning

confidence: 85%

Pulmonary Arterial Hypertension Induced by Distention of the Main Pulmonary Artery in Conscious Newborn, Young, and Adult Sheep

et al. 1980

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SummaryDistention of the main pulmonary artery by balloon inflation in sheep results in presumably reflex elevation of pulmonary arterial pressure and resistance distal to the balloon. This response to main pulmonary artery distention is significantly greater in newborn lambs than in older lambs or adult sheep. In several of the newborn lambs, pulmonary artery pressure was raised to suprasystemic levels. Further, in some of the newborn animals, these increases in pulmonary artery pressure and resistance were sustained after deflation of the balloon for periods up to 2 hr. The functional significance of this pulmonary hypertension reflex was not elucidated. However, the data strongly suggest that this reflex may contribute to the maintenance of high pulmonary vascular resistance during fetal and early neonatal life. SpeculationProximal distention of the main pulmonary artery induces a positive feedback reflex which significantly elevates pulmonary artery pressure and resistance. We postulate that this reflex operates in conjunction with hypoxia to maintain high pulmonary vascular resistance in the fetus. It is possible that at birth this reflex mechanism operates in reverse to help lower the pulmonary vascular resistance smoothly, thus avoiding volume overload of the neonatal lungs and left ventricle. Finally, we postulate that this reflex may play a role in the pathogenesis of the persistant fetal circulation syndrome (7).In the conscious adult dog distention of the proximal main pulmonary artery, near the bifurcation, by a partially inflated balloon, results in a significant elevation of pulmonary artery pressure distal (as well as proximal) to the balloon (19,20,22). This elevation in pressure is produced by an increase in pulmonary vascular resistance which occurred without significant change in right ventricular end-diastolic pressure, aortic pressure, and cardiac output. Left atrial pressure either did not change or decreased. We have reported that stepwise balloon distention of the main pulmona artery results in step increases in pulmonary artery pressure abwnstream from the balloon (22) and that this phenomenon is most likely due to sympathetic reflex pulmonary vasoconstriction (19,20).A prominent feature of this pulmonary artery distention reflex is its presumably positive feedback nature. The term "positive feedback" is used to describe this pulmonary vascular pressor reflex because it appears to depend on the excitation of stretch receptors upstream from the pulmonary vascular bed to cause the constriction of the downstream pulmonary vessels such that the greater the distention of the main pulmonary artery the greater the downstream vasoconstriction. Consideration of the implications and significance of the existence of such a pulmonary arterial stretch receptor system to raise pulmonary vascular resistance, via positive feedback mechanisms, as shown in the dog, poses the following questions: (I) is this pulmonary hypertension reflex present in other species? (2) is this reflex more active in the newbo...

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Section: Discussionmentioning

confidence: 85%

Pulmonary Arterial Hypertension Induced by Distention of the Main Pulmonary Artery in Conscious Newborn, Young, and Adult Sheep

et al. 1980

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“…PAH is characterised by typical angioproliferative lesions, such as neointimal lesions, leading to increased pulmonary vascular resistance 2. The elevated pulmonary vascular resistance leads to high right ventricle systolic pressure and subsequent right ventricular hypertrophy (RVH) ultimately resulting in heart failure 3 4.…”

Section: Introductionmentioning

confidence: 99%

Lung irradiation induces pulmonary vascular remodelling resembling pulmonary arterial hypertension

Ghobadi

Bartelds

Veen

et al. 2011

Thorax

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Background Pulmonary arterial hypertension (PAH) is a commonly fatal pulmonary vascular disease that is often diagnosed late and is characterised by a progressive rise in pulmonary vascular resistance resulting from typical vascular remodelling. Recent data suggest that vascular damage plays an important role in the development of radiation-induced pulmonary toxicity. Therefore, the authors investigated whether irradiation of the lung also induces pulmonary hypertension. Methods Different sub-volumes of the rat lung were irradiated with protons known to induce different levels of pulmonary vascular damage. Results Early loss of endothelial cells and vascular oedema were observed in the irradiation field and in shielded parts of the lung, even before the onset of clinical symptoms. 8 weeks after irradiation, irradiated volume-dependent vascular remodelling was observed, correlating perfectly with pulmonary artery pressure, right ventricle hypertrophy and pulmonary dysfunction. Conclusions The findings indicate that partial lung irradiation induces pulmonary vascular remodelling resulting from acute pulmonary endothelial cell loss and consequential pulmonary hypertension. Moreover, the close resemblance of the observed vascular remodelling with vascular lesions in PAH makes partial lung irradiation a promising new model for studying PAH.

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“…The ‘plexiform lesion’ is due to aneurysmal expansion of a sclerotic damaged vessel with associated minute abnormal vascular channels in the wall and is indicative of irreversible PAH (figure 1). 6 7 Proximal organised thrombi are found in over 50% of IPAH and are distinguished from the plexiform lesions by the presence of intact intima and elastic laminae.…”

Section: Idiopathic Pulmonary Arterial Hypertensionmentioning

confidence: 99%

Imaging in pulmonary hypertension, part 3: small vessel diseases

Gopalan¹,

McCann²,

Sheares³

et al. 2012

Postgrad Med J

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Pulmonary hypertension is a significant cause of morbidity and mortality. Unfortunately, non-specific presentation and lack of awareness of the disease frequently lead to significant delay in diagnosis, often with the onset of right heart failure, when prognosis is poor and therapy is of limited effectiveness. The classification of pulmonary hypertension is a clinical one grouping diseases into categories with similar patho-physiological mechanism and therapeutic options. Pulmonary biopsy can provide a definitive diagnosis but is hazardous in patients with pulmonary hypertension. Imaging has emerged as an invaluable tool in differentiating the aetiology, assessing disease severity and directing further management. One of the most important roles of imaging is to differentiate diseases resulting from obstruction of the large pulmonary arteries from those secondary to diffuse small vessel disease, as these have very different prognosis and are also treated differently. Small vessel diseases causing pulmonary arterial hypertension most commonly result from diffuse remodelling of the pulmonary arterioles. There are multiple causes of arteriolar remodelling which share similar histopathological, clinical and imaging features. In a subgroup of small vessel diseases causing pulmonary hypertension the predominant site of increased vascular resistance is at the level of the capillaries or venules. Correct diagnosis of pulmonary veno-occlusive disease and pulmonary capillary haemangiomatosis is essential since poor prognosis and inadvertent administration of vasodilators (conventional therapy for arteriolar predominant disease) can result in fatal pulmonary oedema. Multimodality imaging plays an important role in suggesting a diagnosis, guiding further investigation and directing treatment.

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Primary Pulmonary Hypertension

Abstract: SUMMARYMorphologic and morphometric studies were carried out on pulmonary vessels in lung tissue from 156 patients, for whom a diagnosis of primary pulmonary hypertension had been made. This

Cited by 491 publications

References 64 publications

Pulmonary Arterial Hypertension Induced by Distention of the Main Pulmonary Artery in Conscious Newborn, Young, and Adult Sheep

Pulmonary Arterial Hypertension Induced by Distention of the Main Pulmonary Artery in Conscious Newborn, Young, and Adult Sheep

Lung irradiation induces pulmonary vascular remodelling resembling pulmonary arterial hypertension

Imaging in pulmonary hypertension, part 3: small vessel diseases

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