The lungs in heart disease

The Regulation of Pulmonary Vascular Tone by Neuropeptides and the Implications for Pulmonary Hypertension

Pulmonary hypertension (PH) is an incurable, chronic disease of small pulmonary vessels. Progressive remodeling of the pulmonary vasculature results in increased pulmonary vascular resistance (PVR). This causes secondary right heart failure. PVR is tightly regulated by a range of pulmonary vasodilators and constrictors. Endothelium-derived substances form the basis of most current PH treatments. This is particularly the case for pulmonary arterial hypertension. The major limitation of current treatments is their inability to reverse morphological changes. Thus, there is an unmet need for novel therapies to reduce the morbidity and mortality in PH. Microvessels in the lungs are highly innervated by sensory C fibers. Substance P and calcitonin gene-related peptide (CGRP) are released from C-fiber nerve endings. These neuropeptides can directly regulate vascular tone. Substance P tends to act as a vasoconstrictor in the pulmonary circulation and it increases in the lungs during experimental PH. The receptor for substance P, neurokinin 1 (NK1R), mediates increased pulmonary pressure. Deactivation of NK1R with antagonists, or depletion of substance P prevents PH development. CGRP is a potent pulmonary vasodilator. CGRP receptor antagonists cause elevated pulmonary pressure. Thus, the balance of these peptides is crucial within the pulmonary circulation (Graphical Abstract). Limited progress has been made in understanding their impact on pulmonary pathophysiology. This is an intriguing area of investigation to pursue. It may lead to promising new candidate therapies to combat this fatal disease. This review provides a summary of the current knowledge in this area. It also explores possible future directions for neuropeptides in PH.

Diagnosis and management of pulmonary hypertension over the past 100 years

Pulmonary hypertension is a rare disease with a poor prognosis. It was first described in the late 19th century as a clinical-pathological syndrome characterised by obstruction of the small pulmonary arteries and right ventricular hypertrophy in patients presenting with severe dyspnoea and cyanosis. After the development of right heart catheterisation in the second half of the 20th century, it was found that many diseases could cause pulmonary hypertension, which is now recognised to be high blood pressure in the arteries that supply the lungs. In the 1960s, an epidemic of pulmonary hypertension caused by appetite suppressants initiated a systematic collection of information on pulmonary hypertension, leading to the first international classification of pulmonary hypertension. Increased understanding of the pathogenesis of the various forms of pulmonary hypertension has led to novel treatments and holds promise for the future.

Tomographic Evaluation of Hemodynamic Changes in Mitral Stenosis

The hemodynamic findings in 31 patients with mitral valvular disease were correlated with the signs obtained by chest tomography. The normal and pathologic findings are described. The advantages of the tomographic technic for the study of the pulmonary vasculature are pointed out.

The progression of mitral valve narrowing was considered to be best related to the integrated picture of "impaired venous drainage." On this basis, three stages were defined.

The over-all response of the pulmonary circulation to the severity of the disease can be judged by the pattern of blood vessels filling throughout the lung.

It is concluded that for the evaluation of mitral valvular disease routine tomographic technic can indicate many of the essential hemodynamic findings with less hazard than either angiography or cardiac catheterization.