1.Pulmonary Vascular Disease 2.Pleural Disease

Prof. Frank Carey

Pulmonary Circulatuion

 Dual supply  Pulmonary arteries  Bronchial arteries  Low pressure system  Pulmonary artery receives entire cardiac output (a filter)

Low pressure system….

 Thin walled vessels  Low incidence of atherosclerosis At normal pressures

Pulmonary Oedema

 Accumulation of fluid in the lung  Interstitium  Alveolar spaces  Causes a restrictive pattern of disease

Pulmonary Oedema (causes)

1.

2.

Haemodynamic ( hydrostatic pressure) Due to cellular injury i.

Alveolar lining cells ii.

Alveolar endothelium Localised – pneumonia Generalised – adult respiratory distress syndrome (ARDS)

ARDS

 Diffuse alveolar damage syndrome (DADS)  Shock lung  Causes include sepsis, diffuse infection (virus, mycoplasma), severe trauma, oxygen

Pathogenesis of ARDS

Injury (eg bacterial endotoxin)  Infiltration of inflammatory cells  Cytokines  Oxygen free radicals  Injury to cell membranes

Pathology of ARDS

 Fibrinous exudate lining alveolar walls (hyaline membranes)  Cellular regeneration  Inflammation

ARDS with hyaline membrane

ARDS – cellular reaction

Outcome of ARDS

 Death  Resolution  Fibrosis (chronic restrictive lung disease

Neonatal RDS

 Premature infants  Deficient in surfactant (type 2 alveolar lining cells  Increased effort in expanding lung physical damage to cells

Embolus

 A detached intravascular mass carried by the blood to a site in the body distant from its point of origin  Most emboli are thrombi – others include gas, fat, foreign bodies and tumour clumps

Pulmonary Embolus

 Common  Often subclinical  An important cause of sudden death and pulmonary hypertension 95% + of emboli are thromboemboli

Source of most pulmonary emboli…..

 Deep venous thrombosis (DVT) of lower limbs

Risk factors for PE are those for DVT….

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2.

3.

Factors in vessel wall (eg endothelial hypoxia) Abnormal blood flow (venous stasis) Hypercoaguable blood (cancer patients, post-MI etc) - Virchow’s triad

Effects of PE

 Sudden death  Severe chest pain/dyspnoea/haemoptysis  Pulmonary infarction  Pulmonary hypertension

Effects of PE depend on…

 Size of embolus  Cardiac function  Respiratory function

Effect of embolus size…

 Large emboli    Death Infarction Severe symptoms  Small emboli   Clinically silent Recurrent pulmonary hypertension

Pulmonary Infarct (ischaemic necrosis)

 Embolus necessary but not sufficient  Bronchial artery supply compromised (eg in cardiac failure)

Pummonary Embolus

Pulmonary infarct – tumour embolus

Pulmonary Hypertension

 Primary (rare, young women)  Secondary

Pulmonary Hypertension (mechanisms)

 Hypoxia (vascular constriction)  Increased flow through pulmonary circulation (congenital heart disease)  Blockage (PE) or loss (emphysema) of pulmonary vascular bed  Back pressure from left sided heart failure

Morphology of pulmonary hypertension

 Medial hypertrophy of arteries  Intimal thickening (fibrosis)  Atheroma  Right ventricular hypertrophy  Extreme cases (congenital heart disease, primary pulmonary hypertension) – plexogenic change/necrosis

Pulmonary artery – intimal fibrosis

Plexiform lesion – primary pulmonary hypertension

“Cor Pulmonale”

 Pulmonary hypertension complicating lung disease  Right ventricular hypertrophy  Right ventricular dilatation  Right heart failure (swollen legs, congested liver etc)

Cardiomegaly due to right ventricular dilatation

Right ventricular hypertrophy and dilatation

The Pleura

 A mesothelial surface lining the lungs and mediastinum  Mesothelial cells designed for fluid absorption  Hallmark of disease is the effusion

Pleural Effusion

 Transudate (low protein)  cardiac failure  hypoproteinaemia  Exudate (high protein)     pneumonia TB connective tissue disease malignancy (primary or metastatic)

Pleural effusion

Purulent Effusion

Full of acute inflammatory cells  Empyema  Can become chronic

Pneumothorax

Air in pleural space  Trauma  Rupture of bulla

Large bullae

Pleural Neoplasia

 Primary  benign (rare)  malignant mesothelioma  Secondary  common (adenocarcinomas - lung, GIT, ovary)

Mesothelioma

 Asbestosis related  Increasing incidence  Mixed epithelial/mesenchymal differentiation  Dismal prognosis

Mesothelioma

Pleural biopsy - mesothelioma

Metastases in Pleura

Differential diagnosis of malignant effusions…..

 Cytology, biopsy  Difficult  Immunohistochemistry for lineage specific antigens may help  Medicolegal importance