Pulmonary Vascular Disease Flashcards
Definition of Pulmonary HTN
This term is used to encompass what two entities?
The term PAH is generally reserved for what WHO class entity?
PAH is defined as what pulmonary artery systolic pressure?
Elevated pulmonary venous pressures are present with what PCWP?
- Clinically, the term pulmonary hypertension is used to encompass both pulmonary arterial and pulmonary venous hypertension. The term pulmonary arterial hypertension (PAH) is generally reserved for the WHO class 1 entities.
- It may be clinically difficult to distinguish pulmonary arterial from pulmonary venous hypertension. Further complicating the distinction, venous hypertension may be a cause of arterial hypertension.
- Pulmonary arterial hypertension is defined as pulmonary arterial systolic pressure >25 mm Hg at rest or >30 mm Hg during exercise.
- Elevated pulmonary venous pressures are present when pulmonary capillary wedge pressure (an approximation of pulmonary venous pressure) is >18 mm Hg.
What is the hemodynamic division of pulmonary hypertension?
Describe what is included in each division.
- Precapillary and postcapillary etiologies
- In precapillary causes of pulmonary hypertension, the primary abnormality is either the pulmonary arterial system or pulmonary arterial blood flow. Abnormalities of the pulmonary parenchyma leading to chronic alveolar hypoxia are also included in this category.
- In postcapillary causes of pulmonary hypertension, an abnormality of the pulmonary veins or elevation of pulmonary venous pressure leads to pulmonary arterial hypertension.
What is the WHO classification of PAH?
Describe each group and what is included in them.
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Group 1: Pulmonary arterial hypertension.
- Primary pulmonary hypertension (PPH) may be idiopathic or familial.
- Congenital left-to-right shunts, such as atrial septal defect (ASD) and ventricular septal defect (VSD), may cause PAH and shunt reversal (Eisenmenger syndrome).
- PAH may be caused by pulmonary venous or capillary involvement, such as pulmonary venoocclusive disease and pulmonary capillary hemangiomatosis.
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Group 2: Pulmonary venous hypertension.
- Left-sided heart disease (left atrial, left ventricular, or mitral/aortic valve disease) may cause elevated pulmonary venous pressure in chronic disease.
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Group 3: Pulmonary hypertension associated with chronic hypoxemia.
- COPD, interstitial lung disease, and sleep apnea can cause pulmonary hypertension in chronic disease.
- Group 4: Pulmonary hypertension due to chronic thromboembolic disease.
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Group 5: Pulmonary hypertension due to miscellaneous disorders.
- Sarcoidosis is a rare cause of pulmonary hypertension.
- Compression of pulmonary vessels, which can be due to neoplasm, fibrosing mediastinitis, etc., may cause pulmonary hypertension.
General Imaging of Pulmonary HTN
A main PA diameter of _____ cm suggest presence of PAH? What is another suggestive finding?
What is pathagnomonic for chronic PAH?
Mosaic attenuation is most commonly seen in what kind of pulmonary HTN?
How about ground glass centrilobular nodules?
What is the hilum convergence sign and why is it helpful?
What is the hilum overlay sign? What does it indicate?
- A main pulmonary artery diameter >2.9 cm suggests the presence of pulmonary hypertension, although pulmonary hypertension may be present in a normal caliber pulmonary artery. A main pulmonary artery diameter larger than the aortic root diameter is also suggestive of pulmonary hypertension.
- Pulmonary artery calcifications are pathognomonic for chronic pulmonary artery hypertension.
- Pulmonary hypertension may cause mosaic attenuation due to perfusion abnormalities, most commonly seen in chronic thromboembolic pulmonary hypertension (CTEPH).
- Pulmonary hypertension may be associated with ground glass centrilobular nodules, especially in pulmonary veno-occlusive disease.
- An enlarged pulmonary artery can mimic a mediastinal mass. The hilum convergence sign is helpful to confirm that the apparent “mass” in fact represents the pulmonary artery. The hilum convergence sign describes the appearance of hilar pulmonary artery branches converging into an enlarged pulmonary artery.
- In contrast, the hilum overlay sign describes the visualization of hilar vessels through a mass. It indicates that a mediastinal mass is present, which cannot be in the middle mediastinum. Usually, this means the mass is in the anterior mediastinum.
Primary Pulmonary HTN (PPH)
What WHO group is this?
Pre or postcapillary?
Pathologic hallmark? What’s up with prostacyclines and Nitric oxide?
Causes?
Imaging?
- WHO Group 1
- Precap
- The pathologic hallmark of primary pulmonary hypertension is the plexiform lesion in the wall of the muscular arteries, which is a focal disruption of the elastic lamina by an obstructing plexus of endothelial channels. There is a relative paucity of prostacyclins and nitric oxide expressed by endothelial cells.
- PPH may be idiopathic (females > males) or familial (approximately 10% of cases).
- On imaging, there is typically enlargement of the main pulmonary arteries with rapidly tapering peripheral vessels.
Pulmonary HTN due to Left-to-Right Cardiac Shunts
WHO classification?
Pre or postcapillary?
What are some examples?
What does it lead to? What is it called with their is reversal of congenital shunt?
Imaging appearance?
- WHO Group 1
- Precapillary
- Congenital left-to-right cardiac shunts, such as ventricular septal defect, atrial septal defect, and partial anomalous pulmonary venous return, cause increased flow through the pulmonary arterial bed. This chronically increased flow may eventually lead to irreversible vasculopathy characterized by pulmonary hypertension and reversal of the congenital shunt, known as Eisenmenger syndrome.
- Imaging of PAH secondary to a congenital shunt is similar to that of PPH. There is enlargement of the central and main pulmonary arteries, with peripheral tapering.
Pulmonary Veno-Occlusive Disease
WHO classification?
Pre or postcapillary?
What is it caused by?
Possible associations?
Imaging?
- WHO Group 1
- Precapillary
- PAH secondary to pulmonary veno-occlusive disease is caused by fibrotic obliteration of the pulmonary veins and venules. Pulmonary veno-occlusive disease may be idiopathic but is associated with pregnancy, drugs (especially bleomycin), and bone marrow transplant.
- Imaging features pulmonary arterial enlargement. Pulmonary edema and ground glass centrilobular nodules are often present.
Pulmonary Venous HTN
WHO grade?
Pre or postcapillary?
Physiology?
What are some examples?
- WHO group 2 - Pulm HTN due to left-sided heart disease
- Postcapillary
- Left-sided cardiovascular disease leads to elevated pulmonary venous pressure, which is a cause of pulmonary hypertension.
- Any left-sided lesion may cause pulmonary venous hypertension, including left ventricular oufllow tract lesions, mitral stenosis, and obstructing intra-atrial tumor/thrombus.
Pulmonary HTN Associated with Hypoxemic Lung Disease
WHO group?
Pre or postcapillary?
Causes?
Pathophysio?
What else does chronic lung dz do to pulmonary microvasculature?
- WHO Grade 3
- Precapillary
- COPD, sleep apnea, and interstitial lung disease can all lead to pulmonary hypertension.
- Chronic hypoxic vasoconstriction is thought to invoke vascular remodeling leading to hypertrophy of pulmonary arterial vascular smooth muscle and intimal thickening.
- Chronic lung disease can further contribute to the obliteration of pulmonary microvasculature through emphysema and the perivascular fibrotic changes of pulmonary fibrosis.
Chronic Thromboembolic Pulmonary HTN
WHO Classification?
Pre or postcapillary?
What percent of patients with PE get this?
What is the first step in the workup of a newly diagnosed pHTN?
Characteristic imaging features?
What can it do to bronchial arteries?
Treatment?
- WHO Grade 4
- Precapillary
- Chronic occlusion of the pulmonary arterial bed can lead to pulmonary arterial hypertension, which is a complication affecting 1-5% of patients who develop acute pulmonary embolism. Due to the high prevalence of PE, a PE-protocol CT is typically the first step in the workup of newly diagnosed pulmonary hypertension.
- Characteristic imaging features are peripheral, eccentric filling defects (in contrast to acute emboli which tend to be central) in the pulmonary arterial tree. Fibrous strands are sometimes visible on cross-sectional imaging. Mosaic perfusion may be present.
- CTEPH may cause secondary corkscrew bronchial arteries that are tortuous and dilated.
- Treatment of CTEPH is surgical thromboendarterectomy (similar to carotid endarterectomy).
Fibrosing Mediastinitis
WHO Classification
Pre or postcapillary?
What are the most common causes?
What does fibrous encasement of pulmonary veins lead to?
What about in the arteries?
Imaging?
- WHO group 5
- Pre or Post
- Progressive proliferation of fibrous tissue within the mediastinum may lead to encasement and compression of mediastinal structures. The most common causes of fibrosing mediastinitis are histoplasmosis and tuberculosis.
- Fibrous encasement of the pulmonary veins leads to permanent histological changes within the endothelial cells.
- Fibrosing mediastinitis may also encase the pulmonary arteries, creating a precapillary pulmonary hypertension.
- Imaging features of fibrosing mediastinitis include increased mediastinal soft tissue, often with calcified lymph nodes due to prior granulomatous infection.
Clinical Dx of Pulmonary Embolus
Why is the diagnosis challenging?
Where do most PE originate?
What are the risk factors?
What percent of patients with PE don’t have any identifiable risk factors?
What is the Wells score?
Talk about D-dimer.
- Diagnosis of pulmonary embolism can be challenging because the presenting symptoms are both common and nonspecific, including dyspnea, tachycardia, and pleuritic chest pain.
- Most pulmonary emboli originate in the deep veins of the thighs and pelvis. The risk factors for deep venous thrombosis are widely prevalent in a hospital environment, including:
- Immobilization, malignancy, catheter use, obesity, oral contraceptive use, and thrombophilia.
- Approximately 25% of patients with PE don’t have any identifiable risk factor.
- The Wells score assigns point values to clinical suspicion and various symptoms suggestive of pulmonary embolism.
- D-dimer is sensitive for thromboembolic disease and has a high negative predictive value, but is of little value in the typical inpatient population as there are many false positives.
What is the most common imaging method for detecting PEs?
Appearance of PE? Where do they tend to lodge?
An eccentric, circumferential filling defect suggests what?
What are some associated pulmonary abnormalitis commonly seen in patients with PEs? Are these specific?
- CT pulmonary angiogram is the most common method to image for PE, where an embolism is typically seen as a central intraluminal pulmonary artery filling defect. Pulmonary emboli tend to lodge at vessel bifurcations.
- An eccentric, circumferential filling defect suggests chronic thromboembolic disease.
- Associated pulmonary abnormalities are commonly seen in patients with PE, including wedge-shaped consolidation, pleural effusion, and linear bands of subsegmental atelectasis. These findings, however, are nonspecific. In particular, pleural effusions and consolidation are seen approximately equally in patients with or without pulmonary embolism.
What are the plain radiographic sign that could suggest PE?
- While a CT pulmonary angiogram is the standard tool to evaluation for pulmonary embolism, it is important to be aware of plain film findings that could suggest pulmonary embolism in case the diagnosis is not clinically suspected.
- The Fleischner sign describes widening of the pulmonary arteries due to clot.
- Hampton’s hump is a peripheral wedge-shaped opacity representing pulmonary infarct.
- Westermark sign is regional oligemia in the lung distal to the pulmonary artery thrombus.
Cardiac Evaluation in PE
Why must one always examine the heart after evaluating the pulmonary tree?
What can a massive PE due to the heart?
What is linearly correlated with increased mortality?
- Pulmonary embolism may cause acute right heart strain. After evaluation of the pulmonary arterial tree, one should always examine the heart for imaging findings of right heart dysfunction.
- Massive PE may cause acute right ventricular dilation with bowing of the intraventricular septum to the left. An elevated RV:LVratio (caused by RV enlargement) is linearly correlated with increased mortality.
