Pulmonary vascular pathology Flashcards
Pulmonary embolism stem from where? they are usually what? Where do they go?
PE is usually venous in nature. They are typically (> 95% of the time) fragmented thrombi from deep venous thromboses (usually from lower legs) that progress through larger venous channels, travel through the right side of the heart, and then become dangerously trapped in the pulmonary arterial vasculature, where the vessels begin to narrow.
A large single embolus can straddle the pulmonary artery bifurcation (saddle embolus)
Embolus can lodge in a pulmonary artery main branch and cause one-sided disease
Most frequently, one or both sides of the lungs get showered with varying numbers of small emboli that lodge in the smallest arterioles possible
what does the image show?
A saddle embolus in an opened pulmonary artery, going into both the left and right main pulmonary arteries (arrows). The gross image is typical, showing areas that dark red admixed with paler regions, which will be seen as lines of Zahn on microscopy.
Most pulmonary embolism are what? Occur in who?
Most pulmonary emboli are clinically silent (60-80%), relatively small, and become incorporated/organized into the vascular wall. They occur in 2-4/1000 hospitalized patients, and are more common in older patients and/or those with certain underlying conditions (surgery, pregnancy, malignancy).
PE complications?
Still, PE causes roughly 200,000 deaths per year and other major complications can be seen in association:
Sudden cardiac death, right sided heart failure (cor pulmonale), or general cardiovascular collapse can occur when there is > 60% pulmonary circulatory obstruction
Embolism of medium-sized arteries can result in pulmonary hemorrhage, but not usually pulmonary infarction, due to the (dual) bronchial circulation
Embolism of small end-arteriolar pulmonary branches usually does not result in hemorrhage or infarction
Multiple emboli (over time) can cause pulmonary hypertension and right sided heart failure
Patients who have had one PE are at high risk for having another
explain the image?
In this lung image, a small vessel in undergoing both embolus (the redder intraluminal material) and organization (arrow). An organizing process appears like new or immature collagen that begins to incorporate the embolus into the wall/overall structure of the vessel.
Fat and marrow emboli occur when?
Following mechanical insult, there may be rupture of soft tissue venules or marrow vascular sinusoids. Adipose tissue or bone marrow can then herniate into these intravascular spaces and travel to lung, where they become lodged. Clinical scenarios when this might occur:
Vigorous cardiopulmonary resuscitation – likely no clinical consequence
Fracture of long bones – seen in 90% of individuals with severe skeletal injury, but less than 10% of these patients experience overt symptoms
Soft tissue trauma
Burn patients
what is a fat embolism? patients may experience?
Fat embolism syndrome is the name given to that situation in which fat emboli become symptomatic. After 1-3 days, patients may experience pulmonary insufficiency, neurologic symptoms, anemia, thrombocytopenia, and a diffuse petechial rash (in 20-50% of patients). This is fatal in 5-15% of patients.
what does the image show?
Image: Fat and bone marrow elements are present in a pulmonary vessel.
Explain air emboli?
Gas bubbles can coalesce within the circulation, forming frothy masses that can then obstruct distal vascular flow.
Generally, more than 100 cc (ml) of air is needed to have a clinical effect on pulmonary circulation, such as with obstetric procedures, laparoscopic procedures or chest wall injury.
Much smaller volumes can be catastrophic if introduced into the coronary circulation during coronary artery bypass surgery or into cerebral circulation during neurosurgery.
What is decompression sickness? Manifestations?
Decompression sickness can result when individuals experience a sudden decrease in atmospheric pressure. It is most commonly seen in scuba/deep sea divers, underwater construction workers, or individuals in unpressurized aircraft in rapid ascent. Physiologically, air breathed in at higher pressures causes more of the gas (particularly nitrogen) to be in solution in the blood and tissues. With a sudden decrease in pressure, the nitrogen comes out of solution and returns to a gaseous state, thereby causing air embolism.
the bends – the rapid formation of gas bubbles within skeletal muscles, supporting tissues, and around joints causes pain
the chokes – respiratory distress caused by pulmonary gas emboli leading to edema, hemorrhage, and focal atelectasis or emphysema
Caisson disease – chronic condition of decompression seen in underwater bridge workers where the persistence of gas emboli in the skeletal system leads to multiple foci of ischemic necrosis of the femoral heads, tibia, and humeri
Treatment of acute decompression sickness?
Treatment of acute decompression sickness includes methods of slower decompression such that gradual resorption and exhalation of gases will prevent emboli from forming. Examples include “safety stops” during scuba diving, or placing individuals in high pressure chambers in order to regulate the environment.
Pulmonary Hypertension is what?
Increased arterial pressure within the pulmonary circulation can be a different ‘kind’ of overall disease than hypertension which occurs systemically (somewhat analogous to portal hypertension in GI blood flow being different from systemic HTN). In any type of pulmonary HTN, vascular remodeling leads to progressive pulmonary dysfunction.
what are the categories of Pulmonary hypertension?
Pulmonary hypertensive changes can fit into three very broad (and arguably correct) categories:
As part of systemic, essential hypertension. Pulmonary vessels can be affected like vessels anywhere, however, other organ-based manifestations of systemic hypertension usually take precedence, such as changes occurring in the kidneys, retinas, cerebral vessels, heart, etc. Said another way, the pulmonary vascular changes in this setting are usually and relatively clinically ‘silent’ or mild, because the pulmonary vascular circuit is separate from systemic circulation both anatomically and physiologically.
As part of idiopathic pulmonary hypertension. This is an uncommon, isolated HTN affecting the pulmonary vessels usually with a genetic basis of inheritance. o Women > men, ages 20-40, present with dyspnea, fatigue, and cyanosis
As part of various cardio- or pulmonary structural disease. This is the important category, ranging from obstructive or interstitial lung disease, left heart failure, chronic hypoxia processes (such as recurrent thromboemboli), autoimmune disease, structural cardiac diseases (valvular disease, cardiomyopathies, etc.), etc…
What is the image showing?
A thickened pulmonary arteriole, showing medial hypertrophy and intimal fibrosis, to the point of almost obstructing the lumen.
Explain the image?
A plexiform lesion seen on elastic stain. These develop when capillary tufts bud off an arteriole, hook up to adjacent arterioles, and create complicated vascular amalgams. In this image, a couple of arterioles (with elastic in their walls) at the bottom are next to a proliferating capillary network (arrow, no elastic present).
explain the image?
image left: In Goodpasture syndrome, the lungs appear consolidated (thick) and heavy, and possibly hemorrhagic.
Image below: Type II pneumocytes will undergo hypertrophy and hyperplasia, alveolar spaces will be filled with hemorrhage, and hemosiderin-laden macrophages will become obvious as the red cells are recycled.
What is the major treatment for Goodpasture syndrome?
One major treatment for Goodpasture syndrome is apheresis (see schematic). The patient’s vascular system is hooked up so the following can occur: blood leaves the patient, it enters the apheresis unit (on the left), gets centrifuged, and splits into the red cell (bottom) layer, the white cell (middle) layer, and the plasma (upper) layer. Any layer can now be removed/manipulated/filtered for any purpose.
For Goodpasture syndrome, the plasma layer (on the right) is removed and filtered through a membrane that removes the autoantibody, and then this treated plasma is put back into the patient, completing the loop.
what does the image show?
Hemorrhage into alveolar spaces is now evident as hemosiderin-laden macrophages. The clinical and serologic features help separate this entity from Goodpasture syndrome, even if histologically they look similar.
