Pulmonary Circulation 2

Question 1

What is pulmonary hypertension?

Answer 1

Mean pulmonary artery pressure greater than 25 mmHg

(normal is 15-18 mmHg)

Question 2

What can cause an increase in pulmonary artery pressure?

Answer 2

1. Increased pulmonary vascular resistance
2. Increased left atrial pressure
3. Increased cardiac output (rarely by itself)

PAP - LAP = CO x PVR

PAP = (CO x PVR) + LAP

Question 3

What are the 2 kinds of pulmonary hypertension?

Answer 3

1. Pre-capillary pulmonary hypertension (pulmonary arterial hypertension) - PCWP is less than or equal to 15 mm Hg
2. Post-capillary pulmonary hypertension (pulmonary venous hypertension) - PCWP is greater than 15 mm Hg (this includes the left atrial pressure so if you have a problem with the mitral valve, you can have post-capillary pulmonary (venous) hypertension)

Question 4

Answer 4

B. WHO Group 2 Pulmonary Hypertension due to left heart disease (because PCWP is greater than 15 mmHg)

Question 5

What are 3 causes of acute pulmonary hypertension?

Answer 5

1. Pneumonia (hypoxic vasoconstriction)
2. Hypoxia (high altitude)
3. Thromboembolic disease

Question 6

What are the risk factors for DVT?

Answer 6

Virchow’s Triad:

• Trauma
• Stasis
• Hypercoaguability

Question 7

Pulmonary Embolisms result in ____ _____ strain/failure which leads to increased _______ and decreased ______.

Answer 7

Right ventricle strain (“submassive”) or failure (“massive”), increased myocardial O₂ demand, decreased myocardial O₂ delivery.

This cycle leads to death

Question 8

What is Wells’ DVT Score?

Answer 8

It’s a score that is given depending on clinical features that cause risk for DVT.

Question 9

What is the Wells’ PE Score?

Answer 9

This uses clinical features to predict probability of developing a PE.

Question 10

How do you diagnose PE?

Answer 10

History and physical (e.g. Wells’ scores)

D-dimer (breakdown products of thrombin)

ECG

CXR

V/Q scan

CT angiogram

Angiogram

Echocardiography

Question 11

What ECG findings are typically seen for PE?

Answer 11

Classic finding but less often seen is SI, QIII, TIII (prominant S wave in lead I, prominant Q wave and inverted T wave in lead III)

Most commonly seen is sinus tachycardia

Question 12

What is CXR like on patients with PE?

Answer 12

CXR is typically normal but it is used to exclude other processes.

A couple findings that can sometimes be found are Hamptom’s Hump (showing infarcted area of lung) or Westermark’s sign (showing hypoperfusion of a lung–the lung is more translucent than usual)

Question 13

What is V/Q scan and how is it used to detect PE?

Answer 13

V/Q scan is a nuclear medicine scan that can visualize ventilation vs. perfusion. The patient inhales an agent while taking another through IV and the ventilation scans are compared with perfusion to see if they match. In a patient with PE, they will have mismatch defects that often look like wedges.

Question 14

How is CT angiography used to diagnose PE?

Answer 14

A contrast agent is given and when visualized on CT you can see where blockages are. In this image, you can see the gray area that is blocked

Question 15

How is an angiogram used to diagnose PE?

Answer 15

This is rarely performed these days but used to be gold standard. It is done by inserting a catheter into the pulmonary vessel and you shoot die in to look for occlusions and defects

Question 16

How do you treat Stable (“submassive”) PE? (3)

Answer 16

Parenteral anticoagulation (heparin unfractionated or LMWH)

Catheter directed thrombolysis (tPA)

Oral anticoagulation (warfarin)

Question 17

How do you treat unstable (“massive”) PE?

Answer 17

These patients are hypotensive and have RV failure.

• Heparin
• Thrombolysis (tPA) (this can be risky as it causes bleeding but it is used since this is an emergency situation)
• IVC Filter (prevents further clots from coming up the leg)
• Surgical thrombectomy

Question 18

Answer 18

B. A large infiltrate on chest x-ray

You would expect to find an incompressible deep vein in the leg on ultrasound, you would expect to find an elevated plasma d-dimer, and you would expect an intraluminal filling defect on CT chest with contrast. However, you would not expect anything in the lung fields.

Question 19

What are the 5 WHO groups for pulmonary hypertension?

Answer 19

1. Pulmonary arterial hypertension
2. PH due to left heart disease
3. PH due to lung diseases and/or hypoxia
4. Thromboembolic pulmonary hypertension
5. PH with unclear/multifactorial mechanisms

Question 20

Which pulmonary hypertension WHO groups are in the pulmonary arterioles vs pulmonary venous system?

Answer 20

Pulmonary arterial hypertension, Pulmonary hypertension due to lung diseases and/or hypoxia, and thromboembolic pulmonary hypertension (classes 1, 3, and 4) are typically in the pulmonary arterioles.

Pulmonary hypertension due to left heart disease (class 2) is found in the pulmonary venous system.

Class 5, miscellaneous (sarcoidosis, LAM, etc) is variable.

Question 21

Pulmonary hypertension is defined by having a mean PAP greater than or equal to 25 mmHg. What is the definition for pulmonary arterial hypertension (PAH)?

Answer 21

Mean PAP greater than or equal to 25 mmHg AND

PCWP/LVEDP less than or equal to 15 mmHg AND

PVR is greater than 3 wood units

Question 22

What is idiopathic pulmonary arterial hypertension?

Answer 22

This a rare and fatal form of pulmonary arterial hypertension that is paradigmatic of WHO Group 1 Disease.

It affects young women preferentially (3:1 F:M) and usually occurs in 3rd and 4th decades of life. The incidence is 1 per million per year and the median survival without treatment is 2.8 years and with treatment is 7 years.

Question 23

Interpret this diagram

Answer 23

As pulmonary arterial hypertension progresses, the cardiac output starts to fail. Once the cardiac output fails, the pulmonary arterial pressure also falls because the heart is unable to overcome the increasing pulmonary vascular resistance. Also notice that there is a rise in BNP starting around NYHA 3 that is released during heart failure.

Question 24

What does CXR look like for pulmonary arterial hypertension as the disease progresses?

Answer 24

As you get decreased perfusion to the lungs, the lung fields start to look more transparent. Also, the cardiac silhouette gets larger and larger.

Question 25

What is the physical exam like for pulmonary arterial hypertension?

Answer 25

Distended neck veins

Lung auscultation is normal (no rales)

Cardiac exam had a loud P2, murmur of the tricuspid regurgitation

Edema in extremeties

Question 26

How do you treat pulmonary arterial hypertension?

Answer 26

Treat underlying cause (liver disease, HIV, etc)

Correct hypoxia (supplement oxygen)

Control intravascular volume status (limit fluid intake, limit sodium intake, diuresis)

Anticoagulation (?)

Pulmonary vasodilators

Lung transplantation

Question 27

What are the key treatment target pathways in pulmonary arterial hypertension? What are some drugs in these categories?

Answer 27

1. Endothelin pathway (endothelin receptor antagonists: bosentan, ambrisentan, macitentan)
2. Nitric oxide pathway (phosphodiesterase-5 inhibitors: sildenafil, tadalafil; soluble guanylate cyclase stimulator: riociguat)
3. Prostacyclin pathway (prostacyclin analogs: epoprostenol, treprostinil, selexipag)

Question 28

Answer 28

D. Obtain a right heart catheterization

You need to diagnose the pulmonary arterial hypertension before you start sildenafil.

Question 29

Answer 29

B. Start a pulmonary vasodilatory like sildenafil.

You wouldn’t do a heparin drip because the V/Q scan was negative so there is no blood clot. You wouldn’t do a surgical lung biopsy or lung transplant evaluation (not severe enough for transplant)

Question 30

Answer 30

D. lung transplant evaluation

V/Q is still negative so no need for heparin.

IV fluids would cause a problem because these patients are volume sensitive and get overloaded easily (must watch sodium and water intake).

This patient is at the bad part of the pulmonary hypertension curve where the PVR is rising and the CO is falling.

Question 31

What is chronic thromboembolic disease (WHO Group 4 disease) and how is it treated?

Answer 31

About 3% of patients who have an acute PE develop CTEPH where the blood clot scars into the lung. In this patient, you can give blood thinners, tPA, etc which will prevent further clots but it won’t resolve the fibrous material from the scar that is causing the hypertension. Curative therapy for this is surgical pulmonary endarterectomy followed by long-term anticoagulation.

Question 32

Answer 32

D. Refer for pulmonary endartectomy

The patient is already on warfarin so there is no need to do heparin drip or tPA. The wedge pressure is not elevated so there isn’t a volume problem–no need for diuretics. This patient would most likely benefit from surgical pulmonary endartectomy (typical treatment for WHO group 4 chronic thromboemboli disease)

Question 33

How do you treat pulmonary venous hypertension?

Answer 33

• Decrease intravascular filling (limit fluid intake, limit sodium intake, diuresis)
• Improve LV contractility (decrease LV afterload by controlling systemic hypertension)
• Correct causes of LV failure (ischemia, valvular disease)

Do not use PAH specific therapy for PVH

Question 34

True or False: You can use PAH specific therapy for PVH

Answer 34

FALSE! DO NOT USE PAH SPECIFIC THERAPY FOR PVH

Treating them with PAH specific therapy will cause pulmonary edema. If you vasodilate on the arterial side, there will be increased blood flow into the capillaries but the fluid will be stuck in the capillaries because the hypertension is still present in the venous side. This increased pressure causes pulmonary edema.

Question 35

Answer 35

B. Start diuretics

High wedge pressure means you should give diuretics