5/98medslides.com1 pulmonary (arterial) hypertension
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5/98 MedSlides.com 1
Pulmonary (Arterial)
Hypertension
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Definitions
• Pulmonary arterial hypertension– acute (pulmonary embolism, ARDS)– chronic (clinically more common)
• Pulmonary venous hypertension– pulmonary venous (LA pressure) > 12 mmHg– Hallmarks: pulmonary congestion and edema– Invariably, PVH elicits PAH
• Cor Pulmonale– pulm HTN with RV hypertrophy and dilatation
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Survival as a Function of Mean Pulmonary Arterial Pressure
0
20
40
60
80
100
120
0 1 2 3 4 5
Years
% S
urv
ival <25
25-30
30-45
45+
Mean PAPressure
Prog Resp Res 1975, 9:10
mm Hg
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Pulmonary Circulation
• Before birth– pulmonary and systemic pressure are
equal in the order of 70/40 (mean 50)
• After birth– ductus arteriousus closes, lung expands,
PA pressure falls to 1/2 of systemic level– PA pressure gradually decrease over
weeks to reach adult level
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Pulmonary Circulation
• Pulmonary circulation is “protected” from being hypertensive– large capacity– great distensibility– low resistance– modest amounts of smooth muscle in the
small arteries and arterioles
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Pulmonary Hemodynamics
PA pressure (mmHg) 20/12, 15 38/14, 25
LA pressure (mmHg) 5.0 5.0
Cardiac Output 6 L/min 6 L/min
PVR (R Unit) 1.7 3.3
PVR = -------------------- ; CGS units = R units x 80PA - LA
Cardiac Output
Sea AltitudeLevel 15,000 ft
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Pulmonary Arterial Hypertensionpathophysiology
• Decrease in total cross-sectional area– lung resection
• Narrowing of the lumen of the small muscular arteries and arterioles resistance vessels (P = Q x R)– chronic hypoxia with vasoconstriction
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Primary or Idiopathic Pulmonary Hypertension
• Plexogenic
• Thromboembolic (small emboli)
• Veno-occlusive disease
• Pulmonary capillary hemangiomatosis
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Secondary Pulmonary Hypertension
• Hypoxic– chronic lung disease, sleep apnea
• Pulmonary Venous Hypertension– mitral stenosis, left ventricular failure
• Congenital Heart Disease– Eisenmanger’s, PDA, ASD, VSD
• Vascular Obstruction– thromboembolism, systemic vasculitis
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Evaluation
• Right heart catheterization– “gold standard” for the diagnosis of PH
• Chest Radiography– findings depends on the duration and etiology– enlargement of the pulmonary trunk and hilar
vessels, pruning of the peripheral tree, RV – hyperinflation, flattening of the diaphragm
• Electrocardiogram– RV enlargement
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Evaluation
• Ultrasound– assess RV wall thickness and function– estimate pulmonary pressure from TR jet
• Lung Scan– rule out pulmonary thromboembolic disease
• Radionuclide Studies– evaluate RV function
• Lung Biopsy– identify interstial or collagen vascular disease
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Evaluation
• Arterial blood gas• Pulmonary function test• Collagen vascular serology• Lower extremity venogram or compressive
ultrasonography• CBC and peripheral blood smear• Stool and urine for parasites• Polysomnogram
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Left-heartfailure
Congenitalheart disease
Increasedblood flow
Reversedshunt
Passive Pulm HTN
Abnormalvasoconstrictive
response
Hypoxemia
ErythrocytosisPulmonary Hypertension
RVH / Cor PulmonaleRV Failure
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Pulmonary Venous Hypertension
• Elevated LV diastolic pressure– LV systolic or diastolic failure– constrictive pericarditis
• Left atrial hypertension– mitral valve disease– Cor triatriatum– left atrial myxoma or thrombus
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Left ventricular failure
• LV failure is the most common cause of pulmonary hypertension
• LV failure is the most common cause of right ventricular failure - attributable to failure of the muscle in the shared ventricular septum
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Congenital Heart Disease
• Pulmonary hypertension is associated with many types of CHD, and often a major determinant of it’s clinical course
• Large left-to-right shunt ( blood flow)– atrial septal defect, ventricular septal
defect, patent ductus arteriosus• Right-to-left shunt ( vasomotor tone)
– hypoxia with in red cell mass
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LV-RV Inter-dependance Normal Heart
RV
LV ED Volume
ED
Pre
ssu
re RVLV
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LV-RV Inter-dependance Acute RV Distention
Dilated RV
Compressed“D” shaped LV
LVED VolumeL
VE
D P
ress
ure
Normal RV
Distended RV
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Thromboembolic Disease
• A form of occlusive pulm vascular disease– thromboembolic (U.S. and Europe)– schistosomiasis (Egypt)– filariasis (Asia)
• Categorization by arterial segment occlusion – small (attributable to organized thrombi)– intermediate (clots from upper legs and thighs)– large (chronic proximal thromboembolism)
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Respiratory Disease and Disorder
Chronic Lung Disease
PulmonaryHypertension
RV Dilatationand Hypertrophy
Hypoxia
Polycythemia
Restricted Pulmonary
Vascular Bed
HypercapniaAcidosis
RV Failure
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Respiratory Disease and Disorder
• Intrinsic disease of lung and/or airways• Interstitial fibrosis• Chronic obstructive lung disease• Conglomerate fibrosis, emphysema, and
chronic bronchitis• Collagen vascular disease • Alveolar hypoventilation (sleep apnea,
abnormal respiratory control, chest bellows)
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Miscellaneous Causes
• residence at high altitude
• hemoglobinopathies
• intravenous drug abuse
• alveolar proteinosis
• Takayasu’s disease
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References
• Hurst’s The Heart, 8th Edition,1994Schlant RC, Alexander RW, O’Rourke RA, Roberts R, Sonnenblick EH
• Hypoxia and pulmonary hypertension in chronic bronchitis.Bishop JM. Prog Resp Res 1975, 9:10