Pulmonary Hypertension: Causes, Symptoms and Treatment
Pulmonary hypertension is an elevation of mean pulmonary artery pressure more than 25 mmHg at rest.
Pulmonary hypertension occurs when a disease elevates pulmonary arterial pressure above normal. To calculate pulmonary artery pressure you use the formula:
Pulmonary artery pressure=left atrial pressure added to (pulmonary flow * pulmonary vascular resistance).
Normal pulmonary artery systolic pressure at rest is 15–30 mm Hg with a mean pressure between 10 mm Hg and 18 mm Hg.
Any single factor or combination of factors that increases left atrial pressure, pulmonary flow, or resistance can cause pulmonary hypertension.
PH often is progressive, and if untreated, the right ventricle eventually becomes unable to support the circulation, resulting in significant morbidity and mortality.
This condition predominantly affects women, aged 20–30 yrs.
Pulmonary circulation is a low pressure, low-resistance system due to its large surface area, accommodating high blood flow during exercise.
In pulmonary hypertension, there is an increase in pulmonary vascular resistance that leads to an increase in the pulmonary systolic pressure to greater than 30 mm Hg or the mean pressure greater than 20 mm Hg.
Respiratory failure due to intrinsic pulmonary disease is the most common cause.
The Clinical Severity According To The New York Heart Association Classification.
This classification is based primarily on symptoms and functional status.
Pulmonary hypertension without limitation of physical activity.
No dyspnea, fatigue, chest pain, or near syncope with exertion.
Pulmonary hypertension with a slight limitation of physical activity.
No symptoms at rest but ordinary physical activity causes dyspnea, fatigue, chest pain.
Pulmonary hypertension with marked limitation of physical activity.
No symptoms at rest but less than ordinary activity causes dyspnea, fatigue, chest pain, or near syncope.
Pulmonary hypertension with an inability to perform any physical activity without symptoms.
Evidence of right heart failure.
Dyspnea and fatigue at rest and worsening of symptoms with any activity.
Vasoconstriction, vascular proliferation, thrombosis, and inflammation appear to underlie the development of PAH. In long-standing PH, intimal proliferation and fibrosis, medial hypertrophy, and in situ thrombosis characterize the pathologic findings in the pulmonary vasculature.
Vascular remodeling at earlier stages may be confined to the small pulmonary arteries. As the disease advances, intimal proliferation and pathologic remodeling progress, resulting in decreased compliance and increased elastance of the pulmonary vasculature. The outcome is a progressive increase in the right ventricular afterload or total pulmonary vascular resistance (PVR) and, thus, right ventricular work.
In subjects with moderate to severe pulmonary vascular disease with significantly increased PVR, as the resting PVR increases, there will be a corresponding increase in mean pulmonary artery pressure (PAP) until the cardiac output (CO) is compromised and starts to fall. With a decline in CO, the PAP will fall. As CO declines as a result of increased afterload and decreased contractility, tachycardia is a compensatory response.
Tachycardia decreases filling time and, thus, preload, and results in a reduced fraction of stroke
volume available to distend the pulmonary vascular tree.
In addition, thrombin deposition in the pulmonary vasculature from the prothrombotic state that develops as an independent abnormality or as a result of endothelial dysfunction may amplify
vascular cell proliferation and the obliterative arteriopathy
Clinical Presentation of Pulmonary Hypertension
There are no specific signs and symptoms to show pulmonary hypertension.
The patient will present with
- Exertional breathlessness
- Anginal pain,
- Nonproductive cough,
- Malaise, and fatigue
- Hemoptysis is a rare
Physical Examination Findings
During your physical examination you will realize:
- Jugular venous distention,
- Accentuated pulmonary valve component of the second heart sound,
- Right-sided third heart sound,
- Tricuspid regurgitation murmur,
- Lower extremity edema.
Diagnosis and Laboratory Findings
- Right-sided cardiac catheterization remains the gold standard.
- Arterial blood gas analysis is indicative of hyperventilation with a decrease in Paco2.
- Radiology CT Scan shows enlarged pulmonary arteries and
- Echocardiography with Doppler shows an enlarged right ventricle;
- Pulmonary function testing
- HIV and autoantibody testing.
- The electrocardiogram shows right axis deviation, incomplete right bundle branch block) and right atrial enlargement
- Ventilation Perfusion Scanning
- Pulmonary angiography
- Magnetic Resonance Imaging
Early treatment aimed at the underlying disease process may prevent progression. The prognosis is determined by the reversibility of the underlying disease process
Treatment of persistent pulmonary hypertension is aimed at preventing end-organ injury from hypoxia, ischemia, and barotrauma.
This goal is accomplished by correcting any contributing disturbances, including hypoglycemia, polycythemia, hypothermia, or pneumothorax while maintaining systemic resistance and selectively lowering pulmonary vascular resistance.
Systemic vascular resistance is maintained with volume (crystalloid or colloid) and inotropic (dopamine and dobutamine) support, aiming at a mid- to high-normal systemic blood pressure. Such therapy decreases the pulmonary-to-systemic pressure gradient and improves tissue oxygenation.
Pulmonary vascular resistance is lowered by administering generous concentrations of oxygen. For refractory hypoxemia, inhaled nitric oxide (iNO) may be administered, which activates soluble guanylate cyclase, increases cyclic guanosine monophosphate (cGMP) production, and activates a cascade causing calcium efflux, with resultant vascular smooth muscle relaxation.
First-line therapy consists of oral calcium channel blockers to patients with positive acute vasodilator.
For Group 1 patients in functional class II -oral endothelin receptor antagonists (ambrisentan, bosentan) and phosphodiesterase inhibitors (sildenafil, tadalafil).
For Group 1 patients in functional classes III and IV or Group 1 patients who are not responsive to previous therapies -prostanoid agents. Continuous long-term intravenous epoprostenol infusion.
Group 4 pulmonary hypertension (due to thromboembolic disease), long-term anticoagulation, Pulmonary thromboendarterectomy.
Heart-lung transplantation may be considered in selected patients
Diuretics, vaccination against infection.