Pulmonary artery obstruction

III. Imaging Neovascularization after Pulmonary Artery Obstruction 371... 

Single photon emission computed tomography (SPECT) imaging of technetium 99m-labeled albumen aggregates can provide new insights into the distribution of blood how in this model of pulmonary artery obstruction. Recently, Clough et al. (27) and Wietholt et al. (28) used micro-CT coupled... 

Charan NB, Carvalho P. Angiogenesis in bronchial circulatory system after unilateral pulmonary artery obstruction. J Appl Physiol 1997 82 284- 291. 

Pulmonary embolism A disorder of thrombus formation causing obstruction of a pulmonary artery or one of its branches may result in pulmonary infarction. 

Venous thromboembolism (VTE) results from clot formation in the venous circulation and is manifested as deep vein thrombosis (DVT) and pulmonary embolism (PE). A DVT is a thrombus composed of cellular material (red and white blood cells, platelets) bound together with fibrin strands. A PE is a thrombus that arises from the systemic circulation and lodges in the pulmonary artery or one of its branches, causing complete or partial obstruction of pulmonary blood flow. 

Hypertrophic cardiomyopathy (IHSS) Serious adverse effects were seen in 120 patients with IHSS (especially with pulmonary artery wedge pressure more than 20 mm Hg and left ventricular outflow obstruction) who received oral verapamil at doses up to 720 mg/day. Sinus bradycardia occurred in 11%, second-degree AV block in 4% and sinus arrest in 2%. 

In the lungs, NO affects not only blood vessels but also the bronchi and bronchioles as well. In newborns with defective gas exchange, NO inhalation decreases pulmonary arterial blood pressure, enabling more blood to be oxygenated. In adults with obstructive lung diseases, NO inhalation seems to relax airway smooth muscle, thus acting as a bronchodilator. 

Almitrine is a respiratory stimulant that improves hypoxemia in about 80% of patients with severe chronic obstructive pulmonary disease (SEDA-17, 212). Oral almitrine bimesilate (100 mg/day) increased Pa02 in patients with severe chronic obstructive pulmonary disease without altering mean pulmonary artery pressure (1). Adverse effects were rarely observed and it was concluded that long-term treatment was safe. In other studies, respiratory, digestive, and neurological symptoms have been noted but were often pre-existent (2,3). 

An 81-year-old man underwent CT scanning of the head with intravenous contrast enhancement (100 ml of the non-ionic contrast medium iopamidol). After the injection he complained of sweating and nausea and had a cardiorespiratory arrest. Immediate resuscitation and intravenous dexamethasone and adrenaline were not successful. Mast cell tryptase activity in a sample taken 4 hours after death was high. At autopsy, the coronary and pulmonary arteries were patent. The right heart chambers were moderately enlarged. The lungs were hyperemic and edematous and there was obstructive edema of the larynx. 

The majority of patients with pulmonary hypertension are largely asymptomatic until marked vascular alterations have developed. When blood flow through the pulmonary artery is obstructed over a long period of time, however, the clinical picture is predictable and markedly uniform. In general, the patients exhibit normal pulmonary function measurements, a low carbon monoxide diffusion capacity (DlCO), and marked hyperventilation that leads to hypocapnia and decreased serum bicarbonate concentrations. Additional symptoms include weakness, fatigue, exertional dyspnea, and chest pains upon exertion due to low cardiac output and hypoxemia. Occasionally, hoarseness, hemoptysis, and cyanosis occur. 

FIGURE 7 Percentage changes in hemodynamic variables from baseline values during a 15-rain administration of inhaled nitric oxide in postoperative neonates with no residual anatomic obstruction to pulmonary blood flow. There was a marked pulmonary vasodilating effect. HR, Heart rate Cl, cardiac index BP, systemic artery pressure SVR, systemic vascular resistance PAP, mean pulmonary artery pressure PVR, pulmonary vascular resistance. 

FIGURE 8 Bedside monitor recording of pulmonary artery pressure (PAP) and systemic artery pressure (SAP) in a 1-day-old postoperative patient after repair of obstructed total anomalous pulmonary venous connection. Stable PAP and SAP are achieved with 15-ppm nitric oxide (NO). When the NO was transiently discontinued, there was a prompt increase in PAP and profound systemic hypotension. With reinstitution of NO, recovery occurred. Subsequently, the child was easily weaned from NO. 

Dinh-Xuan, A. T., Higenbottam, T. W., Clelland, C. A., et al. (1991). Impairment of endothelium-dependent pulmonary-artery relaxation in chronic obstructive lung disease. N. Engl. J. Med. 324, 1539-1547. 

In the event that a circulating clot enters the heart, it will circulate through the pulmonary artery to the lungs, where it will likely cause an obstruction in the capillary. Over time this may lead to pulmonary insufficiency, difficulty in breathing and chest pain, which are symptoms of pulmonary embolism (PE) (Figure 2). 

Fadel E, Riou JY, Mazmanian M et al. Pulmonary thromboendarterectomy for chronic thromboembolic obstruction of the pulmonary artery in piglets. J Thorac Cardiovasc Surg 1999 117 787 -793. 

Other rare vascular complications of sarcoidosis (limited to a few case reports) include pulmonary arterial stenoses from granulomatous involvement of the vessels, extrinsic compression of pulmonary arteries by enlarged hilar lymph nodes or fibrosing mediastinitis (6), pulmonary veno-occlusive disease (resulting from obstruction of interlobular septa veins by granulomata or perivascular... 

On lung examination, tachypnea and bibasUar dry crackles can be found in any clinical presentation of HP. Wheezing, provoked by small airway obstruction, is uncommon but when present, may lead to an erroneous diagnosis, i.e., asthma. Patients with chronic HP may develop digital clubbing, pulmonary arterial hypertension, and even cor pulmonale (1,38). 

Upper airway obstruction Epiglottitis and laryngitis Cricoar5ftenoid arthritis Bronchiectasis Bronchiolitis obliterans Shrinking lung syndrome Diaphragmatic dysfunction Pulmonary vascular disease Thromboembolic disease Pulmonary arterial hypertension Mediastinal and axillary lymphadenopathy... 

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