Cor pulmonale

Cor pulmonale is defined as an alteration in the structure and function of the right ventricle caused by a primary disorder of the respiratory system. Pulmonary hypertension is the common link between lung dysfunction and the heart in cor pulmonale. Right-sided ventricular disease caused by a primary abnormality of the left side of the heart or congenital heart disease is not considered cor pulmonale, but cor pulmonale can develop secondary to a wide variety of cardiopulmonary disease processes. Although cor pulmonale commonly has a chronic and slowly progressive course, acute onset or worsening cor pulmonale with life-threatening complications can occur.
Pathophysiology: Several different pathophysiologic mechanisms can lead to pulmonary hypertension and, subsequently, to cor pulmonale. These pathogenetic mechanisms include (1) pulmonary vasoconstriction due to alveolar hypoxia or blood acidemia; (2) anatomic compromise of the pulmonary vascular bed secondary to lung disorders, eg, emphysema, pulmonary thromboembolism, interstitial lung disease; (3) increased blood viscosity secondary to blood disorders, eg, polycythemia vera, sickle cell disease, macroglobulinemia; and (4) idiopathic primary pulmonary hypertension. The result is increased pulmonary arterial pressure.
The right ventricle (RV) is a thin-walled chamber that is more a volume pump than a pressure pump. It adapts better to changing preloads than afterloads. With an increase in afterload, the RV increases systolic pressure to keep the gradient. At a point, further increase in the degree of pulmonary arterial pressure brings significant RV dilation, an increase in RV end-diastolic pressure, and circulatory collapse. A decrease in RV output with a decrease in diastolic left ventricle (LV) volume results in decreased LV output. Since the right coronary artery, which supplies the RV free wall, originates from the aorta, decreased LV output diminishes blood pressure in the aorta and decreases right coronary blood flow. This is a vicious cycle between decreases in LV and RV output.
Right ventricular overload is associated with septal displacement toward the left ventricle. Septal displacement, which is seen in echocardiography, can be another factor that decreases LV volume and output in the setting of cor pulmonale and right ventricular enlargement. Several pulmonary diseases cause cor pulmonale, which may involve interstitial and alveolar tissues with a secondary effect on pulmonary vasculature or may primarily involve pulmonary vasculature. Chronic obstructive pulmonary disease (COPD) is the most common cause of cor pulmonale in the United States.
Cor pulmonale usually presents chronically, but 2 main conditions can cause acute cor pulmonale: massive pulmonary embolism (more common) and acute respiratory distress syndrome (ARDS). The underlying pathophysiology in massive pulmonary embolism causing cor pulmonale is the sudden increase in pulmonary resistance. In ARDS, 2 factors cause RV overload: the pathologic features of the syndrome itself and mechanical ventilation. Mechanical ventilation, especially higher tidal volume, requires a higher transpulmonary pressure. In chronic cor pulmonale, right ventricular hypertrophy (RVH) generally predominates. In acute cor pulmonale, right ventricular dilatation mainly occurs.
Frequency:
In the US: Cor pulmonale is estimated to account for 6-7% of all types of adult heart disease in the United States, with chronic obstructive pulmonary disease (COPD) due to chronic bronchitis or emphysema the causative factor in more than 50% of cases. Although the prevalence of COPD in the United States is about 15 million, the exact prevalence of cor pulmonale is difficult to determine because it does not occur in all cases of COPD and the physical examination and routine tests are relatively insensitive for the detection of pulmonary hypertension. In contrast, acute cor pulmonale usually is secondary to massive pulmonary embolism. Acute massive pulmonary thromboembolism is the most common cause of acute life-threatening cor pulmonale in adults. In the United States, 50,000 deaths are estimated to occur per year from pulmonary emboli and about half occur within the first hour due to acute right heart failure.
Internationally: Incidence of cor pulmonale varies among different countries depending on the prevalence of cigarette smoking, air pollution, and other risk factors for various lung diseases.
Mortality/Morbidity: Development of cor pulmonale as a result of a primary pulmonary disease usually heralds a poorer prognosis. For example, patients with COPD who develop cor pulmonale have a 30% chance of surviving 5 years. However, whether cor pulmonale carries an independent prognostic value or it is simply reflecting the severity of underlying COPD or other pulmonary disease is not clear. Prognosis in the acute setting due to massive pulmonary embolism or ARDS has not been shown to be dependent on presence or absence of cor pulmonale.

Gastrointestinal Duplications

Gastrointestinal duplications are rare congenital malformations that may vary greatly in presentation, size, location, and symptoms.
Problem
In 1733, Calder published the first report of an intestinal duplication. In 1937, Ladd introduced the term duplication of the alimentary tract. This condition consists of a group of congenital anomalies with the following 3 characteristics:
A well-developed coat of smooth muscle is present.
The epithelial lining represents some portion of the alimentary tract.
Duplications are frequently intimately attached to some portion of the gastrointestinal tract.

Frequency
Gastrointestinal duplications are observed in 1 of every 4500 autopsies, predominantly in white males. The small intestine is the most frequent site involved, whereas gastric, duodenal, rectal, and thoracoabdominal involvement is relatively rare. Synchronous gastrointestinal duplications occur in as many as 15% of patients.
Cervical duplications: Cervical esophageal duplication cysts are the most unusual gastrointestinal duplication, with fewer than 10 cases reported.
Thoracic and thoracoabdominal duplications: These make up 4% of all gastrointestinal duplications.
Gastric duplications: These duplications account for 7% of all gastrointestinal duplications.
Pyloric duplications: These are extremely rare. However, they are reported in the literature.1
Duodenal duplications: These account for 5% of all gastrointestinal duplications.
Small-intestine duplications: The small intestine is the most frequent site of gastrointestinal duplications, accounting for 44% of cases.
Colonic duplications: They may be cystic or tubular; colonic duplications represent 15% percent of duplications.
Rectal duplications: These represent up to 5% of gastrointestinal duplications.

Etiology
The true etiology of gastrointestinal tract duplications is not known. Several theories have been postulated. The idea that the initial developmental abnormality occurs in the gastrulation stage and results in a split notochord has been proposed. During early embryogenesis, the notochord is open, and the endoderm of the yolk sac and the ectoderm of the notochord are fused; a tube called the neuroenteric canal connects the yolk sac and the amnion. As part of the development of the split notochord, an endodermal-ectodermal adhesion between the cord has been proposed to result in the persistence of an endomesenchymal tract between the yolk sac and the amnion. The endomesenchymal tract formed is responsible for the anomalies of the entire gastrointestinal system. However, not all duplications are compatible with this theory, and other etiologies have been proposed.
Some duplications of the foregut and hindgut may occur as a result of "partial twinning." These duplications may be associated with other paired structures, such as those found in the genital and urinary tract. Other duplications, especially those of the ileum, may occur as a result of persistent embryological diverticula. Some portions of the intestinal tract have a solid stage during development; therefore, duplications of these structures may result from "aberrant luminal recanalization." Finally, intrauterine environmental factors, such as trauma or hypoxia during a vascular accident, may cause duplications at any level of the gastrointestinal tract.

Clinical
Presentation depends on the size and location of the duplication.
Cervical duplications: Patients with cervical duplications present with respiratory distress that may be life-threatening and requires rapid diagnosis and treatment.
Thoracic and thoracoabdominal duplications: Respiratory distress caused by airway compression may be noted in younger children; however, in older patients, heartburn or melena has been reported, which is probably caused by the presence of gastric mucosa in one third of patients with thoracic and thoracoabdominal duplications.
Gastric duplications: Patients usually present when younger than 1 year with vomiting, poor feeding, failure to gain weight, and a palpable mass upon physical examination. Hypertrophic pyloric stenosis is often a misdiagnosis in such infants. The mucosal lining of the cysts is often gastric and can lead to melena or hematemesis.
Duodenal duplications: Fifteen percent of these duplications contain ectopic gastric mucosa, which predisposes the patient to ulceration. Peptic ulceration may lead to painless gastrointestinal hemorrhage that can progress to perforation. Duplications may extend into the liver or even transdiaphragmatically. These are generally diagnosed after onset of high intestinal obstruction or hemorrhage that may commonly be accompanied by icterus or pancreatitis.
Small-intestine duplications: Clinical presentation depends on the type, size, location, and mucosal lining of the duplication. Small cystic duplications can be anchor points for intussusception or can result in volvulus, whereas long tubular duplications with proximal communication drain poorly, and retention of intestinal contents can obstruct adjacent intestine. Distal communication is more common and is more difficult to diagnose than proximal communication. Gastric mucosa in a duplication can lead to ulceration and perforation. The diagnosis is often not established before surgery.
Colonic duplications
Cystic colonic duplications are either asymptomatic or present as abdominal masses that may be accompanied by pain. Bleeding may be observed despite the lower prevalence of ectopic gastric mucosa in colon duplications. Newborns may present with volvulus or acute intestinal obstruction.
Tubular colonic duplications are usually asymptomatic, but severe esthetic problems are observed with the duplicated genitalia.
Rectal duplications: Presenting signs of colonic or presacral duplications may include constipation, rectal bleeding, hematochezia, rectal prolapse, hemorrhoids, fistula-in-ano, and perirectal abscess.

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