Familial primary pulmonary hypertension is a rare, progressive, autosomal dominant disease characterized by monoclonal plexiform lesions of proliferating endothelial cells in pulmonary arterioles, leading to elevated pulmonary-artery pressures, right-ventricular failure, and death. The disease can occur from infancy throughout life; it has a mean age at onset of 36 years, and the ratio of affected females to affected males is 2:1. The average life expectancy after diagnosis is two to three years with death usually due to progressive right heart failure. The pathogenesis of primary pulmonary hypertension is unknown. Although most cases appear to be sporadic, approximately 6% of cases are inherited in an autosomal dominant manner with high, but incomplete penetrance.
By linkage analysis, the localization of the gene familial primary pulmonary hypertension gene could be identified to a locus on chromosome 2q33. Mutations in the bone morphogenetic protein type II receptor (BMPR2) gene causes familial primary pulmonary hypertension. Germline mutations of BMPR2 are also found in >26% of sporadic cases of primary pulmonary hypertension. Primary pulmonary hypertension may also be found in association with hereditary hemorrhagic telangiectasia type 1&2, which is caused by mutation in the ENG gene and ACVRL1 gene, respectively.
Endrys et al. (1997) compared the visualisation of bronchopulmonary collaterals and bronchopulmonary collateral blood flow in patients with chronic thromboembolic pulmonary hypertension and primary pulmonary hypertension. Nine patients with chronic thromboembolic pulmonary hypertension and 17 with primary pulmonary hypertension were analzyed. Bronchopulmonary collaterals were visualised by selective bronchial arteriography or thoracic aortography. Bronchopulmonary collateral blood flow was estimated by injecting indocyanine green into the ascending aorta and sampling below the mitral valve from the left ventricle. None of the primary pulmonary hypertension group studied by aortography had bronchopulmonary collaterals. In addition, Endrys et al. (1997) observed no recordable collateral blood flow in 11 of 15 patients with primary pulmonary hypertension. In patients with primary pulmonary hypertension there was symmetrical dilatation of proximal and hilar pulmonary arteries with relatively rapid taper and marked peripheral arterial pruning.
Manzar et al. (2004) conducted a retrospective study for all neonates with pulmonary hypertension born in the period between July 1998 and June 2003. Out of 37 neonates with pulmonary hypertension, 22 neonates survived and 15 neonates expired, thus, a mortality of approximately 40%. Primary pulmonary hypertension in neonates was noted to be associated with poor outcome as compared to secondary pulmonary hypertension.
Bener et al. (2004) undertook a cross-sectional study to determine the prevalence of hypertension and the cardiovascular risk factors among the Qatari population between 25 and 65-years of age. A multistage stratified cluster sampling design was used to select 1500 subjects (57.9% females) from 10 primary health care centers (8 urban, 2 semi urban) in Qatar. The subjects were interviewed and clinically assessed (response rate: 80.5%). The overall prevalence of hypertension was found to be 32.1% (32.6% males; 31.7% females). Women were found to have a significantly higher CVD risk factor of obesity as well as physical inactivity when compared to males, while smoking was significantly more common in males. When compared to normotensive subjects, the hypertensive subjects were shown to have significantly increased rates of obesity, and medical conditions such as diabetes mellitus, heart disease, and hormonal disorders. A stepwise logistic regression analysis revealed that the associated risk factors for hypertension in the Qatari population were diabetes, hormonal disorders, ingestion of animal fat, heart disease risk, and obesity.
A similar cross-sectional study was carried out by Al-Mulla and Bener (2006) on a sample of 1,789 Qatari hypertensive patients (74.4% females). The study revealed a higher prevalence of hypertension among males over 60-years of age than females. Hypertension was also found to be more common in families having more than three children, male patients working in the government sector, and housewives. Significantly more female hypertensives were obese as compared to their male counterparts, while there were significantly more male smokers. Serum creatine was higher in males, while total and LDL cholesterol levels were higher in females. [Al-Mulla A, Bener A. The pattern of hypertension in a rapidly developing Arabian Qatari population: hospital based study. J Bahrain Med Soc. 2006; 18(1):13-8.]
Al Talabani et al. (1998) studied the pattern of major congenital malformations in 24,233 consecutive live and stillbirth at Corniche hospital, which is the only maternity hospital in Abu Dhabi, between January 1992 and January 1995. A total of 401 babies (16.6/1,000), including 289 Arabs, were seen with major malformation. Multifactorial disorders accounted for 26% of the cases. In their study, Al Talabani et al. (1998) observed one case of primary pulmonary hypertension in a family from the United Arab Emirates. Recurrence was not reported in the family. Al Talabani et al. (1998) concluded that their study was very close to representing the true incidence of congenital abnormalities in the whole United Arab Emirates, as they investigated over 98% of deliveries in Abu Dhabi, the capital of United Arab Emirates.