Even as cardiology community is preoccupied with systemic hypertension & CAD , pulmonary arterial hypertension(PAH) is a much neglected , still an important clinical cardiac problem encountered . The irony is self evident , there are half a dozen methods to grade systemic hypertension not even a single stadardised grading available for pulmonary arterial hypertension. The WHO working group defined pulmonary hypertension few decades ago and was not clinically graded .The only grading available is based on the pulmonary vascular biopsy changes (Heath Edwards)
Currently PAH management has gone through revolutionary changes. There is an urgent need for grading this entity .This will facilitate to diagnose , manage and assess the efficacy of the currently available treatment.
Developing countries like ours have a great number of PAH due to rampant rheumatic heart disease. A simple study was done in 100 patients with PAH .Bulk of the study population had RHD .Few had primary pulmonary hypertension .Systolic , diastolic, and mean pressure was assessed by doppler echocardiographic analysis of tricuspid regurgitation (TR) and pulmonary regurgitaion(PR) jets. TR jet provided the systolic PA pressure , PR jet provided mean as well as diastolic PA pressure .TR jet was available in all patients. PR jet was available only in 60 patients .Hence the diastolic andmean PA pressure data has been extrapolated in some and was plotted in a scatter diagram. Five equal quintiles were divided. Patients in first and 2nd quintiles were graded 1 and third and 4th quintile were graded 2 , 5 th was graded 3 respectively. From this cut off points for various grades of PAH were identified .The top 3% of patients with highest PAP were graded as grade 4 and all of them had supra systemic PAH.
The following grading is suggested for PAH*
*This is a preliminary attempt to grade PAH. This could be applicable mainly in rheumatic heart disese and primary pulmonary hypertension .Further refining of methodology is required.PAH grading may be little different in congenital left to right shunts.
Dr.S.Venkatesan MD 
Interesting post and thanks for sharing. Some of the things I thought never before. Thank you for doing something really cool that well written. For many friends about it.