Novel Use of Intra-arterial Doppler in the Assessment of Pulmonary Artery Flow Velocities—Observations Before and After Therapy for Pulmonary Arterial Hypertension

Abstract

Background: Intra-arterial Doppler is a novel technique which enables accurate assessment of blood flow haemodynamics. We evaluated the feasibility of using intra-arterial Doppler for insights into the pulmonary artery flow velocity profile in patients with pulmonary arterial hypertension (PAH), and determined the changes in the flow velocity profile following pulmonary vasodilator therapy. Methods: Intra-arterial Doppler was performed in the pulmonary arteries of seven subjects with PAH before and after six months of Bosentan therapy. The following Doppler derived parameters weremeasured: acceleration time (AcT), systolic ejection time (ET), ratio of acceleration time to systolic ejection time (AcT/ET), systolic velocity time integral (sVTI), diastolic velocity time integral (dVTI) and total velocity time integral (tVTI). Relationships between Doppler parameters and clinical response to Bosentan therapy were analysed. Results: At baseline, all PAH patients displayed a standardised pharmacological treatment and computer assisted, intensified follow-up and treatment titration). Methods: VIPER-BP is a multicentre, open-label, randomisedcontrolled trial inGPclinics throughoutAustralia comparing usual GP management with an intensive BP management strategy using three forms of valsartanbased therapy. The primary endpoint is individualised BP control at six months. Results: During recruitment 2334 patients initially screened. Of these, 2131 (91%) commenced a 28 day valsartan 80mg “run-in” phase. Subsequently, 310 patients achieved their individualBP target (15%)whilst 81patients (5.2%) were rescue randomised. Overall, 1555 patients were randomised to usual care (n= 519) or the VIPER-BP Intervention (n= 1036): comprising 948men (62%) and 607 women (aged 59± 12 vs. 60± 12 years, respectively) and 1004 patients (65%) previously treated for hypertension. Individual BP targets (systolic/diastolic BP) were as follows; 125/75mmHg (18%withproteinuria), 130/80mmHg (55% with diabetes or CVD) and 140/90mmHg (27%). Mean BP at randomisation was 149± 17/88± 11mmHg with similar BP profiles for men and women, respectively (149± 16/88± 11 versus 149± 17/87± 10mmHg). Conclusion:With study completion in August 2011, the VIPER-BP Study will provide invaluable insights into the most effective means to optimise BP levels (on an individualised basis) in the primary care setting.