Pulmonary Arterial Hypertension
Pulmonary arterial hypertension (PAH) is an occlusive disease of the pulmonary arteries leading to serious hemodynamic abnormality, right heart failure, and premature death. PAH can occur as a primary disease or as a secondary condition to a large number of respiratory and cardiac diseases. PAH is both difficult to diagnose and easy to misdiagnose as symptoms are frequently masked by other medical conditions affecting the heart and lungs. Better diagnosis and classification of PAH patients is an urgent priority among pulmonologists, because drugs now exist that treat some of the underlying causes of PAH. The proper drug can only be selected when the disorder is accurately diagnosed and characterized. This has proved difficult, as non-surgical methods for obtaining endoarterial specimens necessary for biopsy analysis have heretofore not been available. This limitation has represented a major drawback in the medical management of PAH patients.
A recent study of >10,000 US Veterans revealed a surprisingly high prevalence of all types of PH (3.2%) based on screening echocardiograms, and a relatively low rate of recognition (17.3%) by providers.1 In this cohort, nearly half of patients were deceased at an average follow-up of less than 3 years after the index echo, consistent with historical NIH registry data from the 1980s with a median survival of 2.8 years following diagnosis.2 The prevalence of secondary PAH is conservatively estimated to be 2 to 4 million due to its close associations with common cardiovascular diseases such as congestive heart failure (CHF), and lung diseases including chronic obstructive pulmonary disease (COPD) and pulmonary embolism.
Fifty percent of PAH patients die within 5 years, despite treatment. Current PAH therapies sadly lack the ability to save these lives. While all pulmonary hypertensive patients share the same general diagnosis, they respond differently to treatment. Some patients respond temporarily to some therapies while other patients do not. Drug therapies that temporarily help some patients lose effect sooner or later. When drugs do work, serious side effects and complications plague most patients. Prescriptions for each PAH patient can run into the hundreds of thousands of dollars per year, despite their eventual ineffectiveness. The diagnosis and treatment of PAH will be greatly enhanced by the use of the endoarterial biopsy catheter.
VBS Interventional intends to improve survival and medical outcomes in PAH by giving physicians detailed information about patient pulmonary arteries – the site where the disease is actually occurring. Specifically, that means that our endoarterial biopsy catheter will obtain endothelial and smooth muscle cell biopsies from the pulmonary arteries of PAH patients. The physician will receive a complete pathological profile from these biopsies and have a better idea of what medicines will or will not work for an individual patient at a particular time. Pulmonary endothelial and smooth muscle cells are thought to be the primary sites of disease progression in PAH, so these are the cells that the endoarterial biopsy catheter will biopsy and analyze for the physician.
Like many vascular diseases (e.g. cancer), PAH involves a complex cellular process that evades treatment. PAH impairs normal signaling and growth in both pulmonary endothelial and pulmonary smooth muscle cells, yet the cellular abnormalities seen in PAH seem to shift over time in unpredictable patterns that has thus far escaped concise definition. The inability to test a patient’s cells outside the body has prevented physicians from arresting PAH’s inexorable progression. The common practice of biopsy-driven decision making in cancer treatment is missing in PAH care, and it’s something that PAH physicians are beginning to recognize as long overdue in today’s era of advanced molecular analysis. VBS Interventional will fill the need for biopsy-driven medical management for pulmonary vascular disease patients.
The endoarterial biopsy catheter promises to profoundly improve pulmonary hypertension treatment for the better, and we have good reason to believe it will be well-received. Two editorials by leading experts in pulmonary hypertension – the late Dr. Robyn Barst of New York-Presbyterian Hospital/Columbia University Medical Center3 and Dr. Evangelos Michelakis, Canada’s National Chair in Pulmonary Hypertension4 – have both called in peer-reviewed medical journals for the use of the endoarterial biopsy catheter to improve PAH patient care.
Beyond improving diagnosis, we are utilizing the endoarterial biopsy catheter’s drug discovery ability to find new ways of arresting and even reversing the PAH proliferative process by identifying the molecular pathways underlying PAH disease formation and progression. Our current research in animal models of PAH have identified entirely unanticipated molecules and proteins involved in this deadly disease. Medicines that inhibit or reverse these molecular pathways will become the PAH drugs of the future, pointing the way to pharmaceuticals that truly cure.
1. Maron, B.A., et al. Clinical Profile and Underdiagnosis of Pulmonary Hypertension in US Veteran Patients. Circ Heart Fail 6, 906-912 (2013).
2. O’Callaghan, D.S. & Humbert, M. A critical analysis of survival in pulmonary arterial hypertension. Eur Respir Rev 21, 218-222 (2012).
3. Barst, RJ. Pulmonary vascular disease: Our need to understand. Chest. 1998; 114:8-9.
4. Michelakis, ED. Spatio-temporal diversity of apoptosis within the vascular wall in pulmonary arterial hypertension: Heterogeneous BMP signaling may have therapeutic implications. Circ. Res. 2006; 98:172-175.
WARNING: Investigational Device. Limited by Federal law to investigational use. This device should be used only by physicians with a thorough understanding of percutaneous interventional procedures and training in the use of the endoarterial biopsy catheter.
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