title: Provocation of latent left ventricular outflow tract gradients with amyl nitrite and exercise in hypertrophic cardiomyopathy.
abstract: Amyl nitrite may be used to provoke latent gradients in patients with hypertrophic cardiomyopathy (HC) without significant resting outflow tract gradients, but afterload reduction may not be comparable to a more physiologic stressor such as symptom-limited exercise testing. This study compared the ability of amyl nitrite and exercise testing to provoke outflow tract gradients in 57 patients (40 men and 17 women, mean age +/- SD 49 +/- 16 years) with HC (septal thickness 19 +/- 5 mm, average resting gradient 13 +/- 10 mm Hg) who underwent echocardiography at rest, after amyl nitrite inhalation, and after maximal exercise. No significant gradient (< 50 mm Hg) was induced after either provocation in 26 patients (46%); in 15 patients (26%), inducibility was achieved after both stressors, in 6 (11%) after exercise only, and in 10 (18%) after amyl only. Patients with amyl-induced gradients differed from those in whom gradients were noninducible on the basis of smaller outflow tract dimensions (p < 0.001), larger resting gradients (p < 0.001), and a greater prevalence of "septal bulge" morphology (p = 0.02). Those with exercise-induced gradients were able to attain a greater workload (p = 0.07), have larger resting gradients (p = 0.02), and also tended to have a septal bulge morphology (p < or = 0.01). Although outflow tract obstruction increased to similar levels after amyl nitrite (49 +/- 39 mm Hg) and symptom-limited exercise (47 +/- 39 mm Hg), gradients induced by exercise and amyl correlated poorly (r = 0.54).(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Department of Cardiology, Cleveland Clinic Foundation, Ohio 44195, USA.
authors.forename: T H
authors.initials: TH
authors.lastname: Marwick
authors.forename: S
authors.initials: S
authors.lastname: Nakatani
authors.forename: B
authors.initials: B
authors.lastname: Haluska
authors.forename: J D
authors.initials: JD
authors.lastname: Thomas
authors.forename: H M
authors.initials: HM
authors.lastname: Lever
mesh_terms: D000280:Administration, Inhalation; D000328:Adult; D000680:Amyl Nitrite / Q000008:administration & dosage / Q000494:pharmacology*; D001794:Blood Pressure / Q000502:physiology; D002312:Cardiomyopathy, Hypertrophic / Q000000981:diagnostic imaging / Q000503:physiopathology*; D004452:Echocardiography; D005260:Female; D005500:Follow-Up Studies; D006339:Heart Rate / Q000502:physiology; D006346:Heart Septum / Q000000981:diagnostic imaging; D006801:Humans; D008297:Male; D008875:Middle Aged; D005082:Physical Exertion / Q000502:physiology*; D012146:Rest / Q000502:physiology; D013318:Stroke Volume / Q000187:drug effects / Q000502:physiology*; D016277:Ventricular Function, Left / Q000187:drug effects / Q000502:physiology*; D014694:Ventricular Outflow Obstruction / Q000139:chemically induced / Q000000981:diagnostic imaging / Q000209:etiology*; D016526:Workload
chemical_list: D000680:Amyl Nitrite