Ventricular outflow obstruction

Hypertrophic cardiomyopathy (IHSS) Serious adverse effects were seen in 120 patients with IHSS (especially with pulmonary artery wedge pressure more than 20 mm Hg and left ventricular outflow obstruction) who received oral verapamil at doses up to 720 mg/day. Sinus bradycardia occurred in 11%, second-degree AV block in 4% and sinus arrest in 2%. 

Patients with the following underlying conditions can be particularly sensitive to the actions of vasodilators, including sildenafil, tadalafil, and vardenafil Those with left ventricular outflow obstruction (eg, aortic stenosis, idiopathic hypertrophic subaortic stenosis) and those with severely impaired autonomic control of blood pressure. 

Reduction of the left ventricular outflow obstruction and antiarrhythmic activity underlying the beneficial effect of verapamil. 

Approximately 25% of all patients with hypertrophic cardiomyopathy (HCM) have latent left ventricular outflow obstruction with an intraventricular gradient (I). Pathophysiologic features are asymmetric hypertrophy of the septum and a systolic anterior movement of the anterior leaflet. Medical treatment includes betablockers, and calcium antagonists of the verapamil type. Approximately 5— 10% of the patients with outflow obstruction are refractory to such negative inotropic therapy (2). Positive inotropic drugs such as digitalis or sympathomimetics are strictly contraindicated. In the presence of atrial fibrillation, anticoagulation therapy should be started. Since endocarditis is more common in patients with HCM because of turbulence in the left ventricle, prophylactic antibiotics should be administered for periods of potential bacteraemia. 

Hatle L (1981) Noninvasive assessment and differentiation of left ventricular outflow obstruction with doppler ultrasound. Circulation 66 381... 

Maron MS, Olivotto I, Betocchi S, etal. Effect of left ventricular outflow tract obstruction on clinical outcome in hypertrophic cardiomyopathy. N Engl J Med 2003 348 295-303. 

Ruzyllo W, Chojnowska L, Demkow M, et al. Left ventricular outflow tract gradient decrease with non-surgical myocardial reduction improves exercise capacity in patients with hypertrophic obstructive cardiomyopathy, Eur Heart J 2000 21 770-777. 

Aortic stenosisAeft ventricular outflow tract obstruction an ACE inhibitor may cause severe, sudden hypotension and, depending on severity, is relatively or absolutely contraindicated. 

Obstruction of ventricular outflow where sympathetic activity occurs in the presence of anatomical abnormalities, e.g. Fallot s tetralogy (cyanotic attacks) ... 

Cardiac glycosides are contraindicated in conditions in which there is obstruction to ventricular outflow, for example hypertrophic obstructive cardiomyopathy, constrictive pericarditis, and cardiac tamponade. Acute myocarditis may also increase the risk of toxicity. 

Acute subaortic left ventricular outflow tract obstruction has been described during dobutamine infusion in a patient who had no evidence of this at rest but developed severe obstruction when his pulse rate exceeded 105/minute... 

Roldan FJ, Vargas-Barron J, Espinola-Zavaleta N, Keirns C, Romero-Cardenas A. Severe dynamic obstruction of the left ventricular outflow tract induced by dobutamine. Echocardiography 2000 17(1) 37 0. 

Dyspnea, chest pain or syncope, usually features ventricular hypertrophy with impingement on LV volume and often LV outflow obstruction. Most cases hereditary, but some are new mutations. Defective genes for/3-MHC, either MLC, TnT, Tnl, a-tropomyosin, myosin binding protein C. 

Patients with left atrial hypertension may have an elevated pulmonary vascular resistance because the cardiac index is low, the pulmonary vasculature is constricted, or there is fixed pulmonary vascular obstructive disease with a reduction in recruitable lung vessels. Peroperative assessment may be aimed at increasing cardiac output with drugs such as dobutamine or by combining vasodilation and an increase in cardiac output with drugs such as nitroprusside or prostacyclin. The use of catecholamines or systemic vasodilators is not without risk, especially in patients with left ventricular outflow tract obstruction, as in two of our patients, or in patients with... 

We have reported the effect of inhaled nitric oxide in 10 patients (median age, 3.3 years range, 0.4-11.1 years) with symptomatic congenital mitral stenosis.These studies were performed during interventional cardiac catheterization or after surgery requiring the use of cardiopulmonary bypass. Six patients had additional left ventricular outflow tract obstruction (median, 25 mm Hg range, 15-50 mm Hg). Effective relief of the mitral gradient was present after intervention. 

Cherian J, Kothari S, Angelis D, Atef A, Downey B, Kirkpatrick Jr. J. Atypical takotsubo cardiomyopathy dobutamine-precipitated apical ballooning with left ventricular outflow tract obstruction. Tex Heart Inst J 2008 35(1) 73-5. 

Kanter, K.R. et al.. One hundred pulmonary valve replacements in children after relief of right ventricular outflow tract obstruction. Ann Thorac Surg, 2002. 73(6) p. 1801-6 discussion 1806-7. 

Balys R, Manoukian J, Zalai C. Left ventricular hypertrophy with outflow tract obstruction-a complication of dex- 48. amethasone treatment for subglottic stenosis. Int J Pediatr Otorhinolaryngol 2005 69(2) 271-3. 

Contraindications are hypertrophic obstructive cardiomyopathy (increase in inotropism can increase outflow tract obstruction), AF in WPW syndrome (can cause precipitation of the arrhythmia to ventricular fibrillation (VF) by preferential conduction over the accessory pathway), significant AV-block or sick sinus syndrome, hypokalemia (causes increased digoxin sensitivity and supraventricular/ventricular arrhythmia), thyreotoxicosis, postinfarction status (increased mortality). Caution should be exerted in renal failure, and coadministration of other drugs depressing sinus node or AV-nodal function. 

Hypertrophic cardiomyopathy a primary myocardial disorder of sacromeric proteins with an autosomal dominant pattern of inheritance is characterized by asymmetric hypertrophy of the septum with or without dynamic obstruction of the outflow tract (1,2), The prevalence in the general population is estimated as 1 500 and it is the most common monogenic cardiac disorder, Annual mortality in an unselected population is reported to be about I % to 2%, and sudden death is the most common cause, Sudden death is assumed to be due to idiopathic ventricular arrhythmias, but hemodynamic factors and myocardial ischemia may be involved as well. 

Left ventricular pressure measurements are monitored continuously by use of a 5F end-hole pig-tail catheter in the left ventricular apex and a 6F femoral sheath in order to be able to assess the gradient, If the outflow gradient is absent or small under the basal conditions, the magnitude of provocable obstruction is most appropriately assessed with maneuvers (Valsalva, ventricular pacing, extrasystoles, physiological exercise, amyl nitrate), The inability to elicit any provocable gradient is a contraindication to the procedure,... 

---