Dynamic left ventricular outflow tract obstruction in critically ill patients.

OBJECTIVE: To review patients managed in an intensive care unit diagnosed with dynamic left ventricular outflow tract obstruction without hypertrophic cardiomyopathy. PATIENTS AND METHODS: Dynamic left ventricular outflow tract obstruction (DLVOTO) is characteristically associated with hypertrophic cardiomyopathy, although it has also been described in patients without this disorder. We reviewed patients managed in two intensive care units over a one year period who were hypotensive and/or resistant to catecholamine infusions.
RESULTS: During the one year period nine critically ill patients were found on echocardiography to have DLVOTO. None of the patients had a prior history of hypertrophic cardiomyopathy (HOCM) or echocardiographic evidence of asymmetrical septal hypertrophy and in three patients HOCM was specifically excluded by prior or convalescent echocardiography or by post mortem analysis. We found the risk factors for DLVOTO included left ventricular hypertrophy, hypovolaemia and use of positive inotropic agents. All patients responded to an increase in intravascular volume, reduction in infused inotropic agents with one requiring metaraminol to maintain blood pressure.
CONCLUSIONS: Dynamic left ventricular outflow tract obstruction without hypertrophic cardiomyopathy is not an uncommon cause of hypotension resistant to catecholamines in critically ill patients. The diagnosis is important because management which includes fluid loading, vasopressors and reducing catecholamine infusions, differs from the management of other causes of shock.