Left ventricular decompression through a patent foramen ovale in a patient with hypertrophic cardiomyopathy: a case report
© Ando' et al; licensee BioMed Central Ltd. 2004
Received: 05 January 2004
Accepted: 16 January 2004
Published: 16 January 2004
The foramen ovale is considered an unidirectional flap-like valvular structure. Yet, it may increase in size and allow a continuous left-to-right shunt in order to reduce left ventricular filling pressures.
We report the case of a 63-year-old woman with hypertrophic cardiomyopathy, referred for percutaneous closure of a coexisting secundum atrial septal defect. Before catheterization, however, transesophageal echocardiography revealed a continuous left-to-right shunt within the atrial septum, thus suggesting the diagnosis of patent foramen ovale with stable left-to-right shunt. At catheterization, performed under general anesthesia and transesophageal echocardiographic monitoring, left ventricular early- and end-diastolic pressures were 2 and 12 mmHg and pulmonary-to-systemic flow ratio was 1.4. Provocative maneuvers were not able to reverse the shunt. In order to assess the effect of the increased left ventricular preload due to the abolition of the shunt, an Amplatzer sizing balloon was inflated for 5 minutes across the patent foramen ovale. Diastolic pressures rose up to 5 and 18 mmHg, respectively. Such a worsening of left ventricular function suggested us not to perform the closure procedure.
Transcatheter closure of any interatrial communication with stable left-to-right shunt induces an abrupt overload of the left ventricle that may cause acute heart failure in patients with coexisting left ventricular dysfunction. The hemodynamic evaluation of left ventricular function during transient abolition of the shunt is an useful tool in order to establish the most correct therapeutic strategy. The closure procedure should not be performed if a worsening of left ventricular function occurs.
Transcatheter percutaneous closure of ASD is recommended as a preferable alternative to surgical repair, since excellent results in terms of efficacy and complications  are associated with shorter hospitalization and lower morbidity . It should be kept in mind, yet, that the sudden interruption of the left-to-right shunt at the time of the definitive percutaneous closure causes an abrupt LV overload and a consequent increase in myocardial oxygen consumption. Such hemodynamic changes may be harmful in patients with LV dysfunction  and in elderly patients  with reduced LV compliance and can lead to acute heart failure [3–6]. Thus, whenever an ASD coexists with LV dysfunction, a rapid evaluation of the hemodynamic effects of the abolition of the left-to-right shunt is useful for clinical decision making.
We report the case of an apparent secundum ASD in whom both TEE and a real-time hemodynamic evaluation of LV function during transient abolition of the shunt helped us to advance the most accurate diagnosis and to establish the most correct therapeutic strategy.
The wide application of contrast TEE has revealed that paradoxical embolism through a PFO is likely to represent an under-recognized cause of stroke , but fewer reports have highlighted the possibility of a stable left-to-right shunt through a PFO , since the foramen ovale is generally considered an unidirectional flap-like valvular structure, that is functionally closed when left atrial pressure is higher than right. Nevertheless, it has been speculated that the foramen ovale may increase in size and allow a left-to-right overflow secondary to pressure-induced left atrial enlargement ; such a shunt may be easily misdiagnosed as secundum ASD at transthoracic echocardiography. Moreover, in the case of LV restrictive physiology, like in hypertrophic cardiomyopathy, a continuous left-to-right shunt through a PFO may act as an unloading mechanism for the left atrial chamber finalized at reducing LV filling pressures. Therefore it may be useful, in such cases and prior to any interventional procedure, to perform, under the controlled conditions due to general anesthesia, a rapid hemodynamic evaluation of the effect of the transient abolition of the shunt on LV function. This evaluation can easily be obtained with the inflation of the sizing balloon across the interatrial communication. The percutaneous closure procedure should not be performed if a worsening of LV function occurs.
The abrupt LV overload due to transcatheter closure of ASD may induce acute heart failure in patients with associated LV dysfunction. The assessment of LV filling pressures during transient abolition of the shunt permits a real time evaluation of LV function in the new hemodynamic conditions that is useful to clinicians in order to manage the patient with the most appropriate therapeutic strategy. Such evaluation should be performed, prior to definitive closure of any abnormal interatrial communication with a stable left-to-right shunt, in all patients with coexisting LV dysfunction in whom the consequent increase in LV preload could not be hemodynamically tolerated and lead to acute heart failure.
List of abbreviations
Atrial Septal Defect
Patent Foramen Ovale
GA has received a grant by the Italian Society of Cardiology for a Fellowship in Interventional Cardiology at the Department of Cardiac Surgery of the Tor Vergata University of Rome.
Written consent was obtained from the patient for the publication of this case report.
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