Percutaneous Balloon Dilation of Discrete Subaortic Stenosis: A Futile Exercise

Discrete subaortic stenosis (DSS) is a progressive obstruction of left ventricular outflow tract (LVOT) resulting in the development of aortic regurgitation in its natural course. Hence, early intervention is recommended. Percutaneous balloon dilation of DSS has been reported and can substantially reduce LVOT pressure gradient. The response to balloon dilation of DSS is transient and may complicate with chordal or papillary muscle rupture. Hence, balloon dilation of DSS should be discouraged.

Diagnosis and surgical management of subaortic stenosis and mitral valve systolic anterior motion

The case is reported of a patient with a previously undiagnosed cause of severe congestive heart failure (CHF) caused by the presence of a discrete subaortic stenosis (SAS) from a subvalvular membrane (SVM). The clinical decision making was complicated by the concurrent presence of systolic anterior motion (SAM) of the mitral valve leaflet. Due to the limitations and eventual failure of physiologically opposing medical management strategies, the patient eventually required an open-heart surgical approach and underwent intraoperative SVM resection. A persistent intraoperative left ventricular outflow tract (LVOT) gradient of 50 mmHg due to SAM prompted mitral valve replacement, which resulted in a complete resolution of the LVOT gradient and symptoms. In this extremely rare scenario of SAS and SAM, when SVM resection is thought to be inadequate to relieve LVOT obstruction due to the concurrent presence of SAM, mitral valve replacement represents a reasonable therapeutic approach.

Discrete subaortic stenosis in an adult Nigerian: a case report

BACKGROUND

Cases of discrete subaortic stenosis are rare in adults. To our knowledge, no case has been reported in Nigerian literature. Cases are thus likely to be missed or wrongly managed.

OBJECTIVE

To present a case of discrete membranous subaortic stenosis in an adult Nigerian with a view to creating awareness of the existence of this entity in our milieu.

METHODS

The patient a 46-year-old Nigerian presented with symptoms of angina pectoris and near syncope. Transthoracic 2-Dimensional / M-mode echocardiography demonstrated thickened and calcific aortic valves and laboratory investigations showed that he also had artherogenic dyslipidaemia. He was initially managed as a case of severe valvular aortic stenosis of rheumatic origin with associated dyslipidaemia and was referred for further evaluation and management abroad.

RESULTS

On further assessment at the referral centre, the diagnosis was reviewed to subaortic stenosis with severe left ventricular outflow tract obstruction (LVOTO) arising from a fibro muscular subaortic membrane after a repeat 2-D/M-mode and Doppler echocardiography. Coronary angiography showed normal coronaries. He had excision of the membrane with marked reduction in gradient across the left ventricular outflow tract. He has remained symptom free and stable thereafter.

CONCLUSION

Discrete membranous subaortic stenosis though rare in adults should be suspected in patients with clinical features of valvular aortic stenosis. Doppler echocardiography is thus mandatory in the evaluation of these patients.

[Obstruction of the left ventricular outflow tract caused by bicuspid aortic valve and discrete subaortic membrane]

Bicuspid aortic valve is the most common congenital cardiac anomaly and it may often coexist with other congenital cardiac anomalies. Its coexistence with discrete subaortic membrane, causing obstruction of the left ventricular outflow tract is very rare. A 21-year-old male patient presented with complaints of exertional dyspnea and dizziness. On transthoracic echocardiography, the parasternal short-axis view showed a bicuspid aortic valve, and parasternal long-axis color Doppler view showed a mosaic pattern in the subaortic region. A more careful examination of the parasternal long-axis views revealed a discrete subaortic membrane. Continuous-wave Doppler flow velocity obtained from the aortic valve was normal; however, a peak gradient of 30 mmHg was observed with the Valsalva maneuver. The fact that there are very few reports on this rare coexistence may be due to failure to recognize discrete subaortic membrane during echocardiographic examination.

Congenital Heart Diseases in the Boxer Dog: A Retrospective Study of 105 Cases (1998–2005)

Subaortic stenosis (SAS) is one of the most common congenital heart diseases (CHD) in dogs with Boxers being predominantly affected. However, the increasing availability of modern diagnostic imaging systems now allows a better assessment of cardiac morphology and function, thereby facilitating early detection of CHD in awake animals. In this context, the case records of Boxer dogs diagnosed with CHD using echocardiography combined with Doppler mode, were retrospectively reviewed (1998-2005). One hundred and five Boxers exhibiting either a single CHD (53/105, 50.5%) or association of several CHD (52/105, 49.5%) were included. The most common CHD was atrial septal defect (ASD) observed in 56.2% of these animals (59/105), followed by mitral dysplasia (58/105, 55.2%), and SAS (49/105, 46.7%). SAS was associated with one or two CHD in 29.5% of cases (31/105). Most of the dogs with a low intensity left heart base systolic murmur had an isolated ASD whereas most of the dogs with a similar but high intensity murmur had SAS, either isolated or associated with a concurrent CHD. The incidence of ASD and mitral dysplasia in Boxer dogs is higher than previously assumed, and ASD is a common cause of left heart base systolic murmur in this breed of dog. This confirms that the detection of such a murmur should not be used as the unique criterion for diagnostic confirmation of SAS.

[Discrete subaortic stenosis with pressure recovery: a case report]

A 54-year-old woman with subvalvular aortic stenosis was admitted to our hospital. The pressure gradient across the left ventricular outflow tract was estimated as 88 mmHg (peak) and 45 mmHg (mean) by Doppler echocardiography, but only 14 mmHg (peak to peak) and 31 mmHg (mean) by cardiac catheterization. We considered this discrepancy attributable to the presence of moderate aortic regurgitation and the pressure recovery phenomenon. Pressure recovery has clinical relevance particularly in a patient with tunnel-like stenosis, with gradual lumen re-expansion beyond the limiting orifice. Therefore, if Doppler echocardiography shows significant left ventricular outflow tract gradient, precise evaluation of the stenosis geometry is required to investigate the effect of pressure recovery.

Proximal isovelocity surface area (PISA) in the evaluation of fixed membranous subaortic stenosis

The evaluation of the severity of subaortic stenosis is usually expressed by the magnitude of the subvalvular gradient. Calculation of the membrane orifice area noninvasively is difficult by the standard means. We present a patient in whom the area was calculated using the proximal isovelocity surface area (PISA) method. This method should have clinical applicability because it is not flow dependent and can be used in patients with normal, reduced, or increased stroke volume.

Considerations in biventricular repair after the Norwood procedure

OBJECTIVE

The Norwood procedure can be applicable as a first stage palliation in children who can eventually undergo a biventricular repair. Although usual management of these patients is a primary neonatal repair, in selected patients staged approach with a Norwood procedure in the neonatal period followed by a Rastelli procedure in the infancy for conversion to two-ventricle physiology has been used alternatively.

METHODS

We report our experiences on two infants who underwent a previous palliation with the Norwood procedure for lesions other than hypoplastic left heart syndrome and converted to two-ventricle physiology by the use of a Rastelli-type procedure. This report examines considerations in biventricular repair after the Norwood procedure especially need for ventricular septal defect enlargement and approach to placement of the right ventricle to pulmonary artery conduit.

RESULTS

Both of the infants who underwent staged approach with an initial Norwood procedure for lesions other than hypoplastic left heart syndrome survived the operations and were clinically well at mid-term follow-up.

CONCLUSION

In selected patients, the staged approach is an alternative in management of malformations other than hypoplastic left heart syndrome which share the important physiologic features of aortic outlet obstruction and ductal dependency of systemic circulation. We recommend routine enlargement of ventricular septal defect and proper positioning of the conduit at the time of subsequent biventricular repair.