Congenital malformations of the mitral valve

Congenital isolated cleft mitral valve leaflet and apical muscular ventricular septal defect in a Holstein calf

A 5-week-old Holstein heifer calf presented for emergency treatment of signs referable to gastrointestinal disease and hypovolemic shock. Fluid resuscitation uncovered clinical signs of primary cardiac disease and echocardiography revealed multiple congenital cardiac defects. Malformations included a cleft anterior mitral valve leaflet resembling an isolated cleft mitral valve and an apically-located muscular ventricular septal defect. The echocardiographic and postmortem findings associated with these defects are presented and discussed in this report.

Unguarded mitral orifice associated with hypoplastic left heart syndrome

In the spectrum of mitral valve anomalies, unguarded mitral orifice is an exceedingly rare malformation, with only four cases described in the current literature. All previously reported cases have been associated with discordant atrioventricular connections. We describe the first known case of unguarded mitral valve orifice, in the setting of atrioventricular concordance, in a newborn with hypoplastic left heart syndrome.

An Unreported Congenital Anomaly: Aneurysm of the Lateral Half of the Mitral Valve

This case draws our attention to a new type of mitral valve anomaly, which seems to be congenital. A 42-year-old man with symptomatic primary severe mitral regurgitation was admitted to our hospital. Echocardiography revealed an aneurysm of the half of the valve, on the anterolateral commissure side, with significant excess tissue. The other half of the valve was normal. The two parts seemed to be separated by a continuous fibrous raphe. The anterolateral papillary muscle was hyperplasic and gave the main part of chordae tendinae.

Three-dimensional echocardiography of congenital abnormalities of the left atrioventricular valve

Congenital abnormalities of the left atrioventricular (AV) valve are a significant diagnostic challenge. Traditionally, reliance has been placed on two-dimensional echocardiographic (2DE) imaging to guide recognition of the specific morphological features. Real-time 3DE can provide unique views of the left AV valve with the potential to improve understanding of valve morphology and function to facilitate surgical planning. This review illustrates the features of congenital abnormalities of the left AV valve assessed by 3DE. The similarities and differences in morphology between different lesions are described, both with respect to the valve itself and supporting chordal apparatus. The potential advantages as well as limitations of this technique in clinical practice are outlined.

Echocardiography of congenital mitral valve disorders: echocardiographic-morphological comparisons

I surveyed our echocardiographic database of the years between 1998 and 2012 for congenital abnormalities of the mitral valve in patients over 14 years. A total of 249 patients with mitral valve abnormalities were identified. Abnormalities included clefts in the mitral valve in 58 patients, double orifice of the mitral valve in 19, mitral stenosis with two papillary muscles in 72, and mitral stenosis with one papillary muscle in 51 patients. Supravalvar rings were found in 35 patients with a single papillary muscle, and mitral stenoses with two papillary muscles were found in 22 patients. Mitral prolapse occurred in 44 patients and mitral valvar straddle in five patients. The patients were evaluated by all modalities of ultrasound available over the course of time. Although some lesions were isolated, there were many lesions in which more than one mitral deformity presented in the same patient. The patients are presented showing anatomical correlation with autopsy specimens, some of which came from the patients in this series, and others matched to show correlative anatomy. These lesions remain rare as a group and continue to have high morbidity and mortality.

Unique congenital malformation of the mitral valve associated with anomalous coronary arteries and stroke

A 55-year-old male presented with stroke. Transesophageal echocardiogram and cardiac computed tomography revealed an unrecognized congenital malformation of the anterior mitral leaflet associated with anomalous left coronary circumflex artery, arising from the right coronary artery, diagnosed first by echocardiogram. This case represents a unique unforeseen mitral valve anomaly that might be considered as potential cardiac source of embolism. This finding broadens the spectrum of known mitral valve anomalies.

Nitric oxide synthase-3 promotes embryonic development of atrioventricular valves

Nitric oxide synthase-3 (NOS3) has recently been shown to promote endothelial-to-mesenchymal transition (EndMT) in the developing atrioventricular (AV) canal. The present study was aimed to investigate the role of NOS3 in embryonic development of AV valves. We hypothesized that NOS3 promotes embryonic development of AV valves via EndMT. To test this hypothesis, morphological and functional analysis of AV valves were performed in wild-type (WT) and NOS3^−/− mice at postnatal day 0. Our data show that the overall size and length of mitral and tricuspid valves were decreased in NOS3^−/− compared with WT mice. Echocardiographic assessment showed significant regurgitation of mitral and tricuspid valves during systole in NOS3^−/− mice. These phenotypes were all rescued by cardiac specific NOS3 overexpression. To assess EndMT, immunostaining of Snail1 was performed in the embryonic heart. Both total mesenchymal and Snail1⁺ cells in the AV cushion were decreased in NOS3^−/− compared with WT mice at E10.5 and E12.5, which was completely restored by cardiac specific NOS3 overexpression. In cultured embryonic hearts, NOS3 promoted transforming growth factor (TGFβ), bone morphogenetic protein (BMP2) and Snail1expression through cGMP. Furthermore, mesenchymal cell formation and migration from cultured AV cushion explants were decreased in the NOS3^−/− compared with WT mice. We conclude that NOS3 promotes AV valve formation during embryonic heart development and deficiency in NOS3 results in AV valve insufficiency.

Valve replacement in children: a challenge for a whole life

Valvular pathology in infants and children poses numerous challenges to the paediatric cardiac surgeon. Without question, valvular repair is the goal of intervention because restoration of valvular anatomy and physiology using native tissue allows for growth and a potentially better long-term outcome. When reconstruction fails or is not feasible, valve replacement becomes inevitable. Which valve for which position is controversial. Homograft and bioprosthetic valves achieve superior haemodynamic results initially but at the cost of accelerated degeneration. Small patient size and the risk of thromboembolism limit the usefulness of mechanical valves, and somatic outgrowth is an universal problem with all available prostheses. The goal of this article is to address valve replacement options for all four valve positions within the paediatric population. We review current literature and our practice to support our preferences. To summarize, a multitude of opinions and surgical experiences exist. Today, the valve choices that seem without controversy are bioprosthetic replacement of the tricuspid valve and Ross or Ross-Konno procedures when necessary for the aortic valve. On the other hand, bioprostheses may be implanted when annular pulmonary diameter is adequate; if not or in case of right ventricular outflow tract discontinuity, it is better to use a pulmonary homograft with the Ross procedure. Otherwise, a valved conduit. Mitral valve replacement remains the most problematic; the mechanical prosthesis must be placed in the annular position, avoiding oversizing. Future advances with tissue-engineered heart valves for all positions and new anticoagulants may change the landscape for valve replacement in the paediatric population.