Maverick Story's - December 28, 2024

Dystrophic Bicuspid Aortic Valve & Sudden Cardiac Death

December 28, 2024

0 13 min read

Need for Autopsy in every death –

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Dystrophic Bicuspid Aortic Valve & Sudden Cardiac Death

Sir William Osler was the first to recognise that a dystrophic bicuspid aortic valve is the most common cause of certain congenital anomaly of the heart, where two of the aortic valvular leaflets fuse during development, resulting in a valve that is bicuspid instead of the normal tricuspid configuration. The normal aortic valve has 3 equal-sized leaflets or cusps with 3 lines of coaptation. Bicuspid aortic valves are the most common cardiac valvular anomaly, occurring in 1–2% of the general population. It is twice as common in males as in females.

In adulthood, complications are common, and therefore, the burden of disease from BAV disease is more significant than any other congenital cardiac lesion. Although inheritance is variable, it is a familial disease with an estimated 10% chance of a first degree relative being affected. Additionally, certain gene mutations namely ‘NOTCH1’ have been associated; but despite its importance, our understanding of BAV disease is incomplete and questions remain unanswered about this common condition. Although much of the original focus remained abnormal bi-leaflet valve concentric, the disease is indeed significantly more complex. In many cases, a bicuspid aortic valve (BAV) doesn’t cause any problems, still BAV may become more complex in the later stages of our lives, which may lead to varying degrees of severity of aortic stenosis.

Sudden death in young adults is always a challenge for the autopsy surgeon. Most of the cases of sudden death are related to the cardiovascular system. The other major contributions include infection, epilepsy, intracranial haemorrhage and asthma. Most often, unrecognised structural heart diseases such as hypertrophic cardiomyopathy, dilated cardiomyopathy, arrthymogenic right ventricular dysplasia (ARVD) and premature coronary artery disease (CAD) are the causes for sudden cardiac death in the young. There are some other rare causes of sudden cardiac death which one has to rule out before arriving at the cause of death.

Case Report:

A 48years old male, a Loco Pilot by profession, fell unconscious inside the motor-man’s cabin following a stop at one of the scheduled station in the suburban section of the Indian Railways. The commuters were restless about the train delaying in that station even after the starter signal was on. Upon enquiry, it was found that the Loco Pilot is in an unconscious state. Immediately, he was rushed to the hospital where he was declared brought dead in the mid hours of the day. The family members, who had rushed to the hospital could not disclose any relevant past medical or family history.

On external examination, the body measured 173 cm in length and weighed 78 kgs. The clothes present over the body were intact. Rigor mortis was present throughout the body, and lividity over the back surface of the body was not fixed. On internal examination, heart weighed 500gm. A hard calcified lesion involving the Aortic valves, partially blocking the outflow was noted. Mild calcification of mitral valve was present. Pulmonary and Tricuspid valves were unremarkable. Atherosclerotic changes were present in the Left Anterior Descending artery (LAD). Right lung was adherent to the chest wall, left lung was intact. All the other organs were intact and unremarkable. Organs were eventually sent for Histopathological examination.

Provisional opinion was given as Respiratory & Circulatory failure as a result of aortic stenosis. However, final opinion was reserved, pending HPE report. HPE revealed Bicuspid aortic valve with marked calcification. Left ventricular wall and left papillary muscle hypertrophy was present. Atherosclerosis and significant degree of luminal obstruction were seen in the right coronary artery, left main coronary artery and anterior descending artery. Atherosclerotic lesion was seen in the aorta.

Several statistical analysis has reiterated the fact that – Bicuspid Aortic Valves are the most common cardiac valvular anomaly, occurring in 15 to 20% of the general population. It is twice as common in males as in females. Most cases of bicuspid aortic valve are sporadic, familial clusters have been identified, with incidence as high as 21 to 37% in first-degree relatives of probands.

Increasing evidence suggests an autosomal dominant inheritance pattern with variable penetrance, encompassing the entire spectrum of left heart obstruction. The definitive foetal cardiac structure is generally developed in 08 weeks. The semilunar valves form the division of the truncus arteriosus into two separate channels which form the aortic and pulmonary trunks. In the normal aortic valve, the left and right leaflets of the adult valve are formed from the respective swellings while the posterior leaflet is formed from a swelling in the aortic trunk. The posterior leaflet normally forms from additional conotruncal channel tissue. Abnormalities in this area lead to the development of a bicuspid valve, often through incomplete separation or fusion of valve tissue. Mutations in the signalling and transcriptional regulators ‘NOTCH1 gene map locus 9q’ result in abnormal aortic valve development (BAV) and later to de-repression of calcium deposition.

However, exact pathogenesis of congenital aortic valve malformations is unknown. Proponents of environmental causes believe that abnormal blood flow through the aortic valve during Valvulogenesis results in a failure of cusp separation, however, there is no convincing evidence to support this claim.

A Bicuspid aortic valve is often observed with other left-sided obstructive lesions such as coarctation of the aorta or interrupted aortic arch, suggesting a common developmental mechanism. With degeneration of aging valves, aortic sclerosis and calcification can occur. About 40% of individuals with a bicuspid aortic valve develop complications. The main complications identified in patients with BAV are aortic stenosis, aortic incompetence, aortopathy / dissection, endocarditis, and sudden death. The symptoms of the BAV tend to worsen with increasing measurements stenosis of the severity, valve and orifice. Complications like Critical Aortic Stenosis (CAS) and infective endocarditis may be considered relatively early sources of morbidity and mortality. Patients with bicuspid aortic valves may be completely asymptomatic.

It may be only an incidental finding at autopsy. Bicuspid aortic valve may remain silent and be discovered as an incidental finding on echocardiographic examination of the heart. Hence a thorough examination of heart is required in all cases of sudden death brought for post-mortem examination.

Autopsy and dissection of the heart is vital to diagnosis, particularly when deaths are unexpected in nature. This is vital both for the family to understand the exact cause of demise, and also for any legal or insurance purposes that may follow.