A patient may be born with a congenital stenosis, or acquire the stenosis from secondary conditions such as rheumatic heart disease or idiopathic calcification of the valves. Persons born with an abnormal bicuspid valve are particularly susceptible to calcification later in life.

 

The pathogenesis of aortic stenosis is most commonly progressive calcification and degeneration of a trileaflet or congenitally bicuspid valve. Although once thought to be a degenerative process, it is now recognized that calcific aortic stenosis is in fact an active disease process that shares similarities to atherosclerosis where there is inflammation, lipid accumulation, and calcification of the leaflets.

The mechanisms by which some valves degenerate and become stenotic while others remain relatively normal are unknown but are probably related to genetic polymorphisms. Those with end-stage renal disease, Paget disease, or severe familial hypercholesterolemia may present with calcific aortic stenosis at a younger age and are susceptible to more rapid progression of stenosis severity.

Rheumatic valve disease is a rare cause of aortic stenosis in industrialized nations. However, for indigenous populations within these countries as well as in developing countries, there remains a significant prevalence of rheumatic valve disease. In contrast to calcific aortic valve stenosis, the rheumatic valve shows adhesion, leaflet retraction, and commissural fusion. Along or just a few millimeters away from the free margins of the valve leaflets, small sessile nodules develop that also contribute to leaflet malcoaptation. Therefore, the rheumatic aortic valve invariably will leak. Rheumatic aortic valve disease is almost never present in isolation, and there is invariably concomitant mitral valve disease. A patient with aortic stenosis and a perfectly normal mitral valve should be considered as having another cause for their disease. Other rare causes of aortic stenosis include those associated with connective tissues diseases such as systemic lupus erythematosus and ochronosis.

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Aortic stenosis is a progressive disease, with typical symptoms and clinical findings to match its course. A good mnemonic to remember the march of symptoms related to undiagnosed aortic stenosis is ASC, or Aortic Stenosis Complications. One of the early symptoms is Angina, which is usually stable and exertion-related. A more serious and later condition is Syncope, again associated with exercise. Finally, the hypertrophied left ventricle can no longer meet demands, and Congestive heart failure may ensue. On examination, the phase during systole at which the murmur peaks can help to determine the severity of the disease. An early-peaking murmur is usually associated with a less stenotic valve, while a late-peaking murmur has a more severe degree of stenosis. This is because a more stenotic valve takes longer for the ventricle to generate the terrific pressures needed to force the blood past the lesion.1

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Complications of Injecting Drug Use

  • Local problems—Abscess (Figures 240-2 
    Image not available.

    A 32-year-old woman with type 1 diabetes developed large abscesses all over her body secondary to injection of cocaine and heroin. Her back shows the large scars remaining after the healing of these abscesses. (Courtesy of ­Richard P. Usatine, MD.)

    and 240-3; Abscess), cellulitis, septic thrombophlebitis, local induration, necrotizing fasciitis, gas gangrene, pyomyositis, mycotic aneurysm, compartmental syndromes, and foreign bodies (e.g., broken needle parts) in local areas.2
    • IDUs are at higher risk of getting methicillin-resistant Staphylococcus aureus(MRSA) skin infections that the patient may think are spider bites (Figure 240-4).
    • Some IDUs give up trying to inject into their veins and put the cocaine directly into the skin. This causes local skin necrosis that produces round atrophic scars (Figure 240-5).
  • IDUs are at risk for contracting systemic infections, including HIV and hepatitis B or hepatitis C.
    • Injecting drug users are at risk of endocarditis, osteomyelitis (Figures 240-6and 240-7), and an abscess of the epidural region. These infections can lead to long hospitalizations for intravenous antibiotics. The endocarditis that occurs in IDUs involves the right-sided heart valves (see Chapter 50, Bacterial Endocarditis).2 They are also at risk of septic emboli to the lungs, group A β-hemolytic streptococcal septicemia, septic arthritis, and candidal and other fungal infections.

 

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