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For Referring Physicians April 2000 Aneurysms Aneurysms are like the soft spot on the inner tube of a tire (for those of us who are old enough to remember when there were such things) or like the weak spot in the wall of a balloon. They can occur in any artery, but are most frequently seen in the aorta and iliacs, the femorals, or the popliteal arteries. They are a consequence of hardening of the arteries. Aneurysms are often mentioned in the cerebral arteries, but these are a different variant and not associated with atherosclerosis. The diagnosis of aneurysms should be easy since they are larger than the normal blood vessels; all you have to do is feel them (unless your patient comes from York County). Actually even in some quite obese abdomen, one can sense a pulsation on deep palpation of the abdomen. The key though is to have a high enough index of suspicion to consider them when the pulsation, but no real mass is felt. Femoral aneurysms are the easiest to diagnose since the femoral vessels are close to the skin and easily palpable in any body habitus. Popliteal aneurysms are the most challenging since they occur behind the knee and palpation of the popliteal artery is difficult for most of us. The rule of thumb is that if you can easily palpate the popliteal artery, scan it to rule out an aneurysm. Confirmation of aneurysms can be done in several says. Plain x-rays may show the outline of the aneurysm by calcification of the walls. This, however, does not prove an accurate measurement. We prefer duplex scanning because it is quite accurate and is the cheapest and easiest study that can be done. It is accurate to within a millimeter or two and quite reproducible and also radiation free. Duplex scanning is the procedure of choice for the initial diagnosis and periodic follow up for changes in aneurysm size. CT scanning is also quite accurate, but much more expensive. It is a good modality for following a thoracic or upper abdominal (suprarenal) aneurysm where the presence of air may interfere with the sound wave transmission of the duplex scan. CT scanning is also the preoperative gold standard in planning intervention when indicated. MRI is capable of demonstrating aneurysms, but is even more expensive and rarely indicated. Angiography was used in the past, but is rarely indicated now since it will show only the moving blood and not the thrombus within the aneurysm (since blood wants to flow in a straight line, the expanding walls of the aneurysm become filled with thrombus). Aneurysms have different incidences of complications. Rupture and embolization is possible in all aneurysms. The peripheral ones (femoral and popliteal) will usually embolize, but rarely rupture. Abdominal aortic aneurysms have rupture as their most common and serious complication. The incidence of rupture is directly related to the size being low in the 4 cm aneurysms and up to 50% for those measuring 6 cm or more. Most vascular surgeons prefer to follow small aneurysms until they approach 5 cm in size and then recommend repair. We follow them closely in the Vascular Laboratory for signs of progression and enlargement. Repair of aneurysms has an exciting new twist since the release of endovascular grafts. Formerly, the only modality available was the standard open repair with its attendant large incision and significant hemodynamic changes. Now, if a patient's anatomy is appropriate, it may be possible to repair the aneurysm endovascularly with femoral artery cutdowns and insertion of a graft over guide wires on the inside of the aneurysm. As more grafts become available and they become more adaptable to the individual patient's anatomy, this option will be chosen much more frequently. We have recently been certified for insertion of the Ancure™ endovascular graft and are anxiously awaiting further refinements in this technology. It is estimated that within the next five years the majority or even up to 80% of aneurysms will be repaired endovascularly. Thank you for your continued support! |
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