In 2000, Bonhoeffer and colleagues12
performed the 1st percutaneous replacement of a failed pulmonary valve in a right ventricle-to-pulmonary artery prosthetic conduit. In the 1st clinical transcatheter aortic valve procedure, performed in 2002, Cribier and co-authors14
used the antegrade approach. This approach was chosen because their device required a 24F sheath (outer diameter, 26F), which would have been difficult to advance through the arterial system. However, the antegrade approach has several disadvantages, including the need for a transseptal procedure with the risk of perforation and cardiac tamponade; the need for an atrial septal defect to be created; the risk of advancing the wire through the mitral subvalvular apparatus; and the risk of rupturing the mitral valve during balloon inflation, especially if the wire is between the mitral chordae tendineae.
Ours is the 2nd report of percutaneous valve implantation in the aortic position. However, it is the 1st case to involve retrograde implantation of such a valve, thereby confirming the feasibility of this approach, which follows standard interventional techniques. By implanting the PHV percutaneously, we obtained a successful short-term therapeutic result in an otherwise hopeless situation. The cardiac arrest that occurred during the initial placement of the device in the aortic valve plane may have been related to outflow obstruction with a decreased blood supply to the coronary arteries in a patient with no cardiac reserve. Before valve implantation, the patient's cardiac output was incompatible with life. After device implantation, the patient recovered impressively. When he was in the intensive care unit, receiving inotropic and vasodilator support, his cardiac output increased dramatically, as did the valve area calculated with the Gorlin equation. The PHV functioned satisfactorily at all times, as confirmed by both transthoracic and transesophageal echocardiography. Even when the patient was hypotensive, the valve's opening and closing function was adequate.
The waist seen in the PHV after deployment was due to overexpansion of the borders of the stent (both upper and lower). Because there was no gradient across the valve and because intravascular ultrasonography showed good stent apposition to the aorta, no further dilation was attempted.
The cause of the patient's acute collapse after a period of significant improvement is unclear. We ruled out antegrade migration of the valve with coronary ostial obstruction, because this complication causes sudden death if the device occludes the left main coronary artery, or results in significant electrocardiographic changes if it occludes the right coronary ostium or both arteries. Retrograde migration causes severe mitral insufficiency, which was not seen on echo-Doppler studies. During TEE, the valve was seated in the aortic valve plane, both coronary ostia were visible, and no mitral insufficiency was detected. Across the PHV, 2-m/s jets were accompanied by early peaks, indicating a lack of significant obstruction.
Another possible explanation is sepsis, but the patient's temperature and white blood cell count were normal. Daily blood cultures also yielded negative results. At the time of collapse, the patient's pulmonary pressure increased from 60 to 90 mmHg. This clinical event suggests a pulmonary embolism as the most likely diagnosis. The patient's condition was too unstable for confirmatory testing. Thrombolytic agents were contraindicated because of the recent need for cardiopulmonary resuscitation.
The optimal anticoagulation regimen for use after PHV implantation still needs to be defined. Currently, it consists of heparin, followed by oral anticoagulant, antiplatelet therapy, or the two in combination.
In the treatment of valvular disease, the percutaneous route is a new approach that can be expected to benefit many patients in the future. At present, this procedure is limited to terminally ill patients who have severe aortic valve stenosis that is not amenable to surgical valve replacement. With time, further device modifications should allow transcatheter treatment of valvular disease to become a widely used technique.