He Ping Zhang

Comparison of lnoue single-balloon versus double-balloon technique for percutaneous mitral valvotomy

The results of percutaneous mitral valvotomy by means of the Inoue single-balloon (N = 85, group 1) and the double-balloon (N = 322, group 2) techniques were compared in a nonrandomized study. The groups were not significantly different with regard to age, sex, calcification, or hemodynamic values before percutaneous mitral valvotomy. After percutaneous mitral valvotomy, patients in both groups had significant hemodynamic and clinical improvement. The increases in mitral valve area and cardiac output and the decreases in mitral valve gradient, mean pulmonary artery pressure, and mean left atrial pressure were greater in group 2. Mitral valve area determined by the Gorlin method increased 191% in group 2 and 106% in group 1; Doppler-determined mitral valve area increased 133% in group 2 and 98% in group 1. Optimal results were achieved in 93% of the patients in group 2 and 76% in group 1 (p less than or equal to 0.0001). In group 1, 6% of patients had a left-to-right shunt as shown by angiography versus 14% in group 2 (p less than or equal to 0.05). In group 2, 46% of patients had at least a 1+ increase in mitral regurgitation versus 52% in group 1. Among the patients who had an increase in mitral regurgitation, 36% of those in group 1 versus 9% in group 2 had a 2+ or more increase (p less than or equal to 0.001). The mean balloon diameter to anulus ratio was larger in group 2, and the larger the balloon diameter to anulus ratio, the greater the increase in mitral valve area.(ABSTRACT TRUNCATED AT 250 WORDS)

A Novel Method for Treatment of Abdominal Aortic Aneurysms Using Percutaneous Implantation of a Newly Designed Endovascular Device

BACKGROUND Percutaneous implantation of a stent to bridge abdominal aortic aneurysm (AAA) may provide an alternative to surgical reconstruction in patients with this serious disorder. We developed a self-expandable, stainless steel, woven mesh endovascular device with a delivery catheter and studied its efficacy in a canine model of AAA. METHODS AND RESULTS Infrarenal AAAs were created surgically in eight adult dogs using autologous tissue. Two types of endovascular stents were used in this study; a plain or uncovered stent, about 14 mm in diameter in the unconstrained configuration, and a covered stent, coated by porous polyurethane, about 16 mm in diameter. All stents were successfully placed on the first attempt. Aortograms revealed a mean aneurysm diameter of 1.86 +/- 0.47 cm, an average of 70% larger than the reference aortic lumen before stent placement. After stent placement, aortograms showed that the aneurysmal cavity disappeared completely in three dogs treated with a covered stent and that the aortic blood flow into the cavity markedly reduced, with faint contrast filling the cavity in the remaining five dogs treated with an uncovered stent. The uncovered stent was intentionally placed across the major arterial branches in two dogs. No acute complications were encountered at the time of stent placement. Two dogs were killed shortly after the procedure for immediate evaluation of the device, which was found to be in place and patent. One dog in which a covered stent was placed was euthanized 2 1/2 weeks later because of paraplegia secondary to a spinal cord infarction noted 48 hours after stent placement. Postmortem study revealed thrombus occluding the stent lumen. The remaining five dogs tolerated the devices well and completed 4 weeks of follow-up. Premortem aortograms showed no residual aneurysmal cavity in four dogs and only a small cavity in one dog that had received an uncovered stent. All stents were fully patent with no thrombus and were either completely or partially surfaced by neointima. Importantly, the major arterial branches over which the uncovered stents were placed were widely patent without obstruction by neointima. CONCLUSIONS This study demonstrates the feasibility of percutaneous implantation of this new device and its effectiveness in the treatment of surgically created AAA in our canine model. The covered stent was able to exclude AAA immediately upon deployment and is of potential value in the emergency treatment of leaking AAAs. The uncovered stent appears to safely bridge branch arteries as well as significantly reduce the angiographic size of the aneurysm and may be useful in the elective therapy of AAAs. These results are promising, and future clinical trials to investigate the safety and efficacy of this device in humans are warranted.

Balloon valvotomy for mitral stenosis associated with moderate mitral regurgitation

In summary, the possibility of developing moderate to severe (3+) MR after balloon dilatation was greater in patients with preexisting moderate MR. Nevertheless, improvements in hemodynamics and increases in mitral valve area can be equally achieved using balloon mitral valvotomy for treatment of mitral stenosis in patients with or without moderate MR.

Spontaneous rupture and thrombotic effects in a swine model of untreated abdominal aortic aneurysms

BackgroundIn our previous canine model of abdominal aortic aneurysm, although aneurysm growth was observed, the aneurysms did not rupture. This prompted us to develop a swine model, which has the advantage of fibrinolytic and coagulation systems similar to those found in humans.MethodsWe simulated aneurysms by connecting fascia pouches to the aorta. In nine pigs, two pieces of fascia (5 × 8 cm each) were sutured to the posterior surface of the aorta. After the lateral edges of the aorta were sutured together, the aorta was clamped below the renal arteries and at the aortic bifurcation. We then resected a piece of aorta within the pouch, clamped the pouch below the open roof, and unclamped the aorta. When the entire pouch had been sutured, the last clamp was removed and blood flowed into the “aneurysm.” The total aortic cross clamp time was between 4 and 25 minutes.Results“Aneurysm” size ranged from 3.0 × 2.5 cm to 7.5 × 4.0 cm (length × width). Aneurysm rupture occurred in seven pigs between 4 and 43 days after initial surgery; however, rupture never occurred at a suture site. Aneurysm size at rupture was two to four times greater than that of the original pouch. We found thrombus in all of the aneurysms examined more than 2 days after surgery. Histology revealed aneurysm walls that were thicker than the fascia. Although fascia segments could be identified because of their characteristic trilayer of thick collagen fibers, most of the aneurysm wall contained thin collagen fibers. These observations are consistent with new collagen production.ConclusionWe constructed a swine model of abdominal aortic aneurysm that possessed the features of growth and rupture necessary to simulate human aneurysms. Our method will allow techniques designed to isolate aneurysms from the circulation to be tested in a model with a fibrinolytic system similar to that of humans.