Use of continuous retrograde gaseous oxygen persufflation for myocardial protection during open heart surgery.

PURPOSE: The infusion of a cardioplegic solution is the standard method of myocardial protection during open heart surgery. However, this method interrupts the surgical procedure and it is difficult to ensure a bloodless surgical field. To address these problems, the effect of continuous retrograde gaseous oxygen persufflation (ROP) on myocardial protection was assessed in comparison to St. Thomas' solution (STS). METHODS: Eighteen adult mongrel dogs were divided into three groups of six. Group G received continuous ROP, Group C received STS every 30 min, and Group N received hypothermia alone during the 120 min hypothermic ischemia. The myocardial metabolism was assessed by measuring the coronary sinus lactate concentration, lactate extraction ratio (LER), coronary sinus lipid peroxidation (LPO) concentration, left ventricular myocardial adenosine triphosphate (ATP) concentration, and water content. Cardiac function was assessed by the percent recovery relative to the baseline. RESULTS: In Group G, the lactate, LPO, and water content were significantly lower (P = 0.0062, P = 0.03, and P = 0.0065, respectively), and ATP was significantly higher (P = 0.028) than in Group C. The LER was only positive in Group G. In addition, the cardiac functions in Groups G and C were not significantly different. CONCLUSIONS: Retrograde gaseous oxygen persufflation was not inferior to STS in regard to myocardial protection. This technique could therefore represent a potentially promising cardioplegic method.

Surgical treatment for ischemic mitral regurgitation: strategy for a tethered valve.

Recently, ischemic mitral regurgitation (IMR) has been shown to be an individual risk factor for ischemic heart disease. The main mechanism of IMR is tethering of the leaflet secondary to left ventricular (LV) dilatation. In this situation, surgical treatment for IMR has been limited to ring annuloplasty with varying degrees of effectiveness. However, mid-term follow-up studies have shown that the results obtained with this approach are not satisfactory. Therefore, there has been a need to develop additional techniques to achieve more secure repair of IMR. The characteristics of the mitral leaflet configuration in IMR are apical displacement of the leaflets relative to the annulus, concavity of the leaflets, and a dilated annulus. Our basic strategy for a tethered mitral valve is rigid ring annuloplasty and inward correction of the outwardly displaced papillary muscle. For the latter correction, we employ the overlapping method or septal anterior ventricular exclusion (SAVE) procedure for LV volume reduction in cases of broad antero-septal infarction, or elevate the posterior papillary muscle by folding the LV wall at the root of the posterior papillary muscle via a small incision in the inferior wall in cases of infero-posterior infarction. An additional procedure is chordal cutting in combination with rigid ring annuloplasty and papillary muscle imbrication in combination with LV volume reduction. We have successfully combined these methods with the aid of detailed echocardiographic studies in individual patients. However, long-term follow-up will be necessary before this approach can be routinely adopted.

An experimental model of Stanford type B aortic dissection.

PURPOSE: To create an experimental model of aortic dissection with a long-lasting patent false lumen as a proper animal model for development of less-invasive treatment for aortic dissection. MATERIALS AND METHODS: Fifteen adult beagle dogs (weight, 10-12 kg) were used. The descending aorta was exposed by a left thoracotomy at the sixth intercostal space. The entry for the aortic dissection was created surgically just distal to the origin of the left innominate artery and the reentry was 5 cm distal to the entry point. Normal saline solution was injected into the aortic wall (ie, media) between these two points to create the dissection. The dogs were followed up at 1 day, 3 months, 1 year, and 2 years. RESULTS: All 12 surviving dogs had completely patent true and false lumina without any thrombi. Microscopic examination showed that the dissection was created in the tunica media layer, making it identical to aortic dissection in humans. Color Doppler imaging confirmed the patency of the true and false lumina and the relatively narrowed true lumen. CONCLUSION: In this canine model of aortic dissection, the false lumen has excellent long-term patency and the dissection plane is histologically similar to that in human aortic dissection. This model may contribute to the development of new treatments for Stanford type B aortic dissection.