Significant increase of aortic root volume and commissural area occurs prior to aortic valve opening.

BACKGROUND AND AIM OF THE STUDY: The increased use of autologous, homologous or heterologous aortic root demands a detailed knowledge of its anatomy and function. The advent of 3-D digital sonomicrometry offered the opportunity to acquire precise information on the root and leaflet movements during the cardiac cycle. METHODS: Under cardiopulmonary bypass, sonomicrometry crystals were implanted in the aortic root and valve of eight sheep. Crystals were sutured at each commissure (n = 3), the top of the sinotubular junction (n = 3), lowest point of the annulus (n = 3), and leaflet tip (n = 3). 3-D coordinates of each crystal were recorded, together with left ventricular and aortic root pressures and ECG. When the animal had returned to a stable hemodynamic condition, the maximum and minimum distances between two crystals, and areas between three crystals, were calculated. Changes in root volume and leaflet position were time-related to the pressure changes. RESULTS: The most significant change between maximum and minimum distance between crystals during the cardiac cycle occurred at the commissural level. Similarly, the triangle defined by the three commissural crystals showed the greatest change in area (47%). The root volume increased by an average of 22%; about 40% of this increase occurred during the isovolumic phase. The aortic leaflets began to open before ejection. CONCLUSION: We postulate that aortic valve opening is initiated by the outward pull of the commissures. These findings should impact on aortic root surgery.

Behavior of vital and killed autologous pericardium in the descending aorta of sheep.

OBJECTIVES: Cardiovascular implants of fresh autologous pericardium produced mixed results including fibrosis with retraction or thinning and dilatation. The reasons for these differences are unknown but may involve activation of cells intrinsic to the tissue implant. To better understand the behavior of autologous pericardial implants, we studied the outcomes of vital pericardium (fresh) versus ethanol-killed pericardium. METHODS: Fresh and ethanol-killed autologous pericardium was transplanted as a patch, a conduit, or a rectangular flap bisecting the lumen in the descending aorta of sheep. The implants, recovered at 1, 5, 10, 15, and 30 days, were evaluated macroscopically and microscopically and by immunohistologic studies. RESULTS: Fresh implants showed good preservation with fibrin deposition on day 15. Microscopically, cells positive for alpha-actin and von Willebrand-related antigen appeared in the fibrin by day 10. By day 30 the flap was fibrotic and retracted whereas the patch and conduit retained their original appearance on the luminal aspect. An endothelium-like layer expressing von Willebrand-related antigen was present in the patch and conduit but absent in the flap. In contrast, the ethanol-killed implants were free of fibrin by day 10. By day 30, there were no signs of fibrosis or retraction, and a surface layer of cells expressing von Willebrand-related antigen, characteristic of endothelial cells, was present on all implants. All ethanol-killed implants were repopulated by host cells. CONCLUSION: The transluminal flap is an interesting model for studying the behavior of intraluminal autologous pericardial cardiovascular implants. Killing of the pericardial implants alleviated the fibrosis and tissue retraction observed with fresh flap implants.

Expanding indications for the Ross procedure.

The pulmonary autograft procedure has been shown to provide excellent hemodynamic results in young patients with aortic pathology. However, the use of this procedure in those with more complex aortic disease has not been extensively evaluated. The purpose of this report is to present the application of the Ross procedure in a 21-year-old man with extensive acquired aortic root pathology, both subannular and supraannular, and prosthetic valve dysfunction after two previous procedures.

Aortic root geometry: pattern of differences between leaflets and sinuses of Valsalva.

BACKGROUND AND AIMS OF THE STUDY: Growing interest in aortic root replacement with the use of stentless auto-, homo- and xenografts, and new developments in aortic valve conservation demand a deeper understanding of the normal aortic root anatomy. METHODS: Ten cryopreserved human aortic roots were pressurized, fixed and measured directly (leaflet free edge and attachment) and using three-dimensional computed tomography imaging software (sinus of Valsalva height and volume). RESULTS: The mean of the measurements of all four parameters yielded a pattern in which the non-coronary sinus (N) structures had the greatest dimensions followed by the right (R) and then the left (L). Non-parametric ANOVA on each of these parameters also showed significant differences among the sinuses yielding a pattern of N > R > L. This pattern determined an angle of tilt between the plane at the base (annulus) and the plane intersecting the sinotubular junction with a mean value of 11 degrees. Linear regression indicated that this angle did not depend on the size of the base (annulus). CONCLUSIONS: The data showed a geometric pattern of the aortic root, with the structures of the non-coronary sinus being the largest followed by the right and then the left. The possible hemodynamic relevance and surgical implications of these findings need to be explored.

Multiplane transesophageal echocardiography: a roadmap for mitral valve repair.

Multiplane transesophageal echocardiography (TEE) is useful in providing a detailed anatomic map for successful mitral valve repair. This report describes an approach, developed over the past two to three years, which helps to delineate valve anatomy in specific detail. Mid-esophageal views are selected to view different segments of the valve leaflets. When correlated with surgical anatomy, this approach is found to be both practical and useful.

Critical analysis of the Ross procedure: do its problems justify wider application?

The Ross procedure has shown superior hemodynamic results in young patients with aortic root pathology. Wider application of the procedure is restricted by its technical complexity and potential associated problems. The mortality/morbidity associated with 130 consecutive patients who have had the Ross procedure using the root replacement implantation technique between October 29, 1990, and October 8, 1998 is summarized. New York Heart Association (NYHA) preoperatively was class I, 23.5%; class II, 64.7%; and class III, 11.8%; mean age was 36 years (range 3 to 67 years). Men accounted for 73.8% and women 26.2% of the series. Preoperative diagnosis was congenital, 80.7%; rheumatic, 5.3%; failed prosthesis, 7.0%; degenerative, 2.6%; and endocarditis, 4.4% with preoperative aortic insufficiency (AI) 7.9% 1+, 19.8% 2+, 29.7% 3+, and 42.6% 4+, respectively. At operation mean cross-clamp time was 201 minutes (range 102 to 280 minutes). Patient follow-up was 99.2% (1 patient lost to follow-up), and 94.4% were NYHA class I at follow-up and 5.6% class II. Postoperative AI was 0 to 1 + in 93.6% and 2+ or greater in 6.4%. Mean time to patient follow-up was 436 days (range, 20 days to 2,878 days). Thirty-day mortality rate was 1.5%; one patient died of mediastinal bleeding, and one from complications of acute pancreatitis. There was no late mortality. Early autograft explant occurred in one patient secondary to iatrogenic injury to the pulmonary autograft at the time of harvesting, and one late explant occurred secondary to proximal suture line dehiscence. Late autograft repair occurred in one patient secondary to a false aneurysm along the proximal suture line; one patient was reoperated for left main coronary stenosis relative to iatrogenic injury at the time of the procedure. Right ventricular outflow tract replacement has occurred in two patients. Postoperative morbidity and mortality for the Ross procedure, as shown in this series, remains low and supports broader application of the procedure.

An in vitro study of the correlation between aortic valve diameter and mitral intertrigonal distance: a simple method to select the correct mitral annuloplasty ring size.

BACKGROUND AND AIMS OF THE STUDY: The application of the flexible Duran mitral annuloplasty ring in the treatment of various mitral valvular diseases is a physiologically appealing method of surgical repair. However, accurate identification of the trigonal structures, which is crucial in selecting the proper ring size, cannot always be made with certainty. A method is proposed to calculate the intertrigonal distance (ITD) from the aortic diameter. METHODS: Using digital calipers, the linear intertrigonal distance was measured in human homograft (n = 10) and sheep (n = 10) aortic root specimens. The aortic diameter was obtained from the circumference of the pressurized aortic root. A conversion factor was acquired for each specimen by dividing the aortic diameter with the measured ITD. A single constant conversion factor, which closely approximated the mean of the conversion factors in both groups, was then applied broadly to derive the ITD by calculation from the aortic diameter, which is known. The validity of using this constant conversion factor was tested by comparing the degree of variation of the calculated ITD from the direct measurements of the ITD. RESULTS: The mean of the conversion factors was 0.79 and 0.80 in the human and the sheep roots, respectively. The value 0.80 was used as the constant conversion factor in both groups for calculating the ITD. A paired comparison t-test in each group showed the difference between the calculated intertrigonal distance and the direct measurements of the ITD to be insignificant, validating the use of 0.80 as a constant conversion factor. CONCLUSIONS: The results of the study suggest that the conversion factor of 0.80 can be reliably used to obtain a calculated value of the intertrigonal distance; this method has the potential to aid the surgeon in determining the intertrigonal distance and the proper ring size.

Evolving experience with cryopreserved mitral valve allografts.

Allograft valves have been used for aortic valve replacement (AVR) for 35 years with excellent results. Early attempts at mitral valve replacement (MVR) with mitral valve allograft were unsuccessful mainly due to technical issues of measurement of appropriate graft size, difficulty of reimplantation, and early dehiscence of the papillary muscle anastomosis. Recently, interest in this procedure has been rekindled by successful laboratory experiments with mitral valve allograft implantation and improved understanding of the mitral valve apparatus from extensive mitral valve repair experience. In this article, we discuss the rationale for allograft use, the historical perspective of allograft use, and technical problems, along with current solutions and clinical outcomes of MVR with mitral valve allograft. Tricuspid valve replacement (TVR) with allograft mitral valve also is briefly discussed.

Cardiopulmonary response to maximal exercise in young athletes following the Ross procedure.

BACKGROUND: Aortic prosthetic devices offer limitations that make them less than optimal valve substitutes because the vast majority are innately obstructive, especially at increased levels of hemodynamic function. The present study is designed to demonstrate the hemodynamics of the pulmonary autograft in 11 conditioned athletes who have undergone the Ross (pulmonary autograft) procedure. Data was compared to a group of 13 age-matched "normal athletes." METHODS: All the Ross athletes had undergone the autograft procedure using the root replacement technique and were at least 3 months into their postrecovery phase. All athletes (both normal and Ross) underwent resting transthoracic echo followed by maximal exercise stress test (modified Bruce protocol) to exhaustion. Post-operative transesphogeal echocardiogram obtained within 90 seconds documented aortic valve gradient and velocity across the aortic valve. RESULTS: In the Ross athlete group, maximum heart rate was 188 beats per minute, peak aortic valve gradient at rest (mm Hg) 7.69 (mean), velocity across the aortic valve at rest (cm per second) 129.40 (mean), peak aortic valve gradient at maximal exercise (mm Hg) 16.30 (mean), velocity across the aortic valve at maximal exercise (cm per second) 190.00 (mean). In the normal athlete group, maximum heart rate was 176 beats/minute, peak aortic valve gradient at rest (mm Hg) 5.97 (mean), velocity across the aortic valve at rest (cm per second) 120.54 (mean), peak aortic valve gradient at maximal exercise (mm Hg) 14.61 (mean), velocity across the aortic valve at maximal exercise (cm per second) 190.23 (mean). CONCLUSION: The pulmonary autograft exhibits hemodynamic characteristics similar to the normal human aortic valve under conditions of enhanced cardiac output.

The Ross Procedure: current registry results.

BACKGROUND: The pulmonary autograft procedure for the treatment of aortic valve disease was developed and performed by Ross in 1967. The results he published in 1987 prompted increasing interest in the procedure. The International Registry of the Ross Procedure was established in 1993 to further examine longitudinal clinical outcomes. METHODS: The results from the Ross registry document the continued and growing interest in the procedure with 2,523 patients currently enrolled, representing 122 centers and 166 surgeons worldwide. RESULTS: Mortality (1987 to present) reported in the registry is 2.5%. It should be noted that follow-up stands at 70%. The most important issues for the registry to track are the incidence of reoperation for autograft failure and the fate of the pulmonary homograft. Reoperation for all valve-related problems is low (5.4%), with an autograft explant rate of 1.9%. Overall registry data indicate that the right ventricular outflow tract revision rate is 2.8%, with this decreasing by half to 1.3% in the 1987 to present subgroup. CONCLUSIONS: Rigorous analysis of outcomes is difficult with registry follow-up currently at 70%; however, the general conclusions derived from the registry are supported by other individual series with excellent follow-up. Success of the registry depends on judicious efforts by all participating surgeons and coordinators in documenting long-term patient results and reporting them to the registry.

Contrast echocardiography as an intraoperative method to determine the area of myocardium perfused by transmyocardial laser channels: an experimental study.

OBJECTIVES: Transmyocardial laser revascularization (TMLR) of the ischemic myocardium has been recognized as a potentially useful adjunct in the treatment of coronary arterial heart disease. Although there are methods to visualize the induced channels, they have been complex or concerned with long-term patency. The present work was designed as a feasibility study to determine whether contrast echocardiography could provide a simple and rapid method to assist the surgeon in determining the extent of the TMLR-treated area. METHODS: Transmyocardial channels were created in five Targhee adult sheep myocardium using a Holmium-YAG laser over the area supplied by the second diagonal branch. A commercially developed echocontrast agent (Optison) was injected into the left atrium. RESULTS: Passage of the dye through the myocardium was observed by epicardial echocardiography in all the animals. CONCLUSION: The current study shows that contrast echocardiography using a newer generation contrast agent capable of enhanced and persistent opacification of left ventricular cavity may serve as an effective tool in delineating intraoperatively the area of myocardium treated with TMLR.

Clinical aspects of the Ross procedure: indications and contraindications.

In the past decade, the pulmonary autograft procedure has emerged as the operation of choice for young individuals with aortic root pathology not amenable to repair. This is due in large part to the durability of the pulmonary autograft in the aortic position. Freedom from thrombosis and long-term anticoagulation also provide support for its application, as well as the pulmonary autograft's similarity to the human aortic valve. The present indications for the Ross procedure continue to broaden. Patient age is certainly a factor, with the upper limit being 50 years. Patients who present with mechanical or bioprosthetic aortic valve dysfunction also seem to be appropriate candidates for the procedure, as do those who present with active endocarditis. Athletes also are an appropriate subset based on the absence of anticoagulation and the extreme physiological and hemodynamic consequences of their chosen field. Contraindications to the Ross procedure include multivessel coronary artery disease as well as multiple pathology in which a second valve replacement device is required. Extremes of age and severely depressed left ventricular function also contradict application of the pulmonary autograft.

Ischemic mitral valve disease: classification and systemic approach to management.

One hundred sixty-nine consecutive patients with coronary artery disease and mitral valve pathology operated during the past 5 years were reviewed (98% follow-up). Eighty-seven patients underwent mitral valve repair and 82 mitral valve replacement with concomitant coronary artery bypass grafting (number of AV grafts = 3). An analysis of these patients (age range 48 to 92 [mean 69]) and a classification based on anatomic pathology of the mitral apparatus is presented. Flexible ring annuloplasty was utilized in all repairs and chordal-sparing techniques in all valve replacements. There was equal mortality for replacement and repair in this subset of high risk patients. Structural valve dysfunction of repaired valves was more common (5/81 [6.0]) than primary tissue valve failure after mitral valve replacement (0 patients).