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How to cite: Robicsek F. (1996). Left ventricular rupture following mitral valve replacement. The Journal of heart valve disease, 5(5), 571.

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How to cite: Peterffy, A., & Szabo, Z. (1996). Can mechanical valve prostheses be recommended in the tricuspid position?. The Journal of heart valve disease, 5(5), 570–571.

Calcification of the mitral annulus is always a technical complication in mitral surgery and standard procedures are often difficult to perform; mitral valve replacement can be dangerous with a high risk of perioperative heart rupture, and reconstructive surgery is often contraindicated. Nevertheless in this case of posterior leaflet prolapse with annular calcification valve repair was performed, after complete calcium debridement causing annulus disruption and atrio-ventricular discontinuity, by means of a straddling atrio-ventricular pericardial patch and the sliding leaflet technique.

How to cite: Arena, V., Repossini, A., Alamanni, F., Berti, M., Tamborini, G., Agrifoglio, M., & Biglioli, P. (1996). Straddling endoventricular pericardial patch in mitral valve repair with the sliding leaflet technique. The Journal of heart valve disease, 5(5), 567–569.

The authors report a case of tricuspid endocarditis complicating a congenital coronary artery fistula to the right ventricle in an eight-year-old female. The patient underwent valve replacement using a cryopreserved mitral homograft. Six months later, clinical and echocardiographic status are excellent. Using a mitral homograft for tricuspid endocarditis is a recognized approach in adults, whereas in pediatric cases it is exceptional. Homografts could prove to be a valid procedure in children when repair is not feasible, although one could expect a more rapid deterioration.

How to cite: Hvass, U., Lansac, E., Chatel, D., & Henri, I. (1996). Mitral homograft for tricuspid valve endocarditis complicating a congenital fistula between the right coronary artery and right ventricle. The Journal of heart valve disease, 5(5), 564–566.

The author presents the case of a patient treated surgically for extensive myocardial infarction causing development of ventricular aneurysm, perforation of the interventricular septum and mitral regurgitation using patch-correction of the ventricular aneurysm according to Dor, exclusion repair of the ventricular perforation and retrograde replacement of the mitral valve.

How to cite: Robicsek F. (1996). Surgical repair of extensive myocardial infarction: ventricular aneurysmectomy according to Dor with exclusion-closure of ventricular septal perforation and mitral replacement: a case report. The Journal of heart valve disease, 5(5), 561–563.

Background and aims of the study: In mitral valve (MV) reconstructive surgery, the most difficult problem is immediate, intraoperative assessment of the repaired valve. We describe a simple technique of assessing the MV after the repair while the left atrium (LA) is still open.

Methods: The heart is perfused through a coronary line, after frustrating the MV with a multiholed disposable chest tube, and made to beat while the aorta is declamped. After de-airing, the frustrator is removed and the coronary line flow is gradually increased to one third of the arterial pump output. Within the blood filled pericardial well, through the opened LA, the MV is assessed for competence. The method allows for taking any corrective steps to achieve a competent MV before proceeding further.

Results: Over the last 10 years, the method was used in 106 patients undergoing MV repair. It allowed us to take corrective steps in all 31 patients (29.2%) who were found to have significant mitral regurgitation. No complication which could be attributed to the method of testing was documented.

Conclusions: The method is found to be simple, safe, reliable, and has ensured against accepting less than optimal results.

How to cite: Shatapathy, P., & Aggarwal, B. K. (1996). Intraoperative assessment of mitral valve competence: a safe and reliable technique. The Journal of heart valve disease, 5(5), 558–560.

Background and aims of the study: Air embolism during open heart surgery seems to be a common occurrence and may be responsible for neuropsychological deficit or myocardial damage.

Material and methods: Forty-two consecutive patients undergoing valvular surgery were studied using the long axis view of the heart by two dimensional transesophageal echocardiography (TEE). The patients were randomized into two groups of 21 each. In group 1, the routine air evacuation method was used. In group 2, the same air evacuation method was used and controlled with a Doppler ultrasonic probe adjusted around the root of the aorta. At the end of air evacuation, intracardiac microbubbles and retained air were analyzed with TEE and when air was founded, its location was communicated to the surgeons who tried to remove it by shaking the heart and tilting the operating table for 15 minutes. The patients were assessed for detection of cardiac or neurological postoperative complications.

Results: The incidences of microbubbles and retained air were 57% and 43% in group 1, and 62% and 38% in group 2 respectively (ns). The mean grade of microbubbles was lower in group 2: 1.4 +/- 0.8 vs. 2.2 +/- 0.9, p < 0.05. TEE allowed to significantly decrease (p < 0.05) retained air and mean grade of microbubbles to 14% and 1.3 +/- 0.8 in group 1, and to 10% and 0.8 +/- 0.8 in group 2, without statistical difference between the two groups. Despite the help of TEE, manual attempts to eradicate retained air were unsuccessful in five patients (three in group 1, two in group 2).

Conclusions: The use of aortic ultrasonic probe allowed to reduce the amount of microbubbles. TEE was a useful tool not only for the detection of retained air but also for locating it, and guiding the procedure to eliminate it.

How to cite: Dalmas, J. P., Eker, A., Girard, C., Flamens, C., Neidecker, J., Obadia, J. F., Montagna, P., Lehot, J. J., Jegaden, O., & Mikaeloff, P. (1996). Intracardiac air clearing in valvular surgery guided by transesophageal echocardiography. The Journal of heart valve disease, 5(5), 553–557.

Background and aims of the study: An association between Graves' hyperthyroidism (G) and mitral valve prolapse (MVP) has been reported, but possible genetic linkage between the two disorders has not.

Methods: One hundred and five patients (pts) with G were studied after therapy, in a euthyroid state. MVP (auscultatory plus echocardiographic findings) was present in 33 pts (31%). Frequency of human lymphocyte antigens (HLA) in pts with G and in pts with G plus MVP was compared to 170 normal subjects (NL). There was no difference in HLA-A antigens among the three groups.

Results: The frequency of HLA B-15 was greater in pts with G plus MVP (18.9%) compared to NL (3%) and to G without MVP (4.2), p < 0.01. The frequency of HLA-B39 was greater in G without MVP (13.8%) compared to NL (4.1%), p < 0.01. The HLA DRB1*1601-2 was more frequent in G with (30.3%) or without (29.2%) MVP compared to NL (13.5%), p < 0.01. The frequency of HLA DRB1*1401-10 and DQA1*0104 were greater in NL (16.5%) compared to G with (3.0%) or without (4.2%) MVP, p < 0.01.

Conclusions: The data confirmed previous observations that the frequency of MVP is high in pts with G. Further, the data indicated a possible genetic linkage between the two abnormalities.

How to cite: Kontopoulos, A., Harsoulis, P., Adam, K., Papadopoulos, G., Polymenidis, Z., & Boudoulas, H. (1996). Frequency of HLA antigens in Graves' hyperthyroidism and mitral valve prolapse. The Journal of heart valve disease, 5(5), 543–547.

Background and aims of the study: Flexible trileaflet polyurethane heart valves can be designed which have good hydrodynamic function in vitro. The choice of polyurethane for fabrication of such valves is not simple; several similar polyurethanes are available, but relatively minor differences in their structure and composition may have profound effects on long term fatigue behavior with little effect on their short term mechanical properties.

Methods: The relative functional characteristics of flexible trileaflet polyurethane valves made from two different polyetherurethanes were compared before and after long term fatigue testing. The polyetherurethanes had similar gross mechanical properties, differing in that one was chain-extended with butanediol (PEU) and the other with ethylene diamine (PEUE). Six valves of each type, with similar leaflet thickness distributions, were studied.

Results: Hydrodynamic function of both valve types was similar to a similarly sized porcine aortic valve. Mean pressure drop across the open valve was higher in PEU valves than in PEUE valves, although PEUE valves had greater energy losses during closure and when closed. Reverse flow decreased with time in the fatigue tester. In long term fatigue tests, all six PEU valves failed by 307 million cycles, with failure primarily by development of holes at the coaptation region of the leaflets associated with localized calcification. Three PEUE valves exceeded 800 million cycles without failure and all PEUE valves exceeded 450 million cycles.

Conclusions: A combination of good phase separation of polyurethane soft and hard segments with good rubbery characteristics can explain the better results achieved in the PEUE valves compared with similar PEU valves. These results suggest the general type of polyurethane structure suitable for heart valve fabrication and have implications for development of novel polyurethanes for this application.

How to cite: Bernacca, G. M., Mackay, T. G., & Wheatley, D. J. (1996). In vitro function and durability of a polyurethane heart valve: material considerations. The Journal of heart valve disease, 5(5), 538–542.

Background and aims of the study: Most studies of mechanical heart valve prostheses in recent years have focused on the hydrodynamic and clinical performance of different valve designs. Little attention has been paid to the hemocompatibility (thrombogenicity) of materials used in the prostheses.

Methods: In the present study, three materials currently used in mechanical heart valves, titanium, cobalt-chromium alloy (Haynes 25) and pyrolytic carbon (Pyrolite), together with a surface-modified (methylated) titanium, were evaluated and compared for their hemocompatibility in a sheep model. The test materials in the form of discs were glued to plastic buttons and implanted into the intrathoracic venae cavae of anesthetized sheep. Four different materials were tested simultaneously in each animal: two in the superior and two in the inferior vena cava. Eight animals were used. After two hours of exposure to flowing blood, the discs were explanted and evaluated for their hemocompatibility using close-up photography and scanning electron microscopy (SEM). Thrombus formation and blood cell adhesion were studied quantitatively.

Results: The results showed that there was significantly more thrombus on pyrolytic carbon and methylated titanium than on titanium and cobalt-chromium (p < 0.05). More leukocytes adhered on pyrolytic carbon and cobalt-chromium than on titanium and methylated titanium (p < 0.05).

Conclusion: The results indicate that titanium and cobalt-chromium under the present condition were more hemocompatible than pyrolytic carbon. The clinical significance of the finding remains to be investigated.

How to cite: Yang, Y., Franzen, S. F., & Olin, C. L. (1996). In vivo comparison of hemocompatibility of materials used in mechanical heart valves. The Journal of heart valve disease, 5(5), 532–537.

Background and aims of the study: An in vivo method for testing hemocompatibility of materials used in mechanical heart valves was developed.

Methods: Discs of test materials were glued to specially designed plastic (Delrin) buttons and implanted into the superior and inferior venae cavae of sheep through a right thoracotomy. The button and disc had such configuration that the blood flow was minimally disturbed. Up to four different materials could be tested simultaneously in each animal: two in superior vena cava and two in inferior vena cava. The materials and their respective implantation sites were changed between different animals according to the Latin square principle. Ten animals were used. Three materials currently used in mechanical heart valve prostheses-titanium, cobalt-chromium alloy (Haynes 25) and pyrolytic carbon (Pyrolite)--together with a surface modified (methylated) titanium were evaluated. No heparin was given during the experiment. After two hours of testing the discs were explanted and evaluated for hemocompatibility. The thrombus area on each disc was measured with photography and planimetry. Platelet and leukocyte adhesion on the surfaces were quantitatively assessed by scanning electron microscopy (SEM). The results showed that there were significant differences in thrombus formation (p = 0.001) and leukocyte adhesion (p = 0.002) between the materials tested. There was no difference between implantation sites but significant differences between individual animals (p < 0.05).

Conclusion: The results indicate that the method can be used to evaluate early hemocompatibility of biomaterials.

How to cite: Yang, Y., Franzen, S., Tengvall, P., & Olin, C. (1996). An in vivo method for testing hemocompatibility of materials used in prosthetic heart valves. The Journal of heart valve disease, 5(5), 526–531.

Background and aims of the study: A new fixation method for bioprosthetic tissues is being developed, which does not utilize the standard glutaraldehyde treatment. This method, referred to as Ultifix, uses a coupler and a coupling enhancer with or without one or more coupling agents. It fixes the tissue by linking the amine and the carboxyl moieties through amide bonds either directly, or indirectly when coupling agents form bridges. The amide bonds thus formed are more stable than the Schiff-base bonds formed by glutaraldehyde. All compounds used during the fixation process and their by-products are water-soluble, and are easily removed by washing. In addition, the by-products are not toxic, as opposed to glutaraldehyde, which induces toxic reactions after implantation. The tests described in the manuscript were specifically aimed at evaluating the cross-linking efficacy of the process on heart valve tissues, as well as their resistance to calcification in the rat model.

Methods: Porcine aortic roots and porcine pericardium were fixed using the coupling agents 1,6-hexane diamine (DIA) and suberic acid (SUA) in the presence of the coupler 1-ethyl-3(-3 dimethyl aminopropyl) carbodiimide hydrochloride (EDC) and the coupling enhancer N-hydroxysulfosuccinimide (sulfo-NHS). The tissues were then evaluated for their resistance to thermal denaturation, to enzymatic digestion, and to calcification when implanted subdermally in rats for two, four, eight and 16 weeks.

Results: The results demonstrate that the cusps and the wall of porcine aortic roots, and porcine pericardium, are as well stabilized and as cross-linked by Ultifix as they are by the standard glutaraldehyde method. In addition, the cusps of the porcine aortic root and the porcine pericardium, but not the wall of the porcine aortic root, calcify minimally and significantly less when implanted subdermally for up to 16 weeks in three week old rats than the control material fixed with glutaraldehyde.

Conclusion: The Ultifix process of cross-linking bioprosthetic heart valves may thus be a good alternative to the standard glutaraldehyde process of fixation, with increased durability and without toxic effects.

How to cite: Girardot, J. M., & Girardot, M. N. (1996). Amide cross-linking: an alternative to glutaraldehyde fixation. The Journal of heart valve disease, 5(5), 518–525.

Background and aims of the study: Complications after replacement of diseased heart valves with mechanical prostheses may be related to fluid dynamic disturbances. Magnetic resonance velocity mapping may allow quantitative, non-invasive, serial assessment of the blood velocity distribution around prosthetic heart valves in patients.

Material and methods: Velocity mapping was performed in six patients with aortic St. Jude Medical valves. Axial velocity components were measured at three positions near the valve and correlated with earlier in vitro results and with earlier invasive measurements.

Results: The velocity profiles downstream of the valve prostheses reflected the valve design and thus confirmed previous findings. In the one diameter downstream position blood flow velocities accelerated initially through the lateral orifices of the valve. Later in the acceleration phase the velocity profile became skewed and the antegrade velocity components increased in the part of the vessel corresponding to the central slit of the valve. Retrograde velocities occurred in part of the lateral orifice regions.

Conclusions: MR velocity mapping provides valuable information on velocity fields around prosthetic bileaflet aortic valves. The velocity fields from the present study disclose qualitative similarity to those previously obtained. The present study, however, suggests a more skewed velocity profile than predicted from former studies. More extensive studies on larger patient groups should be performed, also with other valve types in order to establish a bank of reference data.

How to cite: Houlind, K., Eschen, O., Pedersen, E. M., Jensen, T., Hasenkam, J. M., & Paulsen, P. K. (1996). Magnetic resonance imaging of blood velocity distribution around St. Jude medical aortic valves in patients. The Journal of heart valve disease, 5(5), 511–517.

Background and aims of the study: This communication reports the anticoagulant-related complications (ARH) in patients who received the St. Jude Medical mechanical prosthesis and were 70 years of age or older at the time of implantation.

Methods: Our institutional data file shows that during the 15-year period from 1977 to 1992, our group implanted the St. Jude Medical mechanical prosthesis in 610 patients with aortic valve disease (AVR) and 186 patients with mitral disease (MVR), who were 70 years or older, either with or without coronary artery bypass grafts. The operative mortality was 6.4% for AVR and 16% for MVR. The mean follow up for this elderly group was 4.9 years (2,996 patient-years) for AVR and 4.2 years (771 patient-years) for MVR.

Results: The incidence of late death was 30% for AVR and 33% for MVR. The freedom from TE was 91.6% +/- 1.8%, from valve thrombosis 98.8% +/- 0.7%, and from ARH 95.9% +/- 1.1%. The freedom from operative death, valve-related death, and all complications was 78.8% +/- 2.4%. The data from this study shows that both the aortic and the mitral valve replacement patients who were 70 years or older have an acceptable rate of bleeding complications. Reduction of the intensity of anticoagulation in our practice (INR of 1.8-2.5 for AVR and 2.5-3.2 for MVR) may play a role in this finding. The incidence of valve thrombosis and TE rates were also low in this study.

Conclusions: With increasing life expectancy in the elderly, the use of the St. Jude Medical Mechanical prosthesis and low intensity anticoagulation could be reconsidered for a selected group of elderly patients.

How to cite: Arom, K. V., Emery, R. W., Nicoloff, D. M., & Petersen, R. J. (1996). Anticoagulant related complications in elderly patients with St. Jude mechanical valve prostheses. The Journal of heart valve disease, 5(5), 505–510.

Background and aims of the study: The traditional method of aortic valve replacement with a homograft has been free-hand insertion in the subcoronary position. Recently, total root replacement has become increasingly popular. We present our experiences with both methods in this study.

Material and methods: Between January 1, 1987 and March 31, 1996, 208 patients underwent homograft replacement of the aortic valve (free-hand subcoronary technique, n = 147 and root replacement, n = 61). The age of the patients ranged between 1.5 and 78 years with a mean age of 41 years. There were 55 females and 153 males. Ninety-four patients had infected aortic root (with 47 ring abscesses) and 114 patients had sterile aortic roots. In these series, patients with small aortic root, complicated endocarditis, dilated aortic annulus and aneurysm received aortic root replacement.

Results: The hospital mortality of patients with non-infected and infected roots was 2.6% and 8.5% respectively making an overall hospital mortality of 5.2%. In patients with free-hand subcoronary valve implantation (AVR) and root replacement (ARR) techniques the hospital mortality was 3.4% and 9.8% respectively. The major risk factor for death was New York Heart Association functional class IV with sepsis. Eight years patient survival in patients with AVR and ARR was 95% +/- 2% and 86% +/- 4% respectively. Freedom from structural deterioration in patients with AVR and ARR was 96.5% +/- 2% and 98% +/- 3% whereas freedom from reoperation was identical 94% +/- 2% and 93% +/- 4% respectively. However, the incidence of reoperation in patients under 40 years of age, particularly in children (< 16 years of age) during the eight years' follow up was 27%. The rate of recurrent endocarditis was 3.6% in ARR patients and development of postoperative pseudoaneurysm formation occurred in 1.4% of AVR patients with endocarditis.

Conclusion: In conclusion, ARR technique provides low rate of reoperation in the early postoperative period. Cryopreserved homografts in the subcoronary position in adult patients < 40 years of age showed excellent medium term durability and hemodynamic performance providing evidence that long term outcome with a meticulous subcoronary implantation technique is comparable to that with the ARR technique.

How to cite: Yankah, A. C., Weng, Y., Hofmeister, J., Alexi-Meskhishvili, V., Siniawski, H., Lange, P. E., & Hetzer, R. (1996). Freehand subcoronary aortic valve and aortic root replacement with cryopreserved homografts: intermediate term results. The Journal of heart valve disease, 5(5), 498–504.

Background and aims of the study: Ninety-one of 351 patients who received an aortic valve replacement (AVR) with the St. Jude Medical (SJM) valve at the Royal Melbourne Hospital between 1978 and 1990 were 50-year-old or younger. The results of these patients were retrospectively analyzed so that comparison may be made with the long term results of homograft AVR.

Material and methods: There were 75 males and 16 females. Mean age was 39 years (range 15-50 years). Valve pathologies were, congenital (32), degenerative (30), rheumatic (20), infective endocarditis (7). All patients had warfarin post-operatively.

Results: Follow up was complete with a total of 689 patients years, (range 34 months to 14.75 years, mean 7.6 years). There were two operative deaths (2.2%) and three late deaths (0.5 +/- 0.3%/patient-year) and two have undergone subsequent cardiac transplantation. Seventy-eight of 86 survivors (91%) are in NYHA functional Class I. At 10 years, actuarial survival was 94 +/- 2.9%, freedom from embolism was 96.4 +/- 2.4%, and from anticoagulant (AC) hemorrhage 89.4 +/- 6.5%. There were no structural failures; four cases paravalvular leaks were reported. Freedom from non-structural deterioration at 10 years was 95.3 +/- 2.3%. Freedom from reoperation was 95.6 +/- 3.2% at 10 years. Linearized rates (% per patient-year) were for embolism 0.6 +/- 0.5, AC hemorrhage 0.8 +/- 0.2, non-structural dysfunction 0.8 +/- 0.2 for endocarditis 0.4 +/- 0.5, and for reoperation 0.4 +/- 0.4.

Conclusions: The SJM valve prosthesis has performed well in the aortic position in this younger group of patients up to 10 years.

How to cite: Tatoulis, J., Chaiyaroj, S., & Smith, J. A. (1996). Aortic valve replacement in patients 50 years old or younger with the St. Jude Medical valve: 14-year experience. The Journal of heart valve disease, 5(5), 491–497.

Background and aims of the study: Although chordal-sparing mitral valve replacement (MVR) is popular, the optimal tension for preserved or reattached chordae tendineae (CT) or for synthetic (ePTFE) CT is unknown.

Methods: Changes in left ventricular (LV) systolic and diastolic function in nine dogs with anterior CT preservation with different levels of end-diastolic chordal tension (0, 10, 20, 30, and 40 gm, measured by spring scale) were compared using an isovolumic double-balloon technique.

Results: LV function data at each level of tension were compared to control data using 0 gm of tension. Systolic function assessed as Emax (mmHg/ml) at 10, 20, 30, and 40 gm versus control was: 5.7 +/- 2.6/4.9 +/- 2.7, 4.7 +/- 2.2/4.7 +/- 2.7, 4.8 +/- 3.1/4.7 +/- 2.8, and 5.0 +/- 3.5/5.1 +/- 2.9; delta improvement from the control at 10 gm was larger than that at 20 gm (p < 0.05 by paired t-test). Diastolic function assessed as diastolic stiffness (Sd, mmHg/ml) at the same CT tensions versus control was: 0.56 +/- 0.23/0.56 +/- 0.34, 0.53 +/- 0.30/0.57 +/- 0.37, 0.56 +/- 0.39/0.52 +/- 0.38, and 0.60 +/- 0.36/0.58 +/- 0.39; delta Sd was smaller at 20 gm than at 30 gm (p = 0.05 by ANOVA). LV equilibrium volume (Veq, ml) was: 10.7 +/- 3.9/10.1 +/- 3.9, 9.6 +/- 3.4/9.9 +/- 3.8, 10.8 +/- 4.0/10.3 +/- 3.4, and 10.6 +/- 4.0/10.6 +/- 3.5; delta Veq was larger (i.e., more compliant chamber) at 10 gm than at 40 gm (p < 0.05 by rm-ANOVA). Arrhythmias precluding satisfactory measurements occurred in two dogs at 30 or 40 gm CT tension.

Conclusions: With chordal tension exceeding 10 gm, which is barely palpable, there was no additional enhancement in LV systolic function compared to zero CT tension. Veq was largest at the lowest tension; LV diastolic function (assessed as Sd) deteriorated with tensions of 30 gm or higher. The optimal end-diastolic tension of preserved CT should enhance systolic LV performance without adversely affecting diastolic function; in this isovolumic model, minimal CT tension (10 gm) best met these goals. Excessive tension may negate the potential hemodynamic benefits of chordal preservation during mitral valve replacement.

How to cite: Komeda, M., DeAnda, A., Jr, Glasson, J. R., Bolger, A. F., Nikolic, S. D., Ingels, N. B., Jr, & Miller, D. C. (1996). Improving methods of chordal-sparing mitral valve replacement--Part II: Optimal tension for chordal resuspension. The Journal of heart valve disease, 5(5), 477–483.

Background and aims of the study: Mitral homograft replacement requires a good knowledge of the anatomy of the papillary muscles. Clinical experience with mitral homografts has revealed an as yet unexplored aspect of the morphology of the mitral subvalvular apparatus, that is correspondence between papillary muscle sub-divisions and chordal attachment to the leaflets.

Methods: To further our understanding we subjected 65 normal hearts to close scrutiny which confirmed our perioperative observations.

Results: We could establish a classification based on the ways that the papillary muscles relate to the leaflets via the chordae. Four types are described. In type I the papillary muscle is single. In type II the papillary muscle has two heads, one of which sends chordae exclusively to the posterior leaflet. In type III the papillary muscle is also divided, one head supporting the commissural area exclusively. Type IV PM resembles type III but is distinguished from it in the way that the head supporting the commissure is very short. In this type the different heads also originate at different levels on the ventricular wall from the apex to the base.

How to cite: Ramsheyi, S. A., Pargaonkar, S., Lassau, J. P., & Acar, C. (1996). Morphologic classification of the mitral papillary muscles. The Journal of heart valve disease, 5(5), 472–476.

Background and aim of study: While the structure and function of heart valve cusp collagen have been relatively well defined, the role and morphology of elastin remains poorly understood, despite the fact that it comprises up to 13% of the cusp dry weight.

Material and methods: The elastin structure of 24 hot-alkali-digested porcine aortic valve cusps was investigated with scanning electron microscopy. Elastin structures were categorized according to their morphology and a model of the distribution of these structures within the cusp was developed.

Results: The two main types of elastin observed, amorphous and fibrillar, were further categorized based on their morphology. Amorphous structures included continuous sheet, sheet with integrated fibers on the surface and sheet with fenestrations. Fibrillar structures identified were loose fibers, loose mesh/woven fibers and compact mesh. By imaging samples of digested fibrosa and ventricularis that had been microdissected apart, we were able to produce maps of the elastin structure in the two layers. The ventricularis contains a large continuous sheet of amorphous or compact mesh elastin that covers the entire layer. Elastin in the fibrosa is much more complex, consisting of large tubes that emerge from the aortic attachment and extend circumferentially across the cusp. The tubes, constructed of amorphous fenestrated sheet and loose mesh elastin, likely surround the large circumferential collagen bundles observed in the fibrosa.

Conclusions: The elastin structures that we have identified help explain the measured mechanics of this tissue and suggest that collagen and elastin are highly integrated. As a result, we believe that elastin plays an important functional role in the cusp and that a full explanation of heart valve cusp mechanics must incorporate the contributions of both collagen and elastin.

How to cite: Scott, M. J., & Vesely, I. (1996). Morphology of porcine aortic valve cusp elastin. The Journal of heart valve disease, 5(5), 464–471.

Background and aims of the study: The optimal direction to preserve artificial chordae tendineae (CT) during mitral valve replacement (MVR) is not known, especially in regard to the response to inotropic stimulation which simulates exercise conditions.

Methods: Using a non-distorting isovolumic balloon technique, we compared left ventricular (LV) systolic and diastolic mechanics in 11 dogs in a control state (no chordal sparing) and with four different methods of chordal preservation: posterior, anterior, oblique (anterior papillary muscle chordae directed anteriorly and others posteriorly, the direction which theoretically augments LV systolic twist), and counter-oblique (counter, chordae preserved in directions opposite to oblique).

Results: Before dobutamine, delta Emax from the control was: 0.32 +/- 0.82, 0.10 +/- 0.43, 0.64 +/- 1.07, and 0.51 +/- 0.78 (anterior, posterior, oblique, and counter method, respectively). With dobutamine (3 mg/kg/min), delta Emax (mmHg/ml) was: 0.41 +/- 1.21, -0.13 +/- 0.75, 0.59 +/- 0.82*, and -0.34 +/- 0.71. Before dobutamine, delta LV stiffness (Sd, mmHg/ml) was -0.01 +/- 0.09, -0.02 +/- 0.12, 0.02 +/- 0.10, and 0.01 +/- 0.12; with dobutamine it was 0.01 +/- 0.09, 0.00 +/- 0.15, 0.03 +/- 0.15, and -0.06 +/- 0.11. Similarly, before dobutamine delta LV equilibrium volume (Veq) was -1.2 +/- 3.8, -0.3 +/- 3.0, -0.7 +/- 2.7, and -0.2 +/- 3.5, whereas with dobutamine zeta eq was -0.1 +/- 1.1, -0.4 +/- 0.8, 0.6 +/- 1.7, and -0.4 +/- 1.1. (Mean +/- S.D.; *p = 0.005 posterior and counter by ANOVA; p = NS (< 0.06) versus counter and posterior by ANOVA).

Conclusions: The oblique method enhanced systolic LV function both with and without dobutamine, while a tendency towards better diastolic LV function (Veq) was observed with dobutamine. The anterior method was next best in preserving systolic function, both with and without dobutamine. LV diastolic function tended to deteriorate with dobutamine in the posterior group. Systolic function with the counter method deteriorated with dobutamine. These results warrant further study in an ejecting model to investigate LV systolic and diastolic mechanics with the oblique method of CT preservation, including interactions with LV systolic twist and diastolic recoil.