Determination of the mechanical properties of normal and calcified human mitral chordae tendineae.

The aim of the present research is to determine the influence of the calcification of human mitral valves on the mechanical properties of their marginal chordae tendineae. The study was performed on marginal chords obtained from thirteen human mitral valves, explanted at surgery, including six non-calcified, four moderately calcified and three strongly calcified valves. The mechanical response of the chords from the non-calcified and moderately calcified valves was determined by means of quasi-static tensile tests (the poor condition of the strongly calcified valves prevented them from being mechanically characterised). The material parameters that were obtained and analysed (the Young's modulus, the secant modulus, the proportional limit stress, the ultimate strength, the strain at fracture and the density of energy stored up to maximum load) revealed noticeable differences in mechanical behaviour between the two groups of mitral chordae tendineae. Large scatter was obtained in all cases, nevertheless, considering the mean values, it was observed that the normal chords are between three and seven times stiffer or more resistant than the moderately calcified ones. On the contrary, the results obtained for the strain at fracture showed a rather different picture as, in this case, no significant differences were observed between the two families of chords. A scanning electron microscopy study was conducted in order to find out the relevant features of the calcium deposits present in the calcified chordae tendineae. In addition, the general aspects appreciated in the stress vs. strain curves were correlated with the collagen morphological evidences determined microscopically. Finally, the calcium content present in the three groups of chords was quantitatively determined through atomic absorption spectroscopy; then, the relation between the mechanical properties of normal and moderately calcified chords as a function of its calcium content was obtained. This analysis confirmed the existence of a strong correlation between calcium content and stiffness or resistance whereas the influence on the ductility seems to be negligible.

Mechanical properties of human coronary arteries.

The lack of reliable mechanical data on coronary arteries and, more specifically, on their wall strength hampers the application of numerical models and simulations to vascular problems, and precludes physicians from knowing in advance the response of coronary arteries to the different interventions. Studies of the mechanical properties of coronary arteries have been carried out almost exclusively on animals. Only a few studies have tried to characterize the in vivo behavior of human coronaries through tests under physiological conditions. In this work, the mechanical properties of human coronary arteries have been characterized. Whole samples from human right (RC) and left anterior descending (LAD) coronary arteries aged between 23 and 83 years have been studied by means of in-vitro tensile testing up to failure.

Surgical treatment of arterial ischemia associated with the use of the angioseal vascular closure device.

BACKGROUND: Despite the theoretical effectiveness of the Angio-Seal closure device to control bleeding after arterial puncture it can increase the risk of ischemia. OBJECTIVES: To describe arterial lesions caused by the device, surgical techniques needed to repair those lesions and surgical outcome in patients who underwent surgery for arterial ischemia after heart catheterization. PATIENTS AND METHODS: Seven patients underwent surgery over a period of 12 months at our institution. Five patients underwent emergency surgery and two a delayed procedure. The cause of ischemia was dissection of an atheroma plaque at the puncture site in four cases, dissection of the superficial femoral artery in one case, thrombosis of the common femoral artery in one case, and plication of the posterior arterial wall in one case. Arterial repair in these patients required the insertion of a vascular graft in three cases, endarterectomy plus angioplasty in two cases, endarterectomy plus graft interposition plus thrombectomy of the superficial femoral artery in one case and endarterectomy plus femoropopliteal bypass in one case. RESULTS: Treatment was successful in all patients. Mean follow up was 7.6 months (range 5-11 months). During the study period one patient died due to cardiopathy. No patients had to be re-operated and no limb losses were recorded. All the patients were asymptomatic from a vascular point of view with normal active lives for their age. CONCLUSIONS: Surgical repair is effective, although, generally, it is not restricted to a simple thrombectomy, requiring the use of different arterial repair techniques.

Endovascular repair of a ruptured giant popliteal artery aneurysm.

An 88-year-old woman with hypertension, chronic vein insufficiency, and repeated cellulites in the right lower extremity was admitted to our hospital with a new episode of right leg inflammation and edema associated with fever and leukocytosis. Due to unilateral enlargement of the leg and D-simer levels of 1000 microg/mL, a concomitant deep venous thrombosis was suspected and ultrasonography was performed. Color duplex-scanning found normal flow in the right deep leg veins but revealed an 11-cm-diameter popliteal artery aneurysm. A computed tomography scan confirmed the diagnosis and revealed a large perianeurysmal hematoma, and angiography provided evidence of perianeurysmal bleeding. The patient was unfit for open surgery, so an endovascular approach under local anesthesia was elected. The aneurysm was successfully excluded with an endograft, and 15 months after surgery, the patient is alive and had an uneventful postoperative course.

Endoluminal repair of a pseudoaneurysm in a patient with cryopreserved arterial allograft of the iliac vessel.

Prosthetic infection is one of the most serious complications of vascular surgery, and its treatment remains a surgical challenge. Good results have been reported using in situ replacement with arterial allografts, but late degeneration of the graft itself may necessitate further repair. We report a case of rupture and pseudoaneurysm formation of an iliac artery homograft urgently treated by endoluminal grafting with complete and immediate exclusion of the sac without complications. At 6-month follow-up angio-computed tomography showed patency of the vascular stent graft without leak evidence. Two years and 6 months after the procedure, the patient is well and alive.

Surgical site infections in cardiac surgery after a hospital catastrophe.

On 2 November 1999, one of the main hospital façades adjoining cardiovascular surgery collapsed in a 900-bed teaching hospital in Santander, Spain. The purpose of this study was to determine whether the accident affected the safety of patients by increasing the risk for nosocomial and surgical site infections (SSI). Measures for the prevention of nosocomial infections were immediately reinforced. A total of 217 consecutive patients were operated on before 2 November 1999, with another 296 after this date. Patients in both study periods showed similar severity of illness, complexity of surgical procedure and length of hospital stay. The overall rate of nosocomial infection before and after the accident was 28.1% and 24.7%, respectively (P=0.381). The rates of respiratory infection, urinary infection and bacteraemia were also similar. A statistically significant reduction in the SSI rate in the second period was observed (14.8% vs 4.4%, P=0.008). The collapse of the façade was not associated with any increase in nosocomial infection rates, but there was a significant reduction of SSI rates in relation to intensive infection control measures implemented after the collapse.

Evaluation of the Duke criteria in 93 episodes of prosthetic valve endocarditis: could sensitivity be improved?

BACKGROUND: Since publication of the Duke criteria for diagnosing endocarditis, several articles have confirmed their sensitivity when native and prosthetic valves are considered together. OBJECTIVES: To compare the differences between the older von Reyn criteria and the Duke criteria in prosthetic valve endocarditis only, and to determine if the latter's sensitivity could be improved by adding 2 minor criteria: new-onset heart failure and presence of conduction disturbances. METHODS: We retrospectively evaluated 93 episodes of prosthetic valve endocarditis from January 1986 to January 1998 in a teaching hospital, and then analyzed the 76 surgically confirmed episodes to compare the differences between the von Reyn and Duke diagnostic criteria. RESULTS: The von Reyn criteria rejected the diagnosis in 16 of the confirmed episodes, compared with 1 diagnosis missed by the Duke criteria and 1 missed using our suggested modifications. Definite diagnosis (Duke) was established in 60 episodes, compared with a diagnosis of probable (von Reyn) in 36 episodes (P<.001). Our modifications improved the sensitivity of the Duke criteria, diagnosing 70 episodes as definite (P = .02). CONCLUSIONS: As was the case with native valve endocarditis, the Duke criteria proved to be more sensitive than the von Reyn criteria in prosthetic valve endocarditis. The addition of 2 minor criteria (new-onset heart failure and presence of conduction disturbances) could improve the diagnostic sensitivity of the Duke criteria.

[The practical clinical guidelines of the Sociedad Española de Cardiología on interventional cardiology: coronary angioplasty and other technics]. / Guías de práctica clínica de la Sociedad Española de Cardiología en cardiología intervencionista: angioplastia coronaria y otras técnicas.

Interventional cardiology has had an extraordinary expansion in last years. This clinical guideline is a review of the scientific evidence of the techniques in relation to clinical and anatomic findings. The review includes: 1. Coronary arteriography. 2. Coronary balloon angioplasty. 3. Coronary stents. 4. Other techniques: directional atherectomy, rotational atherectomy, transluminal extraction atherectomy, cutting balloon, laser angioplasty and transmyocardial laser and endovascular radiotherapy. 5. Platelet glycoprotein IIb/IIIa inhibitors. 6. New diagnostic techniques: intravascular ultrasound, coronary angioscopy, Doppler and pressure wire. For the recommendations we have used the classification system: class I, IIa, IIb, III like in the guidelines of the American College of Cardiology and the American Heart Association.

The CarboMedics "Top-Hat" supraannular prosthesis.

BACKGROUND: The CarboMedics "Top-Hat" supraannular prosthesis was designed to permit the implantation of a larger prosthesis. METHODS: Between June 1993 and November 1996, 127 patients (average age, 61.8+/-10.2 years) received a CarboMedics "Top-Hat" supraannular aortic prosthesis. The average follow-up was 15.7 months, and all surviving patients underwent echocardiographic study. This group is compared with 656 patients in whom a standard CarboMedics prosthesis was implanted and also with 2,927 patients who received other aortic prostheses. RESULTS: Using the standard and the supraannular sizers, there was an average increase of one size in favor of the supraannular prosthesis: 18.9+/-2.8 mm standard versus 20.8+/-2.6 mm supraannular (p < 0.005). For each prosthesis size (19 to 23 mm), the body surface area of the patients in whom a CarboMedics supraannular prosthesis was implanted was significantly smaller than that in those who received a CarboMedics standard prosthesis or any other model. Hospital mortality was 3.9%, and late mortality was 5.5%. The actuarial survival was 86.5%+/-3.9% at 42 months. CONCLUSIONS: Using the CarboMedics supraannular prosthesis allows implantation of a larger prosthesis compared with the standard CarboMedics prosthesis or other models. This advantage is especially important in patients with a small aortic root.

[Coronary surgery associated with vascular disease]. / Cirugía coronaria asociada a enfermedad vascular.

Given the characteristics of ischemic heart disease, this condition is frequently associated with carotid and peripheral artery disease. Cardiac complications of vascular surgery and vascular complications of myocardial revascularization operations are common and severe. However, carotid artery endarterectomy or revascularization procedures for the lower extremities can be combined simultaneously with coronary artery bypass operations with acceptable results. It is difficult to determine whether or not both disorders should be treated surgically in a single stage or in two stages. This decision should be individualized according to the severity of the lesions and the risk of complications if one of these procedures is delayed.

Polymorphism of the platelet glycoprotein IIIa gene in patients with coronary stenosis.

Based on genetic variability, structural differences in the glycoprotein IIb/IIIa platelet receptor for adhesive proteins result in individual differences in the thrombogenicity of platelets. Recent studies suggest a controversial association between a genetic polymorphism of the glycoprotein IIIa gene (PlA2) and the risk of coronary artery disease. In our study, the prevalence of the PlA2 allele in a group of patients undergoing percutaneous coronary revascularization was 37%, a value significantly higher than in controls [13%, odds ratio (OR) = 3.93, 95% CI, 1.84 to 8.53] suggesting a significant association between this polymorphism and documented coronary stenosis, which is strongest among <60 years old patients (OR = 12.30, 95% CI, 2.98 to 70.93). This polymorphism represents an inherited risk factor for severe cardiovascular disease due to coronary occlusion.

Repair of nonsevere rheumatic aortic valve disease during other valvular procedures: is it safe?

OBJECTIVE: To investigate the long-term performance of aortic valve repair, we analyzed the results obtained in a 22-year period in patients who underwent repair of nonsevere rheumatic aortic valve disease during other valvular procedures. METHODS: Fifty-three patients (mean 40 +/- 11.6 years of age) with predominant rheumatic mitral valve disease had concomitant aortic valve disease in association with serious tricuspid valve disease in 25 of them. Preoperatively, aortic valve disease was considered moderate in 47.2% of the patients and mild in 52.8%. All patients underwent reparative techniques of the aortic valve (free edge unrolling, 44; subcommissural annuloplasty, 40; commissurotomy, 36) at the time of mitral or mitrotricuspid valve surgery. The completeness of follow-up during the closing interval was 100%, with a mean follow-up of 18.8 years (range 8 to 22.5 years). RESULTS: Hospital mortality rate was 7.5%. Of 49 surviving patients, 26 (53.1%) died during late follow-up. The actuarial survival curve including hospital mortality was 35.4% +/- 8.7% at 22 years. For patients who underwent mitral and aortic valve surgery, the actuarial survival curve at 22 years was 32.3% +/- 13%, whereas for patients who had a triple-valve operation the survival was 37.0% +/- 10.1% (p = 0.07). Twenty-five patients underwent an aortic prosthetic valve replacement. Actuarial free from aortic structural deterioration and valve-related complications at 22 years was 25.3% +/- 9.3% and 12.7% +/- 4.8%, respectively. CONCLUSIONS: Long-term functional results of reparative procedures of nonsevere aortic valve disease in patients with predominant rheumatic mitral valve disease have been inadequate at 22 years of follow-up. According to these data, conservative operations for rheumatic aortic valve disease do not seem appropriate.

Behavior of mitral allografts in the tricuspid position in the growing sheep model.

BACKGROUND: On the basis of a previous experience in a chronic sheep model in which partial mitral allografts remained viable and properly functioning 12 months after operation, we assessed the results obtained by replacing the tricuspid valve with fresh antibiotic-preserved mitral allografts. METHODS: Twenty 3-month-old sheep with a mean weight of 23.7 +/- 2.3 kg underwent cardiopulmonary bypass and had a fresh antibiotic-preserved mitral allograft implanted in the tricuspid position with the heart beating under normothermic conditions. The tricuspid valve apparatus was not excised. After a mean follow-up of 13.2 months, the allograft was evaluated by gross inspection and light and electron microscopy. RESULTS: Nine sheep died of technical causes within the first week after operation and 2 at 4 and 6 months of infective endocarditis of the allograft. The hemodynamic study before heart explantation revealed residual tricuspid incompetence in 3 of the 9 survivors. Macroscopic examination showed flexible valves with no signs of structural deterioration, calcification, or thrombosis. Under light and scanning electron microscopic examination, allografts were almost completely denuded of endothelial cells and showed loosely arranged connective tissue with scarce signs of inflammatory reaction. Despite these findings, allografts were free from major structural damage. CONCLUSIONS: The mitral homograft could be an alternative to replacement of the tricuspid valve with a bioprosthesis or a mechanical prosthesis.

The CarboMedics valve: experience with 1,049 implants.

BACKGROUND: The lack of valve rotatability, the structural deterioration, and the rate of valve-related complications with the standard mechanical bileaflet prosthesis led to the development of a new second-generation bileaflet valve in 1986. METHODS: Between January 1989 and March 1994, 1,049 CarboMedics valves were implanted in 859 patients. The rotatability was used in 109 mitral prostheses (21.5%) and in 61 aortic prostheses (11.6%). Follow-up was 97.1% complete, with 3,049 patient-years. RESULTS: The hospital mortality was 6.9% for the mitral group, 3.4% for the aortic group, and 10.7% for the double-valve group (p < 0.005). The actuarial survival curve at 5 years was 77.3% +/- 3.6%, 90.1% +/- 2.5%, and 79.2% +/- 3.7% (p = 0.0003), freedom from thromboembolism was 89.1% +/- 3.6%, 87.1% +/- 3.8%, and 68.8% +/- 8.2%, freedom from reoperation was 95.9% +/- 1.4%, 98.9% +/- 0.6%, and 94.9% +/- 2.4%, and freedom from valve-related complications was 68.8% +/- 4.1%, 79.5% +/- 3.5%, and 55.3% +/- 5.9% after mitral, aortic, and mitral and aortic valve replacement, respectively. There were five episodes of valve thrombosis, but no structural deterioration occurred. CONCLUSIONS: The clinical performance of the CarboMedics valve is quite satisfactory, with a low incidence of valve-related mortality and morbidity. The rotatability feature was useful when the native valve was preserved or for repeat valve replacement.

Poor clinical performance of the Wessex porcine heart valve bioprosthesis at nine years' follow up.

OBJECTIVE: To assess the long term performance of the Wessex porcine bioprostheses implanted in a consecutive series of patients. DESIGN: A retrospective case series. PATIENTS: Between January 1985 and July 1991, 184 Wessex bioprostheses (78 mitral, 102 aortic, and 4 tricuspid) were implanted in 150 patients. The patients were 55% (83/150) male and 45% (67/150) female; mean age was 60 (SD 10) years. RESULTS: Hospital mortality was 9.3% (14/150). Total follow up was 696 patient-years (mean 4.7 years per patient). Linearised rates (events per 100 patient-years (SEM) for postoperative complications for patients with isolated mitral valve replacement, isolated aortic valve replacement, and multiple valve replacement were, respectively: late mortality: 4.7 (1.6), 3.3 (0.9), and 4.9 (1.9); thromboembolism: 5.8 (1.8), 3.0 (0.9), and 2.8 (1.4); valve thrombosis: 1.0 (0.7), 0.3 (0.3), and 0.7 (0.7); structural failure: 5.8 (1.7), 1.9 (0.7), and 7.1 (2.2). Actuarial freedom from complications at nine years (70% confidence interval) was: late mortality: 61 (9)%, 57 (13)%, and 59 (12)%; thromboembolism and valve thrombosis: 71 (9)%, 79 (6)%, and 81 (8)%; structural failure: 33 (14)%, 50 (16)%, and 12 (14)%; all valve related morbidity/mortality: 31 (10)%, 21 (11)%, and 7 (9)%. Stent fractures appeared in 11 of 17 explanted prostheses; actuarial freedom from stent fracture at nine years was 66 (12)%. CONCLUSIONS: The Wessex bioprosthesis is associated with high thrombogenicity, early structural dysfunction, and a high valve related morbidity/mortality which justifies very close follow up of patients fitted with them.

Stent fracture in Wessex porcine heart valve bioprostheses.

By January 1994, a total of 40 Wessex porcine bioprostheses (21 mitral, 18 aortic, and 1 tricuspid) were explanted from 31 subjects. They belonged to a series of 150 patients who received 184 of such prostheses in our unit. Seventeen of these explanted prostheses were available for study, and 11 of them presented some sort of stent fracture or fissuring (mean of 3.6 +/- 1.6 fractures per prosthesis). The disruption occurred in all cases at the base of the commissural arch or at the commissural bar of the stent. The fractures were not detected clinically nor echo-cardiographically before reoperation, and most valves were explanted for reasons other than the stent rupture itself. The actuarial probability of freedom from stent fracture in our series is 66 +/- 12% at 9 years of follow-up. In our experience, fracture of the stent is an important mode of structural dysfunction of the Wessex porcine bioprostheses.