Aortic valve replacement with pericardial valves in patients with small aortic roots. Clinical results in a consecutive series of patients receiving 19 and 21 mm prostheses.

OBJECTIVE: To determine how second generation pericardial valves perform in patients with small aortic roots. DESIGN: Ninety patients who underwent isolated aortic valve replacement (AVR) with 19 or 21 mm Mitroflow or Carpentier-Edwards (Perimount) valves between 1989 and 1996 were studied. Mean age was 78 years. Concomitant coronary bypass surgery was performed in 41%. RESULTS: Thirty-day mortality was 5.6%. Ninety-seven percent had acceptable transprosthetic mean pressure gradients (25 mmHg or less) 1 week after surgery. Follow-up was 100% complete and 76% of the patients were alive after a mean of 5 years. There was no structural valve failure or valve thrombosis. One patient required reoperation for perivalvular leak. Four patients had transient ischemic attacks and seven had strokes. These figures are, however, within the expected range for the age. CONCLUSION: Second generation pericardial valves perform well in elderly patients with small aortic roots. Postoperative hemodynamics are acceptable, valve durability of up to 8 years adequate, and the clinical results good, considering the age of the patients.

Minimal access aortic valve surgery.

OBJECTIVE: We report our experience with minimal access aortic valve surgery and discuss the three approaches used. METHODS: From June 1996 to October 1997, 18 patients underwent minimally invasive aortic valve surgery through three different incisions: right parasternal minithoracotomy (three cases), upper ministernotomy (11 cases), and transverse sternotomy (four cases). No special surgical instrumentation was used. Aortic valve replacement was carried out in 17 patients and aortic valve repair in one patient. The patients ranged in age from 42 to 86 years (mean 64 years). Concomitant procedures involving the aortic root and the ascending aorta were performed in five patients. RESULTS: There was no mortality and no complications related to the procedure or the access. There was no instability or paradoxical movement of the chest wall. One patient was reoperated for postoperative bleeding. All patients were discharged from hospital within the usual time. No attempts were made to discharge them earlier, even if they recovered quickly. CONCLUSIONS: Of the three incisions used, the upper ministernotomy seemed to be the safest and easiest to perform. Through this incision, both the aorta and the right atrium could be cannulated, the right ventricle was accessible, and concomitant procedures on the ascending aorta could be carried out. The drawback of minimal access aortic valve surgery in general is that it is difficult to de-air the heart and more difficult to master intra- and postoperative complications should they occur.

Periprosthetic leaks and valve dehiscence: alternative methods of repair.

BACKGROUND AND AIMS OF THE STUDY: Reoperations for periprosthetic leaks (PL) and valve dehiscence (VD) are associated with high mortality and substantial recurrence rate. Standard methods of repair are often not feasible due to friability of the annulus tissue or lack of space to locate the sutures. We have therefore used a variety of unconventional methods to close the leaks securely. CLINICAL MATERIAL AND METHODS: The clinical records of 25 patients reoperated for PL and VD between 1989 and 1995 were reviewed. Eighteen patients had aortic and seven mitral PL. Patients with mechanical heart valves were more frequently reoperated than those with bioprostheses (2.1% versus 0.7%). The PL was repaired in 16 cases, and the prosthesis was exchanged in nine cases with VD or large leaks. Six of the latter nine patients had active prosthetic endocarditis. A variety of surgical techniques was used to repair the leaks, including placing sutures from outside the aortic wall, through the atrial and ventricular septum, through the free left atrial wall and closure by single or double patch technique. RESULTS: Hospital mortality was 4% (1/25 patients) and one-year mortality 12.5%. None of the patients except one with active prosthetic endocarditis needed a second reoperation. CONCLUSIONS: If PLs are difficult to close with standard surgical technique, the alternative methods described might be useful. These methods can also be used during primary valve replacements where leaks remain.

Aortic valve replacement for aortic stenosis in patients with small aortic root.

BACKGROUND AND AIMS OF THE STUDY: Patients with aortic stenosis and small aortic ostia are getting more and more common in our practice. They now constitute a third of our aortic valve replacement (AVR) material. The patients are usually elderly women with small heart and body dimensions, sometimes making it difficult to implant sufficiently large valve prostheses. MATERIALS AND METHODS: We describe a non-selected series of 254 patients from a geographically defined area who underwent AVR during a six year period (1989-1995) and who were considered to have small aortic annulus, defined as patients receiving 19 and 21 mm prostheses. Mean age was 71 years, 42% were over the age of 75, 88% were women and 32% underwent concomitant coronary artery bypass grafting (CABG). Fifty-nine (23%) required pericardial patch enlargement of the aortic root to accommodate sufficiently large prostheses. Prostheses used included Björk-Shiley Monostrut (n = 54), CarboMedics (n = 58), St. Jude (n = 74), Sorin Bicarbon (n = 2), Mitroflow pericardial (n = 26) and Carpentier-Edwards pericardial valve (n = 40). Pericardial valves were usually employed in patients 75 years and older. RESULTS: Operative mortality was 3.1%. There was no mortality in patients undergoing isolated AVR. Late mortality, after a mean observation period of two years, was 4.9%. At Doppler echocardiography one week postoperatively, 95% had a gradient across the prosthesis that was considered to be within acceptable limits (resting mean gradient < 30 mmHg). In the remaining patients higher gradients indicated some degree of prosthesis-patient mismatch. CONCLUSIONS: To avoid this mismatch the surgical considerations include choosing a prosthesis with a large effective orifice area, using an optimal valve implantation technique (partly or completely supra-annular placement of the prosthesis) and, if this is not enough, enlarging the annulus with an outflow patch.

In vivo comparison of hemocompatibility of materials used in mechanical heart valves.

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.

An initial investigation into the wear and damage within the pivots of three types of bileaflet mechanical heart valves.

Two 29 mm St. Jude Medical valves, two 29 mm CarboMedics valves and two 29 mm Sorin Bicarbon valves were tested in a real time fatigue test rig. The test rig was run at 72 beats/min with a stroke volume of 70 ml for approximately one million cycles. Optical microscopy was used to investigate the valve surfaces. Possible deterioration of the surface finish was observed on the stops of the hinge recesses in the St. Jude Medical and CarboMedics valves. In the Sorin valves areas of the pyrolytic carbon coating was worn away adjacent to and on the valve stops.

Topical cooling of the heart. A valuable adjunct to cold cardioplegia.

Topical (local) cooling of the heart is a valuable adjunct to cold cardioplegia, particularly to crystalloid cardioplegia and to cardioplegia in patients with long aortic cross-clamping times. The topical cooling not only enhances myocardial hypothermia but also prevents the heart from being rewarmed by coronary collaterals and by heat transmission from surrounding organs during the period of aortic cross-clamping. If ice slush is used for topical cooling, a cardiac insulating pad should be used to isolate the heart and to protect the left phrenic nerve from cold injury. To illustrate the use of the insulating pad and to demonstrate the efficiency of topical cooling during open-heart surgery, a series of temperature measurements were made.

An in vitro study of prosthetic heart valve sound.

Patients with an implanted mechanical heart valve sometimes experience the closing sounds of the valve as disturbing. To study the generation of valve sounds in general, a pulse duplicator study was carried out, testing eight commonly used types of prosthetic valves in the aortic position. Pulse rate was set at 70 beats/min, stroke volume at 70 ml and mean 'aortic' pressure at 100 mmHg. Despite the controlled conditions, there was great variability of the closing sound, in both intensity and spectral composition, making noise comparisons and spectral characterization ('sonoprint') difficult. In general, bileaflet mechanical valves produced less noise than did tilting disc valves, particularly those with large opening angles. One small-size (23 mm) tilting disc valve produced 50% less noise than large types. The plastic ball valve, the porcine and the polyurethane trileaflet valve all were very quiet.

Perception of mechanical heart valve sounds.

Most currently used mechanical heart valve prostheses generate a distinct sound when they close. This sound is sometimes disturbing to the patient, and may impair quality of life. In a study of 285 patients followed up for a mean of 2.5 years after mechanical heart valve replacement, one-third were sometimes disturbed by sounds emanating from the prosthesis. Older patients were less disturbed than young ones, but whether this could be explained by age-related impairment of hearing ability (presbyacusis) was not possible to determine. Prosthetic size, implantation site, patient's weight, body surface area and type of prosthesis did not statistically differ according to experience of prosthetic sounds. Although few patients were seriously disturbed by these sounds, it is hoped that mechanical heart valves of the future will function more quietly.

Heart valve replacement with the Björk-Shiley Monostrut valve: early results of a multicenter clinical investigation.

To evaluate the clinical performance of the Björk-Shiley Monostrut prosthesis, five centers combined their early experience. Between May, 1982, and June, 1985, 537 prostheses were implanted in 486 patients at these centers: 246 patients had aortic valve replacement (AVR), 163 underwent mitral valve replacement (MVR), and 47 had double-valve replacement (DVR). Thirty patients underwent other, more complex procedures. Concomitant cardiac procedures were performed in altogether 25%. Overall hospital (30 days) mortality was 5.1% (3.6% for AVR, 4.3% for MVR, 8.3% for DVR, and 16.6% for other procedures). The patients were followed up at 6- to 9-month intervals from 6 to 48 months (mean follow-up, 33 months). Follow-up was 99.6% complete. Late mortality was 7.2%. The three-year survival rate was 91.0% for AVR, 92.3% for MVR, and 76.2% for DVR. There was no structural failure of the prosthesis. No instances of valve thrombosis and fatal thromboembolism occurred in anticoagulated patients. The three-year incidence of freedom from thromboembolic events (including TIA) was 89.8% for AVR, 94.9% for MVR, and 90.2% for DVR. Preoperative and postoperative data for the assessment of mechanical hemolysis was available in 60% of the patients. The degree of mechanical hemolysis was low and did not change with time. Although the follow-up is still short, the Björk-Shiley Monostrut prosthesis appears to represent an improvement over previous Björk-Shiley models, particularly with regard to durability.

Cineradiographic functional evaluation of the Björk-Shiley monostrut prosthesis. A follow-up study of 46 consecutive patients.

In 46 patients, 51 Björk-Shiley monostrut valves were studied with high-speed cineradiography 9 months after implantation. Each valve was viewed in lateral, frontal and oblique projections for 10-12 heart beats. In the aortic valves the opening time was 0.04-0.067 (mean 0.052) and closing time 0.04-0.067 (mean 0.046) sec. In all these valves the maximum opening angle was 70 degrees. Disc rotation could be monitored in 29/31 valves, and during 10 heart beats averaged 20 degrees. Disc slide of 2.0-2.5 mm was seen in 27/31 valves. It occurred during the last 40-50 degrees of opening and the first 20-40 degrees of closing. In mitral valves with sinus rhythm (12/20), the opening time was 0.053-0.106 (mean 0.073) and closing time 0.040-0.106 (mean 0.061) sec. Mean disc rotation (recorded in 17/20 valves) during 10 heart beats was 25 degrees, and disc slide of 2.0-2.5 mm was found in all but one case, mainly during the last 50 degrees of opening and the first 30 degrees of closing. The valve opened to 70 degrees in all but one patient, in whom the disc clearly impinged against the left ventricular wall and opened only to 35-50 degrees at rest. At reexamination a year later the patient was asymptomatic, in sinus rhythm, and the disc had regained full movement with 70 degrees opening.

Optimal insertion technique for the Björk-Shiley valve in the narrow aortic ostium.

The Björk-Shiley tilting disc valve was used for aortic valve replacement (AVR) in 250 consecutive patients between 1977 and 1982. One hundred and ninety-six patients had isolated AVR, and 54 had combined procedures (double- or triple-valve replacement in 31, associated coronary artery bypass grafting in 20, and miscellaneous procedures in 3). A special technique for inserting large Björk-Shiley valves without using outflow patches or annuloplastic procedures was developed. This method included allowing the right portion of the aortic incision to end about 0.5 cm above the noncoronary sinus; the use of simple interrupted sutures; placement of the prosthetic sewing ring on top of the annulus of the noncoronary sinus, thereby tilting the valve slightly in the outflow tract; and routine orientation of the major opening of the valve toward the annulus of the noncoronary sinus. This orientation resulted in the largest effective orifice area at postoperative catheterization. None of the male patients received a valve smaller than 23 mm, and none of the female patients were given a valve smaller than 21 mm. The convexoconcave model of the Björk-Shiley valve was used in 71% of the patients. An outflow patch was required only in 1 patient with concomitant supravalvular stenosis of the aorta. The combination of adequate myocardial protection, comparatively short aortic cross-clamping times, and the use of large, properly oriented Björk-Shiley valves resulted in satisfactory postoperative hemodynamics in all patients. In fact, none of the 196 patients undergoing isolated AVR and only 5 (9%) of the 54 patients undergoing combined procedures required postoperative inotropic stimulation. There were no operative deaths, and all patients left the hospital in good condition. The Björk-Shiley tilting disc valve is a reliable and well-functioning aortic valve substitute that is particularly suited for patients with narrow aortic ostia. With attention to certain details in the insertion technique, encouraging clinical results can be obtained with this prosthesis.

Detachment of the septal tricuspid leaflet during transatrial closure of isolated ventricular septal defect.

In 27 (18%) of the 151 patients who underwent transatrial closure of isolated ventricular septal defect (VSD) between 1966 and 1979, the tricuspid valve was partially detached in order to achieve better exposure. All 27 patients had defects of the membranous or paramembranous type situated behind the tricuspid septal cases, tight chordae tendineae crossed over the defect and inserted in the edge of the VSD. A 15 to 20 mm incision in the septal leaflet was usually needed to expose the defect sufficiently. There were two operative deaths among the 27 patients, both unrelated to the tricuspid incision. The remaining patients had uncomplicated postoperative courses. There were no long-term complications or instances of significant tricuspid valve incompetence, major residual shunt, or heart block at follow-up. Three patients, operated upon at the ages of 3, 3, and 6 years, respectively, had residual pulmonary hypertension. In one patient, who died 4 years postoperatively in a traffic accident, the tricuspid valve was intact and the previous incision could hardly be seen. It is concluded that detachment of the septal tricuspid leaflet is a safe procedure during transatrial closure of a VSD.

Right atrial-right ventricular anastomosis for correction of tricuspid atresia.

Previously reported methods for the correction of tricuspid atresia involve the use of conduits and/or valves. Since many of the younger patients will outgrow their conduits and the long-term durability of the valve prostheses is open to question, we have devised an operation in which the right atrial (RA) appendage is anastomosed to the right ventricle (RV) with the aid of a pericardial patch. The RV, if not too hypoplastic, is used as a pumping chamber and the pulmonary valve is in its normal position. Three patients, 8, 9, and 12 years of age, were operated on with good clinical and hemodynamic results. Postoperatively, all three were acyanotic and had improved physical capacity compared with their preoperative status. The RA pressure in the first two patients 1 year after operation was 12 mm. Hg and at angiocardiography the RA-RV anastomosis was widely patent. In one of the patients, the RV was too hypoplastic to function. It should be possible to perform this operation even in younger patients and it may eliminate the need for palliative procedures and reoperations.

Pulmonary atresia: surgical considerations and results in 103 patients undergoing definitive repair.

Surgical considerations and results of repair of 103 patients with pulmonary atresia are reviewed. The operative mortality was 10%, related primarily to inability to relieve right ventricular hypertension and to low cardiac output after complex repairs involving significant associated anomalies. In a follow-up study ranging from 6 months to 8 years, there were four late deaths, each being a result of persistent right ventricular hypertension. All but one of the surviving patients are in Class I or Class II. Since operative and late mortality and morbidity are related to unrelieved right ventricular hypertension due to restricted pulmonary arterial outflow, it should be possible to improve results by performance of a preliminary systemic-pulmonary arterial shunt for patients with hypoplastic pulmonary arteries and by correction of patients with large systemic-pulmonary arterial shunts before the development of pulmonary vascular obstructive disease. The striking relief of cyanosis, exercise intolerance, and other symptoms, and the generally favorable operative risk, justify the continued application of surgical correction of pulmonary atresia.