Hemodynamic evaluation of the Carbomedics R, St Jude Medical HP and Sorin-Bicarbon valve in patients with small aortic annulus

Comparative Long-Term Clinical Performance of Mechanical Aortic Valve Prostheses

Importance

Aggregated data and long-term follow-up in national health data registers offer the opportunity to compare the performance of mechanical aortic prostheses within the same population.

Objective

To investigate the clinical performance of mechanical aortic valve prostheses.

Design, Setting, and Participants

This nationwide cohort study included all 5224 patients who underwent primary mechanical aortic valve replacement in Sweden between January 1, 2003, and December 31, 2018. Statistical analysis was performed between May and September 2023.

Exposures

Surgical aortic valve replacement with the On-X, Carbomedics, Bicarbon, Standard, Regent, Open Pivot, Masters, or Advantage valve models.

Main Outcomes and Measures

The primary outcome was all-cause mortality, and secondary outcomes were reintervention, heart failure, major bleeding, stroke, and embolic events. Regression standardization was used to account for baseline differences.

Results

Overall, 5224 patients (mean [SD] age, 56.8 [11.7] years; 3908 men [74.8%]) were included. Total follow-up time was 43 982 person-years (mean [SD], 8.4 [4.6] years; maximum, 17.2 years). After regression standardization, there was a significant difference in 10-year mortality between the Carbomedics model group (17%; 95% CI, 15%-18%), Regent model group (17%; 95% CI, 13%-20%), and Standard model group (17%; 95% CI, 14%-19%) compared with the Bicarbon model group (27%; 95% CI, 21%-34%).

Conclusions and Relevance

In this cohort study of mechanical valve surgical aortic replacement outcomes in Sweden, the rate of all-cause mortality was higher in the Bicarbon group than in the Carbomedics, Regent, and Standard model groups. These findings warrant further research on the long-term clinical performance of the Bicarbon valve.

Does the St. Jude Regent 17-mm Offer Better Outcomes Than the Hemodynamic Plus 17-mm Aortic Valve Mechanical Prothesis?

OBJECTIVE

The aim of the present study is to report the early and mid-term clinical and hemodynamic results of a prospective trial investigating the clinical performance of the St. Jude Medical Regent 17 mm (SJMR-17) versus St. Jude Medical Hemodynamic Plus 17 mm (SJMHP-17).

MATERIALS AND METHODS

Between January 2000 and August 2013, 20 patients (Group I) with aortic valve (AV) stenosis underwent first time AV replacement with a SJMR-17 and nine patients (Group II) underwent AV replacement with a SJMHP-17. The mean follow-up was 58 ± 31 months.

RESULTS

There was one death in Group I. The end-diastolic IVS thickness and end-systolic posterior left ventricle (LV) wall thickness was reduced significantly in boths groups (p = 0.001 and p = 0.006 in Group I and p = 0.007 and p = 0.011 in Group II). The peak and mean transprosthesis gradients (P-TPG and M-TPG) were 29 ± 6.8 mmHg and 17.5 ± 4.5 mmHg in Group I, significantly lower than in Group II (55.2 ± 19.7 mmHg and 28.8 ± 7.7 mmHg). The postoperative left ventricular mass (LVM) and indexed left ventricular mass (LVMi) were reduced significantly in both groups versus the preoperative values. The postoperative LVMi was 114.5 ± 10.6 g/m(2) in Group I versus 127 ± 8 g/m(2) in Group II (p = 0.01). With dobutamine, heart rate, left ventricular ejection fraction, cardiac output, transprosthesis peak, and mean gradients increased significantly in both groups, however, the P-TPG and M-TPG were significantly higher in Group II (p = 0.026 and p = 0.022) despite a non-significant increase of the indexed effective orifice area.

CONCLUSIONS

The SJMR-17 can be employed with satisfactory postoperative clinical and hemodynamic outcomes in patients with small aortic annulus, especially in elderly patients offering better outcome than SJMHP-17.

Diagnostic evaluation of left-sided prosthetic heart valve dysfunction

Prosthetic heart valve (PHV) dysfunction is a rare, but potentially life-threatening, complication. In clinical practice, PHV dysfunction poses a diagnostic dilemma. Echocardiography and fluoroscopy are the imaging techniques of choice and are routinely used in daily practice. However, these techniques sometimes fail to determine the specific cause of PHV dysfunction, which is crucial to the selection of the appropriate treatment strategy. Multidetector-row CT (MDCT) can be of additional value in diagnosing the specific cause of PHV dysfunction and provides valuable complimentary information for surgical planning in case of reoperation. Cardiac magnetic resonance imaging (CMR) has limited value in the evaluation of biological PHV dysfunction. In this Review, we discuss the use of established imaging modalities for the detection of left-sided mechanical and biological PHV dysfunction and discuss the complementary role of MDCT in this context.

A novel multi-planed mechanical aortic valve for increasing the effective orifice area

BACKGROUND

Today, there is still confusion about mismatch of the orifice area of the mechanical valve and body surface area of the patient in aortic valve surgery. Creating a larger effective orifice area is the aim with this new valve design.

METHOD

This valve is multi-planed, one housing is seated at the aortic annulus for the coronary orifices to receive blood in diastole, the other housing or housings are seated to the ascending aorta obliquely to increase the orifice area of the valve. The ascending aorta can be enlarged if necessary.

RESULT

Valves with orifice areas larger than 6 cm(2) can be achieved with multi-planed aortic valves.

DISCUSSION

The use of this valve depends on the fact that the aorta is a living tissue and can grow over time to normal values.

Experimental study of a multiplaned mechanical aortic valve using bovine aorta

A newly designed multiplaned mechanical aortic valve was created in which there would be an angle between the stents so the valve would have a greater orifice area. This study was performed to test this valve on bovine aorta to determine whether or not there would be a pressure gradient on both sides of the valve. The valve created is multiplaned with one stent thought to be seated on the aortic annulus for the coronary orifices to receive blood in diastole, whereas the other stent is thought to be seated on the ascending aorta obliquely to increase the orifice area of the valve. The ascending aorta could be enlarged if necessary. A multiplaned valve resembling the valve which has two planes was tested on a Dacron tube, one side of which was formed with a bovine aorta. Pressure readings before and after the bovine aorta was thinned were taken when a 17 L/min flow through the tube was maintained. A 65 mmHg mean pressure gradient and a zero pressure gradient were produced before and after thinning the bovine aorta. The multiplaned mechanical aortic valve produces no gradient if the aorta is elastic. This valve can solve the gradient problem in aortic valve surgery because the aorta is a living and elastic tissue.

Left ventricular mass index reduction early after an isolated aortic valve replacement with St. Jude Medical 19A-HP

OBJECTIVES

It has been reported that the left ventricular mass index (LVMI) for the hypertrophic myocardium is reduced at an early stage following surgery. In this study, those factors affecting the changes in early postoperative LVMI were investigated in cases in which a St. Jude Medical 19A-HP (19HP) mechanical heart valve was used.

METHODS

We studied 16 consecutive patients with pure aortic stenosis undergoing isolated aortic valve replacement using a 19HP between January 1994 and July 2001. The patients were all female, aged 64 +/- 6 years, with a body surface area of 1.44 +/- 0.10 m2 and preoperative New York Heart Association (NYHA) classification of 2.2 +/- 0.5. All patients underwent transthoracic echocardiography at 4.2 +/- 3.3 days before and 16.3 +/- 10.2 days after operation, and cardiac catheterization within a mean period of one month before operation. The correlations between the decrease of LVMI at 16.3 +/- 10.2 days after operation and perioperative parameters were determined.

RESULTS

There was significant LVMI regression postoperatively (15 +/- 12%, p = 0.01), and only a significant negative correlation between the decrease of LVMI and preoperative left ventricular pressure (LVp) [r = -0.74, p < 0.01]. There was no effective LVMI reduction in the high preoperative LVp group (> or = 210 mmHg).

CONCLUSION

It is expected that in the high LVp group, huge wall stress was being applied to the left ventricular muscle immediately before surgery and in the early period after surgery. Preoperative LVp is an important index for determining the surgical timing and safe perioperative management. We recommend early surgical treatment before LVp becomes more than 210 mmHg.

Nominal size in six bileaflet mechanical aortic valves: a comparison of orifice size and biologic equivalence

OBJECTIVES

Nominal size remains the standard by which valves are compared, but its relationship with orifice area and the patient tissue annulus diameter may differ according to valve design. The aims of this study were to measure the orifice size and compare biologic equivalence in six bileaflet mechanical heart valve designs.

METHODS

The inflow aspect of each of 29 valves was photographed then digitized, and the maximum internal diameter and orifice area were calculated. Biologic equivalence was assessed with a series of machined polypropylene blocks.

RESULTS

The orifice area ranged between 159 and 222 mm(2) for the six size 19 valves. The internal diameter ranged from 1.6 to 4.6 mm less than the manufacturer's nominal size. Biologic equivalence assessed from an estimate of tissue annulus diameter with machined blocks ranged from 1.0 and 3.5 mm larger than nominal size for the intra-annular valves. This diameter ranged from 3.5 mm smaller to 1.5 mm larger than nominal size for the supra-annular valves.

CONCLUSION

There are major differences between nominal size and biologic equivalence. This may lead to confusion when attempting to make comparisons between different valve designs with the same nominal size. A clearer sizing nomenclature is required and could be based on in vitro assessment of tissue annulus diameter or an alphanumeric code.

Standard 19mm St Jude aortic valves in patients with body surface less than 1.7m2

Although new models of bileaflet valves with improved orifice have been devised, aortic valve replacement with 19mm prostheses still raises concerns about long term effects of residual transprosthetic gradient.

We reviewed our experience with 19 mm standard model St Jude prostheses in 68 patients operated on between January 1983 and December 1995. Clinical late assessment was performed to evaluate the incidence of valve related complications. Postoperative echocardiography was performed to evaluate hemodynamic performance of the prostheses.

Mean body surface area was 1.66±0.14m2. Late postoperative peak gradient was 53.85±7.16 mmHg; mean gradient was 34.80±5.55 mm Hg; effective orifice area was 1.93±0.05 cm2. Thirteen-year actuarial survival has been 90.89 ± 0.6%; thirteen-year freedom from embolism 89.41 ± 0.7% and freedom from hemorrhage 98.25 ± 0.02%. No case of prosthetic endocarditis, thrombosis, or reoperation was observed during follow-up.

Standard versus hemodynamic plus 19-mm St Jude Medical aortic valves

OBJECTIVE

We reviewed our experience with aortic valve replacement using 19-mm St Jude Medical prostheses (St Jude Medical, Inc, St Paul, Minn) in 119 patients, among which 68 (group A) had a Standard model and 51 (group B) had a Hemodynamic Plus model.

METHODS

Comparison between the 2 models included analysis of early and late mortality and all valve-related complications. Postoperative echocardiography was performed to evaluate the hemodynamic performance of both prosthetic models. Laboratory tests were performed to evaluate the amount of red blood cell damage caused by the transprosthetic turbulent flow.

RESULTS

Average body surface area was 1.66 +/- 0.14 m(2) in group A and 1.65 +/- 0.16 m(2) in group B (P =.72). There was no statistically significant difference between the 2 groups in terms of preoperative variables (sex, cardiac rhythm, body surface area, preoperative gradients, and New York Heart Association class). Five-year follow-up was 100% complete. Although group A patients had significantly higher postoperative peak and mean gradients (P =.0001) and a lower effective orifice area (P =.0001), no statistical differences were found in terms of late (5-year) survival (P =.6) and postoperative complications (P =.09). Moreover, postoperative left ventricular mass was found to be similar in the 2 groups (P =.18). Hematologic evaluation did not show any significant difference between the 2 groups as to incidence of hemolysis.

CONCLUSIONS

Aortic valve replacement with 19-mm aortic prostheses in patients with a body surface area of less than 1.7 m(2) allows good results. Although Hemodynamic Plus models have better hemodynamic results, no significant difference was found in terms of clinical results and clinical hemolysis.

A novel comparison of stentless versus stented valves in the small aortic root

BACKGROUND

Previous studies have compared prosthetic valves on the basis of industry-labeled valve sizes. Unfortunately, the relationship between the labeled size and the true measured external or internal diameter differs between valve manufacturers. Therefore hemodynamic comparisons between prosthetic valves are inaccurate if based solely on industry-labeled valve sizes.

METHODS

We have previously demonstrated that the internal diameter of a 21-mm Carpentier-Edwards pericardial stented valve is similar to that of a 25-mm Toronto stentless porcine valve. Therefore we chose to compare postoperative hemodynamics in patients who received 19-, 21-, or 23-mm Carpentier-Edwards pericardial stented valves (inner diameter 18-22 mm, n = 69) with those in patients who received 23- or 25-mm stentless porcine valves (internal diameter 19-21 mm, n = 41).

RESULTS

Patients in the Carpentier-Edwards group were more likely to be elderly and more likely to require concomitant revascularization. Operative mortality was lower in the stentless porcine valve group (0% vs 9%, P =.06). Hospital stay and ventilation requirements were shorter in the stentless porcine valve group. Postoperative hemodynamics were similar in the two groups.

CONCLUSIONS

These data provide evidence that stentless and stented valves have similar hemodynamic profiles in the small aortic root when matched on true measured internal diameters. The clinical benefit of the stentless porcine valve may be due to patient selection or the lack of a rigid stent in the small aortic root, but it is not due to hemodynamic superiority over stented aortic valves of similar sizes.