TTK Chitra tilting disc valve: Hemodynamic evaluation

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1 IJTCVS Pawan et al 117 Original Article TTK Chitra tilting disc valve: Hemodynamic evaluation Pawan Kumar*, M.Ch, Bharat Dalvi**, DM, Raghvendra Chikkatur*, MS, Pranav Kandhachar*, MS, Rajesh Parida*, MS, Vinod Ahuja*, MS, Uday Eknath Jadhav*, M.Ch, DNB, Anil Tendolkar*, MS Dept. of Cardiovascular & Thoracic Surgery, LTMMC & LTMGH, Sion, Mumbai* Consultant Cardiologist, Mumbai** Abstract Background and aim of study: The TTK Chitra mechanical heart valve is being widely used in India. We present a hemodynamic study of this valve implanted in the mitral and aortic positions. Methods: 547 patients had 654 valves implanted in the aortic and/or mitral positions. 230 patients underwent an echocardiography examination with Doppler evaluation, for estimating the effective orifice area and transvalvular gradients. Results: In the mitral position, for valve sizes 25, 27 and 29 mm, the mean gradients (in mm Hg) are 5±3, 4±2 and 4±2, and the Effective orifice areas (in cm 2 ) are 2.8±0.8, 3.1±0.7 and 2.9±0.7 respectively. In the aortic position, for valve sizes 21 and 23 mm, the gradients (in mm Hg) are 10±5 and 9±4, and the Effective orifice areas (in cm 2 ) are 1.5±0.5 and 1.8±0.3 respectively. Conclusions: The TTK Chitra valve is hemodynamically comparable to other mechanical valves. (Ind J Thorac Cardiovasc Surg, 2004; 20: ) Key words: Hemodynamics, Mechanical heart valve, Echocardiography, Heart valves Introduction The development of the TTK Chitra valve was initiated in late 1970 s at the Sree Chitra Tirunal Institute for medical sciences and technology, Thiruvanathpuram, India. After trials, the valve became available since February 1995 for clinical use, as the TTK Chitra heart valve. It has an Ultra high molecular weight polyethylene disc, Haynes-25 alloy (Haynes International Inc., USA) cage and polyester suture ring. It is manufactures by TTK Healthcare limited (based at Bangalore). So far, various clinical studies have been reported 1,2,3,4 but hemodynamic studies are far and few. We present our experience with the TTK Chitra valve in mitral and aortic positions and also an in-vivo hemodynamic assessment of the valve. Material & Methods Between February 1999 and July 2002, 547 patients had Address for correspondence: Dr. Pawan Kumar, Lecturer, Dept. Of Cardiovascular & Thoracic Surgery, LTMMC & LTM General Hospital, Sion, Mumbai , India E mail /023 Received - 09/02/04; Review Completed - 19/04/04; Accepted - 14/07/ TTK Chitra valves implanted in the aortic and/ or mitral positions. All the patients referred to our department for valve replacement surgery were primarily scheduled for valve replacement with a TTK Chitra valve. This was irrespective of the underlying valve pathology, the clinical status of the patient or a previous operation. In a multivalvular operation, if a patient received even one TTK Chitra valve, the patient was included in the study irrespective of the type of the other valve used. Patients who have undergone other associated procedures were also included in the study. During the study, TTK Chitra valve, in aortic position, was available in sizes 21 mm and 23 mm only. Hence, patients requiring other sized aortic valves did not receive TTK Chitra valves. Since the past 1 year, 19, 25 and 27 mm TTK Chitra valve sizes, for aortic position, are also available. Our policy is to use only biological valves for tricuspid valve replacement (TVR). We believe that the incidence of prosthetic valve thrombosis is high in the tricuspid position. 547 consecutive patients, consisting of 310 males and 237 females received 634 implants with the TTK Chitra in mitral and/ or aortic positions. Their age ranged from 9 years to 64 years (mean age = 26±5 years). Pre-Operatively, all the patients were evaluated by a detailed clinical examination, electrocardiogram (ECG), 117

2 118 Pawan et al IJTCVS Chitra valve 2004; 20: chest X-ray and a 2 Dimensional Echo with color Doppler examination. All the patients who were more than 50 years age with history of tobacco abuse and/ or pain in chest, diabetes or had ECG evidence of ischemia were subjected for coronary angiography. 19 patients underwent coronary angiograms of which 4 had significant coronary artery disease. 238 were in NYHA class II, 235 in class III and 74 were in class IV. On admission 233 had sinus rhythm while 314 were in atrial fibrillation. 80 patients had undergone previous operations if form of a closed mitral commissurotomy (64 patients), open mitral valvotomy (6 patients), Mitral Valve Replacement with biological valve (8 patients) and Aortic Valve Replacement with biological valve (2 patients). Associated pathologies, requiring surgical procedure were, atrial septal defect in 20, significant tricuspid valve disease in 47 and coronary artery disease in 4 patients. Tricuspid valve disease was considered significant if there was any element of tricuspid stenosis or if the tricuspid regurgitation was equal to or more than moderate (in the absence of severe pulmonary hypertension or if associated with pulsatile hepatomegaly and/ or peripheral edema.) On admission patient s hemogram, coagulation profile, renal functions, and liver functions were studied. Patients were continued on digoxin till the day of surgery, until unless the patient had digoxin toxicity. If the patients were on aspirin and/or warfarin, it was omitted atleast 7 days prior to the surgery. All were operated using conventional cardiopulmonary bypass through a median sternotomy at moderate hypothermia, using membrane oxygenator, antegrade intermittent cold blood cardioplegia. Mitral valve replacement was performed through a longitudinal paraseptal incision except in patients with atrial septal defect. In the later a transseptal approach was used. Posterior mitral leaflet was preserved, if possible, only in patients with isolated mitral regurgitation. In patients with isolated mitral stenosis, due to the absence of annular dilatation, a small size prosthesis would have to be implanted if the posterior mitral leaflet was preserved. In those, in whom the posterior mitral leaflet was preserved, the major orifice of TTK Chitra valve was always oriented towards the anterior annulus. Aortic valve replacement was performed through a transverse or an oblique aortotomy. The major orifice of the valve was always directed towards the greater curvature of the aorta. All patients underwent valve replacement using three 2-0 polypropylene (Prolene, Ethicon Inc) continuous sutures except for those who had annular calcification, infective endocarditis or had undergone a previous biological valve replacement. The later mentioned group of patients does not have a tough fibrotic annulus and hence, we believe, can cause the suture to cut-through. This would be catastrophic if the suture line was continuous. In these patients, 2-0 Ethibond (Ethicon division, Johnson & Johnson), non-pledgetted, interrupted sutures were used. Mitral valve replacement was performed in 348 patients, Aortic valve replacement in 92 patients and a combined mitral and aortic valve replacement in 107 patients. The underlying valvular pathologies are shown in Table 1. The valve sizes implanted in the mitral and aortic positions are mentioned in Tables 2 and 3 respectively. Associated procedures performed included open mitral commissurotomy in 36, closure of atrial septal defect in 20, tricuspid valvotomy and/ or plasty in 34, tricuspid valve replacement in 8 and a coronary bypass grafting in 4. Anti coagulation regime was started on the 1 st postoperative day with oral 5 mg Warfarin sodium. An International Normalized Ratio (INR) was maintained between 2.5 to 3 for aortic valve replacement and between 3 and 3.5 for Mitral valve or double valve replacement. At the time of discharge the patients were explained in detail about the anticoagulation regimen Table 1. Mitral and aortic valve pathology Pathology Mitral stenosis (MS) 158 Mitral regurgitation (MR) 136 MS + MR 161 Aortic stenosis (AS) 82 Aortic regurgitation (AR) 52 AS + AR 65 Table 2. Chitra Valve sizes implanted in the mitral position. Valve size (in mm) Table 3. Chitra Valve sizes implanted in the aortic position. Valve size (in mm)

3 IJTCVS Pawan et al 119 and the complications associated with low/high international normalized ratio. Patients were advised to follow up once in 2 weeks for the first month and then every 1-monthly for repeated INR check. During every follow up visit, patients were evaluated clinically and the INR checked. A chest X-ray, electrocardiogram and a 2D-Echo with color Doppler was done atleast once between 3 months to 1 year, postoperatively. Echo with Doppler was done using Hewlett-Packard Sonos 5500 echocardiography machine. Mitral valve prosthesis was evaluated in the apical four-chamber view, and the aortic valve prosthesis in apical fivechamber view. The peak velocity, mean gradient and effective orifice area of the prosthetic valve was evaluated in both mitral and aortic positions. A total of 230 patients underwent echocardiographic examination at 3-month follow-up. The Epistat package was used for statistical analysis. Results There were a total of 7 early (within 30 days) deaths (1.25 %). Of these 4 (1.4 %), 1 (1.1%) and 1 (0.99%) patients had undergone mitral valve replacements, aortic valve replacements and double valve replacement respectively. 15 (2.6%) patients required re-exploration for bleeding. 15 (2.6%) had superficial wound infection and 3 (0.6%) had deep wound infection. Complete heart block was seen in 2 (0.4%) patients. A total 502 of 540 (93%) patients were followed up for a period ranging from 120 to 990 days (mean = days), either through a structured questionnaire or at the out patient department of this hospital. Table 4 shows the incidence of thromboembolism, infective endocarditis, valve thrombosis and hemorrhage of patients. The linearized rates for thromboembolic episodes, overall, were 3.8%/y for mitral valve replacement, 2.1%/y for aortic valve replacement and 3.7%/y for double valve replacement. The linearized rates for infective endocarditis were Table 4. Incidence of valve related complications during follow-up TOTAL MVR AVR DVR TEE 20 (4%) 14 (4.3%) 02 (2.4%) 04 (4.2%) IE 03 (0.6%) 02 (0.6%) 0 01 (1%) Thrombosis 05 (1%) 03 (0.9%) 0 02 (2%) Hemorrhage 07 (1.4%) 04 (1.2%) 02 (2.4%) 01 (2%) SVD TEE- Thromboembolic episode, IE- Infective endocarditis, SVD- Structural valve deterioration 0.5%/y for mitral valve replacement, nil for aortic valve replacement and 0.9%/y for double valve replacement. The linearized rates for valve thrombosis were 0.9%/y for mitral valve replacement, nil for aortic valve replacement and 1.75%/y for double valve replacement. The linearized rates for major hemorrhage were 1%/y for mitral valve replacement, 2.1%/y for aortic valve replacement and 1.75%/y for double valve replacement. There were no structural valve damages in any group. Postoperatively, 391 (77.9 %) patients were in New York Heart association class I, 80 (15.9 %) were in class II and 31 (6.2 %) were in class III. There was one late death. All the patients (n=230) who visited the out patient department underwent an echocardiographic evaluation. The results of the echocardiographic evaluation are described in Tables 5 and 6. Table 5. Trans valvular gradients, Peak velocity and effective orifice area of Chitra valve in Mitral position. Valve size Mean Peak Velocity Effective (in mm) Gradient (in m/ sec) orifice area 25 5±3 1.8± ± ±2 1.7± ± ±2 1.7± ±0.7 Table 6. Trans valvular gradients, Peak velocity and effective orifice area of Chitra valve in Aortic position. Valve size Mean Peak Velocity Effective (in mm) Gradient (in m/ sec) orifice area 21 10±5 2.9± ± ±4 2.6± ±0.3 Discussion The most important variables that measure prosthetic valve performance are mechanical integrity, hemodynamic characteristics and thrombogenecity. Other adverse events that occur after valve replacement are prosthesis related and are classified by reporting guidelines 5. It has been shown that thromboembolic rates vary considerable among different series of same prosthesis 6 because of various probable factors, viz., differences in patient population, method of data collection and management of anticoagulation. The incidence of thromboembolism was marginally higher in the double valve position, in comparison to other series 4,6,7, although various above-mentioned factors may contribute. The incidence of infective endocarditis, valve 119

4 120 Pawan et al IJTCVS Chitra valve 2004; 20: thrombosis and hemorrhage is similar to those reported for other mechanical valves 4,6,7.8. However it should be remembered that the follow-up is of a short term. It would have been ideal to have all the surviving patient s echoed so as to take away any bias. However, due to poor socio-economic condition of our patients, many could not travel to our center within the stipulated period of the study. However the clinical profile of the patients (n=230) who underwent echocardiography was statistically indistinguishable from the patients (n=501) totally followed up; with respect to mean age, functional class status, left ventricular ejection fraction and cardiac rhythm. Doppler Echocardiography plays an important role in assessing prosthetic valve function. Doppler recordings are similar to that of native valve studies, except that the velocities are higher because all prosthetic valves are mildly stenotic 9. In our study a Hewlett Packard Sonos 5500 echocardiography machine was used and the same cardiologist performed all the examinations. Movements of the occluder and the sewing ring were evaluated. None of the patients in our series had impaired movement of the occluder or rocking motion of the sewing ring. Doppler echocardiography allows accurate evaluation of trans-valvular flow patterns, thus facilitating recognition of turbulent, stenotic and regurgitant signals. Peak transvalvular velocities can be readily estimated. Failure to align the ultrasonic beam results in significant underestimation of transprosthetic velocity. To obtain exact velocity across the TTK Chitra valve the following technique was followed. The continuous wave cursor was arbitrarily placed parallel to the assumed direction of the flow. The transducer was then carefully maneuvered until well-defined velocity waveforms with the highest velocities were obtained and then a parallel orientation was assumed. The peak velocities so estimated across the TTK Chitra valve are shown in Table 5 and 6. The peak instantaneous gradients have no suitable counterpart at catheterization, but the mean pressure gradients computed by both catheterization and Doppler techniques are conceptually similar and are therefore more reliable methods for quantifying transprosthetic obstruction 10. Hence mean gradients were recorded across TTK Chitra valve in both mitral and aortic positions. Apical four-chamber view was used for parallel alignment of continuous wave cursor with the transmitral flow, and apical five-chamber view for attaining parallel orientation with the transaortic prosthetic flow signals. Soo CS 11, Phadnis 12, Reisner 13, Vongpatasin 14, have done echocardiographic evaluation of various prosthetic valves and have shown the probable gradients, to be considered normal for that prosthesis, across them. The gradients calculated across the TTK Chitra valve have been shown in Tables 5 and 6. The mean diastolic gradient across the TTK Chitra valve (27 mm) in mitral position was 4±2 mm of Hg, which was comparable to other mechanical valves (Table 7). The gradients across the TTK Chitra valve in the mitral position are comparable to gradients shown (across TTK Chitra valve) by Nagarajan et al 15. Nagarajan et al reported mean gradients of 5.09±2.14 mm of Hg in the mitral position and 14.37±5.07 mm of Hg in the aortic position. In our study, the mean systolic gradient across the TTK Chitra valve (21 mm) in aortic position was 10±5 mm of Hg, which is also comparable to gradients across other mechanical valves (Table 8). Table 7. Comparison of peak velocity, mean gradients, and effective orifice area in mitral position Valve Peak Velocity Mean Effective (27 mm) (m/sec) Gradient orifice area Chitra 1.7±0.2 4±2 3.1±0.7 St. Jude 1.6±0.3 5±2 2.7±0.8 Starr-edward 1.8±0.4 5±2 2.1±0.5 Medtronic-hall 1.7±0.3 3±1 2.9±0.9 Table 8. Comparison of peak velocity and mean gradients in aortic position Valve Peak velocity Mean Gradient (21 mm) (in m/ sec) (in mm of Hg) Chitra Valve 2.9±0.6 10±5 Starr-edward 3.1±0.5 24±5 St. Jude 3.0±0.8 12±3 Medtronic-hall 2.6±0.3 12±3 The various methods used in computation of valve areas are a) Cardiac out put method as described by Holen et al 16, b) Pressure half time method described by Hatle et al 17, c) Continuity equation method, and d) Performance index method. We calculated effective orifice area by pressure half time because the area computed is independent of the presence of prosthetic valve incompetence. The effective orifice area across TTK Chitra valve (27 mm) in mitral position and TTK Chitra valve (21 mm) in aortic position was comparable to other mechanical valves, as shown in the Tables 7 and

5 IJTCVS Pawan et al 121 Conclusion The TTK Chitra valve is hemodynamically comparable to other mechanical valves currently in use worldwide. The valve related complications are similar to other mechanical valves, however, a longer follow up will be necessary to assess long-term results. References 1. Bhuvaneshwar GS, Muraleedharan CV, Arthun Vijayan C, Sankar kumar R, Valiathan MS, Development of the Chitra tilting disc heart valve prosthesis. J Heart Valve Dis 1996; 5: Shekhar Rao, Kurian VM, Ghosh M, Sankar kumar R, Mohan singh MP, Valiathan MS, Clinical course after mitral valve replacement. Indian Heart J 1990; 42: Krishna Manohar SS, Valiathan, Sankar Kumar, Balakrishnan, Venkitachalam, GS Bhuvaneshwar, Experience with the Chitra prosthetic valve: Early results of Clinical trial. Indian J of Thorac and Cardiovasc Surg 1991; 7: Sankarkumar R, Bhuvaneshwar GS, Magotra MS et al. Chitra Heart valve: Results of a multicentre clinical study. J Heart Valve Dis 2001; 10: 5: Edmunds LH Jr, Clark RE, Cohn LH et al. Guidelines for reporting morbidity and mortality after cardiac valvular operations. J Thoarc Cardiovasc Surg 1996; 112: Grunkemeir GL, Li HH, Naftel DC et al. Long-term performance of heart valve prostheses. Curr Probl Cardiol 2000; 25: Butchart EG, Li HH, Payne N. Twenty years experience with the Medtronic hall valve. J Thorac Cardiovasc Surg 2001; 121: Jamieson WRE, Miyagishima RT, Grunkemier GL, et al. Bileaflet mechanical prostheses performance in mitral position. Eur J Cardiothorac Surg 1999; 15: Rahimtoola SH: The problem of valve prosthesis-patient mismatch. Circulation 1978; 58: Currie PJ, Stewart JB, Reeder GS etal, Continuous wave Doppler echocardiographic assessment of severity of calcific aortic stenosis, A simultaneous Doppler, catheter correlative study in 100 adult patients. Circulation 1985; 71: Soo CS, Ca M, Tay M, Yeoh JK, Sim E, Choo M, Echocardiographic assessment of Carbomedics prosthetic valves in mitral position. J Am Soc Echocardiogr. 1994; 7: Panidis I P, Ross J, Mintz GS, Normal and abnormal prosthetic valve function as assessed by Doppler echocardiography. J Am Coll Cardiol. 1986; 8: Reisner SA, Meltser RS, Normal values of prosthetic echocardiographic parameters: a review. J Am Soc Echocardiogr. 1988; 1: Vongpatasin W, Hills LD et al, Prosthetic heart valves. N Engl J Med 1996; 335: Nagarajan M, Muraleedharan, Chandrasekhar P, The TTK Chitra heart valve- A single center experience with midterm results Ind. J Thorac Cardiovasc Surg 2000; 16: Holen J, Aaslid R, Landmark K, Simonsen Severe, Ostrem T, Determination of effective orifice area in mitral stenosis from non-invasive ultrasound Doppler data and mitral flow rate. Acta Med Scand. 1977; 200: (A). 17. Hatle L, Angelson B, Transdol A, A non-invasive assessment of atrioventricular pressure half-time by Doppler ultrasound. Circulation 1979; 60: Edmunds Henry L, Cohn Lawrence. Mechanical and bioprosthetic mitral valve replacement. Chapter 34. Cardiac surgery in Adults, 2 nd Edition. The McGraw Hill companies Inc. 19. Edmunds Henry L, Cohn Lawrence. Mechanical and bioprosthetic aortic valve replacement. Chapter 29. Cardiac surgery in Adults, 2 nd Edition. The McGraw Hill companies Inc. 121