Doppler echocardiographic assessment of TTK Chitra prosthetic heart valve in the mitral position.

AIMS: TTK Chitra heart valve prosthesis (CHVP), a tilting disc mechanical heart valve of low cost and proven efficacy, has been in use for the last 15 years. Although various studies substantiating its long-term safety and efficacy are available, no study had assessed its echocardiographic characteristics. The purpose of this study was to determine the normal Doppler parameters of CHVP in the mitral position and to assess whether derivation of mitral valve area (MVA) using the continuity equation (CE) and more commonly used pressure half-time (PHT) method is comparable in the functional assessment of this tilting disc mitral prosthesis. METHODS AND RESULTS: Doppler echocardiography was performed in 40 consecutive patients with CHVP in the mitral position. All patients were clinically stable, without evidence of prosthetic valve dysfunction such as significant obstruction or regurgitation, endocarditis, left ventricular dysfunction (ejection fraction <40%), or significant aortic regurgitation. Valve sizes studied included 25, 27, and 29 mm. Mitral valve area was derived both by the PHT method and by the CE, using the stroke volume measured in the ventricular outflow tract divided by the time-velocity integral of CHVP jet. The peak Doppler gradient ranged from 5 to 21 (mean 11.0) mmHg, and the mean gradient ranged from 1.7 to 9.2 (mean 4.1) mmHg. Mean gradient negatively correlated with an increase in the actual orifice area (AOA) derived from the valve orifice diameter given by the manufacturer (r = -0.45, P = 0.004). Mitral valve area calculated by both PHT and CE increased significantly with an increase in the AOA (r = 0.42, P = 0.007 and r = 0.32, P = 0.046, respectively). Mitral valve area by the CE averaged 1.55 +/- 0.36 cm(2) (range 0.85 cm(2) for a 25 mm valve to 2.41 cm(2) for a 29 mm valve) and was smaller than by PHT (mean 2.04 +/- 0.41 cm(2), range 1.40-3.14 cm(2); P = 0.0001; t-test), irrespective of whether PHT is less than or >110 ms. CONCLUSION: The Doppler parameters obtained with CHVP in the mitral position are comparable with those obtained with the different prosthetic valves in common use. In the selected group of patients with CHVP, assessment of MVA by the PHT method is comparable with that by the CE. Areas by both methods were smaller than the AOA provided by the manufacturer, as seen in other similar design valves.

Retrograde cerebral perfusion for treatment of air embolism after valve surgery.

Air embolism occurred after termination of cardiopulmonary bypass in a 22-year-old man undergoing aortic valve replacement for rheumatic aortic insufficiency. Normothermic retrograde cerebral perfusion was instituted for 5 min at a flow rate of 300-500 mL.min(-1), maintaining internal jugular vein pressure < 25 mmHg. The aortic cannula was declamped intermittently for 5-10 seconds. Mean arterial pressure was kept at 60-70 mmHg. The patient recovered without any neurological deficit.

Chitra heart valve: results of a multicenter clinical study.

BACKGROUND AND AIM OF THE STUDY: The Chitra tilting disc valve was developed in India to meet the need for a low-cost cardiac valve. The valve has an integrally machined cobalt-based alloy cage, an ultra-high molecular-weight polyethylene disc, and a polyester suture ring. An important feature of this valve is its soft closing sound, by virtue of a plastic occluder. METHODS: Between December 1990 and January 1995, 306 patients underwent isolated aortic (AVR, n = 101) or mitral valve replacement (MVR, n = 205) at six institutions in India. The early mortality rate was 6.9% (seven after AVR; 14 after MVR). A total of 285 survivors was followed up until September 1998; total follow up was 1212 patient-years (pt-yr) (AVR, 445 pt-yr; MVR, 767 pt-yr). RESULTS: There were 52 late deaths (4.3%/pt-yr; AVR 2.2%/pt-yr; MVR 5.5%/pt-yr). Thirty-five deaths were valve-related (23 were due to unknown causes). One AVR patient (0.2%/pt-yr) and 12 MVR patients (1.6%/pt-yr) developed valve thrombosis, and embolic episodes occurred in 25 patients (seven after AVR, 1.6%/pt-yr; 18 after MVR, 2.4%/pt-yr). Bleeding events and infectious endocarditis occurred infrequently (AVR 0.9 and 0.7%/pt-yr; MVR 0.4 and 0.5%/pt-yr, respectively). There was no incidence of paravalvular leak or structural dysfunction of the valve. Actuarial survival rates at seven years were 82.4+/-4.0% for AVR and 65.2+/-5.0% for MVR. During the same interval, thrombus-free and embolism-free survival after AVR and MVR occurred in 98.9+/-1.1% and 94.1+/-1.9%, and 92.3+/-2.8% and 82.1+/-5.7% of patients, respectively. Freedom from all valve-related mortality and morbidity at seven years was 81.5+/-4.1% after AVR, and 64.2+/-5.1% after MVR. CONCLUSION: The Chitra valve appears to be safe and to have performance comparable with that of other currently used tilting disc valves. This valve costs substantially less than other valves, and is therefore within reach of a larger subset of Indian patients.

A correlative study of the functional class and hemodynamic status following intracardiac repair of tetralogy of Fallot.

An attempt was made to correlate the NYHA Functional class with the hemodynamic status of 196 patients at an average of 21.2 months following the intracardiac repair of tetralogy of Fallot. 171 patients were in Functional class I (87.2%), 9 in class III (4.5%), 5 in class II (2.5%) and 11 in class IV (5.6%). Right and left heart catheterisation and cardiac angiography revealed the hemodynamic status of these patients to be excellent in 92 (46.4%), good in 37 (18.8%), satisfactory in 6 (3.0%) and unsatisfactory in 61 (31.6%). Whereas all patients in Functional class II, III and IV had unsatisfactory hemodynamic findings, patients in Functional Class I were hemodynamically heterogeneous and included excellent (53.8%), good (21.6%), satisfactory (3.5%) and unsatisfactory (21%) groups. The surgical technique did not seem to determine the functional status. While early reoperation is advisable for patients with functional disability, caution is necessary in considering reoperation for patients in Functional class I who have hemodynamic findings which are classified as unsatisfactory.

Clinical course after mitral valve replacement.

Two hundred and fifty patients underwent mitral valve replacement for rheumatic valvular disease during a 9-year period from January 1979 to December 1987. A maximum period of follow-up of 10 years and minimum of 1 year was achieved with a mean duration of 4.4 years. The follow-up covered 921 out of a possible 1006 patient-years and was 91.5 per cent complete. Of the patients, 58 (23.2%) were in class II, 145 (58%) were in class III and 47 (18.8%) belonged to class IV. The early mortality for patients in Class II, III and IV was 8.6 per cent, 15.8 per cent and 31.9 per cent respectively and the 3, 5 and 10 years actuarial survival rates for the entire group were 93 per cent, 87 per cent and 70 per cent. The event-free survival rates at the same intervals were 77 per cent, 63 per cent and 57 per cent respectively. Late deaths occurred in 18 (9.5%) of the patients. Twelve of these (66.6%) could be directly ascribed to a valve-related cause.

Surgical treatment of endomyocardial fibrosis.

Forty-six patients with endomyocardial fibrosis underwent endocardiectomy and replacement of tricuspid, mitral, or both atrioventricular valves between April, 1981, and October, 1984, at the Sree Chitra Tirunal Institute, Kerala State, India, which has a high incidence of the disease. Six patients were in New York Heart Association Functional Class III and 40 patients in Class IV. The operative mortality within 30 days of the procedure and late mortality during the first two years postoperation were 21.7% and 13%, respectively. Age under 15 years was a significant correlate of operative mortality (p = .05). Non-fatal thromboembolic episodes occurred in 6 patients during the two years of postoperative observation. The life table estimate of survival inclusive of operative mortality at two years was 67%. Despite high operative mortality, endocardiectomy with atrioventricular valve replacement is advisable for functionally disabled patients with endomyocardial fibrosis whose prognosis otherwise is dismal.

Surgical palliation for endomyocardial fibrosis: early results.

Endomyocardial fibrosis is a fatal disease of obscure aetiology which is notably prevalent in Uganda, Brazil, Kerala State in India, and certain other parts of the world. The main disability in the disease results from fibrotic obliteration of ventricular chambers and insufficiency of the mitral and tricuspid valves. The poor response to medical treatment and the bleak prognosis of the patients led to the introduction of endocardiectomy and replacement of the atrioventricular valves as a palliative procedure by Dubost and colleagues. The present report on the early results in 17 patients from Kerala State would support the continued use of this palliative procedure in endomyocardial fibrosis with severe disability.