Kerala Heart Journal -Ravikrishnan

Original article

Kerala Heart J  2016; 6(2):xx-xx.  



TOTAL CHORDAL APPARATUS VERSUS POSTERIOR MITRAL LEAFLET PRESERVATION IN MITRAL VALVE REPLACEMENT FOR RHEUMATIC MITRAL VALVE DISEASE IN SOUTH INDIAN POPULATION
 
Ravikrishnan J , Varghese George

 

Corresponding author


Dr. Ravikrishnan. J MS, M.Ch.
Associate Professor
Department of Cardiothoracic and vascular surgery
Pushpagiri Institute of Medical Sciences & Research Center
Thiruvalla, Kerala, India. 689101
E-mail: vu3jkr@gmail.com


ABSTRACT

 

BACKGROUND

            A fully functional mitral valve chordal apparatus with preserved annulo- ventricular continuity is important for the long term improvement of left ventricular function in patients undergoing mitral valve replacement. In this study, we compared the long term results of total mitral chordal apparatus preservation to posterior mitral leaflet preservation in South Indian patients undergoing mitral valve replacement in rheumatic mitral valve disease in terms of left ventricular ejection fraction (%) and left ventricular dimensions (mm).

MATERIALS AND METHODS

            190 patients of South Indian origin with rheumatic mitral valve disease, who underwent classical mitral valve replacement with St. Jude bileafelet mechanical valves, were divided into equal and comparable groups and included in this study. 91 (Group 1) had total mitral valve chordal apparatus preservation, 99 (Group 2) had posterior mitral leaflet preservation were used. All ventilated with minimal inotropic support and Amiodarone for fast ventricular rates. Follow up done by LVEF and LV dimensions assessment by 2D Echocardiography at 6 months and 2 years postoperative period.

RESULTS

            2 from Group 1 and 5 from Group 2 died of arrhythmias. Left ventricular ejection fraction for Group 1 pre-operatively, after 6 months & 2 years (43.46(5.13), 60.54(4.04) & 63.1(0.98)) showed improvement as compared to Group 2 (42.82(5.36), 50.2(4.84) & 54.15(4.43)). Left ventricular dimensions (end systolic/ end diastolic) for Group 1, pre-operatively, after 6 months & 2 years (55.62(2.77)/35.95(2.53), 40.06(2.48)/25.76(2.78) & 38.4(1.23)) was significantly better as to Group 2 (54.96(3.87)/35.81(2.12), 47.56(5.11)/29.72(4.6) & 44.3(7.48)/25.6(3.15)).

CONCLUSION

            Mitral valve replacement with total mitral chordal apparatus preservation had significant long term improvement of left ventricular ejection fraction and left ventricular dimensions as compared to posterior mitral leaflet preservation, in South Indian patients with rheumatic mitral valve disease.

 

KEY WORDS: Rheumatic heart disease; Mitral valve; Chordae tendinae; left ventricular Function,

 

INTRODUCTION

Rheumatic heart disease (RHD) is a still a problem in developing countries and results in approximately 250,000 deaths worldwide a year. This occurs due to an abnormal reaction against Group A beta hemolytic streptococcal infection, in a person who is genetically susceptible, with maximum damage caused by the sequelae of rheumatic carditis with irreversible damage to the valves and heart failure.1 There has been consensus regarding long term antibiotic prophylaxis against recurrent episodes of rheumatic fever and also echocardiographic screening of children in endemic areas, but these services are yet to be made available to those living in developing counties.2

In India, the burden of RHD has always been of significant public health importance. The younger age of onset of the disease and the delay in diagnosis is seen as having major public health importance, in control of RHD in the country.3 Extensive surveillance data on RHD is now available in the public domain as a result of community based studies focusing on rheumatic fever. In a study done in Rupnagar district of Punjab, it was found that the prevalence of rheumatic fever/ rheumatic heart disease was 143/100,000 population and the annual incidence was 8.7/100,000 population.4 Some other studies have indicated higher numbers, with a study done in Shimla reporting a prevalence as high as 298/100,000 population. This study also showed that rural residence, those living in crowded conditions and poor socioeconomic status were risk factors for rheumatic heart disease in children.5

The Mitral valve is the most commonly damaged structure in case of RHD. Echocardiographic and autopsy based studies have shown that more than 50% of the patients with RHD shows some damage to the mitral valve.6 Also, mitral valve surgery presents with its own difficulties in view of valve deformity and complexity of lesions, but still remains the gold standard treatment option for rheumatic mitral valve disease.7

In this study, we aimed at assessing and comparing the long term outcome for mitral valve replacement with total chordal apparatus preservation and mitral valve replacement with posterior mitral leaflet preservation , in terms of improvement in left ventricular ejection fraction (LVEF) and left ventricular (LV) dimensions (end systolic and end diastolic).

MATERIALS AND METHODS:

The study was observational in nature and was done in the department of Cardiothoracic and Vascular Surgery at Sri Venkateswara Institute of Medical Science, Tirupati, India, from 2008-2010. A total of 190 patients, suffering from isolated rheumatic mitral valve disease, who required mitral valve replacement, of South Indian origin, were enrolled into the study after obtaining written informed consent and Institutional Ethics Committee clearance. Of this 91 participants underwent mitral valve replacement with total mitral chordal apparatus preservation (Group 1), and the rest had mitral valve replacement with posterior mitral leaflet preservation (Group 2). The two groups were comparable in age, sex ratio and preoperative LVEF and LV dimensions.

In all patients, general anesthesia was induced by midazolam, fentanyl, and propofol. Ventilation was controlled with oxygen and anesthesia maintained by inhalational isoflurane, propofol, and fentanyl. After induction, all were approached through median sternotomy and classical left atrial approach. After systemic heparinisation (3mg/kg), aorto bicaval cannulation was employed and patients were maintained on normothermic cardiopulmonary bypass (34-370C), with Sarns 9000 heart-lung machine (3M Health Care, Ann Arbor, MI, USA) using Edwards membrane oxygenator. After aortic cross clamping, cold blood cardioplegia (40C) was employed in all cases.

In Group 1, mitral valve replacement was performed with care taken in preserving the mitral valve chordal apparatus, thus ensuring annulo-ventricular continuity. The mitral valve leaflets were debulked and decalcified in such a manner that a small wedge of valve tissue was left behind on the anterior and posterior leaflets, attached to the primary chorde and the annulus. In Group 2, anterior mitral valve leaflet and its chordal attachments were excised, keeping wedges of the posterior mitral leaflet with its chordal attachments intact and attached to the annulus.

St. Jude bileafelet mechanical valves were used in all cases. 2-0 double armed pre-pledgeted ethibond sutures were used to fix the valve on to the annulus. Cross clamp time ranged from 20-40 minutes (30.74(3.46)) and bypass time was 30-60 minutes (48.09(2.79)).

After releasing aortic cross clamp, all patients were uneventfully weaned off bypass and was shifted to the intensive care unit on minimal dose of inotropes (Dopamine or Adrenaline). 35 patients developed fast ventricular rates for whom Amiodarone infusion was administered. 11 patients were re-explored due to bleeding. All the participants were ventilated postoperatively in intensive care unit. Two patients in Group 1 and 5 patients in Group 2 died during the postoperative period, due to low cardiac output.

The patients were followed up for 2 years after the surgical intervention. This was done by 2D Echocardiography at 6 months and 2 years. LVEF was noted at 6 months and 2 years and was compared with pre-operative data. Left Ventricular dimensions in terms of diastolic and systolic diameters were also observed likewise.

The data was collected by the investigators and was digitized using a data entry platform made using Epi-Info 7.0. The data analysis was done using SPSS. 17.0, a statistical package marketed by IBM Inc., USA. A p value <0.001 was considered statistically significant. All observations are expressed as Mean (SD).

RESULTS:

Demographics

Out of the total 190 patients in the study, 91 underwent mitral valve replacement with total chordal apparatus preservation (Group 1), and 99 had mitral valve replacement with posterior mitral leaflet preservation (Group 2). The age ranged from 25-60 years (41.98(7.23)). There were 105 males and 85 females in the study population. The major comorbidities included Type II Diabetes mellitus in 35 patients (18.4%), Hypertension in 54 patients (28.4%), COPD in 41 patients (21.57%), Pulmonary hypertension in 123 patients (64.7%), Atrial fibrillation in 123 patients (64.7%) and history of cerebrovascular accidents in 6 patients (0.31%). (Table 1)

Table 1: Baseline patient demographics

Demographic Parameters

Values

Age (years)

41.98(7.23)

Sex ratio (M:F)

105:85

Comorbidities

Disease

Number of patients

Type II Diabetes Mellitus

35(18.4%)

Hypertension

54(28.4%)

COPD

41(21.57%)

History of CVA

6(0.31%)

Pulmonary Hypertension

123(64.7%)

Atrial Fibrillation (>6 months)

123(64.7%)

 

Surgical data

            93 patients had previous cardiac surgical procedures. In Group 1, 17 had closed mitral valvotomy (CMV), 25 had open mitral valvotomy (OMV) and 9 had balloon mitral valvoplasty (BMV). In Group 2, 10 had CMV, 20 had OMV and 11 had BMV, which was statistically not significant (p>0.001).  The aortic cross clamp time and bypass time for Group 1 were 31.57(1.6) and 48.09(2.79) and for Group 2 30.18(2.35) and 47.95(3.56). (Table 2)

 

Table 2. Surgical data

Parameters

Group 1

Group 2

p value#

Previous Surgeries

Closed mitral valvotomy (CMV)

17

10

>0.001

Open mitral valvotomy (OMV)

25

20

>0.001

Balloon mitral valvotomy (BMV)

9

11

>0.001

Bypass time (min)

48.09(2.79)

47.95(3.56)

>0.001

Aortic cross clamp time (min)

31.57(1.6)

30.18(2.35)

>0.001

# Wilcoxon Signed Rank test

            The long term outcome of mitral valve replacement by total mitral chordal apparatus preservation technique against that of posterior mitral leaflet preservation was done by comparing and analysing the LVEF (%) and LV dimensions (mm), both systolic and diastolic, during preoperative period and at 6 months and 2 years post-operative follow up. In Group I, LVEF improved significantly from 43.46(5.13) preoperatively to 60.54(4.04) and 63.1(0.98) at 6 months and 2 years postoperative period respectively. In Group 2, preoperative LVEF was 42.82(5.36) and at 6 months and 2 years postoperative periods were 50.2(4.84) and 54.15(4.43). There was statistically significant improvement in left ventricular function in terms of LVEF in Group 1 as compared to Group 2 (p<0.001).

            LV dimensions (systolic/diastolic) were also analysed preoperatively and at 6 months and 2 years postoperative period. Group 1 had values of 35.95(2.53)/55.62(2.77), 25.76(2.78)/40.06(2.48) and 20.6(3.5)/38.4(1.23) respectively. In Group 2 the values were 35.81(2.12)/54.96(3.87), 29.72(4.6)/47.56(5.11) and 25.6(3.15)/44.3(7.48) respectively. This showed marked improvement in the left ventricular dimensions I Group 1 as compared to Group 2 (p<0.001). (Table 3)

 

Table 3. Preoperative and postoperative (6 months and 2 years) LVEF and LV dimensions (systolic/diastolic)

Parameter

Group 1

Group 2

p value#

LVEF (%)

Preoperative

43.46(5.13)

42.82(5.36)

>0.001

Postoperative

 6 months

60.54(4.04)

50.2(4.84)

<0.001

 2 years

63.1(0.98)

54.15(4.43)

<0.001

LV Dimensions (mm)

(End Systolic/ End Diastolic)

Preoperative

Systolic

35.95(2.53)

35.81(2.12)

>0.001

Diastolic

55.62(2.77)

54.96(3.87)

Postoperative

6 months

Systolic

25.76(2.78)

29.72(4.6)

<0.001

Diastolic

40.06(2.48)

47.56(5.11)

2 years

Systolic

20.6(3.5)

25.6(3.15)

<0.001

Diastolic

38.4(1.23)

44.3(7.48)

# Mann-Whitney U test

DISCUSSION:

Participants who underwent both the surgical procedures showed significant improvement in left ventricular function and size. The short term physiological improvement, measured as improvement in LVEF, at the end of 6 months postoperative period, was significantly better with the patients who had mitral valve replacement with total chordal apparatus preservation than those who had posterior mitral leaflet preservation. Long term improvement, as measured by decrease in left ventricular systolic size, was better in those who had total chordal apparatus preservation. Other studies have also demonstrated the efficacy of this type of procedure. A study by Chowdhury UK et al showed that in those who underwent chordal preservation, the left ventricular ejection fraction, end diastolic volume and end systolic volumes were significantly better than other procedures and results were comparable to the present study.8

A randomised control trial done by Yun KL et al also demonstrated that total chordal apparatus preservation is significantly better than partial preservation, in terms of clinical and echocardiographic improvement. They also stated that the left ventricular ejection fraction continued to improve over time in the patients who had total chordal apparatus preservation, probably due to a process of favorable cardiac remodeling.9 Studies have shown that posterior mitral leaflet preservation procedure is beneficial in a section of patients who have mitral regurgitation. The procedure has reduced efficacy in those patients with mitral stenosis, and showed sub-optimal improvement in left ventricular function on long term followup.10

Another important finding was the reduced level of left ventricular improvement showed by participants who had pulmonary hypertension. Although this parameter was not statistically evaluated in this study, studies have shown that patients with pulmonary hypertension are more at risk for early mortality and poor improvement following surgical intervention. But improved surgical techniques and perioperative treatment has improved the chances of a full recovery and nowadays mitral valve replacement is the recommended treatment modality for persons suffering from pulmonary hypertension.11

CONCLUSION

 In conclusion, mitral valve replacement with total mitral chordal apparatus preservation had significant long term improvement of left ventricular ejection fraction and left ventricular dimensions as compared to posterior mitral leaflet preservation, in South Indian patients with rheumatic mitral valve disease. The results were comparable to similar studies conducted in North Indian population also.

ACKNOWLEDGEMENT

            We thank all the patients, along with their families, the doctors, nurses and operation theatre staff of Sri Venkateswara Institute of Medical Sciences, Tirupati for their endless support. A special thanks to Dr. Philip Mathew, Assistant Professor, Department of Social and preventive medicine, for his help during the statistical analysis.

REFERENCES

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2.      Rheumatic fever and rheumatic heart disease. World Health Organ Tech Rep Ser. 2004;923:1-122
3.      Vijaykumar M, Narula J, Reddy KS, Kaplan EL. Incidence of rheumatic fever and prevalence of rheumatic heart disease in India. Int J Cardiol. 1994 Mar 1;43(3):221-8.
4.      Kumar R, Sharma YP, Thakur JS, Patro BK, Bhatia A, Singh IP et al. Streptococcal pharyngitis, rheumatic fever and rheumatic heart disease: Eight-year prospective surveillance in Rupnagar district of Punjab, India. Natl Med J India. 2014 Mar-Apr;27(2):70-5.
5.      Thakur JS, Negi PC, Ahluwalia SK, Vaidya NK. Epidemiological survey of rheumatic heart disease among school children in the Shimla Hills of northern India: prevalence and risk factors. J Epidemiol Community Health. 1996 Feb;50(1):62-7.
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8.      Chowdhury UK, Kumar AS, Airan B, Mittal D, Subramaniam KG, Prakash R et al. Mitral valve replacement with and without chordal preservation in a rheumatic population: serial echocardiographic assessment of left ventricular size and function. Ann Thorac Surg. 2005 Jun;79(6):1926-33.
9.      Yun KL, Sintek CF, Miller DC, Pfeffer TA, Kochamba GS, Khonsari S, Zile MR.Randomized trial comparing partial versus complete chordal-sparing mitral valve replacement: effects on left ventricular volume and function. J Thorac Cardiovasc Surg. 2002 Apr;123(4):707-14.
10.  Djuki PL, Obrenovi-Kir anski BB, Vranes MR, Kocica MJ, Miki ADj, Velinovi  MM et al. Posterior leaflet preservation during mitral valve replacement for rheumatic mitral stenosis. Acta Chir Iugosl.2006;53(1):13-7.
11.  Cesnjevar RA, Feyrer R, Walther F, Mahmoud FO, Lindemann Y, von der Emde J. High-risk mitral valve replacement in severe pulmonary hypertension--30 years experience. Eur J Cardiothorac Surg. 1998 Apr;13(4):344-51

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 














































































































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