COMPARATIVE STUDY OF AORTIC VALVE NEOCUSPIDISATION VERSUS AORTIC VALVE REPLACEMENT WITH AORTIC VALVE PROSTHESIS- A NON INFERIORITY TRIAL

Aim

To compare short term outcomes after aortic valve replacement using aortic valve prosthesis –mechanical / bioprosthetic valves versus aortic valve neocuspidisation using glutaraldehyde treated autologous pericardium

Objectives

·         To compare the NYHA grade of symptoms between  AV prosthesis and AV Neo group

 Â·         To compare mean & peak gradient across AV prosthesis and AV Neo group at the end of 1mnths, 6mnth using Transthoracic 2d echocardiography.

·         To compare post operative complications and duration of ICU stay in both groups

·         To evaluate the incidence of complications like recurrence of AR/ AS, infective endocarditis, suture dehiscence, paravalvular leak or stuck valve /root abscess in both groups during follow up period.

Materials & Methods

Study design: An ambidirectional non inferiority trial

Study duration: January 2023 to June 2024

Source of data: All patients of aortic valvular heart disease (AS&AR) who underwent isolated AVR/AV neo from January 2020 and who will consent to undergo AVR/ AV neo in January 2023 to June 2024 at PGIMER CTVS Department.

M1

Mean indexed geometric aortic valve area in Group 1

1.77*

|M2

Mean indexed geometric aortic valve area in Group 2

1.46*

|S1

S.D of geometric aortic valve area in Group 1

0.54*

|S2

S.D of geometric aortic valve area in Group 2

0.36*

|S

Pooled SD

0.45

|AH

Two sided

2

|1-α

level of confidence

0.95

|1-β

level of power of test

0.8

|Z1

Z value associated with alpha

1.95

|Z2

Z value associated with beta

0.84

|N

Minimum sample size

35

Substituting the values in the above formula, sample size obtained is 35

Since there are 2 groups, sample size is 35*2=70.

Considering 10% attrition rate, total sample size is 70+7= 77 (rounded off to 80- 40 per group)

 Methodology

Demographic data & detailed history will  be  taken  including  mode of onset, duration  and progress of symptoms will be made. Detailed physical examination will be done. All  the  patients  will  undergo  following investigations- Complete Hemogram, Renal & Liver function tests, serum electrolytes, coagulation profile, electrocardiography, Chest X ray PA view, Transthoracic 2d echo, Coronary angiography-for pts > 40yrs & ECG gated CT Aortogram.

In  retrospective group, all the patients who underwent  AV neo and AVR  in our institution from year January 2020 till start of study period will be called telephonically and their status assessed. Their medical records will be reviewed as per the parameters mentioned in the proforma. They will be called for follow up and their Transthoracic 2d echoes will be reviewed.

Inclusion criteria:

All patients who will undergo  AV Neo cuspidisation for aortic valve disease and AV Replacement either by mechanical/ bioprosthetic valve

Exclusion criteria:

1)Patients undergoing concominant procedure like cabg/other valve surgery along with aortic valve surgery.

2. Patients who do not give consent for participation in the study

Trans-thorarcic Echocardiography

Transthoracic 2D Echocardiography will be done by Philips EPIQ 7C using probes S5(pediatric age group)/ S8( Adults) in Department of Cardiology by an expert. Patient will be positioned supine and in  Parasternal long axis view, the following parametes will be assessed. Presence of Aortic Calcification, sizes of Aortic annulus, Sinus of valsalva, Sinotubular Junction, Ascending aorta, & Descending Thoracic Aorta,LVEF .LVed, LVes & LV dimensions are measured using M mode on Parasternal long axis view.

Patient will be placed in left lateral position & 5 chamber view will be used to assess AV Gradient, Mean velocity & Peak velocity,

ECG Gated CT Aortogram: It will be used to assess Aortic valve anatomy, presence of Calcification, dimentions of Aortic annulus,Sinus of valsalva, Sinotubular Junction, Ascending aorta, Descending Thoracic Aorta & to know the Status of coronaries

Surgical technique:

All the patients will be induced according to the standard protocols followed in our institution

Prior to bypass TEE will be performed using Philips EPIQ 7C probe by an expert.

Median sternotomy will be  done after vertical midline incision extending just inferior to suprasternal notch to xiphisternum. After sternal division, a sternal retractor will be placed with ratchet positioned at the upper end of the wound.

AVR group:

The pericardium will be incised vertically down till its attachment to diaphragm, & then retraction sutures will be placed.

Aortic cannulation pursestrings :

Just proximal & to left of innominate artery origin, two opposing diamond shaped pursestrings will be placed using double armed 4/0 polypropylene sutures each.

Venous cannulation pursestring:

A 4/0 polypropylene pursestring suture will be placed in the right atrial appendage

Arterial cannulation:  EOPA straight Aortic cannula will be usedAfter heparinization, either 24F,22F/ 20F aortic cannula will be used based on Bodysurface Area.A transverse incision equal to diameter of the cannula will be placed, & cannula tip will be passed into the lumen in one single movement. Then the pursestrings will be snugged & it will be connected to arterial line.

Venous cannulation: The atrial appendage within the pursestring will be opened using scissors and the dual stage venous cannula will be passed caudally, posteriorly & slightly laterally into inferior venacava. The pursestring will then be snugged.

Vent: Left Superior Pulmonary Vein will be cannulated and used as vent.

Cardioplegia: Depending on the pathology either antegrade aortic root cardioplegia or ostial cardioplegia will be used. If there is no AR or mild AR, heart will be arrested using antegrade aortic root cardioplegia after cross-clamping the ascending aorta. However in cases with significant AR, fibrillatory arrest will be used with aortic crossclamp. Oblique aortotomy will be performed and the heart arrested with ostial cardioplegia, first to left coronary ostium and the to the right coronary ostium.

Thereafter, stay sutures are placed at the aortotomy to facilitate exposure.

After adequate exposure is achieved, the valve is excised. Valve excision is typically performed with scissors and scalpel, applying countertraction on the corresponding leaflet with heavy forceps. When valve excision and decalcification of the annulus is completed, the left vent is stopped, and the LV cavity is irrigated with normal saline to remove any debris or calcium particles from the operative field

2/0 nonabsorbable polyester braided pledgeted sutures ( Ethibond, Ethicon Inc.) are used to implant the prosthesis. With the interrupted horizontal mattress suture technique, sutures are first placed circumferentially around the annulus, starting from the LCC then to RCC and finally NCC, such that the pledget is on the aortic side. Valve is then sized using appropriate sizer. The sutures are then placed in the sewing ring of the Prosthetic valve.

After finishing each sector, a rubber shod is placed on the sutures, and the needles are removed. When all sectors are finished, the Prosthetic valve is parachuted down into the aortic annulus. Before tying the annular sutures, the proper suture order and the position of the prosthetic valve should be verified. The prosthetic valve holder is removed, taking care to completely remove all holding sutures. Annular sutures are tied with 6-8  square knots and cut. The aortotomy is closed in 2 layers with a continuous 4/0 Prolene (Ethicon Inc.) suture with pledgets, starting from the two ends of the incision, working toward the midline.

After the aortotomy is closed, the heart is filled up, and the lungs are gently inflated to dislodge any air bubbles from the pulmonary veins to the left atrium. During de-airing, the left vent is stopped, and gentle suction is applied to the aortic root vent to evacuate any entrapped air from the left side of the heart. If no more air is seen exiting through the aortic vent, flows are temporarily reduced, and the cross-clamp is removed.

AV Neo group

Under general anaesthesia , median sternotomy will be done. Pericardium will be harvested. Preparation of autologous pericardium will be initiated by cleansing fat and other redundant tissue on the outer surface of the pericardium. At least 7×8 cm will be harvested avoiding injury both phrenic nerves. Then, the excised pericardium will be treated with 0.6% glutaraldehyde solution for 7min. The treated pericardium will be rinsed for 6 min three times using normal saline solution. CPB initiated after cannulation as explained above.ACT will be maintained above 450s. The heart will be arrested using either antegrade /retrograde cardioplegia. Transverse aortotomy will be done and aortic valve morphology will be assess.ed. Firstly, diseased leaflets are excised meticulously. Decalcification will be done meticulously. Then, the distance between each commissures is measured with a sizing apparatus. Two horns of  sizer should be correctly placed at the commissures. The new leaflet of the size corresponding to the measured value is trimmed with a template from glutaraldehyde-treated autologous pericardium. Finally, the annular margin of the pericardial leaflet will be running sutured with 4-0 monofilament  to each annulus. Commissural coaptation will be secured with additional 4-0 monofilament sutures. The coaptation of three new leaflets will be always insured with direct vision under negative pressure made by a left ventricular vent before closure of the aortotomy.

Post CPB TEE will be performed to look for gradient, presence of residual AR, LV function

Transthoracic 2d echocardiography will be repeated at post op day 7 and at 1month and at end of 6months and the parameters present in the proforma will be assessed in both groups.

 For the retrospective part of the study all the patients who underwent AV neo/ AVR from 2020 onwards will be evaluated based on mortality, persistence of symptoms, AV gradient, LVEF, complications- paravalvular leak, calcification, redo surgery, suture dehiscence,& infective endocarditis.

STATISTICAL ANALYSIS

SPSS (Statistical Package For Social Sciences) version 20. (IBM SPASS statistics [IBM corp. released 2011] will be used to perform the statistical analysis

·         Data will be entered in the excel spread sheet.

·         Descriptive statistics of the explanatory and outcome variables will be calculated by mean, standard deviation/median and IQR (based on normalcy test- Shapiro wilk test) for quantitative variables, frequency and proportion for qualitative variables.

·         Inferential statistics like

·         Chi-square test will be applied for qualitative variables.

·         Independent sample t test/Mann-whitney test (based on data distribution) will be applied to compare the quantitative variables between the groups.

·         The level of significance is set at 5%

·         Data will be represented graphically wherever necessary using Pie diagram, Bar graph

·         Any other necessary tests/ graphs found appropriate will be dealt at the time of analysis based on data distribution.