Minimaly invasive mitral valve repair with Neochord system in patients with degenerative mitral disease: echocardiographic assessment and predictors for mid-term outcome

Introduction

Various minimally invasive mitral valve (MV) repair techniques are available to treat degenerative mitral regurgitation (MR). Transapical implantation of artificial chordae on a beating heart is performed using the NeoChord DS1000 device with real-time TEE guidance.

Purpose

1)To assess preoperative and the mid-term follow-up echocardiographic data in patients after MV repair using the NeoChord DS1000 device; 2)to investigate the changes of left ventricle (LV), left atrium (LA) and mitral annulus dimensions during the follow-up period; 3)to assess the difference of baseline echocardiographic parameters between successful and not-successful (severe residual MR) MV repair groups; 4)to identify the preoperative echocardiographic variables that may be associated with recurrence of MR at mid-term follow.

Methods

All patients after transapical MV repair with Neochord implantation in Vilnius University hospital were prospectively entered into the study. The acquired preoperative and follow-up echocardiographic datasets were analysed. According to the residual MR at follow-up, patients were stratified to 2 groups: group A – successful durable MV repair (residual MR ≤2); group B – MV repair failure (recurrence of severe MR or reintervention). Values were expressed as Mean±SD. Univariable regression analysis was used to identify anatomical predictors of residual MR.

Results

53 (70.67%) patients had a residual MR ≤2 (Group A) and 22 (29.33%) residual MR≥2+ (Group B) at 26±6 months follow-up. At baseline, Group B patients had significantly larger left ventricle end diastolic diameter (LVEDD) (mean difference 5.67±1.29mm, p<0.0001) left ventricle end systolic diameter (LVESD) (mean difference 4.08±1.57mm, p=0.012), LA volume index (mean difference 21.57±5.003 p<0.0001) and higher systolic pulmonary pressure values (mean difference 10.46±3.34, p<0.003) compared with group A. Overall, a significant reduction in LA volume index (mean change 15.69±4.15ml/m2, p<0.001), LA diameter (mean change 3.15±1.24, p=0.012), LV diameter (mean change in LVEDD 4.78±0.88mm p<0.000) was observed at 24 months follow up. There was no significant changes in MV annular parameters at follow up. Left atrium volume (OR 1.018; 95% CI 1.006–1.035; p=0.009), left atrium volume index (OR 1.038; 95% CI 1.013–1.072; p=0.010), LVEDD (OR 1.201; 95% CI 1.088–1.353; p=0.0008), LVESD (OR 1.122; 95% CI 1.02–1.248); p=0.0236) and sPAP (OR 1.418; 95% CI 1.139–2.016; p=0.0014) were all significantly associated with the worse outcome (MR >2) after mini-invasive MV repair in univariable regression analysis.

Conclusions

Minimaly invasive MV repair with Neochord system on beating heart is effective in patients with degenerative MR. Baseline echocardiographic characteristics predictive for a worse middle term outcome are mainly related to LV and LA remodeling. Reverse remodeling of LV and LA is observed during the follow-up period with no significant changes in MV annulus.

Funding Acknowledgement

Type of funding source: None

P1412 A new light to improve the view of the anatomical details during micro-invasive trans-ventricular repair of degenerative prolapse of mitral valve

BACKGROUND

Mitral valve repair is the preferred surgical treatment for severe mitral regurgitation due to degenerative leaflet prolapse. Within the growing era of transcatheter treatments for valvular heart disease, an innovative micro-invasive trans-ventricular beating-heart procedure was developed. Three-dimensional (3D) transoesophageal echocardiographic guidance is crucial to assist the operator in instrument navigation and chords positioning. 3D ultrasound technology is constantly evolving and a special light, that can be mobilized within the 3D images, has recently been invented. This light allows to illuminate the structures from different points of view and increase the definition of the anatomical details.

PURPOSE

To show the advantages of this new 3D image analysis technology, described above, through a sequence of intra-procedural images of a mitral valve repair by trans-ventricular polytetrafluoroethylene (ePTFE) chords implantation.

METHODS

The procedure is performed using a device that is introduced through a posterolateral ventriculotomy and it is advanced towards the mitral valve under real-time 3D transoesophageal guidance. The prolapsing segment, in this case central part of posterior leaflet (Fig. 1 A, B and C), is grasped with the jaw of the instrument (J in Fig. 1D), then the chords are implanted, tensioned and secured outside the ventricle. Figure 1A shows the pre-operative image of posterior leaflet prolapse with flail (P2 segment) and the light illuminates the valve from above. The broken chords (arrow in Fig. 1A) can be recognized with high definition. The light can also be placed on the valve plane (Fig. 1B) or below (Fig. 1C). When illumination occurs from the left ventricular side, the coaptation loss due to the P2 flail is highlighted (arrow in Fig. 1C). After placement, tensioning and securing the chords outside the ventricle, the prolapse disappears and the correct coaptation is re-established (Fig. 1E). The coaptation deficit is no longer visible, even with the light placed below the valve and it is possible to see the light coming out of the aortic valve (Ao), opened in systole, with mitral valve closed (Fig. 1F).

RESULTS

At the end of the procedure the residual mitral regurgitation was trivial and no loss of coaptation can be evidenced even with the light placed in the left ventricle (Fig. 1F).

CONCLUSIONS

This new light allows to improve the anatomical definition of 3D echocardiographic images, allows better visualization of the coaptation defects and can be used as a further verification of the result especially in cases of micro-invasive mitral repair.

Abstract P1412 Figure 1

P951 Intraprocedural echocardiographic technique to locate the insertion points of artificial chordae during transventricular beating heart mitral valve repair: ultrasound ""starry sky""

BACKGROUND

Mitral valve repair is the preferred surgical treatment for severe mitral regurgitation due to degenerative leaflet prolapse. Within the growing era of transcatheter treatments for valvular heart disease, an innovative micro-invasive trans-ventricular beating-heart procedure was developed. Three-dimensional transoesophageal echocardiographic guidance is crucial to assist the operator in instrument navigation and chords positioning. Indeed, it is important an equidistant chords placement on the leaflet to ensure a uniform force distribution on the prolapsing segment and to avoid damaging of the previously inserted chords.

PURPOSE

To propose an intraoperative three-dimensional echocardiographic technique that allows operators to see the exact location of the polytetrafluoroethylene (ePTFE) chords used for the mitral repair.

METHODS

The procedure is performed using a device that is introduced through a posterolateral ventriculotomy and it is advanced towards the mitral valve under real-time 3D transoesophageal guidance. The prolapsing segments are grasped with the jaw of the instrument and the chords are implanted to achieve the proper distribution of forces and then tensioned and secured outside the ventricle.

The proposed technique exploits the greater echogenicity of the artificial chord loop compared to native chords and leaflets. By lowering of the gains, remaining in the three-dimensional mitral valve surgical view, the signals of the native structures are attenuated, the underlying ventricular cavity appears black and the insertion points are visible as an intense signal on the virtual free edge of the leaflet treated.

Figure 1 shows the intraoperative sequence of images of a case performed at our centre. The images were acquired using real time single beat three-dimensional reconstruction. Figure 1A shows the surgical view of the native valve with prolapse of the P2-P3 scallops. Image 1B reveals the prolapsing leaflet grasping and device location. After gain lowering, it’s possible to see the intense signal of the positioned artificial chord (Figure 1C). It can also be noted how this position matches with the position of the device at the time of grasping. Image 1D shows the partial disappearance of the prolapse during the tensioning test after the positioning of a second chord in a more medial position. Figure 1E shows the correct position of the ePTFE chords. We can notice the second chord placed in a medial position from the first one. This view, with dark ventricular chamber and intense signals of chordae loops, looks like a "STARRY SKY".

RESULTS

This technique allows to locate the correct insertion points of the artificial chords during the procedure.

CONCLUSIONS

This is a simple technique to guide operators during trans-ventricular beating heart mitral valve repair with ePTFE chords.

Abstract P951 Figure 1

Flow capacity of inferior epigastric artery in composite arterial grafts

BACKGROUND

In the effort to expand the use of arterial conduits for myocardial revascularization, 'Y-graft' techniques are utilized with increasing frequency, although the physiology of this type of composite arterial grafts is not yet fully understood. The aim of this study was to measure changes in blood flow through a 'Y-graft' constructed by anastomosing a segment of inferior epigastric artery (IEA) off the side of an in situ internal thoracic artery (ITA).

METHODS

Twenty-two patients who underwent CABG were enrolled in this prospective study. Exclusion criteria were age > 70 years, poor left ventricular function (Ejection Fraction < 0.25) and need for associated cardiac procedures. Blood flow in the TrA-IEA 'Y-graft' was measured in the operating room after completion of left ITA to left anterior descending artery (LAD) and IEA to marginal or diagonal branch anastomoses. Follow-up evaluation was performed at 3 and 12 months postoperatively.

RESULTS

After completion of surgery, blood flow in ITA and IEA as measured downstream from the Y anastomosis was 45+/-7 and 39+/-6 ml/min respectively. Temporary occlusion of either branch did not significantly affect flow in the other side of the arterial Y. All patients were discharged from the hospital in excellent condition. At follow-up no cases of angina recurrence were recorded.

CONCLUSIONS

Composite ITA-IEA arterial grafts provide excellent short-term clinical results. Blood flow on either side is not affected by run off in the other side branch. Information from this study may be used to understand the role that undivided ITA side branches play in reducing flow rate in an ITA graft harvested during minimally invasive CABG procedures.

Cardiac transplantation for end-stage congenital heart defects: the Mayo Clinic experience. Mayo Cardiothoracic Transplant Team

OBJECTIVE

To review the outcome of cardiac transplantation undertaken in patients with congenital heart defects.

MATERIAL AND METHODS

Between November 1991 and March 1998 at our institution, cardiac transplantation was performed in 16 patients with congenital heart disease (age range, 3 to 57 years; mean, 26.1). Preoperative diagnoses included univentricular heart (N = 4); complete transposition of the great arteries (N = 3); Ebstein's anomaly (N = 2); tetralogy of Fallot (N = 2); levotransposition (N = 2); dextrocardia, corrected transposition, ventricular and atrial septal defects, and pulmonary stenosis (N = 1); double-outlet right ventricle (N = 1); and hypertrophic obstructive cardiomyopathy (N = 1). All patients had undergone from one to five previous palliative operations.

RESULTS

Four patients required permanent pacemaker implantation during the first month postoperatively because of bradycardia; more than 2 years later, another patient required a permanent pacemaker because of sick sinus syndrome. In addition, one patient had an automatic implantable cardioverter-defibrillator. Three patients required reconstruction of cardiovascular structures with use of prosthetic material (Teflon patches or donor tissue) at the time of cardiac transplantation. Actuarial 1-, 2-, and 5-year survival was 86.2 +/- 9.1%. During the first year after transplantation, two deaths occurred--one at 41 days of putative vascular rejection and the second at 60 days of severe cellular rejection. All other patients are alive and functionally rehabilitated; the mean follow-up period has been 26.1 months (range, 2 to 89.6).

CONCLUSION

Cardiac transplantation for patients with congenital heart disease can be accomplished with a low perioperative mortality and an excellent medium-term survival despite the challenges presented by the technical difficulties during invasive diagnostic procedures and at operation and the need for adherence to long-term multiple-drug therapy in this patient population.

Myocardial revascularization through a mini-thoracotomy with thoracoscopic assistance

OBJECTIVE

Left internal mammary artery harvesting through a mini-thoracotomy makes gaining the proximal portion of this vessel very difficult and exposes the patient to the risk of chest wall trauma due to excessive spreading of the ribs. The adoption of video thoracoscopic assistance can give several advantages to the procedure.

METHODS

With the patient in a 30 degrees left-side-up thoracotomy position, a 8-12 cm anterior thoracotomy is performed in the left fourth or fifth intercostal space. Two thoracoscopic ports are inserted in the third and fourth left intercostal spaces in the midaxillary line. Complete mobilization of the left internal mammary artery is performed with a mixed surgical and thoracoscopic technique.

RESULTS

Since July 1996, 12 patients underwent myocardial revascularization with the left internal mammary artery through a mini-thoracotomy, with the aid of video assisted thoracoscopy. There were no deaths or perioperative infarctions. Mean hospital stay was 4 days (3-6). In nine patients a postoperative angiographic study was performed: in all cases the length of the mammary artery pedicle was adequate; one patient underwent a successful angioplasty on a narrowed anastomosis on the left anterior descending artery. In another patient the left internal mammary artery had been grafted to a diagonal branch. In all other cases angiography showed good results.

CONCLUSIONS

Thoracoscopic assistance helps achieving complete mobilization of the left internal mammary artery, maximizing its useful length, without an extended thoracotomy.

Native lung complications after single lung transplantation for emphysema

We reviewed the impact of the presence of the native diseased contralateral lung on the outcome after single lung transplantation for emphysema. Twenty consecutive recipients of single lung transplants for emphysema were reviewed for complications related to the native lung. Five patients (25%) suffered major complications arising in the native lung and resulting in serious morbidity and mortality. The timing of onset varied from 1 day to 43 months after transplantation. We conclude that the susceptibility of the native lung to complications such as those described in this report is an additional fact to be considered in choosing the ideal transplant procedure for patients with obstructive lung disease.

Infant thoracic surgery: procedure-dependent pulmonary response

Respiratory insufficiency is a common complication of thoracic surgery in infants. To better define this dysfunction, pulmonary compliance (CL) and resistance (R) were measured for 17 infants who underwent common thoracic procedures: Blalock-Taussing shunting (n = 7) repair of congenital coarctation of the aorta (n = 10). Measurements were obtained preoperatively and 0, 1, and 3 days postoperatively. Preoperatively, CL was lower and R was similar for the two groups. Both groups had decreased CL and increased R on postoperative day 0; infants with coarctation had recovery to preoperative values by postoperative day 1 for CL, and day 3 for R. CL and R did not return to the preoperative values by postoperative day 3 in infants with a shunt procedure. The changes in R were greater than those in CL for both groups in the postoperative period. These data indicate that such thoracic procedures are associated with pulmonary morbidity that is airway-predominant, and that the degree of compromise and the time until recovery are, in part, procedure-specific.

Effects of halothane on the immature lamb heart

The choice of anesthesia during pregnancy and fetal operations is controversial. Halothane frequently is used, but its direct effects on fetal cardiac performance are unknown. The effects of halothane on fetal cardiac mechanics were studied in 8 fetal lamb hearts (135 days' gestation) using a modified Langendorff model connected to a membrane oxygenator. The perfusate consisted of oxygenated maternal blood at a constant flow temperature, hematocrit value, and glucose level. Coronary blood flow, left ventricular systolic pressure, left ventricular end-diastolic pressure, and the developed left ventricular pressure at a fixed volume were evaluated at baseline and after the addition of incremental concentrations of halothane to the perfusate through the oxygenator. Perfusate halothane levels were maintained in a clinical range. Systolic and diastolic cardiac function were adversely affected by the administration of even low doses of halothane, despite a concomitant increase in coronary blood flow. Because of the immaturity of their calcium transport system, fetal hearts may be particularly sensitive to the known calcium channel-blocking properties of halothane.

Hypothermia enhances contractility in cerebral arteries of newborn lambs

Hypothermia is the major factor influencing autoregulatory properties of the cerebral circulation in human infants undergoing hypothermic cardiopulmonary bypass. The present investigation evaluated the effect of decreased temperature on the contractility of isolated middle cerebral arteries obtained from newborn lambs. Reducing bath temperature from 37 to 21 degrees C caused a temperature-dependent increase in contractile tension, achieving 1.32 +/- 0.09 g above resting tension (0.75 g). Pretreatment with nonselective (alpha 1 and alpha 2) alpha-adrenoceptor antagonist, phentolamine (10(-5) M), with an inhibitor of nitric oxide synthase, NG-nitro-L-arginine methyl ester hydrochloride (10(-4) M), and with a cyclooxygenase inhibitor, indomethacin (10(-5) M), did not affect the contractile response to a decrease in bath temperature from 37 to 21 degrees C. Furthermore, cerebral arteries were responsive to both norepinephrine (constriction) and sodium nitroprusside (relaxation) and the sensitivity of cerebral arteries to the sympathetic neurotransmitter norepinephrine appears to be enhanced at low temperatures. We postulate that direct cerebral vasoconstriction and enhanced adrenergic contractility may be responsible for increased cerebrovascular resistance during and after hypothermic cardiopulmonary bypass with possible ischemic cerebral injury and neurological sequelae.

High-frequency jet versus conventional ventilation in infants undergoing Blalock-Taussig shunts

Nine infants undergoing modified Blalock-Taussig shunts were randomized to both high-frequency jet ventilation (HFJV) and conventional ventilation (CV). Vital signs, blood gases, mean airway pressure, lung mechanics, functional residual capacity, and lung movement were compared on both modes of ventilation keeping peak inspiratory and expiratory pressures constant. The mean airway pressure was lower on HFJV than on CV (8.5 versus 10.9 cm H2O). Arterial partial pressure of oxygen was greater on HFJV than on CV (55 versus 46 mm Hg), arterial partial pressure of carbon dioxide was lower on HFJV than on CV (28 versus 37 mm Hg), whereas compliance (0.54 versus 0.56 mL.cm H2O-1.kg-1). resistance (110 versus 95 cm H2O/L.s), and functional residual capacity (23 versus 22.5 mL/kg) remained the same. Lung movement and degree of retraction necessary for surgical exposure as evaluated by an independent observer was less with HFJV compared with CV. Compared with CV during the creation of Blalock-Taussig shunts, HFJV provides better gas exchange at lower mean airway pressure with similar lung function, lung volume, and hemodynamics.

Echo-controlled endomyocardial biopsy

Endomyocardial biopsy is an essential procedure for the diagnosis and grading of rejection in heart transplant patients. Direct control of the bioptome positioning has classically been obtained by fluoroscopy. Starting in June 1988, at our institution an alternative approach involving the use of two-dimensional echocardiography was introduced in clinical practice. In 125 patients 1591 biopsies have been performed: 445 under echographic control and 1146 under fluoroscopic control with 3.6 and 4.5 samples/biopsy, respectively. The percentages of inadequate samples caused by biopsy site sampling were 0.4% and 1.3%, respectively, in the two groups. Cardiac perforation has occurred twice in the fluoroscopic group; it has not been observed in the echographic group. One case of iatrogenic tricuspid regurgitation was detected in each group. We now consider echocardiography the method of choice to guide the bioptome. We prefer it to fluoroscopy because it eliminates the risks of x-ray exposure, increases the number of sampling sites in cases of echocardiographic evidence of rejection, can be easily performed as a bedside procedure, allows choice and variation of sampling sites, and permits monitoring of cardiac complications during and after the procedure. A randomized clinical trial is probably needed to assess with statistical significance the superiority of the echographic-controlled biopsy.