Management of acute left main obstruction after transcatheter aortic valve replacement: the “tunnel technique”

Two cases of acute left main (LM) obstruction complicating transcatheter aortic valve replacement (TAVR) and their management are reported. TAVR with a self-expandable transcatheter aortic prosthesis was performed for treating severe aortic stenosis with small aortic root and severe aortic regurgitation of a degenerated stentless bioprosthesis, respectively. Left main coronary obstruction occurred at a different time from the index procedure. A novel stent-based angioplasty treatment, denominated “the tunnel technique,” was successfully applied in both cases and herein described.     

Does the type of prosthesis influence early left ventricular mass regression after aortic valve replacement? Assessment with magnetic resonance imaging

Background

Debate exists regarding selection of the prosthesis type most likely to maximize early left ventricular (LV) mass regression after aortic valve replacement (AVR) for stenotic valvular disease. The aim of this study was to compare the degree of LV mass regression measured by MRI 6 months after prospectively randomized valve implantation for two biological prostheses, stented and stentless, and for two mechanical valves, tilting disc and bileaflet.

Methods

Thirty-nine consecutive patients with predominant aortic stenosis accepted for elective AVR were studied. Twenty patients requiring a tissue prosthesis were randomly assigned to receive either a Freestyle or Mosaic valve. The remaining 19 patients in whom mechanical prosthesis was indicated were randomly assigned to receive either an Ultracor or an ATS valve.

Results

There was no difference in valve size implanted between the compared groups. LV mass measurements were performed with MRI (1.5-T Vision, Siemens, Germany) immediately before and 6 months after surgery. All valve types produced significant postoperative reduction in LV mass compared with preoperative values (P < .01). Percent change in LV mass regression was similar between the two porcine valve types, Mosaic (24.4% ± 11.1%) and Freestyle (21.1% ± 16.7%), and between the two mechanical valve designs, Ultracor (19.3% ± 9.5%) and ATS (26.3% ± 10.8%), respectively.

Conclusions

Significant LV remodeling occurs early after AVR for aortic stenosis. The degree of regression in LV mass is independent of prosthesis type implanted.     

Should minimally invasive aortic valve replacement be restricted to primary interventions?

BACKGROUND: The role of minimally invasive aortic valve replacement in cardiac reoperations has not yet been defined. The purpose of this study is to report our experience with this technique. METHODS: Nineteen consecutive patients underwent aortic valve replacement via J-sternotomy as a reoperative cardiac procedure between 1999 and 2005. The mean age was 73.6 +/- 11.4 years. Previous cardiac operations included 12 (63.2 %) coronary artery bypass graftings, 6 (31.5 %) aortic valve replacements and 1 (5.2 %) mitral valve replacement. Mean follow-up was 23.6 +/- 19.7 months. The medical records were retrospectively analyzed. RESULTS: All procedures were successful. Mean aortic cross-clamping time and cardiopulmonary bypass time were 87.4 +/- 32.7 and 133.1 +/- 54.4 minutes, respectively. Cannulation sites were: ascending aorta (52.6 %), femoral artery (47.4 %), femoral vein (94.8 %) and right atrium (5.2 %). Myocardial protection was obtained by selective coronary osteal cold crystalloid cardioplegia and systemic cooling (mean 26.2 +/- 4 degrees C). Average intubation time was 1.5 +/- 1.4 days. Mean intensive care unit stay and postoperative hospital stay was 2.9 +/- 2.6 and 12.9 +/- 5.7 days, respectively. Median chest tube output was 550 ml. There were 4 revisions for bleeding. There were 2 late deaths and one non-incision related hospital death (5 %). This patient, who was already being treated for chronic dialysis, died on day 22 due to a cerebrovascular accident. CONCLUSIONS: Minimally invasive aortic valve replacement is feasible as a reoperative procedure. Its major advantage is avoidance of cardiac reexposure with potential damage to coronary grafts. We think this technique deserves more widespread application.     

Is ventricular repolarization heterogeneity a cause of serious ventricular tachyarrhythmias in aortic valve stenosis?

BACKGROUND: It is well known that there is a close relation between sudden cardiac death and serious ventricular tachyarrhythmias in patients with aortic valve stenosis (AS). QT dispersion (QTd) reflects the ventricular repolarization heterogeneity and has been proposed as an indicator for ventricular arrhythmias. HYPOTHESIS: This study investigated the QTd and its relevance to the clinical and echocardiographic variables. METHODS: In all, 51 patients (33 men, 18 women, mean age 56 +/- 12) with isolated AS and 51 age- and gender-matched healthy controls comprised the study group. Left ventricular mass index (LVMI) was calculated by the Devereux formula, and we used continuous-wave Doppler (n = 15) and cardiac catheterization (n = 36) for the determination of the maximum aortic valve pressure gradient (PG). RESULTS: Corrected QTd (QTcd) (89 +/- 39 vs. 49 +/- 15 ms, p < 0.001) and LVMI (176 +/- 69 g/m2 vs. 101 +/- 28 g/m2, p < 0.001) in patients with AS were significantly different from those in the control group. The group of 21 patients had a significantly greater number of 24-h mean ventricular premature beats (VPB) and mean number of couplet VT episodes than did the control group (p < 0.05). QTcd also correlated significantly well with LVMI (r = 0.58, p < 0.001), PG (r = 0.41, p = 0.003), and number of 24-h VPB (r = 0.56, p = 0.008). With respect to symptoms (e.g., angina, syncope, and dyspnea) patients without symptoms (n = 19) displayed less QTcd (71 +/- 31 vs. 100 +/- 39 ms, p = 0.007) and less LVMI (144 +/- 80 g/m2 vs. 195 +/- 57 g/m2, p = 0.01) than patients with symptoms. Statistical analysis was similar for all variables with uncorrected QTd values. CONCLUSION: We found that ventricular repolarization heterogeneity was greater in patients with AS than in controls. Our findings also showed that QTd in the patient group correlates well with LVMI, severity of AS, and PG. The present results suggest that serious ventricular arrhythmias in patients with AS may be due to spatial ventricular repolarization abnormality.     

What influences the outcome of valve replacement in critical aortic stenosis?

Even patients with severely reduced left ventricular function and critical aortic stenosis can improve notably following valve replacement.     

Does aortic valve replacement mitigate the risk of preoperative heart failure?

Congestive heart failure complicating aortic valve disease has been reported to increase the operative mortality associated with aortic valve replacement. To determine whether this adverse effect remains late after aortic valve replacement, we analyzed prospectively collected and survival data of 849 patients who underwent aortic valve replacement between 1999 and 2008. There were 243 (29%) cases of heart failure preoperatively (138 current and 105 prior). Both operative and late mortality rates (up to 10 years) were significantly higher in heart failure patients. Current congestive heart failure caused a 3-fold increase in operative mortality and an 86% increase in late mortality, whereas previous history of heart failure caused a doubling of late mortality. Preoperative heart failure still compromises early and late survival after aortic valve replacement. Surgery should be considered early in patients with aortic valve disease and deferred, when possible, in those with frank heart failure.     

Frequency of congenitally bicuspid aortic valves in patients ≥80 years of age undergoing aortic valve replacement for aortic stenosis (with or without aortic regurgitation) and implications for transcatheter aortic valve implantation

The purpose of the present report was to determine the frequency of a congenitally bicuspid aortic valve in patients ≥80 years of age old with aortic stenosis (AS) severe enough to warrant aortic valve replacement. Transcatheter aortic valve implantation (TAVI) has traditionally been reserved for patients ≥80 years of age with severe AS involving a 3-cuspid aortic valve. Traditionally, AS involving a 2-cuspid aortic valve has been a contraindication to TAVI. We examined operatively excised stenotic aortic valves in 364 patients aged ≥80 years to determine the frequency of an underlying congenitally bicuspid aortic valve. Of the 347 octogenarians and 17 nonagenarians, 78 (22%) and 3 (18%) had stenotic congenitally bicuspid aortic valves, respectively. In conclusion, because the results of TAVI are less favorable in patients with stenotic congenitally bicuspid valves than in patients with stenotic tricuspid aortic valves, proper identification of the underlying aortic valve structure is important when considering TAVI as a therapeutic procedure for AS in older patients.     

Elucidation of cardiac physiology in aortic valve replacement: what should we know?

Over the past 50 years, aortic valve surgery has achieved enormous progress towards restoring durable and physiological performance of aortic valve prostheses, physiological coronary circulation, and thus the normal structure and function of the left ventricle. Throughout the entire history of aortic valve surgery, it has been clear that interactions between surgeons and physicians have not only led to improvements in operative techniques and results, but have also facilitated a better understanding of left ventricupathophysiology underlying the surgery. Embracing genetic technology with classical cardiac physiology will create a new platform to yield a more in-depth understanding of the nature of myocardial adaptation to pressure and volume changes associated with valve disease, and myocardial responses to heart valve surgery. Ultimately, this new knowledge will have a significant impact on heart valve surgery and cardiac medicine.