Relaxation Phenomena in a System of Two Harmonic Oscillators

We study the process by which quantum correlations are created when an interaction Hamiltonian is repeatedly applied to a system of two harmonic oscillators for some characteristic time interval. We show that, for the case where the oscillator frequencies are equal, the initial Maxwell-Boltzmann distributions of the uncoupled parts evolve to a new equilibrium Maxwell-Boltzmann distribution through a series of transient Maxwell-Boltzmann distributions. Further, we discuss why the equilibrium reached when the two oscillator frequencies are unequal, is not a thermal one. All the calculations are exact and the results are obtained through an iterative process, without using perturbation theory.Comment: 22 pages, 6 Figures, Added contents, to appear in PR

Atrial Dysfunction in Significant Atrial Functional Mitral Regurgitation: Phenotypes and Prognostic Implications

Background: Atrial functional mitral regurgitation (AFMR) is associated with increased morbidity and mortality. Left atrial (LA) size and function in AFMR are poorly characterized. We aimed to assess LA function by reservoir strain (LASr) and estimated reservoir work (LAWr) and their impact on outcome in AFMR. Methods: Consecutive patients at our institution between 2001 and 2019 and with significant (moderate or greater) AFMR were examined. LAWr was estimated as LASr×LA reservoir volume, and patients were grouped by median LASr and LAWr. Outcomes were all-cause death or heart failure hospitalizations. Results: Five hundred fifteen AFMR patients were followed up for 5 (1–17) years. Patients had previously documented atrial fibrillation (AF; 37%), heart failure with preserved ejection fraction (HFpEF) without AF (24%), or both (HFpEF+AF, 39%). LA volume was largest in AF, while LA function parameters were most impaired in the combined HFpEF+AF group. During follow-up, patients with low LASr or LAWr had higher risk of death (P<0.001) and heart failure hospitalization (P<0.05). In Cox regression analyses, low LASr and LAWr, but not LA volume or left ventricular function, were associated with a higher risk of death (LASr: hazard ratio, 2.3 [95% CI, 1.6–3.5]; LAWr: hazard ratio, 3.4 [95% CI, 2.4–4.9]; both P<0.001) after adjustment for clinical and echocardiographic confounders. Low LASr and LAWr were strongest associated with death in HFpEF and HFpEF+AF. Conclusions: LA reservoir function but not LA size is a robust predictor of outcome in significant AFMR. This provides mechanistic insights into the interplay of functional versus geometric LA changes in AFMR.publishedVersio

Building a successful minimally invasive mitral valve repair program before introducing the robotic approach: The Massachusetts General Hospital experience

BackgroundPatients with mitral valve prolapse (MVP) requiring surgical repair (MVr) are increasingly operated using minimally invasive strategies. Skill acquisition may be facilitated by a dedicated MVr program. We present here our institutional experience in establishing minimally invasive MVr (starting in 2014), laying the foundation to introduce robotic MVr.MethodsWe reviewed all patients that had undergone MVr for MVP via sternotomy or mini-thoracotomy between January 2013 and December 2020 at our institution. In addition, all cases of robotic MVr between January 2021 and August 2022 were analyzed. Case complexity, repair techniques, and outcomes are presented for the conventional sternotomy, right mini-thoracotomy and robotic approaches. A subgroup analysis comparing only isolated MVr cases via sternotomy vs. right mini-thoracotomy was conducted using propensity score matching.ResultsBetween 2013 and 2020, 799 patients were operated for native MVP at our institution, of which 761 (95.2%) received planned MVr (263 [34.6%] via mini-thoracotomy) and 38 (4.8%) received planned MV replacement. With increasing proportions of minimally invasive procedures (2014: 14.8%, 2020: 46.5%), we observed a continuous growth in overall institutional volume of MVP (n = 69 in 2013; n = 127 in 2020) and markedly improved institutional rates of successful MVr, with 95.4% in 2013 vs. 99.2% in 2020. Over this period, a higher complexity of cases were treated minimally-invasively and increased use of neochord implantation ± limited leaflet resection was observed. Patients operated minimally invasively had longer aortic cross-clamp times (94 vs. 88 min, p = 0.001) but shorter ventilation times (4.4 vs. 4.8 h, p = 0.002) and hospital stays (5 vs. 6 days, p &lt; 0.001) than those operated via sternotomy, with no significant differences in other outcome variables. A total of 16 patients underwent robotically assisted MVr with successful repair in all cases.ConclusionA focused approach towards minimally invasive MVr has transformed the overall MVr strategy (incision; repair techniques) at our institution, leading to a growth in MVr volume and improved repair rates without significant complications. On this foundation, robotic MVr was first introduced at our institution in 2021 with excellent outcomes. This emphasizes the importance of building a competent team to perform these challenging operations, especially during the initial learning curve

Minimally Invasive Coronary Revascularisation Surgery: A Focused Review of the Available Literature

Minimally invasive coronary revascularisation was originally developed in the mid 1990s as minimally invasive direct coronary artery bypass (MIDCAB) grafting is a less invasive approach compared to conventional coronary artery bypass grafting (CABG) to address targets in the left anterior descending coronary artery (LAD). Since then, MIDCAB has evolved with the adoption of a robotic platform and the possibility to perform multivessel bypass procedures. Minimally invasive coronary revascularisation surgery also allows for a combination between the benefits of CABG and percutaneous coronary interventions for non-LAD lesions – a hybrid approach. Hybrid coronary revascularisation results in fewer blood transfusions, shorter hospital stay, decreased ventilation times and patients return to work sooner when compared to conventional CABG. This article reviews the available literature, describes standard approaches and considers topics, such as limited access procedures, indications and patient selection, diagnostics and imaging, techniques, anastomotic devices, hybrid coronary revascularisation and outcome analysis

Right anterolateral thoracotomy vs. median sternotomy as access ways for isolated surgical aortic valve replacement

Minimally invasive approaches to isolated aortic valve replacement (AVR) continue to gain popularity and have shown excellent results regarding morbidity and mortality. Upper hemisternotomy is the more widespread method. The right anterolateral thoracotomy (RALT) provides an alternative approach that is potentially even less invasive. This study compares the peri- and postoperative outcomes of patients that underwent isolated aortic valve replacement through RALT or MS. To increase comparability of the two groups, a propensity score matching was conducted. Propensity score matching produced 85 matched pairs with balanced preoperative characteristics. Procedure times were significantly shorter in the RALT group (RALT 163 min, MS 179 min, median difference -13 min [IQR -25 - -0.5], p = 0.039), cardiopulmonary bypass times longer (RALT 105 min, MS 87 min, median difference -17 min [IQR -2 - -26], p < 0.001), aortic cross clamp times comparable (RALT 65 min, MS 67 min, median difference 1.5 min [IQR -3.5 – 6.5], p = 0.578) and ventilation times significantly shorter (RALT 448, MS 774.5 min, median difference -259 min [-390 - -122.5], p < 0.001). The RALT-group hat lower rates of platelet transfusions (RALT 3.5%, MS 15.29%, OR 0.23 [95%-CI 0.04 – 0.84], p = 0.021) and postoperative pneumonia (RALT 1.18%, MS 11.76%, OR 0.01 [95%-CI 0.002 – 0.7], p = 0.012). RALT patients were hospitalized significantly shorter (RALT 12, MS 14 days, median difference -2.5 days [IQR -4.5 - -1], p = 0.005). There were no significant differences regarding 30-day- and 1-year-mortality (p = 1), postoperative stroke (p = 1), postoperative atrial fibrillation (p = 0.119) or postoperative creatinine levels (p = 0.418). In conclusion, this retrospective study found RALT to be a comparably safe approach to surgical aortic valve replacement as MS. Prosthesis function and survival rates were excellent. While CPB times were longer, there was no increase of peri- and postoperative complications in the examined RALT-cohort. Regarding postoperative regeneration, RALT even showed clear advantages compared to MS: mechanical ventilation times were shorter, rates of postoperative pneumonia lower and patients were discharged from the hospital sooner.Minimalinvasive chirurgische Zugangswege für den isolierten Aortenklappenersatz (AKE) gewinnen an Beliebtheit und haben bisher bezüglich postoperativer Morbidität und Mortalität exzellente Ergebnisse gezeigt. Weiter verbreitet ist die obere Hemisternotomie. Die rechte anterolaterale Thorakotomie (RALT) bietet einen alternativen Ansatz, der potentiell noch weniger invasiv ist. Diese Studie vergleicht die peri- und postoperativen Ergebnisse von Patient*innen, die sich einem RALT-AKE unterzogen hatten mit solchen, die einen konventionellen AKE über mediane Sternotomie (MS) erhalten hatten. Zur besseren Vergleichbarkeit der beiden Patientengruppen wurde ein Propensity-Score-Matching durchgeführt. Es ergaben sich dadurch 85 Patientenpaare mit balancierten präoperativen Charakteristika. Die Operationszeiten waren in der RALT-Gruppe signifikant kürzer (RALT 163 min, MS 179 min, mediane Differenz -13 min [IQR -25 - -0,5], p = 0,039), die Herz-Lungen- Maschinen-Zeiten signifikant länger (RALT 105 min, MS 87 min, mediane Differenz -17 min [IQR -2 - -26], p = <0,001), die Aortenklemmzeiten vergleichbar (RALT 65 min, MS 67 min, mediane Differenz 1,5 min [IQR -3,5 - 6,5], p = 0,578) und die Beatmungszeiten signifikant kürzer (RALT 448 min, MS 774,5 min, median difference -259 min [-390 - -122,5], p = <0,001). Die RALT-Kohorte zeigte niedrigere Raten von Thrombozytentransfusionen (RALT 3,5%, MS 15,29%, OR 0,23 [95%-KI 0,04 - 0,84], p = 0,021) und postoperativen Pneumonien (RALT 1,18%, MS 11,76%, OR 0,01 [95%-KI 0,002 - 0,7], p = 0,012). RALT-Patient*innen lagen signifikant kürzer im Krankenhaus (RALT 12, MS 14 Tage, mediane Differenz -2,5 Tage [IQR -4,5 - -1], p = 0,005). Es gab keine signifikanten Unterschiede bezüglich 30-Tages- und Ein-Jahres-Mortalität (p = 1), postoperativen Schlaganfällen (p = 1), postoperativem Vorhofflimmern (p = 0,119) oder postoperativem Serum-Kreatinin (p = 0,418). Insgesamt konnte diese retrospektive Analyse zeigen, dass RALT einen ebenso sicheren Zugangsweg für den chirurgischen Aortenklappenersatz darstellt wie die MS. Prothesenfunktion und Überlebensraten waren exzellent. Die längeren Herz-Lungen-Maschinen-Zeiten führten in der untersuchten Kohorte zu keiner signifikanten Zunahme von peri- oder postoperativen Komplikationen. Der RALT-AKE zeigte in Bezug auf die postoperative Regeneration sogar deutliche Vorteile gegenüber dem MS-AKE: Die mechanischen Beatmungszeiten waren kürzer, die Rate an postoperativen Pneumonien niedriger und die Patient*innen wurden früher aus dem Krankenhaus entlassen

Surgical treatment of outflow graft kinking complicated by external obstruction with a fibrin mass in a patient with LVAD

Background Outflow graft (OG) obstruction is a dangerous complication that may occur for various reasons after left ventricular assist device (LVAD) implantation. Case Summary We describe the case of a 51‐year‐old patient on LVAD support who developed significant OG kinking and external OG obstruction due to a fibrin mass causing severe stenosis. Both the OG kinking and external obstruction were eliminated via a left lateral thoracotomy.ISSN:0886-0440ISSN:1540-819

The Feasibility of Less-Invasive Bentall Surgery: A Real-World Analysis

Objective: Minimally invasive approaches are being used increasingly in cardiac surgery and applied in a wider range of operations, including complex aortic procedures. The aim of this study was to examine the safety and feasibility of a partial upper sternotomy approach for isolated elective aortic root replacement (a modified Bentall procedure). Methods: We performed a retrospective analysis of 768 consecutive patients who had undergone isolated Bentall surgery between January 2000 and January 2021 at our institution, with the exclusion of re-operations, endocarditis, acute aortic dissections, and root replacement with major concomitant procedures such as multi-valve or coronary bypass surgery. A total of 98 patients were operated on via partial sternotomy (PS) and were matched 2:1 to 196 patients operated on via full sternotomy (FS). Results: The procedure time was 12 min longer in the PS group (205 min vs. 192.5 min in the FS group, p = 0.002), however, cardiopulmonary bypass and aortic cross-clamp times were comparable between groups. Eight PS-procedures were converted to full sternotomy, predominantly for bleeding complications (n = 6). Re-exploration for acute bleeding was necessary in 11% of the PS group and 4.1% of the FS group (p = 0.02). Five FS patients and none in the PS group required emergency coronary bypass grafting for postoperative coronary obstruction (p = 0.2). PS patients were hospitalized for a significantly shorter period (9.5 days vs. 10.5 days in the FS group, respectively). There were no significant differences regarding in-hospital (p = 0.4) and mid-term mortality (p = 0.73), as well as for other perioperative complications. Conclusions: Performing Bentall operations via partial upper sternotomy is associated with similar perfusion and cross-clamp times, as well as overall mortality, when compared to a full sternotomy approach. A low threshold for conversion to full sternotomy should be accepted if limited access proves insufficient for the handling of intraoperative complications, particularly bleeding

Minimally invasive surgical aortic valve replacement: The RALT approach

Less-invasive techniques for cardiothoracic surgical procedures are designed to limit surgical trauma, but the technical requirements and preoperative planning are more demanding than those for conventional sternotomy. Patient selection, interdisciplinary collaboration, and surgical skills are key factors for procedural success. Aortic valve replacement is frequently performed through an upper hemisternotomy, but the right anterior minithoracotomy represents an even less traumatic, technical advancement. Preoperative assessment of the ascending aorta in relation to the sternum is mandatory to select patients and the intercostal access site. This description of the surgical technique focuses on the specific procedural details including the obligatory planning with computed tomography and our cannulation strategy. We also sought to define the anatomical ascending aorta-sternal relationship, as it is of utmost importance in preoperative computed tomographic planning.ISSN:0886-0440ISSN:1540-819

Table1_Building a successful minimally invasive mitral valve repair program before introducing the robotic approach: The Massachusetts General Hospital experience.docx

BackgroundPatients with mitral valve prolapse (MVP) requiring surgical repair (MVr) are increasingly operated using minimally invasive strategies. Skill acquisition may be facilitated by a dedicated MVr program. We present here our institutional experience in establishing minimally invasive MVr (starting in 2014), laying the foundation to introduce robotic MVr.MethodsWe reviewed all patients that had undergone MVr for MVP via sternotomy or mini-thoracotomy between January 2013 and December 2020 at our institution. In addition, all cases of robotic MVr between January 2021 and August 2022 were analyzed. Case complexity, repair techniques, and outcomes are presented for the conventional sternotomy, right mini-thoracotomy and robotic approaches. A subgroup analysis comparing only isolated MVr cases via sternotomy vs. right mini-thoracotomy was conducted using propensity score matching.ResultsBetween 2013 and 2020, 799 patients were operated for native MVP at our institution, of which 761 (95.2%) received planned MVr (263 [34.6%] via mini-thoracotomy) and 38 (4.8%) received planned MV replacement. With increasing proportions of minimally invasive procedures (2014: 14.8%, 2020: 46.5%), we observed a continuous growth in overall institutional volume of MVP (n = 69 in 2013; n = 127 in 2020) and markedly improved institutional rates of successful MVr, with 95.4% in 2013 vs. 99.2% in 2020. Over this period, a higher complexity of cases were treated minimally-invasively and increased use of neochord implantation ± limited leaflet resection was observed. Patients operated minimally invasively had longer aortic cross-clamp times (94 vs. 88 min, p = 0.001) but shorter ventilation times (4.4 vs. 4.8 h, p = 0.002) and hospital stays (5 vs. 6 days, p ConclusionA focused approach towards minimally invasive MVr has transformed the overall MVr strategy (incision; repair techniques) at our institution, leading to a growth in MVr volume and improved repair rates without significant complications. On this foundation, robotic MVr was first introduced at our institution in 2021 with excellent outcomes. This emphasizes the importance of building a competent team to perform these challenging operations, especially during the initial learning curve.</p

Image1_Building a successful minimally invasive mitral valve repair program before introducing the robotic approach: The Massachusetts General Hospital experience.jpeg

BackgroundPatients with mitral valve prolapse (MVP) requiring surgical repair (MVr) are increasingly operated using minimally invasive strategies. Skill acquisition may be facilitated by a dedicated MVr program. We present here our institutional experience in establishing minimally invasive MVr (starting in 2014), laying the foundation to introduce robotic MVr.MethodsWe reviewed all patients that had undergone MVr for MVP via sternotomy or mini-thoracotomy between January 2013 and December 2020 at our institution. In addition, all cases of robotic MVr between January 2021 and August 2022 were analyzed. Case complexity, repair techniques, and outcomes are presented for the conventional sternotomy, right mini-thoracotomy and robotic approaches. A subgroup analysis comparing only isolated MVr cases via sternotomy vs. right mini-thoracotomy was conducted using propensity score matching.ResultsBetween 2013 and 2020, 799 patients were operated for native MVP at our institution, of which 761 (95.2%) received planned MVr (263 [34.6%] via mini-thoracotomy) and 38 (4.8%) received planned MV replacement. With increasing proportions of minimally invasive procedures (2014: 14.8%, 2020: 46.5%), we observed a continuous growth in overall institutional volume of MVP (n = 69 in 2013; n = 127 in 2020) and markedly improved institutional rates of successful MVr, with 95.4% in 2013 vs. 99.2% in 2020. Over this period, a higher complexity of cases were treated minimally-invasively and increased use of neochord implantation ± limited leaflet resection was observed. Patients operated minimally invasively had longer aortic cross-clamp times (94 vs. 88 min, p = 0.001) but shorter ventilation times (4.4 vs. 4.8 h, p = 0.002) and hospital stays (5 vs. 6 days, p ConclusionA focused approach towards minimally invasive MVr has transformed the overall MVr strategy (incision; repair techniques) at our institution, leading to a growth in MVr volume and improved repair rates without significant complications. On this foundation, robotic MVr was first introduced at our institution in 2021 with excellent outcomes. This emphasizes the importance of building a competent team to perform these challenging operations, especially during the initial learning curve.</p