Systematic off-pump coronary artery revascularization in multivessel disease: Experience of three hundred cases

AbstractObjective: We sought to report our recent experience with off-pump coronary artery revascularization in multivessel disease. Methods: Between October 1996 and December 1998, 300 off-pump beating heart operations were performed at the Montreal Heart Institute by a single surgeon, representing 94% of all procedures undertaken during this same time frame (97% for 1998). This cohort of patients was compared with 1870 patients operated on with cardiopulmonary bypass from 1995 to 1996. Results: Mean age, sex distribution, and preoperative risk factors were comparable for the two groups. On average, 2.92 ± 0.8 and 2.84 ± 0.6 grafts per patient were completed in the beating heart and cardiopulmonary bypass groups, respectively. A majority of patients (70%) had either a triple or quadruple bypass. Coronary anastomoses were achieved with myocardial mechanical stabilization and heart “verticalization.” Ischemic time was shorter in the beating heart group (29.8 ± 0.9 vs 45 ± 0.4 minutes, P < .05). Similarly, the need for transfusion was significantly less in the beating heart group (beating heart operations, 34%; cardiopulmonary bypass, 66%; P < .005). Reduced use of postoperative intra-aortic counterpulsation, as well as a lower rise in creatine kinase MB isoenzyme, was observed in the beating heart group. Operative mortality rates (beating heart operations, 1.3%; cardiopulmonary bypass, 2%) and perioperative myocardial infarction (beating heart operations, 3.6%; cardiopulmonary bypass, 4.2%) were comparable for the two groups. Conclusion: In a majority of patients, off-pump complete coronary artery revascularization is an acceptable alternative to conventional operations, yielding good results given progressive experience, rigorous technique, and adequate coronary artery stabilization. (J Thorac Cardiovasc Surg 2000;119:221-9

Influence of Age on Long-Term Cardiac Mortality and Morbidity after Off-Pump Coronary Artery Bypass Surgery

editorial reviewedBackground: Age at the time of surgery is a major determinant in long-term survival. Its specific significance on long-term cardiac mortality and major adverse cardiac events (MACE) are poorly understood. Aims of the study: To compare long-term cardiac outcome after off-pump coronary artery bypass (OPCAB) surgery according to different age groups. Methods: We used our prospective data base of 1000 consecutive OPCAB patients (777 men and 223 women) operated between September 1996 and March 2004 representing 98% of all coronary revascularizations during the same time frame. Follow-up was complete in 97% of the cohort. Average folow-up was 68432 months. Patients were divided in 3 groups: Group 1: s 50 years, Group 2: 50-65 years, and Group 3: 2 65 years of age. Results: Highest men/women ratio was in Group 2. Prevalence of peripheral (PVD), cerebral (CVD) vascular disease, and diabetes was higher in Group 3. Emergencies were also more infrequent in the oldest group. Thirty-day mortality and perioperative myocardial infarction (M) were similar in all groups. Group 3 had more grafts done and prevalence of postoperative atrial fibrillation (AF), renal insufficiency, transfusion need was higher. Adjusted 10-year cardiac survival was decreased only in Group 3 (HR=2.3). Adjusted major adverse cardiac events free survival (p=0.55) were also comparable in the 3 cohorts. Conclusion: Age at the time of surgery was a significant determinant of long-term cardiac mortality after OPCAB surgery but did not influence the occurrence of major adverse cardiac events

Effects of in vitro potassium on ammoniagenesis in rat and canine kidney tissue

Effects of in vitro potassium on ammoniagenesis in rat and canine kidney tissue. Decreased ammonium (NH4+) excretion is associated with hyperkalemia. To determine if potassium could directly influence renal ammonia production, we investigated ammoniagenesis by rat and canine renal cortical tissues in vitro at different potassium concentrations. Renal tissue from normal and acidotic rats and normal dogs incubated in glutamine, lactate, and 7 to 10mEq/liters of potassium or 25mEq/liters of potassium produced significantly less ammonia than slices incubating in glutamine, lactate, and 4 to 5mEq of potassium. Glutamate accumulation, which follows glutamine deamidation, did not decrease and even increased at 25mEq/liters of potassium. With glutamine as the sole substrate, decreased ammoniagenesis was seen only at higher potassium concentrations (> 16mEq/liters) than when lactate was also present. The depression to glutamine ammoniagenesis by high concentrations of potassium was partially obliterated in an anaerobic environment. When glutamate replaced glutamine as the precursor, renal ammonia produced by slices in 7 and 25mEq/liters was again significantly lower than by slices incubating in 4mEq/liters. We blocked glutamine synthesis by rat kidney slices with dl-methionine dl-sulfoximine when glutamate was the renal ammonia precursor. This essentially allows glutamate deamination to produce ammonia. Potassium depressed glutamate deamination significantly at 7mEq/liters (↓ 13%) and at 25mEq/liters of potassium (↓ 35%) as compared to 4mEq/liters. The above findings are consistent with a major depressive effect of in vitro potassium on glutamate deamination in rat and canine kidneys. Other evidence, especially from rat tissue studies, suggests that potassium also may affect glutamine deamination directly. Rat kidney slices incubating in the high potassium medium of 7mEq/liter or greater also consumed less oxygen in the presence of glutamine (P < 0.01), oxidatively decarboxylated less glutamine (P < 0.02) and produced less glucose from glutamine (P < 0.01).Effet du potassium in vitro sur l'ammoniogenèse dans tissu rénal de rat et de chien. Une diminution de l'excrétion d'ammoniaque (NH4+) est associée à l'hyperkaliémie. Afin de déterminer si le potassium peut influencer directement la production rénale d'ammoniac, nous avons étudié l'ammoniogenèse dans le tissu rénal cortical de rat et de chien in vitro à différentes concentrations de potassium. Du tissu rénal provenant de rats normaux et en acidose et de chiens normaux incubés dans de la glutamine, du lactate, et 7 à 10mEq/litres de potassium ou 25mEq/litres de potassium produit significativement moins d'ammoniac que des tranches incubées dans de la glutamine, du lactate, et 4 à 5mEq/litres de potassium. L'accumulation de glutamate, consécutive à la deamination de la glutamine, n'a pas diminué et même a augmenté à 25mEq/litres de potassium. Avec la glutamine comme seul substrat, la diminution de l'ammoniogenèse n'a été observée qu'à des concentrations de potassium supérieures (> 16mEq/litres) à celle nécessaire quand le lactate est présent. La dépression de l'ammoniogenèse due à la glutamine au moyen de concentrations élevées de potassium est partiellement abolie par un environnement anaérobique. Quand la glutamine est remplacée par du glutamate, le rénale d'ammoniac produit par des tranches dans des milieux à 7mEq/litres et 25mEq/litres est là encore significativement inférieur à celui produit par des tranches incubées dans un milieu à 4mEq/litres. Nous avons bloqué la synthèse de glutamine dans les tranches de rein de rat au moyen de la dl-méthionine dl-sulfoximine quand le glutamate était le précurseur de rénale d'ammoniac. Ceci permet à la déamination du glutamate de produire de l'ammoniac. Potassium diminue significativement la déamination du glutamate à 7mEq/litres (diminution de 13%), et à 25mEq/litres (diminution de 35%) par comparaison avec les valeurs obtenues à 4mEq/litres. Ces constatations sont compatibles avec un effet dépresseur majeur du potassium in vitro sur la déamination du glutamate dans les reins de rat et de chien. D'autres arguments, tirés essentiellement des études sur le tissu de rat, suggèrent que le potassium peut aussi affecter la déamination du glutamate directement. Des tranches de rein de rat incubées dans un milieu riche en potassium (7mEq/litres ou plus) consomment moins d'oxygène en présence de glutamine (P < 0,01), décarboxylent moins de glutamine par oxydation (P < 0,02) et produisent moins de glucose à partir de la glutamine (P < 0,01)

SN 2019ehk: A Double-peaked Ca-rich Transient with Luminous X-Ray Emission and Shock-ionized Spectral Features

We present panchromatic observations and modeling of the Calcium-rich supernova (SN) 2019ehk in the star-forming galaxy M100 (d ≈ 16.2 Mpc) starting 10 hr after explosion and continuing for ~300 days. SN 2019ehk shows a double-peaked optical light curve peaking at t = 3 and 15 days. The first peak is coincident with luminous, rapidly decaying Swift-XRT–discovered X-ray emission (L_x ≈ 10⁴¹ erg s⁻¹ at 3 days; L_x ∝ t⁻³), and a Shane/Kast spectral detection of narrow Hα and He II emission lines (v ≈ 500 km s⁻¹) originating from pre-existent circumstellar material (CSM). We attribute this phenomenology to radiation from shock interaction with extended, dense material surrounding the progenitor star at r (0.1–1) × 10¹⁷ cm. The photometric and spectroscopic properties during the second light-curve peak are consistent with those of Ca-rich transients (rise-time of t_r = 13.4 ± 0.210 days and a peak B-band magnitude of M_B = −15.1 ± 0.200 mag). We find that SN 2019ehk synthesized (3.1 ± 0.11) × 10⁻² M_⊙ of ⁵⁶Ni and ejected M_(ej) = (0.72 ± 0.040) M⊙ total with a kinetic energy E_k = (1.8 ± 0.10) × 10⁵⁰ erg. Finally, deep HST pre-explosion imaging at the SN site constrains the parameter space of viable stellar progenitors to massive stars in the lowest mass bin (~10 M_⊙) in binaries that lost most of their He envelope or white dwarfs (WDs). The explosion and environment properties of SN 2019ehk further restrict the potential WD progenitor systems to low-mass hybrid HeCO WD+CO WD binaries

Multi-messenger observations of a binary neutron star merger

On 2017 August 17 a binary neutron star coalescence candidate (later designated GW170817) with merger time 12:41:04 UTC was observed through gravitational waves by the Advanced LIGO and Advanced Virgo detectors. The Fermi Gamma-ray Burst Monitor independently detected a gamma-ray burst (GRB 170817A) with a time delay of ~1.7 s with respect to the merger time. From the gravitational-wave signal, the source was initially localized to a sky region of 31 deg2 at a luminosity distance of 40+8-8 Mpc and with component masses consistent with neutron stars. The component masses were later measured to be in the range 0.86 to 2.26 Mo. An extensive observing campaign was launched across the electromagnetic spectrum leading to the discovery of a bright optical transient (SSS17a, now with the IAU identification of AT 2017gfo) in NGC 4993 (at ~40 Mpc) less than 11 hours after the merger by the One- Meter, Two Hemisphere (1M2H) team using the 1 m Swope Telescope. The optical transient was independently detected by multiple teams within an hour. Subsequent observations targeted the object and its environment. Early ultraviolet observations revealed a blue transient that faded within 48 hours. Optical and infrared observations showed a redward evolution over ~10 days. Following early non-detections, X-ray and radio emission were discovered at the transient’s position ~9 and ~16 days, respectively, after the merger. Both the X-ray and radio emission likely arise from a physical process that is distinct from the one that generates the UV/optical/near-infrared emission. No ultra-high-energy gamma-rays and no neutrino candidates consistent with the source were found in follow-up searches. These observations support the hypothesis that GW170817 was produced by the merger of two neutron stars in NGC4993 followed by a short gamma-ray burst (GRB 170817A) and a kilonova/macronova powered by the radioactive decay of r-process nuclei synthesized in the ejecta

Multi-messenger Observations of a Binary Neutron Star Merger

On 2017 August 17 a binary neutron star coalescence candidate (later designated GW170817) with merger time 12:41:04 UTC was observed through gravitational waves by the Advanced LIGO and Advanced Virgo detectors. The Fermi Gamma-ray Burst Monitor independently detected a gamma-ray burst (GRB 170817A) with a time delay of ∼ 1.7 {{s}} with respect to the merger time. From the gravitational-wave signal, the source was initially localized to a sky region of 31 deg2 at a luminosity distance of {40}-8+8 Mpc and with component masses consistent with neutron stars. The component masses were later measured to be in the range 0.86 to 2.26 {M}ȯ . An extensive observing campaign was launched across the electromagnetic spectrum leading to the discovery of a bright optical transient (SSS17a, now with the IAU identification of AT 2017gfo) in NGC 4993 (at ∼ 40 {{Mpc}}) less than 11 hours after the merger by the One-Meter, Two Hemisphere (1M2H) team using the 1 m Swope Telescope. The optical transient was independently detected by multiple teams within an hour. Subsequent observations targeted the object and its environment. Early ultraviolet observations revealed a blue transient that faded within 48 hours. Optical and infrared observations showed a redward evolution over ∼10 days. Following early non-detections, X-ray and radio emission were discovered at the transient’s position ∼ 9 and ∼ 16 days, respectively, after the merger. Both the X-ray and radio emission likely arise from a physical process that is distinct from the one that generates the UV/optical/near-infrared emission. No ultra-high-energy gamma-rays and no neutrino candidates consistent with the source were found in follow-up searches. These observations support the hypothesis that GW170817 was produced by the merger of two neutron stars in NGC 4993 followed by a short gamma-ray burst (GRB 170817A) and a kilonova/macronova powered by the radioactive decay of r-process nuclei synthesized in the ejecta.</p