Long-Term Outcomes of Bovine versus Porcine Mitral Valve Replacement: A Multicenter Analysis.

Introduction: Recent national guidelines recommending mitral valve replacement (MVR) for severe secondary mitral regurgitation have resulted in an increased utilization of mitral bioprosthesis. There is a paucity of data on how longitudinal clinical outcomes vary by prosthesis type. We examined long-term survival and risk of reoperation between patients having bovine vs. porcine MVR. Study Design. A retrospective analysis of MVR or MVR + coronary artery bypass graft (CABG) from 2001 to 2017 among seven hospitals reporting to a prospectively maintained clinical registry was conducted. The analytic cohort included 1,284 patients undergoing MVR (801 bovine and 483 porcine). Baseline comorbidities were balanced using 1 : 1 propensity score matching with 432 patients in each group. The primary end point was all-cause mortality. Secondary end points included in-hospital morbidity, 30-day mortality, length of stay, and risk of reoperation. Results: In the overall cohort, patients receiving porcine valves were more likely to have diabetes (19% bovine vs. 29% porcine; p < 0.001), COPD (20% bovine vs. 27% porcine; p=0.008), dialysis or creatinine >2 mg/dL (4% bovine vs. 7% porcine; p=0.03), and coronary artery disease (65% bovine vs. 77% porcine; p < 0.001). There was no difference in stroke, acute kidney injury, mediastinitis, pneumonia, length of stay, in-hospital morbidity, or 30-day mortality. In the overall cohort, there was a difference in long-term survival (porcine HR 1.17 (95% CI: 1.00-1.37; p=050)). However, there was no difference in reoperation (porcine HR 0.56 (95% CI: 0.23-1.32; p=0.185)). In the propensity-matched cohort, patients were matched on all baseline characteristics. There was no difference in postoperative complications or in-hospital morbidity and 30-day mortality. After 1 : 1 propensity score matching, there was no difference in long-term survival (porcine HR 0.97 (95% CI: 0.81-1.17; p=0.756)) or risk of reoperation (porcine HR 0.54 (95% CI: 0.20-1.47; p=0.225)). Conclusions: In this multicenter analysis of patients undergoing bioprosthetic MVR, there was no difference in perioperative complications and risk of reoperation of long-term survival after matching.

Remote preconditioning and major clinical complications following adult cardiovascular surgery: systematic review and meta-analysis.

BACKGROUND: A number of 'proof-of-concept' trials suggest that remote ischaemic preconditioning (RIPC) reduces surrogate markers of end-organ injury in patients undergoing major cardiovascular surgery. To date, few studies have involved hard clinical outcomes as primary end-points. METHODS: Randomised clinical trials of RIPC in major adult cardiovascular surgery were identified by a systematic review of electronic abstract databases, conference proceedings and article reference lists. Clinical end-points were extracted from trial reports. In addition, trial principal investigators provided unpublished clinical outcome data. RESULTS: In total, 23 trials of RIPC in 2200 patients undergoing major adult cardiovascular surgery were identified. RIPC did not have a significant effect on clinical end-points (death, peri-operative myocardial infarction (MI), renal failure, stroke, mesenteric ischaemia, hospital or critical care length of stay). CONCLUSION: Pooled data from pilot trials cannot confirm that RIPC has any significant effect on clinically relevant end-points. Heterogeneity in study inclusion and exclusion criteria and in the type of preconditioning stimulus limits the potential for extrapolation at present. An effort must be made to clarify the optimal preconditioning stimulus. Following this, large-scale trials in a range of patient populations are required to ascertain the role of this simple, cost-effective intervention in routine practice.

Physiological effects of nonthyroidal illness syndrome in patients after cardiac surgery.

In a prospective randomized placebo-controlled study, we assessed potential physiological effects of nonthyroidal illness syndrome (NTIS) in acute illness. Coronary artery bypass graft surgery was employed as a prospective model of acute illness and NTIS. Triiodothyronine (T(3)) or placebo was infused for 24 h after surgery, with a T(3) dose selected to maintain postoperative serum T(3) concentrations at preoperative levels. Patients were evaluated before coronary artery bypass graft and during the postoperative period. Cardiovascular function was monitored with Swan-Ganz catheter measurements and ECG. Urinary nitrogen excretion and L-[1-(13)C]leucine flux were used to evaluate protein metabolism. Serum measurements of relevant hormones, iron, and total iron-binding capacity were used to assess effects on sex steroid, growth hormone axis, and iron responses to illness. Cardiovascular function was not affected by T(3) infusion, except for a transient higher cardiac index in the T(3) group 6 h after surgery (3.04 +/- 0.12 for T(3) and 2.53 +/- 0.08 for placebo, P = 0.0016). Protein metabolism was not affected; changes in urinary nitrogen excretion and L-[1-(13)C]leucine flux were equivalent in the two groups (P = 0.35 and P = 0.95, respectively). No differences were observed in changes in testosterone, estrogens, growth hormone, insulin-like growth hormone I, iron, or total iron-binding capacity between T(3) and placebo groups. We conclude that, in the early stages of major illness, the decrease in circulating T(3) concentrations in NTIS has only a minimal transient physiological impact on cardiac function and plays no significant role in protecting against protein catabolism or modulating other endocrine responses or iron responses to illness.

Reversible uncoupling of oxidative phosphorylation at low oxygen tension.

The stoichiometry of oxidative phosphorylation at low oxygen tension (less than 3 torr; O2 less than 5 microM) has been measured in rat liver mitochondria. In a steady-state model in which respiration rate was experimentally controlled by either oxygen or substrate (succinate) limitation, flux-dependent variation in the phosphorylation efficiency (P/O ratio) of stimulated mitochondrial respiration was evaluated. P/O ratio remained constant over a wide range of respiration rates in mitochondria limited only by substrate availability. In contrast, oxygen-limited mitochondria demonstrated a continuous decline in P/O ratio as respiration was increasingly restricted. Significant differences in the two test conditions were demonstrated throughout the range of analysis. The effect of oxygen limitation on phosphorylation efficiency was shown to be completely reversed by restoring zero-order kinetics associated with high oxygen tension. These findings are discussed in regard to a proposed uncoupling of mitochondrial coupling site II at low oxygen tension arising as a consequence of energy-dissipating electron flux through the ubiquinone-cytochrome b-c1 region of the respiratory chain (complex III).

Prolactin-producing pituitary tumors: surgical therapy.

Detection of a prolactin-secreting macroadenoma of the pituitary requires neurosurgical consultation and is almost certainly best resolved by operative removal. In contrast, it is not presently clear whether surgical intervention is appropriate in the majority of patients suspected of harboring microprolactinomas, particularly in view of current uncertainties surrounding the possible antimitogenic properties of bromocryptine. The decision to recommend surgery ordinarily rests on the presumption that certain of these lesions may grow to sufficient size as to represent a permanent threat to the patient's health; other considerations include the patient's desire for fertility and the perceived risk of pregnancy in the presence of a pituitary adenoma. Assuming the patient is sufficiently reliable that we can be assured of the opportunity for regular follow-up evaluations, our group advocates a conservative posture in the majority of women in whom a microprolactinoma is suspected. In any case, it is certainly possible to reassure both the referring gynecologist and the patient that should operative intervention be indicated, the transsphenoidal approach to microprolactinomas of the pituitary is today safe and generally uncomplicated. This is due in no small measure to the contributions of such pioneering neurosurgeons as Guiot, Hardy and, of course, Cushing.

Spontaneous regression of prolactin-producing pituitary adenomas.

Two women evaluated for amenorrhea, galactorrhea, and hyperprolactinemia had radiographic changes of the sella turcica (localized erosion on trispiral tomography) suggestive of a pituitary tumor. Both patients experienced spontaneous regression of apparent prolactin-secreting adenomas with a marked decrease in the quantity of galactorrhea and a reduction of serum prolactin concentrations to the normal range. One patient noted a marked improvement of headaches and spontaneous menses resumed in the other patient.

Cerebral cortical microfluorometry at isosbestic wavelengths for correction of vascular artifact.

Microfluorometric measurements of cerebral cortical mitochondrial respiration in vivo are obscured by hemodynamic and oximetric artifacts. Isosbestic fluorometry provides appropriate correction for these vascular phenomena and permits simultaneous evaluation of mitochondrial nicotinamide adenine dinucleotide redox state, microcirculatory volume, and hemoglobin oxygenation.

Hypothalamic-pituitary function and radiographic evaluation of women with hyperprolactinemia and an "empty" sella turcica.

A primary "empty" sella may be associated with significant hypothalamic-pituitary dysfunction. This report characterizes the endocrinologic and radiographic findings in six patients with hyperprolactinemia (range 34.3 to 1,170 ng/ml) ultimately found to have an enlarged empty sella. Lateral skull x-ray films and thin-section tomograms were suggestive of pituitary tumors in all patients. Four patients underwent transphenoidal sellar exploration after pneumoencephalography (PEG) failed to demonstrate air within the sella. The inability of PEG to demonstrate an empty sella in two patients was explainable on the basis of an intact diaphragma sellae with previous transient intrasellar pathology responsible for the sellar enlargement. Dynamic hypothalamic-pituitary testing yielded no consistent pattern of response. These studies suggest that an empty sella: (1) may be associated with hyperprolactinemia, regardless of etiology, (2) is not diagnosable by dynamic hormonal testing, and (3) may be indistinguishable from a pituitary tumor by current radiographic techniques.

Traumatic anterior atlanto-occipital dislocation.

The five cases of atlanto-occipital dislocation reported in the world literature are reviewed, and four additional cases are presented, including two survivors. The pathological anatomy of this potentially catastrophic injury and its management are briefly discussed. Because immediate recognition of the atlanto-occipital dislocation is critical to proper treatment and because the neurological findings are extremely varied, a new radiographic criterion for its identification has been developed.

Brain adenosine triphosphate: decreased concentration precedes convulsions.

The concentration of adenosine triphosphate in the brain decreased before the onset of generalized convulsions in unanesthetized rats subjected to acute hypoxia or treated with hydroxylamine or pentylenetetrazole (Metrazol). As the convulsive episode continued, adenosine triphosphate decreased further. Stimulation of adenosine triphosphate production forestalled its disappearance from the brain and delayed the development of seizure activity.