Renal artery duplex ultrasound criteria for the detection of significant in-stent restenosis.

OBJECTIVES: To define velocity criteria by ultrasonography for the detection of hemodynamically significant (>60%) renal artery in-stent restenosis (ISR). BACKGROUND: The restenosis rate after renal artery stenting ranges between 10% and 20%. While duplex ultrasound criteria have been validated for native renal artery stenosis, there are no uniformly accepted validated criteria for stented renal arteries. METHODS: Vascular laboratory databases from two academic medical centers were retrospectively reviewed for patients who underwent renal artery stenting followed by duplex ultrasound evaluation and angiography (CT angiography or catheter angiography) as the gold standard. RESULTS: A cohort of 132 stented renal arteries that had angiographic comparisons was analyzed. Eighty-eight renal arteries demonstrated 0-59% stenosis while 44 renal arteries revealed 60-99% stenosis by angiography. Both the mean peak systolic velocity (PSV) and the renal artery-to-aortic ratio (RAR) were significantly higher in renal arteries with 60-99% restenosis compared with those with 0-59% restenosis (PSV: 382 cm/sec ± 128 vs. 129 cm/sec ± 62, P<0.001; RAR: 5.3 ± 2.4 vs. 2.1 ± 1.0, P <0.001). The optimal PSV and RAR cutoffs for detecting 60-99% ISR were calculated by receiver operator characteristics curve analysis. The velocity criteria that are associated with these results will be discussed. CONCLUSION: Duplex ultrasonography is an accurate technique to identify significant restenosis in stented renal arteries. The PSV and RAR cutoffs for detecting renal artery ISR are higher than those in native, unstented renal arteries. A normal duplex ultrasound after renal artery stenting virtually excludes significant restenosis.

Takotsubo cardiomyopathy followed by neurogenic stunned myocardium in the same patient: gradations of the same disease?

Takotsubo cardiomyopathy is a phenomenon of transient acute left ventricular dysfunction without obstructive coronary disease seen predominantly in postmenopausal women in the setting of acute emotional or physical stress. Neurocardiogenic injury from acute neurologic events such as intracranial bleeding can precipitate transient left ventricular dysfunction (termed 'neurogenic stunned myocardium') that may be indistinguishable from takotsubo cardiomyopathy. There is controversy about the diagnosis of takotsubo cardiomyopathy in the setting of acute neurologic disorders. We describe a case of a 67-year-old female who initially presented with takotsubo cardiomyopathy due to an acute gastrointestinal illness and 4 years later developed a recurrence in the setting of an ischemic cerebrovascular accident that was associated with more prominent EKG changes and much higher cardiac biomarker release but similar degree of left ventricular dysfunction. This case suggests that susceptibility to this disorder is likely due to patient-specific factors rather than etiology, and acute neurologic disorders should be included as precipitants of takotsubo cardiomyopathy. We also theorize that there may be patients with milder forms of stress-related cardiac injury who do not develop left ventricular dysfunction, being similar to the wide range of cardiac manifestations in patients with acute neurologic disorders. We review published literature on neurologic precipitants of takotsubo cardiomyopathy.

Lack of sensitization and equivalent post-transplant outcomes with the Novacor left ventricular assist device.

BACKGROUND: Ventricular assist devices (VADs) are increasingly used to support critically ill heart failure patients awaiting transplantation. Previous work has focused on the Thoratec Heartmate VE device, use of which is associated with pre-formed antibody production. We reviewed our cumulative experience with the Worldheart Novacor VAD as a bridge to transplantation (BTT). METHODS: From January 1989 through October 2002, 39 patients required a VAD bridge, with 26 of 39 surviving to transplantation. Antibody levels were assessed by complement-dependent cytotoxicity assay at routine intervals and expressed as panel reactive antibody (PRA) levels. Post-transplant allograft rejection, coronary vasculopathy, and survival were compared between Novacor-supported patients and non-VAD transplant recipients. RESULTS: PRA values did not significantly change after VAD implantation (12.4% +/- 11.2% vs 14.8% +/- 12.3%, p = 0.28). Survival for the BTT patients was 80.4%, 75.7%, 64.0%, 64.0%, and 64.0%, respectively, for 1, 3, 5, 7, and 10 years post-transplant, with similar results for non-BTT patients. The freedom from coronary vasculopathy was 90.2%, 90.2%, 72.2%, and 72.2%, respectively, at 1, 3, 5, and 7 years post-transplant. CONCLUSIONS: First, to our knowledge, this study is the first to examine the incidence of allosensitization after Novacor implant in detail. In contrast with previous results of work with other VAD systems, as assessed by PRA levels, Novacor patients did not become sensitized. Second, compared with 220 non-BTT patients who received transplants during a similar time frame, Novacor BTT patients had equivalent rejection profiles and survival. Finally, the incidence of transplant-associated coronary artery disease was lower than in previous reports.

Calcineurin inhibitor-associated early renal insufficiency in cardiac transplant recipients: risk factors and strategies for prevention and treatment.

Cardiac transplantation is the definitive treatment for eligible patients with end-stage cardiac failure. Techniques have evolved to reduce surgical mortality to under 5%. Immediate and subsequent long-term survival is more dependent on acute and chronic rejection and the complications of immunosuppressive therapy. Ten-year survival is greater than 50%.The success of transplantation over the last 20 years has been largely due to the advances in immunosuppression. The most notable and dramatic milestone was the introduction of cyclosporine in the early 1980s, which resulted in a significant improvement in allograft and patient survival. Cyclosporine is a peptide that inhibits the immune system by suppressing T-helper cell activation via inhibition of calcineurin, a critical intracellular enzyme. Tacrolimus has a similar (but not identical) mechanism of action, and was introduced in the 1990s. Drugs such as cyclosporine and tacrolimus, generically referred to as calcineurin inhibitors, have become the cornerstones of immunosuppressive protocols. As a group, calcineurin inhibitors have adverse effects, including neurotoxicity, hypertension, and nephrotoxicity, which complicate their use. Early renal insufficiency manifests as postoperative oliguria (<50 mL/h urine output) or rising serum creatinine levels. There are a variety of postulated causes for calcineurin inhibitor-associated early renal insufficiency including direct calcineurin inhibitor-mediated renal arteriolar vasoconstriction, increased levels of endothelin-1 (a potent vasoconstrictor), as well as decreased nitric oxide production and alterations in the kidney's ability to adjust to changes in serum tonicity. Once early renal insufficiency occurs, no single treatment has been shown to be effective. Approaches discussed in this paper include reduction in calcineurin inhibitor dosages, as well as various drugs to promote increased renal perfusion such as misoprostol and dopamine. In addition, the paper emphasizes the importance of ruling out other causes of renal insufficiency in the early postoperative period, including volume depletion, depressed cardiac output, and mechanical obstruction to urine flow. Given that there is no highly efficacious treatment for this syndrome, ways to avoid its occurrence are desirable. One paper is referenced that suggests that avoidance of rapid changes in tacrolimus level during the first three days of therapy is associated with a low occurrence of early renal insufficiency.

"One size fits all": immunosuppression in cardiac transplantation.

Approximately 20 years have passed since the introduction of cyclosporine-based triple therapy for heart transplant recipients. The major thrust of research has been the "middle-drug" between cyclosporine and steroids, and recent efforts have been directed towards newer antibody preparations to induce rapid immunosuppression post-transplant. However, little effort has been paid to attempts to reduce and tailor immunosuppression to specific patients. This paper describes previous work on the individualized dosing of tacrolimus, including patients who are maintained on monotherapy after heart transplantation with tacrolimus alone. The authors conclude that future efforts need to be directed towards individualizing immunosuppression rather than adopting "one-size-fits-all" institutional protocols.