Noncardiac surgery in long-term implantable left ventricular assist-device recipients.

OBJECTIVE: The authors describe their experience with left ventricular assist-device (LVAD) recipients undergoing noncardiac surgery and delineate surgical, anesthetic, and logistic factors important in the successful intraoperative management of these patients. SUMMARY BACKGROUND DATA: Left ventricular assist-devices have become part of the armamentarium in the treatment of end-stage heart failure. As the numbers of patients chronically supported with long-term implantable devices grows, general surgical problems that are commonly seen in other hospitalized patients are becoming manifest. Of particular interest is the intraoperative management of patients undergoing elective noncardiac surgical procedures. METHODS: The anesthesia records and clinical charts were reviewed for eight ventricular assist-device recipients undergoing general surgical procedures between August 1, 1990 and August 31, 1994. RESULTS: A total of 12 procedures were performed in 6 men and 2 women averaging 52.7 years of age. Mean time elapsed from device implantation to operation was 68 +/- 35 days. Conventional inhalational and intravenous anesthetic techniques were well tolerated in these patients undergoing diverse surgical procedures. No perioperative mortality was observed. Five of eight patients went on to successful cardiac transplantation. CONCLUSIONS: Hemodynamic recovery after LVAD insertion has defined a new group of patients who develop noncardiac surgical problems often seen in other critically ill patients. Recognition of the unique potential problems that the LVAD recipient may encounter in the perioperative period--in particular patient positioning, device limitations, and fluid and inotropic management--will ensure an optimal surgical outcome for LVAD recipients undergoing noncardiac surgery.     

Changes in snoring characteristics after 30 days of nasal continuous positive airway pressure in patients with non-apnoeic snoring: a controlled trial.

BACKGROUND--A study was performed to evaluate the effect of discontinuation of nasal continuous positive airway pressure (NCPAP) treatment on snoring characteristics. METHODS--Eighteen non-apnoeic snoring subjects were randomly allocated to either a no treatment control group or an NCPAP treatment group. The control group was studied twice (baseline and day 30 of follow up). In the NCPAP group the level of NCPAP that abolished snoring was determined and part abolished snoring was determined and patients were placed on NCPAP every night for one month. A sleep study was performed on the first night without NCPAP after completing 30 days of treatment (follow up 1). A fourth polysomnographic study was performed 8-10 days after NCPAP was stopped (follow up 2) in six subjects. RESULTS--In both groups total sleep time (TST) and sleep architecture remained unchanged at the different visits. Baseline snoring characteristics in the two groups were similar. In the control group the mean (SE) number of snoring episodes/hour of sleep (snoring index) and the percentage of TST > 60 decibels (dB) were 380 (36)/h and 11.1 (2.0)% TST respectively at baseline, and was unchanged at follow up. In the NCPAP group the snoring index decreased from 387 (50)/h to 320 (57)/h after NCPAP therapy, but the % TSTS > 60 dB decreased from 10.3 (1.8)% to 7.4 (1.5)%. The snoring index and intensity returned to baseline values at follow up 2 (374 (74)/h, 9.8 (2.1)% TST). Changes in snoring characteristics could not be explained by changes in body position between the different sleep studies. CONCLUSIONS--NCPAP improves snoring but this effect is lost soon after stopping treatment.     

Vasodepressor reactions after orthotopic cardiac transplantation: Relationship to reinnervation status

Ventricular vagal nerve endings are thought to trigger vasodepressor syncope. Reports of vasodepressor reactions associated with donor bradycardia after cardiac transplantation have led to speculation that vagal reinnervation occurs. We assessed reinnervation status in seven patients 23–36 months (median 24 months) post-transplantation. Heart rate responses to vagal manoeuvres (respiration, Valsalva) and sympathetic stimuli (exercise and injection of tyramine into the coronary artery supplying the sinus node) were measured. All patients underwent 60 min of 60° head-up tilt with foot plate support. During tilt four of the seven had vasodepressor reactions with a fall in mean arterial pressure of 20–90 mmHg. During vasodepression two patients had falls in donor heart rate of 13 and 40% relative to peak heart rate during tilt. These two patients had evidence of functional sympathetic reinnervation. By contrast the two patients without donor bradycardia during vasodepression had only limited or no evidence of sympathetic reinnervation. No patient had consistent evidence of parasympathetic reinnervation as judged by the heart rate response to vagal manoeuvres. Headup tilt can thus produce vasodepressor reactions with donor bradycardia after cardiac transplantation in the absence of consistent evidence of vagal reinnervation. Left ventricular nerve endings may not be the only mediators of tilt-induced vasodepressor reactions in man. Donor bradycardia during vasodepression may reflect sympathetic withdrawal and not vagal reinnervation.     

Empowering practice nurses in the follow-up of patients with established heart disease: lessons from patients' experiences

This paper reports on the views of patients with established heart disease of a structured programme of follow-up care provided by practice nurses (PNs) in general practice in England. It is based on in-depth interviews with 22 patients receiving an integrated primary and secondary care intervention being developed and piloted for patients following heart attack or diagnosis of angina. Patients identified the important features of follow-up care to be easy access to a health professional who possessed knowledge and social and emotional skills. A range of views about the ability of PNs to provide such care emerged from patients' accounts. patients' perceptions about the seriousness of their condition and the way PN follow-up care was provided in practices emerged as important issues affecting patients' views. In addition, perceptions about the practice nurse's role, status and knowledge, existing relationships with general practitioners, and issues of communication were also important factors. It is concluded that in order to develop high-quality PN-led services for patients with established heart disease, four issues need to be taken into account: practice nurse training; continuity of follow-up care; the integration of the primary and secondary care interface; and development of the practice nurse's status within the primary health care team.     

Immunology

A selection of interesting papers that were published in the two months before our press date in major journals most likely to report significant results in immunology.     

Hypercoagulability in a patient with Marfan syndrome.

A 39 year old man with Marfan syndrome presented with multiple pulmonary emboli and renal, hepatic, and splenic infarcts of unknown aetiology. The combination of thromboemboli and physical features initially suggested homocystinuria; however, laboratory examination showed no evidence for this disorder. Laboratory evaluation identified no coagulation abnormalities. This patient represents the unusual occurrence of hypercoagulability in a patient with Marfan syndrome.     

Metabolic myocardial viability assessment with iodine 123-16-iodo-3-methylhexadecanoic acid in recent myocardial infarction: Comparison with thallium-201 and fluorine-18 fluorodeoxyglucose

The best test presently available to ascertain residual viability within an infarct-related area involves the use of fluorine-18 fluorodeoxyglucose (FDG) to detect the persistence of some cellular metabolism. Rest reinjection of thallium-201 is a less accurate alternative but is easy to perform. Iodinated fatty acids, which are used with standard gamma cameras, are proposed as markers of cellular metabolism. This study was performed to assess the value of 16-iodo-3-methyl-hexadecanoic acid (MIHA) as a marker of the residual cellular metabolism by comparison with FDG in patients with a recent myocardial infarction, and to evaluate its contribution compared with the²⁰¹Tl stress-redistribution-reinjection technique. Stress-redistribution-reinjection²⁰¹T1 imaging, rest MIHA imaging and glucoseloaded FDG imaging were performed in 22 patients with recent myocardial infarction. Out of the 628 myocardial segments obtained from the left ventricular analysis, 400 were hypoperfused (relative uptake <0.75 of maximum uptake on stress²⁰¹T1 imaging), 177 of which were severely hypoperfused (relative uptake <0.50). Receiver operating characteristic (ROC) curves for predicting metabolic myocardial viability with FDG were derived from the results in respect of (a)²⁰¹T1 activity during exercise, redistribution and reinjection and (b) MIHA up-take, using the two FDG thresholds most commonly considered to define metabolic viability (0.50 and 0.60). Analysis of the 400 hypoperfused segments demonstrated that²⁰¹T1 reinjection was the most accurate test in predicting the presence of myocardial viability (area under the ROI curves=0.85 and 0.86 at the 0.50 and 0.60 FDG thresholds, respectively;P<0.05 vs other tests). The global predictive values of MIHA and²⁰¹T1 reinjection were, respectively, 0.87 and 0.89 at the 0.50 FDG threshold (NS), and 0.82 and 0.87 at the 0.60 FDG threshold (NS). When only the 177 severely hypoperfused segments were considered,²⁰¹T1 reinjection remained the most accurate test (accuracy 0.84 at the 0.50 FDG threshold and 0.82 at the 0.60 FDG threshold), while the accuracy of MIHA decreased significantly (0.78 at the 0.50 FDG threshold and 0.73 at the 0.60 FDG threshold,P<0.05 vs²⁰¹T1 reinjection). In all circumstances, MIHA was less specific than²⁰¹T1 reinjection for the detection of metabolic viability. In conclusion, in patients with recent myocardial infarction, MIHA accurately detects the persistence of metabolic viability, but is not superior to²⁰¹T1.