Prospective study of heart rate variability and mortality in chronic heart failure: results of the United Kingdom heart failure evaluation and assessment of risk trial (UK-heart)

BACKGROUND

Patients with chronic heart failure (CHF) have a continuing high mortality. Autonomic dysfunction may play an important role in the pathophysiology of cardiac death in CHF. UK-HEART examined the value of heart rate variability (HRV) measures as independent predictors of death in CHF.

METHODS AND RESULTS

In a prospective study powered for mortality, we recruited 433 outpatients 62+/-9.6 years old with CHF (NYHA functional class I to III; mean ejection fraction, 0.41+/-0.17). Time-domain HRV indices and conventional prognostic indicators were related to death by multivariate analysis. During 482+/-161 days of follow-up, cardiothoracic ratio, SDNN, left ventricular end-systolic diameter, and serum sodium were significant predictors of all-cause mortality. The risk ratio for a 41.2-ms decrease in SDNN was 1.62 (95% CI, 1.16 to 2.44). The annual mortality rate for the study population in SDNN subgroups was 5.5% for >100 ms, 12.7% for 50 to 100 ms, and 51.4% for <50 ms. SDNN, creatinine, and serum sodium were related to progressive heart failure death. Cardiothoracic ratio, left ventricular end-diastolic diameter, the presence of nonsustained ventricular tachycardia, and serum potassium were related to sudden cardiac death. A reduction in SDNN was the most powerful predictor of the risk of death due to progressive heart failure.

CONCLUSIONS

CHF is associated with autonomic dysfunction, which can be quantified by measuring HRV. A reduction in SDNN identifies patients at high risk of death and is a better predictor of death due to progressive heart failure than other conventional clinical measurements. High-risk subgroups identified by this measurement are candidates for additional therapy after prescription of an ACE inhibitor.

"Value" of improved treadmill exercise capacity: lessons from a study of rate responsive pacing

OBJECTIVES

To compare the value of a series of cardiovascular measurements in patients with symptomatic disease receiving an effective treatment (rate responsive pacing).

PATIENTS

12 pacemaker dependent patients with VVIR units.

INTERVENTIONS

Single blind crossover between VVI and VVIR.

OUTCOME MEASURES

Exercise capacity was assessed by treadmill tests (modified Bruce protocol and a fixed workload protocol) with respiratory gas analysis. Self paced corridor walk tests were also undertaken. Quality of life (QOL) was assessed by questionnaire. Daily activity was measured in the patients' homes using shoe and belt pedometers.

RESULTS

Treadmill tests and QOL questionnaires correctly identified the clinical benefit associated with VVIR. The modified Bruce protocol was superior to the fixed workload protocol as it was better tailored to the fairly well preserved exercise capacity of the patients. Symptom scores, but not walking times, were improved with VVIR during corridor walk tests. VVIR did not improve daily activity measured using either the belt or shoe pedometers.

CONCLUSIONS

VVIR pacing improved some but not all measures of exercise capacity. This finding illustrates the difficulty of selecting an instrument to measure symptomatic improvement in clinical research; and raises the question, what is the best way of measuring exercise capacity?

Isolation of dominant seizure foci by multiple subpial transections

Dominant seizure foci (DSF) are seizure foci that do not respond to multiple subpial transections (MST). DSF were isolated in 15/31 patients who underwent MST in the past 6 years. These patients had MST over both hemispheres (6 patients) or over multiple lobes of one hemisphere (9 patients). DSF measured 0.5-1 cm in diameter and numbered 1-4 (in each patient). Their excision resulted in dramatic improvement in EEG over wide areas of the cortex. The longest postoperative follow-up is 67 months, with a median of 21 months. Nine of 15 patients are free of seizures, 3/15 have rare seizures, 2/15 have > 90% reduction in seizure frequency, and 1/15 has > 70% reduction in seizure frequency with improvement in motor and speech functions. In summary, DSF are resistant to MST and influence the electrical activity of the surrounding cortex. MST combined with excision of DSF resulted in good seizure control in this series, which included patients with multilobar and bihemispheric seizure foci.

Robotic multimodality stereotactic brain tissue identification: work in progress

Real-time identification of tissue would improve procedures such as stereotactic brain biopsy (SBX), functional and implantation neurosurgery, and brain tumor excision. To standard SBX equipment has been added: (1) computer-controlled stepper motors to drive the biopsy needle/probe precisely; (2) multiple microprobes to track tissue density, detect blood vessels and changes in blood flow, and distinguish the various tissues being penetrated; (3) neural net learning programs to allow real-time comparisons of current data with a normative data bank; (4) three-dimensional graphic displays to follow the probe as it traverses brain tissue. The probe can differentiate substances such as pig brain, differing consistencies of the 'brain-like' foodstuff tofu, and gels made to simulate brain, as well as detect blood vessels imbedded in these substances. Multimodality probes should improve the safety, efficacy, and diagnostic accuracy of SBX and other neurosurgical procedures.

Spontaneous cervical hemorrhage with near-complete airway obstruction

BACKGROUND

Retropharyngeal hematoma is a rare entity which may progress rapidly to airway obstruction. Previously documented causes have included coagulopathic states, trauma, infection, parathyroid adenoma rupture, and foreign-object ingestion. Four cases of spontaneous retropharyngeal hematomas without any known predisposing risk factors have been previously reported. Two of these cases had fatal outcomes.

METHODS

A case report is presented and the literature reviewed.

RESULTS

Spontaneous cervical hematoma with parapharyngeal and retropharyngeal involvement which caused near-complete respiratory obstruction occurred in an otherwise healthy young man following straining. Initial management involved fiberoptic nasotracheal intubation. Subsequent right neck exploration revealed hemorrhage from a branch of the external carotid artery, which was ligated. An arteriogram revealed minimal flow through the right external carotid artery and its branches. The patient was extubated and discharged uneventfully on the fourth postoperative day.

CONCLUSION

The possible etiology for this case is discussed, and a review of the literature and the role of surgery in the management of this entity is outlined.

Objective measures of laryngeal function after reinnervation of the anterior and posterior recurrent laryngeal nerve branches

Previous research indicates that separate reinnervation of the anterior and posterior branches of the recurrent laryngeal nerve (RLN) can provide purposeful motion of the larynx, even after transplantation. This canine study was undertaken to better determine the results of RLN reinnervation after nerve transection distal to its bifurcation. This approximates ideal conditions for transplantation, because potential rejection and nerve branch mismatch are eliminated. Eight months after nerve repair, video, electromyographic, mechanical, and histologic data were collected on four canines. Results show return of appropriate motion without synkinesis, including purposeful abduction on endotracheal tube occlusion. Abductory function was weaker on the reinnervated side, but adduction was equal or stronger on the reinnervated vocal cord. These results indicate that this method of RLN reinnervation produces consistent, strong physiologic motion in the denervated larynx.

The effect of dietary creatine supplementation on skeletal muscle metabolism in congestive heart failure

AIMS

To assess the effects of dietary creatine supplementation on skeletal muscle metabolism and endurance in patients with chronic heart failure.

METHODS

A forearm model of muscle metabolism was used, with a cannula inserted retrogradely into an antecubital vein of the dominant forearm. Maximum voluntary contraction was measured using handgrip dynanometry. Subjects performed handgrip exercise, 5 s contraction followed by 5 s rest for 5 min at 25%, 50%, and 75% of maximum voluntary contraction or until exhaustion. Blood was taken at rest and 0 and 2 min after exercise for measurement of lactate and ammonia. After 30 min the procedure was repeated with fixed workloads of 7 kg, 14 kg and 21 kg. Patients were assigned to creatine 20 g daily or matching placebo for 5 days and returned after 6 days for repeat study.

RESULTS

Contractions (median (25th, 75th interquartiles)) until exhaustion at 75% of maximum voluntary contraction increased after creatine treatment (8 (6, 14) vs 14 (8, 17), P = 0.025) with no significant placebo effect. Ammonia per contraction at 75% maximum voluntary contraction (11.6 mumol/l/contraction (8.3, 15.7) vs 8.9 mumol/l/contraction (5.9, 10.8), P = 0.037) and lactate per contraction at 75% maximum voluntary contraction (0.32 mmol/l/contraction (0.28, 0.61) vs 0.27 mmol/l/contraction (0.19, 0.49), P = 0.07) fell after creatine but not after placebo.

CONCLUSIONS

Creatine supplementation in chronic heart failure augments skeletal muscle endurance and attenuates the abnormal skeletal muscle metabolic response to exercise.

Cytotoxicity of xenobiotics and expression of glutathione-S-transferases in immortalised rat hepatocyte cell lines

1. Immortalised rat hepatocyte cell lines are more sensitive to the cytotoxicity of 1-chloro-2,4-dinitrobenzene and ethacrynic acid than primary cultures of hepatocytes. 2. Class alpha glutathione S-transferases are not expressed in immortalised hepatocyte cell lines. Class pi glutathione S-transferase expression is elevated in the immortalised cell lines compared with freshly isolated hepatocytes, but it is not as high as in the HTC rat hepatoma cell line. 3. Immortalised hepatocyte cell lines may provide a sensitive model system for detecting cytotoxicity associated with xenobiotics which are detoxified by glutathione S-transferases.

Racial and gender differences in use of procedures for black and white hospitalized adults

A number of studies have found that blacks and females with coronary heart disease are less likely to undergo major diagnostic and therapeutic procedures than whites and males, even after controlling for severity of illness and other indicators of physical condition. This investigation examined 78 conditions treated in acute care hospitals to identify possible variations in medical treatment by race and gender among blacks and whites. The study is unique in examining such a wide range of conditions and in using an all-payer national sample. The study examines over 1.7 million inpatient discharge abstracts from the Hospital Cost and Utilization Project, a national sample of about 500 hospitals in the United States. Logistic regression modeling was used to describe the influence of race and gender among blacks and whites on the likelihood of having a major therapeutic or major diagnostic procedure, controlling for patient age, disease severity, health insurance and hospital-level characteristics. The study found that blacks were less likely than whites to receive major therapeutic procedures in 37 of 77 (48%) conditions, and females were less likely than males to receive major therapeutic procedures for 32 of 62 (52%) conditions. The proportion of conditions in which blacks and females were less likely to receive a major diagnostic procedure (without a major therapeutic procedure) was 21% and 26%, respectively. This study identified a number of conditions with apparent variations in medical treatment by race or gender among blacks and whites that should be targeted for more detailed investigations.

Effects of amlodipine in patients with chronic heart failure

The role of calcium antagonists in patients with ischemic heart failure is currently unclear. We examined the effects of amlodipine on exercise capacity and central and regional hemodynamics in 32 patients with mild to moderate chronic heart failure in a single-center, double-blind, randomized placebo-controlled trial. All were taking at least 40 mg of furosemide daily with an angiotensin-converting enzyme inhibitor. Ischemic heart disease was the most common cause of heart failure, but no patient had symptom-limiting angina. Mean treadmill exercise capacity in patients taking amlodipine increased by 96 seconds (95% confidence interval -23 to 215) and 50 seconds (-34 to 135) in the placebo group; mean difference in change between treatments was 70 seconds (-90 to 233), p = 0.38. Active treatment with amlodipine did not affect self-paced corridor walking times. Similarly, there were no significant effects on cardiac output, oxygen uptake, heart rate, and mean arterial pressure at rest or during exercise. Calf and renal blood flow were also unchanged by treatment. The lack of significant effect demonstrated by these data suggests a limited role for amlodipine in patients with ischemic cardiomyopathy, although it may prove beneficial in those with nonischemic disease. More data are required before amlodipine can be recommended for all patients with chronic heart failure.

Australia's notifiable diseases status, 1996. Annual report of the National Notifiable Diseases Surveillance System

In 1996 there were 65,024 notifications to the National Notifiable Diseases Surveillance System. The record high number of Ross River virus infection notifications was of particular note. The highest rates were recorded in Western Australia, where an outbreak was documented in the South West, and in Queensland. Most cases occurred in the late summer and early autumn months. The number of measles cases has continued to fall markedly following the outbreak in 1993 and 1994. Rubella notifications also fell in 1996. The number of cases of pertussis remained at a similar level to that recorded in recent years, the highest notification rate being recorded for children under the age of one year. A peak in late 1996 marked a resurgence in the pertussis epidemic which has continued into 1997. Notifications of Haemophilus influenzae type b continued to decline reaching a record low rate of 0.3 notifications per 100,000 population. For the enteric diseases, the number of cases of campylobacteriosis rose, with an annual adjusted notification rate of 100.4 per 100,000 population; more notifications were received for this disease than for any other in 1996. The number of hepatitis A cases also rose relative to 1995. This is a reversal of the trend observed in recent years when the notification rate fell. The number of cases of salmonellosis and shigellosis remained stable. Notifications for chlamydial infection and gonococcal infection rose relative to 1995, whilst those for syphilis fell.

The case for national health data standards

The Health Insurance Portability and Accountability Act of 1996 (HIPAA) contains groundbreaking provisions to encourage the development of a national health information system through the establishment of standards. This paper compares statewide inpatient data systems to one standard--the Uniform Bill (UB)--to understand how standards have been used and how they can be improved. We recommend changes to the UB, note the need for better compliance, and suggest new standards for common, derived elements.

Pertussis notifications in Australia, 1991 to 1997

Although pertussis is a vaccine-preventable disease, it has been epidemic in Australia since 1993 and recently claimed the lives of four children under three months of age. We reviewed national notifications of pertussis from 1991 to 1997 and found notification rates ranged from 2.0 per 100,000 population in 1991 to a peak of 30.5 per 100,000 population in 1994 despite pertussis vaccination coverage approaching 90% for the three-dose primary course. We found that notification rates were highest in infants (< 1 year of age) and school aged children (5-14 years of age). Although there was a resurgence of pertussis in 1996, age-specific notification rates decreased for children aged 1-7 years and it appears that the diphtheria-tetanus-pertussis (DTP) booster introduced as a fifth dose at 4-5 years may be having an effect. We raise the possibility that the current whole cell pertussis vaccine may be providing only short-term immunity and that our results may reflect low or inadequate vaccine coverage among both the population at large and the individual cases. We identify gaps in the national surveillance system which require attention including under-reporting and the need for information on vaccination status of notified cases; method of diagnosis; and date of birth or age in months to identify the proportion of infants in the highest risk group, that is under six months of age.

Relation of daily activity levels in patients with chronic heart failure to long-term prognosis

Symptom-limited, laboratory-based exercise tests are often used to define prognosis in patients with chronic heart failure, but they do not relate to measures of normal daily activity. Invasive measures of central hemodynamics similarly relate poorly to outcome. Pedometer scores of weekly walking are markedly reduced in patients with heart failure, but whether this less artificial measure of exercise capacity is important in predicting prognosis is not known. Eighty-four patients with chronic heart failure were followed for a mean of 710 days during which 44 died and 3 underwent cardiac transplantation. Symptom-limited treadmill exercise capacity using 2 different protocols did not predict survival, whereas reduced weekly pedometer scores were strong predictors of death (p < 0.001). Other variables that predicted death included resting cardiac output, arterial blood pressure, diuretic requirements, New York Heart Association class, increased bilirubin, and hyponatremia (all p < 0.01). Reduced levels of daily activity are strong predictors of death in chronic heart failure and appear more powerful than laboratory-based exercise tests. This type of assessment is valuable in identifying patients at high risk and provides an objective measure of incapacity during normal daily life. The exercise capacity of patients unable to exercise in the laboratory could also be assessed using this technique. This may prove invaluable in clinical and mortality trials.

A double-blind, cross-over comparison of the effects of a loop diuretic and a dopamine receptor agonist as first line therapy in patients with mild congestive heart failure

We compared the effects of the orally active dopamine agonist ibopamine with the loop diuretic frusemide as first-line therapy in patients with mild congestive heart failure. Fourteen patients with New York Heart Association class II congestive heart failure were enrolled in a double-blind, cross-over study. After baseline measurements of clinical and symptomatic status, modified Bruce exercise time, high-level exercise time, corridor walk time, regional blood flow, pedometer scores, 24 h urine volume and sodium excretion and neurohumoural factors, patients were randomly allocated to receive either frusemide 40 mg o.d. or ibopamine 100 mg t.d.s. for 8 weeks. Assessments were performed at 2 weekly intervals. After 8 weeks, patients crossed over into the alternate treatment arm for a further 8 weeks, with further assessments performed every 2 weeks. There were four exacerbations of heart failure during ibopamine treatment and none during frusemide treatment. After 8 weeks of treatment, modified Bruce exercise time was 901 +/- 73 s with frusemide and 646 +/- 134 s with ibopamine (P < 0.05). Twenty-four hour urinary sodium excretion at weeks 2 and 4 (P < 0.05), and 24 h urinary volume at week 2 (P = 0.0001) were lower during ibopamine treatment. At week 8, supine (P = 0.076) and erect renin (P = 0.05) were lower with ibopamine treatment. In conclusion, ibopamine is ineffective as first line therapy for congestive heart failure, probably because of a lesser diuretic potency than frusemide.

Concurrent outbreaks of Salmonella Typhimurium in South Australia

The Communicable Disease Control Branch of the South Australian Health Commission received 45 laboratory notifications of Salmonella between 23 December 1996 and 17 January 1997. A rapid screening test, undertaken by the Institute of Medical and Veterinary Sciences, Adelaide, was the first indication that this was more than one outbreak, prompting the establishment of separate investigations. Three Salmonella Typhimurium (S. Typhimurium) phage types were subsequently identified. Investigations are continuing into an outbreak of S. Typhimurium phage type (PT) 64, while investigations failed to identify any association between four cases of PT 44. As of 12 February 1997, 71 notifications had been confirmed as S. Typhimurium PT 135. Epidemiological investigations found this outbreak was associated with consumption of bread rolls with a meat filling distributed through local Asian grocery stores from a home-based manufacturer. The product was voluntarily withdrawn and there have been no new cases of PT 135.

Abnormalities of skeletal muscle metabolism in patients with chronic heart failure: evidence that they are present at rest

OBJECTIVE

To investigate abnormalities of skeletal muscle metabolism in patients with congestive heart failure.

SETTING

A university teaching hospital.

METHODS

43 patients (22 New York Heart Association (NYHA) grade II, 21 grade III) and 10 controls were studied. A forearm model of muscle metabolism was used, with a cannula inserted retrogradely into an antecubital vein of the dominant forearm. Maximum voluntary contraction (MVC) was measured using handgrip dynamometry. Subjects performed handgrip exercise, 5 s contraction followed by 5 s rest for 5 min at 25%, 50%, and 75% of MVC or until exhaustion. Blood was taken at rest and 0 and 2 min after exercise for measurement of lactate and ammonia. After 30 min the procedure was repeated with fixed workloads of 7 kg, 14 kg, and 21 kg.

RESULTS

MVC (kg, mean (SEM)) was lower in patients than in controls (control 42.45 (2.3); NYHA II 34.13 (1.3), P = 0.003; NYHA III 33.13 (1.94), P = 0.008). Resting lactate (mmol/l) was higher in patients than controls (control 0.65 (0.06); NYHA II 0.84 (0.08), P = 0.13; NYHA III 1.18 (0.1), P = 0.002). Resting ammonia (mumol/l) was higher in NYHA III (65.7 (6.0)) than in NYHA II (48.0 (3.7), P = 0.016); no difference was found between controls (48.0 (7.1)) and patients. The overall lactate and ammonia response to exercise was greater in NYHA III than in NYHA II and controls (P < 0.05). At volitional exhaustion, peak lactate (mmol/l: NYHA III 3.31 (0.26); NYHA II 2.56 (0.16); controls 2.71 (0.22); P = 0.022 NYHA III v NYHA II) and ammonia (mumol/l: NYHA III) 126.4 (8.97); NYHA II 92.9 (7.23); controls 109 (16.3); P = 0.006 NYHA III v NYHA II) were higher in severe congestive heart failure.

CONCLUSIONS

Skeletal muscle metabolism is abnormal at rest in congestive heart failure. During exercise, the degree of metabolic abnormality is related to the symptomatic status of the patient.

Evaluation of health promotion activities in community nursing practice

The purpose of this research was to study the extent to which community nurses (CNs) were involved in health promotion activities and to investigate whether these activities were meeting the needs of their clients. A cross-sectional survey by multiple methods was designed and carried out in four district health authorities (DHAs) in one regional health authority in England. Two hundred and fifty-one (83.67%) completed questionnaires were returned by CNs working in primary health care (PHC). Sixty sessions with CNs were observed and 249 interviews were conducted with clients. Additionally, as part of the observation 155 clinical records were examined. CNs reported involvement in a wide range of opportunistic and organized health promotion activities. Lifestyle advice and ill-health prevention were most frequently used by all groups. Health visitors (HVs) were involved significantly more in group and community wide activities. District nurses (DNs) were mainly involved in opportunistic health promotion. Practice nurses (PNs) were found to be involved significantly more in health promotion activities organized on an individual basis. Observation revealed that opportunistic health promotion was carried out in almost half of the consultations observed, of which lifestyle advice was the most frequent. Records however showed that this information was rarely recorded. The clients of PNs were mostly aware of other health promotion activities available within the general practice, while almost half of the HVs' clients knew what other health promotion activities were available to them and few DNs' clients were aware of any.

Inspiratory muscle endurance in patients with chronic heart failure

OBJECTIVE

To assess the significance of changes in respiratory muscle endurance in relation to respiratory and limb muscle strength in patients with mild to moderate chronic heart failure using a threshold loading technique.

SUBJECTS

20 patients with chronic heart failure (17 male) aged 63.8 (SD 7.4) years and 10 healthy men aged 63.1 (5.6) years. Heart failure severity was New York Heart Association (NYHA) grade II (n = 11) and NYHA grade III/IV (n = 9).

METHODS

Respiratory muscle strength was measured from mouth pressures during maximum inspiratory effort (MIP) at functional residual capacity (FRC) and limb muscle strength was measured using a hand grip dynamometer. Inspiratory muscle endurance was measured using a threshold loading technique. The total endurance duration, the maximum threshold pressure achieved (P-Max), and the inspiratory load (% ratio of P-Max/MIP) were recorded in all subjects.

RESULTS

Inspiratory muscles were weaker in patients with heart failure than in the controls [MIP 53.6 (16.5) v 70.9 (20.2) cm H2O, P < 0.05]. Hand grip strength was similar in both subject groups [31.6 (SD) v 36.1 (15.9) dynes]. Total endurance duration was significantly reduced in the patient group [494 (223) v 996 (267) s, P < 0.01], as was the maximal threshold pressure achieved [P-Max 18.5 (6.4) v 30.7 (6.6) cm H2O, P < 0.01]. When expressed as a percentage of MIP, P-Max was also lower in the patients [35.2 (11.8) v 44.8 (11.4)%, P < 0.05]. There was no significant correlation between any measure of endurance and limb muscle strength.

CONCLUSIONS

Respiratory muscle endurance is reduced in patients with chronic heart failure. These changes probably reflect a generalised skeletal myopathy and provide further evidence of respiratory muscle dysfunction in patients with this disease. Respiratory muscle endurance needs now to be related to symptoms and the effects of treatment and respiratory muscle training should also be explored.

Malignant Post-Vietnam Stress Syndrome revisited

Malignant Post-Vietnam Stress Syndrome describes a severe form of combat-related posttraumatic stress disorder. We update the concept of Malignant Post-Vietnam Stress Syndrome, considering the effects of repeated severe traumatization, exposure to atrocities, and a variety of comorbid conditions. An illustrative case report demonstrates an interdisciplinary treatment approach, combining case management, brief hospitalizations, symptom-directed use of medications, and supportive psychotherapy.