Cheyne-Stokes respiration in congestive heart failure.

Cheyne-Stokes respiration is an abnormal breathing pattern which commonly occurs in patients with decompensated congestive heart failure and neurologic diseases, in whom periods of tachypnea and hyperpnea alternate with periods of apnea. In the majority of these patients, the ventilatory patterns may not be recognized, and the clinical features are generally dominated by the underlying disease process. Cheyne-Stokes respiration may, however, have profound effects on the cardiopulmonary system, causing oxygen desaturation, cardiac arrhythmias, and changes in mental status. Treatment of Cheyne-Stokes respiration in congestive heart failure with supplemental oxygen or nasal continuous positive airway pressure, in addition to conventional therapy, may improve the overall cardiac function and perhaps the patient's prognosis.     

Temperature-dependent skeletal muscle dysfunction in rats with congestive heart failure.

Abnormalities in the excitation-contraction coupling of slow-twitch muscle seem to explain the slowing and increased fatigue observed in congestive heart failure (CHF). However, it is not known which elements of the excitation-contraction coupling might be affected. We hypothesize that the temperature sensitivity of contractile properties of the soleus muscle might be altered in CHF possibly because of alterations of the temperature sensitivity of intracellular Ca(2+) handling. We electrically stimulated the in situ soleus muscle of anesthetised rats that had 6-wk postinfarction CHF using 1 and 50 Hz and using a fatigue protocol (5-Hz stimulation for 30 min) at 35, 37, and 40 degrees C. Ca(2+) uptake and release were measured in sarcoplasmic reticulum vesicles at various temperatures. Contraction and relaxation rates of the soleus muscle were slower in CHF than in sham at 35 degrees C, but the difference was almost absent at 40 degrees C. The fatigue protocol revealed that force development was more temperature sensitive in CHF, whereas contraction and relaxation rates were less temperature sensitive in CHF than in sham. The Ca(2+) uptake and release rates did not correlate to the difference between CHF and sham regarding contractile properties or temperature sensitivity. In conclusion, the discrepant results regarding altered temperature sensitivity of contraction and relaxation rates in the soleus muscle of CHF rats compared with Ca(2+) release and uptake rates in vesicles indicate that the molecular cause of slow-twitch muscle dysfunction in CHF is not linked to the intracellular Ca(2+) cycling.     

Nocturnal oxygen desaturation in patients with congestive heart failure

The aim of our study was to evaluate the modifications of the respiratory pattern during sleeping in patients with congestive heart failure (CHF) by a simple pulse-oxymetry. We studied 10 subjects (8M/2F), mean age 71.4 +/- 12.4 yrs, admitted to sub-intensive cardiological therapy unit, with diagnosis of CHF due to left ventricular insufficiency by ischemic, hypertensive or idiopathic cardiopathy, when in a stable clinical condition. All patients presented arterial blood gas values within normal limits. The ejection fraction of left ventricle showed a mean value of 30.4 +/- 8.2% (range 20%-45%). Nocturnal pulse-oxymetry was performed by pulse-oxymeter (PULSOX 7 Minolta) provided with a digital probe at a sliding speed 24 cm/h. Our data showed that all patients presented nocturnal desaturation episodes (mean oxygen desaturation index 15.7 +/- 18.4). In two patients, we found an "Overlap Syndrome" (obstructive sleep apnoea in presence of cardiopathy). In other patients pulse-oxymetry showed a typical sequence of "fall-rise" basal O2 saturation lasting from 36 to 72 seconds, collected in "wave trains" which were present from 14% to 70% of total sleep time compatible with periodic breathing. In conclusion, our study shows that patients affected by CHF, even if in stable condition and with a PaO2, within normal values, present more or less severe disturbances of nocturnal SaO2, with periodic and regular sequences of SaO2 fall-rise that may be referred to ventilatory troubles such as periodic breathing or Cheyne-Stokes breathing. In these patients the pulse-oxymetry may be considered an efficacious, simple, cheap and well tolerated method.     

Left ventricular pacing in patients with congestive heart failure

Cardiac resynchronisation therapy (CRT) using biventricular (BIV) pacing has proved its effectiveness to correct myocardial asynchrony and improve clinical status of patients with severe congestive heart failure (CHF) and widened QRS. Despite a different effect on left ventricular electrical dispersion, left univentricular (LV) pacing is able to achieve the same mechanical synchronisation as BIV pacing in experimental studies and in humans. This results in clinical benefits of LV pacing at mid-term follow-up, with significant improvement in functional class, quality of life and exercise tolerance at the same extent as those observed with BIV stimulation in non randomised studies. Furthermore these benefits are obtained at lesser costs and with conventional dual-chamber devices. However, LV pacing has to be compared to BIV pacing in randomised trials before being definitely considered as a cost-effective alternative to BIV pacing.     

Role of endothelins in congestive heart failure

Despite major advances in conventional medical therapy, patients with heart failure continue to experience significant morbidity and mortality. Endothelin-1 (ET-1) is a potent vasocontrictor and mitogenic peptide that is activated in heart failure. There is increasing experimental and clinical evidence in support of an important role of ET-1 in the pathophysiology of heart failure. Manipulation of the activity of ET-1, especially using endothelin receptor blockers, has allowed for the further elucidation of the role of this neurohormonal system and development of novel therapeutic strategies in heart failure. Published clinical studies of these agents to date have involved relatively small numbers of patients with severe heart failure, followed for a relatively short period of time, and have mainly examined surrogate endpoints. Large-scale trials that address to hard clinical outcomes are ongoing and their results forthcoming. A key question that remains concerns whether selective ETA or dual ETA-ETB receptor blockade will be more effective.     

Impact of specialist follow-up in outpatients with congestive heart failure

Background

There is uncertainty about whether physician specialty influences the outcomes of outpatients with congestive heart failure after adjustment for differences in case mix. Our objective was to determine the impact of physician specialty on outcomes in outpatients with new-onset congestive heart failure.

Methods

The study was a population-based retrospective cohort study involving patients with new-onset congestive heart failure discharged from 128 acute care hospitals in Alberta between Apr. 1, 1998, and July 1, 2000. Outcomes were resource utilization (clinic visits, emergency department visits and hospital admissions) and survival at 30 days and 1 year.

Results

A total of 3136 patients were discharged from hospital with a new diagnosis of congestive heart failure (median age 76 years, 50% men). Of these, 1062 (34%) received no follow-up visits for cardiovascular care, 738 (24%) were seen by a family physician (FP) alone, 29 (1%) by a specialist (cardiologist or general internist) alone and 1307 (42%) by both a specialist and an FP. Compared with patients who received no follow-up cardiovascular care, patients who received regular cardiovascular follow-up visits with a physician had fewer visits to the emergency department (38% v. 80%), fewer were admitted to hospital (13% v. 94%), and the adjusted 1-year mortality was lower (22% v. 37%) (all p < 0.001). Compared with patients who received combined specialist and FP care, patients cared for exclusively by FPs had fewer outpatient visits (median 9 v. 17 in the first year), fewer of these patients presented to the emergency department (24% v. 45% in the first year), and fewer were readmitted for cardiovascular care (7% v. 16%) (all p < 0.001). However, the adjusted mortality at 1 year was lower among patients treated with combined care (17% v. 28%, p < 0.001) despite a higher burden of comorbidities. In a multivariate model adjusting for comorbidities (with no cardiovascular follow-up visits as the reference category), the mortality was lower among patients followed on an outpatient basis by an FP alone (odds ratio [OR] 0.66, 95% confidence interval [CI] 0.53–0.82) or by an FP and a specialist (OR 0.34, 95% CI 0.28–0.42). In a proportional hazards model with time-dependent covariates (with adjustment for frequency of follow-up visits), the risk of all-cause mortality was reduced significantly (hazard ratio 0.98, 95% CI 0.97– 0.99) with each specialist visit compared with FP care alone.

Interpretation

Patients with congestive heart failure followed by both specialists and FPs had significantly better survival than those followed by FPs alone (or those who received no specific cardiovascular follow-up care). Methods to improve timely and appropriate access to specialists and to improve collaborative care structures are needed.Congestive heart failure (CHF) afflicts up to 2% of North American adults and, despite many advances in diagnosis and therapy, still portends a poor prognosis, with 1-year mortality of 30%–50%.^1,2,3,4,5 Although the prognosis of patients with CHF is poor even with optimal management, suboptimal diagnosis, investigation and treatment of heart failure and comorbidities (e.g., coronary artery disease) in community-dwelling patients contributes to poor survival.^6,7,8,9In previous studies hospital inpatients with CHF who were cared for by specialists received more evidence-based therapies and had better outcomes than those cared for by nonspecialists.^{8,10,11,12,13} However, none of these studies examined the care delivered after discharge from hospital. Although management in specialized multidisciplinary clinics is associated with better outcomes,¹⁴ it is unclear whether similar benefits can be expected when patients are cared for by specialist physicians operating outside the setting of a multidisciplinary clinic. Two recent studies from the United States that reported better outcomes with specialist care^7,15 were flawed, in that neither study adjusted for frequency of outpatient visits or the possibility of time-dependent bias¹⁶ (whereby some variables, including the number of visits, will change over time).To address this important public health issue, we sought to determine whether there is a relation between ambulatory care follow-up and outcomes in patients with new-onset CHF.