Excessive breathlessness in patients with diastolic heart failure.

OBJECTIVES: To establish the prevalence of preserved left ventricular (LV) systolic function (PSF) in 435 consecutive symptomatic patients referred to a heart failure clinic and to examine their ventilatory response to exercise when compared with 134 control volunteers. METHODS: 216 (50%) patients had systolic heart failure (SHF) (ejection fraction < 45%). 51 (11%) had an immediately apparent alternative causes of breathlessness and 168 (39%), with no obvious other cause of breathlessness, were divided into those with PSF and diastolic dysfunction (DD) (PSF(DD); n = 113 or 26% of referrals) and those without DD (PSF(N); n = 55 or 13% of referrals). The controls were divided into those with (C(DD); n = 32) and those without (C(N); n = 102) echocardiographic evidence of DD. RESULTS: Patients with SHF had lower peak oxygen consumption (pVo(2)), steeper slope of minute ventilation (Ve) to carbon dioxide production, lower exercise time and shorter 6 min walk test than PSF patients and controls. PSF(DD) patients had lower pVo(2), exercise time and 6 min walk test than C(DD), although their echocardiograms were not different. Exercise capacity did not differ between PSF(DD) and PSF(N) patients. The slope relating Ve to symptoms (Borg/Ve slope) was less steep in those with SHF than in PSF(DD) (0.17 (0.04) v 0.20 (0.08), p < 0.05) and in PSF(N) (0.19 (0.10), p < 0.05), implying greater symptoms of breathlessness for a given level of Ve. Both PSF groups had a steeper slope than C(DD) (0.14 (0.09), p < 0.05 for both comparisons). CONCLUSIONS: Patients with PSF have exercise tolerance intermediate between that of patients with SHF and controls. Exercise tolerance is similar in PSF(DD) and PSF(N). Both groups have worse exercise tolerance than C(DD). PSF(DD) and PSF(N) patients seem to experience a greater awareness of Ve than C(DD) and patients with SHF.

Chronic heart failure, chronotropic incompetence, and the effects of beta blockade.

OBJECTIVE: To establish the prevalence of chronotropic incompetence in a cohort of patients with chronic heart failure (CHF) taking modern medications for heart failure, and whether this affected exercise capacity and predicted prognosis. METHODS: Heart rate response to exercise was examined in 237 patients with CHF in sinus rhythm, who were compared with 118 control volunteers. The percentage of maximum age predicted peak heart rate (%Max-PPHR) and percentage heart rate reserve (%HRR) were calculated, with a cut off of < 80% as the definition of chronotropic incompetence for both. Patients were followed up for an average (SD) of 2.8 (9) years. Mortality was related to peak oxygen consumption (pVo2), and the presence or absence of chronotropic incompetence. RESULTS: %Max-PPHR < 80% identified 103 (43%) and %HRR < 80% identified 170 patients (72%) as having chronotropic incompetence. Chronotropic incompetence was more common in patients taking beta blockers than in those not taking beta blockers as assessed by both methods (80 (49%) v 23 (32%) by %Max-PPHR and 123 (75%) v 47 (64%) by %HRR, respectively). Patients with chronotropic incompetence by either method had a lower pVo2 than those without. These differences remained significant for both patients taking and not taking a beta blocker. %HRR, Max-PPHR%, and HRR were related to New York Heart Association class and correlated with pVo2. There was no difference in the slopes relating heart rate to pVo2 between patients with and those without chronotropic incompetence (6.1 (1.7) v 5.1 (1.8), p = 0.34). During an average 2.8 year follow up 40 patients (17%) died. In Cox proportional hazard models, pVo2 was the most powerful predictor of survival and neither measure of chronotropic incompetence independently predicted outcome. CONCLUSIONS: pVo2 is a powerful marker of prognosis for patients with CHF whether they are taking beta blockers or not. A low heart rate response to exercise in patients with CHF correlates with worse exercise tolerance but is unlikely to contribute to exercise impairment.

Exercise capacity and cardiac function assessed by tissue Doppler imaging in chronic heart failure.

OBJECTIVE: To examine the relation between longitudinal left ventricular function assessed by tissue Doppler imaging (TDi) and exercise capacity in heart failure. SUBJECTS: 153 patients with chronic heart failure from left ventricular systolic dysfunction (ejection fraction < 45%) and 87 age and sex matched controls. METHODS: Echocardiography was used to measure conventional indices of left ventricular systolic function. TDi was used to assess left and right ventricular longitudinal function by measuring mitral and lateral tricuspid annular velocities during the cardiac cycle. Velocities measured at each point were the systolic peak (S(m)) and the diastolic troughs (E(m) and A(m)), corresponding to passive and active (atrial) left ventricular filling. Each patient also underwent treadmill exercise testing with metabolic gas exchange measurements. RESULTS: Left and right ventricular TDi velocities were greater in controls than in patients. Left ventricular ejection fraction (LVEF) correlated with S(m) (r = 0.30, p = 0.0005), but not with E(m), A(m), or the E(m)/A(m) ratio. There were no significant differences between New York Heart Association (NYHA) functional class for any of the TDi variables. Right ventricular indices were not related to exercise capacity. Systolic myocardial motion measured by TDi correlated more closely with peak oxygen consumption (pVO2) (r = 0.35, p < 0.0001) than LVEF (r = 0.21, p < 0.02). The E(m)/A(m) ratio was not correlated with pVO2. In multiple regression, S(m) was the only left ventricular TDi variable to predict exercise capacity independently (p < 0.05). CONCLUSIONS: Exercise capacity and symptoms are poorly related to conventional measures of cardiac function and more closely correlated with indices of longitudinal left ventricular function as assessed by TDi.

The effects of alpha and beta blockade on ventilatory responses to exercise in chronic heart failure.

OBJECTIVE: To assess the influence of acute alpha and beta blockade on ventilation and symptoms of breathlessness during exercise in patients with chronic heart failure and in controls. METHODS: 11 patients with chronic heart failure and 11 control subjects underwent repeated exercise testing with metabolic gas exchange after random, double blind administration of either an alpha blocker and placebo, a beta blocker and a placebo, both an alpha blocker and a beta blocker, or double placebo. RESULTS: Patients had a lower peak oxygen consumption (mean (SD) 20.7 (4.9) v 37.6 (9.6) ml/kg/min, p < 0.0001) and a steeper slope relating ventilation to carbon dioxide production (VE/CO2 slope) (26.5 (4.1) v 37.1 (8.2), p = 0.0011), than controls. Blood pressure was lower following alpha and beta blockade (p < 0.05) and the gradients of the slopes relating heart rate to oxygen consumption following the beta blocker were reduced (p < 0.05). Exercise time and peak ventilatory variables following beta or alpha blockers were unchanged. Ventilation was reduced during submaximal exercise following the active medications. Combined alpha and beta blockade produced the greatest difference (p < 0.005), but the alpha and beta blockers alone also reduced ventilation (p < 0.05). There was no difference in perceived exertion during exercise with any of the treatments. CONCLUSION: Acute sympathetic inhibition can reduce submaximal ventilation during exercise in patients with heart failure and control subjects, suggesting that autonomic nervous system activation has an important role in the abnormal ventilatory response to exercise in chronic heart failure.

Pattern of ventilation during exercise in chronic heart failure.

OBJECTIVE: To determine the pattern of the abnormal ventilatory response in heart failure and how it relates to symptoms by looking at tidal volume (VT) and frequency (f) during exercise. METHODS: 45 patients with heart failure and 21 controls underwent maximal treadmill based exercise testing with metabolic gas exchange analysis. The relation of ventilation (VE) to VT was plotted to look for an inflection point where VT failed to increase further. The slope of the relation before this inflection point was documented. Time to the inflection point, VT, and f at the inflection point were recorded. The relation of symptom scores to f and E was also examined. RESULTS: Peak oxygen consumption (PVO2) (mean (SD)) was lower (19.7 (4.5) v 37.9 (8.6) ml/kg/min; p < 0001) and the ventilation to carbon dioxide production (VE/VCO2) slope was steeper (40.0 (6.5) v 26.0 (1.6); p < 0.0001) in patients with heart failure than in the control group. The patients reached the inflection point of the VE/VT slope sooner during exercise than the controls (271 (110) v 502 (196) seconds; p < 0.0001). Patients had a higher f and a smaller VT at that point and throughout exercise until the peak where f was the same for patients and controls. VT at the inflection point correlated with PVO2 (r = 0.67; p < 0.0001). Despite having an increased sensation of breathlessness for a given E, patients were less symptomatic of f than controls. CONCLUSIONS: Patients with heart failure breathe at a higher f throughout exercise, reaching an apparent maximal VT earlier. The VT at an inflection point on the VE/VT slope predicts PVO2.

Effect of age and sex on left atrial morphology and function.

AIMS: Left atrial function is abnormal in a wide range of cardiac diseases. This study was designed to assess the effects of normal ageing and sex on left atrial morphology and function. METHODS AND RESULTS: Echocardiography was performed in 123 subjects (age 57 +/- 19 years, range 22 to 89 years, 59 women) with no evidence of cardiovascular disease. M-mode derived left atrial size, B-mode derived left atrial maximal and minimal volumes, and the volume at onset of atrial systole (P-volume) were measured. Left atrial filling, active and passive emptying volumes and ejections fractions, and expansion index were calculated. Subjects were divided into four groups according to age. Left atrial diameter increased with age, with significantly smaller left atrial size in younger subjects. The oldest subjects had significantly higher (P<0.05) left atrial minimal, maximal and P-volume indices. Filling volume index was highest in the oldest subjects (21.9 +/- 5.6 ml/m(2)). Passive emptying volume index was the lowest in those of middle age (10.5 +/- 2.8 ml/m(2)). Active emptying volume index progressively increased with age (P<0.001). Left atrial expansion index and active emptying fraction were not different between the age groups. There was significant difference in passive emptying fraction (P<0.001) with highest values in the youngest (44.7 +/- 7.3%) and lowest values in the oldest subjects (33.6+/-5.4%). CONCLUSIONS: Age- and sex-related reference values of echocardiographic indices of left atrial morphology and function are reported. Ageing is associated with left atrial dilatation. Left atrial conduit function deteriorates with age while reservoir and pump function are maintained. Left atrial anteroposterior diameter is smaller in women than in men, but overall left atrial function is not influenced by sex.