Central and peripheral quadriceps fatigue in congestive heart failure

Abstract

AimsThe clinical syndrome of heart failure includes exercise limitation that is not directly linked to measures of cardiac function. Quadriceps fatigability may be an important component of this and this may arise from peripheral or central factors.Methods and resultsWe studied 10 men with CHF and 10 healthy age-matched controls. Compared with a rest condition, 10 min after incremental maximal cycle exercise, twitch quadriceps force in response to supramaximal magnetic femoral nerve stimulation fell in both groups (CHF 14.1% ± 18.1%, p = 0.037; Control: 20.8 ± 11.0%, p < 0.001; no significant difference between groups). There was no significant change in quadriceps maximum voluntary contraction voluntary force. The difference in the motor evoked potential (MEP) response to transcranial magnetic stimulation of the motor cortex between rest and exercise conditions at 10 min, normalised to the peripheral action potential, also fell significantly in both groups (CHF: 27.3 ± 38.7%, p = 0.037; Control: 41.1 ± 47.7%, p = 0.024). However, the fall in MEP was sustained for a longer period in controls than in patients (p = 0.048).ConclusionsThe quadriceps is more susceptible to fatigue, with a similar fall in TwQ occurring in CHF patients at lower levels of exercise. This is associated with no change in voluntary activation but a lesser degree of depression of quadriceps motor evoked potential.

An Official American Thoracic Society/European Respiratory Society Statement: Update on Limb Muscle Dysfunction in Chronic Obstructive Pulmonary Disease

“…Enhanced muscle fatigability can also occur when the left ventricular function is compromised (267,430). This may be relevant in the subset of patients with COPD (431), including those with cardiac comorbidities (432) and those with pulmonary hypertension (433), in whom altered cardiac output and oxygen delivery have been reported.…”

“…With this technique, the stimulation is applied on the motor cortex through the skull of the patient, allowing the stimulus to travel through the whole path of neuronal discharge. Outcomes of this test are AMERICAN THORACIC SOCIETY DOCUMENTS based on EMG recordings: latency time in milliseconds and motor evoked potentials in microvolts assessed by surface EMG (430).…”

Pathology of the peripheral circulation in chronic heart failure

“…Установлено, что сердечный индекс лишь на ранних ýтапах разви-тия ХСН (I-II функциональный класс) является основным показателем гемодинамики, определя-ющим функциональный статус пациентов. Про-грессирование сердечной недостаточности до III-IV функционального класса ассоциируется с уменьшением зависимости аýробной способ-ности больных от состояния центральной гемо-динамики и повышением роли расстройств пери-ферического кровообращения в определении их физического статуса [21,[31][32][33][34]. Не случайно В.Х.…”

New device for nonvolitional evaluation of quadriceps force in ventilated patients

“…For instance, the force of thumb adduction elicited by ulnar‐nerve stimulation has been used to quantify upper extremity weakness in critically ill patients . The force of knee extension elicited by femoral‐nerve stimulation (quadriceps twitch force) has been used to quantify weakness and fatigue of the quadriceps muscle in different patient groups . Quantification of quadriceps function in critically ill patients is of particular interest because biopsies of this muscle can be obtained easily …”

“…6,9 The force of knee extension elicited by femoral-nerve stimulation (quadriceps twitch force) has been used to quantify weakness and fatigue of the quadriceps muscle in different patient groups. 11,12 Quantification of quadriceps function in critically ill patients is of particular interest because biopsies of this muscle can be obtained easily. [13][14][15] Two setups are used to measure quadriceps twitch force: dangling the leg at the edge of a modified gurney 16 or resting the leg on a right-angle trapezoid support ( Fig.…”