Intercostal and forearm muscle deoxygenation during respiratory fatigue in patients with heart failure: potential role of a respiratory muscle metaboreflex

The purpose of this study was to determine the effect of respiratory muscle fatigue on intercostal and forearm muscle perfusion and oxygenation in patients with heart failure. Five clinically stable heart failure patients with respiratory muscle weakness (age, 66±12 years; left ventricle ejection fraction, 34±3%) and nine matched healthy controls underwent a respiratory muscle fatigue protocol, breathing against a fixed resistance at 60% of their maximal inspiratory pressure for as long as they could sustain the predetermined inspiratory pressure. Intercostal and forearm muscle blood volume and oxygenation were continuously monitored by near-infrared spectroscopy with transducers placed on the seventh left intercostal space and the left forearm. Data were compared by two-way ANOVA and Bonferroni correction. Respiratory fatigue occurred at 5.1±1.3 min in heart failure patients and at 9.3±1.4 min in controls (P<0.05), but perceived effort, changes in heart rate, and in systolic blood pressure were similar between groups (P>0.05). Respiratory fatigue in heart failure reduced intercostal and forearm muscle blood volume (P<0.05) along with decreased tissue oxygenation both in intercostal (heart failure, -2.6±1.6%; controls, +1.6±0.5%; P<0.05) and in forearm muscles (heart failure, -4.5±0.5%; controls, +0.5±0.8%; P<0.05). These results suggest that respiratory fatigue in patients with heart failure causes an oxygen demand/delivery mismatch in respiratory muscles, probably leading to a reflex reduction in peripheral limb muscle perfusion, featuring a respiratory metaboreflex.

Intercostal and forearm muscle deoxygenation during respiratory fatigue in patients with heart failure: potential role of a respiratory muscle metaboreflex.

The purpose of this study was to determine the effect of respiratory muscle fatigue on intercostal and forearm muscle perfusion and oxygenation in patients with heart failure. Five clinically stable heart failure patients with respiratory muscle weakness (age, 66 ± 12 years; left ventricle ejection fraction, 34 ± 3%) and nine matched healthy controls underwent a respiratory muscle fatigue protocol, breathing against a fixed resistance at 60% of their maximal inspiratory pressure for as long as they could sustain the predetermined inspiratory pressure. Intercostal and forearm muscle blood volume and oxygenation were continuously monitored by near-infrared spectroscopy with transducers placed on the seventh left intercostal space and the left forearm. Data were compared by two-way ANOVA and Bonferroni correction. Respiratory fatigue occurred at 5.1 ± 1.3 min in heart failure patients and at 9.3 ± 1.4 min in controls (P<0.05), but perceived effort, changes in heart rate, and in systolic blood pressure were similar between groups (P>0.05). Respiratory fatigue in heart failure reduced intercostal and forearm muscle blood volume (P<0.05) along with decreased tissue oxygenation both in intercostal (heart failure, -2.6 ± 1.6%; controls, +1.6 ± 0.5%; P<0.05) and in forearm muscles (heart failure, -4.5 ± 0.5%; controls, +0.5 ± 0.8%; P<0.05). These results suggest that respiratory fatigue in patients with heart failure causes an oxygen demand/delivery mismatch in respiratory muscles, probably leading to a reflex reduction in peripheral limb muscle perfusion, featuring a respiratory metaboreflex.

Use of propranolol in heart failure patients: safety, tolerability, and effects on left ventricular function.

INTRODUCTION AND OBJECTIVES: Beta-blockers have been shown to improve prognosis in patients with heart failure (HF). Propranolol, which is a low-cost drug, has not been fully studied in this setting. We sought to determine the safety, tolerability and effects on left ventricular function observed with the use of propranolol in HF patients, in functional class II-IV of the New York Heart Association. POPULATION AND METHODS: Prospective study in which 20 outpatients (10 male, mean age 56 +/- 12 years, ranging from 20 to 70) were included. Mean left ventricular ejection fraction (EF) was 28%. Safety, tolerability and effects on electrocardiographic and echocardiographic variables were analyzed. Patients were evaluated in three steps: a) Step I--optimization on conventional drugs and assessment of baseline parameters; b) Step II--start of propranolol (10-20 mg/day), increasing the dose weekly to achieve a heart rate of 60 bpm, or a maximum daily dose of 120 mg; c) Step III--reappraisal of the parameters analyzed in step I, after 3 months of propranolol treatment. RESULTS: On average, after treatment with propranolol, EF increased by 52% (p = 0.0003), E wave deceleration time was prolonged by 62% (p = 0.001) and effective ventricular filling time increased by 38.5% (p = 0.0005). Two patients developed mild congestion which was controlled by increasing diuretic doses, with no need to interrupt the protocol. Four patients had bradycardia-related symptoms, controlled by reducing digoxin doses. Nine subjects developed hyperkalemia, reversed by interrupting or reducing spironolactone. CONCLUSION: Propranolol was safe and well tolerated, and had beneficial effects on ventricular function in HF patients. Its impact on mortality requires further study.

Effects of propranolol on the QT dispersion in congestive heart failure.

OBJECTIVE: Studies have shown that therapy with beta-blockers reduces mortality in patients with heart failure. However, there are no studies describing the effects of propranolol on the QT dispersion in this population. The objective of this study was to assess the electrophysiological profile, mainly QT dispersion, of patients with heart failure regularly using propranolol. METHODS: Fifteen patients with heart failure and using propranolol were assessed over a period of 12 months. Twelve-lead electrocardiograms (ECG) were recorded prior to the onset of beta-blocker therapy and after 3 months of drug use. RESULTS: A significant reduction in heart rate, in QT dispersion and in QTc dispersion was observed, as was also an increase in the PR interval and in the QT interval, after the use of propranolol in an average dosage of 100 mg/day. CONCLUSION: Reduction in QT dispersion in patients with heart failure using propranolol may explain the reduction in the risk of sudden cardiac death with beta-blocker therapy, in this specific group of patients.

Effects of propranolol on the QT dispersion in congestive heart failure.

OBJECTIVE - Studies have shown that therapy with beta-blockers reduces mortality in patients with heart failure. However, there are no studies describing the effects of propranolol on the QT dispersion in this population. The objective of this study was to assess the electrophysiological profile, mainly QT dispersion, of patients with heart failure regularly using propranolol. METHODS - Fifteen patients with heart failure and using propranolol were assessed over a period of 12 months. Twelve-lead electrocardiograms (ECG) were recorded prior to the onset of beta-blocker therapy and after 3 months of drug use. RESULTS - A significant reduction in heart rate, in QT dispersion and in QTc dispersion was observed, as was also an increase in the PR interval and in the QT interval, after the use of propranolol in an average dosage of 100 mg/day. CONCLUSION - Reduction in QT dispersion in patients with heart failure using propranolol may explain the reduction in the risk of sudden cardiac death with beta-blocker therapy, in this specific group of patients.

[Hospital outcome and short-term follow-up of elderly patients presenting to the emergency unit with congestive heart failure]. / Evolução intra-hospitalar e seguimento pós-alta de pacientes idosos atendidos com insuficiência cardíaca congestiva na unidade de emergência.

PURPOSE: To evaluate the in-hospital (IH) outcome and the short-term follow-up of predominantly elderly patients presenting to an emergency room (ER) with congestive heart failure (CHF). METHODS: In an 11 month period, 57 patients presenting to the ER with CHF were included. Mean age was 69 +/- 15 years (27 to 94) and 39 (68.4%) were male. CHF diagnosis was based on the Boston criteria. We evaluated IH outcome and prognosis in a mean follow-up of 5.7 +/- 2.7 months (1 to 12). In addition, some mortality predictors and mechanisms of death according on the ACME system were identified. RESULTS: Eight patients (14%) died in the IH period. Modes of death were circulatory failure (CF) in 7, and peri-operative (PO) in one (aortic valve replacement). During follow-up 9 deaths occurred. Five were due to CF, 2 were sudden and 2 were PO (mitral valve replacement and ventriculectomy). Six-months and 1-year survival rates of the patients who were discharged were 82% and 66%, respectively. Sodium lower than 135 mEq/l (p = 0.004) and female gender (p = 0.038) were independent predictors of mortality. CONCLUSION: Elderly patients with CHF admitted to the ER have high in-hospital and short-term follow up mortalities. The majority die from CF due to worsening heart failure.

Evoluçäo intra-hospitalar e seguimento pós-alta de pacientes idosos atendidos com insuficiência cardíaca congestiva na unidade de emergência / Hospital outcome and short-term follow-up of predominatly elderly patients presenting to the emergency department with congestive heart failure

OBJETIVO - Conhecer a evoluçäo intra-hospitalar (IH) e pós-alta (PA) de uma populaçäo predominantemente idosa, com insuficiência cardíaca congestiva (ICC) na unidade de emergência (UE). MÉTODOS - Durante 11 meses, foram selecionados 57 pacientes consecutivos com ICC, atendidos em UE, com idade média de 69ñ15 (27 a 94) anos, sendo 39 (68,4 por cento) homens. O diagnóstico de ICC baseou-se nos critérios de Boston. Avaliou-se a evoluçäo IH e PA num período médio de 5,7ñ2,7 (1 A 12) meses, procurando-se identificar variáveis que se correlacionassem com a mortalidade e o mecanismo de morte, avaliado pelo sistema ACME. RESULTADOS - Oito (14 por cento) pacientes faleceram na fase IH, sendo 7 por falência circulatória (FC), e 1 em pós-operatório (PO). Durante o seguimento ocorreram 9 (18,4 por cento) óbitos, sendo 5 por FC, 2 mortes súbitas e 2 em (troca valvar mitral e ventriculectomia). A sobrevida dos pacientes...

[Complete atrioventricular block in Kearns-Sayre syndrome]. / Bloqueio atrioventricular total em síndrome de Kearns-Sayre.

A thirty-three year old woman, known to have Kearns-Sayre syndrome for eight years, had an ECG pattern of right bundle branch block and left anterior fascicular block that evolved to complete atrioventricular block, leading her to a syncopal episode. A temporary pacemaker and a permanent one were installed. The patient has been asymptomatic so far.

[Sudden death in patient with right bundle branch block and persistent ST segment elevation]. / Morte súbita em paciente com bloqueio de ramo direito e elevação persistente de segmento ST.

A 43 year old man was admitted to the hospital due to a syncopal episode and presented on the electrocardiogram a pattern of right bundle branch block (RBBB) associated with ST segment elevation from V1 to V4 and normal QT interval. Acute myocardial infarction was suspected but was not confirmed by laboratorial findings. Coronary arteriography was performed and revealed no obstructive disease. No sign suggesting structural heart disease was found. He remained asymptomatic but persisted with RBBB and ST segment elevation. He was discharged from the hospital and was referred to investigation for cardiac arrhythmia as an outpatient, but died suddenly two days later.

[Ablation therapy of type I atrial flutter with radiofrequency]. / Terapia ablativa do flutter atrial tipo I com radiofreqüência.

PURPOSE--To present initial experience on radiofrequency (RF) ablation of atrial flutter (AFL) guided by anatomic and electrophysiologic parameters. METHODS--Eight patients (six males), mean-age of 42 +/- 17.5 years with chronic type I AFL (mean cycle length of 251 +/- 14.3 msec, range 240 to 280 msec) were undergone to RF catheter ablation applied between inferior vena cava (IVC) and tricuspid annulus (TA). Two had persistent and two the paroxysmal form. Two had surgical corrected congenital heart disease (atrial septal defect in 2 and ventricular septal defect in 1). Four had systolic dysfunction and 2, an atrial tachycardia associated with the AFL. RESULTS--Areas of slow conduction represented by fractionated potentials were recorded between IVC and TA in all patients. RF ablation was successful in 8/8 patients (100%). The mean number of RF applications was 9.2 +/- 6.2 (4-24). The successful ablation site was located in the isthmus between IVC and TA in seven patients and in the lateral wall in the patient with ASD. Successful sites had an early atrial activation preceding the atrial electrogram (range from -65 to -82 ms). In one patient the RF energy was successfully delivered between the atriotomy scar (AS) and IVC. After three months follow-up six remained free of recurrent AFL. One pt had type 1 AFL recurrence and one with ASD had a type II AFL. The Type II AFL was successfully ablated between AS and IVC. CONCLUSION--Fractionated potentials were commonly observed between IVC and T; AFL ablation can be guided by anatomic landmarks or electrophysiologic parameters; electrograms recorded at successful sites were early and never fractionated; the long-term evaluation must be analyzed prospectively.

Importância clínica da indicaçäo prococe da terapêutica ablativa em pacientes com Síndrome de Wolf-Parkinson-White e fibrilaçäo atrial com ou sem parada cardio-respiratório / The clinical relevance of early indication of radiofrequency catheter ablation in patientes with Wolff-Parkinson-White Syndrome and atrial fibrilation with or wilhout cardiac arrest

Problema: Vias anômalas com período refratário anterógrado curto, representar um risco de morte súbita em pacientes portadores de Síndrome de Wolff-Parkinson-White. Métodos: De um total de 120 pacientes (pts) portadores de uma conexäo anômala (CA) atrioventricular, 42 pts foram submetidos a ablaçäo com radiofrequência. Desse total, quatro pts do sexo masculino (Grupo 1) com idade média de 37 +/_ 8,6 (27-50) anos que evoluíram para parada cardio-respiratória (PCR) após episódio de fibrilaçäo atrial A) com respostas ventricular rápida foram comparados com 31 pts portadores de vias anômalas manifestas (Grupo 2). Os episódios de PCR ocorreram por administraçäo indevida de verapamil venoso ou betabloqueador oral durante as crises de FA. Após recuperaçäo do quadro de PCR os pts foram submetidos a estudo eletrofisiológico e concominante ablaçäo via cateter com radiofrequência. Foram comparadas também os pacientes do grupo 1 com os pacientes do grupo 2 apresentaram crise de FA porém sem PCR (Grupo 3). Reutados: Todos os pacientes apresentaram pelo menos um episódio de FA durante o procedimento e necessitam cardioversäo elétrica. A médida da capacidade de conduçäo da CA avaliada pelo menor intervalo RR durante FA induzida no grupo(1) de PCR variou de 185 +/_ 25 ms (n=4) contra 253 +/_ 55 ms (n=31) no grupo 2 (p=0,018). A média do menor intervalo RR no grupo 1 variou de 185 +/_ 25 ms contra 212 +/_ 26 ms (n=9) no grupo 3 (p=0,058). Três pacientes com PCR apresentam uma localizaçäo da via anômala em pardepostero-lateral esquerda e um em parede anterolateral esquerda. A ablaçäo foi realizada em ritmo sinusal em pacientes e durante FA em 1 (4 episódios de FA durante a ablaçäo). Durante o FA o parâmetro utilizado para omapeamento foi a presença do eletrograma "V" mais precoce. Os pacientes do G1 encontram-se assintomáticos após um acompanhamento médio de 10,5 meses. Conclusäo: 1-Pacientes portadores de síndrome de WPW e FA com período refratário efetivo curto devem ser encaminhados precocemente para ablaäo.2-Todo paciente com WPW deve ser comunicado da contra-indicaçäo do uso de drogas de açäo exclusivamente no nó. AV. 3-A ablaçäo pode serf realizada durante FA baseando-se na presença da depolarizaçäo "V" endocavitária mais precose em relaçào ao complexo "QRS" do ECG de superfície.

[Catheter ablation in patients with refractory cardiac arrhythmias with radiofrequency techniques]. / Ablação por cateter em pacientes com arritmias cardíacas refratárias utilizando técnicas de radiofreqüência.

PURPOSE: evaluate the efficacy of radiofrequency catheter ablation in patients with refractory cardiac arrhythmias. METHODS: twenty patients with refractory cardiac arrhythmias were undertaken to electrophysiologic studies for diagnosis and radiofrequency catheter ablation of their reentrant arrhythmias. Ten patients were men and 10 women with ages varying from 13 to 76 years (mean = 42.4 years). Nineteen patients had supraventricular tachyarrhythmias: One patient had atrial tachycardia and 1 atrial fibrillation with rapid ventricular rate, 5 patients had reentrant nodal tachycardia, 12 patients had reentrant atrioventricular tachycardia and 1 patient had right ventricular outflow tract tachycardia. RESULTS: the mean time of the procedure was 4.1 hours. The radiofrequency current energy applied was 40-50 V for 30-40 seconds. Ablation was successful in 18/20 (90%) patients; in 15/18 (83%) of successfully treated patients the same study was done for diagnosis and radiofrequency ablation. One patient had femoral arterial occlusion and was treated with no significant sequelae. During a mean follow-up of 4 months no preexcitation or reentrant tachycardia occurred. CONCLUSIONS: the results of our experience with radiofrequency catheter ablation of cardiac arrhythmias suggest that this technique can benefit an important number of patients with cardiac arrhythmias.