RESUMO
OBJECTIVE: To identify perioperative clinical predictors of permanent pacemaker implantation following aortic valve replacement. DESIGN AND PATIENTS: Prospective cohort study on 276 patients submitted for aortic valve replacement: 267 patients (mean (SD) age, 57.5 (14) years) with no conduction disturbances, and nine patients (67.7 (5) years) with severe conduction disturbances requiring permanent pacing; 65 perioperative variables (38 preoperative, eight intraoperative, and 19 postoperative) were considered. RESULTS: Nine patients (3.2%) had irreversible second or third degree atrioventricular (AV) block requiring permanent pacing. Risk factors for permanent pacing identified by univariate analysis were: preoperative: additional valvar disease, aortic regurgitation, myocardial infarction, pulmonary hypertension, anaemia, use of digitalis; intraoperative: cardiac arrest; postoperative: cardiac arrest, conduction disturbances, electrolytic imbalance, angiotensin converting enzyme inhibitor use. Multivariate logistic regression analysis identified preoperative aortic regurgitation (p < 0.005; odds ratio (OR) 6.6, 95% confidence interval (CI) 1.6 to 12.2), myocardial infarction (p < 0.0005; OR 15.2, 95% CI 6.3 to 19.9), pulmonary hypertension (p < 0.005; OR 12.5, 95% CI 3.2 to 18.3), and postoperative electrolyte imbalance (p < 0.01; OR 4.5, 95% CI 1.3 to 6.4). CONCLUSIONS: Irreversible AV block requiring permanent pacemaker implantation is an uncommon condition following aortic valve replacement. Previous aortic regurgitation, myocardial infarction, pulmonary hypertension, and postoperative electrolyte imbalance should be considered in order to identify patients at increased risk for advanced AV block.
Assuntos
Valva Aórtica/cirurgia , Bloqueio Cardíaco/terapia , Implante de Prótese de Valva Cardíaca/efeitos adversos , Marca-Passo Artificial , Idoso , Insuficiência da Valva Aórtica/cirurgia , Estenose da Valva Aórtica/cirurgia , Arritmias Cardíacas/etiologia , Bradicardia/etiologia , Estudos de Coortes , Feminino , Bloqueio Cardíaco/etiologia , Próteses Valvulares Cardíacas , Humanos , Masculino , Pessoa de Meia-Idade , Cuidados Pós-Operatórios/métodos , Estudos Prospectivos , Análise de Regressão , Fatores de RiscoAssuntos
Taquicardia Ectópica de Junção/congênito , Adolescente , Amiodarona/uso terapêutico , Antiarrítmicos/uso terapêutico , Criança , Digoxina/uso terapêutico , Quimioterapia Combinada , Feminino , Humanos , Masculino , Propafenona/uso terapêutico , Taquicardia Ectópica de Junção/tratamento farmacológicoRESUMO
The aim of the study was to evaluate by Doppler tissue imaging (DTI) the combined effects of atrio-ventricular (AV) delay and heart rate (HR) changes on global and segmental right (RV) and left (LV) ventricular diastolic function in 15 patients with dual-chamber pacemakers paced in the DDD mode. RV and LV inflow velocities and regional systolic and diastolic pulsed-wave (PW) DTI parameters were analyzed at four different pacing modes: (1) HR 70 beats/min, AV delay 125 ms; (2) HR 70 beats/min, AV delay 188 ms; (3) HR 89 beats/min, AV delay 125 ms; (4) HR 89 beats/min, AV delay 188 ms. For each pacing mode selected, RV diastolic filling velocities always prevailed over LV ones. As for RV and LV adaptation to the four different stimulation protocols, a higher paced rate and a prolonged AV delay caused across both the AV valves a decrease of E wave and of E/A ratios. The intersegmental comparison of PW-DTI parameters outlined that RV free wall exhibited significantly higher peak systolic (Sm) and early-diastolic (Em) wall velocities, and longer systolic ejection time. Considering separately RV and LV segmental physiology at the four programmed pacing modes, an increase in HR determined a progressive shortening of systolic ejection times in all the segments analyzed. Moreover, in each region the Em/Am ratio decreased with higher HR and longer AV delay. Conversely, Em encountered a progressive reduction in RV free wall, while remaining quite unchanged in all the LV regions. Both ventricles shared a similar pattern of global and regional adaptation to programmed HR and AV delay modifications, consisting in a progressive greater contribution of late diastole to ventricular filling at higher HR and more prolonged AV delay. However, at a regional level the right ventricle exhibited higher systolic and diastolic wall velocities than all left ventricular regions.
Assuntos
Arritmias Cardíacas/diagnóstico por imagem , Arritmias Cardíacas/terapia , Estimulação Cardíaca Artificial , Ecocardiografia Doppler , Função Ventricular Esquerda/fisiologia , Função Ventricular Direita/fisiologia , Idoso , Análise de Variância , Arritmias Cardíacas/fisiopatologia , Nó Atrioventricular/diagnóstico por imagem , Nó Atrioventricular/fisiopatologia , Velocidade do Fluxo Sanguíneo/fisiologia , Diástole/fisiologia , Feminino , Frequência Cardíaca/fisiologia , Ventrículos do Coração/diagnóstico por imagem , Humanos , Masculino , Pessoa de Meia-IdadeRESUMO
BACKGROUND: Atrial fibrillation (AF) is the most frequently encountered arrhythmic complication associated with cardiac surgery. The aim of this paper was to identify the clinical predictors of AF occurrence following aortic valve replacement. METHODS: Three hundred and two patients were included in this study and divided into two groups according to the absence (SR group, 243 patients, mean age 55.6 +/- 15 years) or the evidence (AF group, 59 patients, mean age 63.8 +/- 11 years) of post-aortic valve replacement AF. Sixty-five perioperative variables (37 preoperative, 8 intraoperative and 20 postoperative) were considered. RESULTS: Post-aortic valve replacement paroxysmal AF occurred in 59 out of 302 patients (19%). At univariate analysis, post-aortic valve replacement AF was associated with advanced age, left atrial enlargement, preoperative episodes of paroxysmal AF, the use of a warm blood cardioplegic solution and normothermia, administration of inotropic agents, prolonged assisted ventilation but also with postoperative acidosis, electrolyte imbalance and atrioventricular and intraventricular conduction disorders. Stepwise forward multivariate logistic regression analysis identified age (p = 0.002, odds ratio--OR 1.04), left atrial enlargement (p = 0.004, OR 2.6), a prior history of paroxysmal AF (p = 0.0003, OR 10.9), and postoperative electrolyte imbalance (p = 0.01, OR 2.3) as independent correlates of AF, whereas the use of hypothermia appeared to be a protective factor (p = 0.0004, OR 0.26). CONCLUSIONS: According to our findings, post-aortic valve replacement AF seems to be associated with well-defined anatomical and electrical substrates generated by advanced age, increased left atrial dimensions, and a possible electrical remodeling consequent to prior repetitive episodes of paroxysmal AF. On these grounds, external factors such as postoperative electrolyte imbalance might enhance atrial ectopic activity and trigger postoperative sustained tachyarrhythmias, while the use of hypothermia might allow for better protection of the atrial myocardium against intraoperative ischemia.
Assuntos
Valva Aórtica/cirurgia , Fibrilação Atrial/etiologia , Doenças das Valvas Cardíacas/cirurgia , Complicações Pós-Operatórias , Análise de Variância , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Fatores de RiscoRESUMO
Acute myocardial infarction is an uncommon complication in pregnant women. The case of a 30-years-old patient who suffered of an acute myocardial infarction during the first trimester of pregnancy, with secondary development of left ventricular aneurysm is presented. She had a sudden death 3 months after delivery, while waiting for coronary arteriography.
Assuntos
Aneurisma Cardíaco/etiologia , Infarto do Miocárdio/complicações , Complicações Cardiovasculares na Gravidez , Adulto , Evolução Fatal , Feminino , Ventrículos do Coração , Humanos , GravidezRESUMO
Tetralogy of Fallot is the most common form of cyanotic congenital heart disease. Measurement of physical activity is usually performed as a routine part of the patient's cardiac evaluation. The aim of this study was to examine the exercise performance of young patients operated on for tetralogy of Fallot, assessing the possible influence of known negative prognostic factors related to the surgical repair. The study group comprised 41 consecutive patients (29 male and 12 female, ages 11.2 +/- 3.9 years, range 6-16 years) operated on for tetralogy of Fallot. Patients in the study group were divided in subgroups in relation to the age of surgical intervention (before or after 2 years of life), the surgical approach (combined transatrial/transpulmonary approach or right ventriculotomy), and the presence of aortopulmonary shunts prior to performing total correction. Their data were compared with those of 33 aged-matched asymptomatic control subjects (19 male and 14 female, ages 11.9 +/- 1.3 years, range 11-16 years). Blood pressure and heart rate measured at rest were similar between control and Fallot groups. A normal increase in systolic blood pressure was observed in response to exercise intensity for all subgroups. No significant difference between control and Fallot groups was found under conditions of mild or moderate exercise or for diastolic blood pressure at rest and in response to exercise. Lower maximal heart rate and systolic blood pressure values were recorded in all patients when compared with the control subjects. Significant differences in peak workload were detected between control and Fallot groups and between the control and each subgroup; however, no difference was found between subgroups. In conclusion, despite their very satisfactory clinical status, all patients showed a reduced peak workload, irrespective of the surgical approach, age at surgery, and aortopulmonary shunts prior to performing total correction.
Assuntos
Tolerância ao Exercício , Tetralogia de Fallot/fisiopatologia , Adolescente , Criança , Eletrocardiografia , Teste de Esforço , Feminino , Hemodinâmica , Humanos , Masculino , Período Pós-Operatório , Tetralogia de Fallot/cirurgiaRESUMO
The perioperative factors potentially associated with post-coronary artery bypass grafting (CABG) ventricular tachyarrhythmias (VT) onset have not been deeply investigated. Monomorphic or polymorphic ventricular tachycardia and ventricular fibrillation represent the most dreadful arrhythmic events that can complicate the postoperative course of CABG. As a consequence, the aim of our paper was to identify which perioperative variables might predict post-CABG VT occurrence. One hundred and fifty-two consecutive patients who underwent CABG surgery at our Institution were included in the study. Post-CABG VT occurred in 13 out of 152 patients (8.5%, six cases of monomorphic ventricular tachycardia and seven cases of ventricular fibrillation). At univariate analysis, VT patients were significantly younger (54.8+/-6.6 vs. 60.1+/-8.8, P=0.038), exhibited a more severe coronary artery disease (CAD) (number of diseased vessels 2.92+/-0.3 vs. 2.45+/-0.7, P=0.023, and percentage of patients with three-vessel CAD 91.7% vs. 57.3%, P=0.043) and received a greater number of CABGs than those remaining in sinus rhythm (SR) (percentage of patients receiving three or more CABGs 76. 9% vs. 38.8%, P1000 76.9% vs. 38%, Pnormal range 72.7% vs. 30.7%, P=0.014), electrolyte derangement (84.6% vs. 45.6%, P=0.017) and a severe haemodynamic impairment (need for IABP 23% vs. 2.9%, P1000, postoperative electrolyte imbalance, the need for three or more CABGs and of IABP all were independent correlates for VT. In conclusion, post-CABG VT seem to be related to the preexistence of a severe underlying coronary artery disease along with perioperative triggering factors such as acute ischemia, electrolytic disorders and a sudden haemodynamic impairment.
Assuntos
Ponte de Artéria Coronária , Complicações Pós-Operatórias/prevenção & controle , Taquicardia Ventricular/prevenção & controle , Causalidade , Estudos de Coortes , Feminino , Humanos , Itália/epidemiologia , Modelos Logísticos , Masculino , Pessoa de Meia-Idade , Análise Multivariada , Razão de Chances , Complicações Pós-Operatórias/epidemiologia , Taquicardia Ventricular/epidemiologia , Taquicardia Ventricular/etiologiaRESUMO
OBJECTIVE: Atrial fibrillation (AF) is the most frequently encountered arrhythmic complication associated with coronary surgery. The aim of this paper was then to identify the clinical predictors of post-CABG AF occurrence. METHODS: 150 consecutive patients were included in this study and divided into two groups according to the absence (SR group, 104 male and 22 female, age 58.4+/-8.8 years) or presence (AF group, 23 male and 1 female, age 65.4+/-6.3 years) of post-CABG AF. Forty-seven perioperative variables were considered. RESULTS: After univariate analysis, advanced age (SR vs. AF: 58.4+/-8.8 vs. 65.4+/-6.3, P < 0.001), an increased BMI (SR vs. AF: 26.1+/-2.7 vs. 27.4+/-2.5, P = 0.026), a prior history of paroxysmal AF (SR vs. AF: 3.2% vs. 16.7%, P = 0.028), left atrial enlargement (SR vs. AF: 21.1% vs. 70.8%, P < 0.001) and a more severe coronary artery disease (CAD) (SR vs. AF: no. of diseased vessels: 2.42+/-0.7 vs. 2.91+/-0.3, P = 0.001; three-vessel CAD (54.1% vs. 91.3%, P = 0.002) were the only factors that statistically differed between the groups. Multivariate logistic regression analysis identified left atrial enlargement (P < 0.0001), a prior history of paroxysmal AF (P = 0.007) and a more severe CAD (P = 0.0047) to be independent correlates for AF. CONCLUSIONS: Post-CABG AF seems to require a well definite anatomical and electrical substrate that is generated by increased left atrial dimensions, a greater extension of coronary lesions and a possible electrical remodeling consequent to prior repetitive episodes of paroxysmal AF.
Assuntos
Fibrilação Atrial/etiologia , Ponte de Artéria Coronária/efeitos adversos , Fatores Etários , Idoso , Fibrilação Atrial/diagnóstico , Fibrilação Atrial/epidemiologia , Índice de Massa Corporal , Ponte Cardiopulmonar/efeitos adversos , Doença das Coronárias/diagnóstico , Doença das Coronárias/cirurgia , Ecocardiografia , Eletrocardiografia , Feminino , Mortalidade Hospitalar , Humanos , Incidência , Masculino , Pessoa de Meia-Idade , Valor Preditivo dos Testes , Estudos Retrospectivos , Fatores de Risco , Índice de Gravidade de Doença , Taquicardia Paroxística/diagnóstico , Taquicardia Paroxística/epidemiologia , Taquicardia Paroxística/etiologiaRESUMO
Idiopathic left ventricular tachycardia is a rare arrhythmia whose electrophysiological basis is not yet well-defined. We report a case of idiopathic left ventricular tachycardia caused by a reentrant circuit limited exclusively to the two fascicles of the left bundle branch.
Assuntos
Fascículo Atrioventricular/fisiopatologia , Taquicardia Paroxística/diagnóstico , Taquicardia Ventricular/diagnóstico , Adulto , Estimulação Cardíaca Artificial , Erros de Diagnóstico , Eletrocardiografia , Humanos , Masculino , Taquicardia Paroxística/fisiopatologia , Taquicardia Supraventricular/diagnóstico , Taquicardia Ventricular/fisiopatologiaRESUMO
Ventricular repolarization analysis has been shown to be effective in the identification of electrical myocardial instability leading to ventricular arrhythmias. The aim of the present study was to examine ventricular repolarization time indexes, in terms of both absolute measures and dispersion across the myocardium, in young patients with repaired tetralogy of Fallot (41 pts; 28M/13F, age 11.7+/-3.6 years), assessing, furthermore, the possible influence of known negative prognostic factors relative to the surgical operation and residual haemodynamic abnormalities. The data of the study group were compared with those of 33 aged-matched asymptomatic control subjects (22M/11F, age 11.7+/-2.3 years). Ventricular depolarisation, as expressed by QRS duration, resulted significantly longer in total Fallot group than in the Control group (P<0.0001). Particularly, patients operated through a right ventricular approach showed higher values of QRS interval (P<0.0001) than those operated through a combined transatrial-transpulmonary approach. All the patients operated on for tetralogy of Fallot exhibit, with respect to control subjects, an inhomogeneous prolongation of ventricular repolarization across the myocardium, as showed by the significant increase in the absolute indexes of ventricular repolarization, JTc (P<0.001), QT (P<0.0001) and QTc (P<0.0001) with a concomitant prolongation of the indexes of dispersion of ventricular recovery time, QTcD (P<0.0001), JTcD (P<0.0001), 'adjusted' QTcD (P<0.001) and Tp-Te interval (P<0.0001). A temporal and regional variation in the ventricular repolarization across the myocardium in patients with repaired tetralogy of Fallot, could create the pathophysiological substrate for an increased cardiac electrical instability. The presence of negative prognostic factors, relative to the surgical intervention or residual haemodynamic abnormalities, even if not influencing the arrhythmic substrate, invariably present, could determine 'trigger' conditions essential for the development of ventricular arrhythmias.
Assuntos
Eletrocardiografia , Tetralogia de Fallot/fisiopatologia , Função Ventricular , Adolescente , Arritmias Cardíacas/etiologia , Estudos de Casos e Controles , Criança , Pré-Escolar , Eletrofisiologia , Feminino , Seguimentos , Humanos , Masculino , Tetralogia de Fallot/complicações , Tetralogia de Fallot/cirurgiaRESUMO
Sustained ventricular tachyarrhythmias (VT), such as monomorphic or polymorphic ventricular tachycardia, and ventricular fibrillation, represent the most serious arrhythmic events that can complicate the postoperative course of coronary artery bypass grafting (CABG). The perioperative factors potentially associated with post-CABG sustained VT onset have not been thoroughly investigated. As a consequence, the aim of our study was to identify which perioperative variables might predict post-CABG VT occurrence. One hundred and fifty-two consecutive patients who underwent CABG surgery at our Institute were included in the study. Post-CABG VT occurred in 13 out of 152 patients (8.5%, six cases of monomorphic ventricular tachycardia and seven cases of ventricular fibrillation). Univariate analysis revealed that VT patients were significantly younger (54.8 +/- 6.6 vs 60.1 +/- 8.8, P = 0.038), exhibited more severe coronary artery disease (CAD) (no. of diseased vessels, 2.92 +/- 0.3 vs 2.45 +/- 0.7, P = 0.023; and percentage of patients with three-vessel CAD, 91.7 vs 57.3%, P = 0.043), and received a greater number of CABGs than those remaining in sinus rhythm (SR) (percentage of patients receiving three or more CABGs, 76.9 vs 38.8%, P = 0.018) Moreover, VT patients more frequently developed intra- or postoperative myocardial infarction (total CK > 1,000, 76.9 vs 38%, P = 0.016; and MB-CK > normal range, 72.7 vs 30.7%, P = 0.014), electrolyte derangement (84.6 vs 45.6%, P = 0.017), and a severe hemodynamic impairment (need for intra-aortic balloon pump (IABP), 23 vs 2.9%, P = 0.009). On multivariate analysis, total CK > 1,000, postoperative electrolyte imbalance, the need for three or more CABGs, and for IABP all were independent correlates for VT. In conclusion, post-CABG VT seem to be related to the preexistence of a severe underlying coronary artery disease along with perioperative triggering factors, such as acute ischemia, electrolytic disorders, and sudden hemodynamic impairment.
Assuntos
Ponte de Artéria Coronária , Complicações Pós-Operatórias/prevenção & controle , Taquicardia Ventricular/prevenção & controle , Fibrilação Ventricular/prevenção & controle , Ponte de Artéria Coronária/métodos , Doença das Coronárias/complicações , Doença das Coronárias/cirurgia , Feminino , Humanos , Modelos Logísticos , Masculino , Pessoa de Meia-Idade , Análise Multivariada , Razão de Chances , Assistência Perioperatória , Fatores de Risco , Índice de Gravidade de DoençaRESUMO
Atrial fibrillation is the most common cardiac rhythm disorder associated with hospitalization. Two therapeutic options have been available: antiarrhythmic drug therapy, and external or internal electrical cardioversion. Electrical cardioversion of atrial fibrillation remains one of the most widely used and effective treatments for the restoration of normal sinus rhythm. However, many patients continue to receive an antiarrhythmic drug before and after cardioversion in an attempt either to cardiovert the arrhythmia chemically or to maintain sinus rhythm after successful cardioversion. Because some pharmacological agents can affect the cardioversion procedure for atrial fibrillation or flutter, and because many patients with such arrhythmias may require electrical cardioversion when they are taking antiarrhythmic drugs, the question of a possible effect of drug therapy on the efficacy and safety of electrical cardioversion of atrial fibrillation arises. Early reports of direct current cardioversion provoking potentially lethal ventricular arrhythmias raised suspicions of an arrhythmogenic role for digoxin antiarrhythmic therapy, and it is customary to withhold these drugs for 24 to 48 h before cardioversion is attempted. However, this complication is likely to arise only in patients who are close to, or actually manifesting, signs of drug toxicity. On the other hand, treatment with therapeutic concentrations of antiarrhythmic drugs before cardioversion may in some cases be associated with a significant reduction in the number of shocks and decreased energy required to restore sinus rhythm, a lower incidence of postshock arrhythmias and a reduced risk of early recurrence of atrial fibrillation.
Assuntos
Antiarrítmicos/farmacologia , Fibrilação Atrial/terapia , Cardioversão Elétrica , Amiodarona/efeitos adversos , Amiodarona/farmacologia , Antiarrítmicos/intoxicação , Fibrilação Atrial/tratamento farmacológico , Terapia Combinada , Digoxina/farmacologia , Digoxina/intoxicação , Cardioversão Elétrica/efeitos adversos , Flecainida/efeitos adversos , Flecainida/farmacologia , Humanos , Procainamida/efeitos adversos , Procainamida/farmacologia , Quinidina/efeitos adversos , Quinidina/farmacologia , Verapamil/efeitos adversos , Verapamil/farmacologiaRESUMO
Antiarrhythmic drugs are known to affect the depolarization and repolarization time in a different fashion. The aim of the present study was to compare the effects of Sotalol, Flecainide and Propafenone on some common (QT, QTc, JT, JTc) or uncommon (QTc dispersion, T-peak to T-end interval) electrocardiographic parameters in order to evaluate the effects of these antiarrhythmic drugs on ventricular repolarization time both in terms of absolute values and of dispersion across the myocardium. The analysis of these antiarrhythmic drug effects was performed on the standard 12-lead electrocardiograms of 31 patients (17F and 14M, age 38.1+/-17 years, range 11-67 years) in the free-drug state and at the steady state after oral treatment with Sotalol (160 mg daily), Flecainide (200 mg daily) and Propafenone (450 mg daily). These drugs were prescribed, separately, to all the 31 patients, free of underlying structural heart disease, for the treatment of their atrio-ventricular nodal re-entry tachycardia. Data of the present study show that Sotalol, over the range prescribed, significantly prolongs ventricular repolarization index QT (P=0.001), JT (P=0.0001) and JTc (P=0.0001) values in an homogeneous fashion, as shown by the significant decrease in QTcD (P=0.019) and Tp-Te (P=0.01). On the contrary, Flecainide treatment was associated with an increase in QTcD (P=0.029), Tp-Te (0.0001), QT (P=0.001), QTc (P=0.0001) and QRS (P=0.0001), with no significant changes in JT and JTc. Propafenone, over the range prescribed, did not affect repolarization time, resulting only in a prolongation of depolarization time as expressed by the increase of QRS (P=0.0001).
Assuntos
Antiarrítmicos/farmacologia , Flecainida/farmacologia , Sistema de Condução Cardíaco/efeitos dos fármacos , Propafenona/farmacologia , Sotalol/farmacologia , Função Ventricular , Adolescente , Adulto , Idoso , Criança , Eletrocardiografia , Feminino , Humanos , Masculino , Pessoa de Meia-IdadeRESUMO
BACKGROUND: Intraventricular conduction disturbances determine complete impairment of impulse propagation along the right or left bundle branch or the two left fascicles. HYPOTHESIS: This study was undertaken to investigate the electrophysiologic significance of QRS axis (QRSA) orientation in bifascicular and trifascicular blocks. METHODS: A group of 76 subjects, 43 with right bundle-branch block (RBBB) and left anterior hemiblock (LAH) (Group A), and 33 with left bundle-branch block (LBBB) (Group B), was submitted to electrophysiologic evaluation. RESULTS: In Group A, QRSA was inversely related only to intraventricular conduction, while in Group B, QRSA inversely related to infrahisal conduction times. A value of < -60 degrees was considered the cut-off point for determining subjects with a considerable leftward QRSA deviation. Of the 27 Group A patients with a QRSA < -60 degrees, 38.5% developed an infrahisal second-degree atrioventricular (AV) block during incremental atrial stimulation (IAS) in comparison with 11.1% of those with QRSA > -60 degrees. Of the 9 Group B patients with a QRSA < -60 degrees, 44.4% exhibited severe impairment of infrahisal conduction at baseline and 66.6% developed an infrahisal second-degree AV block during IAS, whereas among the remaining 24 with a QRSA > -60 degrees, in only 8.3% were both infrahisal (HV1 and HV2) intervals dangerously prolonged, and 23.8% encountered an infrahisal second-degree AV block during IAS. In Group A, atrioventricular conduction time > 200 ms exhibited a better predictive accuracy than QRSA < -60 degrees for the development of an infrahisal second-degree AV block during IAS, whereas the latter appeared the best noninvasive predictor in Group B with a slightly lesser predictive accuracy than HV > 80 ms. CONCLUSION: The degree of leftward QRSA deviation seems to reflect the entity of intraventricular conduction delay in patients with RBBB + LAH, while it appears to be directly related to infrahisal conduction prolongation in those with LBBB.
Assuntos
Eletrocardiografia , Bloqueio Cardíaco/diagnóstico , Sistema de Condução Cardíaco/fisiopatologia , Idoso , Bloqueio de Ramo/diagnóstico , Bloqueio de Ramo/fisiopatologia , Estimulação Cardíaca Artificial , Estudos de Casos e Controles , Feminino , Bloqueio Cardíaco/fisiopatologia , Humanos , MasculinoRESUMO
Malignant ventricular arrhythmias have been reported in patients with repaired tetralogy of Fallot. The aim of this study was to examine ventricular repolarization time indexes, in terms of both absolute measures and dispersion across the myocardium, in young patients operated on for tetralogy of Fallot (32 patients; 19 males and 13 females, mean age 11.1 +/- 3.4 years); these electrocardiographic parameters have been shown to be effective in the identification of electrical myocardial instability and hence of risk for ventricular arrhythmias too. The electrocardiographic data of the study group were compared with those of 22 age-matched asymptomatic control subjects (14 males and 8 females, mean age 12 +/- 1.5 years). Furthermore it has also been investigated the possible influence on ventricular repolarization of known negative prognostic factors relative to the surgical approach, age at intervention, and presence of pulmonary obstruction and/or regurgitation. No patients in the study group revealed at the Holter recordings and/or at the exercise test severe ventricular arrhythmias. From the analysis of ventricular depolarization, expressed by QRS duration, emerged that it resulted significantly longer in total Fallot group (p < 0.0001), and in each subgroup (p < 0.05) compared to the control group. Particularly, patients operated through a right ventricular approach showed higher values of QRS interval (p < 0.05) than those operated through combined transatrial-transpulmonary approach. All patients operated on for tetralogy of Fallot showed, compared to control subjects, a non homogeneous prolongation of ventricular repolarization across the myocardium, as confirmed by the significant increase in the absolute indexes of ventricular repolarization, JTc (p < 0.001), QT (p < 0.0001) and QTc (p < 0.0001) with a concomitant prolongation of the indexes of dispersion of ventricular recovery time, QTc dispersion (p < 0.0001), JTc dispersion (p < 0.0001), "adjusted" QTc dispersion (p < 0.05) and T peak-T end interval (p < 0.0001). The non homogeneous ventricular repolarization across the myocardium, preceding the development of arrhythmic events, could be the effect of the right ventricular morphological and functional changes of tetralogy of Fallot predisposing to the development of ventricular reentry tachyarrhythmias.
Assuntos
Tetralogia de Fallot/cirurgia , Adolescente , Arritmias Cardíacas/etiologia , Criança , Morte Súbita Cardíaca/etiologia , Eletrocardiografia , Feminino , Ventrículos do Coração/fisiopatologia , Humanos , Masculino , Período Pós-Operatório , Prognóstico , Fatores de Risco , Tetralogia de Fallot/mortalidade , Tetralogia de Fallot/patologia , Fatores de TempoRESUMO
Based on our previous experience in doxorubicin-treated patients, in whom we observed a significant increase of ventricular recovery time indexes, we analyzed these non- invasive parameters of myocardium electrical instability in forty-three 5-fluorouracil-treated patients, to test the hypothesis of a mechanoelectrical disarrangement occurring in 5-fluorouracil (5FU) cardiotoxicity. All patients enrolled were studied at the first presentation and following chemotherapy. The study showed the absence of any significant changes in recovery time indexes or in other electrocardiographic parameters. Our data suggest that 5FU does not interfere with electrical properties of myocardial fibers.
Assuntos
Antimetabólitos Antineoplásicos/efeitos adversos , Fluoruracila/efeitos adversos , Ventrículos do Coração/fisiopatologia , Neoplasias/tratamento farmacológico , Função Ventricular/fisiologia , Idoso , Ecocardiografia , Eletrocardiografia , Feminino , Ventrículos do Coração/efeitos dos fármacos , Humanos , Masculino , Pessoa de Meia-Idade , Estadiamento de Neoplasias , Neoplasias/fisiopatologia , Estudos RetrospectivosRESUMO
The aim of our study was to analyze the ventricular repolarization phase in patients with isolated aortic stenosis (AS) in order to search for possible abnormalities that might contribute to an explanation of the electrical instability peculiar to this valve disease. We selected a population of 39 patients with isolated AS (25 M and 14 F, mean age 60+/-16 yrs). As controls we considered a group of 31 age-matched healthy subjects 20 M and 11 F, mean age 55+/-14 yrs, P=NS. Disease severity was assessed by echocardiography, calculating the maximum and mean pressure gradients max and mean PG) and the functional valve orifice area. Various electrocardiographic intervals (QT, QT'c, JT, JTc) and indices (QT and QTc dispersion were adopted for a detailed non-invasive evaluation of the ventricular repolarization. In patients with AS, M-QT (391+/-45 ms vs 362+/-25 ms, P=0.002), M=QTc (431+/-29 ms vs 412+/-19 ms, P=0.003), M-JT (290+/-41 ms vs 265+/-26 ms, P=0.003, M-JTc 331+/-29 ms vs 302+/-19 ms, P<0.001, QTD (67+/-34 ms vs 40+/-15 ms, P<0.001), QTcD (77+/-36 ms vs 52+/-23 ms, P<0.001) all resulted significantly greater than in controls. QTD and QTcD both resulted linearly related either to max PCi (r=0.388, P=0.018 and r=0.357, P=0.03) or to mean PG (r=0.513, P=0.004 and r=0.438, P=0.015), while M-JT and M-JTc turned out to be directly related only to mean PG (r=0.436, P=0.016 and r=0.483, P=0.007). Our findings suggest a prolonged duration of ventricular recovery and a greater dispersion of ventricular repolarization in patients with AS and might account for the electrical instability proper to this valve dysfunction. Besides, the existence of a linear direct relation between the severity of AS and the degree of inhomogeneity of left ventricular recovery, together with the correlation found among mean PCr and the total duration of the repolarization phase, expressed by the intervals JT and JTc, strongly suggest the hypothesis that in AS arrhythmogenic substrates development parallels the worsening of the valve defect.
Assuntos
Estenose da Valva Aórtica/diagnóstico , Estenose da Valva Aórtica/fisiopatologia , Eletrocardiografia , Sistema de Condução Cardíaco/fisiopatologia , Adulto , Idoso , Estenose da Valva Aórtica/diagnóstico por imagem , Ecocardiografia Doppler , Feminino , Humanos , Modelos Lineares , Masculino , Pessoa de Meia-Idade , Prognóstico , Sensibilidade e Especificidade , Índice de Gravidade de DoençaRESUMO
Patients with dilated cardiomyopathy, ventricular volume or pressure overload, or dysynergistic ventricular contraction and relaxation are prone to develop severe ventricular arrhythmias. In these patients it has been suggested that the abnormal mechanics of contraction can disturb 'mechano-electric feedback', also known as 'contraction-excitation feedback', which is defined as the development of electrophysiological changes during or after changes in mechanical loading. This electrical instability, expressed by significant changes in ventricular repolarization and refractoriness and by the development of afterdepolarizations, has been variously reported in isolated tissues and isolated ventricles as well as in hearts in vivo. Furthermore, it is known that many patients with supraventricular tachycardia but otherwise structurally normal hearts can develop atrial fibrillation and that atrial arrhythmias frequently occur in the setting of acute or chronic increases in atrial size and pressure. It is possible that changes in atrial load directly alter the electrophysiological properties of the atrium by an analogue mechanism of contraction-excitation feedback. This paper reviews the literature concerning mechanoelectric feedback involvement in rhythm disorders, with the aim of investigating, through basic and clinical research, the clinical and therapeutic implications.
Assuntos
Displasia Arritmogênica Ventricular Direita , Cardiomiopatias/etiologia , Disfunção Ventricular Direita/fisiopatologia , Cardiomiopatias/fisiopatologia , Retroalimentação , Coração/fisiopatologia , Humanos , Disfunção Ventricular Direita/complicaçõesRESUMO
STUDY POPULATION: Twenty patients without laboratory evidence of cardiac disease who underwent electrophysiological study because of recurrent ventricular tachyarrhythmias. PATIENTS AND METHODS: The study population was divided into two groups: group A (20 patients [six males and 14 females] mean age 42.2 +/- 13 years), with idiopathic ventricular tachycardia (VT), and group B (30 controls [10 males and 20 females] mean age 43.6 +/- 16 years). Noninvasive multiparametric analysis of the ventricular repolarization phase was performed on the standard 12-lead electrocardiogram by using a digitizer connected with a computerized system. The intervals JT, heart rate-corrected JT (JTc), JT apex (JTa), heart rate-corrected JTa (JTac), T apex T end (TaTe) and heart rate-corrected TaTe (TaTec) were measured and considered to be representative of the whole depolarization process. QT dispersions (QTeD) and QTc dispersions (QTecD) were calculated to assess the degree of spatial inhomogeneity of action potential duration. RESULTS: Patients in group A had higher JT (272 +/- 36 ms versus 265 +/- 25 ms, P = 0.01), JTc (336 +/- 28 ms versus 318 +/- 18 ms, P = 0.01), JTa (210 +/- 28 ms versus 185 +/- 28 ms, P = 0.001) and JTac (240 +/- 20 ms versus 215 +/- 13 ms, P < 0.001) values than those of patients in group B, despite shorter TaTe (71 +/- 10 ms versus 90 +/- 18 ms, P < 0.001) and TaTec (88 +/- 12 ms versus 110 +/- 12 ms, P < 0.001). Moreover, QTeD and QTecD were significantly longer in group A than in group B (55 +/- 18 ms versus 42 +/- 19 ms [P = 0.01] and 80 +/- 18 ms versus 55 +/- 28 ms [P = 0.001], respectively). CONCLUSIONS: Patients with idiopathic VT exhibit inhomogeneous prolongation of ventricular repolarization, due to a considerable increase in the initial part in association with a shorter terminal phase, as well as a greater dispersion of ventricular repolarization.
Assuntos
Taquicardia Ventricular/diagnóstico , Adulto , Eletrocardiografia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Razão de Masculinidade , Taquicardia Ventricular/fisiopatologiaRESUMO
We evaluated the arrhythmic profile in a population of 20 Becker muscular dystrophy (BMD) patients searching for possible correlations between the severity of the arrhythmic events, the cardiac autonomic balance (assessed by heart rate variability analysis in the time domain) and the degree of left ventricular systolic impairment. A population of 14 male healthy individuals served as the control group. BMD subjects exhibited lower values of SDNN (P=0.013), SDANN index (P=0.008) and 24-h mean heart rate (P=0.002). The total number of premature ventricular beats (totPVB) and the number of PVB out of 1000 heartbeats (PVB/1000) appeared also higher in BMD subjects (P=0.05 and P=0.046, respectively). No difference was found in terms of 24-h mean QTc and 24-h longest QT among the two groups. TotPVB and PVB/1000 were inversely related to both the ejection fraction (r= -0.620, P=0.004 and r= -0.517, P=0.019) and to the shortening fraction (r= -0.568, P=0.009 and r= -0.469, P=0.037). Twenty-four-h mean QTc was also inversely related to both the ejection fraction (r= -0.520, P=0.019) and the fractional shortening (r= -0.491, P=0.028). These data suggest that in BMD there is cardiac autonomic imbalance characterized by sympathetic predominance and an increased susceptibility to ventricular arrhythmias, even in the absence of overt cardiomyopathy. Furthermore, the severity of the arrhythmic profile in BMD appears closely related to the degree of left ventricular systolic dysfunction.