Asunto(s)
Muerte Súbita Cardíaca/prevención & control , Desfibriladores Implantables , Taquicardia Ventricular/terapia , Muerte Súbita Cardíaca/epidemiología , Muerte Súbita Cardíaca/etiología , Humanos , Incidencia , Selección de Paciente , Tasa de Supervivencia , Taquicardia Ventricular/complicaciones , Taquicardia Ventricular/mortalidadRESUMEN
BACKGROUND: A variety of mapping criteria have been proposed to localize critical sites at which radiofrequency (RF) can predictably terminate reentrant ventricular tachycardia (VT) caused by coronary artery disease. The purpose of this study was to determine the accuracy of using a combination of 3 mapping criteria in predicting termination of VT by a single RF lesion. METHODS AND RESULTS: Fifteen consecutive patients with coronary artery disease and recurrent sustained VT underwent an attempted RF ablation of 20 monomorphic VTs. Successful termination of VT by a single RF lesion was predicted if all the following mapping criteria were met: (1) an exact QRS match in the 12-lead ECG during entrainment; (2) a return cycle length =10 ms of the VT cycle length; (3) presystolic potentials (<70% of VT cycle length) with an activation time to the QRS within 10 ms of the stimulus to QRS. Inability to meet these 3 criteria was considered to predict failure of VT termination by RF energy at that site. RF ablation was applied to 44 left ventricular sites in 20 VTs at which at least 1 of the mapping criteria was met. VT was terminated with a single RF lesion in 19 of 19 sites meeting all criteria; RF failed to terminate VT at 24 of 25 sites at which all 3 criteria were not met (P<0.0005). CONCLUSIONS: To maximize success and minimize the number of RF lesions in patients with infarct-related VT, all the above 3 mapping criteria should be met before the application of RF energy.
Asunto(s)
Ablación por Catéter , Enfermedad Coronaria/complicaciones , Taquicardia Ventricular/cirugía , Adulto , Anciano , Electrocardiografía , Femenino , Estudios de Seguimiento , Humanos , Masculino , Persona de Mediana EdadRESUMEN
Predischarge testing of implantable cardioverter-defibrillators is often used to tailor antitachycardia pacing algorithms based on the response of induced ventricular tachycardia (VT) to pacing. Despite this practice, little is known about the relation between VT induced at predischarge study and VT that occurs spontaneously. To clarify this relation, we identified 19 patients with VT induced at predischarge study and compared the characteristics of the induced VT with the first episode of spontaneous VT. VT morphology, tachycardia cycle length, and response to antitachycardia pacing were measured from far-field electrograms stored by the implantable cardioverter-defibrillator. All subjects had coronary artery disease and previous myocardial infarction. The mean time from baseline study until a spontaneous VT episode was 162+/-121 days. Analysis of far-field electrograms revealed that spontaneous VT was morphologically different from predischarge-induced VT in 13 of 19 cases (68%). The cycle length of induced VT was significantly shorter than spontaneous VT when VT morphologies were different but not when spontaneous and induced VT had an identical morphology. Antitachycardia pacing was effective in terminating 18 of 19 (95%) induced VTs and 14 of 18 (78%) spontaneous VTs. Antitachycardia pacing was effective in terminating 9 of 12 episodes of morphologically different spontaneous VTs and 5 of 6 episodes of morphologically identical spontaneous VTs (p = NS). Thus, the characteristics of VT induced at predischarge study correlate poorly with those of subsequent spontaneous VT episodes due to the induction of faster "nonclinical" VTs at predischarge testing. This may limit the applicability of predischarge testing in tailoring antitachycardia pacing algorithms.
Asunto(s)
Desfibriladores Implantables , Electrocardiografía , Taquicardia Ventricular/fisiopatología , Taquicardia Ventricular/terapia , Algoritmos , Enfermedad Coronaria/complicaciones , Enfermedad Coronaria/fisiopatología , Procesamiento Automatizado de Datos , Estudios de Seguimiento , Frecuencia Cardíaca , Humanos , Masculino , Pronóstico , Recurrencia , Taquicardia Ventricular/complicacionesRESUMEN
INTRODUCTION: For relatively slow monomorphic ventricular tachycardia (VT) after myocardial infarction, entrainment can be used to identify reentry circuit "isthmus sites" (exit sites and sites proximal to the exit) where radiofrequency (RF) catheter ablation has the greatest likelihood of interrupting reentry. Similarities in coronary and ventricular anatomy may cause such sites to form in preferential locations. The objective of this study is to determine if there are preferential locations for reentry circuit isthmus regions in chronic inferior wall infarctions causing VT. METHODS AND RESULTS: Catheter mapping and RF catheter ablation was performed in 21 patients with an old inferior wall myocardial infarction and VT. The inferior wall was divided into 9 anatomic regions: 3 apical, 3 mid, and 3 basal segments. Of 46 different VTs, an endocardial isthmus site was identified in one or more zones in 28 (61%), with 10 VTs having isthmus sites in two or more adjacent regions. Isthmus zones were found in a basal region of the left ventricle in 24 (86%) of 28 VTs, in a mid segment in 9 (32%) VTs, and in an apical segment in 1 (4%) (P = 0.002). Of 30 RF current applications that terminated VT, 21 (70%) were at basal isthmus sites. CONCLUSION: The high prevalence of endocardial isthmus zones near the base of the left ventricle suggests that the mitral annulus often plays a role in defining the margins of reentry circuits that cause relatively slow VTs after inferior wall myocardial infarction.
Asunto(s)
Infarto del Miocardio/fisiopatología , Taquicardia Ventricular/fisiopatología , Anciano , Ablación por Catéter , Electrocardiografía , Humanos , Persona de Mediana Edad , Infarto del Miocardio/complicaciones , Taquicardia Ventricular/etiología , Taquicardia Ventricular/cirugíaRESUMEN
INTRODUCTION: During entrainment of reentrant ventricular tachycardia (VT), the difference between the postpacing interval (PPI) and the VT cycle length (VTCL) measured at the pacing site is an indication of the conduction time from the pacing site to the reentry circuit. The difference is usually < or = 30 msec at successful ablation sites. However, electrical noise during pacing sometimes obscures the electrograms recorded directly from the pacing site. The objective of this study is to determine if the PPI-VTCL difference measured at the mapping catheter electrodes proximal to the stimulating electrode accurately predicts the PPI-VTCL difference at the stimulating electrode. METHODS AND RESULTS: Endocardial catheter mapping was performed in 26 patients with infarct-related VT. At 191 sites during 56 VTs, unipolar pacing from the distal electrode entrained VT and electrograms recorded from the mapping catheter were discernable following pacing in both the bipolar recordings from the distal electrode pair (BI 1-2) and the electrode pair 6 mm proximal to the distal electrode (BI 3-4). The PPI-VTCL difference at BI 1-2 correlated well with that measured at BI 3-4 (r = 0.88, P = 0.001). A PPI-VTCL difference at BI 3-4 < or = 30 msec predicted a PPI-VTCL difference at BI 1-2 < or = 30 msec with a sensitivity of 95%, specificity of 87 %, and predictive accuracy of 91%. CONCLUSIONS: Measurement of the PPI from electrodes proximal to the stimulating electrode is a reasonable alternative when the PPI cannot be assessed from the pacing electrode.
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Cateterismo Cardíaco/métodos , Infarto del Miocardio/fisiopatología , Taquicardia Ventricular/etiología , Taquicardia Ventricular/fisiopatología , Anciano , Cateterismo Cardíaco/instrumentación , Electrocardiografía , Femenino , Humanos , Masculino , Persona de Mediana Edad , Infarto del Miocardio/complicacionesRESUMEN
A 49-year-old obese female was admitted for acute onset pleuritic chest pain. Previous history was significant for surgical correction of a lower esophageal ring. Echocardiography revealed a pericardial effusion, which resolved with steroids. One week later, the patient complained of similar symptoms. Physical examination was consistent with tamponade, while a Hammond crunch was noted over the sternum. Chest x-ray revealed a pneumopericardium. Operative findings consisted of an intrathoracic stomach, a greater curvature ulcer that had perforated the pericardium and a mediastinal abscess. A pericardial window was created, a drain was placed and the perforated ulcer was repaired. Postoperative course was complicated by fever and gastrointestinal bleeding. The patient died suddenly on the 30th postoperative day. Autopsy revealed a massive pulmonary embolus, bleeding esophageal ulcer, healed gastric ulcer and serofibrinous pericarditis. This case illustrates that, while the immediate treatment of tension pyopneumopericardium is usually successful, postoperative mortality remains elevated.
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Taponamiento Cardíaco/etiología , Úlcera Péptica Perforada/complicaciones , Neumopericardio/etiología , Úlcera Gástrica/complicaciones , Resultado Fatal , Femenino , Humanos , Persona de Mediana Edad , Úlcera Péptica Perforada/etiología , Estómago/anomalías , SupuraciónRESUMEN
OBJECTIVE: To determine the intra- and interobserver reproducibility of Doppler-derived ascending aortic flow velocity measurements at rest and during upright exercise of increasing intensity; and to determine the relationship between Doppler-derived measurements and cardiac output obtained by the indirect Fick carbon dioxide rebreathing method in the same conditions. SUBJECTS: Twenty young healthy adults participated in the study; eight participated in the first part and 12 in the second. DESIGN: For the intra-observer study, subjects were submitted to three workloads (50, 100 and 150 W) of 5 mins duration on two occasions, seven days apart. The intra-observer reproducibility was determined by two technicians taking the Doppler measurements within 90 s during the steady state of each workload during the first session. The relationship between cardiac output and aortic flow velocities was studied by measuring cardiac output by carbon dioxide rebreathing and flow velocities by continuous wave Doppler ultrasound simultaneously at rest as well as during the last minute of the three workloads (50, 100 and 150 W) of 5 mins duration. RESULTS: The interobserver reproducibility was very good, with r values of 0.87 for peak velocity (PV) and 0.97 for peak acceleration (PA). The intra-observer reproducibility at the seventh day interval showed r values of 0.93 for PV and 0.96 for PA for one of the technicians. PV and PA of the ascending aortic flow correlated well with cardiac output (r = 0.85 and 0.82, respectively, P < 0.01). ANOVA showed that PV and PA increase proportionately with exercise intensity. CONCLUSION: PV and PA of ascending aortic flow are reproducible and reflect changes in left ventricular function during exercise.
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Aorta/fisiología , Velocidad del Flujo Sanguíneo , Gasto Cardíaco , Ejercicio Físico/fisiología , Función Ventricular Izquierda/fisiología , Adolescente , Adulto , Aorta/diagnóstico por imagen , Femenino , Humanos , Masculino , Variaciones Dependientes del Observador , Reproducibilidad de los Resultados , Ultrasonografía DopplerRESUMEN
Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia in clinical practice, and is responsible for considerable morbidity. Basic studies have shown that AF is usually due to the coexistence of multiple functional atrial re-entry circuits, and that the main determinant of its haemodynamic manifestations is the ventricular response rate. The major adverse clinical consequences of AF include palpitations, impaired cardiac function and thromboembolism. One approach to treating AF is to convert the patient's cardiac rhythm to sinus rhythm by direct current electrical cardioversion, which is initially successful in about 90% of cases. However, the AF recurrence rate over the year subsequent to cardioversion is very high, in the order of 75% in patients receiving no drug therapy. Class I and class III antiarrhythmic drugs reduce the rate of recurrence of AF, but at the expense of a variety of potential adverse effects including ventricular proarrhythmia. The latter is a rare effect (occurring in 1 to 2% of patients receiving most drugs), but can be lethal. A second approach to therapy is to leave the patient in AF, but to control the ventricular response rate and to prevent thromboemboli with oral anticoagulants. Disadvantages of this approach include the possibilities of functional limitations imposed by the arrhythmia, adverse effects of drug therapy, and major bleeding related to anticoagulation. New approaches currently under study include surgery to prevent AF from sustaining itself, implantable cardioverter devices to maintain sinus rhythm, and modification of AV nodal function by the induction of controlled radiofrequency injury.
Asunto(s)
Antiarrítmicos/uso terapéutico , Fibrilación Atrial/terapia , Animales , Anticoagulantes/uso terapéutico , Fibrilación Atrial/tratamiento farmacológico , Fibrilación Atrial/fisiopatología , Electrofisiología , HumanosRESUMEN
We report a patient with drug and hyperthermia induced rhabdomyolysis who developed acute renal failure. During the oliguric phase of 22 days, there was profound hypocalcemia (lowest ionized calcium of 0.34 mmol/l), associated with appropriately elevated intact PTH levels and high normal 1,25(OH)2D levels. Massive calcification in necrotic muscle occurred during this time. In the recovery phase, hypercalcemia was present lasting 33 days (maximum ionized calcium of 1.99 mmol/L), associated with suppression of PTH secretion, low 1,25(OH)2D3 levels, decreased bone resorption and mobilization of the muscle calcium deposits. This case report illustrates that the changes in serum calcium in rhabdomyolysis-associated acute renal failure are explicable by the deposition or removal of mineral into or from necrotic muscle with the parathyroid and vitamin D changes occurring secondarily.
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Lesión Renal Aguda/etiología , Calcio/metabolismo , Rabdomiólisis/complicaciones , Lesión Renal Aguda/metabolismo , Adulto , Calcinosis/etiología , Desipramina/envenenamiento , Dihidroxicolecalciferoles/metabolismo , Femenino , Humanos , Hipercalcemia/etiología , Hipocalcemia/etiología , Músculos/metabolismo , Músculos/patología , Hormona Paratiroidea/metabolismo , Rabdomiólisis/inducido químicamente , Rabdomiólisis/metabolismoRESUMEN
To examine the relative risk of transmission of the human immuno-deficiency virus (HIV) through bites and scratches, we studied 198 health care workers, 30 of whom were traumatized in this fashion while caring for an aggressive AIDS patient. This violent patient frequently bit or scratched others, his mouth had blood and saliva, while his fingernails were at times soiled with semen, feces, and urine. He was HIV antibody and antigen positive. Although HIV was recovered from his peripheral blood lymphocytes, after 2.5 years of serial follow-up, all traumatized personnel were clinically normal, no HIV was cultured from their blood, and all were HIV antibody and P24 antigen negative. We conclude that this viremic AIDS patient, while producing copious amounts of body fluids, failed to infect those caring for him through bites and scratches. The risk of transmission of HIV through this route under similar conditions should be low.