RESUMO
OBJECTIVES: This study was designed to establish whether left ventricular pseudohypertrophy in cardiac tamponade can be reproducibly induced in an experimental canine model and to investigate the mechanism of its production. BACKGROUND: Past experimental and clinical studies have shown reduction of ventricular volumes resulting from cardiac tamponade. Left ventricular pseudohypertrophy, a transient thickening of myocardial walls, was recently described as a new echocardiographic sign of cardiac tamponade. METHODS: Cardiac tamponade was induced in seven anesthetized open chest dogs with serial bolus injections of 50 ml each of 0.9% saline solution into the pericardial sac. Under hemodynamic monitoring, M-mode and two-dimensional echocardiographic measurements were performed from a right parasternal window at each stage of graded cardiac tamponade. RESULTS: There was a progressive increase of interventricular septal and posterior wall diastolic thickness. Mean wall thickness (interventricular septal thickness + posterior wall thickness divided by 2) was 9.8 +/- 1.3 mm at baseline, 14.3 +/- 0.9 mm at peak tamponade and 9.0 +/- 1.5 mm after fluid withdrawal (p < 0.0001). Mean wall thickness correlated directly with the severity of cardiac tamponade, as estimated from the level of right arterial pressures (r = 0.75 and p < 0.0001), and with the decrease of left ventricular cavity volume (r = -0.67 and p < 0.0001). Left ventricular mass did not change significantly. CONCLUSIONS: Left ventricular pseudohypertrophy is a constant manifestation of cardiac tamponade in a canine model. The degree of myocardial thickening correlates with the reduction of ventricular dimensions and with the severity of hemodynamic compromise, representing a constant facet of heart remodeling in cardiac tamponade.
Assuntos
Tamponamento Cardíaco/complicações , Hipertrofia Ventricular Esquerda/etiologia , Animais , Pressão Sanguínea , Tamponamento Cardíaco/diagnóstico por imagem , Modelos Animais de Doenças , Cães , Ecocardiografia , Frequência Cardíaca , Ventrículos do Coração/patologia , Hipertrofia Ventricular Esquerda/diagnóstico por imagem , Hipertrofia Ventricular Esquerda/patologia , Modelos CardiovascularesRESUMO
OBJECTIVES: This study was performed to examine the effect of intracoronary exogenous basic fibroblast growth factor (bFGF) on angiogenesis in infarcted myocardial regions. BACKGROUND: Exogenous bFGF is a potent promoter of angiogenesis. Little information is available on its effect on myocardial angiogenesis. METHODS: Myocardial infarction was induced in 10 pigs by intracoronary injection of microscopic beads. Four pigs served as a control group; in six pigs slow-release bFGF was delivered by the beads. Cardiac performance was evaluated by repeated echocardiographic measurement and angiogenesis was evaluated by immunohistochemical studies 14 days later. RESULTS: As compared with control pigs, pigs treated with bFGF had higher microvessel counts (mean +/- SEM) in both viable tissue (141 +/- 27 per field vs. 39 +/- 4, p = 0.01) and nonviable tissue (329 +/- 26 per field vs. 95 +/- 7, p < 0.001) within the infarct area. No significant differences in total regional left ventricular wall motion were noted between the two groups throughout the 14-day study period. CONCLUSIONS: In the swine, direct intracoronary application of bFGF to infarcted myocardium enhances myocardial neovascularization within 2 weeks.
Assuntos
Vasos Coronários/efeitos dos fármacos , Fator 2 de Crescimento de Fibroblastos/uso terapêutico , Infarto do Miocárdio/tratamento farmacológico , Animais , Vasos Coronários/patologia , Ecocardiografia , Infarto do Miocárdio/diagnóstico por imagem , Infarto do Miocárdio/patologia , Miocárdio/patologia , Neovascularização Patológica , SuínosRESUMO
OBJECTIVES: To determine the prevalence and clinical significance of early ST segment elevation resolution after primary percutaneous transluminal coronary angioplasty (PTCA) for acute myocardial infarction (AMI). BACKGROUND: Despite angiographically successful restoration of coronary flow early during AMI, adequate myocardial reperfusion might not occur in a substantial portion of the jeopardized myocardium due to microvascular damage. This phenomenon comprises the potentially beneficial effect of early recanalization of the infarct related artery (IRA). METHODS: Included in the study were 117 consecutive patients who underwent angiographically successful [Thrombolysis in Myocardial Infarction (TIMI III)] primary PTCA. The patients were classified based on the presence or absence of reduction > or =50% in ST segment elevation in an ECG performed immediately upon return to the intensive cardiac care unit after the PTCA in comparison with ECG before the intervention. RESULTS: Eighty-nine patients (76%) had early ST segment elevation resolution (Group A) and 28 patients (24%) did not (Group B). Group A and B had similar clinical and hemodynamic features before referring to primary PTCA, as well as similar angiographic results. Despite this, ST segment elevation resolution was associated with better predischarge left ventricular ejection fraction (LVEF) (44.7 +/- 8.0 vs. 38.2 +/- 8.5, p < 0.01). Group B patients, as compared with those of Group A, had a higher incidence of in-hospital mortality (11% vs. 2%, p = 0.088), congestive heart failure (CHF) [28% vs. 19%, odds ratio (OR) = 4, 95% confidence interval (CI) 1 to 15, p = 0.04], higher long-term mortality (OR = 7.3, 95% CI 1.9 to 28, p = 0.004 with Cox proportional hazard regression analysis) and long-term CHF rate (OR = 6.5, 95% CI 1.3 to 33, p = 0.016 with logistic regression). CONCLUSIONS: Absence of early ST segment elevation resolution after angiographically successful primary PTCA identifies patients who are less likely to benefit from the early restoration of flow in the IRA, probably because of microvascular damage and subsequently less myocardial salvage.
Assuntos
Angioplastia Coronária com Balão , Eletrocardiografia , Infarto do Miocárdio/fisiopatologia , Angiografia Coronária , Ecocardiografia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Infarto do Miocárdio/diagnóstico , Infarto do Miocárdio/mortalidade , Infarto do Miocárdio/terapia , Taxa de Sobrevida , Resultado do Tratamento , Função Ventricular EsquerdaRESUMO
Digitalis preparations frequently fail to control heart rate in many patients who have chronic atrial fibrillation, particularly during physical exertion. The effects of orally administered verapamil, 160 to 240 mg/day, on the heart rate at rest and during mild exercise were studied in 23 digitalized patients with chronic atrial fibrillation of various causes. Verapamil substantially reduced the excessive heart rate response to exercise in well-digitalized patients who had chronic atrial fibrillation.
Assuntos
Fibrilação Atrial/tratamento farmacológico , Verapamil/uso terapêutico , Idoso , Doença Crônica , Digoxina/sangue , Digoxina/uso terapêutico , Feminino , Frequência Cardíaca/efeitos dos fármacos , Humanos , Masculino , Pessoa de Meia-Idade , Esforço Físico , Verapamil/farmacologiaRESUMO
Twenty pathologic specimens of heart, each with a cleft in the anterior leaflet of the mitral valve not associated with septal defects of persistent common atrioventricular canal (isolated cleft of the mitral valve), were studied. In 9 cases, there were either no associated anomalies or ones not of functional significance. In each of the other 11 cases there were other significant associated cardiac anomalies, including ventricular septal defect and d-transposition of the great arteries. Functional consequences of the mitral anomaly were mitral insufficiency, subaortic stenosis, or both. Mitral insufficiency was related principally to the width of the cleft. Subaortic stenosis, when present, was due to the position of insertion of accessory chordae in the ventricular septum in a position under the commissure, between the left and right aortic cusps or under the right aortic cusp.
Assuntos
Comunicação Atrioventricular/complicações , Defeitos dos Septos Cardíacos/complicações , Valva Mitral/anormalidades , Adolescente , Adulto , Idoso , Angiografia , Estenose Aórtica Subvalvar/etiologia , Criança , Pré-Escolar , Ecocardiografia , Feminino , Comunicação Interatrial , Humanos , Lactente , Recém-Nascido , Masculino , Pessoa de Meia-Idade , Valva Mitral/anatomia & histologia , Valva Mitral/patologia , Insuficiência da Valva Mitral/etiologia , Estenose da Valva Mitral/etiologiaRESUMO
Nine children with isolated cleft mitral valve, aged 1 day to 12 years, were studied. The electrocardiogram showed a normal QRS axis in 5 subjects. Cardiac catheterization was performed in 4 patients and demonstrated severe mitral insufficiency in 3 but failed to clearly demonstrate a cleft mitral valve or gooseneck deformity. The mitral cleft was confirmed at operation in 2 patients. Two-dimensional echocardiography demonstrated a cleft dividing the anterior mitral leaflet into 2 portions in each patient. The mitral anulus was normally positioned and the atrioventricular septum present. Atrial and ventricular septa were intact. Features similar to anatomic studies such as accessory chordae and thickening of the edges of the cleft with increasing age were also seen. Two-dimensional echocardiography is the only method available to reliably diagnose isolated cleft of the mitral valve.
Assuntos
Ecocardiografia/métodos , Insuficiência da Valva Mitral/congênito , Valva Mitral/fisiopatologia , Cateterismo Cardíaco , Criança , Pré-Escolar , Diástole , Feminino , Humanos , Lactente , Recém-Nascido , Masculino , Valva Mitral/patologia , Insuficiência da Valva Mitral/diagnóstico , Insuficiência da Valva Mitral/cirurgia , SístoleRESUMO
Nitroglycerin (NTG) ointment has been shown to be effective in the treatment of angina pectoris and congestive heart failure. Its duration of action is usually 4 to 6 hours. This study presents data that show that a new slow-release NTG ointment produces hemodynamic improvement over at least 24 hours. Twenty patients with coronary artery disease were tested with serial gated equilibrium radionuclide ventriculography before and at various stages of continuous, once-a-day use of slow-release NTG ointment and 4 days after cessation of therapy. NTG ointment significantly (p less than 0.005) decreased left ventricular end-diastolic and end-systolic volumes both at rest (23% and 33%) and during handgrip exercise (22% and 32%) when examined after continuous usage of at least 24 hours. Ejection fraction increased 21% at rest, from 0.42 +/- 0.15 to 0.51 +/- -0.18, p less than 0.0005). The ratio of peak systolic pressure to end-systolic volume increased 85% at rest (p less than 0.05) and 54% during exercise (p less than 0.01). All values had returned to baseline 4 days after cessation of treatment. Thus, slow-release NTG ointment may be useful in the treatment of angina pectoris and congestive heart failure on a once-a-day basis.
Assuntos
Hemodinâmica/efeitos dos fármacos , Nitroglicerina/administração & dosagem , Idoso , Pressão Sanguínea/efeitos dos fármacos , Volume Cardíaco/efeitos dos fármacos , Preparações de Ação Retardada , Frequência Cardíaca/efeitos dos fármacos , Humanos , Masculino , Pessoa de Meia-Idade , Contração Miocárdica/efeitos dos fármacos , Nitroglicerina/farmacologia , Pomadas , Esforço Físico , Pertecnetato Tc 99m de Sódio , Volume Sistólico/efeitos dos fármacos , Fatores de TempoRESUMO
Impaired relaxation is frequently masked by elevated filling pressures, resulting in a pseudonormal flow pattern (E/A >1.0). Because the E/A wave ratio increases as filling pressures rise, it is generally assumed that patients with an E/A ratio of <1.0 (impaired relaxation pattern) have relatively low filling pressures. Nevertheless, patients with an E/A ratio of <1.0 can have as profoundly elevated filling pressures as patients with a pseudonormal or restrictive filling pattern. Because left ventricular (LV) pressure during end-diastole essentially determines atrial afterload, the response of the A-wave velocity to a reduction of atrial afterload by a standardized Valsalva maneuver should allow estimation of LV end-diastolic pressure (LVEDP) regardless of the baseline Doppler flow pattern. This was tested in 20 consecutive patients who were studied by pulse-wave Doppler echocardiography during cardiac catheterization. There was a close correlation between LVEDP and the change in A-wave velocity during the Valsalva maneuver (r = 0.85, SEE 6.7 mm Hg) regardless of the baseline E/A ratio. In patients with a LVEDP of <15 mm Hg the A wave decreased by 21 +/- 15 cm/s. In patients with a LVEDP of >25 mm Hg the A wave increased by 18 +/- 13 cm/s. The change in the E/A ratio during Valsalva correlated fairly with LVEDP (r = -0.72, SEE 8.8 mm Hg), the baseline E/A ratio correlated poorly, and scatter was substantial (r = 0.46, SEE 11.2 mm Hg). Just as elevated filling pressures can mask impaired relaxation, the impaired relaxation pattern can mask the presence of elevated filling pressures. This can be revealed by testing the response of the A wave to the Valsalva maneuver, allowing estimation of LVEDP independent of the baseline E/A ratio.
Assuntos
Ecocardiografia Doppler de Pulso , Manobra de Valsalva , Pressão Ventricular , Adolescente , Adulto , Idoso , Velocidade do Fluxo Sanguíneo , Cateterismo Cardíaco , Circulação Coronária , Feminino , Humanos , Masculino , Pessoa de Meia-IdadeRESUMO
A selective defect in cardiac conduction in the anterior division of the left bundle branch was induced in a patient by therapy with procainamide hydrochloride. The defect in conduction, when intermittent, resulted in 2:1 Wencklebach sequences and produced a pattern similar to classic electrical alternans. The prognosis in drug-induced alternans is good, and it is important to differentiate it from true electrical alternans.
Assuntos
Bloqueio de Ramo/induzido quimicamente , Procainamida/efeitos adversos , Idoso , Bloqueio de Ramo/fisiopatologia , Eletrocardiografia , Feminino , Humanos , PrognósticoRESUMO
To study the mechanism of altered mitral function in the presence of an isolated cleft mitral valve (ICMV) with regard to the relative roles of the cleft and of the accessory chordae, seven patients with ICMV were studied with color Doppler echocardiography. Mitral insufficiency ranging from mild to severe was demonstrated in six cases. The regurgitant jet originated in each case from the site of the cleft: in five patients the regurgitant jet had a narrow base originating exactly from the cleft; in the sixth patient, the regurgitant flow presented as a broad-based jet suggesting that accessory chordae restricted the motion of the anterior mitral leaflet. Turbulent flow in the left ventricular outflow tract, starting at the level of the accessory chordae, was found in one patient in whom a pressure drop of 44 mm Hg was detected with continuous-wave Doppler imaging. The altered function of the mitral valve cleft stems from two elements, the cleft itself and the accessory chordae. Color Doppler flow imaging showed that the cleft was the main factor causing mitral insufficiency. The accessory chordae played an additional pathogenetic role in two patients by causing restricted mitral motion or left ventricular outflow tract obstruction.
Assuntos
Ecocardiografia Doppler , Valva Mitral/anormalidades , Adolescente , Adulto , Criança , Pré-Escolar , Cordas Tendinosas/anormalidades , Cordas Tendinosas/diagnóstico por imagem , Feminino , Cardiopatias Congênitas/diagnóstico por imagem , Humanos , Lactente , Masculino , Pessoa de Meia-Idade , Valva Mitral/diagnóstico por imagem , Insuficiência da Valva Mitral/diagnóstico por imagem , Insuficiência da Valva Mitral/etiologiaRESUMO
A false aneurysm of the right atrium is described. The false aneurysm appeared after open-heart surgery and was probably related to loosening of a right atrial suture. Because of the low pressure in the right atrium, the danger of rupture seemed to be low, and conservative therapy was chosen.
Assuntos
Aneurisma Cardíaco , Próteses Valvulares Cardíacas/efeitos adversos , Insuficiência da Valva Mitral/cirurgia , Feminino , Aneurisma Cardíaco/diagnóstico , Aneurisma Cardíaco/etiologia , Átrios do Coração , Humanos , Pessoa de Meia-Idade , Deiscência da Ferida Operatória/complicaçõesRESUMO
BACKGROUND: The murmur of hypertrophic obstructive cardiomyopathy (HOCM) increases in intensity in about 80% of those patients in whom carotid sinus pressure (CSP) slows the heart rate. This does not occur in valvular aortic stenosis (AS). STUDY OBJECTIVES, DESIGN, AND PATIENTS: It was hypothesized that left ventricular (LV) obstruction increases with CSP in HOCM and not in AS. Furthermore, it was not clear whether it was the sudden bradycardia or CSP itself that was responsible for the effect noted. Therefore, studies were performed using two different interventions: (1) Doppler echocardiography was performed before and during CSP in 36 HOCM patients and 21 AS patients; (2) two patients with DDD pacemakers and HOCM were examined before and after pacemaker rate slowing. Finally, atrial pacing was performed in three HOCM patients at catheterization, and atrial pacing was either slowed or stopped (without CSP). RESULTS: LV outflow velocity and pressure gradient increased in 28 of 30 HOCM patients (92%) in whom heart rate decreased with CSP. The peak instantaneous pressure gradient increased from 45+/-37 to 77+/-53 mm Hg (p<0.005), and the velocity contour became more typical of HOCM. The pressure gradient increased from 30 mm Hg to 64 and 81 mm Hg, respectively, in the two patients with DDD pacemakers after pacemaker rate slowing. Similar results were seen with slowing or cessation of atrial pacing at catheterization. In contrast, the pressure gradient increased in only three of 21 AS patients (14%), to 44+/-28 from 41+/-25 mm Hg, and remained unchanged in the other 18. CONCLUSION: This study shows that LV outflow velocity and pressure gradient increase markedly in most HOCM patients (92%) if CSP succeeds in slowing the heart rate, but not in patients with valvular AS. A similar effect is obtained by simply decreasing the atrial rate in patients with DDD or atrial pacemakers. This increase in outflow tract obstruction is sufficient to account for the increase in murmur intensity. Decreased afterload (secondary to greater aortic decompression with the longer diastole), increased intrinsic force of contraction with the bradycardia (the Woodworth effect), and Starling's law may play independent roles in the dynamic increase in obstruction observed during CSP in patients with HOCM. Worsening of mitral regurgitation was not clearly shown to contribute to the increase in murmur, but it cannot readily be ruled out.
Assuntos
Estenose da Valva Aórtica/complicações , Pressão Sanguínea , Bradicardia/etiologia , Cardiomiopatia Hipertrófica/complicações , Seio Carotídeo/fisiopatologia , Obstrução do Fluxo Ventricular Externo/complicações , Adulto , Idoso , Idoso de 80 Anos ou mais , Estenose da Valva Aórtica/diagnóstico por imagem , Estenose da Valva Aórtica/fisiopatologia , Velocidade do Fluxo Sanguíneo , Bradicardia/fisiopatologia , Bradicardia/terapia , Estimulação Cardíaca Artificial , Cardiomiopatia Hipertrófica/diagnóstico por imagem , Cardiomiopatia Hipertrófica/fisiopatologia , Seio Carotídeo/diagnóstico por imagem , Ecocardiografia Doppler , Feminino , Frequência Cardíaca , Ventrículos do Coração/diagnóstico por imagem , Ventrículos do Coração/fisiopatologia , Humanos , Masculino , Pessoa de Meia-Idade , Valva Mitral/diagnóstico por imagem , Contração Miocárdica , Obstrução do Fluxo Ventricular Externo/diagnóstico por imagem , Obstrução do Fluxo Ventricular Externo/fisiopatologiaRESUMO
A huge pericardial effusion was diagnosed during fetal ultrasound examination performed in the 42nd week of pregnancy on a healthy 25-year-old woman. Immediately after the birth, a two-dimensional echocardiogram confirmed this finding in the infant, and an intrapericardial kidney-shaped solid mass measuring 45 x 56 x 15 mm, completely surrounded by pericardial effusion, was visualized to the left part of the heart. The heart was normal. No signs of cardiac tamponade were seen. At the age of two days, the mass was surgically resected and the pericardial fluid evacuated. Microscopic examination revealed that the mass was formed totally of normal lung tissue surrounded by normal pleura. To the best of our knowledge, this is the first case of intrapericardial extralobar sequestration consisting of an accessory lung with completely normal lung tissue.
Assuntos
Sequestro Broncopulmonar/patologia , Pericárdio/patologia , Adulto , Sequestro Broncopulmonar/complicações , Feminino , Humanos , Recém-Nascido , Masculino , Derrame Pericárdico/diagnóstico , Derrame Pericárdico/diagnóstico por imagem , Derrame Pericárdico/etiologia , Gravidez , Ultrassonografia Pré-NatalRESUMO
Rotating tourniquets were once part of the traditional treatment of acute pulmonary edema. Their effectiveness has been questioned and vasodilator therapy has replaced them, but early favorable results suggested that they may play a beneficial role. A radioisotope technique was used to evaluate blood volume increments in the leg after venous occlusion at 60 mm Hg in 26 patients with left ventricular dysfunction following myocardial infarction. Mean radionuclide counts (reflecting the blood volume distal to the occlusion) increased from the preocclusion value. Thus, satisfactory trapping of blood is achieved. However, mean left ventricular ejection fraction (EF) decreased slightly but significantly and this decrease in EF was observed in 18 of 26 patients. Left ventricular end-diastolic and end-systolic volume equivalents tended to decrease slightly but not in all patients. Mean stroke volume and cardiac output equivalents were reduced by 14 percent while peripheral resistance increased significantly. The present study thus fails to support the hypothesis that preload reduction by tourniquets improves left ventricular function; the exact opposite effect may occur because of increased afterload.
Assuntos
Volume Sanguíneo , Insuficiência Cardíaca/fisiopatologia , Perna (Membro)/irrigação sanguínea , Torniquetes , Função Ventricular Esquerda , Adulto , Idoso , Idoso de 80 Anos ou mais , Ecocardiografia , Feminino , Insuficiência Cardíaca/diagnóstico por imagem , Hemodinâmica , Humanos , Perna (Membro)/diagnóstico por imagem , Masculino , Pessoa de Meia-Idade , Ventriculografia com Radionuclídeos , Volume SistólicoRESUMO
The efficacy and safety of oral verapamil, 240 mg, with or without digoxin were studied in 52 patients with chronic atrial fibrillation at rest, and during mild and maximal exercise. Twenty-four patients were studied during the following therapeutic modalities: no therapy; digoxin, 0.25 mg and 0.5 mg daily; digoxin, 0.25 mg and verapamil; and verapamil alone. Heart rate at rest and during all levels of exercise was decreased significantly (p less than 0.005), either by combining digoxin with verapamil or by verapamil therapy alone. In contrast, the excessive heart rate response to exercise was not prevented by digoxin even with good serum concentrations. The improved control of heart rate with verapamil was associated with a significantly improved exercise capacity. Verapamil is an important and safe modality of treatment, with or without digoxin, in the long-term control of heart rate in chronic atrial fibrillation. It is superior to digoxin in controlling the ventricular rate and in improving exercise capacity.
Assuntos
Fibrilação Atrial/tratamento farmacológico , Digoxina/uso terapêutico , Verapamil/uso terapêutico , Administração Oral , Adulto , Idoso , Fibrilação Atrial/fisiopatologia , Ensaios Clínicos como Assunto , Digoxina/administração & dosagem , Digoxina/metabolismo , Quimioterapia Combinada , Teste de Esforço , Feminino , Meia-Vida , Frequência Cardíaca/efeitos dos fármacos , Humanos , Masculino , Pessoa de Meia-Idade , Fatores de Tempo , Verapamil/administração & dosagem , Verapamil/metabolismoRESUMO
Acquired left ventricular-right atrial communication due to infective endocarditis was diagnosed in a 64-year-old patient by transesophageal echocardiography and confirmed by cardiac catheterization. The patient was initially treated medically and then referred for corrective surgery.
Assuntos
Ecocardiografia Transesofagiana , Endocardite Bacteriana/complicações , Fístula/diagnóstico por imagem , Cardiopatias/diagnóstico por imagem , Fístula/etiologia , Átrios do Coração , Cardiopatias/etiologia , Ventrículos do Coração , Humanos , Masculino , Pessoa de Meia-IdadeRESUMO
Stress echocardiography is used increasingly in the evaluation of coronary artery disease. The echocardiographic evaluation of ischemia is based on stress-induced changes in wall motion and wall thickening of the ischemic segments. Studies have demonstrated that left ventricular volumetric changes may induce changes in wall thickness. The aim of the study was to evaluate whether significant changes in ventricular volume, wall thickness, and wall thickening occur during stress echocardiography with atrial pacing. Seven German Landrace female pigs were studied 4 weeks after the induction of a small myocardial infarction. Echocardiographic measurements were conducted in noninfarcted segments on the short-axis view at baseline and during atrial pacing at 120, 150, and 180 beats/min. End-diastolic circumferential area decreased from 12.3 +/- 2.0 cm2 at baseline to 8.9 +/- 1.9 cm2 at 180 beats/min of atrial pacing (p < 0.01). Mean wall thickness (interventricular septal plus posterior wall thickness divided by 2) increased markedly and progressively from 6.7 +/- 0.6 mm at baseline to 9.8 +/- 1.0 mm at 180 beats/min (p < 0.01). The increase in wall thickness correlated inversely with end-diastolic area (r = -0.57; p < 0.01). Percent systolic thickening decreased from 38.9 +/- 12.0 at baseline to 14.9 +/- 7.4 at 180 beats/min of atrial pacing (p < 0.01). The decrease in percent wall thickening correlated with the increase in wall thickness (r = -0.71; p < 0.01). In conclusion, this study shows that a marked increase in wall thickness (pseudohypertrophy) and decrease in percent systolic thickening are observed during rapid atrial pacing in normal myocardium and do not indicate stress-induced left ventricular dysfunction.
Assuntos
Estimulação Cardíaca Artificial , Ecocardiografia , Coração/fisiopatologia , Isquemia Miocárdica/diagnóstico por imagem , Animais , Pressão Sanguínea/fisiologia , Diástole , Feminino , Septos Cardíacos/diagnóstico por imagem , Septos Cardíacos/patologia , Septos Cardíacos/fisiopatologia , Ventrículos do Coração/diagnóstico por imagem , Ventrículos do Coração/patologia , Ventrículos do Coração/fisiopatologia , Infarto do Miocárdio/diagnóstico por imagem , Infarto do Miocárdio/patologia , Infarto do Miocárdio/fisiopatologia , Isquemia Miocárdica/patologia , Isquemia Miocárdica/fisiopatologia , Suínos , Sístole , Função Ventricular Esquerda/fisiologiaRESUMO
BACKGROUND: Monitoring intravascular volume during surgery, especially in major cardiovascular procedures is necessary for appropriate fluid restoration and the maintenance of an adequate cardiac output. In estimating preload, both standard hemodynamic and echocardiographic parameters have been limited. The purpose of this study was to further define the effects of induced hypovolemia on the echocardiographic parameters. In particular, we sought to show whether a decrease in echocardiographic left ventricular area and volume was associated with a significant increase in left ventricular wall thickness (left ventricular pseudohypertrophy) and with changes in LV function. In addition, we sought to investigate the effects of rapid restoration of blood volume on cardiac dimensions and function. METHODS AND RESULTS: Seven anesthetized pigs underwent systemic and right heart pressures and cardiac output measurements. Two-dimensional echocardiographic parasternal long- and short-axis views were obtained during graded bleeding by rapid withdrawal of blood from an arterial cannula, with increments of 5% each up to 30% of calculated blood volume. After completion of the bleeding, the entire amount of the blood withdrawn was retransfused within 4 to 5 minutes. Both hemodynamic and echocardiographic measurements were performed at baseline, immediately after the completion of each stage of bleeding and after blood restoration. Mean (+/- standard deviation) left ventricular wall thickness (mean of septal and posterior wall thickness) was 6.3 +/- 0.1 mm at baseline, 8.3 +/- 1.5 mm at peak bleeding, and 6.2 +/- 0.1 after restoration (p < 0.01). Left ventricular mass did not change during the experiment. Left ventricular end-diastolic volume was 62.8 +/- 20.3 ml at baseline, 37.5 +/- 12.4 ml at peak bleeding (p < 0.0001), and 65.9 +/- 16.7 ml after blood restoration (p < 0.001 compared with 30% bleeding). H/r ratio (posterior wall thickness divided by left ventricular radius) increased from 0.29 +/- 0.07 at baseline to 0.50 +/- 0.19 at peak bleeding returning to 0.26 +/- 0.04 after restoration. Left ventricular ejection fraction was 0.53 +/- 0.10 at baseline and 0.55 +/- 0.20 at peak bleeding (not significant), decreasing to 0.38 +/- 0.11 after blood restoration (p < 0.05 compared with 30% bleeding). End-diastolic volume correlated closely with right atrial pressure (r = -0.82), capillary wedge pressure (r = -0.78), and stroke volume (r = 0.74). Left ventricular ejection fraction inversely correlated with left ventricular end-diastolic volume (r = -0.48) and with end-systolic wall stress (r = -0.62). The changes in interventricular septal and posterior wall thickness were inversely related to left ventricular end-diastolic volume (r = -0.72 and -0.35, respectively). CONCLUSIONS: This study shows that transient concentric left ventricular remodeling (pseudohypertrophy), a phenomenon previously described in cardiac tamponade and during rapid atrial pacing is commonly seen during hypovolemia. This new sign may further enhance the echocardiographic estimation of left ventricular preload.
Assuntos
Volume Sanguíneo , Ventrículos do Coração/diagnóstico por imagem , Hipertrofia Ventricular Esquerda/diagnóstico por imagem , Função Ventricular Esquerda , Animais , Feminino , Hemodinâmica , Suínos , UltrassonografiaRESUMO
Modest postural changes may trigger symptoms of cerebral ischemia, and these are usually attributed to "postural hypotension." The mere act of sitting up in bed induced paroxysmal atrioventricular block with symptoms sufficiently severe to warrant pacemaker implantation, without changes in blood pressure, in two patients. These cases illustrate an easily treatable mechanism for posturally induced cerebral ischemia that may completely escape clinical detection if not looked for.
Assuntos
Isquemia Encefálica/etiologia , Bloqueio Cardíaco/etiologia , Movimento , Idoso , Idoso de 80 Anos ou mais , Eletrocardiografia , Feminino , Humanos , Hipotensão Ortostática/complicações , Pessoa de Meia-Idade , SupinaçãoRESUMO
Timolol is a new beta blocker with cardioselective properties. A single blind controlled study was performed to assess the efficacy of timolol maleate in doses of 10 to 30 mg per day in 20 patients affected by stable angina pectoris. The patients received a placebo for a baseline period of 2 weeks, followed by 12 weeks of timolol. The number of anginal attacks dropped from 14.9 attacks per week in the baseline period to a minimum of 4.6 attacks per week in the sixth week of treatment (P less than 0.01). The number of tablets of nitroglycerin taken per week was reduced from 6.5 during the baseline period to 2.3 in the sixth week of treatment. Resting heart rate decreased from a baseline mean value of 72 beats per minute to 51.7 and 53.7 per minute at weeks 6 and 12 respectively (P less than 0.01). Blood pressure both at rest and during exercise was significantly reduced. The mean work index measured during bicycle ergometry was 127 units before treatment; it increased by 29.4 units and 36.1 units during week 6 and week 12 respectively (P less than 0.05). There was a marked symptomatic improvement in 50% of the patients. Mild fatigue was a common side effect but it disappeared following reduction of dose. We concluded that timolol maleate significantly reduces the number of anginal attacks and increases the work capacity of patients affected by stable angina pectoris