Bloqueio do ramo esquerdo durante cintilografia de perfusão do miocárdio com dipiridamol: evento raro associado à doença arterial coronária grave e desfecho fatal / Left bundle branch block during dipyridamole myocardial perfusion scintigraphy: rare event associated with severe coronary artery disease and fatal outcome

RELATO DE CASO: JS, masculino, 71 anos, hipertenso e dislipidêmico, apresentando dor precordial típica há um ano. Em uso de captopril, AAS, nitrato, carvedilol e sinvastatina. Realizada cintilografia de perfusão do miocárdio (CPM) com dipiridamol (DIPI). Eletrocardiograma (ECG) de repouso: ritmo sinusal, bloqueio atrioventricular de 1° grau e sobrecarga de ventrículo esquerdo. Após injeção do DIPI, paciente referiu dor precordial, com aparecimento de bloqueio do ramo esquerdo (BRE). Foi administrado aminofilina no 4° e o 8°min após DIPI, com melhora parcial da dor após nitrato sublingual. Por persistência da dor, foi submetido à cineangiocoronariografia, detectando-se lesões de 90% no 1/3 proximal da artéria descendente anterior (DA) e 70% no óstio do 2°diagonal (DG2). Foi realizado implante de stent (2 na DA e 1 em DG2), aspiração de trombo distal e administração intracoronária de vasodilatadores. Apesar da ausência de lesões residuais, paciente evoluiu com parada cardiorrespiratória, sem retorno à circulação espontânea após três horas de reanimação cardiorrespiratória. Introdução: A doença cardiovascular é a principal causa de morte no mundo. A associação da imagem da CPM, ao estresse físico e farmacológico, aumenta a sensibilidade no diagnóstico e estratificação de risco da doença arterial coronária. DISCUSSÃO: As provas farmacológicas representam alternativas em pacientes com limitação física, impedimento clínico ou em uso de betabloqueadores. São empregados como vasodilatadores o dipiridamol e a adenosina, que induzem aumento máximo do fluxo coronário. Estudos comprovam que o uso do DIPI é seguro, com baixa morbimortalidade. As manifestações associadas ao DIPI ocorrem em torno de 50% dos pacientes, como rubor, dor torácica, cefaléia, hipotensão, náusea e broncoespasmo. Alterações de ECG têm baixa incidência durante a prova. A ocorrência de distúrbio da condução pelo ramo esquerdo não é documentada como evento associado à CPM com DIPI. No presente estudo, a ocorrência do BRE esteve associada ao quadro de síndrome coronária aguda, com evolução fatal, mesmo após medidas metodológicas habituais dentro do laboratório de hemodinâmica. CONCLUSÃO: a presença de BRE durante prova farmacógica é rara, podendo associar-se à doença arterial coronária grave. (AU)

Exercise may cause myocardial ischemia at the anaerobic threshold in cardiac rehabilitation programs.

Myocardial ischemia may occur during an exercise session in cardiac rehabilitation programs. However, it has not been established whether it is elicited when exercise prescription is based on heart rate corresponding to the anaerobic threshold as measured by cardiopulmonary exercise testing. Our objective was to determine the incidence of myocardial ischemia in cardiac rehabilitation programs according to myocardial perfusion SPECT in exercise programs based on the anaerobic threshold. Thirty-nine patients (35 men and 4 women) diagnosed with coronary artery disease by coronary angiography and stress technetium-99m-sestamibi gated SPECT associated with a baseline cardiopulmonary exercise test were assessed. Ages ranged from 45 to 75 years. A second cardiopulmonary exercise test determined training intensity at the anaerobic threshold. Repeat gated-SPECT was obtained after a third cardiopulmonary exercise test at the prescribed workload and heart rate. Myocardial perfusion images were analyzed using a score system of 6.4 at rest, 13.9 at peak stress, and 10.7 during the prescribed exercise (P < 0.05). The presence of myocardial ischemia during exercise was defined as a difference > or = 2 between the summed stress score and summed rest score. Accordingly, 25 (64%) patients were classified as ischemic and 14 (36%) as nonischemic. MIBI-SPECT showed myocardial ischemia during exercise within the anaerobic threshold. The 64% prevalence of ischemia observed in the study should not be looked on as representative of the whole population of patients undergoing exercise programs. Changes in patient care and exercise programs were implemented as a result of our finding of ischemia during the prescribed exercise.

Exercise may cause myocardial ischemia at the anaerobic threshold in cardiac rehabilitation programs

Myocardial ischemia may occur during an exercise session in cardiac rehabilitation programs. However, it has not been established whether it is elicited when exercise prescription is based on heart rate corresponding to the anaerobic threshold as measured by cardiopulmonary exercise testing. Our objective was to determine the incidence of myocardial ischemia in cardiac rehabilitation programs according to myocardial perfusion SPECT in exercise programs based on the anaerobic threshold. Thirty-nine patients (35 men and 4 women) diagnosed with coronary artery disease by coronary angiography and stress technetium-99m-sestamibi gated SPECT associated with a baseline cardiopulmonary exercise test were assessed. Ages ranged from 45 to 75 years. A second cardiopulmonary exercise test determined training intensity at the anaerobic threshold. Repeat gated-SPECT was obtained after a third cardiopulmonary exercise test at the prescribed workload and heart rate. Myocardial perfusion images were analyzed using a score system of 6.4 at rest, 13.9 at peak stress, and 10.7 during the prescribed exercise (P < 0.05). The presence of myocardial ischemia during exercise was defined as a difference ≥2 between the summed stress score and summed rest score. Accordingly, 25 (64 percent) patients were classified as ischemic and 14 (36 percent) as nonischemic. MIBI-SPECT showed myocardial ischemia during exercise within the anaerobic threshold. The 64 percent prevalence of ischemia observed in the study should not be looked on as representative of the whole population of patients undergoing exercise programs. Changes in patient care and exercise programs were implemented as a result of our finding of ischemia during the prescribed exercise.

Selection of patients for myocardial perfusion scintigraphy based on fuzzy sets theory applied to clinical-epidemiological data and treadmill test results.

Coronary artery disease (CAD) is a worldwide leading cause of death. The standard method for evaluating critical partial occlusions is coronary arteriography, a catheterization technique which is invasive, time consuming, and costly. There are noninvasive approaches for the early detection of CAD. The basis for the noninvasive diagnosis of CAD has been laid in a sequential analysis of the risk factors, and the results of the treadmill test and myocardial perfusion scintigraphy (MPS). Many investigators have demonstrated that the diagnostic applications of MPS are appropriate for patients who have an intermediate likelihood of disease. Although this information is useful, it is only partially utilized in clinical practice due to the difficulty to properly classify the patients. Since the seminal work of Lotfi Zadeh, fuzzy logic has been applied in numerous areas. In the present study, we proposed and tested a model to select patients for MPS based on fuzzy sets theory. A group of 1053 patients was used to develop the model and another group of 1045 patients was used to test it. Receiver operating characteristic curves were used to compare the performance of the fuzzy model against expert physician opinions, and showed that the performance of the fuzzy model was equal or superior to that of the physicians. Therefore, we conclude that the fuzzy model could be a useful tool to assist the general practitioner in the selection of patients for MPS.

Selection of patients for myocardial perfusion scintigraphy based on fuzzy sets theory applied to clinical-epidemiological data and treadmill test results

Coronary artery disease (CAD) is a worldwide leading cause of death. The standard method for evaluating critical partial occlusions is coronary arteriography, a catheterization technique which is invasive, time consuming, and costly. There are noninvasive approaches for the early detection of CAD. The basis for the noninvasive diagnosis of CAD has been laid in a sequential analysis of the risk factors, and the results of the treadmill test and myocardial perfusion scintigraphy (MPS). Many investigators have demonstrated that the diagnostic applications of MPS are appropriate for patients who have an intermediate likelihood of disease. Although this information is useful, it is only partially utilized in clinical practice due to the difficulty to properly classify the patients. Since the seminal work of Lotfi Zadeh, fuzzy logic has been applied in numerous areas. In the present study, we proposed and tested a model to select patients for MPS based on fuzzy sets theory. A group of 1053 patients was used to develop the model and another group of 1045 patients was used to test it. Receiver operating characteristic curves were used to compare the performance of the fuzzy model against expert physician opinions, and showed that the performance of the fuzzy model was equal or superior to that of the physicians. Therefore, we conclude that the fuzzy model could be a useful tool to assist the general practitioner in the selection of patients for MPS.

Atuaçäo do exercício físico sobre os fatores de risco para doenças cardiovasculares / Acuation of physical exercise over risk factors for cardiovascular diseases

Etudos têm demonstrado que o sedentarismo está associado com maior incidência de doença coronária. Inversamente, a prática regular de atividade física é útil na prevençäo primária e secundária dessa importante doença. Os mecanismos pelos quais os exercícios físicos influem sobre a doença coronária näo estäo total totalmente elucidados. Sabe-se que a açäo benéfica da atividade física pode depender da melhora da capacidade cardiorrespiratória e da atuaçäo sobre vários fatores de risco importantes paro desencadeamento da aterosclerose coronária. Tem sido demonstrado que a intensidade de exercício capas de melhorar o perfil metabólico é menor do que a necessária para levar o incremento importante da capacidade cardiorrespiratória.

[Evaluation of the effects of macerated oral dipyridamole on the ergometric test]. / Avaliação dos efeitos do dipiridamol oral macerado no teste ergométrico.

Eighteen male patients with ages varying from 42 to 72 years (average 60.6), with coronary heart disease confirmed by angiography, on regular rehabilitation program and on regular use of dipyridamole were submitted to three exercise stress tests: a control test (TE1) and forty minutes after oral administration of macerated dipyridamole in doses of 150 mg (TE2) and 300 mg (TE3), respectively. The comparison between the data of TE2 and TE1 demonstrated that in TE2 the ST depression was more accentuated in the smallest maximal load attained and in the effort peak as well. The comparison between the data of TE3 and TE1 showed that in TE3: 1) the ST depression was more evident in the effort peak and in the smallest attained load; 2) the heart rate and the product heart rate x blood pressure were smaller in the effort peak; 3) the total time of angina and the time for its relief after effort, were longer. The other exercise stress test parameters did not show any significant changes. These data, suggest that the physical effort overload, after dipyridamole administration, produced a more marked myocardial ischemia, whose degree was proportional to the dose.