Cardiac surgery for Chagas disease.

Although Chagas disease is a rare entity in North America, it is associated with significant cardiac morbidity. It is estimated that 20-30% of those who are infected will eventually develop cardiovascular disease secondary to Chagas disease. We review the literature and share our experience on the surgical management of this challenging patient population.

What is the clinical significance of ventricular mural antagonism?

Recent morphological studies provide evidence that the ventricular walls are arranged as a 3D meshwork of aggregated cardiomyocyte chains, exhibiting marked local structural variations. In contrary to previous findings, up to two-fifths of the chains are found to have a partially transmural alignment, thus deviating from the prevailing tangential orientation. Upon contraction, they produce, in addition to a tangential force, a radial force component that counteracts ventricular constriction and aids widening of the ventricular cavity. In experimental studies, we have provided evidence for the existence of such forces, which are auxotonic in nature. This is in contrast to the tangentially aligned myocytes that produce constrictive forces, which are unloading in nature. The ventricular myocardium is, therefore, able to function in an antagonistic fashion, with the prevailing constrictive forces acting simultaneously with a dilatory force component. The ratio of constrictive to dilating force varies locally according to the specific mural architecture. Such antagonism acts according to local demands to preserve the ventricular shape, store the elastic energy that drives the fast late systolic dilation and apportion mural motion to facilitate the spiralling nature of intracavitary flow. Intracavitary pressure and flow dynamics are thus governed concurrently by ventricular constrictive and dilative force components. Antagonistic activity, however, increases deleteriously in states of cardiac disease, such as hypertrophy and fibrosis. ß-blockade at low dosage acts selectively to temper the auxotonic forces.

Beta-blockade at low doses restoring the physiological balance in myocytic antagonism.

OBJECTIVE: The ventricular mass is organized in the form of meshwork, with populations of myocytes aggregated in a supporting matrix of fibrous tissue, with some myocytes aligned obliquely across the wall so as to work in an antagonistic fashion compared to the majority of myocytes, which are aggregated together in tangential alignment. Prompted by results from animal experiments, which showed a disparate response of the two populations of aggregated myocytes to negative inotropic medication, we sought to establish whether those myocytes that aggregated so as to extend obliquely across the thickness of the ventricular walls are more sensitive to beta-blockade than the prevailing population in which the myocytes are aggregated together with tangential alignment. If the two populations respond in similar differing fashion in the clinical situation, we hypothesize that this might help to explain why drugs blocking the beta-receptors improve function of the ventricular pump in the setting of congestive cardiac failure. METHODS: We implanted needle probes in 13 patients studied during open heart surgery, measuring the forces generated in the ventricular wall and seeking to couple the probes either to myocytes aggregated together with tangential alignment or to those aggregated in oblique fashion across the ventricular walls. In a first series of patients, we injected probatory doses intravenously, amounting to a total bolus of 40-100mg Esmolol, while in a second series, we gave fixed yet rising doses of 5, 10, and 20mg Esmolol in three separate boluses. RESULTS: Forces recorded in the aggregated myocytes with tangential alignment decreased insignificantly upon administration of low doses (57.1+/-12.4 mN-->56.6+/-7.6 mN), while forces recorded in the myocytes aggregated obliquely across the ventricular wall showed a significant decrease in the mean (59.3+/-11.6 mN-->47.4+/-6.4 mN). CONCLUSIONS: The markedly disparate action of drugs blocking beta-receptors at low dosage seems to be related to the heterogeneous extent, and time course, of systolic loading of the myocytes. This, in turn, depends on whether the myocytes themselves are aggregated together with tangential or oblique alignments relative to the thickness of the ventricular walls.

The relationship between structure and function: why does reshaping the left ventricle surgically not always result in functional improvement?

Surgical strategies recently introduced to improve ventricular function have been based on the concepts of reduction of ventricular diameter, synchronization of myocardial activity, passive support of diastolic ventricular shape, and active support of systolic ventricular constriction. They have depended on several established theoretical assumptions, not all of which are totally valid. Clinical results have proved markedly variable. This is especially true for procedures designed to reduce the radius of the left ventricle. Some have reported up to 80% mortality, whereas others achieve results comparable with those for heart transplantation. Because of this, the method runs the risk to be rejected, or else, its more widespread application will be postponed until essential details concerning the basic concepts have been elucidated. It is these details which we discuss in this review.

Partial left ventriculectomy in elderly patients not suitable for heart transplantation.

BACKGROUND: Although donor scarcity and intolerance to immunosuppression tend to exclude elderly patients from transplantation, partial left ventriculectomy (PLV) has been performed without bias against advanced age. METHODS: Among 392 patients undergoing PLV, 61 elderly patients aged 65 or older (> or =65) were compared with the rest of the patients in terms of underlying disease, postoperative course, and survival time. RESULTS: The aged patients (> or =65) compared to younger patients (<65), had ischemic disease (37.7% vs. 19.3%, p < 0.05) more frequently than cardiomyopathy (34.4% vs. 43.2%) or valvular disease (23.9% vs. 16.4%) and underwent lateral PLV (74% vs. 79%) more frequently than extended PLV (26% vs. 21%). Although the elderly patients required coronary bypass grafting more frequently (39.3% vs.17.2%, p < 0.05), surgical complexity was similar in terms of bypass time (63 minutes vs. 63 minutes) and percentage requiring cardiac arrest (31% vs. 44%). Despite advanced age, they required comparable ICU care (6.6 days vs. 5.4 days) and postoperative hospital stay (12 days vs. 11 days), resulting in a low but similar hospital survival (57% vs. 62%) and functional capacity after discharge (NYHA class 1.5 vs. 1.4). CONCLUSION: The results suggest that PLV can be performed in elderly patients (> or =65 years) with comparable risks and benefits with the younger patients, promoting its application in patients disqualified for heart transplantation because of age criteria.

Angiographic and hemodynamic follow-up of patients after partial left ventriculectomy.

Angiographic, Doppler-echocardiographic and hemodynamic studies early (+6 days) and late (+180 days) after partial left ventriculectomy (PLV) on 24 patients revealed that PLV decreased end-systolic volume (or dimension) more than the end-diastolic volume (or dimension), improving stroke volumes (or contractile excursion), and doubling ejection fraction (or fractional shortening). Results of PLV appeared to depend on a balance between improved systolic contractility and reduced diastolic performance. All these survivors had improved diastolic relaxation, suggesting myocardial viability is a prerequisite for PLV to be successful.

Left ventricular volume reduction surgery: The 4th International Registry Report 2004.

BACKGROUND AND METHODS: An international registry of left ventricular volume reduction (LVVR) procedures, including partial left ventriculectomy, has been expanded, updated, and refined to include 568 cases voluntarily reported from 52 hospitals in 12 countries. RESULTS: Gender, age, ventricular dimension, ethnology, myocardial mass, presence or absence of mitral regurgitation, as well as transplant indication, had little effect on event-free survival, which was defined as either absence of death or ventricular failure requiring mechanical assist or transplantation. Poor preoperative patient condition such as New York Heart Association classification IV, depressed contractility and decompensation requiring an emergency procedure were associated with reduced event-free survival. Other risk factors included an early surgery date, lack of experience, dilated cardiomyopathy as the underlying pathology and extended myocardial resection. Performance of LVVR reached a peak by 1998, but was largely abandoned by 2001, except in Asia, where experienced institutes continue to perform it in patients in better condition with preserved myocardial contractility. CONCLUSION: Avoidance of risk factors appears to have contributed to the recent survival improvement and may help stratify patients for LVVR. While performance has been decreasing, the concept has been extended to other LVVR and less invasive procedures, which are now under clinical trials.

Does repair of mitral regurgitation eliminate the need for left ventricular volume reduction?

BACKGROUND: Effects of partial left ventriculectomy (PLV) remain ill-defined because mitral regurgitation (MR) repair by isolated annuloplasty alone has been reported to improve patients with dilated left ventricle and severe MR. METHODS: Among patients undergoing PLV, 120 had paired pre- and postoperative (<1 week) Doppler echocardiograms. Effects of preoperative MR were studied by comparing 45 patients with no preoperative MR (MR-) and 75 patients with significant MR (MR+; MR = 1.51 when MR is enumerated as none = 0, mild = 1, moderate = 2). RESULTS: MR- patients as compared with the MR+ group were older (53.8 vs. 49.2 years, P = 0.047), had less frequent dilated cardiomyopathy (33.3% vs 49.3%,P <0.01), similar ventricular dimension (72.3 mm vs 73.0 mm), septal thickness (9.5 mm vs 9.6 mm), posterior wall, fractional shortening (15.9% vs 16.8%) and ventricular mass (330 g vs 345 g), resulting in comparably reduced functional capacity (NYHA 3.40 vs 3.67). Although the MR- group required significantly less frequent mitral procedure (64.4% vs 84.0%, P < 0.01) and shorter cardiac arrest time, they had similar postoperative MR (0.22 vs 0.39), highly significant parallel reduction in ventricular dimension (P < 0.001 in either group), and improved %FS (P <0.001 in either group), resulting in similar hospital survival (87.1% vs 86.4%) and 90-day survival (71.1% vs 78.7%) with significantly comparable improvement in functional class (P = 0.011 in both groups). Histological severity of interstitial fibrosis (P = 0.80), weight (P = 0.93), and thickness (P = 0.76) of excised myocardium was comparable between the two groups. CONCLUSION: Patients with no preoperative MR were found to benefit from PLV as did patients with significant MR. Beneficial effects of PLV appeared to derive mainly from volume reduction rather than abolished MR in this study.

Factors affecting ventricular function and survival after partial left ventriculectomy.

BACKGROUND: Partial left ventriculectomy (PLV) helps some patients but is deleterious in others. Selection of patients who will benefit from PLV, and exclusion of those who will not is necessary for safe and effective application of the procedure. METHODS: Sixty-nine consecutive patients who underwent PLV were monitored with pressure-volume relationship analyses, Doppler echocardiography, and histopathologic studies of excised myocardium. These parameters were correlated with postoperative stroke volume (SV, ml), cardiac output (CO, L/min), ventricular function (improved, no change, or deteriorated), and postoperative course (duration of survival and/or hospital discharge). RESULTS: Positive responders (n = 36) with increased SV at reduced end diastolic pressure had significantly larger preoperative end-systolic dimension, smaller SV, and less stroke work with milder fibrosis than non- or negative responders (n = 33). In multivariate analyses, poor preoperative hemodynamics were associated with increased SV and CO, but these improvements did not lead to improved survival. Postoperative survival was negatively affected by larger preoperative left ventricular end-diastolic volume and larger excised-muscle-weight. Milder fibrosis and thicker excised wall were consistently related to improved ventricular function and survival. CONCLUSION: Although effects of PLV are related to preoperative status, factors affecting postoperative ventricular function and survival were often discordant. While poor preoperative ventricular function was associated with functional improvement without survival benefit, milder fibrosis, thicker excised wall and less myocardial resection were positive contributors to improved ventricular function, discharge, and survival. Preoperative evaluation with more cases and variables are needed to identify patients more likely to benefit from PLV.

Partial left ventriculectomy--The Third International Registry Report 2002.

BACKGROUND: An international registry of partial left ventriculectomy (PLV) has been expanded, updated, and refined to include 440 cases voluntarily reported from 51 hospitals in 11 countries. RESULTS: Gender, age, ventricular dimension, etiology, ethnology, myocardial mass, operative variation or presence or absence of mitral regurgitation as well as transplant indication had no effects on event-free survival, which was defined as either absence of death or ventricular failure requiring ventricular assist device or listing for transplantation. Preoperative patient condition such as NYHA functional class IV, depressed contractility, and decompensation requiring an emergency procedure were associated with reduced event-free survival. Other risk factors included early date of surgery, lack of experience, and extended myocardial resection. Performance of PLV reached a peak by 1998 and was largely abandoned by 2000 except in Asia, where experienced institutes continue to perform PLV in patients in better condition with preserved myocardial contractility. CONCLUSION: Avoidance of delineated risk factors appears to improve recent survival and may help stratify high- or low-risk patients for PLV. An integrated approach with mechanical and biological circulatory assist may improve prognosis for patients with dilated failing hearts. While frequency of PLV has decreased, the concept of ventricular volume reduction has been extended to other volume reduction procedures and less invasive procedures now under clinical trial.

Timectomia e imunossupressäo em miastenia gravis: estudo prospectivo / Thymectomy and immunosupression in myasthenia gravis: a prospective study

Entre 1982 e 1988 24 mulheres e 6 homens com miastenia gravis foram submetidos a protocolo diagnóstico e terapêutico prospectivo e estandardizado. A idade variou de 10 a 74 anos (34 mais ou menos 16, média mais ou menos desvio padräo). Três com forma ocular foram tratados com piridostigmina. Quatro com forma generalizada, de idade avançada, receberam corticosteróide e/ou azatioprina. Vinte e três com a forma generalizada foram submetidos a timectomia seguida de prednisona e/ou azatioprina. Um paciente faleceu após a admissäo, em crise miastênica/colinérica. Dois outros tiveram complicaçöes menores da timectomia. De 19 pacientes seguidos por 1-60 (média 24) meses, 11 (58%) têm frqueza residual mas levam vida normal e 8 (42%) estäo em remissäo completa, um sem medicaçäo

Successful reversal of pulmonary hypertension in Eisenmenger complex / Reversão com Sucesso da Hipertensão Pulmonar no Complexo de Eisenmenge

We present a case of a 19-year old female with systemic pulmonary artery (PA) pressure due to a congenital ventricular septal defect (VSD) and atrial septal defect (ASD). She was pink at rest and cyanotic on exercise. Lung biopsy revealed grade IV pulmonary vascular changes. As a preliminary step PA was banded to increase right-to-left shunt and decrease aortic (Ao) saturation with consequent decrease in PA saturation. After one year, when she was no longer cyanotic, even on exercise, lung biopsy revealed total regression of pulmonary vascular changes. As a definitive procedure VSD and ASD were closed and PA was debanded. Cardiac catheterization one week postoperatively showed PA pressure to be 50of systemic pressure. We postulate that reversal of pulmonary vascular changes were due to lowered PA saturation. We further believe that lower PA pressure could have contributed to this regression of pulmonary vascular changes. We performed the same procedure in six more patients with similar positive clinical response. This new concept brings renewed hope to many children who otherwise are candidates for heart lung transplantation.

Autotransplante cardíaco: um novo método no tratamento de problemas cardíacos complexos / Heart autotransplantation: a new method for treatment of complex cardiac problems

No período de janeiro de 1990 a maio de 1995 foram operados com a técnica do auto transplante cardíaco 92 pacientes com cardiopatias complexas e arritmias supraventriculares, principalmente fibrilaçao atrial (n=89), reentrada(n=2),QT longo(n=l). O sexo feminino predominou (n=63). A idade variou de l8 a 76 anos (m=43). Os defeitos concomitantes foram: átrio esquerdo gigante (medido pelo ecocardiograma > 6 cm) (n=65); átrio direito gigante (n=9); átrio esquerdo aumentado (< 6 cm/>4 cm) (n=23); estenose mitral (n=46); insuficiência mitral (n=28); dupla lesao mitral (n=l6); estenose aórtica (n=l2); insuficiência aórtica (n=5); insuficiência tricúspide (n=78); trombose atrial (n=23); calcificaçao atrial (n=l2); hipertensao pulmonar (n=86); flbroelastose biventricular (n=3); rotura atrioventricular (pós-troca de valva mitral) (n=l); aneurisma da raiz aórtica (n=l); ventriculectomia parcial (n=8); 88 pacientes saíram do centro cirúrgico em ritmo sinusal e assim permaneceram; 6 precisaram de drogas inotrópicas e 3 de drogas antiarrítmicas. Todos os pacientes que apresentavam átrio esquerdo ou direito gigante com fibrilaçao atrial tiveram seus átrios reduzidos ao tamanho normal. Nao houve mortalidade operatória e 6 evoluíram a óbito hospitalar. Na reavaliaçao aos seis meses de pós-operatório, os sobreviventes estavam bem, em ritmo sinusal. A técnica do autotransplante cardíaco facilita o reparo intracardíaco, proporciona a reduçao atrial e conseqüente retorno do paciente ao ritmo sinusal e abre novas perspectivas.

Ventriculectomia parcial: um novo conceito no tratamento cirúrgico de cardiopatias em fase final / Partial ventriculectomy: a new concept in the surgical treatment of end stage cardiopathies

A melhora clínica da funçao cardíaca pós aneurismectomia de ventrículo esquerdo e/ou cardiomioplastia com o músculo grande dorsal parece ser, ao menos parcialmente, devida ao remodelamento do ventrículo esquerdo. Através de pesquisa em nosso laboratório experimental com carneiros, demonstramos que o aumento do diâmetro do ventrículo é mais importante que a perda de massa muscular para a deterioraçao da funçao ventricular. Sabendo-se que em miocardiopatia dilatada nao ocorre aumento de massa muscular, reduzimos o diâmetro do ventrículo para o normal, em uma série consecutiva de pacientes com esta lesao. No período de 1984 a 1995, foram operados com esta nova técnica, denominada, entao, "Ventriculectomia Parcial", lO3 pacientes portadores de miocardiopatias complexas e insuficiência cardíaca congestiva (NYHA IV). A operaçao é baseada na lei de Laplace (T=P.1l.D) e consistiu na remoçao de uma fatia de músculo da parede lateral do ventrículo esquerdo, iniciando-se na ponta deste, estendendo-se entre os músculos papilares e terminando próximo ao anel mitral. A cirurgia é realizada sob circulaçao extracorpórea normotérmica e nao se utiliza cardioplegia. Todos os pacientes foram avaliados pré-operatoriamente com ecodopplercardiografia e ventriculografia digital, os quais revelaram fraçao de ejeçao < 20 por cento, confirmando estes pacientes como candidatos ao transplante cardíaco. A maioria era do sexo masculino (n=73) e a idade variou de l9 a 74 anos. As doenças foram: miocardite a virus (n=l2); pós miocardioplastia (n=l); doença de Chagas (n=l5); doença valvar (n=38); doença isquêmica (n=l6); idiopática (n=21). Obitos hospitalares (ocorridos nos primeiros 30 dias da cirurgia) (n=l3): embolia pulmonar (n=4); insuficiência renal (n=5); sangramento (n=4). Obitos tardios (ocorridos depois do 30( dia de cirurgia) (n=lO): arritmia (n=6); "insuficiência cardíaca" (n=2); causa desconhecida (n=2); 8 pacientes precisaram ser reoperados por sangramento. Nao houve infecçao e nenhum paciente precisou balao intra-aórtico. Todos saíram com nitroprussiato e 19 pacientes, com inotrópicos. A ventriculografia e a ecocardiografia pós-op mostraram melhora acentuada da FE (de 100 por cento a 300 por cento). Em conclusao, a nova técnica "Ventriculectomia Parcial", com o objetivo de reduzir o diâmetro do ventrículo esquerdo, pode beneficiar pacientes em estágio final de cardiopatia dilatada. Este novo conceito pode, na nossa experiência, proporcionar ao paciente melhora clínica significativa e prolongamento de sua vida.

Resultados precoces de la ventriculectomía parcial izquierda (operación de batista) / Early results with partial left ventriculectomy (the Batista operation)

Introducción y objetivos. La escasez de donantes así como la morbimortalidad asociada al trasplante han motivado el planteamiento de otras opciones quirúrgicas para la miocardiopatía dilatada en fase terminal. Entre ellas se encuentra la ventriculectomía parcial izquierda, que implica la reducción del diámetro y la masa ventricular. Presentamos en este trabajo la experiencia inicial (no limitada a la alternativa al trasplante) y los resultados inmediatos de esta técnica en nuestro centro. Métodos. Hemos intervenido a 6 pacientes con miocardiopatía dilatada: cuatro de etiología idiopática y con motivos de exclusión para trasplante cardíaco y dos de origen valvular. Se practicó resección de la pared lateral de ventrículo izquierdo entre los músculos papilares y cierre directo con sutura continua, asociándose anuloplastia mitral en 5 casos, tricuspídea en uno y sustitución valvular aórtica en los dos últimos. Resultados. Dos pacientes precisaron balón de contrapulsación; uno falleció por shock cardiogénico refractario y el otro a los 15 días tras episodios de arritmia ventricular. Los estudios ecocardiográficos intraoperatorios pusieron de manifiesto una reducción significativa del diámetro diastólico (de 8,7 a 6,8 cm; p = 0,02) y de la insuficiencia mitral, con una mejoría en la fracción de eyección (del 17 al 27 por ciento; p = 0,09) mantenidos en el ecocardiograma previo al alta. Conclusiones. La técnica es reproducible y adecuada como posibilidad terapéutica en la insuficiencia cardíaca en fase terminal. Quedan por precisar el grupo y tipo de paciente ideal, el manejo perioperatorio y el soporte a largo plazo (AU)