terça-feira, 31 de janeiro de 2012

As partes são o todo - by Fábio Soares


(se não quiser ver o vídeo inteiro - o qual vale bastante a pena - vá direto ao 5o minuto)

Em 1980, Francisco Torrent-Guasp demonstrou pela primeira vez, dissecando um coração bovino, que o músculo cardíaco é formado por um feixe muscular único, enrolado em si mesmo e ancorado nas suas extremidades nos anéis pulmonar e aórtico, sofrendo reflexão ao nível do septo interaventricular.



Portanto, é vedado ao médico pensar em ventrículos direito e esquerdo como músculos separados, como câmaras independentes, bem como imaginar que funções diastólica e sistólica são propriedades distintas. Na verdade, estamos lidando com um único feixe de músculo, distribuído em bandas  que apresentam despolarizações sucessivas e harmônicas. Qualquer comprometimento na estrutura muscular determina algum grau de disfunção, quer sistólica ou diastólica... A limitação de um método diagnóstico, não significa ausência de "doença". O desenvolvimento de novas técnicas vem refinando o diagnóstico e acompanhamento de várias patologias (Cardiomiopatia Chagásica na sua forma indeterminada, Amiloidose, Cardiomiopatia Hipertrófica, Verificação de viabilidade miocárdica, etc)
Right Ventricular Myocardial Systolic and Diastolic Dysfunction in Heart Failure with Normal Left Ventricular Ejection Fraction

Daniel A. Morris, MD, Mudather Gailani, MD, Amalia Vaz Perez, MD, Florian Blaschke, MD, Rainer Dietz, MD, Wilhelm Haverkamp, MD, and Cemil Ozcelik, MD, Berlin, Germany


Objective:


We hypothesized that in patients with heart failure with normal left ventricular (LV) ejection fraction (HFNEF), the same fibrotic processes that affect the subendocardial layer of the LV could also alter the subendocardial fibers of the right ventricle (RV). Consequently, these alterations and to a lesser extent chronically elevated pulmonary arterial pressures would lead to both systolic and diastolic subendocardial dysfunction of the RV (i.e., impaired RV longitudinal systolic and diastolic function) in patients with HFNEF.\


Methods:

Patients with HFNEF and a control group consisting of asymptomatic patients with LV diastolic dysfunction (asymptomatic LVDD) matched by age, gender, and LV ejection fraction were studied by twodimensional speckle-tracking echocardiography.

Results:
A total of 565 patients were included (201 with HFNEF and 364 with asymptomatic LVDD). RV longitudinal diastolic (RV global longitudinal early-diastolic strain rate [RV-SRe]) and systolic (RV global longitudinal systolic strain [RV-Strain]) function were significantly more impaired in patients with HFNEF than in patients with asymptomatic LVDD (HFNEF: RV-Strain   14.41%  +/- 3.80% and RV-SRe 0.86 +/- 0.33 s 1; asymptomatic LVDD: RV-Strain 16.90% +/- 4.28% and RV-SRe 1.02 +/- 0.34 s 1; all P < .0001). On multiple regression analysis, LV global longitudinal systolic strain was the most important independent predictor of RV longitudinal systolic and diastolic function, in contrast with pulmonary arterial systolic pressure, which was weakly related to these functions. Furthermore, in patients with HFNEF the subendocardial function of both the LV and RV were significantly impaired in similar proportions. In that regard, in patients with HFNEF the prevalences of RV longitudinal systolic and diastolic dysfunction were 75% and 48%, whereas the rates of LV longitudinal systolic and diastolic dysfunction were 80% and 60%, respectively. In addition, patients with both systolic and diastolic longitudinal dysfunction of the RV presented worse New York Heart Association functional class.


 

Conclusion:
In patients with HFNEF, RV subendocardial systolic and diastolic dysfunction are common and possibly associated with the same fibrotic processes that affect the subendocardial layer of the LV and to a lesser extent with RV pressure overload. Furthermore, our findings suggest that RV longitudinal systolic and diastolic dysfunction could contribute to the symptomatology of patients with HFNEF. (J Am Soc Echocardiogr 2011;24:886-97.)

Nenhum comentário:

Postar um comentário