Cardiac autonomic impairment and early myocardial damage involving the right ventricle are independent phenomena in Chagas' disease

Impaired autonomic control of heart interval changes to Valsalva manoeuvre in Chagas' disease without overt manifestation

“…One possible limitation of our study concerns the lack of extensive validation of the new Valsalva manoeuvre-associated indices of heart interval changes used, although their good reliability (Junqueira, 1990;Marin-Neto et al, 1998), the strong confidence that the present findings in Chagas' disease subjects examined are really true considering the pertinence of the results, and the employment of some such indices by others proving its validity . Moreover, ongoing analysis in our laboratory has shown significant and good correlation between the indices presently used and the baroreflex sensitivity measured by the phenylephrine injection method (unpublished data).…”

“…Initially, each individual was instructed in the Valsalva manoeuvre and practiced it sometimes for training. In sequence, after sufficient time of resting, three to four spaced valid manoeuvres were done for each subject in the rest supine position by blowing with the closed glottis into the mouthpiece-tubing connected to an aneroid manometer in order to maintain a constant expiratory intra-oral pressure of 40 mm Hg for 20 s according to standardized previous protocol (Manc ßo et al, 1969;Eckberg, 1980;Junqueira, 1990;Marin-Neto et al, 1998). The Valsalva manoeuvre comprises four phases of baroreflex heart interval changes to arterial pressure modifications: (1) rapid inspiration and onset of the expiratory straining with a variably present evanescent bradycardia associated to a transient systolic arterial pressure rise (phase I); (2) maintenance of the straining with an incremental relative tachycardia secondary to a progressive arterial pressure decrease (phase II); (3) release of straining with progression of the tachycardia to the maximum following an additional sudden dip in arterial pressure (phase III); (4) post-straining cessation of the tachycardia in variable time and onset of the progressive relative bradycardia in response to the rapid arterial pressure overshooting, which lasts several seconds until the complete recovery to the basal level (phase IV).…”

Chagas' heart disease

“…Regional wall motion abnormalities and global right ventricular dysfunction may be detected in patients with the indeterminate or isolated digestive form of the disease in whom LV performance is still preserved 68,69 .…”

“…Dilation is usually more conspicuous Chagas' heart disease Arq Bras Cardiol volume 72, (nº 3), 1999 in the right chambers 84 , and signs of systemic congestion (ascites, hepatomegaly) predominate over lung congestion 51 . It is possible that this peculiar feature of Chagas' heart disease could be explained by early severe damage of the right ventricle, a chamber frequently neglected in many investigations that included cardiac functional evaluation 68,69 .…”

Comprometimento parassimpático no estágio pré-clínico da doença de chagas crônica

“…Therefore, the relationship between the autonomic and contractile dysfunctions cannot be established in terms of cause and effect in one or other direction 10 . This concept is reinforced by other studies demonstrating that the cardiac autonomic dysfunction is a precocious and independent phenomenon of the contractile alteration 2,7,14,15 , including the recent work by Gerbi et al, which also detected no relationship between both disturbances using also heart rate variability analysis to characterize the autonomic status 1 .…”