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Is the new professionalism and ACP's new ethics really just about following guidelines?

The Charter ( Medical Professionalism in the New Millennium.A Physician's Charter) did not deal with just the important relationship of ...

Thursday, November 12, 2020

Left Bundle Branch mediated cardiomyopathy- impressive results from His Bundle Pacing

 At least as early as 1989 CL Grines described significant functional abnormalities in patients with left bundle branch block (LBBB).

Blanc et al in 2005 and again Vaillant et al  in 2013  described patients with LBBB induced heart failure (HR) that was impressively improved  by cardiac resynchronization therapy (CRT) in the form of bi ventricular pacing.Blanc commented that this was a new concept of left ventricular dyssynchrony - induced cardiomyopathy.

In spite of the fact that it has been known for 30 years  that  left ventricular functional changes are caused by LBBB and it has been fifteen years since a LBBB induced cardiomyopathy was described we continue to find current journal articles that depict BBB without other cardiac disease as not a clinical problem.

R Singh et al (1) recently reported the results of His Bundle Pacing on 9 patients with LBBB-mediated cardiomyopathy. The left ventricular ejection fraction increased on average from 25% to 50% while the left ventricular end-diastolic volume decreased from 55 to 48mm., while the QRS duration decreased from 152 to 115 milliseconds. This represents another article indicating that His pacing gives results as  good or perhaps better than Bi ventricular pacing for CRT. 

1) Singh, R et al His-Bundle pacing: A novel treatment for left bundle branch-mediated cardiomyopathy.

J of Cardiovascular electrophysiology 2020 vol 31 no 10.

Wednesday, November 04, 2020

Habitual aerobic exercise and arterial stiffness

It has been known for at least 20 years or more than endurance exercise done over a  period of  time can mitigate the age related increase in central artery stiffness.Work published by Tanaka in 2000 and  data from the BLSA in 2003 established that relationship. refs 2 and 3 The duration and intensity of exercise are important determinates of that mitigation .

Sedentary aging is associated with changes in the left ventricle (LV) , including :
increase in wall thickness,increased mass and decreased diastolic function.The LV is stiffer and relaxes less well It has been suggested that the heart burdened by these accountments of aging are sitting ducks for a second hit  (High blood pressure,obesity,diabetes) which could lead to heart failure with preserved ejection fraction (HFpEF), a type of heart failure constituting about  one half of all HF cases and for which there is no good treatment.

Gates and colleges (1)from University of Colorado studied the question of whether  attenuation of age related increased in arterial stiffness by long term endurance exercise might help preserve LV structure and diastolic function. This was a reasonable hypothesis as it had ben the general party line  for years that the increased afterload imposed on the left ventricle from stiffening of the aorta with loss of its capacitance function would produce deleterious changes in the left ventricle and secondarily left atrium .

 In a cross sectional study  of 138 young,middle aged and older men who were sedentary, recreationally active or endurance trained ,Gates  found that regular endurance exercise did not"consistently modulate the changes in LV structure and function that occur with physiological aging in men" . Several publications from Ben Levine and the group from the Institute for Exercise and  Environmental Medicine in Dallas  have provided data that I believe provides refutation of that conclusion,their data demonstrating favorable remodeling of the Left Ventricle with maintenance of a more youthful left ventricular  compliance.

1)Gates,P E Left ventricular structure and diastolic function with human ageing. European Journal of Cardiology. 2003,24,2213-2220

2)Tanaka,H Aging habitual exercise and dynamic arterial compliance. Circ. 200 102, 1270

3)Havlik,R Association of physical activity and less vascular stiffness in 70-79 year old.The health ABC Study. J of Aging and Physical Activity. 2003, vol 11 , issue 2 156-166