Caution: This is a fairly lengthy article . Optimal Reading time 15 minutes
Cardiac failure is a progressive systemic disease , even though the primary problem originates in the heart .Most of the symptoms and clinical features are related to Neuro-Endocrine activation instigated by poor pumping function.When the diminishing cardiac function exceeds the compensatory mechanisms , full blown cardiac failure sets in and get into a vicious downward spiral unless intervened.
The conventional treatment model involves on three targets.
- Reduction in pre -load(Diuretics)
- Improving contractility (Inotropics)
- Reduction in afterload (Vaso- dilators)
Though the concept looked attractive there are many missing links . Medical treatment lags far behind the desired goals. Still , it can stabilize most of the patients with cardiac failure till they reach very late stages.
Nomenclature
Inadequately treated CHF is not synonymous with refractory failure . But , practically it is the commonest cause for refractionaries . Hence , every patient must be scrutinised meticulously for adequacy of treatment.
Primary mitral , aortic valve lesions causing cardiac failure need not be considered as refractory cardiac failure . In the strict sense myocardial disease /damage either idiopathic or secondary to CAD would form bulk of refractory failure .
(For example a patient with critical aortic stenosis with severe LV dysfunction is technically refractory cardiac failure but functionally it could be a simple expression of after load mis- match )
COPD -Cor pulmonale /Primary pulmonary hypertension / End stage congenital heart disease and Eisenmenger syndromes form separate group of CHF and would not be discussed here.
The valves , the fibrous skeleton, the pericardium are integral parts of the heart . Individual disease process can affect these compartments in a differential pattern .
When we refer to refractory heart failure it amounts only two large disease groups.Ischemic and idiopathic cardiomyopathy.The whole myocardium is a single unit. If it is destined to fail it will fail in toto. There can be reversible factors that can be addressed.
The coronary artery though not a part of heart has a major say in the outcome of cardiac failure as they determine the cardiac muscle integrity.In every patient with refractory cardiac failure , an attempt must be made to rule out any re-vascularisible lesions.
The primary difference between ischemic and Idiopathic DCM is , in ischemic DCM left ventricular segments are predominantly involved . RV function is relatively preserved until very late stages.
Patient factors
Age , gender, body weight , systemic illness that increase metabolic demands have an adverse impact . Diabetic patients fare poorly .
Fluid management and diuretics
In refractory cardiac failure the renal blood flow is reduced .Diuretics usage will further worsen this if ECF is depleted .
So it is obvious we have to use it very judiciously .
Why only certain patients with cardiac failure develop significant edema while others do not ?
This lies in the response of neuro -humoral activation of secondary RASS system.
Both inadequate and excess diuretic can perpetuate the status.
Intra vascular hypovolemia and effective renal blood flow reduced
Diuretic strategies
- Increasing the dose
- Adding another ( Switching over to another loop diuretic like Bumetanide, or Toresemide can be tried )
- Sequential nephron blockade ( Add metalazone a powerful thiazide acting in proximal tubule to be used with caution risk of hypokalemia)
- Continuous IV infusion is an option
Ultra filtration can be used in severely volume over loaded patients.
Refractory diastolic failure . How common is that ?
The incidence of significant LV filling defect are more commonly observed.There is no specific drugs available to tackle this .It may be argued digoxin and other positive inotropes worsen diastolic dysfunction.This may not be true in the bed side.Unless severe LV restriction feature are present digoxin can be continued.
The simple and effective way to improve LV filling in the presence of diastolic filling defect , is to slow down the heart rate. At low heart rates diastolic filling period prolongs and dysfunction tend to vanish.Beta blockers usefulness in DCMs is attributed to this phenomenon
Specific therapeutic targets
RV dysfunction
RV dysfunction is responsible for systemic congestion .RV function improvement alone can improve the functional class in many .Controlling and targeting pulmonary hypertension is beneficial . There can be a role for off label use for chronic pulmonary hypertension associated with DCM.
Importance of weight reduction :
We can comprehend complex equations in cardiac failure , still we often forget a simple logic . Body wieght is an indirect but powerful determinant of aortic after load. A 80kg body needs more heart power than a body with a 40 kg mass. If a patient with EF of 25 % loses 50 % of his body mass, his heart can serve his body for 100 % longer duration. (Of course , this happens in certain patients by a mechanism called cardiac cachexia ! shall we call it as natural adaptation ? )
Inflammation control
Tumor necrosis factors and Interleukins are responsible for systemic reaction . These levels are high in CHF. Anti -Inflammatory drugs and diet would help. Statin usage is shown to be beneficial.
Metabolic modulation
ATPs ,fatty acid are fuels for the heart .Ailing hearts require it in plenty. Certain drugs like Trimetazidine, L carnitine has been shown to be useful .
Cardio-Renal syndrome
This is nothing but raising renal parameters as heart failure worsen .This essentially involves fluid and electrolyte management.
Natural course of refractory cardiac failure
It is sort of a delayed near death sentence . 5 year survival is comparable to many cancer inflicted patients.Basic medical care remain the corner stone. CRT /ICD* , LV assist devices are slightly more effective with substantial risks and cost involved. Indicated only for rich and insurance infested population who can tolerate both scientific and financial excesses.
ICDs* do prevent sudden electrical deaths.
There is a fundamental flaw of electrical and mechanical device concepts in refractory heart failure .It forgets , CHF is a systemic disease .A cardio centric approach rarely works to perfection .
Cardiac transplantation is the ultimate . It works well beyond any doubt. In best centers like Stanford 85 % for 5 year survival is expected. Heart transplantation is limited by donor availability and surgical infra structure.Total artificial heart is a distant dream , but will be definitely accomplished
Role of surgery
CABG ( Strictly Indicated only in absolutely deserving .The habit of revascularising scarred, akinetic DCMs to be abandoned )
Ventricular reduction( Batisda -seems to work only in Brazil!)
Mitral valve interventions
Some exotic interventions in cardiac failure
Image courtesey
http://www.paracormedical.com
Mitral splinting to reduce secondary mitral regurgitation in DCM
Newer drugs and experimental drugs
Nesiritide, (Synthetic Brain naturetic peptide ) Tolvapton ( Vasopressin antagonist) are used with varying success .
20 point bed side prescription tips for refractory failure.
- Correct the underlying causes and triggers.Try to correct any critical coronary lesion if any by PCI /CABG ( Not a major game changer ! )
- Restrict activities (Better to remain in class 3)
- Admit only if persistent class 4 .(Intermittent class 4 does not require admission )
- Do not try vigorously to move up to class 2 with inotropes you may end up in class 4 !
- Advice mild passive and active movements. (6 minutes walk > 300 -400meters)
- Educate the entire family / Ask them to shun Internet (Internet acquired half baked medical knowledge is more injurious to health )
- Restrict salt intake
- Continue Digoxin till toxicity develop or maximum dose is reached (Milrinone /Amrinone make no major difference )
- Optimse diuretics. Add Metalazone to Frusemide.
- Maintain good hemoglobin level (Erythropoitin does not work !)
- Add beta blockers in every one including many of the class 4 (Not necessarily Carvidilol)
- ACEI remain a key drug . Titrate to maximum tolerated dose. (Additional ARBs not much useful)
- Aldosterone antagonist has unique role (Anti-fibrotic ? ) Caution required in diabetic patients in monitoring renal function .
- At-least One metabolic modulator like Trimetazide could be tried (ATP utilisation amplified)
- Fatty acid metabolism enhancer L carnitine may be useful (Recall 1st year medical school basics . . . Heart thrives on fat energy more !)
- Nephrologist consult is recommended if electrolyte / ECF status fluctuations are more.
- Avoid dobutamine infusions unless patient insist.
- Narcotics like morphine can be used liberally in terminal heart failure (Both for hemo-dynamic and neural benefits )
- As far as possible do not send these patients to big tertiary hospital unless heart transplantation is planned.
- Don’t be a party in exhausting the personal finance resources of the patient by ordering exotic investigations . Let him not suffer from additional worry ! (By the way . . . having a hefty health insurance limit is not an excuse . Depleting it for futile purposes would make the national economy weaker ! )
Final message
Three principles of management in refractory cardiac failure
- Systemic approach is the key .
- De-mystifying cardio centric interventions is essential.
- Psychological support is vital .
Functional capacity has a poor correlation with LV contractile function . The skeletal muscle integrity , blood flow , and its metabolism has critical say in this. Optimal medications , properly regulated locomotion , weight reduction can have a major impact.
The secrets of living a good quality of life in cardiac failure , lies not in modern technology but in the rare commodities called common sense and compassion.
Dr.S.Venkatesan MD 