Heart Failure

Introduction:

Heart Failure (HF) continues to be a major heart problem and an important cause of hospitalization in India. The number of patients with HF has been gradually increasing due to improving life span of patients and improved survival after heart attacks in the last few years. More patients are being saved from heart attacks due to better availability of drugs and immediate revascularization of the blocked vessels. Though this is heartening news, the number of patients with poor heart function has been increasing all over the country.

What is Heart Failure?

Heart Failure does not mean that heart has stopped working or is about to stop working. HF is a condition in which the heart becomes so weak that it has trouble pumping a normal amount of blood carrying enough oxygen and nutrients to meet the body’s needs.

 

What causes HF?

HF develops either as a result of (1) damage to the heart muscle (which could be caused by coronary artery disease,  infection or toxic exposure to chemicals such as alcohol and drugs) or (2) when too much strain is placed on the heart because of years of untreated high blood pressure or an abnormal heart valve.

 

What is the commonest cause of Heart Failure/ heart muscle damage?

The commonest cause of HF is coronary artery disease where in the blockages of the coronary arteries cause damage to the heart muscle thereby reducing the pumping of the heart. The loss of pumping function of the heart is directly related to how fast the patient seeks treatment for a heart attack. Patients who receive treatment within one hour of onset of chest pain due to a heart attack do well as the heart muscle is salvaged from further damage due to early intervention in the form of drug treatment or angioplasty. Damage to the heart muscle due to drugs, alcohol or infections is the second common cause of HF.

 

What do the patients complain of?

The commonest symptom is shortness of breath, also called dyspnea, which is caused by accumulation of fluid in the lungs due to failure of the left side of the heart.

Swelling of feet, ankles, legs and abdomen due to accumulation of fluid is caused by failure of the right side of the heart.

Chronic cough, loss of appetite and fatigue are some of the symptoms which patients experience.

Some of the patients may complain of palpitations which may be caused by irregular heart beats.

 

Diagnosis of HF:

Patients are mostly diagnosed by their physicians due to their typical symptoms and then advised to undergo tests like Electrocardiogram, Echocardiography and Coronary angiography.

  1. The Electrocardiogram (ECG) give information about the rhythm of the heart, any electrical disturbance of the heart and also if the blood supply is less.
  2. The Echocardiography is the sonography of the heart wherein its imaged and the pumping of the heart is studied. It’s the most important test to diagnose heart failure. It gives the physician information on heart pumping, the function of the valves and leaks across the valves. The pumping of the heart can be quantified as Ejection Fraction (EF) which is normally in the range of 55-65%. Any decrease in EF below the normal range suggests some weakness of the heart muscle and needs to be investigated further. Patients with EF lower that 35% entail more risk of sudden death and heart failure hospitalizations and need more specialized treatment.
  3. Coronary angiography: is necessary to diagnose blockages in the coronary arteries which would need subsequent correction by either angioplasty or bypass surgery.

 

Risks of Heart Failure:

Patients with HF are at high risk of Sudden Cardiac Death and recurrent hospitalizations due to heart failure episodes. The patients at most risk are the ones with an EF of less than or equal of 35%. HF patients keep getting admitted in hospitals due to recurrent dyspnea which need to be treated with intravenous medications.

 

Devices in Heart Failure:

There are 2 devices which can be used in HF treatments (1) Cardiac Resynchronization Therapy and (2) Implantable Cardiac Defibrillator

 

 

Summary:

Patients with heart failure are at risk of dying from progressive heart failure and sudden cardiac arrest. This can be now corrected and treated effectively by implanting devices (namely CRT and ICD respectively). However, these patients need to be carefully evaluated and selected by the cardiologist before undergoing these procedures so as to ensure maximum benefit.

 

 

Devices for Heart Failure

Devices for Heart Failure:

 

There are 2 devices which can be used in HF treatments (1) Cardiac Resynchronization Therapy and (2) Implantable Cardiac Defibrillator

 

(I) Cardiac Resynchronization Therapy:

The heart is made of 2 upper chambers called atria and 2 lower chambers called ventricles. An electrical system controls the synchronized pumping action of these chambers. The atria contract first followed by the 2 ventricles. The 2 ventricles contracts simultaneously to as to ensure optimal pumping of blood to the body and lungs. However this synchronized contraction (Synchrony) is lost between the atria and the ventricles and also between the 2 ventricles. This dys-synchrony leads to further less effective contraction of the heart thereby reducing thereby aggravating the heart failure. This Dys-synchrony can be easily diagnosed by the Physician with the help of the electrocardiogram and the echocardiogram.
CRT is designed to correct this dys-synchrony between the upper and lower chambers of the heart and also between the 2 lower chambers. This ensures simultaneous contraction of the 2 lower chambers thereby improving the contractions. In this procedure, a pacemaker (the size of a pager) is implanted just below the skin in the upper chest region and 3 wires (leads) are inserted into the heart to deliver electrical therapy. The 3 leads are positioned in the right upper, right lower chambers and the left lower chambers. The CRT device simultaneously stimulates the left and right ventricles and restores a coordinated, or “synchronous,” squeezing pattern. This reduces the electrical delay and results in a more coordinated and effective heart beat.

Who needs the CRT?
According to the Heart Rhythm Society, the ideal candidate for a CRT device is someone with:

  1. Moderate to severe heart failure symptoms, despite lifestyle changes and medication
  2. A weakened and enlarged heart muscle
  3. A significant electrical delay in the lower pumping chambers.

How effective is CRT?

There have been around 8-9 clinical trials involving around 5000 patients. Clinical studies demonstrate modest improvements in exercise tolerance, heart failure severity, and quality of life in most patients. Almost two-third of the patients implanted with the device benefit in their symptomatic status and also have decrease in the number of hospitalizations over the next few years. Improvement may happen quickly, but sometimes it can take several months.

(II). Implantable Cardiac Defibrillators (ICD)

ICD is a device designed to shock the heart out of a dangerous life threatening rhythm. The device is similar to the pacemaker and is the size of a pager. It is implanted below the skin in the upper chest and is then connected to a wire (lead) which monitors the heart rhythm 24 hours. Whenever it detects a dangerous heart rhythm, it delivers an internal shock to the heart and restores the normal rhythm.

Who needs ICD? Who is at risk of developing dangerous heart rhythm?

Dangerous heart rhythms can cause Sudden Cardiac Arrest which can cause instant death. Patients most at risk are those with compromised heart function (Ejection fraction < 35%). These patients if symptomatic need to undergo an ICD implantation so as to reduce their risk of dying from sudden cardiac arrests.

How effective is ICD?

There have been around 6 clinical trials involving around 3000 patients. Clinical studies demonstrate modest reduction in the death rates due to sudden cardiac arrest and have been life-saving in the majority of the patients.

Summary:

Patients with heart failure are at risk of dying from progressive heart failure and sudden cardiac arrest. This can be now corrected and treated effectively by implanting devices (namely CRT and ICD respectively). However, these patients need to be carefully evaluated and selected by the cardiologist before undergoing these procedures so as to ensure maximum benefit.