Structural heart disease without signs
or symptoms of heart failure (HF)
The ACC/AHA Stage B medical treatment guidelines include
Stage B treatment goals include all Stage A goals plus:
Coronary Artery Disease (CAD) is the most common type of heart disease in the United States. CAD is caused by atherosclerotic plaque in the walls of the coronary arteries. This plaque buildup can lead to stenosis, ischemia, angina and a sympathetic response that increases cardiac work load. Over time, CAD can weaken the heart muscle leading to heart failure, arrhythmia and death.
The plaque can rupture and lead to clot formation (thrombosis) severely blocking blood flow in the coronary arteries. Myocardial ischemia occurs rapidly.
"Brief periods of ischemia (<20 minutes) are reversible if followed by reperfusion. They are not associated with development of necrosis but result in the phenomenon of stunning. If duration of coronary occlusion is prolonged beyond this point, a wavefront of necrosis propagates from subendocardium to subepicardium. Reperfusion beyond a few hours does not reduce myocardial infarct size (Michiels 2004)."
If the blockage isn't treated quickly, within 20 minutes or less, the hypoxic tissue dies. Necrosis becomes visibly apparent within about 2-4 hours. Scar formation replaces the necrotic myocardial infarct (MI) tissue. It may take 5-6 weeks to fully form the scar . The resulting heart damage may not be obvious, or it may cause severe or long-lasting problems.
"In most patients with heart failure due to left ventricular systolic dysfunction, the underlying cause is coronary heart disease. To reduce progression to heart failure in a patient with acute myocardial infarction, it is important to achieve the earliest possible reperfusion, whether by thrombolysis or primary percutaneous coronary intervention (Dargie, 2005)"
Ventricular remodeling refers to the changes in size, shape, structure, and function of the heart.
Some of the early signs of LVH are
- Shortness of breath
- Chest pain, often after exercising
- Sensation of rapid, fluttering or pounding heartbeats (palpitations)
- Dizziness or fainting (Mayo clinic staff, 2016)
Causes and Tests
Besides hypertension LVH can be caused by aortic valve stenosis, hypertrophic cardiomyopathy and athletic training. An electrocardiogram, an echocardiogram and/or an MRI maybe ordered to confirm a diagnosis of LVH.
It is recommended that patients with structural heart disease be treated with ACE inhibitors or angiotensin II receptor blocker (ARB) and Beta blockers.
ACE inhibitors (ACE-Is) were initially designed to relax constricted blood vessels for patients with hypertension. ACE-Is have since been shown to reduce morbidity and mortality in patients at high risk for heart attacks and heart failure.
In a research article by Ricci, Castelnuovo, Savarese and Perrone Filardi (2016), both ACE-Is and ARBs were equal in their ability to prevent CV death, heart attacks, strokes, and new onset of HF.
Beta blockers, as stated in the previous section, are a classification of drugs that work by blocking the neurotransmitters norepinephrine and epinephrine from binding to receptors. Blocking these transmitters slows down heart rate and reduces the work load on the heart. They are often used to treat hypertension, arrhythmias and heart failure (Burchfield, 2013).
Comparing surgical outcomes with medical treatment
Before 2000, there were a number of studies that showed patients treated conservatively with medication for the same cardiac issues compared with surgical interventions had similar outcomes with slightly slower mortality rates in the medically treated group (Hueb, 1995; Thompson, Jabbour & Goldberg et al., 2000). Since then more studies have been carried out better defining the uses of both medical and surgical interventions.
Indications for surgical treatment:
- Stable angina with unrelenting and unbearable symptoms as well as unstable angina
- Extensive coronary heart disease
- High risk for future cardiac events
- Post myocardial infarction (Aroesty, 2016)
For more information go to http://www.uptodate.com/contents/coronary-artery-bypass-graft-surgery-beyond-the-basics. According to a study carried out by Boden et al. (2007) of 2,287 patients with stable coronary artery disease there were no significant differences in incidences of death, myocardial infarctions and stroke within 7 years between the patients who had a percutaneous coronary intervention (PCI – stent insertion) and those who had medical-therapy alone.
Velazquez et al. (2016) studied 1212 patients with ejection fractions of 35% or lower randomly assigned to treatment by medical therapy alone or medical therapy and surgery (CABG). The patients undergoing surgery with medical therapy fared better. A significant outcome event occurred in 58.9 % of the those with surgery compared with 66.1% without surgery. In the CABG group 76.6% of the patient died within a 9-year period compared with 87% of the medical-therapy only group.
According to Hawkes, Nowak, Bidstrup & Speare (2006) in a review article of outcomes of coronary artery bypass graft surgery, the authors concluded there is general agreement that CABG improves the prognosis of patients with left main coronary artery stenosis or stenosis of the three main coronary vessels (Cundiff, 2001; Hlatky et al, 2004). However, without severe coronary artery disease the prognosis is good with medical treatment alone (Kirklin et al, 1991; Caines et al, 2004). With current and future improvements in both surgical procedures and medical therapy comparative studies will be ongoing.
Coronary artery bypass graft (CABG)
Coronary artery bypass graft (CABG) is a cardiovascular surgery intended to improve cardiac perfusion by anastomosing a relocated artery or harvested vein distal to a coronary artery occlusion thereby delivering blood to ischemic tissues.
Indications for CABG
- CABG may provide Diabetes mellitus patients improved survival over percutaneous coronary intervention (PCI)
- Ongoing ischemia or hemodynamic compromise after PCI
- Significant stenosis and unacceptable angina despite medical therapy
- Significant stenosis when medication is contraindicated
- Left main coronary artery disease
- Three-vessel disease with or without proximal Left anterior descending (LAD) artery disease
- Two-vessel disease with proximal LAD artery disease
- Two-vessel disease without proximal LAD artery disease
- Single-vessel disease with proximal LAD artery disease
- Single-vessel disease without proximal LAD artery disease
- LV Dysfunction
- Survivors of sudden cardiac death with presumed ischemia-mediated VT
Types of CABG procedures.
There are several types of coronary artery bypass grafting (CABG). The traditional CABG is used typically when a major coronary artery needs to be bypassed. During this procedure the chest bone is opened and the heart is stopped. A heart-lung bypass machine oxygenates and circulates the blood throughout the body. Surgery is performed on a still heart. Occasionally a mild shock is needed to start the heart after the reconnection. This surgery typically takes 3 to 6 hours.
On occasion a bypass grafting procedure is done with the chest bone opened but without the use of the heart-lung bypass machine. Sometimes this is referred to as an off-pump coronary artery bypass grafting or beating heart bypass grafting.
Another option is a percutaneous coronary intervention (PCI) also referred to as a coronary angioplasty. This is a nonsurgical procedure that opens a blocked or narrow coronary artery. A stent, a small mesh tube, might be put in place during the procedure to keep the artery open. Both procedures improve the pumping action of the heart muscle.
Patients need to be informed about the risks for all these surgeries. The risks, like most surgeries, include wound infection, bleeding, reactions to anesthesia, fever, and pain. However, with heart surgeries stroke, heart attack or even death may occur. Memory issues have also been cited as occurring.
Patients who are older, have diabetes and other health issues, like kidney disease, are more likely to have complications. These procedures done on emergency basis, particularly post heart attack, also carry a higher risk.
The mortality rate for patients having coronary artery surgery is between 2% to 3.3% annually. This will vary depending upon the frequency of the number of procedures performed by the surgeon and the number of vessels operated upon. Hospitals which have surgeons and staff who carry out these procedures with great frequency generally have lower morbidity and mortality rates.
Heart valve surgery
Heart valve surgery is used to repair or replace diseased heart valves. As shown earlier in the course there are four valves in the heart:
- Aortic valve
- Mitral valve
- Tricuspid valve
- Pulmonic valve
Healthy valves control the flow of blood forward and prevent backward flow. The mitral valves and aortic valves are the ones most commonly operated upon. The mitral valve is most often repaired. The aortic valve to date has not been able to be repaired so it is replaced with a new valve. The tricuspid or pulmonic valves are rarely replaced or repaired.
- Aortic insufficiency
- Aortic stenosis
- Congenital heart valve disease
- Mitral regurgitation - acute Mitral regurgitation - chronic
- Mitral stenosis
- Mitral valve prolapse
- Pulmonary valve stenosis
- Tricuspid regurgitation
- Tricuspid valve stenosis
Valve surgery can involve a cut through the breastbone and a connection to a heart-lung bypass machine or pump. Less invasive valve surgery can be done with smaller incisions or the use of a catheter (Percutaneous). With mitral valve surgery the surgeon can repair the ring-like part around the valve or trims or rebuilds one or more of the leaflets. In the case of valve replacement typically done on the aortic valve either a mechanical or biological (made of human or animal tissue) is used. The mechanical valves require the patient to take blood thinners where the biological ones do not. The mechanical valves rarely fail. Valves may last up to 20 years. Usually the results are good with excellent symptom relief. A 5 to 7-day hospital stay is usually required.
Mortality rate for heart valve surgery is about 1.7% according to the Society of thoracic Surgeons. The most common risks include heart attacks. Irregular heartbeat (arrhythmia), kidney failure, post-pericardiotomy syndrome - low fever and chest pain that can last for up to 6 months - stroke or other temporary or permanent brain injury Temporary confusion after surgery due to the heart-lung machine can also occur.
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This content will be reviewed or retired by 1/2019