Welcome to the Basic Cardiology area of our Patient Education section. This section is designed for you to educate yourself on some basic cardiology terminology. All of the topics listed in this section will have some information for you to read.


The heart is a muscular pump about the size of your fist and its primary function is to pump oxygenated blood to the rest of the body. It is made up of four chambers, the right and left atria on the top, and the right and left ventricles on the bottom. The septum is a thin muscular wall that separates the right and left sides of the heart. Each contraction of the heart occurs in response to a electrical impulse that starts in the upper portion of the heart. Blood is moved in a closed circuit through the body by the pumping of the heart. The heart contracts and pumps blood out to the body (systole) and relaxes to fill with more blood (diastole).
The heart muscle itself is like all other organs in the body and requires oxygen to function. The oxygen-rich blood is circulated to the heart muscle through the coronary arteries. There are two main arteries: the right coronary artery and the left main coronary artery, both starting at the aorta (the main blood vessel of the body). These vessels then branch off into smaller and smaller vessels along the surface of the heart.

In studying and testing the heart, it is important to understand which system in the heart is having problems:

  1. 1. Electrophysiology - Is the conduction system (the wiring) in the heart following the normal pathway?
  2. 2. Coronary circulation - Is the heart muscle getting adequate blood supply and oxygen through the coronary arteries (the plumbing)?


Cardiac contractility, or pumping ability, is an important part of heart function. The heart's conduction and circulatory systems may be fine, but if the heart muscle doesn't contract well, significant symptoms can result.

We can assess contractility through an echocardiogram which is an ultrasound test of the heart. Many things can affect how well the heart contracts. These include certain medications, heart attacks, overuse of alcohol, and cardiomyopathy (primary heart muscle disease). The causes of decreased contractility and/or alternatively “stiff” heart muscle, and their treatment options should be discussed with your cardiologist.

The RCA supplies blood to the bottom (inferior) portion and part of the back (posterior) portion of the left ventricle. The posterior portion of the septum, separating the ventricles, is also supplied with blood from the RCA.
The LAD supplies blood to the front (anterior) portion of the left ventricle, including most of the anterior portion of the septum separating the ventricles.
The LCX supplies blood to the left side (lateral) portion and the back (posterior) portion of the left ventricle.

In order to perform work, the heart, like all other organs in the body, needs oxygen and nutrients. The heart has its own special circulation, the coronary arteries, of which there are two: the right coronary artery (RCA) and the left coronary artery (LCA). The left coronary artery divides into the left anterior descending (LAD) branch and the left circumflex branch. The right coronary artery and the branches of the left coronary artery provide numerous smaller branches that penetrate the heart muscle, supplying it with blood. Both coronary arteries originate from the main blood vessel of the body, called the aorta, and run along the surface of the heart. In the majority of human hearts, coronary circulation follows a predictable pattern.

Diagnostic procedure performed in the hospital, whereby a catheter (usually is passed through an artery in the wrist or sometimes in the groin) which is advanced to the heart’s arterial vessels and contrast dye is injected to assess for “blockages” or plaque that may or may not obstruct blood flow. If the blockage requires opening, then a stent can be deployed within the blockage. On occasion, a right heart catheterization (catheter placed through a vein in the groin) may also be performed to assess the heart’s right sided filling pressures.

If the coronary arteries and veins are considered the plumbing of the heart, then the conduction system (shown in black below) can be considered the electrical wiring of the heart. Through this wiring, each muscle fiber of the heart knows when and how fast to beat so that the heart can pump efficiently.

The electrical system of the heart is greatly affected by the brain and by certain hormones and body chemicals called electrolytes. How these elements work with the rhythm generators of the heart determines the heart rate and sequence of the heartbeat. The sino-atrial (SA) node is the body's main natural cardiac pacemaker. The heartbeat starts here and spreads like the ripples in a pond throughout the network of conduction fibers in the two atria (the two upper chambers), causing them to contract. Normally, the heartbeat can only reach the ventricles (the two lower chambers) after it has passed through the atrioventricular (AV) node. The AV node slows down the electrical signal so that the atrial contractions can finish and fill the ventricles more completely. The AV node also prevents the lower chambers from beating too fast if the atria develops a fast rhythm (tachyarrhythmia). The electrical signal finally passes to the ventricles, the main work horses of the heart, through the bundle of His, bundle branches, and the Purkinje system (a specialized network of nerves that coordinates contraction of the ventricles). Each heartbeat is then completed and a new one is initiated in the SA node.


Being able to assess and measure how the heart is functioning without entering the body is called noninvasive cardiology. Non-invasive cardiology uses ultrasound waves to examine the heart (an echocardiogram). An echocardiogram can provide information on contractility, valve function, blood flow through the heart and other vessels, and evaluation of any clots that may have formed in the chambers of the heart. The findings from this test can answer some questions or tell us if further tests are indicated.

Before a cardiac catheterization (angiogram) is ordered, you may have a form of stress test ordered. Exercise or stress testing is used to determine exercise capacity and to monitor cardiac arrhythmias. A stress test can also determine if myocardial ischemia (lack of oxygen to the heart muscle) is the cause of chest pain for the patient.

Several tests in this field may be used:


Hospital based procedure in which a device implanted to treat symptomatic slow heart rhythms/rates.

Patients with very slow heart rhythms, bradycardias, may need to have a permanent pacemaker inserted. The main reasons a pacemaker would be required are:

  1. 1. Blocked or injured areas in the conduction system caused by normal aging or following an ablation.
  2. 2. A combination of fast and slow heart rates requiring medications to control the fast rhythms and a pacemaker to prevent the slow rhythms.

How Pacemakers Work

If you have any questions regarding your pacemaker checks you can reach us at 410-761-8007.

Procedure performed in the hospital setting, typically for symptomatic atrial arrhythmias, such as atrial fibrillation. Sometimes a (TEE) transesophageal echo (special echo involving the passing of a small thin ultrasound tipped probe down the esophagus) is used to exclude any blood clots in the heart prior to the procedure. The patient is completely sedated and a shock is delivered through electrode pads (placed on the front and back of the chest) which help in the restoration of a normal rhythm. In some instances the patient may need to be admitted for a few days on a cardiac telemetry floor (in order to be monitored for side effects), in order to be started on special heart rhythm medication used to help sustain a normal rhythm.

An ICD is an implantable device (somewhat similar to a pacemaker) that not only has pacemaking function, but also has the ability to treat potentially harmful rapid arrhythmias that arise from the ventricles (bottom of the heart) using rapid ventricular pacing and/or internal shocks from a wire placed in the heart such as from a Transvenous Implantable Cardioverter Defibrillator (TV-ICD) or a Subcutaneous Implantable Cardioverter Defibrillator (S-ICD) that uses shocks from a wire placed subcutaneously in the chest, outside of the heart

CRT is the ability to pace the left ventricle, thereby restoring more physiologic contraction of the heart in patients with chronic systolic congestive heart failure and marked left bundle branch block. The additional special lead may be placed with an ICD creating a Biventricular Implantable Cardioverter Defibrillator (BIVICD or CRT-D) system or a PPM creating a Biventricular Permanent Pacemaker (CRT-P) system

ILR is a very small device placed under the chest wall skin that may stay for up to a few years (removed subsequently) that is used to help record/diagnose arrhythmias over a long period of time

An EPS is a diagnostic procedure using electrode-tipped catheters, placed in the heart, to help assess the electrical status/function of the heart, diagnose arrhythmias (abnormal heart rhythms) and possibly treat rapid arrhythmias using ablation therapy.

LAA occlusion device, such as the WATCHMAN, is a implantable device placed in the heart using a catheter, that is used to reduce the risk of stroke in patients with a history of atrial fibrillation. It is primarily used in patients having an appropriate reason to seek a non-drug alternative to warfarin.


Established Patients

If you are an established patient and would like to make or change your appointment, please call us at 410-761-8007 and tell us the following:

We routinely call to confirm patient appointments 1-2 days in advance of your appointment. If you do not hear from us and believe you have an appointment, please notify us at 410-761-8007.

New Patients

Welcome to Maryland Heart Associates. The following will help you in setting up your first appointment.
Please call us at 410-761-8007 and tell us the following:

Once we have made the appointment, you will need to visit the Forms section of our website, print and complete the forms listed below, and have them with you on the day of your scheduled visit. If you have any questions, please contact the office that you are scheduled to visit.

For your first visit with us, it is important that you bring the following information with you:

If this is your first visit to Maryland Heart Associates, you will need to arrive 30 minutes prior to your scheduled appointment time for registration/completion of new patient paperwork.


If you are having a life threatening medical problem, please call 911 immediately.

If you are having an urgent medical problem, please call our office at (410) 761-8007.


Before seeing you, your physician may ask that you complete certain lab tests. It is best that you complete them no more than a week before your visit so that they are current. Please make sure that your chosen lab faxes the results to our office at (410) 766-8677.

When our medical staff receives the lab results, we will review them with the physician. If there are any pertinent, urgent, abnormal values, we will call you. If the values are normal, you will not receive a phone call. If you have any questions about this, please call one of our patient care representatives at (410) 761-8007.


An Implantable Cardioverter Defibrillator (ICD) is a small, electronic, potentially lifesaving device that is implanted inside the body. An ICD continuously monitors a patient's heartbeat. If it senses a dangerous, rapid heart rhythm, it delivers one or more pulses or shocks to the heart to restore a more normal rhythm. Patients are monitored in our ICD clinic every three months to make sure that the ICD is functioning correctly.
If you have any questions concerning your device, please call (410) 761-8007.