EKG, CPR, and Cardioversion

ECG/EKG

ECG is the recording of hearts electrical activity through repeated cardiac cycle, says Wikipedia. With each heartbeat, the heart undergoes depolarization, initiating its contraction. This electrical activity spreads through the body and can be detected on the skin, forming the basis for the ECG (electrocardiogram). The ECG machine interprets signals from electrodes on the skin to create a visual depiction of the heart's electrical activity. Its basic pattern follows:

Electrical activity towards a lead result in an upward deflection.
Electrical activity away from a lead result in a downward deflection.

Depolarization and repolarization deflections occur in opposite directions.

In ECG terminology, the word "lead" can refer to two things:

The cable that connects an electrode to the ECG recorder.
The electrical view of the heart obtained from any particular combination of electrodes.

The interpretation should include ‘RRAPPQ’

R- rate= regular/irregular
R- rhythm= NSR/irregular
A- axix= normal/ LT axis deviation/ RT axix deviation/extreme RT axix deviation/ no man’s land/ Northwest
P- P-wave= normal in lead II/ normal p amplitude in v1
P- PR interval= normal/heart block/WPW syndrome
Q- QRS complex= voltage=high/low; twist around the isoelectric line (Torsades de pointes TdP); LBBB or PM (sagarbossa criteria).

The electrical axis, which represents the sum of all electrical currents generated by the ventricular myocardium during depolarization, is a crucial aspect of interpreting an electrocardiogram (ECG). Analyzing the axis can provide valuable information about cardiac conditions such as ventricular hypertrophy, bundle branch blocks (BBB), and changes in the position of the heart within the chest cavity (e.g., due to pregnancy or ascites). This information aids in determining the location and extent of cardiac injury, guiding diagnosis and management decisions.

The period from the onset of the P wave to the beginning of the QRS complex is indeed called the P-R interval or PQ interval. It typically ranges from 0.12 to 0.20 seconds in duration. Some electrocardiographers prefer the term "PQ interval" because it reflects the period actually measured unless the Q wave is absent.

Contrary to common belief, the PR interval does not solely represent the time it takes for the signal to move from the sinoatrial (SA) node to the atrioventricular (AV) node. Instead, it encompasses the time required for the propagating impulse to travel from the atria through the AV node, bundle of His, bundle branches, and Purkinje fibers until the ventricular myocardium begins to depolarize. Importantly, it does not include the duration of conduction from the SA node to the right atrium (SA conduction).

The direction of the QRS complex in leads I and aVF determines the axis quadrant in relation to the heart.

ECG TYPES AND REPORTING

There are 3 major types of ECG, they are: resting ECG, ambulatory ECG and stress test ECG.

An ECG report can be categorized into three types of services:

Technical aspect only: This involves the recording and processing of the ECG signals without interpretation or a written report.
Interpretation and written report only: In this service, the ECG signals are analyzed, interpreted, and a written report is generated without including the technical aspects of recording.
Both aspects together as one service: This comprehensive service includes both the technical recording and processing of ECG signals, as well as the interpretation and generation of a written report.

ECG Vs Rhythm strip

In an ECG, the electrical activity of the heart is observed from different electrical axes, with each viewpoint referred to as a "lead." A standard ECG views the heart from 12 axes, resulting in 12 leads. However, a rhythm strip usually includes one to three leads for a more focused observation.

Typically, a full 12-lead ECG is documented as a separate report from the medical progress notes. In contrast, a printed rhythm strip, which may include one to three leads, can be pasted directly into the progress notes for reference.

ECG coding guidelines:

★ The relevance of ECG results to patient management is paramount.

★ When an ECG is performed on the same day as a cardiac stress test but is not part of that stress test, it should provide additional information to justify separate payment. For instance, an ECG may be necessary to rule out an acute myocardial infarction (MI) before a same-day stress ECG is conducted to evaluate possible accelerating angina. However, if the ECG stress test is scheduled in advance, a separate ECG on the same day may not be deemed reasonable and necessary, as it is expected that all necessary testing would be included in the planned procedure.

★ For Medicare beneficiaries, an ECG is typically not covered when used for screening purposes or as part of a routine physical examination. Medicare does not cover routine physical examinations, including screening services, when there are no associated signs, symptoms, or complaints. These services are considered not to be benefits of the Medicare program. However, patients have the option to pay privately for these services if they wish to undergo them outside of Medicare coverage.

★ A second ECG performed to replace a technically inadequate ECG cannot be reported as an additional service.

★ Rhythm ECGs are specifically utilized to assess signs and symptoms indicative of a cardiac rhythm disorder.

★ When it comes to billing, a rhythm ECG interpretation and report (93042) is already included in a 12-lead ECG interpretation and report (93000 or 93010). Similarly, a rhythm ECG tracing (93040 or 93041) is included in a 12-lead ECG tracing (93000 or 93005). This streamlines the billing process and avoids double-billing for overlapping services.

★ When multiple ECG rhythm (or monitor) strips from a single date of service are reviewed at one time, only one unit of service should be reported, regardless of the number of strips reviewed. This ensures that the billing accurately reflects the work performed during the review process, streamlining the billing process and avoiding overbilling for multiple units of service for the same activity.

★ If one physician bills for a rhythm strip interpretation and another physician bills for an ECG interpretation for the same patient on the same date of service, both services must be deemed reasonable and necessary. This situation often arises when the patient requires prolonged rhythm monitoring in addition to a 12-lead ECG. Each service should reflect the specific needs of the patient and the professional judgment of the physicians involved in their care.

★ When an ECG is furnished on an emergency basis by a laboratory or a portable X-ray supplier, it is necessary for a physician to be in attendance at the time the service is performed or immediately thereafter. This ensures that the ECG can be interpreted promptly, and appropriate medical decisions can be made based on the results. Having a physician present or available immediately ensures timely and accurate interpretation and management of the patient's condition.

★ Payments for a home-based ECG that exceed the base amount, such as for transportation costs, require a medical necessity for performing the service in the patient's home, beyond the need for the ECG itself. Typically, qualifying patients for home-based ECG services will be homebound or bed-confined, meaning they have difficulty leaving their home or are confined to their bed due to their medical condition. This additional requirement ensures that Medicare resources are allocated appropriately and that patients receive necessary care in their home environment when it is medically necessary and justified.

★ Payment for the technical component of an ECG will be denied when the facility, such as a nursing home, is already paid for the technical component through the fiscal intermediary, typically during a Part A covered nursing home stay. In such cases, the ECG supplier is paid by the facility under a contract arrangement, and billing for the technical component separately to Medicare would result in duplicate payment for the same service. This helps prevent overpayment and ensures proper allocation of Medicare funds.

ECG changes in different cardiac conditions

Lead AVR on ECG:

Acute Myocardial Infarction: ST elevation > 1.5 mm in AVR indicates left main coronary artery (LMCA), left anterior descending (LAD), or 3-vessel coronary disease. It's associated with high mortality and refractory cases.
Pericarditis: PR elevation in AVR suggests subepicardial atrial injury from pericardial inflammation. Differential diagnosis includes ACS vs pericarditis, with concurrent PR elevation in AVR favoring pericarditis.
Tricyclic Antidepressant (TCA) & TCA-like Overdose: Prominent R wave in AVR is a classic EKG finding. It's associated with sinus tachycardia, widened QRS and QTc interval, and RAD 130°-170°. An R/S ratio in AVR > 0.7 predicts arrhythmia.
Atrioventricular Reentry Tachycardia (AVRT) in WPW: ST elevation in AVR in narrow complex tachycardia suggests AVRT in WPW. It's more sensitive for AVRT in WPW than other conditions.
Differentiating Ventricular Tachycardia (VT) from Supraventricular Tachycardia (SVT) in Wide Complex Tachycardia: Vereckei criteria, focusing on AVR lead, is more sensitive in detecting VT than Brugada criteria.

Brugada syndrome

Brugada Syndrome is an ECG abnormality associated with a high risk of sudden death in individuals with structurally normal hearts, often due to a mutation in the cardiac sodium channel gene. ECG diagnosis includes Type 1 (Coved ST segment elevation >2mm in >1 of V1-V3 followed by a negative T wave), which is potentially diagnostic, and Types 2 and 3, which may warrant further investigation. Management involves implantation of an automatic implantable cardiac defibrillator (ICD) to treat ventricular tachycardia and fibrillation and prevent sudden death, as no pharmacologic therapy has been proven effective. However, drugs like quinidine could theoretically counteract the ionic current imbalance in Brugada syndrome.

ECG changes in PE

The mechanism of ECG changes in Pulmonary Embolism (PE) involves acute strain on the right heart due to increased pulmonary artery resistance. This can lead to dilation of the right ventricle and atrium, right ventricular ischemia, and sympathetic nervous system stimulation. Possible ECG changes in acute PE include sinus tachycardia, complete or incomplete right bundle branch block (RBBB), right ventricular strain pattern with T wave inversions in right precordial leads and inferior leads, right axis deviation, dominant R wave in V1, right atrial enlargement (P pulmonale), SI QIII TIII pattern, clockwiserotation, atrial tachyarrhythmias, non-specific ST segment and T wave changes, and simultaneous T wave inversions in inferior and right precordial leads. However, ECG is neither specific nor sensitive for PE, but it may be one of the first indications of right ventricular overload. About 18% of patients with PE may have a completely normal ECG.

Normal LBBB in ECG

Left Bundle Branch Block (LBBB) alters the normal direction of septal depolarization, resulting in specific ECG changes. In LBBB, the QRS duration is prolonged (>120 ms), there is a dominant S wave in V1, a broad monophasic R wave in lateral leads (I, aVL, V5-V6), and absence of Q waves in lateral leads (except small Q waves in aVL). Additionally, prolonged R wave peak time (>60 ms) may be observed in left precordial leads (V5-V6).

In the context of ischemic LBBB, there are challenges in diagnosing ischemia due to both imitation and masking effects. LBBB can cause secondary ST-T changes, including ST-segment elevations in V1-V2 and ST-segment depressions and T-wave inversions in V5, V6, aVL, and I. However, LBBB may also mask actual ischemic ST-T changes, making diagnosis challenging. It's important to recognize that new LBBB in patients with chest discomfort may indicate a high probability of acute coronary artery occlusion, necessitating management as patients with ST-segment elevation myocardial infarction (STEMI) or ST-segment elevation acute coronary syndrome (STE ACS). If there are no previous ECG recordings available, one must presume that the LBBB is new.

ECG changes caused by pericardial effusion and cardiac tamponade

Pericardial Effusion:

Low voltage: Large amounts of pericardial effusion diminish QRS amplitudes.
Electrical alternans: QRS complex amplitudes vary from beat to beat in the same lead due to swinging of the heart in the pericardial space. Note that tachycardia, pulmonary embolism, and ischemia may also cause electrical alternans.
PQ segment depression.
Sinus tachycardia.
Cardiac Tamponade:
Clinical presentation: Patients may complain of dyspnea and chest pain. Physical examination may reveal muffled heart sounds, jugular venous distention (JVD), and hypotension (Beck's triad), along with pulsus paradoxus.
ECG findings: Low voltage QRS complexes and electrical alternans may be observed.
Echocardiography: Diastolic collapse of the right ventricle can be visualized.
Treatment: Pericardiocentesis is the mainstay of treatment.
Recognition of these ECG changes and clinical features is crucial for prompt diagnosis and management of pericardial effusion and tamponade.