PREMATURE VENTRICULAR CONTRACTIONS
Premature ventricular contraction (PVC) occurs when the heartbeat is initiated by Purkinje fibers in the ventricles instead of the sinoatrial node. The PVC can be easily distinguished on an EKG. Although a PVC can be a sign of decreased oxygenation to the myocardium, PVCs are often benign and may even be found in healthy hearts. A PVC may be perceived as a skipped beat or palpitations. Normally, the ventricles contract after they have been filled by the atria. The ventricles then pump the maximum amount of blood to the rest of the body. In a PVC, the ventricles contract before they are maximally filled by the atria. The heart is unable to pump an adequate amount of blood to the rest of the body. Single beat PVCs do not usually pose a threat to the patient and can be asymptomatic.
PVCs can occur at any age but are more prevalent in the elderly and in males. They may occur without a precipitating cause. However, some causes of PVCs include adrenaline excess, calcium excess, cardiomyopathy, digoxin, electrolyte imbalances, drugs such as alcohol, caffeine and cocaine, heart attack, hypoxia, hypercapnia.
Signs and symptoms associated with PVCs are a skipped heart beat or a strong beat. They may be associated with chest pain, feeling like fainting, fatigue or hyperventilation. PVCs can exacerbate and cause ventricular tachycardia. Patients often present with a feeling of skipped beats. A physical exam and full history should be taken. Physical exam can determine heart defects, for eg, mitral valve prolapse, that might cause the palpitations. A 12 lead EKG may be done, but it is often inconclusive as there is a small chance of a PVC occurring during the time the EKG is done. Holter monitoring may be better as it is a continuous recording of the heart’s rhythm over a period of 24 hours. The chance of a PVC recurring during this period is higher.
On and EKG, PVCs have a distinctive look. The spacing between the PVC and the preceding wave is shorter than normal and the subsequent QRS wave stays the same as normal due to compensatory pause. PVCs can be distinguished from premature atrial contractions because the compensatory pause is longer following PVCs.
There are four patterns of regularly occurring PVCs depending on the number of normal beats between each PVC. The rhythm is called bigeminy (1 beat), trigeminy (2 beats) or quadrigeminy (3 beats). Unifocal PVCs are triggered from a single site in the ventricle, causing the peaks on the EKG to look the same. Multifocal PVCs arise from multiple sites, causing each peak to have a different shape.
Isolated PVCs with benign characteristics require no treatment. In most healthy individuals, PVCs can be resolved by stopping the offending agent, such as drugs and caffeine, and restoring the balance of calcium, magnesium and potassium in the body. Pharmacologic agents such as antiarrhythmics, beta blockers and calcium channel blockers may be used. In the case of persistent PVCs, radiofrequency ablation can be considered. PVCs must be monitored carefully if the patient has existing heart disease as they can cause ventricular tachycardia. Patients who experience extremely high occurrences of PVC (several thousand a day) can develop dilated cardiomyopathy. If the PVCs are reduced or removed, the cardiomyopathy usually regresses.
Dr. Ben-Zur is a cardiologist who sees patients from Burbank, Encino, Sun Valley, Beverly Hills, Brentwood, Marina del Rey, Inglewood, El Segundo, Manhattan Beach, Redondo Beach, Torrance, Hollywood, Bel Air, Malibu, Calabasas, Saratoga Hills, Agoura hills, Thousand Oaks, Sherman Oaks, Studio City, Simi Valley, West Hills, Reseda, and Oak Park. He sees patients with all types of heart disease, including atrial fibrillation, a-fib, AF, sick sinus syndrome, av block, heart block, arrythmias, ischemia, congestive heart failure. He places pacemakers, defibrillators, implantable cardiac defibrillators. Bi-ventricular pacing.