From Normal Sinus to Ventricular Tachycardia Arrest - The Sinister Role of Obstructive Sleep Apnea
Mr. WA is a 74-year-old morbidly obese Caucasian male with a calculated body mass index (BMI) of 45. His past medical history is significant only for hypertension and obesity. He was first diagnosed with atrial fibrillation in March of 2012 (Fig 1 and 2) after presenting to his PCP's office with palpitations. He underwent direct current cardioversion after a TEE showed absence of left atrial appendage thrombus. His left ventricular ejection fraction was noted to be normal at that time. He was subsequently discharged to home with a remote cardiac monitoring device. Ten days post discharge his rhythm again reverted to atrial fibrillation and multiple PVC's along with episodes of nonsustained ventricular tachycardia were noted (Fig.3). Interestingly, remote monitoring also demonstrated significant slowing of the ventricular rate associated with multiple 4 second long pauses during the night (Fig. 4). He was again admitted with the aim of repeating cardioversion and initiating antiarrhythmic therapy. However, he developed a wide complex tachycardia presumed to be ventricular tachycardia (Fig 5) and suffered a cardiac arrest. After successful resuscitation and initiation of antiarrhythmic therapy an ICD was implanted.
Because of the association of obstructive sleep apnea with cardiac dysrhythmias, his elevated BMI and admitted daytime sleepiness, polysomnography was performed. This confirmed the presence of poor sleep architecture, nocturnal hypoxemia and severe OSA. He was prescribed bi-level PAP therapy initiated at IPAP 12, EPAP 8 and 2L of oxygen. Since initiating this therapy his monitoring ICD has not recorded any ventricular arrhythmias. His atrial fibrillation and frequent PVC's have not recurred.
Ventricular arrhythmias and sudden cardiac death associated with obstructive sleep apnea usually occur at what time?