case_images: PMC10722160_01
case_images: Arrhythmia in case 1. (A) Atrial flutter with 2:1 conduction; (B) Junctional escape rhythm with atrial standstill; (C) Holter indicated maximum R-R interval of 7.96 s; (D) Gene testing revealed SGN5A gene mutation (C.664C > G).
case_images: fcvm-10-1294197-g001.jpg
case_images: PMC10722160_01_fcvm-10-1294197-g001.jpg
case_images: F1
case_images: At admission, ECG was obtained and it showed atrial flutter with 2:1 conduction (Figure 1A). One day later, the atrial flutter terminated spontaneously and it showed no obvious P wave and significant bradycardia with junctional rhythm (Figure 1B). A subsequent Holter examination indicated paroxysmal atrial fibrillation accompanied by a severe sinus arrest with a minimum ventricular rate of 21 beats per minute and the maximum R-R interval of 7.96 s (Figure 1C). SSS; her stroke was thought to be related to the atrial standstill and thrombosis. Subsequently, genetic testing (whole exome sequencing, Illumina NovaSeq 6,000, Illumina, US) indicated a heterozygous mutation from cytosine C to guanine G (C.664C > G) at nucleotide 664 of SCN5A, causing amino acid no. 222 to change from arginine to glycine (p.R222G) (Figure 1D).
case_images: Arrhythmia in case 2. (A) Atrial flutter with 2:1 conduction; (B) Holter indicated maximum R-R interval of 6.73 s; (C) Gene testing revealed SGN5A gene mutation (c.3823G > A).
case_images: fcvm-10-1294197-g002.jpg
case_images: PMC10722160_01_fcvm-10-1294197-g002.jpg
case_images: F2
case_images: ECG upon admission showed atrial flutter (Figure 2A). However, after the procedure, Holter examination revealed that the minimum ventricular rate was 15 beats per minute and the maximum R-R interval was 6.73 s (Figure 2B). Genetic testing (whole exome sequencing, Illumina NovaSeq 6,000, Illumina, US) revealed a heterozygous mutation in SCN5A located at nucleotide 3,823 from guanine G to adenine A (c.3823G > A), resulting in amino acid no. 1,275 changing from aspartic acid to asparagine (D1275N) (Figure 2C), consistent with her mother's genetic test results.
case_images: Arrhythmia in case 3. (A) Atrial flutter with 2-4:1 conduction; (B) Holter indicated maximum R-R interval of 4.11 s; (C) Gene testing revealed SGN5A gene mutation (c.4895G > A).
case_images: fcvm-10-1294197-g003.jpg
case_images: PMC10722160_01_fcvm-10-1294197-g003.jpg
case_images: F3
case_images: She reported that she had experienced atrial flutter (Figure 3A) for 5 years without symptoms. However, severe bradycardia occurred after the procedure with a minimum ventricular rate of 32 beats per minute and a maximum R-R interval of 4.11 s by Holter monitoring (Figure 3B). Genetic testing (whole exome sequencing, Illumina NovaSeq 6,000, Illumina, US) also demonstrated that she and her mother had the same heterozygous mutation in SCN5A located at position 4,895 from guanine G to adenine A (c.4895G > A), causing amino acid no.1,632 to be altered from arginine to histidine (p.R1632H) (Figure 3C).
case_images: The timelines of the diagnosis and treatment in the three patients. (A) Timeline of case 1; (B) Timeline of case 2; (C) Timeline of case 3. AF, atrial flutter; PM, pacemaker; RA, radiofrequency ablation; SSS, sick sinus syndrome.
case_images: fcvm-10-1294197-g004.jpg
case_images: PMC10722160_01_fcvm-10-1294197-g004.jpg
case_images: F4
case_images: The timelines of the diagnosis and treatment in the three patients are shown in Figure 4.