case_images: PMC11750814_01
case_images: Exercise treadmill test. (A) Baseline ECG. (B) New-onset LBBB at an HR of 109 bpm in stage 4, correlating with the patient's typical symptoms of chest pain. (C) LBBB disappeared as HR decreased to 71 bpm. (D) Syncope after terminating the exercise test at 8 min with a junctional escape rhythm at an HR of 40 bpm and BP 80/50 mmHg after administration of 0.5 mg of sublingual NTG. ECG, electrocardiography; LBBB, left bundle branch block; HR, heart rate; BPM, beats per minute; BP, blood pressure; NTG, nitroglycerin.
case_images: fcvm-11-1438320-g001.jpg
case_images: PMC11750814_01_fcvm-11-1438320-g001.jpg
case_images: F1
case_images: Exercise treadmill testing (modified Bruce protocol) was performed, and the patient presented with chest pain in stage 4 with ECG monitoring, indicating a new onset of LBBB at a heart rate (HR) of 109 bpm (Figure 1B). LBBB disappeared when her HR decreased to 71 bpm (Figure 1C). The patient's symptoms deteriorated rapidly to dizziness and loss of consciousness, with a junctional escape rhythm at an HR of 40 bpm and blood pressure (BP) declining from 142/80 mmHg to 80/50 mmHg (Figure 1D).
case_images: ISO stress UCG test. (A) Baseline ECG before ISO. (B) New-onset LBBB after ISO when HR increased to 120 bpm and chest pain recurred. (C) LBBB and chest pain disappeared when HR decreased to 80 bpm after stopping ISO. (D) Color tissue Doppler M-mode UCG showed baseline SPWMD was 76 ms. (G) Post-ISO SPWMD increased to 156 ms. (F) Baseline TSI. (G) Post-ISO TSI. ISO, isoproterenol; UCG, echocardiography; ECG, electrocardiography; LBBB, left bundle branch block syndrome; BPM, beats per minute; HR, heart rate; SPWMD, septal-to-posterior wall motion delay; TSI, tissue synchronization imaging.
case_images: fcvm-11-1438320-g002.jpg
case_images: PMC11750814_01_fcvm-11-1438320-g002.jpg
case_images: F2
case_images: The continuous ECG monitoring showed the new-onset LBBB when her HR increased from 60 to 120 bpm, and chest pain recurred simultaneously (Figures 2A,B). Table 1). The patient's chest pain and LBBB disappeared when her HR decreased to 80 bpm after terminating ISO (Figure 2C).
case_images: HUTT. The passive phase was negative. Eight min after sublingual NTG in the provocative phase, the patient complained of palpitation and blurred vision, BP decreased from 119/83 to 73/44 mmHg, and HR dropped from 77 to 43 bpm with a sinus rhythm. The patient showed mixed VVS. HUTT, head-up tilt test; NTG, nitroglycerin; BP, blood pressure; HR, heart rate; BPM, beats per minute; VVS, vasovagal syncope.
case_images: fcvm-11-1438320-g003.jpg
case_images: PMC11750814_01_fcvm-11-1438320-g003.jpg
case_images: F3
case_images: HR (from 71 to 85 bpm) after sublingual NTG and thereafter a quick decline in HR and BP, which corresponded to hemodynamic changes in reflex syncope (Supplementary Material). HUTT was performed and verified mixed VVS in the provocative phase (Figure 3).