A 77-year-old woman was admitted to our center in order to implant a pacemaker (PM) because of symptomatic bradycardia. She previously underwent surgical replacement of the mitral and tricuspid valves due to rheumatic stenosis. The patient had history of liver cirrhosis due to Hepatitis C Virus infection, hypertension, dyslipidemia, permanent atrial fibrillation (AF), cerebrovascular disease, renal failure and leuko-thrombocytopenia caused by splenic inhibition. A 12-lead ECG evidenced slow AF, left anterior hemiblock and right bundle brunch block. A previous 24 hours Holter monitoring showed pauses of 3 seconds. At two-dimensional transthoracic echocardiography, the prostheses had normal function, the atria were markedly dilated, the ejection fraction was slightly depressed and the pulmonary artery systolic pressure was 55 mmHg.

A standard transvenous implantation of PM was contraindicated due to the presence of mechanical tricuspid prosthesis. This patient was referred to the cardiac surgery team for epicardial lead implantation, but because of high hemorrhagic and infective risk, the patient was shifted to a percutaneous approach.

After accessing the left subclavian vein, a coronary sinus (CS) guiding catheter was introduced and used to engage the CS ostium. Cannulation of the CS was done in left anterior oblique, right anterior oblique and antero- posterior projection to avoid crossing of the tricuspid valve. The ventricular lead was advanced via the CS and positioned on the epicardial side of the left ventricle (Figure 1). Diaphragmatic stimulation was not observed in this site. The stimulation threshold was 1.4 V at 0.5 ms, R-wave sensing was 7 mV and lead impedance was 980 Ω. A single-chamber rate responsive PM was implanted in the left subcutaneous subclavian region. There were no complications during the procedure. After 1 month, the stimulation threshold was stable, 1.2 V at 0.5 ms, the R-wave sensing was 8 mV and lead impedance was 852 Ω.

We reported a successful case of left ventricular (LV) pacing lead implant in a patient with a mechanical tricuspid prosthesis. Bai et al. were the first to describe two cases of LV pacing through CS in patients with a mechanical tricuspid prosthesis, but they reported elevated stimulation threshold [1] . Recently, other groups described good results of LV pacing in patients with a mechanical tricuspid prosthesis [2] [3] .

In conclusion, the use of LV pacing leads implanted through the CS provides a minimal invasive, safe and effect-

tive strategy of pacing in patients with a mechanical tricuspid prosthesis and high surgical risk.